Date: 201205
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B747-200
Operator: Air Carrier
Flight plan: IFR
Flight phase: Taxi
Aircraft component: Leading Edge Slat
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Distraction; Time Pressure
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: Crew alerted at hotel at XA:30Z and picked up at XB:30Z. Ground transportation to the airport was a 2-hour car ride prior to flight. Crew arrived at the aircraft at XD:30Z and began preflight. Maintenance had powered all systems to include IRS/FMS equipment. As a precautionary; First Officer powered down IRS and FMS to ensure that when powered up; the IRS got the minimum 12 second warm up prior to turning on the FMS. No problems noted initially. Approximately 20 minutes into preflight Flight Engineer noted inoperative B-loop on #2-engine fire detection system. Flight Engineer called Dispatch and put the write up in the log. While programming FMS #3; First Officer discovered the FMS 3 would not respond to input since it was locked up and unresponsive. First Officer tried unsuccessfully twice to reboot the FMS 3. While troubleshooting the locked up FMS; INU #2 fault light illuminated. In response; we powered down INU #2 and allowed 10-minute cooling/rundown period. First Officer also turned off FMS #2 after storing flight plan. After allotted time; First Officer powered up the INU #2 and then FMS #2 in sequence. No further problems noted. While troubleshooting FMS #3; I discovered that LSK 4L was stuck in detent. I pressed and wriggled the button and it freed the stuck state and the FMS 3 began to work normally. The rest of the preflight uneventful. Before start check was initiated at XE:55Z. We completed checklist and started engines at approximately XF:05Z. As we called for taxi; Flight Engineer discovered the Wing Overheat Light was illuminated (left side). NOTE: This is a repeat write up for this aircraft. Flight Engineer isolated the system to troubleshoot the problem. To avoid damaging the leading edge I had Maintenance clear us for flap extension to 5 degrees and we reconfigured for flap extension. After all LED's extended; LED annunciators illuminated; and the Wing Overheat Light extinguished. We contemplated shutting down engines and giving the aircraft back to Maintenance. After conferring with Maintenance and they said there was no indication of visible leaks on the left wing; we elected to continue in an attempt to keep an on time departure. I instructed Maintenance to stay nearby as we were going to block but might be back if the situation reoccurred. We blocked at XF:15Z and commenced a long taxi towards runway. We purposely delayed setting the flaps in order to see if the Wing Overheat Light would illuminate again with the LED's closed. We taxied slowly and varied power settings while back-taxiing on runway. After 15 minutes and nearing the end of the runway we concluded the Wing Overheat Light would not illuminate again and commenced with the taxi checklist. While running the checklist the LED light extinguished while the flaps were at 10 degrees. All LED's at the Flight Engineer panel were extinguished. We stopped at the end of the back-taxi and began troubleshooting this new issue. We discovered that 6 circuit breakers had popped on the overhead panel. All were associated with LED's and trailing edge flaps. This event prompted us to return to the chocks. We blocked in at XF:55Z and shutdown the engines. We debriefed Maintenance and they began troubleshooting the issue. While looking for bleed air leaks on the wing leading edge; they discovered that an LED [Leading Edge Device] on the right wing was not fully closing during flap retraction and turned their attention towards that issue. We were discussing what to write into the log book regarding the initial turn back problem; but the focus on the problem with the aircraft turned toward the PDU [Power Drive Unit]. It was at this moment crew duty day length versus ZZZZ quiet hours became the controlling issue and would we be able to take care of the PDU issue and get the aircraft back into play. We began looking at performance with a disabled PDU and could we take the aircraft as is. We called Dispatch and determined that we were approaching a critical time point with XXXX base quiet hours being the controlling time. We needed to be blocking out in the next hour or we would have to abort the day and go into crew rest. There was insufficient time to get the PDU; so Dispatch and crew collectively decided to get the aircraft to XXXX before the runway closed and Maintenance could change the PDU there. Maintenance wrote up the PDU and handed me the log book. I read the write up regarding the PDU and accepted that it adequately covered the aircraft issue. We closed up the aircraft and blocked out at XJ:50Z and flew a speed averaging Mach .855. We landed 5 minutes prior to quiet hours commencing. Regarding the block back write up. we were in the process of getting the write up in the forms and a quagmire of distractions became the main focus. Maintenance turned their attention toward the PDU and were diligently trying to resolve that issue. I and my crew had devoted our attention towards how to safely and legally get the aircraft moving again. We did not intentionally ignore the block back problem. I accepted the fact that Maintenance had addressed our issue and credited them with properly documenting the problem. Due to the time constraint I didn't focus the due detail needed in the scripting of the issue to include the popped circuit breakers. Multiple maintenance issues coupled with XXXX runway quiet hours controlling departure time. An unmeasurable level of mild fatigue may have contributed to missing details regarding a write up. Ground transportation into a trip during adverse operating hours contributed to various; yet unmeasurable levels of fatigue that could have contributed to missing something as mundane as a write up detail. (Don't ground trans into the beginning of a trip. Ground trans the crew the day before and have them rest on location. Ground trans at the beginning of a trip contributes not only to consuming crew duty day; but adds to unnecessary fatigue that can affect crew decision making. Ground trans at the end of a trip is not a performance issue; but merely a contract issue.) Multiple maintenance complications (6 total) contributed to a constant myriad of distractions to the crew in the attempt to achieve an on-time takeoff. (There is no correction to how an aircraft is going to break down--only the ability to understand that each distraction will sequentially break down the operation of an on-time takeoff) Maintenance crew turning their primary focus towards the PDU problem and departing the issue of popped circuit breakers lead us to believe that the problems were interactive and collective. Wing overheat; LED popped circuit breakers; and PDU were all associated with the area of the manifold at the leading edge of the wing; so we had no way of knowing whether the problems were related or not (Maintenance should focus the initial problem on the issue that directed the turnback and save subsequent issues for after the initial problem is resolved. We should have written the popped circuit breakers up immediately and not let ourselves get distracted by all of the other issues until the write up was in the logbook.) Time constraint of XXXX runway closure directed the focus onto the importance of getting the aircraft moving soon or the crew would have to abort the launch and head to the hotel. Stuff happens and that's the way it is. CRM keeps these aircraft moving safely and it's not just for aircrew.




Synopsis: B747 Captain reports tripped circuit breakers associated with high lift devices during taxi out and returns for maintenance. A Wing Overheat Light had been experienced earlier and was thought to be related and Maintenance discovered a faulty PDU on the right wing. Arrival airport noise curfew and crew duty day began to be issues and the crew ended up departing without entering the tripped circuit breakers in the logbook.