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A B737-700 was dispatched in non compliance and operated for 5 weeks with the APU start converter circuit breaker pulled and collared. Previous MEL item cleared but circuit breaker not reset.
| Attributes | |
| ACN | 635863 |
| Time | |
| Date | 200411 |
| Day | Mon |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : maintenance ground : preflight |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| ASRS Report | 635863 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | aircraft equipment problem : less severe maintenance problem : non compliance with mel maintenance problem : improper maintenance non adherence : far non adherence : published procedure |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | none taken : detected after the fact other |
| Consequence | other other |
| Factors | |
| Maintenance | performance deficiency : testing performance deficiency : non compliance with legal requirements |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Flight Crew Human Performance Aircraft Chart Or Publication |
| Primary Problem | Maintenance Human Performance |
Narrative:
I was called out to the aircraft with the pilots reporting the battery was discharging when the APU was being started while AC power was present. On the -700 aircraft, the APU is supposed to use the AC power to power the APU starter if it is present through the start power unit. When no AC power is available, the APU starts with battery power. After investigating, I found the APU start converter circuit breaker pulled and collared on the P-91 panel in the east&east, and determined it was pulled for an APU MEL that was cleared 5 weeks previously. After breaker was reset, the APU started properly without battery discharge. This aircraft flew around for 5 weeks with no flight crew or technicians noticing the anomaly, and in addition, the APU was found to operate normally even though the aforementioned breaker was never reset.
Original NASA ASRS Text
Title: A B737-700 WAS DISPATCHED IN NON COMPLIANCE AND OPERATED FOR 5 WKS WITH THE APU START CONVERTER CIRCUIT BREAKER PULLED AND COLLARED. PREVIOUS MEL ITEM CLRED BUT CIRCUIT BREAKER NOT RESET.
Narrative: I WAS CALLED OUT TO THE ACFT WITH THE PLTS RPTING THE BATTERY WAS DISCHARGING WHEN THE APU WAS BEING STARTED WHILE AC PWR WAS PRESENT. ON THE -700 ACFT, THE APU IS SUPPOSED TO USE THE AC PWR TO PWR THE APU STARTER IF IT IS PRESENT THROUGH THE START PWR UNIT. WHEN NO AC PWR IS AVAILABLE, THE APU STARTS WITH BATTERY PWR. AFTER INVESTIGATING, I FOUND THE APU START CONVERTER CIRCUIT BREAKER PULLED AND COLLARED ON THE P-91 PANEL IN THE E&E, AND DETERMINED IT WAS PULLED FOR AN APU MEL THAT WAS CLRED 5 WKS PREVIOUSLY. AFTER BREAKER WAS RESET, THE APU STARTED PROPERLY WITHOUT BATTERY DISCHARGE. THIS ACFT FLEW AROUND FOR 5 WKS WITH NO FLT CREW OR TECHNICIANS NOTICING THE ANOMALY, AND IN ADDITION, THE APU WAS FOUND TO OPERATE NORMALLY EVEN THOUGH THE AFOREMENTIONED BREAKER WAS NEVER RESET.
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.