TM55-2840-251-23
Section X ENGINE TESTING (Continued)
1-95 GROUND TESTING OF ENGINE ON MOBILE
TRAILER ASSEMBLY (AVIM) (Cont)
3.c. (Cont)
(1) Hot start. Interturbine temperature limits. If
interturbine temperature is rising rapidly when nearing
1600°F (870°C), a hot start shall be anticipated, and
operator shall abort start to prevent overtemperature of
engine. A hot start may also be caused by a false or a
hung start.
CAUTION
Interturbine temperature may continue to rise
during false start or hung start and operator
shall abort start before interturbine gas
temperatures are exceeded.
(2) False start or hung start. After ignition has
occurred, rpm remains at lower idle speed.
(3) No start. If interturbine temperature gage
does not indicate a rise in temperature, or if there is no
increase in rpm, place fuel cutoff lever to cut-off position
as ignition has not been obtained.
4. Check No. 3 - Part Power Trim Check.
a. Introduction. Prior to trimming, engine must be
brought up to its part power trim output and allowed to run
approximately five minutes to bring the engine to normal
operating temperatures.
b. Part Power Trim Stop. Fuel control units are
calibrated during bench test to insure maximum flow is
obtained. The trim stop must be adjusted to individual
engines on installation to insure maximum power on a
71F (21.C) day. If engine inlet temperature is other than
this, it would not be possible to set the maximum speed
stop without first reaching either an interturbine
temperature or a torque limit. To overcome this, a part
power trim stop is provided. The stop is a movable spacer
placed between gas generator maximum speed (Ng) stop
and power lever anvil, and represents a 1700 rpm (Ng)
speed decrement. This stop is permanently attached to
the fuel control unit and is moved from the stowed
position for engine trimming.
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