Helicopter Flying Handbook (2019)

5-2

ROBINSON R22

OTORCRAFT

LIGHT

ANUAL

Figure 5-1.

The RFM is a regulatory document in terms of the

maneuvers, procedures, and operating limitations described therein.

However, if “Pilot’s Operating Handbook” is used as the main
title instead of “Rotorcraft Flight Manual,” a statement must
be included on the title page indicating that the document
is the Federal Aviation Administration (FAA) approved
Rotorcraft Flight Manual (RFM).

[Figure 5-1]

Not including the preliminary pages, an FAA-approved
RFM may contain as many as ten sections. These sections
are: General Information; Operating Limitations; Emergency
Procedures; Normal Procedures; Performance; Weight
and Balance; Aircraft and Systems Description; Handling,
Servicing, and Maintenance Supplements; and Safety
and Operational Tips. Manufacturers have the option of
including a tenth section on safety and operational tips and
an alphabetical index at the end of the handbook.

Preliminary Pages

While RFMs may appear similar for the same make and
model of aircraft, each flight manual is unique since it
contains specific information about a particular aircraft,
such as the equipment installed, and weight and balance
information. Therefore, manufacturers are required to include
the serial number and registration on the title page to identify
the aircraft to which the flight manual belongs. If a flight
manual does not indicate a specific aircraft registration and
serial number, it is limited to general study purposes only.

Most manufacturers include a table of contents, which
identifies the order of the entire manual by section number
and title. In addition, some helicopters may include a log of
changes or a revision page to track changes to the manual.
Usually, each section also contains its own table of contents.
Page numbers reflect the section being read, 1-1, 2-1, 3-1, and
so on. If the flight manual is published in looseleaf form, each
section is usually marked with a divider tab indicating the
section number or title, or both. The emergency procedures
section may have a red tab for quick identification and
reference.

General Information (Section 1)

The general information section provides the basic descriptive
information on the rotorcraft and the powerplant. In some
manuals there is a three-view drawing of the rotorcraft that
provides the dimensions of various components, including
the overall length and width, and the diameter of the rotor
systems. This is a good place for pilots to quickly familiarize
themselves with the aircraft. Pilots need to be aware of the
dimensions of the helicopter since they often must decide
the suitability of an operations area for themselves, as well
as hanger space, landing pad, and ground handling needs.

Pilots can find definitions, abbreviations, explanations of
symbology, and some of the terminology used in the manual
at the end of this section. At the option of the manufacturer,
metric and other conversion tables may also be included.

Operating Limitations (Section 2)

The operating limitations section contains only those
limitations required by regulation or that are necessary for
the safe operation of the rotorcraft, powerplant, systems,
and equipment. It includes operating limitations, instrument
markings, color coding, and basic placards. Some of the
areas included are: airspeed, altitude, rotor, and powerplant
limitations, including fuel and oil requirements; weight and
loading distribution; and flight limitations.

Instrument Markings

Instrument markings may include, but are not limited to,
green, red, and yellow ranges for the safe operation of the
aircraft. The green marking indicates a range of continuous
operation. The red range indicates the maximum or minimum
operation allowed while the yellow range indicates a caution
or transition area.

Airspeed Limitations

Airspeed limitations are shown on the airspeed indicator
by color coding and on placards or graphs in the aircraft. A
red line on the airspeed indicator shows the airspeed limit
beyond which structural damage could occur. This is called
the never exceed speed, or V

. The normal operating speed

range is depicted by a green arc. A blue or a red cross-hatched
line is sometimes added to show the maximum autorotation
speed.

[Figure 5-2]

Other airspeed limitations may be included in this section
of the RFM. Examples include reduced V

when doors are

removed, maximum airspeed for level flight with maximum
continuous power (V

), or restrictions when carrying an

external load. Pilots need to understand and adhere to all
airspeed limitations appropriate to the make, model, and
configuration of the helicopter being flown.

5-3

Airspeed-knots

0 to 130 Knots (0 to 150 MPH) continuous operation

130 Knots (150 MPH) maximum

100 Knots (115 MPH) maximum for autorotation

150

120

100

KNOTS

AIRSPEED

MPH

x 10

RPM

X100

ROTOR

ENGINE

60 70

100

110

120

TORQUE

PERCENT

TURB

OUT

TEMP

°C x 100

4 5

Figure 5-2.

Typical airspeed indicator limitations and markings.

Figure 5-3.

Markings on a typical dual-needle tachometer in a

reciprocating-engine helicopter. The outer band shows the limits
of the superimposed needles when the engine is turning the rotor.
The inner band indicates the power-off limits.

Figure 5-4.

Torque and turbine outlet temperature (TOT) gauges

are commonly used with turbine-powered aircraft.

Altitude Limitations

If the rotorcraft has a maximum operating density altitude
(see page 7-2), it is indicated in this section of the flight
manual. Sometimes the maximum altitude varies based on
different gross weights.

Rotor Limitations

Low rpm does not produce sufficient lift, and high rpm may
cause structural damage, therefore rotor rpm limitations have
minimum and maximum values. A green arc depicts the
normal operating range with red lines showing the minimum
and maximum limits.

[Figure 5-3]

There are two different rotor rpm limitations: power-on and
power-off. Power-on limitations apply anytime the engine
is turning the rotor and is depicted by a fairly narrow green
band. A yellow arc may be included to show a transition
range, which means that operation within this range is limited
due to the possibility of increased vibrations or harmonics.
This range may be associated with tailboom dynamic modes.
Power-off limitations apply anytime the engine is not turning
the rotor, such as when in an autorotation. In this case, the
green arc is wider than the power-on arc, indicating a larger
operating range.

Powerplant Limitations

The powerplant limitations area describes operating
limitations on the helicopter’s engine including such items
as rpm range, power limitations, operating temperatures,
and fuel and oil requirements. Most turbine engines and
some reciprocating engines have a maximum power and a

maximum continuous power rating. The “maximum power”

rating is the maximum power the engine can generate and
is usually limited by time. The maximum power range is
depicted by a yellow arc on the engine power instruments,
with a red line indicating the maximum power that must not

be exceeded. “Maximum continuous power” is the maximum
power the engine can generate continually and is depicted
by a green arc.

[Figure 5-4]

Manifold pressure is a measure of vacuum at the intake
manifold. It is the difference between the air pressure
(or vacuum) inside the intake manifold and the relative
atmospheric pressure of the air around the engine. The
red line on a manifold pressure gauge indicates the
maximum amount of power. A yellow arc on the gauge
warns of pressures approaching the limit of rated power.

5-4

INCHES

OF MERCURY

MANIFOLD

PRESSURE

0 109 109 105 84 61 --

20 109 109 94 72 49 --

40 109 103 81 59 -- --

60 109 91 70 48 -- -- --

80 109 80 59 -- -- -- --

100 109 70 48 -- -- -- --

0 109 109 109 109 98 77 58

20 109 109 109 109 85 67 48

40 109 109 109 96 75 57

60 109 109 108 84 66 48

80 109 109 95 74 57 --

100 109 108 84 66 48 --

—MPH IAS

Gross

Weight

Press Alt.

(1,000 ft.)

2 4 6 8 10 12 14

Maximum V

Doors off—102 MPH IAS

than

1,700 lb

or less

F OAT

110

100

MAX ALT.

-20°C

0°C

+20°C

+40°C

NEVER EXCEED SPEED

Pressure Altitude (1,000 feet)

KIAS

Figure 5-5.

The manifold pressure gauge is an engine instrument

typically used in piston aircraft engines to measure the pressure
inside the induction system of an engine. Manifold pressure is a
measurement of vacuum and the measurement is taken at the intake
manifold.

Figure 5-6.

Various VNE placards.

[Figure 5-5]

A placard near the gauge lists the maximum

readings for specific conditions.

Weight and Loading Distribution

The weight and loading distribution section of the
manufacturer's RFM contains the maximum certificated
weights, as well as the center of gravity (CG) range. The
location of the reference datum used in balance computations
should also be included in this section. Weight and balance
computations are not provided here, but rather in the weight
and balance section of the RFM.

Flight Limitations

This area lists any maneuvers which are prohibited, such
as acrobatic flight or flight into known icing conditions. If
the rotorcraft can only be flown in visual flight rules (VFR)
conditions, it is noted in this area. Also included are the
minimum crew requirements, and the pilot seat location, if
applicable, from which solo flights must be conducted.

Placards

All rotorcraft generally have one or more placards displayed
that have a direct and important bearing on the safe operation
of the rotorcraft. These placards are located in a conspicuous
place within the cabin and normally appear in the limitations
section. Since V

varies with altitude, this placard can be

found in all helicopters.

[Figure 5-6]

Emergency Procedures (Section 3)

Concise checklists describing the recommended procedures
and airspeeds for coping with various types of emergencies
or critical situations can be found in this section. Some of

the emergencies covered include: engine failure in a hover
and at altitude, tail rotor failures, fires, and systems failures.
The procedures for restarting an engine and for ditching in
the water might also be included.

Manufacturers may first show the emergencies checklists in
an abbreviated form with the order of items reflecting the
sequence of action. This is followed by amplified checklists
providing additional information to clarify the procedure. To
be prepared for an abnormal or emergency situation, learn
the first steps of each checklist, if not all the steps. If time
permits, refer to the checklist to make sure all items have
been covered. For more information on emergencies, refer
to Chapter 11, Helicopter Emergencies and Hazards.

Manufacturers are encouraged to include an optional area
titled Abnormal Procedures, which describes recommended
procedures for handling malfunctions that are not considered
to be emergencies. This information would most likely be
found in larger helicopters.

5-5

Gross Weight (lb)

Pressure Altitude (ft)

1,500

1,400

1,600

1,700

1,800

2,000

4,000

6,000

8,000

10,000

12,000

Outside air temperature 120°F

Outside air temperature 100°F

Outside air temperature 80°F

Outside air temperature 60°F

Outside air temperature 40°F

Outside air temperature 20°F

Outside air temperature 0°F

8,000 FT DENSITY ALTITUDE

MIXTURE FULL RICH

Figure 5-7.

One of the performance charts in the performance

section is the In Ground Effect Hover Ceiling versus Gross Weight
chart. This chart can be used to determine how much weight can
be carried and still operate at a specific pressure altitude or, if
carrying a specific weight, detrmine that specific altitude limitation.

Normal Procedures (Section 4)

The normal procedures section is the section most frequently
used. It usually begins with a listing of airspeeds that
may enhance the safety of normal operations. It is a good
idea to learn the airspeeds that are used for normal flight
operations. The next part of the section includes several
checklists, which cover the preflight inspection, before-
starting procedure, how to start the engine, rotor engagement,
ground checks, takeoff, approach, landing, and shutdown.
Some manufacturers also include the procedures for practice
autorotations. To avoid skipping an important step, always
use a checklist when one is available. More information
on maneuvers can be found in Chapter 9, Basic Flight
Maneuvers, and Chapter 10, Advanced Flight Maneuvers.

Performance (Section 5)

The performance section contains all the information required
by the regulations and any additional performance information
the manufacturer determines may enhance a pilot’s ability to
operate the helicopter safely. Although the performance section
is not in the limitation section and is therefore not a limitation,
operation outside or beyond the flight-tested and documented
performance section can be expensive, slightly hazardous, or
outright dangerous to life and property. If the helicopter is
certificated under 14 CFR part 29, then the performance section
may very well be a restrictive limitation. In any event, a pilot
should determine the performance available and plan to stay
within those parameters.

These charts, graphs, and tables vary in style, but all contain
the same basic information. Some examples of the performance
information that can be found in most flight manuals include
a calibrated versus indicated airspeed conversion graph,
hovering ceiling versus gross weight charts, and a height-
velocity diagram.

[Figure 5-7]

For information on how to use

the charts, graphs, and tables, refer to Chapter 7, Helicopter
Performance.

Weight and Balance (Section 6)

The weight and balance section should contain all the
information required by the FAA that is necessary to calculate
weight and balance. To help compute the proper data, most
manufacturers include sample problems. Weight and balance
is detailed in Chapter 6, Weight and Balance.

Aircraft and Systems Description

(Section 7)

The aircraft and systems description section is an excellent
place to study all the systems found on an aircraft. The
manufacturers should describe the systems in a manner that
is understandable to most pilots. For larger, more complex

helicopters, the manufacturer may assume a higher degree of
knowledge. For more information on helicopter systems, refer
to Chapter 4, Helicopter Components, Sections, and Systems.

Handling, Servicing, and Maintenance

(Section 8)

The handling, servicing, and maintenance section describes
the maintenance and inspections recommended by the
manufacturer, as well as those required by the regulations,
and airworthiness directive (AD) compliance procedures.
There are also suggestions on how the pilot/operator can
ensure that the work is done properly.

This section also describes preventative maintenance that
may be accomplished by certificated pilots, as well as the
manufacturer’s recommended ground handling procedures,
including considerations for hangaring, tie down, and general
storage procedures for the helicopter.

6-2

Weight

When determining if a helicopter is within the weight limits,
consider the weight of the basic helicopter, crew, passengers,
cargo, and fuel. Although the effective weight (load factor)
varies during maneuvering flight, this chapter primarily
addresses the weight of the loaded helicopter while at rest.

It is critical to understand that the maximum allowable weight
may change during the flight. When operations include out of
ground effect (OGE) hovers and confined areas, planning must
be done to ensure that the helicopter is capable of lifting the
weight during all phases of flight. The weight may be acceptable
during the early morning hours, but as the density altitude
increases during the day, the maximum allowable weight may
have to be reduced to keep the helicopter within its capability.

The following terms are used when computing a helicopter’s
weight:

•   Basic Empty Weight
•   Maximum Gross Weight
•   Weight Limitations

Basic Empty Weight

The starting point for weight computations is the basic empty
weight. This is the weight of the standard helicopter, optional
equipment, unusable fuel, and all operating fluids including
engine and transmission oil, and hydraulic fluid for those
aircraft so equipped. Some helicopters might use the term
“licensed empty weight,” which is nearly the same as basic
empty weight, except that it does not include full engine and
transmission oil, just undrainable oil. If flying a helicopter
that lists a licensed empty weight, be sure to add the weight
of the oil to the computations.

Maximum Gross Weight

The maximum weight of the helicopter is referred to its
maximum gross weight. Most helicopters have an internal
maximum gross weight, which refers to the weight within the
helicopter structure and an external maximum gross weight,
which refers to the weight of the helicopter with an external
load. The external maximum weight may vary depending
on where it is attached to the helicopter. Some large cargo
helicopters may have several attachment points for sling load
or winch operations. These helicopters can carry a tremendous
amount of weight when the attachment point is directly under
the CG of the aircraft.

Weight Limitations

Weight limits are necessary to guarantee the structural
integrity of the helicopter, enable pilots to predict helicopter
performance and insure aircraft controllability. Although
aircraft manufacturers build in safety factors, a pilot should

never intentionally exceed the load limits for which a
helicopter is certificated.

Operating below a minimum weight could adversely affect
the handling characteristics of the helicopter. During single-
pilot operations in some helicopters, a pilot needs to use a
large amount of forward cyclic to maintain a hover. By adding
ballast to the helicopter, the neutral cyclic position can be
shifted toward the center of its range, thus giving a greater
range of control outward from neutral in every direction.
When operating at or below the minimum weight of the
helicopter, additional weight also improves autorotational
characteristics since the autorotational descent can be
established sooner. In addition, operating below minimum
weight could prevent achieving the desirable rotor revolutions
per minute (rpm) during autorotations.

Operating above a maximum weight could result in
structural deformation or failure during flight if encountering
excessive load factors, strong wind gusts, or turbulence.
Weight and maneuvering limitations also are factors in
establishing fatigue life of components. Overweight, meaning
overstressed, parts fail sooner than anticipated. Therefore,
premature failure is a major consideration in determination
of fatigue life and life cycles of parts.

Although a helicopter is certificated for a specified maximum
gross weight, it is not safe to take off with this load under
some conditions. Anything that adversely affects takeoff,
climb, hovering, and landing performance may require
off-loading of fuel, passengers, or baggage to some weight
less than the published maximum. Factors that can affect
performance include high altitude, high temperature, and high
humidity conditions, which result in a high-density altitude.
In-depth performance planning is critical when operating in
these conditions.

Balance

Helicopter performance is not only affected by gross weight,
but also by the position of that weight. It is essential to load the
aircraft within the allowable CG range specified in the rotorcraft
flight manual’s (RFM) weight and balance limitations. Loading
outside approved limits can result in insufficient control travel
for safe operation.

Center of Gravity

The pilot should ensure that the helicopter is properly balanced
and within its center of gravity limitations, so that minimal
cyclic input is required during hovering flight, except for
any wind corrections. Since the fuselage acts as a pendulum
suspended from the rotor, changing the CG changes the angle
at which the aircraft hangs from the rotor. When the CG is
directly under the rotor mast, the helicopter hangs horizontally;
if the CG is too far forward of the mast, the helicopter hangs

6-3

CG Directly Under The Rotor Mast

Forward CG

Aft CG

Figure 6-1.

The location of the CG strongly influences how the helicopter handles.

with its nose tilted down; if the CG is too far aft of the mast,
the nose tilts up.

[Figure 6-1]

CG Forward of Forward Limit

A forward CG may occur when a heavy pilot and passenger
take off without baggage or proper ballast located aft of the
rotor mast. This situation becomes worse if the fuel tanks
are located aft of the rotor mast because as fuel burns the
CG continues to shift forward.

This condition is easily recognized when coming to a hover
following a vertical takeoff. The helicopter has a nose-low
attitude, and excessive rearward displacement of the cyclic
control is needed to maintain a hover in a no-wind condition.
Do not continue flight in this condition, since a pilot could
rapidly lose rearward cyclic control as fuel is consumed. A
pilot may also find it impossible to decelerate sufficiently to
bring the helicopter to a stop. In the event of engine failure
and the resulting autorotation, there may not be enough cyclic
control to flare properly for the landing.

A forward CG is not as obvious when hovering into a strong
wind, since less rearward cyclic displacement is required than
when hovering with no wind. When determining whether a
critical balance condition exists, it is essential to consider the
wind velocity and its relation to the rearward displacement
of the cyclic control.

CG Aft of Aft Limit

Without proper ballast in the cockpit, exceeding the aft CG
may occur when:

•

A lightweight pilot takes off solo with a full load of
fuel located aft of the rotor mast.

•

A lightweight pilot takes off with maximum baggage
allowed in a baggage compartment located aft of the
rotor mast.

• A lightweight pilot takes off with a combination of

baggage and substantial fuel where both are aft of the
rotor mast.

A pilot can recognize the aft CG condition when coming
to a hover following a vertical takeoff. The helicopter will
have a tail-low attitude and will need excessive forward
displacement of cyclic control to maintain a hover in a no-
wind condition. When facing upwind, even greater forward
cyclic is needed.

If flight is continued in this condition, it may be impossible
to fly in the upper allowable airspeed range due to inadequate
forward cyclic authority to maintain a nose-low attitude. In
addition, with an extreme aft CG, gusty or rough air could
accelerate the helicopter to a speed faster than that produced
with full forward cyclic control. In this case, dissymmetry of
lift and blade flapping could cause the rotor disk to tilt aft.
With full forward cyclic control already applied, a pilot might
not be able to lower the rotor disk, resulting in possible loss
of control, or the rotor blades striking the tailboom.

Lateral Balance

For smaller helicopters, it is generally unnecessary to
determine the lateral CG for normal flight instruction and
passenger flights. This is because helicopter cabins are
relatively narrow and most optional equipment is located
near the centerline. However, some helicopter manuals
specify the seat from which a pilot must conduct solo flight.
In addition, if there is an unusual situation that could affect
the lateral CG, such as a heavy pilot and a full load of fuel
on one side of the helicopter, its position should be checked
against the CG envelope. If carrying external loads in a
position that requires large lateral cyclic control displacement
to maintain level flight, fore and aft cyclic effectiveness could
be limited dramatically. Manufacturers generally account
for known lateral CG displacements by locating external
attachment points opposite the lateral imbalance. Examples
are placement of hoist systems attached to the side, and wing
stores commonly used on military aircraft for external fuel
pods or armament systems.

6-4

Horizontal

datum

−

Aviation Gasoline (AVGAS). . . . . . . . . . . . . . . . . . . . .  6 lb/gal
Jet Fuel (JP-4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6.5 lb/gal
Jet Fuel (JP-5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6.8 lb/gal
Reciprocating Engine Oil. . . . . . . . . . . . . . . . . . . . .  7.5 lb/gal*
Turbine Engine Oil. . . . . . . . . .  Varies between 6 and 8 lb/gal*
Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8.35 lb/gal

Oil weight is given in pounds per gallon while oil capacity is

usually given in quarts; therefore, convert the amount of oil to

gallons before calculating its weight. Remember, four quarts

equal one gallon.

Figure 6-2.

When making weight and balance computations, always

use actual weights if they are available, especially if the helicopter
is loaded near the weight and balance limits.

Figure 6-3.

While the horizontal reference datum can be anywhere

the manufacturer chooses, some manufacturers choose the datum
line at or ahead of the most forward structural point on the
helicopter, in which case all moments are positive. This aids in
simplifying calculations. Other manufacturers choose the datum
line at some point in the middle of the helicopter, in which case
moments produced by weight in front of the datum are negative and
moments produced by weight aft of the datum are positive.

Weight and Balance Calculations

When determining whether a helicopter is properly loaded,
two questions must be answered:

1. Is the gross weight less than or equal to the maximum

allowable gross weight?

2. Is the CG within the allowable CG range, and will

it stay within the allowable range throughout the
duration of flight including all loading configurations
that may be encountered?

To answer the first question, just add the weight of the items
comprising the useful load (pilot, passengers, fuel, oil [if
applicable] cargo, and baggage) to the basic empty weight of
the helicopter. Ensure that the total weight does not exceed
the maximum allowable gross weight.

To answer the second question, use CG or moment
information from loading charts, tables, or graphs in the
RFM. It is important to note that any weight and balance
computation is only as accurate as the information provided.
Therefore, ask passengers what they weigh and add a few
pounds to account for the additional weight of clothing,
especially during the winter months. Baggage should be
weighed on a scale, if practical. If a scale is not available,
compute personal loading values according to each individual
estimate.

Figure 6-2

indicates the standard weights for

specific operating fluids. These values are used when
computing a helicopter’s balance.

Reference Datum

Balance is determined by the location of the CG, which
is usually described as a given number of inches from the
reference datum. The horizontal reference datum is an
imaginary vertical plane or point, arbitrarily fixed somewhere
along the longitudinal axis of the helicopter, from which all
horizontal distances are measured for weight and balance

purposes. There is no fixed rule for its location. It may be
located at the rotor mast, the nose of the helicopter, or even
at a point in space ahead of the helicopter.

[Figure 6-3]

The lateral reference datum is usually located at the center
of the helicopter. The location of the reference datum is
established by the manufacturer and is defined in the RFM.

[Figure 6-4]

Chapter Summary

This chapter discusses the importance of computing the
weight and balance of the helicopter. The chapter also
discusses the common terms and meanings associate with
weight and balance.

7-2

Factors Affecting Performance

A helicopter’s performance is dependent on the power output
of the engine and the lift produced by the rotors, whether
it is the main rotor(s) or tail rotor. Any factor that affects
engine and rotor efficiency affects performance. The three
major factors that affect per formance are density altitude,
weight, and wind. The Pilot’s Handbook of Aeronautical
Knowledge, FAA-H-8083-25 (as revised), discusses these
factors in great detail.

Moisture (Humidity)

Humidity alone is usually not considered an important factor
in calculating density altitude and helicopter performance;
however, it does contribute. There are no rules of thumb used
to compute the effects of humidity on density altitude, but
some manufacturers include charts with 80 percent relative
humidity columns as additional information. There appears
to be an approximately 3–4 percent reduction in performance
compared to dry air at the same altitude and temperature,
so expect a decrease in hovering and takeoff performance
in high humidity conditions. Although 3–4 percent seems
insignificant, it can be the cause of a mishap when already
operating at the limits of the helicopter.

Weight

Weight is one of the most important factors because the pilot
can control it. Most performance charts include weight as one
of the variables. By reducing the weight of the helicopter, a
pilot may be able to take off or land safely at a location that
otherwise would be impossible. However, if ever in doubt
about whether a takeoff or landing can be performed safely,
delay your takeoff until more favorable density altitude
conditions exist. If airborne, try to land at a location that has
more favorable conditions, or one where a landing can be
made that does not require a hover.

In addition, at higher gross weights, the increased power
required to hover produces more torque, which means more
antitorque thrust is required. In some heli copters during high
altitude operations, the maximum antitorque produced by the
tail rotor during a hover may not be sufficient to overcome
torque even if the gross weight is within limits.

Winds

Wind direction and velocity also affect hovering, take off, and
climb performance. Translational lift occurs any time there
is relative airflow over the rotor disk. This occurs whether
the relative airflow is caused by helicopter movement or by
the wind. Assuming a headwind, as wind speed increases,
translational lift increases, resulting in less power required
to hover.

The wind direction is also an important consideration.
Headwinds are the most desirable as they contribute to the
greatest increase in performance. Strong crosswinds and
tailwinds may require the use of more tail rotor thrust to
maintain directional control. This increased tail rotor thrust
absorbs power from the engine, which means there is less
power available to the main rotor for the production of
lift. Some helicopters even have a critical wind azimuth or
maximum safe relative wind chart. Operating the helicopter
beyond these limits could cause loss of tail rotor effectiveness.

Takeoff and climb performance is greatly affected by wind.
When taking off into a headwind, effective trans lational lift
is achieved earlier, resulting in more lift and a steeper climb
angle. When taking off with a tailwind, more distance is
required to accelerate through transla tion lift.

Performance Charts

In developing performance charts, aircraft manufacturers
make certain assumptions about the condition of the
helicopter and the ability of the pilot. It is assumed that
the helicopter is in good operating condition, calm wind,
and the engine is developing its rated power. The pilot is
assumed to be following normal operating procedures and
to have average flying abilities. Average means a pilot
capable of doing each of the required tasks cor rectly and at
the appropriate times.

Using these assumptions, the manufacturer devel ops
performance data for the helicopter based on actual flight
tests. However, they do not test the hel icopter under each
and every condition shown on a performance chart. Instead,
they evaluate specific data and mathematically derive the
remaining data.

Height/Velocity Diagram

The height/velocity (H/V) diagram shows the combinations
of airspeed and height above the ground, which will allow
an average pilot to successfully complete a landing after
an engine failure. By carefully studying the height/velocity
diagram, a pilot is able to avoid the combinations of altitude
and airspeed that may not allow sufficient time or altitude to
enter a stabilized autorotative descent. Refer to

Figure 7-1

during the remainder of the discussion on the height/velocity
diagram.

In the simplest explanation, the H/V diagram is a diagram in
which the shaded areas should be avoided, as the pilot may be
unable to complete an autorotation landing without damage.
The H/V diagram usually contains a takeoff profile, where the
diagram can be traversed from zero height and zero speed to

7-3

Feet AGL

KIAS

Height/Velocity Diagram

700

650

600

550

500

450

400

350

300

250

200

150

100

0 10 20 30 40 50 60 70 80 90 100

110 120 130

Avoid operation in shaded areas

8500 FT Density Altitude at 2500 LB

Sea Level at 2500 LB

Recommended

Takeoff Profile

Figure 7-1.

Sample height/velocity diagram for a Robinson Model

R44 II.

cruise, without entering the shaded areas or with minimum
exposure to shaded areas.

The grey portion on the left side of the diagram marks a flight
profile that probably does not allow the pilot to complete an
autorotation successfully, primarily due to having insufficient
airspeed to enter an autorotative profile in time to avoid
a crash. The shaded area on the lower right is dangerous
due to the airspeed and proximity to the ground resulting
in dramatically reduced reaction time for the pilot in the
case of mechanical failure, or other in-flight emergencies.
This shaded area at the lower right is not portrayed in H/V
diagrams for multiengine helicopters capable of safely
hovering and flying with a single engine failure.

The following examples further illustrate the relevance of
the H/V diagram to a single-engine helicopter.

At low heights with low airspeed, such as a hover taxi, the
pilot can simply use the kinetic energy from the rotor disk
to cushion the landing with collective, converting rotational
inertia to lift. The aircraft is in a safe part of the H/V diagram.
At the extreme end of the scale (e.g., a three-foot hover
taxi at walking pace) even a complete failure to recognize
the power loss resulting in an uncushioned landing would
probably be survivable.

As the airspeed increases without an increase in height, there
comes a point at which the pilot’s reaction time would be
insufficient to react with a flare in time to prevent a high
speed, and thus probably fatal, ground impact. Another thing
to consider is the length of the tailboom and the response
time of the helicopter flight controls at slow airspeeds and
low altitudes. Even small increases in height give the pilot
much greater time to react; therefore, the bottom right part of
the H/V diagram is usually a shallow gradient. If airspeed is
above ideal autorotation speed, the pilot’s instinct is usually
to flare to convert speed to height and increase rotor rpm
through coning, which also immediately gets them out of the
dead man’s curve.

Conversely, an increase in height without a corresponding
increase in airspeed puts the aircraft above a survivable
uncushioned impact height, and eventually above a height
where rotor inertia can be converted to sufficient lift to enable
a survivable landing. This occurs abruptly with airspeeds
much below the ideal autorotative speed (typically 40–80
knots). The pilot must have enough time to accelerate to
autorotation speed in order to autorotate successfully; this
directly relates to a requirement for height. Above a certain
height the pilot can achieve autorotation speed even from a
zero knot start, thus putting high OGE hovers outside the
curve.

The typical safe takeoff profile involves initiation of forward
flight from a 2–3 feet landing gear height, only gaining
altitude as the helicopter accelerates through translational
lift, as airspeed approaches a safe autorotative speed. At this
point, some of the increased thrust available may be used to
attain safe climb airspeed, which will keep the helicopter out
of the shaded or hatched areas of the H/V diagram. Although
helicopters are not restricted from conducting maneuvers
that will place them in the shaded area of the H/V diagram,
it is important for pilots to understand that operation in
those shaded areas exposes pilot, aircraft, and passengers to
a certain hazard should the engine or driveline malfunction.
The pilot should always evaluate the risk of the maneuver
versus the operational value.

The Effect of Weight Versus Density Altitude

The height/velocity diagram

[Figure 7-1]

depicts altitude and

airspeed situations from which a successful autorotation can
be made. The time required, and therefore, altitude necessary
to attain a steady state autorotative descent, is dependent on
the weight of the helicopter and the density altitude. For this
reason, the H/V diagram is valid only when the helicopter is
operated in accordance with the gross weight versus density
altitude chart. If published, this chart is found in the RFM
for the particular helicopter.

[Figure 7-2]

The gross weight

7-4

Density altitude (thousands of feet)

Gross weight (pounds)

2,300 2,400 2,500 2,600 2,700 2,800

Figure 7-2.

Gross weight versus density altitude.

versus density altitude chart is not intended to provide a
restriction to gross weight, but to be an advisory of the
autorotative capability of the helicopter during takeoff and
climb. A pilot must realize, however, that at gross weights
above those recommended by the gross weight versus density
altitude chart, the values are unknown.

Assuming a density altitude of 8,500 feet, the height/velocity
diagram in

Figure 7-1

would be valid up to a gross weight of

approximately 2,500 pounds. This is found by entering the
graph in

Figure 7-2

at a density altitude of 8,500 feet (point A),

then moving horizontally to the solid line (point B). Moving
vertically to the bottom of the graph (point C), with the existing
density altitude, the maximum gross weight under which the
height/velocity diagram is applicable is 2,500 pounds.

The production of performance charts and diagrams for
helicopters are regulatory as set out in Title 14 of the Code
of Federal Regulations (14 CFR) Part 27, Airworthiness
Standards. These charts establish safer parameters for
operation. Although not regulatory, the pilot should carry
out a full risk assessment to carefully consider the higher
risk before operating within the shaded areas of the height/
velocity diagram.

Autorotational Performance

Most autorotational performance charts state that autorotational
descent performance is a function of indicated airspeed (IAS)
and is essentially unaffected by density altitude and gross
weight. Keep in mind that, at some point, the potential energy

expended during the autorotation is converted into kinetic
energy for the flare and touchdown phase of the maneuver. It is
at that point that increased density altitudes and heavier gross
weights have a great impact on the successful completion of
the autorotation. The rotor disk must be able to overcome the
downward momentum of the helicopter and provide enough
lift to cushion the landing. With increased density altitudes
and gross weights, the lift potential is reduced and a higher
collective pitch angle (angle of incidence) is required.

During autorotation gravity provides the source of energy
powering the rotor by causing upflow up through the rotor
during descent. This is the same as saying that potential
energy is being traded for kinetic energy to turn the rotor as
the aircraft descends.

Figure 7-3

, the S-300 curve shows the various combinations

of horizontal and vertical speeds that supply the required
energy to keep the rotor turning at a constant 471 rpm.
For example, an airspeed of 54 mph with a corresponding
vertical speed of 1,600 feet per minute (fpm) will provide
enough kinetic energy to maintain the rotor at a 471 rpm. The
rotor does not care if the air is coming from the front or the
bottom so long as the total is sufficient to maintain the rpm.
Any point on the curve will maintain rotor speed. However,
the pilot does care because if he or she, for example, glides
at 30 knots, the corresponding rate of descent will be over
2,200 fpm. Since there is little airspeed for a deceleration
(or “flare”) to reduce the rate of decent before touchdown,
the collective pitch application (increasing blade pitch and
giving a final temporary increase in lift before the blades
slow down) may be insufficient to arrest the rate of descent.

Students who fully comprehend this relationship understand
why training autorotations are usually limited to airspeeds
between the minimum rate of descent airspeed and the
maximum range airspeed (usually about 25 percent faster
than the minimum rate of descent airspeed).

Referencing a curve similar to the one shown in

Figure 7-3

useful to understand the consequences of not maintaining the
target airspeed when executing an autorotation. Simply put,
the pilot should know why airspeed is the most significant
factor affecting the rate of descent.

Hovering Performance

Helicopter performance revolves around whether or not the
helicopter can be hovered. More power is required during the
hover than in any other flight regime. Obstructions aside, if
a hover can be maintained, a takeoff can be made, especially
with the additional benefit of translational lift. Hover charts
are provided for in ground effect (IGE) hover and out of
ground effect (OGE) hover under various conditions of

7-5

True airspeed - mph

Autorotation, 471 Rotor rpm

2,400

2,200

2,000

1,800

1,600

1,400

20 30 40 50 60 70 80

Rate of descent - ft/min

Figure 7-3.

An autorotation curve for the S-300 shows the various combinations of horizontal and vertical speeds that supply the required

energy to keep the rotor turning at a constant 471 rpm.

gross weight, altitude, temperature, and power. The IGE
hover ceiling is usually higher than the OGE hover ceiling
because of the added lift benefit produced by ground effect.
See Chapter 2, Aerodynamics of Flight, for more details on
IGE and OGE hover. A pilot should always plan an OGE
hover when landing in an area that is uncertain or unverified.
As density altitude increases, more power is required to
hover. At some point, the power required is equal to the
power available. This establishes the hovering ceiling under
the existing conditions. Any adjustment to the gross weight
by varying fuel, payload, or both, affects the hovering ceiling.
The heavier the gross weight, the lower the hovering ceiling.
As gross weight is decreased, the hover ceiling increases.

Sample Hover Problem 1

You are to fly a photographer to a remote location to take
pictures of the local wildlife. Using

Figure 7-4

, can you

safely hover in ground effect at your departure point with
the following conditions?

A.   Pressure Altitude................................8,000 feet
B.   Temperature..........................................+15  °C
C.   Takeoff Gross Weight.........................1,250 lb

rpm..............................................104 percent

First enter the chart at 8,000 feet pressure altitude (point A),
then move right until reaching a point mid way between the
+10 °C and +20 °C lines (point B). From that point, proceed
down to find the maximum gross weight where a 2 foot
hover can be achieved. In this case, it is approximately 1,280
pounds (point C).

Since the gross weight of your helicopter is less than this,
you can safely hover with these conditions.

Sample Hover Problem 2

Once you reach the remote location in the previous problem,
you will need to hover OGE for some of the pictures. The
pressure altitude at the remote site is 9,000 feet, and you will
use 50 pounds of fuel getting there. (The new gross weight is
now 1,200 pounds.) The temperature will remain at +15 °C.

Using

Figure 7-5

, can you accomplish the mission?

Enter the chart at 9,000 feet (point A) and proceed to point
B (+15 °C). From there, determine that the maxi mum gross

7-6

Max continuous or full throttle

OGE hover ceiling vs. gross weight

Pressure altitude (PA x feet in thousands)

900 1,000 1,100 1,200 1,300 1,400

425 450 475 500 525 550 575 600 625

Density altitude 12,600 feet

°C °F

−20

−10

+10

+20

+30

+40

−4

+14

+32

+50

+68

+86

+104

OAT

GROSS WEIGHT (LB)

OUT OF GROUND EFFECT

Full throttle (or limit manifold pressure) and 104% rpm

GROSS WEIGHT (KG)

−20°C

−10°C

0°C

+10°C

+20°C

+30°C

+40°C

Standard day

Figure 7-5.

Out of ground effect hover ceiling versus gross weight

chart.

IGE hover ceiling vs. gross weight

Pressure altitude (PA x feet in thousands)

Density altitude 12,600 feet

900 1,000 1,100 1,200 1,300 1,400

425 450 475 500 525 550 575 600 625

°C °F

−20

−10

+10

+20

+30

+40

−4

+14

+32

+50

+68

+86

+104

OAT

GROSS WEIGHT (LB)

IN GROUND EFFECT AT 2-FOOT SKID CLEARANCE

Full throttle and 104% rpm

GROSS WEIGHT (KG)

−20°C

1,370

−10°C

0°C

+10°C

+20°C

+30°C

+40°C

Standard day

Figure 7-4.

In ground effect hovering ceiling versus gross weight

chart.

weight to hover OGE is approximately 1,130 pounds (point
C). Since your gross weight is higher than this value, you will
not be able to hover in these conditions. To accomplish the
mission, you will need to remove approximately 70 pounds
before you begin the flight.

These two sample problems emphasize the importance of
determining the gross weight and hover ceiling throughout
the entire flight operation. Being able to hover at the take off
location with a specific gross weight does not ensure the
same performance at the landing point. If the destination
point is at a higher density altitude because of higher
elevation, temperature, and/or relative humidity, more power
is required to hover there. You should be able to predict
whether hovering power will be available at the destination
by knowing the temperature and wind conditions, using
the performance charts in the helicopter flight manual, and
making certain power checks during hover and in flight prior
to commencing the approach and landing.

For helicopters with dual engines, performance charts provide

torque amounts for both engines.

Sample Hover Problem 3

Using

Figure 7-6

, determine what torque is required to hover.

Use the following conditions:

A.  Pressure Altitude . . . . . . . . . . . . . . . . . . . ..9,500 feet
B.  Outside Air Temperature  . . . . . . . . . . . . . . . . . . 0 °C
C.   Gross Weight. . . . . . . . . . . . . . . . . . . . . . . . . 4,250 lb
D.  Desired Skid Height . . . . . . . . . . . . . . . . . . . . . . 5 feet

First, enter the chart at 9,500 feet pressure altitude, then
move right to outside air temperature, 0 °C. From that point,
move down to 4,250 pounds gross weight and then move left
to 5-foot skid height. Drop down to read 66 percent torque
required to hover.

Climb Performance

7-7

Mast torque - percent

Det mast torque - percent

Density altitude - feet

Pressure altitude - feet

Engine torque - percent

14000

12000

10000

8000

6000

4000

2000

100

100 90 80 70 60 50 40

-5000 0 5000

10000

15000

50 (OGE)

Skid height - feet

5500

- 60

FAT °C

- 40

- 20 0

+ 20

+ 40

+ 60

5250

5000

4750

4500

4250

4000

3750

3500

3250

3000

Gross weight - pounds

66%

Figure 7-6.

Torque required for cruise or level flight.

Most of the factors affecting hover and takeoff per formance
also affect climb performance. In addition, turbulent air, pilot
techniques, and overall condition of the helicopter can cause
climb performance to vary.

A helicopter flown at the best rate-of-climb speed (V

) obtains

the greatest gain in altitude over a given period of time. This

speed is normally used during the climb after all obstacles
have been cleared and is usu ally maintained until reaching
cruise altitude. Rate of climb must not be confused with angle
of climb. Angle of climb is a function of altitude gained over
a given distance. The V

results in the highest climb rate, but

not the steepest climb angle, and may not be sufficient to clear
obstructions. The best angle of climb speed (V

) depends upon

the power available. If there is a surplus of power available,

7-8

Legend

Maximum range
Maximum rate of climb or maximum end
Continuous torque

Torque (%)

Fuel flow (pounds per hour)

110

100

140

130

120

110

100

30 40 50 60 70 80 90 100

PRESSURE ALTITUDE = 8,000 FEET

Indicated airspeed (knots)

True airspeed (knots)

OAT 15°C

160 200 240 280

340 380 420

0 10 20

∆Torque - %

Maximum torque available

Transmission limit

Maximum rate of climb

or maximum end

Maximum range

Continuous torque available

10 SO F1 AF

5500

3500

5000

4500

4000

3000

GW (LB)

Torque (%)

1,500

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

400

300

200

100

5 10 15 20 25 30 35 40

Rate of climb or descent (feet per minute)

GROSS WEIGHT - (LB)

3000

3500

4000

4500

5000

5500

Figure 7-7.

Maximum rate-of-climb chart.

Figure 7-8.

Climb/descent torque percentage chart.

the helicopter can climb vertically, so V

is zero.

Wind direction and speed have an effect on climb
performance, but it is often misunderstood. Airspeed is
the speed at which the helicopter is moving through the
atmosphere and is unaffected by wind. Atmospheric wind
affects only the groundspeed, or speed at which the helicopter
is moving over the Earth’s surface. Thus, the only climb
performance affected by atmospheric wind is the angle of
climb and not the rate of climb.

When planning for climb performance, it is first important to
plan for torque settings at level flight. Climb performance charts
show the change in torque, above or below torque, required
for level flight under the same gross weight and atmospheric
conditions to obtain a given rate of climb or descent.

Sample Cruise or Level Flight Problem

Determine torque setting for cruise or level flight using

Figure 7-7.

Use the following conditions:

Pressure Altitude............................................... 8,000 feet
Outside Air Temperature...................................... +15 °C
A. Indicated Airspeed........................................80 knots
B. Maximum Gross Weight................................5,000 lb

With this chart, first confirm that it is for a pressure altitude
of 8,000 feet with an OAT of 15°. Begin on the left side
at 80 knots indicated airspeed (point A) and move right to
maximum gross weight of 5,000 lb (point B). From that point,
proceed down to the torque reading for level flight, which
is 74 percent torque (point C). This torque setting is used
in the next problem to add or subtract cruise/descent torque
percentage from cruise flight.

Sample Climb Problem

Determine climb/descent torque percentage using

Figure 7-8

Use the following conditions:

A. Rate of Climb or Descent . . . . . . . . . . . . . . 500 fpm
B. Maximum Gross Weight . . . . . . . . . . . . . . . 5,000 lb

With this chart, first locate a 500-fpm rate of climb or descent
(point A), and then move to the right to a maximum gross

8-2

Figure 8-1.

The pilot in command is responsible for the airworthy

condition of the aircraft and using checklists to ensure proper
inspection of the helicopter prior to flight.

Preflight

Before any flight, ensure the helicopter is airworthy by
inspecting it according to the rotorcraft flight manual (RFM),
pilot’s operating handbook (POH), or other information
supplied either by the operator or the manufacturer.
Remember that it is the responsibility of the pilot in command
(PIC) to ensure the aircraft is in an airworthy condition.

In preparation for flight, the use of a checklist is important
so that no item is overlooked.

[Figure 8-1]

Follow the

manufacturer’s suggested outline for both the inside and
outside inspection. This ensures that all the items the
manufacturer feels are important are checked. If supplemental
equipment has been added to the helicopter, these procedures
should be included on the checklist as well.

Minimum Equipment Lists (MELs) and Operations

with Inoperative Equipment

Title 14 of the Code of Federal Regulations (14 CFR) requires
that all aircraft instruments and installed equipment be
operative prior to each departure. However, when the Federal
Aviation Administration (FAA) adopted the minimum
equipment list (MEL) concept for 14 CFR part 91 operations,
flights were allowed with inoperative items, as long as the
inoperative items were determined to be nonessential for safe
flight. At the same time, it allowed part 91 operators, without
an MEL, to defer repairs on nonessential equipment within
the guidelines of part 91.

There are two primary methods of deferring maintenance
on rotorcraft operating under part 91. They are the deferral
provision of 14 CFR part 91, section 91.213(d) and an FAA-
approved MEL.

The deferral provision of 14 CFR section 91.213(d) is
widely used by most pilot/operators. Its popularity is due
to simplicity and minimal paperwork. When inoperative
equipment is found during preflight or prior to departure, the
decision should be to cancel the flight, obtain maintenance
prior to flight, determine if the flight can be made under the
limitations imposed by the defective equipment, or to defer
the item or equipment.

Maintenance deferrals are not used for in-flight discrepancies.
The manufacturer’s RFM/POH procedures are to be used in
those situations. The discussion that follows is an example of
a pilot who wishes to defer maintenance that would ordinarily
be required prior to flight.

If able to use the deferral provision of 14 CFR section
91.213(d), the pilot determines whether the inoperative
equipment is required by type design or 14 CFR. If the
inoperative item is not required, and the helicopter can be
safely operated without it, the deferral may be made. The
inoperative item shall be deactivated or removed and an
INOPERATIVE placard placed near the appropriate switch,
control, or indicator. If deactivation or removal involves
maintenance (removal always does), it must be accomplished
by certificated maintenance personnel.

For example, if the position lights (installed equipment) were
discovered to be inoperative prior to a daytime flight, the pilot
would follow the requirements of 14 CFR section 91.213(d).
The pilot must then decide if the flight can be accomplished
prior to night, when the lights will be needed.

The deactivation may be a process as simple as the pilot
positioning a circuit breaker to the

off

position, or as complex

as rendering instruments or equipment totally inoperable.
Complex maintenance tasks require a certificated and
appropriately rated maintenance person to perform the
deactivation. In all cases, the item or equipment must be
placarded INOPERATIVE.

When an operator requests an MEL, and a Letter of
Authorization (LOA) is issued by the FAA, then the use
of the MEL becomes mandatory for that helicopter. All
maintenance deferrals must be accomplished in accordance
with the terms and conditions of the MEL and the operator-
generated procedures document.

8-3

Figure 8-2.

Exercise extreme caution when hovering near buildings

or other aircraft.

The use of an MEL for rotorcraft operated under part 91 also
allows for the deferral of inoperative items or equipment. The
primary guidance becomes the FAA-approved MEL issued
to that specific operator and N-numbered helicopter.

The FAA has developed master minimum equipment lists
(MMELs) for rotorcraft in current use. Upon written request
by a rotorcraft operator, the local FAA Flight Standards
District Office (FSDO) may issue the appropriate make and
model MMEL, along with an LOA, and the preamble. The
operator then develops operations and maintenance (O&M)
procedures from the MMEL. This MMEL with O&M
procedures now becomes the operator’s MEL. The MEL,
LOA, preamble, and procedures document developed by the
operator must be on board the helicopter when it is operated.

The FAA considers an approved MEL to be a supplemental
type certificate (STC) issued to an aircraft by serial number
and registration number. It therefore becomes the authority
to operate that aircraft in a condition other than originally
type certificated.

With an approved MEL, if the position lights were discovered
inoperative prior to a daytime flight, the pilot would make
an entry in the maintenance record or discrepancy record
provided for that purpose. The item is then either repaired or
deferred in accordance with the MEL. Upon confirming that
daytime flight with inoperative position lights is acceptable in
accordance with the provisions of the MEL, the pilot would
leave the position lights switch

off

, open the circuit breaker

(or whatever action is called for in the procedures document),
and placard the position light switch as INOPERATIVE.

There are exceptions to the use of the MEL for deferral. For
example, should a component fail that is not listed in the
MEL as deferrable (the rotor tachometer, engine tachometer,
or cyclic trim, for example), then repairs are required to be
performed prior to departure. If maintenance or parts are not
readily available at that location, a special flight permit can
be obtained from the nearest FSDO. This permit allows the
helicopter to be flown to another location for maintenance.
This allows an aircraft that may not currently meet applicable
airworthiness requirements, but is capable of safe flight, to
be operated under the restrictive special terms and conditions
attached to the special flight permit.

Deferral of maintenance is not to be taken lightly, and due
consideration should be given to the effect an inoperative
component may have on the operation of a helicopter,
particularly if other items are inoperative. Further information
regarding MELs and operations with inoperative equipment
can be found in AC 9 1-67, Minimum Equipment Requirements
for General Aviation Operations Under FAR Part 91.

Engine Start and Rotor Engagement

During the engine start, rotor engagement, and systems
ground check, use the manufacturer’s checklists. If a problem
arises, have it checked before continuing. Prior to performing
these tasks, however, make sure the area around and above
the helicopter is clear of personnel and equipment. Position
the rotor blades so that they are not aligned with the fuselage.
This may prevent the engine from being started with the
blades still fastened. For a two-bladed rotor system, position
the blades so that they are perpendicular to the fuselage
and easily seen from the cockpit. Helicopters are safe and
efficient flying machines as long as they are operated within
the parameters established by the manufacturer.

Rotor Safety Considerations

The exposed nature of the main and tail rotors deserves
special caution. Exercise extreme care when taxiing near
hangars or obstructions since the distance between the
rotor blade tips and obstructions is very difficult to judge.

[Figure 8-2]

In addition, the tail rotor of some helicopters

cannot be seen from the cabin. Therefore, when hovering
backward or turning in those helicopters, allow plenty of
room for tail rotor clearance. It is a good practice to glance
over your shoulder to maintain this clearance

Another rotor safety consideration is the thrust a helicopter
generates. The main rotor system is capable of blowing sand,
dust, snow, ice, and water at high velocities for a significant
distance causing injury to nearby people and damage to
buildings, automobiles, and other aircraft. Loose snow, sand,
or soil can severely reduce visibility and obscure outside visual
references. There is also the possibility of sand and snow
being ingested into the engine intake, which can overwhelm
filters and cutoff air to the engine or allow unfiltered air into
the engine, leading to premature failure. Any airborne debris
near the helicopter can be ingested into the engine air intake
or struck by the main and tail rotor blades.

8-4

Aircraft Servicing

The helicopter rotor blades are usually stopped, and both the
aircraft and the refueling unit properly grounded prior to any
refueling operation. The pilot should ensure that the proper
grade of fuel and the proper additives, when required, are
being dispensed.

Refueling of a turbine aircraft while the blades are turning,
known as “hot refueling,” may be practical for certain types
of operation. However, this can be hazardous if not properly
conducted. Pilots should remain at the flight controls; and
refueling personnel should be knowledgeable about the
proper refueling procedures and properly briefed for specific
helicopter makes and models.

The pilot may need to train the refueling personnel on
proper hot refueling procedures for that specific helicopter.
The pilot should explain communication signs or calls,
normal servicing procedures, and emergency procedures as
a minimum. At all times during the refueling process, the
pilot should remain vigilant and ready to immediately shut
down the engine(s) and egress the aircraft. Several accidents
have occurred due to hot refueling performed by improperly
trained personnel.

Refueling units should be positioned to ensure adequate
rotor blade clearance. Persons not involved with the
refueling operation should keep clear of the area. Smoking
must be prohibited in and around the aircraft during all
refueling operations.

If operations dictate that the pilot must leave the helicopter
during refueling operations, the throttle should be rolled
back to flight idle and flight control friction firmly applied to
prevent uncommanded control movements. The pilot should
be thoroughly trained on setting the controls and egressing/
ingressing the helicopter.

Safety in and Around Helicopters

People have been injured, some fatally, in helicopter accidents
that would not have occurred had they been informed of the
proper method of boarding or deplaning.

[Figure 8-3]

properly briefed passenger should never be endangered by
a spinning rotor. The simplest method of avoiding accidents
of this sort is to stop the rotors before passengers are boarded
or allowed to depart. Because this action is not always
practicable, and to realize the vast and unique capabilities
of the helicopter, it is often necessary to take on passengers
or have them exit the helicopter while the engine and rotors
are turning. To avoid accidents, it is essential that all persons
associated with helicopter operations, including passengers,
be made aware of all possible hazards and instructed how
those hazards can be avoided.

Ramp Attendants and Aircraft Servicing Personnel

These personnel should be instructed as to their specific
duties and the proper method of fulfilling them. In addition,
the ramp attendant should be taught to:

1. Keep passengers and unauthorized persons out of the

helicopter landing and takeoff area.

2. Brief passengers on the best way to approach and

board a helicopter with its rotors turning.

Persons directly involved with boarding or deplaning
passengers, aircraft servicing, rigging, or hooking up external
loads, etc., should be instructed as to their duties. It would be
difficult, if not impossible, to cover each and every type of
operation related to helicopters. A few of the more obvious
and common ones are covered below.

Passengers

Passengers increase the responsibility, workload, and risk for
the pilot. The workload and distractions seem magnified to
inexperienced pilots while they are developing confidence and
ability to operate in the aviation environment. Inexperienced
pilots should consider building up their passenger carrying
experience while remaining in good flying conditions and
in a familiar area.

All persons boarding a helicopter while its rotors are turning
should be briefed on the safest means of doing so. The pilot
in command (PIC) should always brief the passengers prior
to engine start to ensure complete understanding of all
procedures. The exact procedures may vary slightly from
one helicopter model to another, but the following should
suffice as a generic guide.

When boarding—

1.   Stay away from the rear of the helicopter.
2.   Approach or leave the helicopter in a crouching manner.
3.   Approach from the side of the helicopter but never

out of the pilot’s line of vision. Certain rotor system
designs allow for rotor blades to pass closer to the
ground towards the front of the helicopter. For that
reason, it is generally accepted for personnel to
approach from the side of the helicopter. Helicopters
designed to be loaded from the rear require personnel
to exercise extreme caution due to tailrotor hazards.

4. Carry tools horizontally, below waist level—never

upright or over the shoulder.

5. Hold firmly onto hats and loose articles.
6. Never reach up or dart after a hat or other object that

might be blown off or away.

7. Protect eyes by shielding them with a hand or by

8-6

squinting.

8. If suddenly blinded by dust or a blowing object, stop

and crouch lower; better yet, sit down and wait for help.

9. Never grope or feel your way toward or away from

the helicopter.

10. Protect hearing by wearing earplugs or earmuffs.

Since few helicopters carry cabin attendants, the pilot must
conduct the pretakeoff and prelanding briefings, usually
before takeoff due to noise and cockpit layout. The type
of operation dictates what sort of briefing is necessary. All
briefings should include the following:

1. Passengers should be briefed and understand the proper

use of seatbelts, doors, and headsets/intercom system.

2. The safe entry and exit paths (away from the tail rotor

and within the pilot’s view).

3. If possible, remove front passenger flight controls and

ensure all passenger personal items, such as cameras
and mobile phones are secure.

4. For over water flights, the location and use of flotation

gear and other survival equipment that are onboard.
Pilot instructions should include how and when to exit
the helicopter should ditching or a water landing occur.

5. For flights over rough or isolated terrain, the pilot

should brief all occupants regarding the location of
maps and survival equipment.

6. Passengers should be informed as to what actions and

precautions to take in the event of an emergency, such
as the body position for best spinal protection against
a high vertical impact (erect with back firmly against
the seat back); and when and how to exit. Ensure
that passengers are aware of the location of the fire
extinguisher, survival equipment and, if equipped,
how to use and locate the Emergency Position
Indicator Radio Beacon (EPIRB).

When passengers are approaching or leaving a helicopter
that is sitting on a slope with the rotors turning, they should
approach and depart downhill. This affords the greatest
distance between the rotor blades and the ground. If this
involves walking around the helicopter, they should always
go around the front—never the rear.

Pilot at the Flight Controls

Many helicopter operators have been lured into a “quick
turnaround” ground operation to avoid delays at airport
terminals and to minimize stop/start cycles of the engine.
As part of this quick turn-around, the pilot might leave
the cockpit with the engine and rotors turning. Such an

operation can be extremely hazardous if a gust of wind
disturbs the rotor disk, or the collective flight control
moves causing lift to be generated by the rotor system.
Either occurrence may cause the helicopter to roll or pitch,
resulting in a rotor blade striking the tail boom or the
ground. Good operating procedures dictate that, generally,
pilots remain at the flight controls whenever the engine is
running, and the rotors are turning.

If operations require the pilot to leave the cockpit to refuel,
the throttle should be rolled back to flight idle and all
controls firmly frictioned to prevent uncommanded control
movements. The pilot should be well trained on setting
controls and exiting the cockpit without disturbing the flight
or power controls.

After Landing and Securing

When the flight is terminated, park the helicopter where
it does not interfere with other aircraft and is not a hazard
to people during shutdown. For many helicopters, it is
advantageous to land with the wind coming from the right
over the tail boom (counterrotating blades). This tends to
lift the blades over the tail boom but lowers the blades in
front of the helicopter. This action decreases the likelihood
of a main rotor strike to the tail boom due to gusty winds.
Rotor downwash can cause damage to other aircraft in close
proximity, and spectators may not realize the danger or see the
rotors turning. Passengers should remain in the helicopter with
their seats belts secured until the rotors have stopped turning.
During the shutdown and postflight inspection, follow the
manufacturer’s checklist. Any discrepancies should be noted
and, if necessary, reported to maintenance personnel.

Chapter Summary

This chapter explained the importance of preflight and
safety when conducting helicopter ground operations. Proper
procedures for engine run-up, refueling, and ground safety
were detailed and the responsibilities of the pilot when
maintenance issues occur before flight.

9-2

Where a technique differs, it is noted. For example, a power
increase on a helicopter with a clockwise rotor system
requires right antitorque pedal pressure instead of left pedal
pressure. In many cases, the terminology “apply proper pedal
pressure” is used to indicate both types of rotor systems.
However, when discussing throt tle coordination to maintain
proper rotations per minute (rpm), there is no differentiation
between those helicopters with a gov ernor and those without.
In a sense, the governor is doing the work for you. In addition,
instead of using the terms “collective pitch control” and
“cyclic pitch control” throughout the chapter, these controls
are referred to as just “collective” and “cyclic.”

Because helicopter performance varies with weather
conditions and aircraft loading, specific nose attitudes and
power settings are not detailed in this handbook. In addition,
this chapter does not detail every attitude of a helicopter in
the various flight maneuvers, nor every move that must be
made in order to perform a given maneuver.

When a maneuver is presented, there is a brief description,
followed by the technique to accomplish the maneuver. In
most cases, there is a list of common errors at the end of the
discussion.

The Four Fundamentals

There are four fundamentals of flight upon which all
maneuvers are based: straight-and-level flight, turns, climbs,
and descents. All controlled flight maneuvers consist of one
or more of these four fundamentals of flight. If a student pilot
is able to perform these maneuvers well, and the student’s
proficiency is based on accurate “feel” and control analysis
rather than mechanical movements, the ability to perform
any assigned maneuver is only a matter of obtaining a clear
visual and mental conception of it. The flight instructor must
impart a good knowledge of these basic elements to the
student and must combine them and plan their practice so that
proper performance of each is instinctive without conscious
effort. The importance of this to the success of flight training
cannot be overemphasized. As the student progresses to
more complex maneuvers, discounting any difficulties in
visualizing the maneuvers, most student difficulties are
caused by a lack of training, practice, or understanding of the
principles of one or more of these fundamentals.

Guidelines

Good practices to follow during maneuvering flight include:

1. Move the cyclic only as fast as trim, torque, and rotor

speed can be maintained. When entering a maneuver
and the trim, rotor, or torque reacts quicker than
anticipated, pilot limitations have been exceeded. If
continued, an aircraft limitation will be exceeded.

Perform the maneuver with less intensity until all
aspects of the machine can be controlled. The pilot
must be aware of the sensitivity of the flight controls
due to the high speed of the main rotor.

2. Anticipate changes in aircraft performance due to

loading or environmental condition. The normal
collective increase to check rotor speed at sea level
standard (SLS) may not be sufficient at 4,000 feet
pressure altitude (PA) and 95 °F.

3. The following flight characteristics may be expected

during maneuvering flight and will be discussed and
demonstrated by your Flight Instructor:
• Left turns, torque increases (more antitorque).

This applies to most helicopters, but not all.

• Right turns, torque decreases (less antitorque).

This applies to most helicopters, but not all.

• Application of aft cyclic, torque decreases and

rotor speed increases.

• Application of forward cyclic (especially when

immediately following aft cyclic application),
torque increases and rotor speed decreases.

•

Always leave a way out.

•

Know where the winds are.

•

Engine failures can occur during power changes
and cruise flight. One possible cause of engine
failure during cruise flight can be attributed to the
pilot ignoring carburetor air temperatures, which
could lead to carburetor icing and, subsequently,
engine failure.

• Crew coordination is critical. Everyone needs

to be fully aware of what is going on, and each
crewmember has a specific duty.

• In steep turns, the nose drops. In most cases,

energy (airspeed) must be traded to maintain
altitude as the required excess engine power may
not be available (to maintain airspeed in a 2G/60°
turn, rotor thrust/engine power must increase by
100 percent). Failure to anticipate this at low
altitude endangers the crew and passengers.
The rate of pitch change is proportional to gross
weight and density altitude.

•

Normal helicopter landings usually require high
power settings, with terminations to a hover
requiring the highest power setting.

• The cyclic position relative to the horizon

determines the helicopter’s travel and attitude.

9-3

A O M

CLUTCH

TEMP

CHIP

STARTER

CHIP

lOW

FUEL

LOW

RPM

FUEL

245

II5

I00

OBS

NAV

VERTICAL SPEED

100 FEET PER MINUTE

DOWN

2 MIN TURN

DC ELEC

30.0

29.9

29.8

I00

FEET

CALIBRATED

20,000 FEET

ALT

20 20

I0 I0

20 20

TEST

STBY PWR

IN Hg

ALg.

MANFOLD

PRESS

20 30

100

0 10

MPH

KNOTS

120

110

100

110

100
90
80
70

110

100

90
80
70

E R

%RPM

Figure 9-1.

Maintain straight-and-level flight by adjusting the rotor

tip-path plane forward but adjusting the collective as necessary to
maintain a constant airspeed and altitude. The natural horizon line
can be used as an aid in maintaining straight-and-level flight. If
the horizon line begins to rise, slight power may be required or the
nose of the helicopter may be too low. If the horizon line is slowly
dropping, some power may need to be taken out or the nose of the
helicopter may be too high, requiring a cyclic adjustment.

Straight-and-Level Flight

Straight-and-level flight is flight in which constant altitude
and heading are maintained. The attitude of the rotor disk
relative to the horizon determines the airspeed. The horizontal
stabilizer design determines the helicopter’s attitude when
stabilized at an airspeed and altitude. Altitude is primarily
controlled by use of the collective.

Technique

To maintain forward flight, the rotor tip-path plane must
be tilted forward to obtain the necessary horizontal thrust
component from the main rotor. By doing this, it causes the
nose of the helicopter to lower which in turn will cause the
airspeed to increase. In order to counteract this, the pilot
must find the correct power setting to maintain level flight by
adjusting the collective.

[Figure 9-1]

The horizontal stabilizer

aids in trimming the helicopter about its transverse, horizontal
axis, and reduces the amount of nose tuck that would occur.
On several helicopters, it is designed as a negative lift airfoil,
which produces a lifting force in a downward direction.

When in straight-and-level flight, any increase in the
collective, while holding airspeed constant, causes the
helicopter to climb. A decrease in the collective, while holding
airspeed constant, causes the helicopter to descend. A change
in the collective requires a coordi nated change of the throttle
to maintain a constant rpm. Additionally, the antitorque pedals
need to keep the helicopter in trim around the vertical axis.

To increase airspeed in straight-and-level flight, apply
forward pressure on the cyclic and raise the collective as
necessary to maintain altitude. To decrease airspeed, apply
rearward pressure on the cyclic and lower the collective, as
necessary, to maintain altitude.

Although the cyclic is sensitive, there is a slight delay in
control reaction, and it is necessary to antici pate actual
movement of the helicopter. When making cyclic inputs to
control the altitude or airspeed of a hel icopter, take care not
to overcontrol. If the nose of the helicopter rises above the
level-flight attitude, apply forward pressure to the cyclic to
bring the nose down. If this correction is held too long, the
nose drops too low. Since the helicopter continues to change
attitude momentarily after the controls reach neutral, return
the cyclic to neutral slightly before the desired attitude is
reached. This principle holds true for any cyclic input.

Since helicopters are not very stable, but are inherently very
controllable, if a gust or turbulence causes the nose to drop,
the nose tends to continue to drop instead of returning to a
straight-and-level attitude as it would on a fixed-wing aircraft.
Therefore, a pilot must remain alert and fly the helicop ter
at all times.

Common Errors

1. Failure to trim the helicopter properly, tending to hold

antitorque pedal pressure and opposite cyclic. This is
commonly called cross-controlling.

2. Failure to maintain desired airspeed.
3. Failure to hold proper control position to main tain

desired ground track.

4. Failure to allow helicopter to stabilize at new airspeed.

Turns

A turn is a maneuver used to change the heading of the
helicopter. The aerodynamics of a turn were previously
discussed in Chapter 2, Aerodynamics of Flight.

Technique

Before beginning any turn, the area in the direction of the
turn must be cleared not only at the helicopter’s alti tude, but
also above and below. To enter a turn from straight-and-level
flight, apply sideward pressure on the cyclic in the direction
the turn is to be made. This is the only control movement
needed to start the turn. Do not use the pedals to assist the
turn. Use the pedals only to compensate for torque to keep
the helicopter in trim around the vertical axis.

[Figure 9-2]

Keeping the fuselage in the correct streamlined position
around the vertical axis facilitates the helicopter flying
forward with the least drag.

Trim is indicated by a yaw string

in the center, or a centered ball on a turn and slip indicator. A
yaw string (also referred to as a slip string) is a tool used to
indicate slip or skid during flight. It is simply a string attached
to the nose or canopy of an aircraft so that it is visible to the
pilot during flight. The string measures sideslip and offers
a visual cue to the pilot in order to make yaw corrections.

Helicopter Flying Handbook (2019) - page 3