# NTSB FTW94IA077: Fokker F28 MK O100, N1437B, Amarillo, TX, February 1, 1994 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: January 31, 1994, 18:09 local (Feb 1, 1994, 00:09 UTC) - Place: Amarillo, TX - Location: 35.2194° N, 101.7059° W: Placed by OpenAirDocs at RICK HUSBAND AMARILLO INTL (AMA), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=35.2194&lon=-101.7059&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 28 uninjured - Status: Completed, report February 14, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 18937 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW94IA077 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18937/pdf - Page: https://openairdocs.org/ntsb/FTW94IA077 ## Probable cause THE FAILURE OF THE OUTER BEARING DUE TO A LACK OF LUBRICATION. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, takeoff - roll/run - landing gear,axle - separation - landing gear,axle - overtemperature (cause) ## Analysis THE RIGHT MAIN OUTBOARD WHEEL DEPARTED THE AIRCRAFT DURING THE TAKEOFF ROLL. THE TOWER INFORMED THE CREW WHO REPORTED THAT ALL COCKPIT INDICATIONS WERE NORMAL. THE AIRPLANE LANDED AT THE DESTINATION WITHOUT FURTHER INCIDENT. THE OUTBOARD WHEEL BEARING HAD FAILED IN A MANNER THAT THE BEARING CAGE LOST ITS ABILITY TO RETAIN THE ROLLERS. BOTH BOLTS USED TO LOCK THE RETAINER NUT TO THE AXLE WERE IN PLACE. THE WHEEL SPACER WAS SEIZED TO THE INNER RACE OF THE OUTER BEARING AND A DISTINCT RIDGE WAS SEEN ON THE DAMAGED SPACER. NTSB METALLURGICAL EXAMINATION REVEALED THE SPACER WAS ROTATING ON THE AXLE; HOWEVER, THE ORIENTATION OF THE SPACER COULD NOT BE DETERMINED. THE OUTBOARD WHEEL BEARING DISCLOSED EVIDENCE OF OVERHEATING. ## Factual narrative On January 31, 1994, at 1809 central standard time, a Fokker F28 MK 0100, N1437B, sustained minor damage during takeoff from Amarillo, Texas. The crew of four and 24 passengers were not injured. Visual meteorological conditions prevailed for the American Airlines Flight 851 scheduled Title 14 CFR Part 121 operation to Dallas/Fort Worth (DFW) Airport, Texas. An aircraft holding for takeoff on runway 22, reported to the Amarillo Air Traffic Control (ATC) Tower that the right main outboard wheel departed the aircraft. During the departure climb the tower informed the crew. The crew reported to ATC that all cockpit indications were normal and that they would continue the flight to the destination. At 1913, the crew landed the airplane on runway 35 left at the DFW Airport. The airplane was towed to the ramp without further incident. Examination of the aircraft components on February 1, 1994, by company maintenance personnel at DFW, and a Federal Aviation Administration (FAA) airworthiness inspector (enclosed report), revealed the outboard wheel bearing had failed in a manner that the bearing cage lost its ability to retain the rollers. Loss of the cage and rollers allowed clearance for the wheel to migrate outboard. The spacer was fused to the inner race of the outer bearing. On February 2, 1994, the components were reexamined by a FAA inspector and maintenance personnel at the company maintenance and engineering center in Tulsa, Oklahoma. The maintenance director for the facility commented that both bolts used to lock the nut to the axle were in place. On February 16, 1994, the components were examined by the investigator-in-charge, a FAA inspector, a company engineer, and the Aircraft Braking Systems representative. Physical evidence was consistent with a bearing failure. A ridge was seen on the damaged spacer. The engineer (enclosed report) reported that maintenance personnel may have installed the spacer backwards. He further stated that by installing the spacer backwards, damage to the grease seal could have occurred, allowing grease to migrate out, leaving the bearing without sufficient lubricant. The engineer was unable to demonstrate installation of the spacer backwards. The components were forwarded to NTSB metallurgists for examination. Metallurgical examination of the inside diameter of the spacer revealed heavy circumferential score marks indicating the spacer was rotating on the axle. The inside diameter surface also disclosed what appeared to be a ridge. "However, no measurements determining a position of the ridge and, therefore, the orientation of the spacer could be made." Examination of other components from the outboard wheel bearing disclosed evidence of moderate to severe overheating. ## Aircraft - Registration: N1437B (not matched to a registry record) - Reported make and model: FOKKER F28 MK O100 (F28 MK O10) - Category: Airplane - Serial number: 11427 - Airframe hours: 1924 - Engines: Rolls-Royce TAY MK650-15 13320 lbs thrust turbo fan - Damage: Minor damage - Flight: Part 121 - Registered owner: American Airlines, Inc. - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, October 25, 1993, 576 hours before - Departed: AMA - Destination: DFW, DFW AIRPORT, TX - Flight plan: IFR - Airport: AMA, Amarillo International, runway 22, 13,502 × 300 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; flight engineer, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 5,500 total, 433 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 34 °F, dew point 18 °F - Altimeter: 30.00 inHg - Observed at: AMA ## 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 19940131004799I](https://openairdocs.org/incident/19940131004799I), Jan 31, 1994: Fokker F28MK0100, Amarillo, TX, Minor damage. Narrative: on 01/31/94, aala F28MK0100 aircraft, N1437B, operating as flt. 851 from Amarillo, TX to dallas/fort worth, TX had the no.4 wheel assembly fall off… 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.