# NTSB BFO92IA145: Lockheed L1011-385, N786DL, Boston, MA, September 20, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: September 20, 1992, 19:53 local (23:53 UTC)
- Place: Boston, MA
- Location: 42.3584° N, 71.0598° W: Placed by OpenAirDocs: center of Boston, MA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=42.3584&lon=-71.0598&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 315 uninjured
- Status: Completed, report June 30, 1993
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 11743
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=BFO92IA145
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/11743/pdf
- Page: https://openairdocs.org/ntsb/BFO92IA145

## Probable cause

INADEQUATE LUBRICATION WHICH CAUSED STRESS CORROSION CRACKING AND THE SEPARATION OF THE RIGHT WING NUMBER TWO FLAP VANE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach
  - flight control,flap attachment - stress corrosion (contributing factor)
  - maintenance,lubrication - inadequate, company maintenance personnel (cause)
  - flight control,flap attachment - separation (contributing factor)

## Analysis

THE PILOT WAS LANDING ON RUNWAY 4R, WHEN ACCORDING TO THE PILOT, HE WAS ESTABLISHED ON THE GLIDE SLOPE WHEN HE FELT A VIBRATION.  HE REPORTED THAT THE FLYING CHARACTERISTICS DEGRADED AND HE MADE THE NECESSARY CORRECTION SUCCESSFULLY. THERE WERE NO INDICATIONS IN THE COCKPIT OF ANY FAILURE. THE AIRPLANE TOUCHED DOWN 2 MINUTES LATER AND TAXIED TO THE GATE WITHOUT ANY FURTHER INCIDENCE.  INSPECTION OF THE AIRPLANE REVEALED SEPARATION OF THE NO. 2 FLAP VANE FROM THE RIGHT WING.  FURTHER TESTING BY THE NTSB LAB REVEALED THE SEPARATION OCCURRED DUE TO STRESS CORROSION AND FATIGUE CRACKING THAT INITIATED AT THE LUG BORE.

## Aircraft

- Registration: [N786DL](https://openairdocs.org/deregistered/N786DL-2012-09-10), registration cancelled 2012-09-10, S/N 193A-1123, built 1975 (OpenAirDocs)
- Reported make and model: LOCKHEED L1011-385
- Registry model: [Lockheed L-1011-385-1](https://openairdocs.org/model/lockheed-l-1011-385-1) (registry code 5265010) (OpenAirDocs)
- Registry engine: [Rolls-Royce RB-211-22 series](https://openairdocs.org/engine/rolls-royce-rb-211-22-series) (registry code 54554, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 193A-1123
- Airframe hours: 39472
- Engines: Rolls-Royce RB211 turbo jet
- Damage: Minor damage
- Flight: Part 121
- Operator: Delta Airlines
- Registered owner: Delta Airlines
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, September 12, 1992, 69 hours before
- Departed: ATL, ATLANTA, GA
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: unknown, unknown; seat: left; flight hours: 26,000 total

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 140° at 8 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 57 °F, dew point 50 °F
- Altimeter: 30.00 inHg
- Observed at: BOS, 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 19920920044949I](https://openairdocs.org/incident/19920920044949I), Sep 20, 1992: Lkheed 10113851, Boston, MA, Minor damage. Outboard fore flap on right inboard flap assembly broke loose and fell from aircraft on final approach.

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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