9-8. MINIMUM RATE OF DESCENT – POWER
OFF. The power-off minimum rate of descent is at-
tained at an indicated airspeed of 43 knots and 100%
rotor RPM. Refer to figure 9-2, autorotational glide
characteristics chart.
9-9. MAXIMUM GLIDE DISTANCE – POWER
OFF. T he maximum glide distance is atta ined at
an indicated airspeed of 71 knots to 74 knots and
100% rotor RPM. Refer to figure 9-2 for maximum glide
distance.
9-10. E NGINE FAILURE – HOVER.
A
UTOROTATE.
9-11. ENGINE FAILURE – LOWER ALTITUDE/LOW
AIRSPEED OR CRUISE.
1. A
UTOROTATE.
2. EMER SHUTDOW N. Accomplish during
descent if time permits.
9-12. E NGINE RESTART – DUR ING FLIGHT. After
an engine failure in flight, an engine start m ay be at-
tempted. Because the exact cause of the engine failure
cannot be determined in flight, the decision to attempt
the start will depend on the altitude and time available,
rate of descent, potential landing areas, and crew assis-
tance available. Under ideal conditions, approximately
one minut e is required t o re gain powered flight from the
time the attempted start is begun. If the decision is m ade
to attempt an in-flight start.
1. T
hrottle — Close .
2. Attempt start.
3. LAND AS SO ON AS POSSI BLE.
9-13. ENGINE COMPRESSOR STA LL. Engine
compressor stall may be characterized by a s harp
rumble or a series of loud sharp reports, severe engine
vibration and a rapid rise in TOT depending on the
severity of the surge. After engine compressor stall,
maneuvers requiring rapid or maximum power applica-
tions should be avoided. Should engine compressor
stall occur:
1. C
ollecti ve — Reduce .
2. ENG DEICE and HTR switches — OFF.
3. LAND AS SO ON AS POSSI BLE.
9-14. ENGINE OVERS PEED. Engine overspeed will
be indicated by a right yaw, rapid increase in both rotor
and engine RPM, and an increase in engine and rotor
noise. If an engine overspeed is experienced:
1. C
ollecti ve—Increase to load the rotor
and sustain engine/rotor RPM below the
maximum operating limit.
2. T
hrottl e — Adjust until normal N-2
operating RPM is attained.
3. L
AND AS SOON AS POSSIBLE. Perform
a power-on approach and landing by
controlling the RPM manually with throttle.
e. If RPM cannot be controlled manually:
1. A
UTOROTATE when over a safe landing
area while simultaneously closing the
throttle.
2. E
MER SHUTDOWN. Accomplish d uring
descent if time permits.
9-15. ENGINE UNDERSPEED .
a. If an engine underspeed occurs, the collective
must be adjusted downward to maintain rotor RPM
within limits. If powered flight with rotor in the green can
be accomplished, L
AND AS SOON AS POSSIBLE in
an area that will permit a run-on landing.
b. An engine underspeed below 94% N2 results
in rotor RPM decay below minimum safe limits. Should
this occur:
1. A
UTOROTATE.
2. EMER SHUTDOW N. Accomplish during
descent, if time permits.
9-16. ENGINE SURGES. If surges in engine RPM
are experienced:
1. G
OV RPM switch – INCR for maximum
RPM.
2. T
hrottl e – Adjust to 98% N2.
3. LAND AS SO ON AS POSSI BLE.
If engine surges are not controlled in steps 1. and 2.
above, proceed as follows:
4. A
UTOROTATE – When over safe landing
area.
5. E
MER SHUTDOWN. Accomplish d uring
descent if time permits.
9-17. ROTORS, TRANSMISSION AND DRIVE
SYSTEMS MALFUNCTIONS.
9-18. TAIL ROTOR FAILURE AND DIRECTIONA L
CONTROL MALFUNCTIONS. Because of the many
different malfunctions that can occur, it is not possible
to provide a solution for every emergency. The suc-
cess in coping with the emergency depends on quick
analysis of the condition and selection of the proper
emergency procedure. The following is a discussion
of some types of malfunctions, probable effects, and
corrective actions.
9-19. COMPLETE LOSS OF TAIL ROTOR
THRUST. This situation involves a break in the drive
Change 14 9-7
TM 55-1520-228-10
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