HEADQUARTERS OH-58A, Technical Manual

Page: 265 / 292

(1) Varying degrees of right yaw depending on
power applied and airspeed at time of failure.
(2) Forward CG shift.
b. Procedure:
(1) Enter autorotative descent (power off).
(2) Maintain airspeed above minimum rate of
descent airspeed.
(3) If run-on landing is possible, complete au-
torotation with a touchdown airspeed above effective
translational lift.
(4) If run-on landing is not possible, start to
decelerate from about 75 feet altitude, so that forward
groundspeed is at a minimum when the helicopter
reaches 10 to 20 feet; execute the touchdown with a
rapid collective pull just prior to touchdown in a level
attitude with minimum ground run.
9-22. LOSS OF TAIL ROTOR EFFECTIVENESS
(LTE). This is a situation involving a loss of effective
tail rotor thrust without a break in the drive system which
cannot be stopped with full left pedal application. If LTE
is experienced, simultaneously:
1. Pedal - Full Left.
2. Cyclic - Forward.
3. As recovery is effected, adjust controls for
normal fl ight.
Collective reduction will aid In arresting the yaw
rate; however, if a rate of descent has been es-
tablished, collective reduction may increase the
rate of descent to an excessive value. The re-
sultant large and rapid Increase in collective to
prevent ground or obstacle contact may further
increase the yaw rate, decrease the rotor RPM
and cause an overtorque and/or over-temper-
ature condition. Therefore, the decision to re-
duce collective must be based on the pilot as-
sessment of the altitude available for recovery.
If spin cannot be stopped and crash is imminent, an au-
torotation may be the best course of action. Maintain
full left pedal until the spin stops, then adjust to maintain
heading.
9-23. MAIN DRIVESHAFT FAILURE. A failure of the
main driveshaft will be indicated by a sudden increase
in engine RPM, decrease in rotor RPM, left yaw and
activation of the low RPM audio, and illumination of the
ROTOR RPM warning light. A transient overspeed of
N1 and N2 may occur but will stabilize. In the event of
main driveshaft failure:
1. AUTOROTATE - Establish a power-on
autorotational glide. The engine must
continue to operate at normal operating
RPM in order to provide tail rotor control.
2. EMER SHUTDOWN after landing.
9-24. CLUTCH FAILS TO DISENGAGE. A clutch
failing to disengage in fl ight will be indicated by the
rotor RPM decaying with engine RPM as the throttle
is reduced to the engine idle position when entering
autorotational descent. This condition results in total
loss of autorotational capability. If a failure occurs:
1. Throttle - Open.
2. LAND AS SOON AS POSSIBLE.
9-25. MAST BUMPING.
LAND AS SOON AS POSSIBLE.
9-26. FIRE. The safety of helicopter occupants is the
primary consideration when a fi re occurs; therefore, it is
imperative that every effort be made by the fl ight crew
to put the fi re out. On the ground, it is essential that the
engine be shut down, crew and passengers evacuated
and fi re fi ghting begun immediately. If time permits, a
"MAYDAY" radio call should be made before the electri-
cal power is off to expedite assistance from fi re fi ghting
equipment and personnel. If the helicopter is airborne
when a fi re occurs, the most important single action that
can be taken by the pilot is to land the helicopter.
Toxic fumes of the extinguishing agent may
cause injury, and liquid agent may cause frost-
bite or low temperature burns.
Change 14 9-9
TM 55-1520-228-10