# NTSB FTW92IA055: Boeing 737-232, N322DL, Dfw Airport, TX, January 7, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: January 7, 1992, 13:32 local (19:32 UTC)
- Place: Dfw Airport, TX
- Location: 32.8972° N, 97.0377° W: Placed by OpenAirDocs at DALLAS-FORT WORTH INTL (DFW), within about a mile (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=32.8972&lon=-97.0377&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 49 uninjured
- Status: Completed, report June 30, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18386
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW92IA055
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18386/pdf
- Page: https://openairdocs.org/ntsb/FTW92IA055

## Probable cause

THE FAILURE OF THE AFT CONE BOLT AS RESULT OF PREEXISTING FATIGUE CRACKING DUE TO IMPROPER MAINTENANCE, AND THE FAILURE OF THE SECONDARY SUPPORT STRUCTURE AS A RESULT OF LOADS THAT EXCEEDED THE CAPACITY OF THE ATTACHING HARDWARE AND THE   CRUSHABLE HONEYCOMB CORE.

## Sequence of events

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

- Engine tearaway, takeoff - initial climb
  - engine installation,mounting bolt - fatigue (cause)
  - installation - improper, company maintenance personnel (cause)
  - engine installation,mounting bolt - failure,total (cause)
  - engine installation,suspension mounts - disconnected (cause)
  - powerplant - separation
  - engine installation,suspension mounts - overload

## Analysis

THE RIGHT ENGINE SEPARATED FROM THE WING AS THE AIRPLANE WAS CLIMBING THROUGH 200 FEET AFTER TAKEOFF. FOLLOWING THE ENGINE SEPARATION, THE CREW CONTINUED THE CLIMB AND WERE VECTORED FOR AN UNEVENTFUL LANDING WITHOUT FURTHER INCIDENT. ENGINE SEPARATION WAS THE RESULT OF THE FAILURE OF THE AFT CONE BOLT AND THE ENGINE SECONDARY SUPPORT ASSEMBLY. THE AFT CONE BOLT FAILED AS RESULT OF A PREEXISTING FATIGUE CRACK, WHILE THE ENGINE SECONDARY SUPPORT ASSEMBLY FAILED AS RESULT OF THE DYNAMIC LOADS THAT EXCEEDED THE DESIGNED CAPACITY OF THE MOUNTING BOLTS. THE TWO FORWARD CONE BOLTS FAILED IN OVERLOAD AS THE ENGINE SWUNG FORWARD DURING THE SEPARATION SEQUENCE. METALLURGICAL TESTING REVEALED THAT THE FATIGUE OF THE AFT CONE BOLT WAS A RESULT OF LUBRICANT INADVERTENTLY INTRODUCED INTO THE CONICAL SURFACE OF THE CONE BOLT.

## Aircraft

- Registration: [N322DL](https://openairdocs.org/deregistered/N322DL-2021-01-09), registration cancelled 2021-01-09, S/N 23094, built 1984 (OpenAirDocs)
- Reported make and model: BOEING 737-232
- Registry model: [Boeing 737-232](https://openairdocs.org/model/boeing-737-232) (registry code 1384475) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D series](https://openairdocs.org/engine/pratt-whitney-jt8d-series) (registry code 52053, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 23094
- Airframe hours: 20468
- Engines: P&W JT-8D-15 15500 lbs thrust turbo fan
- Damage: Minor damage
- Flight: Part 121
- Operator: Delta Air Lines, Inc.
- Registered owner: Delta Air Lines, Inc.
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, December 23, 1991, 82 hours before
- Departed: DFW
- Destination: IAH, HOUSTON, TX
- Flight plan: IFR
- Airport: DFW, Dfw Airport, runway 18, 11,387 × 200 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 49; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 12,000 total, 8,200 as pilot in command, 209 in the last 90 days, 55 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 8 knots
- Visibility: 15 statute miles
- Lowest ceiling: 7,500 ft overcast
- Temperature: 61 °F, dew point 48 °F
- Altimeter: 29.00 inHg
- Observed at: DFW, 1 nm away

## 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 19920107000289I](https://openairdocs.org/incident/19920107000289I), Jan 7, 1992: Boeing 737232, Dallas-Ft Worth, TX, Minor damage. NR2 lengine separated from aircraft after departure. Aircraft returned and landed without incident.

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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