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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Flight crew ascends aircraft to an altitude higher than what is stated for continuous running of an APU in aircraft MEL. Handbook is not read correctly regarding limitation of APU.
| Attributes | |
| ACN | 276161 |
| Time | |
| Date | 199407 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : obk |
| State Reference | IL |
| Altitude | msl bound lower : 37000 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 145 flight time total : 7600 flight time type : 1100 |
| ASRS Report | 276161 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 22000 flight time type : 2500 |
| ASRS Report | 276158 |
| Events | |
| Anomaly | aircraft equipment problem : less severe inflight encounter : weather non adherence : published procedure |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | other |
Narrative:
Operating flight xx slc-jfk at cruise altitude of FL330 with 1 engine generator inoperative and the APU running continuously to supply the other electrical source. Encountered a line of thunderstorms over lake michigan with tops above FL330. We were unable to ascertain the length of the line of thunderstorms so after discussing the APU limitations we requested and climbed to FL370 and clearing the line of thunderstorms and staying in VMC. Unknowingly the MEL restricts the aircraft to FL350, however, our pilot's reference manual states that the APU will supply electrical power to FL420. The APU flamed out just before the start of our descent and with 1 attempted restart during descent between FL350 and FL330 we again tried at FL250 at a slightly reduced speed. This restart was successful. We continued the flight to our destination without any other abnormalities. There seems to be conflicting information contained in various manuals. Supplemental information from acn 276158: in our haste to avoid the WX, the MEL restr to FL350 was momentarily overlooked. If FL350 is the absolute maximum altitude with the above mechanical circumstances, perhaps it should be included in the aircraft limitations section of the pilot's operating manual to help eliminate any confusion in times of busy operational decisions.
Original NASA ASRS Text
Title: FLC ASCENDS ACFT TO AN ALT HIGHER THAN WHAT IS STATED FOR CONTINUOUS RUNNING OF AN APU IN ACFT MEL. HANDBOOK IS NOT READ CORRECTLY REGARDING LIMITATION OF APU.
Narrative: OPERATING FLT XX SLC-JFK AT CRUISE ALT OF FL330 WITH 1 ENG GENERATOR INOP AND THE APU RUNNING CONTINUOUSLY TO SUPPLY THE OTHER ELECTRICAL SOURCE. ENCOUNTERED A LINE OF TSTMS OVER LAKE MICHIGAN WITH TOPS ABOVE FL330. WE WERE UNABLE TO ASCERTAIN THE LENGTH OF THE LINE OF TSTMS SO AFTER DISCUSSING THE APU LIMITATIONS WE REQUESTED AND CLBED TO FL370 AND CLRING THE LINE OF TSTMS AND STAYING IN VMC. UNKNOWINGLY THE MEL RESTRICTS THE ACFT TO FL350, HOWEVER, OUR PLT'S REF MANUAL STATES THAT THE APU WILL SUPPLY ELECTRICAL PWR TO FL420. THE APU FLAMED OUT JUST BEFORE THE START OF OUR DSCNT AND WITH 1 ATTEMPTED RESTART DURING DSCNT BTWN FL350 AND FL330 WE AGAIN TRIED AT FL250 AT A SLIGHTLY REDUCED SPD. THIS RESTART WAS SUCCESSFUL. WE CONTINUED THE FLT TO OUR DEST WITHOUT ANY OTHER ABNORMALITIES. THERE SEEMS TO BE CONFLICTING INFO CONTAINED IN VARIOUS MANUALS. SUPPLEMENTAL INFO FROM ACN 276158: IN OUR HASTE TO AVOID THE WX, THE MEL RESTR TO FL350 WAS MOMENTARILY OVERLOOKED. IF FL350 IS THE ABSOLUTE MAX ALT WITH THE ABOVE MECHANICAL CIRCUMSTANCES, PERHAPS IT SHOULD BE INCLUDED IN THE ACFT LIMITATIONS SECTION OF THE PLT'S OPERATING MANUAL TO HELP ELIMINATE ANY CONFUSION IN TIMES OF BUSY OPERATIONAL DECISIONS.
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.