TM 1-1520-238-10
Change 10
9-10.1/(9-10.2 blank)
9.5.8 Engine Alternator Malfunction.
CAUTION
– Complete failure of the alterna-
tor or of the winding provided NG
speed indicated signal will activate
the ENG OUT warning light and au-
dio. The pilot shall check the Nr
gauge indication and be prepared to
carry out the actions for a high side
failure. Thereafter, reference TGT
and OIL PSI ENG, along with FUEL
PSI ENG and OIL PSI NOSE GRBX
segment lights of the affected en-
gine.
– Following a complete failure
of an alternator, operation of the cor-
responding engine and all indica-
tions from engine instruments will
be normal, except that NG indica-
tions will be lost and the corre-
sponding ENG OUT warning light
and audio will be activated.
The engine alternator has three windings, providing
power for engine ignition, aircraft NG speed indication,
and electrical control system operation. A failure of the
ignition winding would result in loss of electrical power to
the ignition circuitry which would be detected by inability
to start the engine. A failure of the winding providing NG
speed indication signal would not affect actual engine
operation; however, the pilot would have no NG indica-
tion. A failure of the winding providing electrical power to
the engine ECU
is the most severe and requires im-
mediate action by the pilot. The immediate indication to
the pilot may be the affected engine accelerating to
maximum power. There will also be a loss of Np and
torque indication. If this failure is due to a complete loss
of the alternator, then no NG indication will be present
either. The engine TGT will still be indicating because it
is not acted upon by the ECU
; however, TGT limiting
will no longer be available. Np overspeed protection will
be present because aircraft power is supplied for that
function. If an alternator failure is suspected and the af-
fected engine accelerates to maximum power, proceed
as in HIGH RPM ROTOR (warning light ON) NP FAILED
HIGH.
WARNING
If night or simulated night NOE, reac-
tion to the following malfunctions must
be immediate. Exit the NOE environ-
ment immediately.
9.5.9 ENGINE COMPRESSOR STALL.
An engine compressor stall is normally recognized by a
noticeable bang or popping noise and possible aircraft
yaw. These responses are normally accompanied by a
rapid increase in TGT and fluctuations in NG, torque,
and Np readings for the affected engine. In the event of
a compressor stall:
1. Collective – Reduce.
If condition persists:
2. PWR lever (affected engine) – Retard. (TGT
should decrease.)
3. PWR lever (affected engine) – FLY.
If stall condition reoccurs:
4. PWR lever (affected engine) – IDLE.
5. LAND AS SOON AS PRACTICABLE.
