- Date
- February 13, 1993, 19:15 local (Feb 14, 1993, 02:15 UTC)
- Place
- Grand Junction, CO
- Injuries
- 47 uninjured
- Damage
- No damage
- Phase of flight
- Enroute
- Aircraft
- N508UABoeing 757-222
- Weather
- Visual (VMC) · Night/dark
- Status
- Completed · report November 3, 1993
- Report
- Approved by Office Director
- FAA report
- 19930213006269I
- Case key
- 18252
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
Failure of the left generator control unit (gcu), integrated drive generator (idg), right (side) engine indicator and crew alert system (eicas), and bus tie bar (btb).
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
While cruising at FL390, the autothrottles and autopilot disengaged, the captain's instruments failed, and the cockpit lighting cycled on and off. The left generator light illuminated, the eicas failed, a cyclic banging was heard, and an acrid odor was noticeable. The left ac bus and transfer bus were deenergized and the captain elected to divert to the nearest suitable airport. Post incident investigation disclosed a shorted diode is the left gcu (generator control unit), a defective idg (integrated drive generator), a short in the input power filter in the eicas (engine indicator and crew alert system), and a defective btb (bus tie bar).
Aircraft
- Registration
- N508UA
- Reported as
- Boeing 757-222
- Category
- Airplane
- Serial number
- 24744
- Airframe hours
- 9,483
- Engine
- P&W 2037-717, 37,000 lbs thrust, turbo fan
- Damage
- No damage
- Flight
- Part 121
- Operator
- United Airlines
- Registered owner
- United Airlines
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · January 14, 1993 · 284 hours before
- Departed
- PHL · Philadelphia, PA
- Destination
- LAX · Los Angeles, CA
- Flight plan
- IFR
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 58
- Certificate
- 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
- 11,698 total · 410 in this make and model · 155 in the last 90 days · 59 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Night/dark
- Wind
- 320° at 5 knots
- Visibility
- 30 statute miles
- Lowest ceiling
- None
- Temperature
- 32 °F, dew point 21 °F
- Altimeter
- 30.00 inHg
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N508UA · 2
Matched to the same aircraft by N-number and date.