# NTSB DEN89IA124: Boeing 727-247, N296WA, Denver, CO, May 24, 1989

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: May 24, 1989, 08:05 local (14:05 UTC)
- Place: Denver, CO
- Coordinates: 39.759796, -104.920349 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.7598&lon=-104.9203&mi=10
- Phase of flight: [Pushback/towing](https://openairdocs.org/ntsb-phases/200) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 121 uninjured
- Status: Completed, report August 26, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 17619
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89IA124
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17619/pdf
- Page: https://openairdocs.org/ntsb/DEN89IA124

## Probable cause

FAILURE OF THE LEFT MAIN LANDING GEAR FORWARD TRUNNION BEARING SUPPORT FITTING DUE TO A CRACK INITIATING AT THE FORWARD EDGE OF THE BORE AND PROPAGATING BY INTERGRANULAR STRESS CORROSION INTO THE BORE SURFACE THAT RESULTED IN AN EVENTUAL DUCTILE FRACTURE.

## Sequence of events

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

- Main gear collapsed, taxi - pushback/tow
  - landing gear,main gear attachment - failure,total (cause)
  - landing gear,main gear attachment - fractured (cause)
  - landing gear,main gear attachment - stress corrosion (cause)

## Analysis

THE LEFT MAIN LANDING GEAR COLLAPSED AS THE AIRCRAFT WAS PULLED FORWARD SLIGHTLY TO BRING THE NOSEWHEEL OFF THE CHOCKS PRIOR TO PUSHBACK. INSPECTION DISCLOSED A FRACTURE OF THE FORWARD TRUNNION BEARING SUPPORT FITTING (P/N 65-16206-11) AND HEAVY SURFACE CORROSION. MICROSCOPIC EXAMINATION DISCLOSED EXTENSIVE INTERGRANULAR STRESS CORROSION, AND A CRACK THAT HAD DEVELOPED 0.1 INCHES INBOARD FROM THE FORWARD EDGE OF THE BORE, WHICH HAD PROPAGATED APPROXIMATELY 2.1 INCHES AFT INTO THE BORE SURFACE. THE FINAL FRACTURE RESULTED FROM DUCTILE SEPARATION.

## Aircraft

- Registration: [N296WA](https://openairdocs.org/deregistered/N296WA-2006-11-08), registration cancelled 2006-11-08, S/N 22533, built 1981 (OpenAirDocs)
- Reported make and model: BOEING 727-247
- Registry model: [Boeing 727-247](https://openairdocs.org/model/boeing-727-247) (registry code 138408F) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D-15](https://openairdocs.org/engine/pratt-whitney-jt8d-15) (registry code 52051, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 22533
- Airframe hours: 25391
- Engines: P&W JT8D-15 15000 lbs thrust turbo fan
- Damage: Minor damage
- Flight: Part 121
- Operator: Delta Air Lines
- Registered owner: First Security Bank Of Utah
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, April 27, 1989, 217 hours before
- Departed: DEN
- Destination: ATL, ATLANTA, GA
- Flight plan: IFR
- Airport: KDEN, Stapelton Int'L

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; airline transport, flight engineer, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 8,200 total, 3,000 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 8 knots
- Visibility: 60 statute miles
- Lowest ceiling: none
- Temperature: 68 °F, dew point 30 °F
- Altimeter: 29.00 inHg
- Observed at: DEN

## 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 19890524012749I](https://openairdocs.org/incident/19890524012749I), May 24, 1989: Boeing 727247, Denver, CO, Minor damage. When aircraft pulled forward to remove nose chock 2 pins broke allowing left gear to collapse.

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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