Incident Overview

Date: Sunday 20 September 1992
Aircraft Type: Lockheed L-1011-385 TriStar
Owner/operator: Delta Air Lines
Registration Number: N786DL
Location: Boston-Logan International Airport, MA (BOS/KBOS) – ÿ United States of America
Phase of Flight: Approach
Status: Minor
Casualties: Fatalities: 0 / Occupants: 315
Component Affected: The No. 2 flap vane and the right wing.The No. 2 flap vane and the right wing.
Investigating Agency: NTSBNTSB
Category: Accident
The aircraft landed safely on Runway 4R, despite experiencing degradation in flight characteristics due to a vibration. The pilot successfully corrected the issues, and the aircraft landed 2 minutes later and taxied to the gate without further incident. An inspection revealed a separation between the No. 2 flap vane and the right wing, caused by stress corrosion and fatigue creasing.The aircraft landed safely on Runway 4R, despite experiencing degradation in flight characteristics due to a vibration. The pilot successfully corrected the issues, and the aircraft landed 2 minutes later and taxied to the gate without further incident. An inspection revealed a separation between the No. 2 flap vane and the right wing, caused by stress corrosion and fatigue creasing.

Description

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

Source of Information

https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001211X15610&key=1https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001211X15610&key=1

Primary Cause

Stress corrosion and fatigue creasing caused by inadequate lubrication.Stress corrosion and fatigue creasing caused by inadequate lubrication.

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