Narrative:

Aircraft was dispatched with APU fuel heat inoperative. On taxi out, crew advised dispatcher and maintenance that APU had overspd and needed approval. Dispatcher conferred with maintenance and agreed to use MEL relief for the APU. Some question later arose as to the legality of inoping the APU since the MEL for the APU fuel heat stipulates the APU must operate normally. I believe, as does maintenance, the intent of the statement was to allow operation of the APU with the fuel heat inoperative. The aircraft was taken OTS at the destination and maintenance ferried for repair of the APU. While I believe no violation occurred and the intent of the MEL was followed, the interpretation of the MEL seems misleading and is currently under scrutiny by flight operations and maintenance. Callback conversation with reporter revealed the following information: reporter stated the aircraft was a B737-200 and reported the APU overspd light was illuminated. The reporter said the aircraft had an open deferred item on the APU fuel heater which stated 'may be inoperative provided the APU operates normally.' the reporter said the problem was the overspd light on is not considered a normally operating APU and is it the intent of the MEL to allow ground operation if the automatic shutdown system operates normally. The reporter stated maintenance advised the aircraft to return to the gate to reset the overspd warning and if reset ok, then dispatch with normal APU operation. The reporter said the deferring of the APU as inoperative per the MEL was chosen and the aircraft dispatched.

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Original NASA ASRS Text

Title: A B737-200 ON TAXI OUT RPTS THE APU OVERSPD LIGHT ON. ACFT HAS A DEFERRED ITEM ON THE APU FUEL HEATER INOP. THE DISPATCHER AND MAINT HAVE A PROB INTERPING THE MEL AND RENDER THE APU INOP.

Narrative: ACFT WAS DISPATCHED WITH APU FUEL HEAT INOP. ON TAXI OUT, CREW ADVISED DISPATCHER AND MAINT THAT APU HAD OVERSPD AND NEEDED APPROVAL. DISPATCHER CONFERRED WITH MAINT AND AGREED TO USE MEL RELIEF FOR THE APU. SOME QUESTION LATER AROSE AS TO THE LEGALITY OF INOPING THE APU SINCE THE MEL FOR THE APU FUEL HEAT STIPULATES THE APU MUST OPERATE NORMALLY. I BELIEVE, AS DOES MAINT, THE INTENT OF THE STATEMENT WAS TO ALLOW OP OF THE APU WITH THE FUEL HEAT INOP. THE ACFT WAS TAKEN OTS AT THE DEST AND MAINT FERRIED FOR REPAIR OF THE APU. WHILE I BELIEVE NO VIOLATION OCCURRED AND THE INTENT OF THE MEL WAS FOLLOWED, THE INTERP OF THE MEL SEEMS MISLEADING AND IS CURRENTLY UNDER SCRUTINY BY FLT OPS AND MAINT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE ACFT WAS A B737-200 AND RPTED THE APU OVERSPD LIGHT WAS ILLUMINATED. THE RPTR SAID THE ACFT HAD AN OPEN DEFERRED ITEM ON THE APU FUEL HEATER WHICH STATED 'MAY BE INOP PROVIDED THE APU OPERATES NORMALLY.' THE RPTR SAID THE PROB WAS THE OVERSPD LIGHT ON IS NOT CONSIDERED A NORMALLY OPERATING APU AND IS IT THE INTENT OF THE MEL TO ALLOW GND OP IF THE AUTO SHUTDOWN SYS OPERATES NORMALLY. THE RPTR STATED MAINT ADVISED THE ACFT TO RETURN TO THE GATE TO RESET THE OVERSPD WARNING AND IF RESET OK, THEN DISPATCH WITH NORMAL APU OP. THE RPTR SAID THE DEFERRING OF THE APU AS INOP PER THE MEL WAS CHOSEN AND THE ACFT DISPATCHED.

Data retrieved from NASA's ASRS site as of July 2007 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.