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13-39. Inspection - Lower Plenum
A. Inspect the lower plenum for cracks, damage, cleanliness, condition and security of
mounting brackets, condition and security of the protective shield, and differential air pressure
line fitting for condition and security. Ensure the drain holes are open and clean.
B. Inspect the bell mouth inlet for cleanliness and cracks.
C. Check the bell mouth inlet seal for condition and loose bonding.
13-40. Repair - Lower Plenum
A. Repair damage to the lower plenum I/A/W AC 43.13-1B.
B. Bond the mounting brackets and the air line fitting to the lower plenum using acrylic
adhesive (Magnacryl Brand # 506).
C. Replace the mounting brackets if not repairable.
D. Replace the protective shield double back adhesive tape as required.
E. Replace the bell mouth inlet if cracked.
F. Replace bell mouth inlet seal if worn or damaged. Use the following procedure to
replace the seal.
G. Bond the seal to the bell mouth inlet as follows:
WARNING
Methylethylketone (MEK) is toxic and must be used with extreme caution.
Make sure adequate ventilation is provided. Repeated or prolonged contact
with the skin should be avoided. Low-volatile substitutes, such as Extreme
Simple Green or Citra-Safe, are preferred solvents.
(1) Remove the existing seal and clean the bond surface on the bell mouth inlet with
Extreme Simple Green, or equivalent. Lightly abrade the bond surface with 220
grit sandpaper or equivalent. Repeat cleaning the bond surface.
(2) Apply a coat of EC776 3M™ Adhesive or equivalent to the bell mouth bond
surface and to the seal bond surface. Allow the adhesive to dry until no longer
tacky (approximately 30 minutes). Apply a second coat of adhesive and allow to
dry until no longer tacky.
(3) Revive the adhesive on both bond surfaces with Extreme Simple Green, or
equivalent, and carefully fit the seal onto the bell mouth. Apply weighted uniform
pressure to ensure a good bond and allow two (2) hours curing time before
reinstalling the bell mouth inlet. Allow twenty four (24) hours curing time before
using the aircraft.
Rev. 25
MM-13-23
Aug 22/16
13-41. Installation - Lower Plenum
CAUTION
Care must be used to prevent damage to the lower plenum during installation.
A. Install the plenum in the airframe by reversing the removal procedure (paragraph 13-
38).
B. Install the mounting hardware but do not tighten at this time.
CAUTION
Remove the cover from the engine inlet and perform a visual inspection of the
inlet before installing the bell mouth inlet.
C. Install the bell mouth inlet through the left side inlet of the plenum. Attach the inlet to
the engine and torque the hardware to 10-15 in-lbs/1.1-1.7 Nm.
D. Position the plenum so a good seal is formed between the plenum and the bell mouth
inlet, tighten the mounting hardware.
(1) Install spacers (Figure 13-1, 18), as required, between the tab on the pylon and
the plenum attachment bracket to ensure contact between the plenum and the
bellmouth seal.
E. Connect the differential pressure air line to the plenum fitting. Torque 7-10 in-lb/0.8-
1.0 Nm.
F. Connect the engine wash line to the plenum fitting.
G. If removed, install the upper plenum (para. 13-31).
H. Install the transfer ducts (para. 13-26).
I.
Install the cowling mounting bracket.
J. Install the eductor.
H. Install bottom aft cowling.
13-42. Scavenge Air Lines
13-43. Removal - Scavenge Air Lines
A. Remove the left and right aft side cowlings.
B. Remove the eductor (para. 13-11).
CAUTION
Use a backing wrench when loosening or tightening air/fluid lines and fittings
to prevent damage to the lines or fittings.
Rev. 26
MM-13-24
Feb 28/2020
13-128. Tachometer Generator
13-129. Removal - Tachometer Generator
NOTE
The procedures for removal, inspection, and installation are the same for both
the N1 and N2 tach generators.
A. Disconnect the electrical led from the tach generator.
B. Remove the nuts and washers securing the tach generator. Remove the tach
generator and gasket.
13-130. Inspection - Tachometer Generator
A. Inspect the tach generator for cracks, corrosion, seal leakage, dents, and security.
B. Inspect the electrical connector for corrosion and condition.
13-131. Repair - Tachometer Generator
A. Replace the tachometer generator if inoperable or damage effects the proper
operation of the tachometer generator.
B. Replace the gasket and the tachometer pad seal (Rolls-Royce 250-C20 Series
Operation and Maintenance Manual) if oil leakage is evident.
13-132. Installation - Tachometer Generator
NOTE
Replace all used o-rings/packings and gaskets.
NOTE
Refer to the TH-28/480 Series Illustrated Parts Catalog to determine the
correct N2 tach generator for the dual tachometer (N2/NR) installed in the
instrument panel.
A. Install the tach generator and gasket.
B. Install the electrical lead and safety wire.
13-133. Engine Mounts
13-134. Removal - Engine Mounts
A.
Remove the hardware securing the mount and remove the mount.
Rev. 6
MM-13-71
Apr 16/07
13-135. Inspection - Engine Mounts
A. Inspect the engine mounts for cracks, corrosion, bends, elongated holes, damaged
threads, and security of installation. (See also SDB T-038, latest revision.)
13-136. Repair - Engine Mounts
A. Replace engine mounts that are cracked, bent, have elongated bolt holes, or thread
damage that cannot be repaired.
B. Remove minor nicks, scratches, corrosion, or thread damage.
13-137. Installation - Engine Mounts
A. Install the mounts.
CAUTION
The top mount torque requirement is applicable to the three bolts (Figure 13-9,
Item 40) used to secure the top engine mount to the engine. This torque
requirement does not apply to the pylon mount nut and jam nut (Figure 13-9, Item
42) used to secure the engine to the pylon. Refer to paragraph 13-7, C, E, for the
correct pylon mount nut and jam nut tightening procedure.
1)
Top mount: torque the hardware to 110 in-lbs/12.5 Nm and lockwire (.032).
2)
Side mounts: install the self-locking engine mount bolt, torque hardware to 110
in-lb/12.5 Nm, and apply a thin line of white paint (Torque Seal, or equivalent) on
the head of the bolt and engine mount.
13-138. Fuel Filter Differential Pressure Switch
13-139. Removal - Fuel Filter Differential Pressure Switch
CAUTION
If the pressure switch is being removed from an engine installed in an aircraft,
pull the fuel shutoff valve to the OFF position.
A. Disconnect the electrical lead from the switch.
CAUTION
Cap or plug all open fluid/air fittings to prevent contamination of the engine.
CAUTION
Use a backing wrench to prevent damaging fluid/air lines and fittings.
B. Remove the lines connecting the switch to the fuel pump housing.
Rev. 26
MM-13-72
Feb 28/2020
C. Remove the nut securing the pressure switch and clamp to the accessory gearbox.
Remove the pressure switch.
D. Remove the fittings from the pressure switch and from the fuel pump housing.
13-140. Inspection - Fuel Filter Differential Pressure Switch
A. Inspect the pressure switch for cracks, corrosion, damage, leaks, and security.
B. Inspect the lines and fittings for bends, cracks, corrosion, damaged threads, leaks,
nicks, scratches, and security.
C. Inspect the electrical connector for condition and corrosion.
13-141. Repair - Fuel Filter Differential Pressure Switch
A. Replace the pressure switch if cracked, inoperative, damage to the electrical
connector cannot be repaired, or fuel leakage is evident from the switch.
B. Replace lines that are bent, cracked, or have damage to the flares that cannot be
polished out. Remove minor nicks, scratches, or corrosion.
C. Replace fittings that have damage to the threads that effect the operation and
security of installation for the system or damage to the flares that cannot be polished out.
D. Replace o-rings that are leaking.
13-142. Installation - Fuel Filter Differential Pressure Switch
NOTE
Replace all used o-rings/packings and gaskets.
CAUTION
Use a backing wrench to prevent damaging fluid/air lines and fittings.
A. Install the fittings in the pressure switch and the BF and AF ports of the fuel pump
housing.
B. Install the pressure switch into the mounting clamp and attach to the accessory
gearbox. Torque the nut to 35-40 in-lbs/4.0-4.5 Nm.
C. Install the lines between the fuel pump housing and the pressure switch.
D. Connect the electrical lead to the pressure switch.
Rev. 26
MM-13-73
Feb 28/2020
13-143. Customer Bleed Air Lines and Fitting
13-144. Removal - Customer Bleed Air Lines and Fittings
CAUTION
Use a backing wrench to prevent damaging fluid/air lines and fittings.
CAUTION
Cap or plug all open fluid/air fittings to prevent contamination of the engine.
A. Remove the lines connected to the customer bleed air fittings on the compressor
scroll.
B. Remove the customer bleed air fittings from the compressor scroll.
13-145. Inspection - Customer Bleed Air Lines and Fittings
A. Inspect the lines and fittings for bends, cracks, corrosion, damaged threads, nicks,
scratches, and security of installation.
13-146. Repair - Customer Bleed Air Lines and Fittings
A. Replace lines that are bent, cracked, or have damage to the flares that cannot be
polished out. Remove minor nicks, scratches, or corrosion.
B. Replace fittings that have damage to the threads that effect the operation and
security of installation for the system or damage to the flares that cannot be polished out.
13-147. Installation - Customer Bleed Air Lines and Fittings
NOTE
Replace all used o-ring/packings and gaskets.
A. Apply anti-seize (MIL-PRF-907) to the threads of the customer bleed air fittings and
install the customer bleed air fittings in the compressor scroll.
B. Install and connect the customer bleed air lines to the fittings in the compressor scroll.
Rev. 26
MM-13-74
Feb 28/2020
13-148. Consumable Materials List
ITEMS
DESCRIPTION
PART NUMBER
Adhesive
Acrylic Adhesive, IPS Corporation
WELD-ON 45
Adhesive
Acrylic Adhesive, Magnacryl Brand1
506 with accelerator (#7)
Adhesive
Structural Adhesive, Loctite Brand
EA 9359.3 AERO
Adhesive
Structural Adhesive, Loctite Brand
Loctite H3300
Indicator Paste
Cross-Check™ Torque Seal, Dykem
88314 through 88321
Brand
(color options)
Inspection Seal
Torque Seal
F-900
Lacquer
Lockwire
Lockwire, .020"
MS20995C20
Lockwire
Lockwire, .032"
MS20995C32
Lubricant
Anti-Seize
MIL-PRF-907
O-ring
O-ring (Oil Reservoir Drain Plug)
MS28778-6
Primer
Loctite 7649
19269
Sealant
Clear Silicone Sealant, Dow Corning
732 RTV
Brand
Solvent
Citra-Safe, Inland Technology
6850-01-378-( )
Incorporated
Solvent
Extreme Simple Green, Sunshine
13440
Makers, Inc.
Thread sealant
Thread sealant, Loctite Brand (222)
21463, 38653
Thread sealant
Thread sealant, Loctite Brand (277)
27731
Thread sealant
Thread sealant, Loctite Brand
24200
Threadlocker Blue 2422
Thread sealant
Thread sealant, Vibra-Tite Brand
Vibra-Tite VC-3
1 Trade names Versilok 506 or Hughson 506 are identical to Magnacryl 506.
2 Acceptable alternate where thread sealant is required.
Rev. 26
MM-13-75
Feb 28/2020
INTENTIONALLY LEFT BLANK
Rev. 17
MM-13-76
Jun 24/11
14-97. Engine Flush Kit
14-98. Description - Engine Flush Kit
An optional engine flush kit is available for the TH-28, 480, and 480B. The kit consists of
a nozzle installed in the lower plenum assembly, a bulkhead connector for attachment of the
flush can, and the line that connects the nozzle to the bulkhead. Refer to the Rolls-Royce 250-
C20 Operation and Maintenance Manual for the proper maintenance procedures for flushing the
engine.
14-99. Removal - Engine Flush Kit
A. Open the left side engine access panel and remove the aft bottom cowling.
B. Disconnect the line from the bulkhead fitting located on the cowl ring and from the
nozzle located in the aft side of the lower plenum assembly.
C. Remove the bulkhead fitting from the cowl ring.
NOTE
The nozzle is installed in the lower plenum with adhesive and rivets and is not
normally removed.
D. Install a cap on the nozzle.
14-100. Inspection - Engine Flush Kit
A. Inspect the flush kit for damage and security of installation.
14-101. Repair - Engine Flush Kit
A. Replace the flush kit line if damage causes the line to be unserviceable.
B. Replace the bulkhead fitting if damaged.
C. Tighten loose connections.
14-102. Installation - Engine Flush Kit
A. Install the bulkhead fitting into the cowl ring.
B. Remove the cap from the flush nozzle and install the flush kit line. Tighten the
connections.
Rev. 5
MM-14-29
Aug 4/06
14-103. Nose Positioned Camera Mount
14-104. Description - Nose Positioned Camera Mount
NOTE
Installation of the Nose Positioned Camera Mount Kit does not authorize
installation of a camera system. Installation of specific equipment on the
mount may require additional authorization from an appropriate certification
authority.
An optional nose positioned camera mount is available for 480/B. It provides provisions
for mounting a ball/turret type camera under the nose of the aircraft and for mounting a monitor
off of the right side of the instrument panel.
The nose mounted camera mount installation consists of an aluminum sheet metal box
structure and an external steel sheet metal mount. The aft end of the box structure is attached
to the vertical panels that support the instrument panel. The lower portion of the box structure is
attached to the cabin between the chin windows. The external steel mount is located on the
outside of the cabin at the forward end of the box structure. It is fastened to the box structure
through the fiberglass cabin.
The camera mount has been certified, both structurally and in flight test, with equipment
weighing 100 lbs/45.5 kg. The frontal area of the equipment was 1.756 ft2/.163 m2 with a center
of gravity (CG) located 12.0 inches/30.5 cm below the center line of the external mount. Refer
to Figure 14-1 for the external mount foot print.
The monitor mount consists of an aluminum angle with gusset supports which is attached
to the honeycomb panel on the right side of the instrument panel and was structurally certified
with equipment weighing 4.86 lbs/2.21 kg (monitor and articulating arm). The vertical moment
arm limit is 7.4 inches/18.8 cm and the horizontal moment arm limit is 10.4 inches/26.4 cm.
Refer to Figure 14-2 for the monitor mount foot print.
14-105. Removal - Nose Positioned Camera Mount
A. Remove the external mount using the following procedure:
(1) Remove the hardware securing the external mount to the aircraft and remove
the mount.
B. Remove the camera mount internal box structure using the following procedure:
(1) Remove the external mount.
(2) Remove the external mount doubler.
(3) Remove the instrument panel shroud and the center pedestal trim panels.
(4) Remove the chin windows as applicable (para. 8-47,C).
Rev. 26
MM-14-30
Feb 28/2020
B. Remove the SX-5 control box from the aircraft using the following procedure:
(1) Disconnect the control box electrical connector from the copilot’s connector box
located on the right aft side of the cabin floor and remove the control box. Install
the dust cap on the airframe mounted connector.
C. Remove the SX-5 junction box from the aircraft using the following procedures:
(1) Gain access to the extended baggage compartment.
NOTE
The extended baggage compartment is the standard location for the junction
box. The junction box may be installed in an alternate location dependent
upon other optional equipment installations.
(2) Disconnect the electrical connectors from the junction box.
(3) Remove the hardware securing the junction box and remove the junction box.
D. Remove the searchlight mount (straight mount, P/N 4220060-1 or -3) from the aircraft
using the following procedure (Refer to Figure 14-3):
(1) Remove the searchlight/gimbal assembly from the aircraft.
(2) Disconnect the searchlight mount electrical harness from the aircraft. Install the
dust cap on the airframe mounted connector.
(3) Remove the inboard bolt from the searchlight mount and the crosstube.
(4) Remove the outboard horizontal bolt from the mount and the crosstube.
(5) Lift up the crosstube step (if installed) and remove the nut and washer(s) from
the outboard vertical bolt.
(6) Remove the searchlight mount and reinstall the bolts and hardware. Adjust the
amount of washers as required to compensate for removing the searchlight
mount.
E. Remove the searchlight mount (elevated mount, P/N 4220067-1 or -9) as follows
(Refer to Figure 14-4):
(1) Remove the searchlight/gimbal assembly from the aircraft.
(2) Disconnect the searchlight mount electrical harness from the aircraft. Install the
dust cap on the airframe mounted connector.
(3) Remove the hardware attaching the searchlight mount step to the airframe step.
Rev. 17
MM-14-39
Jun 24/11
(4) Remove the inboard and outboard bolts from the searchlight mount and the
crosstube.
(5) Remove the searchlight mount and reinstall the bolts and hardware in the
crosstube. Adjust the amount of washers as required to compensate for
removing the searchlight mount.
NOTE
The aft crosstube cover (step), P/N 4174032-12, may be installed after the
searchlight mount is removed. Refer to the TH-28/480 Illustrated Parts
Catalog (IPC) for the correct hardware configuration.
14-112. Inspection - Searchlight Kit
A. Inspect the airframe searchlight mount for corrosion, nicks, scratches, dents, cracks,
and security of installation.
B. Inspect the searchlight/gimbal assembly interface mount and airframe mount interface
for damage and/or excessive wear.
C. Inspect the junction box installation for damage to the mounting structure and loose
or missing hardware.
D. Inspect the searchlight kit electrical harnesses and connectors IAW paragraph 6-13.
E. Inspect the SX-5 system components IAW with the latest revision of the SX-5
Starburst® Searchlight User’s Manual (Doc# 031718).
14-113. Repair - Searchlight Kit
A. Repair the airframe searchlight mount as follows:
(1) Replace damaged or corroded installation hardware as applicable.
(2) Corrosion, nicks, and scratches less than .020"/.51 mm deep can be polished
out and a protective coating applied. Replace the mount if damage exceeds
.020"/.51 mm deep.
(3) Replace the mount if smooth dents exceed .030"/.76 mm.
(4) Cracks may be repaired IAW the procedures in AC43.13-1B.
(5) Replace the mount if damaged beyond repair or economically unrepairable.
Rev. 26
MM-14-40
Feb 28/2020
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