# NTSB DEN92IA025: Boeing 737-300, N343UA, Denver, CO, January 3, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: January 3, 1992, 13:55 local (20:55 UTC)
- Place: Denver, CO
- Coordinates: 39.760795, -104.919982 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.7608&lon=-104.9200&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 127 uninjured
- Status: Completed, report December 16, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18168
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN92IA025
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18168/pdf
- Page: https://openairdocs.org/ntsb/DEN92IA025

## Probable cause

AN ELECTRICAL SHORT CIRCUIT IN A MAIN WIRE BUNDLE DUE TO CHAFING OF THE BUNDLE ON AIRFRAME STRUCTURAL MEMBERS.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Fire, climb - to cruise
  - electrical system,electric wiring - chafed (cause)
  - electrical system,electric wiring - shorted (cause)
  - electrical system,electric wiring - fire (cause)

## Analysis

DURING CLIMB, THE CREW NOTED AN ELECTRICAL ARCING SOUND AND SLIGHT ELECTRICAL-TYPE BURNING ODOR WHILE PASSING THROUGH FLIGHT LEVEL 180. EMERGENCY PROCEDURES WERE COMPLIED WITH AND THE PROBLEM APPEARED TO BE SOLVED. THE CLIMB WAS CONTINUED, AND WHILE PASSING THROUGH FLIGHT LEVEL 330 A LOUD ARCING SOUND WAS AGAIN HEARD ACCOMPANIED BY FLAMES FROM THE FLIGHT DECK AFT OVERHEAD PANEL. THE FLIGHT ATTENDANTS EXTINGUISHED THE FIRE, AND THE FLIGHT RETURNED TO DENVER AND LANDED WITHOUT FURTHER INCIDENT. EXAMINATION DISCLOSED A SHORT IN A WIRE BUNDLE. THE BUNDLE WAS NOT SHIELDED OR ANCHORED AS THE OTHER MAJOR BUNDLE IN THE COMPARTMENT. THE SHORT WAS DUE TO THE BUNDLE CHAFING ON THE FLIGHT DECK ENTRY DOOR FRAME. IN ADDITION, TESTING REVEALED THAT THE WIRE GAUGE USED IN PART OF THIS APPLICATION WAS INSUFFICIENT FOR THE ELECTRICAL LOAD.

## Aircraft

- Registration: N343UA (not matched to a registry record)
- Reported make and model: BOEING 737-300
- Category: Airplane
- Serial number: 24247
- Airframe hours: 6974
- Engines: GE CFM 56 20000 lbs thrust turbo fan
- Damage: Minor damage
- Fire: In-Flight
- Flight: Part 121
- Operator: United Airlines
- Registered owner: United Airlines
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, March 5, 1991, 2,731 hours before
- Destination: LAS, LAS VEGAS, NV
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; airline transport; airplane ratings: multi-engine sea, single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 6,673 total, 1,399 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 7 knots
- Visibility: 99 statute miles
- Lowest ceiling: none
- Temperature: 48 °F, dew point 25 °F
- Altimeter: 29.00 inHg

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 19920103002519I](https://openairdocs.org/incident/19920103002519I), Jan 3, 1992: Boeing 737322, Denver, CO, Minor damage. Flight experienced electrical fire in galley. Wires shorted because of lack of clearance in ceiling panels.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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