NTSB Identification: SEA04IA175.
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Scheduled 14 CFR (D.B.A. United Airlines)
Incident occurred Friday, August 27, 2004 in Richmond, BC, Canada
Probable Cause Approval Date: 12/28/2004
Aircraft: Boeing 757-200, registration: N526UA
Injuries: 130 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

The flight crew reported hearing a "grinding noise" during initial flap retraction after takeoff. A flight attendant subsequently notified the flight crew that there was a loud "hum and vibration" coming from the right wing. The captain instructed the flight attendant to scan the wing for any anomalies. The flight attendant notified the crew of damage to the wing's leading edge. The flight crew immediately diverted to Seattle, Washington, and performed a normal landing. A post event assessment of the slat by United Airline's engineering staff said "while there is no evidence of bird remains, it is our opinion that the damage was due to impact following takeoff, most likely bird, with subsequent damage caused by flight loads. The crew did not observe birds in the area. The characteristic of the damage does not lend itself to fatigue/delamination of the slat as cause." This incident was delegated to the NTSB by the Canadian TSB.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The slat was impacted by birds after takeoff and subsequently the slat delaminated due to flight loads.

Full narrative available

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