Robinson R22 Helicopter. MAINTENANCE MANUAL (2018)

23-70 Approved Materials

The following items are available from the noted manufacturer(s) or their distributor(s).

Check with appropriate regulatory authority(s) for allowable usage of materials.

WARNING

Refer to Safety Data Sheet (SDS) and observe precautions

when working in proximity to hazardous materials.

CAUTION

Follow product manufacturer’s instructions for handling and

storage.

23-71 Paint Strippers

PRODUCT

MANUFACTURER/SUPPLIER

APPLICATION

Cee-Bee Stripper

McGean-Rohco: Cee-Bee Division

Metal parts, except blades and flex plates.

A-292

Downey, CA

Plastic Media

Pauli & Griffin Co.

Metal parts except blades and unsupported

Blasting System

Vacaville, CA

sheet metal less than 0.040 inch thick.

23-72 Solvents and Cleaners

PRODUCT

MANUFACTURER/SUPPLIER

APPLICATION

QSOL 220

Safety-Kleen Systems, Inc.

General use and for cleaning prior to applying

Plano, TX

primer, topcoat, adhesive, or sealant.

Benzene, 1-Chloro-4

Any

“ “

(Trifluoromethyl)

PCBTF***

Final Klean 3909S

Du Pont Chemical

Remove adhesive residue on cabin and

Los Angeles, CA

windshield.

EM-Citro*

LPS Laboratories, Inc.

“ “

Tucker, GA

Acetone***

Any

“ “

Lacolene

Any

Windshield and plastic cleaning.

(Aliphatic

Hydrocarbon)

Plexus®

B.T.I. Chemical Co.

“ “

Oak Park, CA

Presolve

LPS Laboratories, Inc.

Hydraulic components only.

Tucker, GA

Tetrachloroethylene

Any

Vapor degreaser.

(Perchloroethylene)

OCT 2018

Chapter 23 Standard Practices

Page 23.19

23-72 Solvents and Cleaners (continued)

PRODUCT

MANUFACTURER/SUPPLIER

APPLICATION

815 GD

Brulin Corporation

Ultrasonic cleaning, general

Indianapolis, IN

use.**

SF50

L&R Mfg. Co.

“ “

Kearny, NJ

#112 Ammoniated or

L&R Mfg. Co.

Ultrasonic cleaning, avionics

#222 Nonammoniated cleaning

Kearny, NJ

components only.

& rinse solution

Cleanup Wipe E-4365

Sontara

Cleaning and drying.

Candler, NC

* May be used on acrylic plastic.

** Mix 5%-20% by volume; titration not required.

*** Acetone and PCBTF may be mixed together at 1:1 ratio.

23-73 Fillers and Putty

PRODUCT

MANUFACTURER/SUPPLIER

APPLICATION

05096 Glazing Putty

Minor surface imperfections.

05861 Dry Guide Coat

St. Paul, MN

31180 Finishing Glaze

SBF1191 Filler

Gearhead Products

“ “

Indianapolis, IN

FE-351 Cream Hardener

Catalyst Systems

“ “

Gnadenhutten, OH

23-74 Torque Seal

PRODUCT

MANUFACTURER/SUPPLIER

APPLICATION

83314 thru 83321

Dykem Cross-Check

Torque seal.

Except 83316 (red)

ITW Pro Brands

Page 23.20

Chapter 23 Standard Practices

OCT 2018

23-75 Primers

PRODUCT

MANUFACTURER/SUPPLIER

APPLICATION

Desoprime CF

PPG Industries

Unlimited.

CA 7422 or CA 7502

Irvine, CA

Water Reducible Epoxy

PPG Industries

Use only where specified.

Primer 44GN072

Irvine, CA

Gray Urethane Primer Filler

Axalta Coating Systems

Scrolls.

LE 3404S

Philadelphia, PA

High Solids Epoxy Primer

Transchem Coatings

Unlimited.

53022 Type III

Los Angeles, CA

High Solids Epoxy Primer

AkzoNobel

Use only where specified.

10P20-44

Waukegan, IL

Spray2Fix HS Epoxy Primer

AkzoNobel

Limited or touch-up use only.

10P20-44SC (Aerosol)

Waukegan, IL

23-76 Powder Coat

PRODUCT

MANUFACTURER

Interpon 100-AL101QF Gray

AkzoNobel

Zinc Rich Epoxy Powder*

Santa Fe Springs, CA

81-2158 Vitralon Gray

Pratt & Lambert Chemical Coatings

Zinc Rich Epoxy Powder*

Buffalo, NY

39/80020 Smooth Matte

Tiger Drylac USA

Black

Cucamonga, CA

Polyester Topcoat Powder*

49/72460 Smooth Glossy

“ “

Gray RAL 7043

Polyester Topcoat Powder*

49/22460 Smooth Glossy

“ “

Yellow RAL 1028

Polyester Topcoat Powder*

PFWF104S9 White

Dupont Co.

Polyester Topcoat Powder*

Wilmington, DE

* Shelf life is 12 months from date of manufacture at ambient temperature.

OCT 2018

Chapter 23 Standard Practices

Page 23.21

23-77 Paints (continued)

CODE

MATERIAL

MANUFACTURER

Flat Black 18BK06 with 18BK006CAT Catalyst

PPG Aerospace; Irvine, CA

A1^{PC-216 Curing Selection}

Abrasion Resistant CTG 23T3-90 Black with

AkzoNobel; Waukegan, IL

PC-216 Curing Selection

Cardinal Industries Finishes;

Semi-gloss Black 3900-05 with 39-SG Catalyst

El Monte, CA

Axalta; Wilmington, DE

B Dark gray Imron AF400/AF700

Alumigrip 4200G15290

AkzoNobel; Waukegan, IL

Randolph Products Co.;

Engine gray IE-8948

Chicopee, MA

Randolph Aircraft Products Co.;

Lycoming Gray G-5436 fast dry engine enamel

Riverside, CA

Lycoming A219 gray engine enamel

Tempo Products; Cleveland, OH

(aerosol can-touch up; shelf life 2 years)

Axalta; Wilmington, DE

D White Imron AF400/AF700

Alumigrip 4200G10208

AkzoNobel; Waukegan, IL

Axalta; Wilmington, DE

E Yellow Imron AF400/AF700

Alumigrip 4200G40227

AkzoNobel; Waukegan, IL

Imron AF400/AF700 Colors

Axalta; Wilmington, DE

Clear Imron AF740

“ “

Flat Clear 666-58-9000 with X-503 activator

AkzoNobel; Waukegan, IL

Axalta; Wilmington, DE

-121 & D-101 tints, 2100-P 2.1 binder, & 9T20 flattener

Deco Technology Group Inc;

Printcolor White Ink MS Series 750-9005

Orance, CA

Printcolor Black Ink MS Series 750-8005

“ “

K Printcolor Maize Yellow Ink MS Series 750-1205

Printcolor Carnation Red Ink MS Series 750-3005

“ “

Printcolor Glass Hardener Series 700

“ “

Gensolve normal speed thinner GS-017L

“ “

Axalta; Wilmington, DE

L Red Imron AF400/AF700

Alumigrip 4200G4

AkzoNobel; Waukegan, IL

Orange Imron AF400/AF700

Axalta; Wilmington, DE

Krylon Div. of Borden

N Krylon 1311 (shelf life 2 years)

Matte Clear (aerosol can)

Columbus, OH

Light gray Imron AF400/AF700

Axalta; Wilmington, DE

Burke Industrial Coatings

P 20-452AMF1 with 16-Black

CURE-F4 activator

Ridgefield, WA

OCT 2018

Chapter 23 Standard Practices

Page 23.23

23-77 Paints (continued)

For limited touch-up of interior and landing gear only:

CODE

MATERIAL

MANUFACTURER

Cardinal Industries Finishes;

Cardinal A-2000-05 Flat black (aerosol can)

Cleveland, OH

Krylon Div. of Borden

Krylon 1613 Semi-Flat Black (aerosol can)

Columbus, OH

23-78 Lubricants

RHC

MANUFACTURER’S

LUBRICANT TYPE

MANUFACTURER

PART NO.

A257-1

Grease

101

Southwestern Petroleum Corp.

(general purpose)

Fort Worth, TX

A257-2

Gear oil

201

Southwestern Petroleum Corp.

SAE 90

Fort Worth, TX

A257-3

Grease

Aero Shell 14

Shell Oil Co.

MIL-G-25537

A257-4

Oil

Dexron II or

Any

(automatic

Dexron II/Mercon or

transmission fluid)

Dexron III/Mercon

A257-6

Grease

Fuelube

Fleet Supplies Inc.

(fuel resistant)

Cleveland, OH

EZ Turn

United-Erie Div. of Interstate Chemical Co.

Erie, PA

A257-7

Dry film lubricant

Lubri-Kote

Mealey Ind. Lubricants

Type A 1040 CR

Cleveland, OH

A257-8

Rubber lubricant

P-80

International Products Corp.

Trenton, NJ

A257-9

Anti-seize

Silver Grade

Loctite Corp.

Newington, CT

A257-10

Substitute A257-16

A257-12

Grease

MobilGrease 28

Exxon Mobil Corp.,

MIL-PRF-81322

Fairfax, VA

A257-16

Engine Oil

Type M 20W-50,

Any

Approved for 0-90° F

SAE J1966

ambient). Substitute

A257-24 as required.

A257-17

Substitute A257-19

A257-19

Valve lubricant and

111

Dow Corning Corp.

sealant compound

Midland, MI

A257-24

Engine oil

SAE 50,

Any

(Approved for >60°F

SAE J1966

ambient)

OCT 2018

Chapter 23 Standard Practices

Page 23.25

23-79 Adhesives and Sealants

RHC

DESCRIPTION

COLOR

MFR. PART NO.

MANUFACTURER

PART NO.

B270-1

Sealant - manganese-cured, fuel

Gray

AC-730 B-*

3M Co.

resistant (2-part)

St. Paul, MN

B270-2

Substitute B270-1

B270-4

Substitute B270-13

B270-5

Sealant - synthetic rubber putty

White

Q4-2805

Dow Corning Corp.

(1-part)

Light Gray

94-031

Midland, MI

B270-6

Sealant & lubricant - thread

Gray

Titeseal 55

Radiator Spec. Co.

(1-part)

Charlotte, NC

B270-7

Substitute B270-14

B270-8

Adhesive - rubber, nitrile/acetone

Tan

C 160

Stabond Corp.

(1-part)

Gardena, CA

Adhesive - rubber, nitrile/acetone

Tan

843

3M Co.

(1-part)

St. Paul, MN

B270-9

Adhesive - epoxy, structural,

Gray

2216 B/A

3M Co.

flexible (2-part)

St. Paul, MN

B270-10

Adhesive/sealant - threadlocker,

Red

271

Henkel Loctite Corp.

anaerobic, tight-fits (1-part)

Rocky Hill, CT

B270-11

Adhesive/sealant - threadlocker,

Red

277

Henkel Loctite Corp.

anaerobic, loose-fits (1-part)

Rocky Hill, CT

B270-12

Sealant - electrical potting (2-part)

Any color

MIL-PRF-8516

Any

except red

Type II, Class 2,

Category A or B

B270-13

Sealant - silicone rubber,

Translucent

3145

Dow Corning Corp.

noncorrosive (1-part)

Midland, MI

B270-14

Substitute B270-8

B270-15

Adhesive - plastic, for vinyl

Clear

2262

3M Co.

(1-part)

St. Paul, MN

B270-16

Substitute B270-14

B270-17

Adhesive - cyanoacrylate, instant

Clear

Super Bonder

Henkel Loctite Corp.

(1-part)

495

Rocky Hill, CT

B270-18

Adhesive - weatherstrip (1-part)

Black

051135-08008

3M Co.

St. Paul, MN

B270-19

Adhesive - epoxy structural, rigid

Green

1838 B/A

3M Co.

(2-part)

St. Paul, MN

B270-20

Adhesive/sealant - threadlocker,

Purple

222 or 222MS

Henkel Loctite Corp.

anaerobic, non-permanent (1-part)

Rocky Hill, CT

B270-21

Protectant - corrosion, non-drying

Lt. Amber

LPS 3

LPS Laboratories, Inc.

(1-part)

Tucker, GA

Page 23.26

Chapter 23 Standard Practices

OCT 2018

23-79 Adhesives and Sealants (continued)

RHC PART

DESCRIPTION

COLOR

MFR. PART NO.

MANUFACTURER

NO.

B270-22

Protectant - corrosion, drying

Amber

LPS Hardcoat

LPS Laboratories, Inc.

(1-part)

Tucker, GA

B270-23

Sealant - gasket (1-part)

Brown

GM3H (Gasket

Perfect Seal, Inc.

Maker #4)

Cincinnati, OH

Sealant - gasket (1-part)

Brown

JV66B

Dana Corp.;

Churubusco, IN

(Victor Reinz Brand)

B270-24

Activator/primer - anaerobic

Translucent

7649

Henkel Loctite Corp.

adhesive (1-part)

Green

Rocky Hill, CT

B270-25

Clear coat - automotive touch

Clear

Clear Coat

Automotive Touchup

up, brush in bottle (1-part)

Touch up Bottle

Harahan, LA

B270-26

Sealant - polysulfide, window

Black

AC-251 B-1

3M Co.

glazing (2-part)

St. Paul, MN

B270-27

Adhesive - epoxy, high strength

Translucent

EA 9309NA

Henkel Loctite Corp.

structural, flexible (2-part)

Red Blue

EA 9309.2NA

Rocky Hill, CT

B270-28

Substitute B270-27

* Dash number for minimum hours application life may be -½, -2, -6, or -12.

OCT 2018

Chapter 23 Standard Practices

Page 23.27

23-80 Miscellaneous Practices

23-81 Part Interchangeability

Refer to R22 Illustrated Parts Catalog for part interchangeability information.

23-82 Thermal Fitting Parts

General Procedures for using heat to fit parts during assembly or evaluating parts that

may have been overheated in service:

Aluminum parts must not be heated above 200º F for more than 5 minutes. Higher

temperatures or longer times adversely affect strength and corrosion properties. Scrap

any aluminum parts suspected of going above 325º F regardless of time at temperature.

Steel parts (bare) - Maximum temperature 300º F. Higher temperature can reduce the

strength or cause temper brittleness in some alloys.

Steel parts (cadmium plated) - Maximum temperature 300º F. Higher temperatures

will melt the plating and adversely affect steel strength by a process called liquid metal

embrittlement.

Bearings and carburized parts such as gears, clutch shafts, and clutch housings should

not be heated above 300º F. Higher temperatures will reduce the surface hardness and

increase wear rates.

Always heat parts in an oven with temperature control set no greater than the maximum

temperature allowed for the part.

Always attach a pyrometer and thermocouple to the smallest aluminum part in the oven.

Never depend on the oven control to determine part temperature.

Cooling a part for thermal fitting at assembly is not recommended. Water vapor from the

air will condense on the part and frequently introduce water into the assembly causing

severe internal corrosion over time.

23-83 Replacement Component Identification (Data) Plates

In order to issue a replacement component identification plate for field installation, RHC

must first receive the old identification plate in legible condition. If old identification

plate is lost or destroyed, then RHC must have an original letter (photocopies or faxes

are NOT acceptable) from customer’s Civil Aviation Authority authorizing identification

plate replacement AND stating component name, part number, and serial number for each

requested identification plate. There is a charge for each plate issued.

Identification plates may be carefully removed using a sharp plastic scraper. If necessary,

use a heat gun to soften plate adhesive. Retain in a dry, contaminate-free area until ready

for reinstallation.

Damp wipe local area with acetone or equivalent solvent prior to reinstallation. Residual

adhesive on identification plate is usually sufficient for good adhesion. If necessary, use

B270-9 adhesive or equivalent to secure.

Page 23.28

Chapter 23 Standard Practices

OCT 2018

23-85 Storage Limits

1. B283 hoses have a shelf storage life of 5 years. Hose service life is “on condition”,

with a maximum of 12 years.

2. Elastic cords have a shelf storage life of 5 years. Elastic cord service life is “on condition”,

with a maximum of 12 years. Use invoice or FAA Form 8130 date as start date.

3. Store V-belts at less than 85º F (30º C), with relative humidity below 70%. Avoid

solvent and oil vapors, atmospheric contaminants, sunlight, and ozone sources (electric

motors, arc welding, ionizing air purifiers, etc.). Belt shelf life is 4 years if preceding

recommendations are followed. Use invoice date or FAA Form 8130 date as start date.

4. Oils and greases have a 5 year shelf life when stored and kept sealed in their original

container. Use invoice date or FAA Form 8130 date as start date unless the manufacturer

has marked container with manufacture date (in which case use manufacture date as

start date).

5. Rubber o-rings, seals, and gaskets have a twenty (20) quarter, five (5) year shelf life

from the indicated cure date. Fluorocarbon (Viton) and silicon rubber products shall

adhere to manufacturer’s expiration date(s). Service life is “on condition” with a

maximum of 12 years.

6. Store uninstalled fuel bladder in original container (if available) at 70°F to 80°F and

below 70% humidity. Coat bladder with clean, non-detergent engine mineral oil to

prevent rubber from drying out and cracking. Store bladder in relaxed condition free

from tension, compression, or other deformation such as creases or folds.

23-86 B526 Screws and B527-08 Washers

B526 (TORX Plus®) truss head screws may be used to secure cowlings and access panels.

A B527-08 nylon washer may be used under a B526 screw head to further protect thin

or painted surfaces.

B526 screws are interchangeable with MS27039C080_ screws used to secure cowlings

and access panels as follows:

PART:

INTERCHANGEABLE WITH:

MS27039C0806 screw

B526-6 screw

MS27039C0807 screw

B526-8 screw

MS27039C0808 screw

B526-8 screw

B526 screws are interchangeable with AN525-832R_ & AN526C832R_ screws as follows:

PART:

INTERCHANGEABLE WITH:

AN525-832R6 or AN526C832R6 screw

B526-6 screw

AN525-832R7 or AN526C832R7 screw

B526-8 screw

AN525-832R8 or AN526C832R8 screw

B526-8 screw

NOTE

B526 screws are compatible with T20 or 20IP drivers.

Page 23.30

Chapter 23 Standard Practices

OCT 2018

CHAPTER 24

LIGHTS

24-00 Description

A red anti-collision light is installed on the tailcone and is controlled by the strobe switch.

Position lights are installed on each side of the cabin and in the tail and are controlled by

the nav lights switch. Post and internal lights (earlier aircraft) or a light at the top of the

windshield (later aircraft) illuminate the instruments. Instrument lighting is active when the

nav lights switch is on and lighting is dimmed via the knob above the nav lights switch.

An overhead map light mounted on a swivel is controlled by an adjacent switch. The map

light may be used for emergency lighting of the instrument panel.

Two landing lights are installed in the nose at different vertical angles to increase lighted

area. One landing light switch controls both lights and is located on the cyclic center post

or near OAT gage.

NOTE

Landing lights operate only when clutch actuator switch is in

the engage position.

24-10 Exterior Lights

24-11 Strobe Light

A. Removal

1. Turn battery switch off. Pull out STROBE circuit breaker (5 amp) at panel.

2. Remove hardware securing A708 strobe light assembly's retainer (or clamp),

lens, and gasket to strobe (or flash tube assembly).

3. Remove screws securing A708-14 strobe to tailcone mount.

4. Disconnect strobe (or flash tube assembly) wire harness from airframe harness at

connectors and remove strobe (or flash tube assembly).

OCT 2018

Chapter 24 Lights

Page 24.1

24-11 Strobe Light (continued)

B. Installation

1. Turn battery switch off. Pull out STROBE circuit breaker (5 amp) at panel.

2. Connect A708 strobe light assembly’s wire harness to airframe harness at

connectors. Verify security.

3. Loop wires and connectors inside mount and install screws securing A708-14

strobe to tailcone mount.

4. Assemble gasket, lens (red forward if red/white), and retainer (or clamp) on

tailcone mount and install hardware. Verify security.

5. Push in STROBE circuit breaker (5 amp) at panel. Turn battery switch and strobe

switch(es) on and verify function. Turn battery switch off.

24-12 Navigation Lights

A. Removal

1. Turn battery switch off. Pull out LTS circuit breaker (5 amp) at panel.

2. a. Position Lights: Remove screw, retainer, lens, (lamp), and gasket to light

assembly. Remove hardware securing light assembly, gasket, and ground

wire to chin. Cut and discard ty-rap securing excess wire to light assembly,

pull out light assembly, and disconnect light assembly harness from airframe

harness at connectors.

b. Tail Light: Remove screws securing retainer, lens, gasket, (lamp), and light

assembly to stabilizer mount. Pull out light assembly and disconnect light

assembly harness from airframe harness at connectors.

B. Installation

1. Turn battery switch off. Pull out LTS circuit breaker (5 amp) at panel.

2. a. Position Lights: Connect light assembly harness to airframe harness at

connectors. Install hardware securing light assembly, gasket, and ground wire

to chin. Verify security. Install ty-rap securing excess wire to light assembly.

Cinch ty-rap until snug without over-tightening, and trim tip flush with head.

Install lamp (earlier R22s). Install screw securing retainer, lens, and gasket to

light assembly. Verify security.

b. Tail Light: Connect light assembly harness to airframe harness at connectors.

Position light assembly in stabilizer mount and install screws securing retainer,

lens, gasket, and light to mount. Verify security.

3. Push in LTS circuit breaker (5 amp) at panel. Turn battery switch and NAV LTS

switch on and verify function. Turn battery switch and NAV LTS switch off.

Page 24.2

Chapter 24 Lights

OCT 2018

24-13 Landing Lights

NOTE

Landing lights operate only when clutch actuator switch is in

the engage position.

A. Removal

1. Turn battery switch off. Pull out LAND LT circuit breaker (15 amp for HIDs, 20

amp for B196-26 lamps) at panel.

2. Remove screws securing A526-1 retainer to chin and remove retainer.

3. Unplug landing light cable from (or remove hardware securing landing light wires

to) lamp and remove lamp.

B. Installation

1. Turn battery switch off. Pull out LAND LT circuit breaker (15 amp for HIDs, 20

amp for B196-26 lamps) at panel.

2. a. HIDs: Connect landing light cable to B557-1 (spot; LH) landing light or B557-2

(flood) taxi light, as required. Verify security.

b. B196 lamps: Install hardware securing landing light wires to lamp. Verify

security.

3. Install screws securing A526-1 retainer to chin.

4. Push in LAND LT circuit breaker (15 amp for HIDs, 20 amp for B196-26 lamps)

at panel. Turn battery switch and landing light switch on (cyclic center post) and

verify function. Turn battery switch and landing light switch off.

OCT 2018

Chapter 24 Lights

Page 24.3

24-20 Interior Lights

24-21 Instrument Lighting

A. LED Assembly Replacement

1. Turn battery switch off. Pull out LTS circuit breaker (5 amp) at panel.

2. Remove hardware securing G196-6 light assembly to windshield stiffener.

Remove two cap screws securing cover and LED-lamp assembly to housing.

Disconnect lamp wires from airframe harness and remove lamp.

3. Connect A238-2289 (white) airframe harness wire to LED-lamp assembly red

wire, and A238-2290 airframe harness wire to lamp black wire. Install cover

(chamfer facing away from housing) and install two cap screws. Install hardware

securing G196-6 light assembly to windshield stiffener. Verify security.

4. Push in LTS circuit breaker (5 amp) at panel. Turn battery switch and NAV LTS

switch on and verify function. Verify dimming knob adjusts brightness. Turn

battery switch and NAV LTS switch off.

Page 24.4

Chapter 24 Lights

OCT 2018

CHAPTER 25

DOORS AND WINDOWS

25-00 Description

Both cabin doors may be removed and installed by maintenance personnel or pilots.

25-10 Door Assembly

A. Removal

Remove cotter pins from door hinge pins. Open door and lift door pins from door

frame hinge assemblies and remove door. Adjust weight and balance as required.

B. Installation

WARNING

Failure to install a cotter pin in each door's two hinge pins may

allow door to depart aircraft in flight.

1. Align and insert door hinge pins in door frame hinge assemblies; latch door.

2. Install a cotter pin in both upper and lower door hinge pins.

3. Adjust weight and balance as required.

OCT 2018

Chapter 25 Doors and Windows

Page 25.1

25-20 Windshield Assembly

A. Removal

1. Remove forward door and hinges.

NOTE

To prevent scratching windshield, a protective cover should

be taped to the inside and outside of the windshield prior to

removal.

2. Remove screws and side retainer holding windshield.

3. Reinstall hinges and doors for cabin structure support with windshield removed.

4. Remove screws and retainers (upper, lower, and middle) holding windshield.

5. Clean silicone from retainers.

6. Clean silicone from windshield for reinstallation.

Installation

1. Remove all old silicone from cabin, retainers and windshield.

2. Install windshield and cleco retainer strips.

3. Mask windshield along edge of retainer strips with 1/2” masking tape. This will

catch silicone rubber squeeze-out on installation of retainer strips.

4. Remove retainer strips.

5. To ensure a proper seal, run a bead of B270-13 silicone rubber along entire edge

of tape line.

6. While holding windshield in place, cleco retainer strips (center, upper and lower)

into place.

7. With doors installed and closed, tighten center retainer strip first. Then tighten

upper and lower retaining strips. A second person will be required to tighten nuts

inside ship.

8. When center, upper and lower retaining strips are secure, remove door and hinges

for side strip installation.

9. Install side retainer strip.

10. Reinstall hinges and door. Ensure all fasteners are tight.

11. Fill any gap between retainer and window with B270-13 silicone rubber.

12. Remove masking tape next to retainers. Be careful not to smear wet silicone.

13. Clean any silicone off windshield after it has been allowed to dry.

OCT 2018

Chapter 25 Doors and Windows

Page 25.3

25-20 Windshield Assembly (continued)

C. Inspection

1. Inspect windshield for cracks and crazing adjacent to retainer strips per Figure

25-1. If cracks exceed these limits, replace windshields per § 25-20 Part D.

D. Replacement

1. Remove all old silicone on cabin and retainers if they are to be reused.

2. Cleco all window retaining strips in place, checking for proper alignment.

3. Install hinges and doors in door frames and secure. Remove bottom and center

retaining strips, leaving side retaining strip to hold door and door frame in position.

4. Hold windshield in place by hand, and align it with frame according to contour of

frame and windshield.

5. Mark windshield for trim using non-permanent marker, such as grease pencil or

masking tape.

6. Trim to mark. A band saw is recommended. Band saw blade should contain at

least 24 teeth per inch.

NOTE

Tape cardboard to band saw table to prevent scratching of

windshield. Saw carefully to prevent binding of saw blade and

cracking windshield.

7. Hold windshield in place and check for fit. Re-trim as necessary.

8. After windshield is fitted, carefully sand or scrape edges smooth.

9. Install windshield per § 25-20 Part B.

Page 25.4

Chapter 25 Doors and Windows

OCT 2018

CHAPTER 26

MAIN ROTOR

Section Title

Page

26-00

Description

26.1

26-10

Main Rotor Blades

26.1

26-11

Blade Boots

26.6

26-12

Filling Pitch Bearing Housing

26.9

26-20

Main Rotor Hub

26.10

26-21

Bearing Replacement

26.12

26-30

Main Rotor Assembly

26.15

26-31

Journal and Shim Calculations

26.15

26-32

Adjusting Hinge Friction

26.20

26-33

Shifting the Main Rotor Hub

26.21

26-34

Drilling Installed Main Rotor Hub Bolts

26.21

26-40

Inspection of Main Rotor Blades

26.23

26-41

Scratches and Corrosion on Blade Skins and Doublers

26.23

26-42

Dents

26.25

26-43

Root Fitting Damage

26.27

26-44

Voids

26.29

26-50

Repair of Main Rotor Blades

26.31

26-51

Trimming

26.33

26-52

Painting

26.33

OCT 2018

Chapter 26 Main Rotor

Page 26.i

CHAPTER 26

MAIN ROTOR

26-00 Description

The main rotor has two all-metal blades mounted to the hub by coning hinges. The hub is

mounted to the shaft by a teeter hinge. The coning and teeter hinges use self-lubricated

bearings. Droop stops for the main rotor blades provide a teeter hinge friction restraint

which normally prevents the rotor from teetering while starting or stopping. Pitch change

bearings for each blade are enclosed in a housing at the blade root. The housing is filled

with oil and sealed with an elastomeric boot. Each blade has a thick stainless steel spar at

the leading edge which is resistant to corrosion and erosion. The skins are bonded to the

spar approximately one inch aft of the leading edge. Blades must be refinished if the paint

erodes to bare metal at the skin-to-spar bond line. Bond may be damaged if bond line is

exposed.

26-10 Main Rotor Blades

WARNING

Due to potentially destructive results, use of blade tape (anti-

erosion tape) is prohibited.

A. Removal

Refer to Figure 26-1. Four people will be required to remove the blades. One person

must support the blade near the blade tip while another supports the root and removes

or installs the attachment bolt.

FIGURE 26-1 SUPPORTING MAIN ROTOR BLADES DURING BLADE REMOVAL OR INSTALLATION

OCT 2018

Chapter 26 Main Rotor

Page 26.1

26-10 Main Rotor Blades (continued)

A. Removal (continued)

Mark one main rotor blade and its corresponding hub location, pitch link, and

retaining nut & bolt with “X” using a marker or grease pencil. Mark opposite blade

and its hub location, pitch link, and retaining nut & bolt with “O”.

Measure and record coning hinge axial gaps per Figure 26-8.

Remove hardware securing main rotor pitch links to blade pitch horns.

Remove cotter pins and loosen blade coning hinge retaining nuts until finger tight.

CAUTION

After removing one blade, support installed blade in a level

position until it is removed.

Remove nut, thrust washer, and trailing-edge shims (if used) from one blade. Cone

blade as required to position spindle tusk off of droop stop. Supporting blade at

root, rotate pitch horn down, and remove hinge bolt and thrust washer.

CAUTION

Do not drop journals (inside hub bearings) which can slide out

when removing blade bolt.

NOTE

Blade installation hardware is specific to each blade, each

blade’s leading and trailing edge, and each blade’s location in

hub. It is good practice after blade removal to install hardware

in hub finger tight exactly as removed.

Place blade on a cushioned surface to prevent damage to skins.

Remove opposite blade per steps 5 and 6.

OCT 2018

Chapter 26 Main Rotor

Page 26.3

26-10 Main Rotor Blades (continued)

B. Installation

Identify hub and spindle part numbers and ensure correct corresponding installation

hardware.

Check teeter hinge friction and adjust as required per § 26-32.

If coning hinge axial gap recorded during blade removal was beyond tolerance, or if

corresponding hub bearing(s) or spindle was replaced, perform coning hinge journal

and shim calculation per § 26-31.

Level hub and insert journals in hub bearings. Install thrust washer on blade bolt.

Insert main rotor blade spindle in hub and align spindle and journal bores. Cone

blade as required to position tusk off of droop stop. Rotate pitch horn down and

install hinge bolt at leading-edge side.

NOTE

A bolt may be inserted from trailing-edge side to align spindle and

journal bores (it is pushed out as coning hinge bolt is installed).

Install trailing-edge shims (if used) and thrust washer. Apply light coat A257-9

anti-seize to bolt threads and nut face. Install nut finger tight.

NOTE

Do not allow anti-seize to contact journals, shims, or hub bearing

areas. These areas must be clean and dry.

CAUTION

After installing one blade, support blade in a level position until

opposite blade is installed.

Install opposite blade per steps 4 thru 6.

Tighten nut on coning hinge bolt until journals and thrust washer are firmly seated.

Loosen nut until both thrust washers can be freely rotated.

Refer to Figure 26-2. Install MT122 main rotor bolt elongation (stretch) tool on

hinge bolt. Zero dial indicator by rotating dial face and lock dial. Remove tool.

10.

Using wrenches with at least 150 ft-lb torque capacity, tighten nut until drilled

holes in nut and bolt align. Install MT122 tool and measure bolt elongation:

WARNING

Do not under-stretch or over-stretch teeter or coning hinge

bolts to obtain proper clamping force. Under-stretching or over-

stretching can cause failure.

Page 26.4

Chapter 26 Main Rotor

OCT 2018

26-10 Main Rotor Blades (continued)

B. Installation (continued)

10. a. A154-1 hub with NAS630-80 (or MS21250-10080) coning hinge bolts:

i. If bolt elongation is 0.015-0.017 inch, remove tool and install a new

cotter pin wet with epoxy primer.

ii. If bolt elongation is not 0.015-0.017 inch, remove old nut and old bolt

and install a new bolt and a new nut. Stretch new bolt per § 23-33, and

drill new nut and bolt per § 26-34. Install a new cotter pin wet with

epoxy primer.

b. B370-1 hub with NAS632-82 (or MS21250-12082) coning hinge bolts:

i. If bolt elongation is 0.010-0.012 inch, remove tool and install a new

cotter pin wet with epoxy primer.

ii. If bolt elongation is not 0.010-0.012 inch, remove old nut and old bolt

and install a new bolt and a new nut. Stretch new bolt per § 23-33, and

drill new nut and bolt per § 26-34. Install a new cotter pin wet with

epoxy primer.

11. Install hardware securing main rotor pitch link to pitch horn. Standard torque

hardware per § 23-32 and torque stripe per Figure 2-1.

12. Perform steps 8 thru 11 on opposite blade.

13. Track and balance main rotor blades per § 10.230.

OCT 2018

Chapter 26 Main Rotor

Page 26.5

26-11 Blade Boots

A. Removal

1. Remove main rotor blades per § 26-10.

2. Place a suitable drain container below pitch horn. Remove two B289-2 bolts and

drain fluid.

3. Remove outer boot clamp and hold boot back to expose inner boot clamp. Remove

inner clamp and peel boot from spindle.

B. Installation

1. Visually inspect and verify boot is undamaged. Carefully stretch new boot over

spindle.

2. Solvent-clean surfaces clamped by boot inner lip. Properly position boot inner lip;

install A165-1 (inner) clamp assembly and tighten clamp to 2.330 ± 0.005 inch

outside diameter. Rotate spindle and verify adequate clearance between clamp

assembly and pitch horn.

NOTE

When installing inner clamp, ensure that shoulder of boot inner

lip is not wedged beneath clamp or clamp may loosen in service.

Inspect boot interior and verify no cuts or punctures.

3. Stretch boot outer lip over pitch horn flange. Rotate spindle and align pitch horn

bolt hole with spindle bolt hole per Figure 26-3. Install A165-7 (outer) clamp

assembly and tighten clamp. Verify security.

4. Fill pitch bearing housing per § 26-12.

Page 26.6

Chapter 26 Main Rotor

OCT 2018

26-12 Filling Pitch Bearing Housing

NOTE

MT147-1 Main rotor blade spindle air bleed tool includes supply

container, hose assemblies, and bleed fittings.

WARNING

Refer to Safety Data Sheets (SDS) and observe precautions

when working in proximity to hazardous materials.

Remove main rotor blades per § 26-10.

Refer to Figure 26-3. Place a suitable drain container below main rotor pitch horn.

Remove two B289-2 bolts from pitch horn and drain fluid.

Install MT147-2 bleed fittings into pitch horn openings. Attach drain hose assembly

to (top) bleed fitting, secure with two wraps of lockwire. Position drain hose into drain

container.

Place supply container with sufficient A257-4 fluid approximately 3 feet above spindle.

Route fill hose assembly into drain container and open brass valve. Open supply

container plastic valve and purge air from fill hose. Close valves.

Connect brass valve to (bottom) bleed fitting by tightening brass compression sleeve.

Open valves and fill spindle housing until no air bubbles are visible in drain hose

assembly. Massage spindle boot, oscillate spindle, and raise blade tip up & down to

remove trapped air.

Remove drain hose assembly and (top) bleed fitting, and install B289-2 bolt. Roll the

blade over. After five minutes, inspect the boot for leaks. If no leaks are found, close

valves, remove fill hose assembly brass valve and (bottom) bleed fitting, and install

other bolt.

Special torque B289-2 bolts per § 23-33 and torque stripe per Figure 2-1.

Repeat steps for opposite blade.

OCT 2018

Chapter 26 Main Rotor

Page 26.9

26-20 Main Rotor Hub

A. Removal

1. Remove main rotor blades per § 26-10.

2. Refer to Figure 26-5. Mark rotor hub using a grease pencil, tape, or soft marker as

follows:

a. Indicate nut side of teeter bolt.

b. Indicate chord arm side of drive shaft.

3. If same hub will be installed, measure teeter hinge friction per Figure 26-9 and

record value.

4. Remove cotter pin, nut, A152 thrust washers, A117 shims, A106 journals, and

bolt. Rotate hub as required and remove hub. Do not drop thrust washers or

journals.

5. Reinstall bolt, thrust washers, shims, journals, and nut in rotor hub exactly as

removed.

CAUTION

Main rotor chordwise balance is adjusted using A106 journals

and A117 shims. If assembly stack-up is altered, an out-of-

balance condition can occur.

B. Installation

1. Clean and dry teeter hinge hardware using approved solvent per § 23-70. Inspect

journals and thrust washers for chipping of chrome plating, corrosion, and/or wear

grooves extending through chrome plating. Replace journal or thrust washer if any

of these conditions exist.

2. If teeter hinge friction recorded during hub removal was less than 5 ft-lb or more

than 15 ft-lb, if teeter hinge hub bearing(s) was replaced, or if previous installation

information is unavailable, perform teeter hinge journal and shim calculation per

§ 26-31.

3. Refer to Figure 26-5. Line up mark on hub with chord arm on drive shaft. Install

teeter hinge bolt, thrust washers, shims, and journals (if previous installation

information is available, install parts exactly as removed).

Page 26.10

Chapter 26 Main Rotor

OCT 2018

26-20 Main Rotor Hub (continued)

B. Installation (continued)

Coat nut face and bolt threads with A257-9 anti-seize compound, install and

tighten nut, then loosen nut until both thrust washers can be freely rotated. Ensure

journals do not “pinch” droop stops and fully contact drive shaft.

WARNING

Do not allow anti-seize compound to contaminate drive shaft,

journals, shims, or thrust washer inner faces. Contamination

prevents proper joint clamp-up and may cause failure.

Refer to Figure 26-2. Install MT122 main rotor bolt elongation (stretch) tool on

teeter bolt. Zero dial indicator by rotating dial face and lock dial. Remove tool.

Using wrenches with at least 150 ft-lb torque capacity, tighten nut until drilled

holes in nut and bolt align. Install MT122 tool and measure bolt elongation:

a. If bolt elongation is 0.015-0.017 inch, remove tool and verify correct teeter

hinge friction per § 26-32. Adjust teeter hinge friction as required.

b. If bolt elongation is not 0.015-0.017 inch, remove old nut and old bolt and

install a new bolt and a new nut. Stretch new bolt per § 23-33 and verify

correct teeter hinge friction per § 26-32. Adjust teeter hinge friction as

required. Drill new nut and bolt per § 26-34.

WARNING

Do not under-stretch or over-stretch teeter or coning hinge

bolts to obtain proper clamping force. Under-stretching or over-

stretching can cause failure.

Install a new cotter pin wet with epoxy primer.

OCT 2018

Chapter 26 Main Rotor

Page 26.11

FIGURE 26-4 MAIN ROTOR HUB BEARING REPLACEMENT

26-21 Bearing Replacement

Remove main rotor hub per § 26-20.

Refer to Figure 26-4. Verify tooling surfaces are smooth to avoid damaging hub and

bearings. Press A648-1 and/or A648-3 bearing(s) from hub using MT329-1 plug

assembly (Rev H or subsequent) with MT329-10 tube. Press A648-2 bearing(s) from

hub using MT329-11 plug assembly with MT329-10 tube.

Visually inspect hub bearing bore(s) per § 2.610 step 3a.

NOTE

Do not allow epoxy primer to contact bearing’s Teflon liner.

Verify bearing mating surfaces are smooth and clean and apply light coat of epoxy

primer (refer to § 23-70). If visible, orient coning hinge bearing’s Teflon liner seam

toward top of hub. While primer is wet, press in new A648-1 and/or A648-3 bearing(s)

using MT329-1 plug assembly or A648-2 bearing(s) using MT329-11 plug assembly

(always use MT329-13 or MT329-2 [A154-4 Hub] support when replacing coning

hinge bearing) until bearing flange is completely seated against hub.

Using a syringe, seal between bearing’s outboard flange and hub and bearing’s inboard

edge and hub with small fillet of epoxy primer.

Page 26.12

Chapter 26 Main Rotor

OCT 2018

26-30 Main Rotor Assembly

26-31 Journal and Shim Calculations

Refer to Table 26-1 and Figures 26-5, 26-6, and 26-7.

A. Teeter Hinge Calculation

Measure main rotor hub width across the teeter hinge bearing faces:

in.

Subtract measured width of A251 driveshaft at teeter hinge bolt hole: -

in.

Calculated empty space: =

in.

Assemble thrust washer, one A117-7 shim (0.020 inch), and one

A106-4 journal (1.300 inches) under the teeter bolt head and insert

bolt thru hub and drive shaft.

Subtract combined measured thickness of A117-7 shim &

A106-4 journal: -

in.

Difference: =

in.

Subtract measured length of nut-side A106-4 or A106-5 journal:

in.

Difference: =

in.

CAUTION

Initial teeter hinge hardware stack-up must be adjusted to

0.005/0.008 inch greater than calculated empty space. A

smaller initial stack-up could damage thrust washers and hub

bearings during installation.

To accommodate dimensional change due to clamping force, add: + 0.005/

0.008

in.

Initial A117 shim stack between nut-side journal & thrust washer: =

in.

NOTE

Use as many different size A117 shims as possible to facilitate

head shifting during balancing.

Refer to § 26-32. Adjust shim stack as required to meet teeter hinge friction

requirement (less than 15 ft-lb).

OCT 2018

Chapter 26 Main Rotor

Page 26.15

FIGURE 26-7 A154-1 HUB CONING HINGE (BLADE INSTALLATION; VIEW LOOKING DOWN)

A106 Journal Lengths

Part No.

Length

Location

A106-1

1.000 in.

Coning hinge, no shims (A154-1 Hub)

A106-2

0.995 in.

Coning hinge, no shims (A154-1 Hub)

A106-3

0.990 in.

Coning hinge, no shims (A154-1 Hub)

A106-4

1.300 in.

Teeter hinge (two, or one + A106-5 per hinge), shims

A106-5

1.260 in.

Teeter hinge (none, or one + A106-4 per hinge), shims

A106-6

1.005 in.

Coning hinge, no shims (A154-1 Hub)

A106-7

1.005 in.

Coning hinge (B370-1 Hub)

A117 Shim Sizes

Part No.

Thickness

Location (Between thrust washer and journal)

A117-5

0.012 in.

Teeter hinge

A117-6

0.015 in.

Teeter hinge

A117-7

0.020 in.

Teeter hinge

A117-8

0.025 in.

Teeter hinge

A117-48

0.012 in.

Coning hinge (B370-1 Hub)

A117-49

0.015 in.

Coning hinge (B370-1 Hub)

A117-50

0.020 in.

Coning hinge (B370-1 Hub)

A117-51

0.025 in.

Coning hinge (B370-1 Hub)

TABLE 26-1 A106 JOURNAL LENGTHS AND A117 SHIM SIZES

Page 26.16

Chapter 26 Main Rotor

OCT 2018

26-31 Journal and Shim Calculations (continued)

B. Coning Hinge Calculation

B370-1 Hub:

1. Measure main rotor hub width across the coning hinge bearing faces:

in.

2. Subtract measured width of blade spindle at teeter hinge bolt hole:

in.

Calculated empty space: =

in.

3. Subtract combined measured length of two A106-7 journals:

in.

Difference: =

in.

CAUTION

Initial teeter hinge hardware stack-up must be adjusted to

0.003/0.006 inch greater than calculated empty space. A

smaller initial stack-up could damage thrust washers and hub

bearings during installation.

4. To accommodate dimensional change due to clamping force, add: + 0.003/

0.006

in.

Initial A117 shim stack between nut-side journal & thrust washer: =

in.

5. Adjust shim stack combination as required to meet coning hinge axial gap

requirement per Figure 26-8 and to maintain teeter friction requirement as follows:

It must be possible to manually cone each blade without teetering the hub when

blades are held up off the droop stops and lifted at tip.

OCT 2018

Chapter 26 Main Rotor

Page 26.17

26-31 Journal and Shim Calculations (continued)

B. Coning Hinge Calculation (continued)

A154-1 Hub:

1. Measure main rotor hub width across the coning hinge bearing faces:

in.

2. Subtract measured width of blade spindle at coning hinge bolt hole: -

in.

Calculated empty space: =

in.

CAUTION

Initial coning hinge hardware stack-up must be adjusted to

0.003/0.006 inch greater than calculated empty space. A

smaller initial stack-up could damage thrust washers and hub

bearings during installation.

3. To accommodate dimensional change due to clamping force, add:

+ 0.003/

0.006

in.

Sum: =

in.

4. Select a combination of A106-1, -2, -3, or -6 journals whose combined measured

lengths equal Sum. The same journal dash number must be used under the head

of both coning hinge bolts to maintain symmetry.

5. Adjust journal combination as required to meet coning hinge axial gap requirement

per Figure 26-8 and to maintain teeter friction requirement as follows: It must be

possible to manually cone each blade without teetering the hub when blades are

held up off the droop stops and lifted at tip.

OCT 2018

Chapter 26 Main Rotor

Page 26.19

26-32 Adjusting Hinge Friction

A. Teeter Hinge Friction Adjustment

1. Remove main rotor blades per § 26-10.

2. Refer to Figure 26-5 and Table 26-1. Remove cotter pin, nut, thrust washer,

and nut-side A117 shims. Adjust teeter hinge friction by changing nut-side shim

stack thickness in small increments; reducing shim stack thickness increases

friction, increasing shim stack thickness reduces friction. Install shims, thrust

washer, and nut.

3. Refer to Figure 26-9. While torquing teeter hinge bolt per § 23-33, check teeter

hinge friction frequently. To check friction, install MT354 teeter friction tool

into coning hinge bearings on one side of main rotor hub and measure moving

force (not breakaway force) required to teeter main rotor hub with a spring scale.

Teeter friction must be less than 15 ft-lb.

4. Install a new bolt and nut per § 26-20.

B. Coning Hinge Friction Adjustment

1. Refer to Figure 26-6 and Table 26-1. Remove cotter pin, nut, thrust washer, and

cone blade to remove nut-side journal.

a. B370-1 Hub: Adjust coning hinge friction by changing trailing-edge shim

stack thickness in small increments; reducing shim stack thickness increases

friction, increasing shim stack thickness reduces friction. Coning hinge

friction is zero when there is a measurable axial gap per Figure 26-8. Install

shims, thrust washer, and nut.

b. A154-1 Hub: Adjust coning hinge friction by changing trailing-edge journal

length in small increments; using a shorter journal increases friction, using a

longer journal reduces friction. Coning hinge friction is zero when there is a

measurable axial gap per Figure 26-8. Install journal, thrust washer, and nut.

2. Install a new bolt and nut per § 26-20, steps 5 thru 7. Repeat steps for opposite

blade.

3. Check coning hinge friction by lifting blades until spindle tusks clear droop stops.

Hold one blade level and cone opposite blade. Rotor hub must not teeter as blade

is coned. Repeat check on opposite blade.

4. Using a feeler gage, measure gap between thrust washers and bearing faces at

coning hinge bolt head and nut. Verify 0.002-0.006 inch total gap per hinge.

5. Drill nut and bolt per § 26-34. Install a new cotter pin wet with epoxy primer.

Page 26.20

Chapter 26 Main Rotor

OCT 2018

26-33 Shifting the Main Rotor Hub

1. Remove cotter pin, nut, thrust washer, and nut-side A117 shims.

2. Have two people cone the main rotor blades. Push out teeter hinge bolt with another

bolt.

3. Move or exchange existing shims from one side of hub to the other as indicated by

main rotor balance chart (refer to § 10.230).

4. Install teeter hinge bolt per § 26-20.

26-34 Drilling Installed Main Rotor Hub Bolts

NOTE

Protect hub from damage due to chuck contact by wrapping

chuck and/or covering hub edge with several layers of tape.

New bolts and nuts must be installed and bolts stretched per § 23-33 prior to drilling.

Using a 0.125-inch diameter Cobalt twist-drill and cutting oil, drill a hole through nut and

bolt using an accessible pre-drilled hole in nut. The MT569-1 and MT569-6 (B370-1

hub coning hinge bolts) drill guide assembly will facilitate drilling a perpendicular hole. If

a pre-drilled hole is inaccessible, completely loosen nut, slightly rotate bolt to favorable

position, then special torque per § 23-33. Protect adjacent area from drilling debris.

OCT 2018

Chapter 26 Main Rotor

Page 26.21

26-40 Inspection of Main Rotor Blades

NOTE

Main rotor blades are 14 CFR § 27.602 critical parts. Notify RHC

Technical Support when voids exceeding the limits specified in

the instructions below are found, providing blade serial number,

helicopter serial number, time in service for the rotor blade, and

location and size of the voids that exceed the limits.

NOTE

The inspection criteria in this section applies to blade damage that

occurs after blade manufacturing (including shipping and handling

and time in service). Damage after blade manufacturing usually

exhibits paint scuffing, scratches, or freshly-exposed metal in

the form of scratches in the finish. If a blade manufacturing

irregularity is suspected, contact RHC Technical Support.

CAUTION

A blade may be repaired more than one time. However, in no

case can more than the maximum material be removed or the

maximum dent depth be exceeded in any one location.

A. Measuring Damage

1. Refer to Figure 26-10. Measure blade damage using a straight edge and a thickness

gage. Keep straight edge parallel with the leading and trailing edges.

2. If blades are installed on the helicopter, measure damage using the shortest straight

edge possible to span damaged area. Using a straight edge of excessive length will

cause a false reading due to natural droop of the blade.

B. Measuring Material Removed After Repair

1. Use calipers or micrometers and compare measurements before and after repair to

estimate amount of material removed.

2. Use a straight edge and thickness gage to measure repaired areas less than 2

inches across in the blade skins and spar.

26-41 Scratches and Corrosion on Blade Skins and Doublers

1. Refer to Figure 26-11. Damage may not exceed the following limits after rework:

A016-6 Blades:

a. 0.004 inch maximum depth for scratches more than 15º from spanwise axis.

b. 0.006 inch maximum depth for scratches less than 15º from spanwise axis.

A016-4 Blades:

a. 0.002 inch maximum depth for scratches more than 15º spanwise.

b. 0.003 inch maximum depth for scratches less than 15º spanwise.

2. Refer to § 26-50 for repair procedures for damage within limits. Polish out scratches

and corrosion greater than 0.0005 inch deep using a 0.10 inch blend radius.

OCT 2018

Chapter 26 Main Rotor

Page 26.23

26-42 Dents

CAUTION

Tap-test dented areas in honeycomb using an AN970-4 washer or

1965-or-later U.S. quarter dollar coin in good condition. If any voids

are found associated with dents, contact RHC Technical Support.

CAUTION

Do not repair any dent that has a sharp cut or break in the

skin; dent must have 0.060 inch minimum bottom radius. If

necessary, locally penetrant inspect, keeping penetrant materials

away from bond joints.

1. Refer to Figure 26-12. Damage may not exceed the following limits:

a. Honeycomb:

A016-6 Blades:

0.020 inch maximum bulge on opposite side of blade, opposite dent.

ii. 0.125 inch maximum depth dent between RS 127.0 and RS 151.1.

iii. 0.090 inch maximum depth dent between RS 75.5 and RS 127.0.

iv. 0.030 inch maximum depth dent between RS 10.4 and RS 75.5.

A016-4 Blades:

0.020 inch maximum bulge on opposite side of blade, opposite dent.

ii. 0.125 inch maximum depth dent between RS 130.30 and RS 151.1.

iii.0.090 inch maximum depth dent between RS 64.00 and RS 130.30.

iv. 0.030 inch maximum depth dent between RS 13.7 and RS 64.00.

b. Leading edge of doublers:

A016-6 Blades: 0.010 inch maximum depth dent.

c. Supported bond joints:

A016-6 Blades: 0.006 inch maximum depth dent.

A016-4 Blades: 0.002 inch maximum depth dent, tip cap only; refer to SB-103A.

d. Local deformations:

A016-6 Blades: Within 0.75 inch forward of trailing edge:

0.060 inch deformation between RS 30.0 and RS 151.0.

ii. 0.015 inch deformation between RS 10.4 and RS 30.0.

A016-4 Blades: Within 0.75 inch forward of trailing edge:

0.060 inch deformation between RS 30.00 and RS 151.00.

ii. 0.015 inch deformation between RS 13.70 and RS 30.00.

OCT 2018

Chapter 26 Main Rotor

Page 26.25

FIGURE 26-13 ROOT FITTING BLEND LIMITS

26-42 Dents (continued)

1. e. Spar: Refer to step 2. Blend damaged areas by hand with a minimum 1.0 inch

blend radius. Blending is not allowed within 0.010 inch of spar groove leading

edge.

A016-6 Blades:

0.020 inch maximum depth damage between RS 75.5 and RS 151.0.

ii. 0.010 inch maximum depth damage between RS 21.0 and RS 75.5.

A016-4 Blades:

0.020 inch maximum depth damage between RS 64.0 and RS 151.0.

ii. 0.010 inch maximum depth damage between RS 21.00 and RS 64.00.

2. Refer to § 26-50 for repair procedures for damage within limits. Smooth, round bottom

dents with 0.060 inch minimum radius may be filled and faired to an aerodynamic

shape.

Page 26.26

Chapter 26 Main Rotor

OCT 2018

26-43 Root Fitting Damage

1. Refer to Figure 26-13. Damage may not exceed the following limits:

A016-6 Blades:

Refer to step 2. Blend damaged areas by hand with a minimum 0.030 inch blend

radius.

a. 0.002 inch maximum depth blending on flange inboard face.

0.005 inch maximum depth, 0.250 inch maximum diameter blending on flange

outboard machined face (3 blends maximum).

0.10 inch minimum distance

from hole edges.

c. 0.040 inch maximum depth blending on exposed areas of root fitting.

A016-4 Blades:

Refer to step 2. Blend damaged areas by hand with a minimum 0.10 inch blend

radius.

a. 0.010 inch maximum depth blending on flange inboard face.

b. 0.005 inch maximum depth blending on 0.250 inch area outboard of flange.

c. 0.060 inch maximum depth blending on exposed areas of root fitting.

2. Refer to § 26-50 for repair procedures for damage within limits.

OCT 2018

Chapter 26 Main Rotor

Page 26.27

26-44 Voids

WARNING

Voids or debonds in rotor blades are not field repairable. Notify

RHC Technical Support when voids exceeding the limits specified

in the instructions below are found, providing blade serial number,

helicopter serial number, time in service for the rotor blade, and

location and size of the voids that exceed the limits.

CAUTION

Tap-test voids and debonds in blades using an AN970-4 washer

or 1965-or-later U.S. quarter dollar coin in good condition.

A. Critical Bond Areas

Refer to Figure 26-14. Critical bond areas are areas less than 0.50 inch spanwise

and less than 0.30 inch chordwise from the edge of any structural bond joint.

Bond areas not defined as semi-critical or non-critical are considered critical.

Voids separated by less than 0.25 inch are considered continuous.

1. Damage may not exceed the following limits:

a. 0.10 square inch maximum void.

b. Area must be at least 90% bonded.

B. Semi-Critical Bond Areas

A016-6 Blades:

A016-6 Blades do not have semi-critical bond areas.

A016-4 Blades:

Refer to Figure 26-14. Semi-critical bond areas are areas more than 0.50 inch

spanwise or more than 0.30 inch chordwise from the edge of the trim tab.

Voids separated by less than 0.25 inch are considered continuous.

1. Damage may not exceed the following limits:

a. 0.80 inch diameter circle maximum void.

b. 0.90 square inch maximum void.

c. 0.10 square inch maximum of a void extending into a critical bond area.

d. Area must be at least 80% bonded.

OCT 2018

Chapter 26 Main Rotor

Page 26.29

26-44 Voids (continued)

C. Non-Critical Bond Areas

Refer to Figure 26-14. Non-critical bond areas are areas more than 0.50 inch

spanwise or more than 0.30 inch chordwise from B440 cap (A016-4 blades), from

doubler edges, and from bonded areas between skin and honeycomb.

A016-6 Blades:

1. Voids in doubler bond joints separated by less than 0.25 inch are considered

continuous. Damage in doubler bond joints may not exceed the following limits:

a. Area must be at least 80% bonded.

b. 5.0 square inches, 1.0 inch chordwise, & 6.0 inches spanwise max. void.

c. 0.10 square inch maximum of a void extending into a critical bond area.

d. Voids are permissible within 0.30 inch of doubler leading edge where it

wraps around spar and root fitting.

2. Voids in honeycomb bond joints separated by less than 0.50 inch spanwise

or 1.0 inch chordwise are considered continuous. Damage in honeycomb

bond joints may not exceed the following limits:

a. Area must be at least 80% bonded.

8.0 square inches, 1.0 inches chordwise, & 20.0 inches spanwise

maximum void inboard of RS 92.0.

14.0 square inches, 2.0 inches chordwise, & 20.0 inches spanwise

maximum void outboard of RS 92.0.

A016-4 Blades:

1. Voids in A934 doubler bond joints may not exceed the following limits:

a. 5.0 square inches, 1.10 inches chordwise & 6.0 spanwise max. void.

b. 0.10 square inch maximum void extending into a critical bond area.

c. 2.0 inches maximum void from outboard tips (refer to R22 SL-55).

2. Voids in honeycomb bond joints inboard of RS 106.0 may not exceed 8.00

square inches, 1.00 inches chordwise, & 20.00 inches spanwise maximum.

3. Voids in honeycomb bond joints outboard of RS 106.0 may not exceed 14.00

square inches, 2.00 inches chordwise, & 20.00 inches spanwise maximum.

4. Voids in honeycomb bond joints between RS 120.0 and RS 133.5, and

between RS 150.0 and 166.0, must be at least 1.0 inch forward of

honeycomb trailing edge and the skin over void may not move when trim

tabs are flexed.

5. Voids in A934 doubler bond joints separated by less than 0.25 inch, less

than 0.50 inch spanwise, or less than 1.0 inch chordwise are considered

continuous. Area must be at least 80% bonded.

Page 26.30

Chapter 26 Main Rotor

OCT 2018

26-50 Repair of Main Rotor Blades

WARNING

Unauthorized repairs to rotor blades have caused fatal crashes.

CAUTION

Do NOT use power tools or chemical paint strippers to repair

main rotor blades.

NOTE

Refer to § 23-70 for approved materials.

Measure damage per § 26-40.

Remove damage at trailing edges, trim tab edges, tip cap, and/or tip corner by trimming

per § 26-51 as required.

Polish out damage using 220 grit or finer wet-or-dry aluminum-oxide abrasive paper,

and finish with 320 grit or finer wet-or-dry abrasive paper. A fine-toothed file may

be used along the spar and trailing edge, provided the area is finished with 320 grit

or finer wet-or-dry abrasive paper. Sand or file in spanwise direction. Remove only

the material necessary to remove the damage and blend to the radius or dimension

specified. Maintain squareness of trailing edge per Figure 26-16. Visually inspect and

verify damage is removed.

Measure material removed per § 26-40. Verify repair does not exceed limit specified.

Seal or fill as required per the following:

a. Clean area to be sealed or filled using approved solvent (refer to § 23-70).

b. Apply epoxy primer to bond joints with pin holes or other openings. Mix primer

per manufacturer’s instructions. Allow a minimum of 24 hours cure time.

c. Using 220-grit or finer wet-or-dry aluminum-oxide or silicon-carbide abrasive

paper, hand-sand cured adhesive in spanwise direction to a smooth, aerodynamic

finish, congruent with the blade airfoil. Do not remove metal.

d. Hand-sand surrounding painted surface until 25% primer remains. Keep bare

metal to a minimum.

Paint per § 26-52 as required.

Track and balance main rotor per § 10.230 as required.

OCT 2018

Chapter 26 Main Rotor

Page 26.31

FIGURE 26-16 SANDING/FILING SKIN EDGES SQUARE

26-51 Trimming

Refer to Figures 26-15 & 26-16. Trimming may be performed on the trailing edge of main

rotor blade skins and trim tab edges within limits shown. (Alternately, a trailing edge

nick or notch may be blended out 1.0 inch minimum spanwise, each side of nick or notch

within limits shown.) Trimming is not permitted on spar or doublers.

Tip cap and tip corner may be trimmed within limits shown.

Finish repair per § 26-50 steps 2 thru 7. File trailing edge or trim tab edges square with

skins (do not file into a point). Verify minimum chord dimension.

26-52 Painting

Refer to § 23-70 for approved materials. Refer to paint manufacturer’s recommendations.

CAUTION

If force-drying paint, do not exceed 175º F surface temperature

on blade; monitor blade temperature.

1. Remove main rotor blade tip cover(s) as required. Clean the blade(s).

2. Feather edge of paint bordering bare metal by hand-sanding spanwise with 220-grit or

finer wet-or-dry aluminum-oxide or silicon-carbide abrasive paper. Do not remove metal.

3. Mask area to prevent overspray contamination.

4. Clean bare metal to be painted with a lint-free cloth dampened with enamel cleaner.

5. Prime bare metal, including bare metal under tip cover(s) as required, with at least

two coats epoxy primer. Scuff first coat of primer with 320-grit abrasive paper (or

very fine Scotch-Brite), and wipe down with a lint-free cloth dampened with enamel

cleaner prior to applying second coat.

OCT 2018

Chapter 26 Main Rotor

Page 26.33

CHAPTER 33

ELECTRICAL SYSTEM

Section

Title

Page

33-00

Description

33.1

33-10

Battery

33.2

33-20

Clutch Actuator

33.3

33-30

Lighting System

33.3

33-40

Audio System

33.4

33-50

Dual Tachometer

33.5

33-60

Warning and Caution Lights

33.7

33-70

Carbon Monoxide Detector

33.8

33-80

Emergency Locator Transmitter (ELT)

33.9

33-90

Low Rotor RPM Warning System

33.9

33-100 Alternator Output Voltage Adjustment without A942-1

33.10

33-110 Troubleshooting

33.10

33-120 Electrical Load Analysis

33.20

OCT 2018

Chapter 33 Electrical System

Page 33.i

CHAPTER 33

ELECTRICAL SYSTEM

33-00 Description

CAUTION

The installation of electrical devices can affect the accuracy

and reliability of the electronic tachometer.

A 14-volt DC electrical system which includes an alternator and a sealed lead-acid battery

is standard. The battery is located either in the engine compartment or beneath the

instrument console.

The circuit breaker panel is on the ledge just forward of the left seat. Breakers are marked

to indicate function and amperage and are of the push-to-reset type.

The battery switch controls the battery relay which disconnects the battery from the

electrical system. A wire protected by a fuse near the battery bypasses the battery relay

to allow both tachometers and the clock to continue to receive battery power with the

battery switch off.

The alternator control unit protects the electrical system from overvoltage conditions. The

ammeter indicates current to the battery (“-” indicates discharge). An ALT caution light or

ammeter discharge indication in flight indicates low voltage and possible alternator failure.

NOTE

Except for emergency procedures, do not operate alternator

with battery switched off. The battery helps protect electrical

equipment from voltage spikes.

Later aircraft have an avionics master switch which controls power to the avionics bus.

This allows all avionics to be switched on and off by a single switch.

OCT 2018

Chapter 33 Electrical System

Page 33.1

33-10 Battery

NOTE

Refer to Concorde Battery Corporation's Owner/Operator's

Manual, and Instruction for Continued Airworthiness for battery

maintenance procedures.

CAUTION

To minimize risk of electrical discharge: When disconnecting

battery, disconnect negative (ground) cable from battery first,

then the positive cable. When connecting battery, connect

positive cable to battery first, then the negative (ground) cable.

A. Disconnecting and Removing Battery

1. Turn battery switch off.

a. Aft Battery: Remove engine left side skirt, as required. Remove cotter

rings and wing nuts to release rods attaching battery box assembly to lower

frames. Remove cover.

b. Nose battery: Open upper console and remove battery box cover.

2. Remove hardware securing negative (ground) cable to battery negative terminal.

3. Remove hardware securing positive cable to battery positive terminal. Carefully

remove battery.

B. Installing and Connecting Battery

1. Turn battery switch off.

2. Position battery in battery box and connect battery cables. Special torque terminal

bolts as noted on battery label and torque stripe per Figure 2-1.

3. Install cover.

a. Aft Battery: Install wing nuts and cotter rings to secure rods attaching

battery box assembly to lower frames. Verify security. Install engine left

side skirt, if removed.

b. Nose battery: Secure upper console.

Page 33.2

Chapter 33 Electrical System

OCT 2018

33-20 Clutch Actuator

After the engine is started, it is coupled to the rotor drive system through vee-belts which

are tensioned by raising the upper drive sheave. An electric actuator, located between

the drive sheaves, raises the upper sheave when the pilot engages the clutch switch. The

actuator senses compressive load (belt tension) and switches off when the vee-belts are

properly tensioned. The clutch caution light illuminates whenever the actuator circuit is

energized, either engaging, disengaging, or re-tensioning the belts. The light stays on until

the belts are properly tensioned or completely disengaged.

Belt slack during engine start should be adjusted such that blades begin turning within five

seconds of clutch engagement. Excessive slack may cause belts to jump out of sheave

grooves during start. Periodic readjustment by a mechanic may be required as belts wear

in service.

A fuse located on or near the test switch panel prevents an actuator motor overload from

tripping the circuit breaker. If the fuse blows, the actuator motor will stop but the clutch

caution light will remain illuminated. An open circuit breaker removes power from both the

motor and the light. With an open circuit breaker, no belt tensioning will occur, and the

light will not function to indicate an abnormal condition.

CAUTION

Never take off while clutch caution light is on.

33-30 Lighting System

A red anti-collision light is installed on the tailcone and is controlled by the strobe switch.

Position lights are installed on each side of the cabin and in the tail and are controlled by

the nav lights switch. Post and internal lights (earlier aircraft) or a light at the top of the

windshield (later aircraft) illuminate the instruments. Instrument lighting is active when the

nav lights switch is on and lighting is dimmed via the knob above the nav lights switch.

An overhead map light mounted on a swivel is controlled by an adjacent switch. The map

light may be used for emergency lighting of the instrument panel.

Two landing lights are installed in the nose at different vertical angles to increase the lighted

area. One landing light switch controls both lights and is located on the cyclic center post.

NOTE

Landing lights operate only when clutch actuator switch is in

the engage position.

NOTE

Continuous operation of landing and position lights in flight is

recommended to promote collision avoidance.

OCT 2018

Chapter 33 Electrical System

Page 33.3

33-40 Audio System

A voice-activated intercom/audio system is standard and is controlled by a small control

panel above the avionics stack. The ICS volume knob controls intercom volume but does

not affect radio volume. The VOX squelch knob is used to set the threshold volume at

which the intercom is activated. When the VOX knob is turned fully clockwise, keying

is required to activate the intercom. Later intercom systems include a music input jack

located on the circuit breaker panel. This input is muted when the intercom is active, when

transmitting, and during reception of radio signals.

Headset jacks are located in the ceiling near each seat. The cyclic grips are equipped

with either transmit and intercom buttons or trigger-style intercom/transmit switches. For

the trigger-style switch, the first detent activates the intercom and the second detent

transmits. An additional intercom button is located on the left-hand floor or seat support.

Earlier R22s are equipped with an intercom system that operates in either push-to-talk

(PTT) or hot mic modes. A toggle switch to the left of the cyclic center post is used to

change modes. In PTT mode, the intercom is activated using the intercom buttons.

Audio control panels from several manufacturers are offered as options in place of the

standard intercom system. Pilots should consult the manufacturer’s operating instructions

if an audio panel is installed.

Page 33.4

Chapter 33 Electrical System

OCT 2018

33-50 Dual Tachometer

An electronic engine and rotor dual tachometer is standard. Engine tachometer signal is

provided by magneto breaker points. Rotor tachometer signal is provided by two magnetic

senders at the main gearbox drive yoke. Each tachometer is on a separate circuit with its

own circuit breaker. With battery and alternator switches off, the tachometers continue

to receive power from the battery through a bypass circuit as long as the clutch actuator

switch is in the engage position.

NOTE

Do not stow helicopter with clutch switch engaged. The

tachometers are powered with the clutch engaged and will

discharge the battery.

A. Adjustment

1. The early model A792-1 Dual Tachometer is pre-set at the factory and is not

adjustable in the field. For repair or adjustment, the unit must be returned to

Robinson Helicopter. (No adjustment screw on early models.)

2. The A792-2 Dual Tachometer is pre-set at the factory. Slight variations between

rotorcraft may require readjustment of rotor side of tachometer. To adjust

tachometer:

a. Remove screws that fasten instrument face panel to upper console and

carefully pull panel aft.

b. Ground run helicopter at 104% indication on the engine tachometer. Adjust

the rotor tachometer to read 104%. On back of tachometer, turn the

adjustment screw clockwise to increase and counter-clockwise to decrease

rotor tachometer indication (1/8 turn changes indication approximate 1%).

c. Reinstall instrument panel.

d. If tachometer cannot be adjusted, replace or return to Robinson Helicopter

Company for repair.

OCT 2018

Chapter 33 Electrical System

Page 33.5

33-60 Warning and Caution Lights

Warning and caution lights include clutch, main gearbox over-temperature, main and tail

gearbox chip, starter on (later aircraft), low fuel, low RPM, alternator, low oil pressure,

rotor brake, governor off, carbon monoxide (aircraft with cabin heater), and full throttle

(later aircraft). The clutch light indicates that the clutch actuator is operating. The low

RPM light and horn indicate rotor RPM at 97% or below. The low oil pressure and low fuel

lights are actuated by sensors in those systems and are independent of the gage indicators.

The alternator light warns of a possible alternator failure. The governor-off light indicates

the RPM governor is switched off.

The main and tail gearbox chip detectors are magnetic devices located in the drain plug of

each gearbox. When metallic particles are drawn to the magnets they close an electrical

circuit, illuminating the caution light. Metal particles may be caused by a failing bearing or

gear, thus giving warning of impending gearbox failure. The main gearbox over-temp light

is actuated by a temperature switch located near the input pinion.

The carbon monoxide light is actuated by a sensor above the pilot’s heater outlet and

indicates elevated cab in carbon monoxide levels.

The full throttle light is activated by a switch in the throttle linkage and indicates that the

engine is near full throttle.

A. Full Throttle Caution Light

1. Rigging Check

a. Turn fuel shut-off valve off.

b. Turn battery switch on. Raise collective full up and slowly rotate twist grip

open until full throttle caution light just illuminates.

c. Refer to Figure 33-1. Verify gap from throttle stop to corner of throttle body

full-throttle stop is 0.114-0.148 inch. Adjust as required per step 2.

d. Lower collective & turn battery switch off. Turn fuel shut-off valve on.

2. Switch Adjustment

a. Refer to Figure 33-1. Raise collective full up, rotate (throttle) twist grip

as required, loosen screw, and pivot A607-2 slotted cam (in throttle

linkage, under co-pilot seat) so V3-1 switch activates when throttle stop

is approximately 0.130 inch from corner of throttle body full-throttle stop.

Tighten screw.

b. Perform rigging check per step 1.

OCT 2018

Chapter 33 Electrical System

Page 33.7

33-70 Carbon Monoxide Detector

The carbon monoxide (CO) detector, if installed, indicates elevated cabin CO levels. CO is

an odorless, toxic gas present in engine exhaust which causes headaches, drowsiness, and

possible loss of consciousness. CO levels may become elevated due to an exhaust leak or

exhaust recirculation during prolonged hovering.

The CO detector system consists of a sensor above the pilot’s heater outlet and a caution

light. A system check (light flashes twice) is performed each time power is switched on.

A sensor malfunction is indicated by a continuing flash every four seconds.

If the caution light illuminates, shut off heater and open nose and door vents as required

to ventilate the cabin. If hovering, land or transition to forward flight. If symptoms of CO

poisoning (headache, drowsiness, dizziness) accompany caution light, land immediately.

Have exhaust system inspected before next flight.

Many chemicals can damage the CO sensor. Avoid use of solvents, detergents, or aerosol

sprays near the sensor. Temporarily tape off openings in top and bottom of sensor housing

when cleaning cabin interior.

Page 33.8

Chapter 33 Electrical System

OCT 2018

33-80 Emergency Locator Transmitter (ELT)

The Emergency Locator Transmitter (ELT) installation consists of a transmitter with internal

battery pack, an external antenna, and a remote switch/annunciator. The transmitter is

mounted to the upper steel tube frame and is accessible through the aft, upper cowl door.

The remote switch/annunciator is located left of the cyclic stick.

The ELT is operated by a switch on the transmitter and a remote switch in the cockpit. The

transmitter switch has been secured in the AUTO or ARM position at installation and should

always be in this position for flight. The remote switch/annunciator is a three position

switch with indicator light. This switch should also be in the AUTO or ARMED (middle)

position for flight. With both switches set to AUTO/ARM, the ELT will begin transmitting

when subjected to a high “G” load. When the unit is transmitting, the red indicator light

illuminates.

Moving the remote switch to ON activates the transmitter. Use the ON position if an

emergency landing is imminent and time permits.

If the ELT is inadvertently activated, use the RESET position of the remote switch to stop

transmission and reset the unit. The red indicator will extinguish when unit is reset.

NOTE

Earlier aircraft may have ELT installations without remote

switch.

For more detailed instructions on ELT operation, maintenance, and required tests, refer to

manufacturer’s instructions supplied with the unit.

33-90 Low Rotor RPM Warning System

A. Horn Adjustment

When the collective is raised 0.2 to 0.4 inches (measured at grip) above fully down, the

low-rotor RPM warning unit must activate the low-rpm warning horn and low-rpm light

at 97% to 96% rotor RPM; horn and light must turn off above 96% to 97% rotor RPM.

The low rotor RPM warning unit is inside the upper console mounted on the left

vertical panel. Some older helicopters may mount the unit on the right side, or

ty-rapped to upper console’s main wire bundle. Adjustments are made by turning an

exposed screw on warning unit, accessible by removing a black-plastic plug from a

3/8-inch diameter hole on the left vertical panel. The A569-1 warning unit’s (potted

circuit board type) adjustment screw sensitivity is approximately 1/16 turn per 1%

change. The A569-5 warning unit’s (metal box type) adjustment screw sensitivity is

approximately 2 turns per 1% change. If warning unit cannot be adjusted to above

values it must be replaced.

OCT 2018

Chapter 33 Electrical System

Page 33.9

33-100 Alternator Output Voltage Adjustment without A942-1

To check or adjust the output voltage:

1. Connect a voltmeter to “I” terminal of voltage regulator and ground with helicopter

running and read voltage (13.2 to 13.8 volts).

2. Output voltage may be adjusted using range screw on voltage regulator.

33-110 Troubleshooting

A. A569-5 Low Rotor RPM Warning Unit

Perform following tests prior to replacing A569-5 low rotor-rpm warning unit:

Verify:

a. Low RPM light bulb is functional.

b. Master switch off.

c. Full-down collective.

d. Horn circuit breaker in.

Access and disconnect both horn and A569-5 low rotor-rpm warning unit from

airframe electrical wiring.

Turn Master switch on and verify Horn circuit breaker remains in. If Horn circuit

breaker pops then -70 wire is shorted to ground; repair as required. Turn Master

switch off.

On the warning unit’s airframe electrical connector, install a jumper between

wires -70 & -75.

Turn Master switch on and verify Horn Start circuit breaker remains in. If Horn

Start circuit breaker pops then a short-to-ground exists in -75 wire and/or collective

activated V3-1 switch; repair as required.

Fully raise collective and verify Horn Start circuit breaker remains in and Low

RPM light illuminates. If Horn Start circuit breaker pops then a short-to-ground

exists in -76 wire and/or -78 wire and/or collective-activated V3-1 switch; repair

as required. If Low RPM light does not illuminate then collective-activated V3-1

switch is faulty or mis-adjusted and/or an open exists in -70, -75, or -76 wires.

Slowly raise and lower collective fully several times while simultaneously

manipulating throttle. Verify Horn Start circuit breaker remains in and Low RPM

light remains illuminated whenever collective is raised. If Horn Start circuit breaker

pops then a short-to-ground condition is occurring in -70, -75, or -76 wires and/or

collective-activated V3-1 switch due to collective movement. Check for pinched/

rubbing wiring and repair as required.

Turn Master switch off. Connect horn to airframe wiring.

Page 33.10

Chapter 33 Electrical System

OCT 2018

33-110 Troubleshooting (continued)

A. A569-5 Low Rotor RPM Warning Unit (continued)

Turn Master switch on. Raise collective and verify horn activates and has

consistent tone. If Horn Start circuit breaker pops then horn is faulty and/or -78

wire is shorted to ground; repair as required. If horn fails to activate then -79

wire is open or horn is faulty; repair as required. If tone is inconsistent then horn

is faulty and/or poor connections exist; repair as required.

10.

If A569-5 warning unit has starter lockout circuit enabled (warning unit’s 9-pin

connector plugged into airframe harness), also perform following steps:

11.

Check A999-1 master radio relay current draw:

a. Master switch off and belt tension actuator fully disengaged.

b. Disconnect A569-5 low-rpm warning unit’s 9-pin connector and place an

ammeter in series (positive lead on pin 7) between pins 7 and 8 on airframe

side of connector.

c. Master switch on, Horn Start and Clutch Start circuit breakers in, avionics

off, rotor brake released, mixture at idle cut-off.

d. Select key switch to Start position and crank engine. Note and record

current draw at ammeter while cranking engine. Select key switch to Off

position.

e. Disconnect 582 wire at tab on starter solenoid and isolate connector (do not

let it ground). Select key switch to Start position. Note and record current

draw at ammeter; current should be 94-156 milliamps and a buzzing sound

should be heard from the starter vibrator. Select key switch to Off position.

12.

Check starter circuit:

a. Master switch off and belt tension actuator fully disengaged.

b. Disconnect A569-5 low-rpm warning unit’s 9-pin connector and jump pins 7

and 8 on airframe side of connector.

c. Master switch on, Horn Start and Clutch Start circuit breakers in, rotor brake

released, mixture at idle cut-off.

d. Select key switch to Start position and crank engine. If engine does not

crank there is a problem in the starter circuit. If engine cranks then there is

a problem in either the A569-5 unit or the sense circuit.

OCT 2018

Chapter 33 Electrical System

Page 33.11

33-110 Troubleshooting (continued)

A. A569-5 Low Rotor RPM Warning Unit (continued)

13. Check A596-5 sense circuit:

a. Master Switch on.

b. Momentarily engage clutch and verify Clutch light illuminates then disengage

clutch completely.

c. Master switch off.

d. Disconnect A051-1 actuator’s black four-pin connector. Ground airframe-

side plug’s pin 1 thru a #330 (post light type) lamp.

CAUTION

Failure to ground pin 1 thru a #330 lamp (such as direct

grounding) may result in wiring damage.

e. Verify less than 200 ohms (20 ohm nominal) to ground at pin 4 and at pin 5

on ship side of A569-5’s 9-pin connector.

f. Master switch on.

g. With A569-5 unit connected to airframe harness, verify voltage does not

exceed 0.5V from pin 4 to ground and from pin 5 to ground.

h. Master switch on, Horn Start and Clutch Start circuit breakers in, rotor brake

released, mixture at idle cut-off.

i. Select key switch to Start position and crank engine. Failure of engine to

crank indicates problem in A569-5 unit.

14. Upon successful completion of preceding tests the A569-5 low rotor-rpm warning

unit may be replaced and adjusted per § 33-90.

Page 33.12

Chapter 33 Electrical System

OCT 2018

33-110 Troubleshooting (continued)

B. General

TROUBLE

PROBABLE CAUSE

CORRECTION

No electrical

Battery terminals corroded

Clean terminals.

power

Bad or no ground

Clean ground path.

Tripped circuit breaker

Check circuit, if circuit checks ok, reset

circuit breaker.

Low battery voltage

Check battery. Recharge if necessary.

Low or no alternator output

Check alternator belt tension, wiring, and

alternator control unit.

Bad wire or terminal

Replace.

Engine cranks

Low battery voltage

Service or replace battery.

slowly, but will

not start

Insufficient drive belt deflection

Adjust actuator down-limit screw.

Corroded or dirty battery or starter

Clean terminals.

terminals

Bad starter relay, wires or terminals

Replace defective parts.

Engine cranks

Bad ignition switch

Replace switch.

but will not start

Bad starting vibrator

Repair or replace vibrator.

Incorrect retard timing

Adjust retard magneto internal timing.

Starter fails to

Rotor brake engaged

Release rotor brake.

operate

Low battery charge

Check and recharge if necessary.

Circuit breakers tripped

Reset both HORN START and CLUTCH

START circuit breakers.

Actuator not fully disengaged

Engage actuator momentarily, then fully

disengage.

Loose connections

Check all wiring (refer to wiring diagram).

Defective wiring

Check all wiring (refer to wiring diagram).

Starter motor - burned winding or

Repair or replace starter.

bad brushes

OCT 2018

Chapter 33 Electrical System

Page 33.13

33-110 Troubleshooting (continued)

B. General (continued)

TROUBLE

PROBABLE CAUSE

CORRECTION

Discharged battery

Battery worn out

Replace

Charging rate not set correctly

Reset

Standing too long

Remove and recharge battery

Equipment left on accidentally

Remove and recharge battery

Starter - Low cranking speed

Same electrical causes as listed

Same remedies as listed under

under “starter fails to operate”

”starter fails to operate”

Battery life is short

Impurities in electrolyte

Replace battery

Low charging rate

Adjust voltage regulator

Battery runs out of electrolyte

Too much water added to battery

Drain and keep battery at proper

and charging rate too high

level and adjust voltage regulator

Excessive corrosion inside

Spillage from overfilling

Use care in adding water

container

Vent lines leaking or clogged

Repair or clean

Charging rate too high

Adjust voltage regulator

Battery consumes excessive

Charging rate too high (if in all

Correct charging rate

water

cells)

Alternator fails to supply

Alternator defective

Replace

charging current with engine

operating

Voltage regulator defective

Replace

Overvoltage relay defective

Replace

Alternator switch defective

Replace

Page 33.14

Chapter 33 Electrical System

OCT 2018

Robinson R22 Helicopter. MAINTENANCE MANUAL (2018) - page 7