# NTSB FTW95IA049: Boeing B-737-200, N988UA, Springfield, MO, November 18, 1994 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: November 18, 1994, 07:06 local (13:06 UTC) - Place: Springfield, MO - Location: 37.2457° N, 93.3886° W: Placed by OpenAirDocs at SPRINGFIELD-BRANSON NTL (SGF), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=37.2457&lon=-93.3886&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 57 uninjured - Status: Completed, report June 29, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 19260 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW95IA049 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/19260/pdf - Page: https://openairdocs.org/ntsb/FTW95IA049 ## Probable cause THE FAILURE OF EITHER THE INBOARD OR THE OUTBOARD WHEEL BEARING ASSEMBLY DUE TO UNDETERMINED REASONS. ## 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 (cause) - reason for occurrence undetermined ## Analysis DURING THE TAKEOFF ROLL THE LEFT OUTBOARD MAIN WHEEL SEPARATED FROM THE AIRPLANE AXLE. SIX RECOVERED ROLLER BEARINGS HAD SEVERELY DAMAGED ROLLING SURFACES; HOWEVER, ALL THE ROLLER ENDS WERE RELATIVELY FREE OF SCUFFING DAMAGE, WHICH INDICATED ADEQUATE LUBRICATION AND BEARING AXLE PRELOAD. THERE WAS NO INDICATION OF DEFECTS IN THE KEYWAY. THE LEFT HAND AXLE OUTBOARD END HAD SEVERE RESULTANT DAMAGE CONSISTENT WITH A PRIMARY OUTBOARD WHEEL BEARING FAILURE. THE MODE OF THE FAILURE COULD NOT BE DETERMINED. THE AXLE NUT WASHER AND LOCK RING WERE NEVER RECOVERED; HOWEVER, THERE IS PHYSICAL EVIDENCE THAT THEY WERE INSTALLED AT THE TIME OF THE INCIDENT. ## Factual narrative On November 18, 1994, at 0706 central standard time, a Boeing 737-200, N988UA, sustained minor damage during takeoff from Springfield, Missouri. The crew of five and 52 passengers were not injured. Instrument meteorological conditions prevailed for United Airlines Flight 1487, scheduled Title 14 CFR Part 121 service to Denver, Colorado. During interviews and on the enclosed Pilot/Operator report, the information in this paragraph was reported. The crew heard a "slight scraping sound" during the rotation from runway 02. A witness reported to the Springfield Air Traffic Control Tower (ATCT) that airplane debris was found on the runway. The parts were identified as brake assembly components from a Boeing 737 and Springfield ATCT notified the flight crew. The crew reported that all cockpit indications were normal and that they would continue the flight to the destination. Upon arrival at Denver, the tower confirmed the left outboard main wheel was missing. The crew was cleared for a landing on runway 35R and taxied to the ramp without further incident. The airplane components were visually examined on November 23, 1994, at Denver, Colorado, by company maintenance personnel (enclosed statement), a Federal Aviation Administration (FAA) inspector, and a NTSB investigator (enclosed statement). The axle nut retaining ring and nut were not available. Threads on the outer spindle were damaged and "appeared to be rolled outboard." All components were forwarded to the United Airlines facility at San Francisco, California, for further examination. On January 7, 1995, at San Francisco, California, the components (enclosed report) were reexamined at the company engineering facility by company engineers, metallurgists, a FAA inspector, and a NTSB investigator. Six recovered rollers had "severely damaged rolling surfaces; however, all the roller ends were relatively free of scuffing damage, which indicated adequate lubrication and bearing axle preload." There was no indication in or around the keyway of "reportable defect or damage pre-existing the failure event." The left hand axle outboard "end had severe resultant damage consistent with a primary outboard wheel bearing failure." On February 17, 1995, company personnel (statement enclosed) reported that the axle nut lock washer and lock ring were never recovered; however, there is physical evidence "that they were installed at the time of the incident." They further stated that the "primary cause of this incident was a failure of either the inboard or outboard wheel bearing assembly." ## Aircraft - Registration: [N988UA](https://openairdocs.org/deregistered/N988UA-2004-02-13), registration cancelled 2004-02-13, S/N 21750, built 1979 (OpenAirDocs) - Reported make and model: BOEING B-737-200 (B737-200) - Registry model: [Boeing 737-291](https://openairdocs.org/model/boeing-737-291) (registry code 138448W) (OpenAirDocs) - Category: Airplane - Serial number: 73721750 - Airframe hours: 42144 - Engines: P&W JT8D-7B 14000 lbs thrust turbo jet - Damage: Minor damage - Flight: Part 121 - Registered owner: United Airlines - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, December 5, 1993, 2,215 hours before - Departed: SGF, MO - Destination: DEN, DENVER, CO - Flight plan: IFR - Airport: SGF, Sringfield, runway 2, 7,000 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; foreign, commercial, 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: 5,338 total, 542 in this make and model, 5,338 as pilot in command ## Weather - Conditions: Instrument (IMC), Dawn - Wind: 260° at 7 knots - Visibility: 1 statute miles - Lowest ceiling: 100 ft - Temperature: 48 °F, dew point 46 °F - Altimeter: 30.00 inHg - Observed at: SGF ## 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 19941118046779I](https://openairdocs.org/incident/19941118046779I), Nov 18, 1994: Boeing 737291, Denver, CO, Minor damage. Lost left outboard wheel and tire at rotation. Flew to den. Flyby showed wheel gone. Cause wheel bearing failure. 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.