Accident Boeing 737-4L7 ZS-OAA,

ASN Wikibase Occurrence # 320197

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Date:	Monday 26 October 2015
Time:	12:06
Type:	Boeing 737-4L7
Owner/operator:	British Airways
Registration:	ZS-OAA
MSN:	26960/2483
Year of manufacture:	1993
Total airframe hrs:	57543 hours
Engine model:	CFMI CFM56-3C1
Fatalities:	Fatalities: 0 / Occupants: 100
Aircraft damage:	Substantial, written off
Category:	Accident
Location:	Johannesburg-O.R. Tambo International Airport (JNB) - South Africa
Phase:	Landing
Nature:	Passenger - Scheduled
Departure airport:	Port Elizabeth Airport (PLZ/FAPE)
Destination airport:	Johannesburg-O.R. Tambo International Airport (JNB/FAOR)
Investigating agency:	CAA S.A.
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
A Boeing 737-400, operated by Comair on behalf of British Airways, sustained severe damage in a landing accident at Johannesburg-OR Tambo Airport, South Africa. There were 94 passengers and six crew members on board.
The aircraft, flight number BA6234, departed Port Elizabeth Airport at 08:20 UTC on an instrument flight plan rule for Johannesburg.
The first officer was the flying pilot for this leg. During approach to Johannesburg the aircraft was cleared for landing on runway 03R. The approach was flown with a tailwind (340° at 10 knots).
After crossing the runway threshold, the first officer began flaring the aircraft at 65 feet instead of 20 feet as recommended by Boeing. This contributed to a low sink rate (1.8 feet/second). The aircraft touched down at an excessive ground speed of 167 knots. The flight crew felt the aircraft vibrating, during which they applied brakes and deployed the reverse thrust.
The left main gear collapsed approximately 5 seconds after touchdown, causing the aircraft to roll slightly low to the left.
It later came to full stop around 35 seconds later, slightly left of the runway centreline, resting on its right main landing gear and the number one engine, with the nose landing gear in the air.
The aircraft sustained substantial damage as the number one engine scraped along the runway surface when the landing gear detached from the fuselage. The occupants were allowed to disembark from the aircraft via the left aft door due to the attitude in which the aircraft came to rest.
It was determined that the early flare and low sink rate on touchdown caused a condition in which excessive vibrations build up on the left landing gear and resulted in the upper torsion link failure.
The thermal relief valve of the shimmy damper contained oil which could have impaired its effectiveness
Significant wear was found on the upper torsion link bushes, which could have contributed with the un-dampened vibration build up during operation.

Probable Cause:
Unstable approach whereby the aircraft was flared too high with high forward speed resulting with a low sink rate in which during touch down the left landing gear experienced excessive vibration and failed due to shimmy events.

METAR:

09:00 UTC / 10:00 local time:
FAOR 260900Z VRB07KT CAVOK 26/05 Q1029 NOSIG

10:00 UTC / 12:00 local time:
FAOR 261000Z VRB05KT 9999 FEW045 26/04 Q1029 NOSIG

11:00 UTC / 13:00 local time:
FAOR 261100Z 12006KT 060V170 CAVOK 27/04 Q1028 NOSIG

Accident investigation:


Investigating agency:	CAA S.A.
Report number:	CA18/2/3/9494
Status:	Investigation completed
Duration:	1 year and 4 months
Download report:	Final report

Sources:

Location

Images:

photo (c) Tony Chica / ACSA; Johannesburg-O.R. Tambo International Airport (JNB); 26 October 2015

photo (c) AAIB; 26 October 2015

photo (c) Bart van Loon; Victoria Falls Airport (VFA/FVFA); 09 July 2015

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