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A B747 flight crew returned to their departure airport when unable to resolve a leading edge flap disagreement light anomaly which occurred some 90 minutes after takeoff.
| Attributes | |
| ACN | 924697 |
| Time | |
| Date | 201012 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZZ.ARTCC |
| State Reference | FO |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | B747 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Flap Control (Trailing & Leading Edge) |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Inflight Event / Encounter Fuel Issue |
Narrative:
90 minutes after takeoff the right wing leading edge #4 in transit light illuminated on pilot's and flight engineer's panels. We performed the 'leading edge flap disagreement light on (amber)' abnormal checklist but the #4 leading edge device failed to retract. We called company operations and ATC and requested an air turn back to our departure airport; which we performed after receiving clearance from ATC.we looked at cruise charts and holding speeds in order to slow aircraft down to 275 KTS. After doing so the leading edge amber lights went out. We left the arming and directional switches in selected position and dumped 55;000 pounds of fuel enroute to reduce landing weight to 630;000.on approach we slowed to 250 KTS; placed the arming and directional switches to off and selected flaps 1. All #2 and #4 leading edge devices fully extended. We then selected flaps 5 and all #1 and #3 leading edge flaps extended normally. We decided that the first officer would perform a normal flap 30 landing with the captain and engineer monitoring the aircraft condition; approach and landing. We then performed a normal flap 30 landing. The age; number of cycles; and time on the airframe and associated parts probably had a hand in the reliability of the aircraft's systems.
Original NASA ASRS Text
Title: A B747 flight crew returned to their departure airport when unable to resolve a leading edge flap disagreement light anomaly which occurred some 90 minutes after takeoff.
Narrative: 90 minutes after takeoff the right wing Leading Edge #4 in transit light illuminated on pilot's and flight engineer's panels. We performed the 'Leading Edge Flap Disagreement Light ON (Amber)' Abnormal Checklist but the #4 Leading Edge device failed to retract. We called Company Operations and ATC and requested an air turn back to our departure airport; which we performed after receiving clearance from ATC.We looked at cruise charts and holding speeds in order to slow aircraft down to 275 KTS. After doing so the leading edge amber lights went out. We left the Arming and Directional switches in selected position and dumped 55;000 LBS of fuel enroute to reduce landing weight to 630;000.On approach we slowed to 250 KTS; placed the arming and directional switches to off and selected flaps 1. All #2 and #4 leading edge devices fully extended. We then selected flaps 5 and all #1 and #3 leading edge flaps extended normally. We decided that the First Officer would perform a normal flap 30 landing with the Captain and Engineer monitoring the aircraft condition; approach and landing. We then performed a normal flap 30 landing. The age; number of cycles; and time on the airframe and associated parts probably had a hand in the reliability of the aircraft's systems.
Data retrieved from NASA's ASRS site as of April 2012 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.