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_________ Subtask 71-00-00-869-113
A. Do these procedures as necessary.
(1) Hot Start during the Manual Start Procedure
(a) During a hot start, the engine light-off but the exhaust gas temperature goes over the limit very quickly.
(b) A possible hot start can be identified by an unusually fast EGT increase after engine light-off. The EGT will most likely go higher than the limits if the start is not aborted in time. A hot start can be anticipated and aborted before the 725 deg.C (1337 deg.F) limit is gone beyond.
(c) Hot starts can be caused by the conditions which follow:
(d) Hot start procedure 1 If the EGT goes near the limits, use the procedure that
1_ A compressor stall.
2_ A low starter air pressure. This can cause the N2 to be less
than the amount needed to provide sufficient compressor air
flow.
3_ A faulty starter valve action. This can prevent correct
starter operation.
4_ The starter is stopped too soon.
5_ The incomplete purging of the fuel remaining in the combustion
chamber after an earlier start try.
6_ Foreign Object Damage (FOD). This can prevent sufficient
engine acceleration and airflow.
7_ A faulty pressurizing valve (hung open). This can cause fuel
to puddle in the combustion chamber before light-off.
8_ Incorrect scheduling of the variable stator vanes (VSV).
_ follows:
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ECES E F 『 E C F M E E E E 56-5B E E E a On the ENG panel 115VU:
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- Set the ENG/MASTER 1(2) switch to OFF.
- Set the ENG/MODE/CRANK/NORM/IGN/START selector switch to CRANK (dry motor the engine for 30 seconds) (Ref. TASK 71-00-00-710-001).
b On the overhead CTL & IND panel 22VU:
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- Release the ENG/MAN START/1(2) pushbutton switch (the ON legend of this pushbutton switch goes off).
c On the ENG panel 115VU:
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- Set the ENG/MODE/CRANK/NORM/IGN/START selector switch to NORM.
2 If the fuel flow during the first start try before light-off
_ was more than 550 pph (249 kg/h), or the maximum motoring speed you were able to reach was less than 20 percent N2, do this before a restart try:
- If the fuel flow was high, do a wet motoring to make sure the flow value was correct (Ref. TASK 71-00-00-710-002).
- If the motoring speed was low, make sure the starter air pressure is correct. Also make sure that the starter valve operates normally, and the engine core turns freely.
(2) Hung Start during Manual Start Procedure
(a) Hung start
1 During a hung start, the engine lights up but the engine speed
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does not increase.
2 A hung start can be identified by a light-off followed by an
_ unusually slow acceleration and an rpm that stabilizes at less than idle.
3 Hung start can be caused by the conditions which follow:
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(b) Hung start causes
1 The starter air pressure is too low to accelerate the engine
_ to a self-sustaining speed. The starter must help the engine to accelerate to speeds that are more than 40-45 percent N2 for a successful start.
2 FOD to the compressor.
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3 A faulty starter valve.
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ECES E F 『 E C F M E E E E 56-5B E E E 4 A faulty pressurizing valve that is not opening at the
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scheduled fuel pressure setting.
5 Incorrect scheduling of the HP compressor IGV and the variable
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stators.
6 Turbine section damage.
_ 7 A hung start can also be caused by fuel scheduling that is too
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lean or too rich.
a A lean hung start can be identified by a low fuel flow and
_ EGT in low proportion to the fuel flow.
b A rich hung start can be identified by high fuel flow and
_ an EGT increase that may turn into an overtemperature condition, and is most likely caused by a compressor stall.
(c) Hung start procedure 1 A hung start can possibly be corrected by doing one of the
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steps that follow:
a For lean hung starts, increase the starter air pressure or
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windmill N2 speed.
b If a hung start cannot be corrected by the recommended
_ procedure, use the Auto Start procedure as there is automatic cross channel/fault selection (Ref. TASK 71-00-00-710-003).
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