Incident Overview

Date: Saturday 14 May 1977
Aircraft Type: Boeing 707-321C
Owner/operator: IAS Cargo, lsf Dan-Air Services
Registration Number: G-BEBP
Location: 3,7 km W of Lusaka Airport (LUN) – ÿ Zambia
Phase of Flight: Approach
Status: Destroyed, written off
Casualties: Fatalities: 6 / Occupants: 6
Component Affected: Right-hand horizontal stabilizer and elevator assemblyRight-hand horizontal stabilizer and elevator assembly
Investigating Agency: AIBAIB
Category: Accident
A Boeing 707 G-BEBP experienced a catastrophic loss of control during a cargo flight from Nairobi to Lusaka. The aircraft rapidly separated its right-hand stabilizer and elevator, resulting in a rapid nose-down dive and subsequent impact with the ground. The incident was caused by a combination of metal fatigue and inadequate failsafe design.A Boeing 707 G-BEBP experienced a catastrophic loss of control during a cargo flight from Nairobi to Lusaka. The aircraft rapidly separated its right-hand stabilizer and elevator, resulting in a rapid nose-down dive and subsequent impact with the ground. The incident was caused by a combination of metal fatigue and inadequate failsafe design.

Description

The aircraft departed Nairobi (NBO) at 07:17 for the final leg of a London-Heathrow – Athens – Nairobi – Lusaka cargo flight. Boeing 707 G-BEBP proceeded to Lusaka at FL310. At 09:07 the flight was cleared to descend to FL110. This altitude was reached at 09:23, 37nm DME from Lusaka. A clearance was then given to descend further down to FL70 in 1000 feet steps. At 09:28 the co-pilot reported that the airfield was in sight. Lusaka then cleared the aircraft to descend to 6000 feet (2221 feet above runway elevation) and moments later a clearance was given to make a visual approach for runway 10. At 09:32 flaps were selected to 50 degrees. Suddenly, at 09:33, the complete right-hand horizontal stabilizer and elevator assembly were seen to separate in flight. The aircraft pitched rapidly nose down and dived vertically into the ground from a height of about 800 feet. The main wreckage was located 3660 m from the runway threshold. CAUSE: “The accident was caused by a loss of pitch control following the in-flight separation of the right hand horizontal stabilizer and elevator as a result of a combination of metal fatigue and inadequate failsafe design in the rear spar structure. Shortcomings in design assessment, certification and inspection procedures were contributory factors.

Primary Cause

Metal fatigue and inadequate failsafe design in the rear spar structure.Metal fatigue and inadequate failsafe design in the rear spar structure.

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