# NTSB SEA04IA175: Boeing 757-200, N526UA, Richmond, BC, Canada, August 27, 2004 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: August 27, 2004, 11:30 local (18:30 UTC) - Place: Richmond, BC, Canada - Coordinates: 47.444442, -122.331108 - Nearby events: https://openairdocs.org/map.md?lat=47.4444&lon=-122.3311&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 130 uninjured - Status: Completed, report December 28, 2004 - Report: Approved by Office Director - Parties: Seattle, WA - NTSB case key (mKey): 60196 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA04IA175 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/60196/pdf - Page: https://openairdocs.org/ntsb/SEA04IA175 ## Probable cause The slat was impacted by birds after takeoff and subsequently the slat delaminated due to flight loads. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, takeoff - initial climb - object - bird(s) (cause) - flight control,slat - delamination (cause) ## Analysis 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. ## Factual narrative On August 27, 2004, at approximately 1130 Pacific daylight time, a Boeing 757-200, N526UA, received minor damage when the number six leading edge slat wedge was struck by birds during the initial takeoff, and the composite wedge subsequently delaminated over or near Richmond, British Columbia, Canada. The Airline Transport rated pilot and Airline Transport first officer, and an unknown number of additional crew members and passengers were not injured. United Airlines was operating the airplane as flight 426 under Title 14 CFR Part 121. Visual meteorological conditions prevailed for the cross-country passenger flight that originated from Richmond, British Columbia, shortly before the incident and was destined to Chicago, Illinois. An IFR flight plan had been filed. 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. ## Aircraft - Registration: [N526UA](https://openairdocs.org/deregistered/N526UA-2019-02-23), registration cancelled 2019-02-23, S/N 24994, built 1991 (OpenAirDocs) - Reported make and model: Boeing 757-200 - Registry model: [Boeing 757-222](https://openairdocs.org/model/boeing-757-222) (registry code 1384956) (OpenAirDocs) - Registry engine: [Pratt & Whitney PW2040](https://openairdocs.org/engine/pratt-whitney-pw2040) (registry code 52121, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 24994 - Airframe hours: 45605 - Engines: Pratt & Whitney PW2037 37500 horsepower turbo fan - Damage: Minor damage - Flight: Part 121 - Registered owner: United Airlines - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, July 24, 2003, 3,485 hours before - Departed: YVR, Vancouver, BC - Destination: ORD, Chicago, IL - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review January 15, 2004; seat: left; flight hours: 9,170 total, 5,135 in this make and model, 4 in the last 24 hours - Co-pilot; age 36; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review June 15, 2004; seat: right; flight hours: 7,631 total, 3,209 in this make and model, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: 4,000 ft overcast - Temperature: 63 °F, dew point 55 °F - Altimeter: 30.27 inHg - Observed at: SEA ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20040827027429I](https://openairdocs.org/incident/20040827027429I), Aug 27, 2004: Boeing 757222, Minor damage. (-23) Uala flight yvr-ord diverted to seattle-tacoma airport because of a flight control vibration. The aircraft landed without incident. Inspection of the… ## Other investigations on N526UA (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ENG11IA051](https://openairdocs.org/ntsb/ENG11IA051), Sep 26, 2011: Boeing 757-222 (N526UA), Denver, CO, incident, minor damage. Probable cause: **This probable cause was modified on 4/5/2012. Please see the public docket for this accident to view the original probable cause.** The initial damage to the fan blades was caused by the ingestion… - [NTSB WPR11LA300](https://openairdocs.org/ntsb/WPR11LA300), May 31, 2011: Boeing 757-222 (N526UA), Los Angeles, CA, minor damage. Probable cause: The ground crewmembers’ failure to follow proper procedures for removing a stuck or jammed tow bar, which resulted in a ground crew injury. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.