# NTSB CHI91IA078: Boeing 727-251, N295US, St. Paul, MN, January 21, 1991

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: January 20, 1991, 20:45 local (Jan 21, 1991, 02:45 UTC)
- Place: St. Paul, MN
- Coordinates: 44.879962, -93.199829 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.8800&lon=-93.1998&mi=10
- Highest injury: No injuries
- Injuries: 44 uninjured
- Status: Completed, report September 28, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 14927
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91IA078
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14927/pdf
- Page: https://openairdocs.org/ntsb/CHI91IA078

## Probable cause

THE PARTIAL FAILURE OF THE AIRPLANE'S AUXILIARY POWER UNIT, AND THE INADEQUATE COMPONENT PRODUCED BY THE MANUFACTURER.

## Sequence of events

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

- Fire, taxi - to takeoff
  - auxiliary power unit - fire

## Analysis

THE FLIGHT CREW WAS INFORMED BY THE TOWER OF A FIRE ON THE RIGHT SIDE OF THE AIRPLANE WHILE TAXIING FOR TAKEOFF.  THE FIRE PRECEEDED BY UTILIZING THE AUXILARY POWER UNIT (APU) FOR A MAIN ENGINE START.  THE MAIN ENGINE START WAS ABORTED WHEN THE APU FAILED TO DELIVER SUFFICIENT BLEED AIR PRESSURE.  A POST INCIDENT INSPECTION OF THE APU DISCLOSED A LIBERATED TURBINE EXDUCER BLADE WHICH CAUSED AN IMBALANCE OF THE TURBINE WHEEL, ALLOWING SMOPKE AND FLAMES TO ESCAPE FROM THE APU EXHAUST ATOP THE RIGHT WING ROOT.  THERE HAS BEEN 7 SERVICE DIFFICULTY REPORTS AND 4 ACCIDENTS/INCIDENTS ASSOCIATED WITH EXDUCER FAILURES IN THIS MODEL APU IN THE LAST FIVE YEARS.

## Aircraft

- Registration: [N295US](https://openairdocs.org/deregistered/N295US-2004-06-01), registration cancelled 2004-06-01, S/N 21506, built 1978 (OpenAirDocs)
- Reported make and model: BOEING 727-251
- Registry model: [Boeing 727-251](https://openairdocs.org/model/boeing-727-251) (registry code 138408H) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D-5](https://openairdocs.org/engine/pratt-whitney-jt8d-5) (registry code 52046, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 21506
- Engines: P&W JT8D-15 15000 lbs thrust turbo fan
- Damage: Minor damage
- Fire: On-Ground
- Flight: Part 121
- Operator: Northwest Airlines, Inc.
- Registered owner: First Security Bank Of Utah
- Last inspection: Continuous airworthiness, January 2, 2000
- Destination: PHL, PHILADELPHIA, PA
- Flight plan: IFR
- Airport: MSP, Mineapolis St. Paul

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 37; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 750 total, 750 in this make and model

## Weather

- Conditions: Visual (VMC), Night/bright
- Wind: 340° at 12 knots
- Visibility: 12 statute miles
- Lowest ceiling: none
- Temperature: 9 °F
- Observed at: MSP, 1 nm away

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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