Boeing 747-422 incident near Los Angeles, California, August 27, 1990
On August 27, 1990 at about 5:25 pm local time, a Boeing 747-422, registered N174UA, suffered minor damage in an incident near Los Angeles, California (Los Angeles Intl. airport). It was a flight of an unrecorded kind under scheduled airline rules (Part 121). 23 people had minor injuries; 320 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 27, 1990 · about 5:25 pm local time
- Place
- Los Angeles, California · Los Angeles Intl. · map
- Type
- Incident
- Injuries
- 23 people had minor injuries; 320 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing 747-422 · all 747-422s on the register
- Registration
- N174UA · no longer on the register · serial 24381
- Damage
- Minor damage
- Flight
- Flight of an unrecorded kind · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 18,795 hours in all; 25 in this make and model; 121 in the last 90 days; 42 in the last 30 days
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: unk
The aircraft
- Airframe total time: 2,952 hours
- Last inspection: continuous airworthiness programme, August 25, 1990; 31 hours since
- Maximum gross weight: 870,000 lb
- Seats: 348
- Landing gear: retractable
- Engine: P&W JT 4056 (turbofan); 0 hours total
- Operator: United Airlines
The flight
- Departed from: ASSY Sydney OF at 3:00 am
- Destination: LAX
- Flight plan: IFR
- Runway 25R, 12,091 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 250° at 10 knots
- Visibility: 12 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 55°F (13°C)
- Altimeter: 30.00 inHg
- Observation at 5:25 pm from LAX
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 20 | |||
| Passengers | 23 | 300 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N174UA the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.