- Date
- April 29, 1991, 12:00 local (16:00 UTC)
- Place
- Churchville, NY
- Injuries
- 102 uninjured
- Damage
- Minor damage
- Phase of flight
- Enroute
- Aircraft
- N148UABoeing 747SP
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 3, 1993
- Report
- Approved by Office Director
- FAA report
- 19910429019829I
- Case key
- 36814
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the incident.
On this page
Probable cause
A failure of the sixth rotating airseal which led to an uncontained engine failure.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The Boeing 747SP had just leveled off at FL350 and was accelerating from m.81 to m.85. During the acceleration, a vibration was felt in the cockpit and cabin. No abnormal engine readings were observed. The vibration lasted for about 2 minutes and was followed by a loud bang heard in the cockpit. The number two engine revealed a failed sixth rotating airseal. Metallurgical examination of failed airseal showed features typical of overstress with no indication of preexisting cracks.
Aircraft
- Registration
- N148UA
- Reported as
- Boeing 747SP
- Category
- Airplane
- Serial number
- 21648
- Engine
- P&W JT9D-7ASP, turbo fan
- Damage
- Minor damage
- Flight
- Part 121
- Operator
- United Airlines
- Registered owner
- United Airlines
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · January 2, 2000
- Departed
- EWR · Newark, NJ
- Destination
- TYO · Tokyo, Japan
- Flight plan
- IFR
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 52
- Certificate
- Airline transport
- Airplane ratings
- Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 16,202 total · 51 in the last 90 days
Weather
- Conditions
- Visual (VMC) · Day
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.