B737 flight crew reports turning off the pmc's during descent to help maintenance diagnose a throttl...

Attributes
ACN	909276
Time
Date	201009
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	Turbine Engine
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 203 Flight Crew Type 8000
Person 2
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 226 Flight Crew Type 5212
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

I was the pilot flying. We had maintenance add oil to the left engine in ZZZ. We asked about the large thrust lever split and differing spool up times between the two engines. We were going to do a turn back to ZZZ; so maintenance asked to see what changes would happen to the engine parameters with the pmc's [power management controllers] off. At a steady state cruise; we turned off the pmc's and wrote down the engine parameters. As we were descending; we slowly pulled the thrust levers back and looked at the engine parameters. At approximately fifty percent N1 and passing 32;000 ft; we had two compressor stalls and the left engine rolled back. We quickly turned the pmc's on and went through engine failure shutdown checklist. The engine was still turning with oil pressure; so we elected to restart the left engine with a successful windmill restart. We declared an emergency with the center; landed uneventfully; and taxied to the gate.

Original NASA ASRS Text

Title: B737 Flight Crew reports turning off the PMC's during descent to help Maintenance diagnose a throttle split. At 50% N1 the left engine compressor stalls and rolls back. A successful windmilling restart is accomplished and a normal landing ensues.

Narrative: I was the Pilot Flying. We had maintenance add oil to the left engine in ZZZ. We asked about the large thrust lever split and differing spool up times between the two engines. We were going to do a turn back to ZZZ; so Maintenance asked to see what changes would happen to the engine parameters with the PMC's [Power Management Controllers] off. At a steady state cruise; we turned off the PMC's and wrote down the engine parameters. As we were descending; we slowly pulled the thrust levers back and looked at the engine parameters. At approximately fifty percent N1 and passing 32;000 FT; we had two compressor stalls and the left engine rolled back. We quickly turned the PMC's on and went through Engine Failure Shutdown Checklist. The engine was still turning with oil pressure; so we elected to restart the left engine with a successful windmill restart. We declared an emergency with the Center; landed uneventfully; and taxied to the gate.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

B737 flight crew reports turning off the pmc's during descent to help maintenance diagnose a throttle split. At 50% N1 the left engine compressor stalls and rolls back. A successful windmilling restart is accomplished and a normal landing ensues.