- Date
- August 27, 1990, 10:25 local (17:25 UTC)
- Place
- Los Angeles, CA
- Injuries
- 25 minor, 320 uninjured; on the ground: 2 minor
- Damage
- Minor damage
- Phase of flight
- Landing
- Aircraft
- N174UABoeing 747-422
- Weather
- Visual (VMC) · Day
- Status
- Completed · report December 30, 1992
- Report
- Approved by Office Director
- FAA report
- 19900827040239I
- Case key
- 26662
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
The failure of the manufacturer to ensure that the landing gear selector valves and their associated drum link assemblies were properly installed prior to delivery of the aircraft. A factor in the accident was the lack of information available to the crew concerning the secondary alternate gear extension procdure.
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 crew noted that the nose and main body gear indicated up and locked after normal gear extension. The crew used the alt gear extension procedure, which was unsuccessful. The aircraft landed with the nose and main body gear retracted when the flight reached the min fuel state. Exam of the aircraft revealed that the selector valve for the affected gear was in the up and locked position, and the bolt which connects the valve arm to the cockpit control cable system was missing. The bolt for wing gear selector valve arm was found partially backed out; the nut and cotter pin were missing. The aircraft was delivered to united in jan of 1990 and had 2,952 flt hrs and 402 cycles. Detailed review of the maint records proved that united had not performed any maint on the landing gear system. A second alt gear extension procedure involving de-energizing the hydraulic system for the affected gear is not published in the crew manuals, taught during initial training, nor available on any checklist.
Aircraft
- Registration
- N174UA
- Reported as
- Boeing 747-422
- Category
- Airplane
- Serial number
- 24381
- Airframe hours
- 2,952
- Engine
- P&W JT 4056, 56,000 lbs thrust, turbo fan
- Damage
- Minor damage
- Flight
- Part 121
- Operator
- United Airlines
- Registered owner
- Unknown
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · August 25, 1990 · 31 hours before
- Departed
- ASSY · Sydney, OF
- Destination
- LAX
- Flight plan
- IFR
- Airport
- LAX · Los Angeles Intl., runway 25R, 12,091 × 150 ft, concrete
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
- 57
- Certificate
- Airline transport
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Flight hours
- 18,795 total · 25 in this make and model · 121 in the last 90 days · 42 in the last 30 days · 13 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 250° at 10 knots
- Visibility
- 12 statute miles
- Lowest ceiling
- None
- Temperature
- 75 °F, dew point 55 °F
- Altimeter
- 30.00 inHg
- Observed at
- LAX
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 N174UA · 1
Matched to the same aircraft by N-number and date.