ENGINE COMPRESSOR SURGES (STALLS) (LOUD POPPING NOISE HEARD FROM ENGINE).

TM 9-2835-255-34

3-2. TROUBLESHOOTING - CONTINUED

d. ENGINE - CONTINUED

(2) ES-18. ENGINE COMPRESSOR SURGES

(STALLS) (LOUD POPPING NOISE

HEARD FROM ENGINE).

This section contains troubleshooting to locate and correct the cause (s)

of engine compressor surge (stall). The compressor section delivers air

at a specific pressure to the combustor section. If this air flow is not

maintained, high pressure air in the combustor section will tend to

discharge back into the compressor and cause compressor air flow to

stop . Once pressures have neutralized, compressor airflow will resume

until the compressor/combustor pressure ratio becomes unbalanced again,

repeating the above cycle. This cyclic action can sound like a loud

popping noise. The engine compressor air bleed valve system, variable

inlet guide vane (IGV) system and variable power turbine stator (PTS)

system function to maintain the balanced air pressure ratio. Foreign

object damage (FOD) to compressor blades or vanes will prevent the

compressor section from providing proper air pressure. A faulty air

bleed valve system will not allow air to be bled from the compressor

properly. A faulty IGV system will prevent the proper flow of air

entering the compressor section. A faulty PTS system will prevent the

proper control of airflow through the engine. The art on the following

pages provides an overview of the systems described above. Refer to

these pages along with in-text art while performing troubleshooting.

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