Narrative:

After first push out; left generator failed on engine start. Returned to gate and maintenance deferred left generator in accordance with MEL; and accomplished required APU MEL (M) checks and installed placards limiting flight to FL350. Flight re-released with new fuel; load; new papers pulled; departed. CSD (left) disconnected after left engine start in accordance with MEL and mechanics brief. On climbout between FL270 and FL320; APU became erratic then failed. Descent initiated to FL300 to attempt restart (older md-80). Restart attempt unsuccessful. Applicable portions of QRH completed; captain elected to return to departure airport. Weather [was] 95% VMC. Emergency declared with ATC for overweight landing; dispatch notified and normal approach and soft landing accomplished; followed by normal taxi in. Logbook completed for overweight landing (8;500 pounds over maximum landing weight limit) and APU failure. After deplaning a retired captain said he did not hear any of my long winded explanation as to why we were returning (regarding the 2 out of 3 rule regarding electrical power sources and the necessity of our return) over the PA. When I questioned my flight attendant crew; one said she heard my explanation while the other two said they did not. All of them heard the required 'prepare' calls; however; I found this odd as I specifically looked at my blue PA light and my meter deflection while I explained the situation. Re-equipped and re-departed. My suggestion is to not dispatch these older aircraft with only one main engine generator and an APU generator. These older APU's are extremely unreliable at altitude in my experience.

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Original NASA ASRS Text

Title: MD80 Captain reports being dispatched with one generator MEL'd and the APU acting as a replacement power source. During their climb; the APU failed and the flight returned to departure airport.

Narrative: After first push out; left generator failed on engine start. Returned to gate and Maintenance deferred left generator in accordance with MEL; and accomplished required APU MEL (M) checks and installed placards limiting flight to FL350. Flight re-released with new fuel; load; new papers pulled; departed. CSD (left) disconnected after left engine start in accordance with MEL and mechanics brief. On climbout between FL270 and FL320; APU became erratic then failed. Descent initiated to FL300 to attempt restart (older MD-80). Restart attempt unsuccessful. Applicable portions of QRH completed; Captain elected to return to departure airport. Weather [was] 95% VMC. Emergency declared with ATC for overweight landing; Dispatch notified and normal approach and soft landing accomplished; followed by normal taxi in. Logbook completed for overweight landing (8;500 LBS over maximum landing weight limit) and APU failure. After deplaning a retired Captain said he did not hear any of my long winded explanation as to why we were returning (regarding the 2 out of 3 rule regarding electrical power sources and the necessity of our return) over the PA. When I questioned my Flight Attendant crew; one said she heard my explanation while the other two said they did not. All of them heard the required 'prepare' calls; however; I found this odd as I specifically looked at my blue PA light and my meter deflection while I explained the situation. Re-equipped and re-departed. My suggestion is to not dispatch these older aircraft with only one main engine generator and an APU generator. These older APU's are extremely unreliable at altitude in my experience.

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.