Boeing 757-222 N551UA

Summary

On 11 January 2003 at about 07:45 local time, a Boeing 757-222 registered N551UA, operated by United Airlines, was involved in an incident near Salt Lake City, Utah, United States. 140 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 January 2003 at 07:45

Classification

Incident

Location

Salt Lake City, Utah, United States

Coordinates

40.7883, -111.9928

Aircraft

Boeing 757-222

Registration

N551UA

Category

Airplane

Engines

2

Operator

United Airlines

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

San Francisco → Boston

Aircraft damage

Minor

Weather

VMC

Light

Night/Dark

NTSB number

DEN03IA033

Nobody was injured.

the arcing wires in the lavatory sensor that resulted in the subsequent fire.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The passenger jet was at a cruise altitude of 37,000 feet msl and approximately 95 nautical miles south of Salt Lake City (SLC), when a flight attendant called from the aft cabin and stated there was a fire in the left aft lavatory, and that another flight attendant was fighting the active flames with a Halon extinguisher. The captain declared an emergency, requested priority handling for landing at SLC, and made an uneventful landing. An examination of the airplane revealed the lavatory toilet water level sensor was charred and melted. On further examination, the top left corner of the circuit board in the sensor was melted and consumed. Portions of several wires that had solder attachments to the circuit board at the melted area, including a 115-volt AC input wire and a 28-volt DC ground wire were melted and consumed. The left side of the circuit relay, adjacent to the consumed area of the circuit board, was melted and had melted solder on its exterior. The left hexagon-shaped screw, one of the two screws that mount the relay to the circuit board, was also melted. The manufacturer determined the melting point of the screw was between 2,550 and 2,650 degrees F. The investigation team determined that for these temperatures to occur, one of the wires in the area of the left screw would have had to arc.

Quoted verbatim from the NTSB record.