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the engine will be automatically shut off if TGT exceeds
900 °C during the start sequence. If this occurs, the
PWR lever must be returned to OFF and the ENG
START switch must be placed in IGN OVRD (which
aborts the automatic engine start sequence).
2.30.1 Engine Start Using APU. The APU provides
on-board power for system check by ground personnel.
The APU is capable of driving the main transmission
accessories which include the ac generators, the hydraulic
pumps, and the shaft driven compressor (SDC).
The APU is normally left on during both engine starts,
but it maybe shut down after one engine has reached
100% NP. When NP has reached 100% and the APU
shut down, that engine may be used to drive the SDC
through the transmission and accessory gear train for
starting the second engine. A complete description of
the auxiliary power unit appears in Section XII.
2.30.2 Engine Start Using External Source. An external
air receptacle under the No. 1 engine nacelle
provides an attachment point for an air line to start either
engine from an external source. The assembly contains
a check valve to prevent engine bleed air or SDC
pressurized air from being vented overboard. An external
air source of 40 psig and 30 pounds per minute
(ppm) pressurizes the start system up to the engine
start control valves which requires only that electrical
power be applied for a normal start sequence.
2.30.3 Engine Start Using Engine Bleed Air
Source. When the No. 1 engine is operating and it is
necessary to start the No. 2 engine, bleed air may be
used from the No. 1 engine compressor under certain
circumstances. This technique is not normally used,
however, it is fully automatic, and provides an alternative
starting capability if the SDC shaft fails or if the
SDC throttle valve or surge valve clogs (Section VI,
Pressurized Air System). The starting sequence is the
same as for APU starting, only the source of air to the
start motor is different. When using this technique to
ensure an adequate air pressure and flow to the No. 2
engine starter, collective pitch must be increased to a
value that will increase the NG of the No. 1 engine to a
minimum of 95%.
Change 2 2-29
CAUTION
TM 1-1520-238-10
Figure 2-19. Pilot Emergency Check Overspeed Test Panel Power Lever Quadrant and CPG Power
Lever Quadrant
2.31 ENGINE CONTROL SYSTEM.
The engine control system consists of the engine power
lever quadrant, the engine chop controls, the load demand
system, and the overspeed protection system.
2.31.1 Engine Power (PWR) Lever Quadrants. The
PWR lever quadrants for the pilot and CPG (fig 2-19)
allow either crewmember to manage engine power. The
two quadrant control panels are different, although the
PWR levers are identical. Friction however, can be set
on only the pilot levers. The PWR levers have four detent
positions: OFF, IDLE, FLY and LOCKOUT. The
pilot detent override controls are mechanical while the
CPG’s are electrically operated. Movement of either
PWR lever moves a cable to mechanically shut off fuel
(stop cock) or to set NG speed. For flight, the lever is advanced
to FLY. By moving the PWR lever momentarily
to LOCKOUT, then retarding past FLY, NG speed may
be manually controlled. When the PWR lever is in
LOCKOUT, the TGT limiting system is deactivated,
and TGT must be closely monitored and controlled. The
overspeed protection system is not disabled in the
LOCKOUT position.
Physically confirm that engine chop
collar is seated in its latched/centered
position.
2.31.2 Pilot and CPG Engine Chop Control. The
position of a knurled ring on each collective stick grip
controls engine chop. The ring is placarded UNLATCH,
CHOP and RESET. When the ring is pushed
forward (UNLATCH) and rotated 45° to the right to
CHOP, the speed of both engines is reduced to idle.
This is done by a switch in the grips that cuts out the
power turbine speed reference signals for both engines.
At this time, the ENGINE CHOP warning light will illuminate.
The ENG 1 OUT and ENG 2 OUT lights
and audio will not activate because engine chop activation
disables this feature. The LOW RPM ROTOR
2-30
WARNING
warning light and audio will activate. If the knurled
ring is released after turning to CHOP, it will snap
back to the center position, but the engines will remain
at idle and the ENGINE CHOP warning light will remain
illuminated. Retard both PWR levers to IDLE. If
the knurled ring is then turned 45° to the left to RESET
the engines will perform in accordance with PWR
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