TM55-2840-251-23
Section X ENGINE TESTING (Continued )
1-95
GROUND TESTING OF ENGINE ON MOBILE
TRAILER ASSEMBLY (AVIM) (Cont)
8.c. (Cont)
(4) With the water brake unloaded and oil
temperature at 100F (38C) minimum, observe and
record Ng at idle speed.
(5) Disconnect Py sense tube between
FCU and power turbine governor at the FCU, and check if
Ng drops from the value recorded in subparagraph
8.c.(4), preceding. Reconnect Py sense tube.
NOTE
During this check, the engine will not respond to
power control lever movement. Leave the controls
in the Lo-idle position.
CAUTION
Carry out this check with zero power
extraction. Should the minimum fuel flow stop
be adjusted too low, an excessive drop in Ng
will result and the operator must be prepared
to shut down the engine if necessary .
(6) If Ng, with Py sense tube
disconnected, was less than Ng recorded in subparagraph
8.c.(4), then engine was governing at the idle speed
setting and the idle speed may be adjusted in accordance
with subparagraph 8.b.(5).
(7) If Ng, with Py sense tube
disconnected, was the same as Ng recorded in
subparagraph 8.c.(4), then the engine was running on the
minimum fuel flow stop and the idle speed must be
checked as in subparagraph 8.d.
d. Barometric Pressure Below 26.25 in. Hg. At
barometric pressure below 26.25 in. Hg., check idle speed
as follows:
CAUTION
The idle speed must not be adjusted at
barometric pressure below 20.58 in. Hg.
(1) Perform pre-start check (subparagraph 2).
(2) Accomplish satisfactory engine start
(subparagraph 3).
(3) Allow engine to warm up to operating
temperature and allow instruments to stabilize. Record
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