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A B767-300ER had chronic ground APU start problems which always ground checked ok. Technicians found crew start procedure different from technicians start procedure in runup handbook.
| Attributes | |
| ACN | 470724 |
| Time | |
| Date | 200004 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : parked ground : maintenance |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : airframe technician : powerplant |
| Experience | maintenance technician : 14 |
| ASRS Report | 470724 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : published procedure other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : apu control panel other other : person 1 |
| Resolutory Action | none taken : unable |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : manuals performance deficiency : testing performance deficiency : repair performance deficiency : logbook entry performance deficiency : fault isolation |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Flight Crew Human Performance Chart Or Publication Aircraft |
| Primary Problem | Chart Or Publication |
| Situations | |
| Publication | FLIGHT MANUAL APU START |
Narrative:
Air carrier aircraft xyz has had a history since at least mar/00 of the flight crew's not being able to start the APU. Numerous times maintenance checked the ecu with no faults found, and then accomplished a normal start. On apr/mon/00 I looked at the APU for a no start log item. The ecu had no faults and I accomplished several normal starts, so the item was cleared. On apr/thu/00 the aircraft again came to ZZZ with APU start problems. I attempted an APU start and the APU started normally with no faults. In interviewing the crew, I found that flcs use a different procedure for starting the APU. For the flight manual, the crews rotate the start switch to on, wait for the fault light to flash, then rotate to start position and release. Per the handbook which the mechanics use, the start switch is rotated directly to the start position then released. I then attempted an APU start using the pilot's method and was able to duplicate the fault. I then deferred the APU as usable and described the method of starting the APU as called for in the handbook. The APU has consistently started when using the handbook method, and since there is no MEL addressing this, I deferred the APU with no reference. The reason I made a deferral is I felt the start system should be looked into further even though the APU started using the handbook and the handbook takes precedence over the flight manual.
Original NASA ASRS Text
Title: A B767-300ER HAD CHRONIC GND APU START PROBS WHICH ALWAYS GND CHKED OK. TECHNICIANS FOUND CREW START PROC DIFFERENT FROM TECHNICIANS START PROC IN RUNUP HANDBOOK.
Narrative: ACR ACFT XYZ HAS HAD A HISTORY SINCE AT LEAST MAR/00 OF THE FLC'S NOT BEING ABLE TO START THE APU. NUMEROUS TIMES MAINT CHKED THE ECU WITH NO FAULTS FOUND, AND THEN ACCOMPLISHED A NORMAL START. ON APR/MON/00 I LOOKED AT THE APU FOR A NO START LOG ITEM. THE ECU HAD NO FAULTS AND I ACCOMPLISHED SEVERAL NORMAL STARTS, SO THE ITEM WAS CLRED. ON APR/THU/00 THE ACFT AGAIN CAME TO ZZZ WITH APU START PROBS. I ATTEMPTED AN APU START AND THE APU STARTED NORMALLY WITH NO FAULTS. IN INTERVIEWING THE CREW, I FOUND THAT FLCS USE A DIFFERENT PROC FOR STARTING THE APU. FOR THE FLT MANUAL, THE CREWS ROTATE THE START SWITCH TO ON, WAIT FOR THE FAULT LIGHT TO FLASH, THEN ROTATE TO START POS AND RELEASE. PER THE HANDBOOK WHICH THE MECHS USE, THE START SWITCH IS ROTATED DIRECTLY TO THE START POS THEN RELEASED. I THEN ATTEMPTED AN APU START USING THE PLT'S METHOD AND WAS ABLE TO DUPLICATE THE FAULT. I THEN DEFERRED THE APU AS USABLE AND DESCRIBED THE METHOD OF STARTING THE APU AS CALLED FOR IN THE HANDBOOK. THE APU HAS CONSISTENTLY STARTED WHEN USING THE HANDBOOK METHOD, AND SINCE THERE IS NO MEL ADDRESSING THIS, I DEFERRED THE APU WITH NO REF. THE REASON I MADE A DEFERRAL IS I FELT THE START SYS SHOULD BE LOOKED INTO FURTHER EVEN THOUGH THE APU STARTED USING THE HANDBOOK AND THE HANDBOOK TAKES PRECEDENCE OVER THE FLT MANUAL.
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.