Date:	Tuesday 4 October 2016
Time:	05:50
Type:	Boeing 737-4Q8 (SF)
Owner/operator:	ASL Airlines Belgium
Registration:	OE-IAG
MSN:	25168/2210
Year of manufacture:	1992
Engine model:	CFMI CFM56-3C1
Fatalities:	Fatalities: 0 / Occupants: 2
Aircraft damage:	Minor, repaired
Category:	Accident
Location:	Belfast International Airport (BFS) -   United Kingdom
Phase:	Landing
Nature:	Cargo
Departure airport:	East Midlands Airport (EMA/EGNX)
Destination airport:	Belfast International Airport (BFS/EGAA)
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The aircraft had taken off from East Midlands Airport, United Kingdom carrying 16 tonnes of cargo. Destination was Belfast International Airport, Northern Ireland.
As the aircraft descended through 1,000 ft in preparation for landing on runway 25 at Belfast International Airport, it was configured with flaps 30, and autopilot and auto throttle were disengaged. The calibrated airspeed was about 148 kt (VREF + 7), with a tailwind component of approximately 5 kt and crosswind component of approximately 10 kt from the left.
As the aircraft descended below 500 ft, the descent rate was a nominal 800 fpm. This was maintained until about 40 ft agl when the landing flare was initiated, reducing to about 600 fpm (10 fps) at touchdown. The aircraft touched down with 1.7° of left bank and a drift angle of 3° to the right, at about 148 kt CAS (VREF + 7) and a peak recorded normal acceleration of 1.65 g.
The aircraft touched down about 250 m beyond the threshold of runway 25. The speedbrakes were deployed, and subsequently the thrust reversers and the brakes were selected. The crew felt a vibration that started to increase in intensity and they suspected a tyre failure. The anti-skid fail warning illuminated, and the crew cancelled the thrust reversers and automatic braking as sufficient runway remained in which to stop. The aircraft track continued to oscillate close to the runway centreline before stopping 2,170 m beyond the threshold of runway 25 at its intersection with runway 17/35. There were no injuries and the aircraft was moved from the runway at approximately 19:00 hrs.

The physical and recorded evidence indicate that the fracture to the lower torsion link on the right main landing gear leg was most likely caused by shimmy. This and previous occurrences show that the Boeing 737 main landing gear is susceptible to shimmy, particularly at higher landing speeds and for softer landings.
The manufacturer has a mature and well-documented list of probable causal factors for shimmy on this aircraft type. There was no evidence of a pre-existing defect in the failed torsion link or the apex joint which would have caused the shimmy. It was not possible to assess the condition of the shimmy damper or determine if there was any freeplay in the joints associated with the torsion links. Accordingly it is possible that there was a failure of the damper or excessive freeplay in the joints, which combined with the high-speed landing may have induced shimmy.

03:50 UTC / 04:50 local time:
EGAA 040350Z 14011KT 9999 FEW045 12/09 Q1026

04:20 UTC / 05:20 local time:
EGAA 040420Z 13011KT 090V150 CAVOK 12/09 Q1026

04:50 UTC / 05:50 local time:
EGAA 040450Z 13009KT CAVOK 12/09 Q1027

05:50 UTC / 06:50 local time:
EGAA 040550Z 13009KT 090V150 9999 FEW010 12/09 Q1027

Other occurrences involving this aircraft

6 April 2012	VP-BTA	Globus (S7 - Siberian Airlines) (Rostov-East)	0	Rostov-on-Don Platov International Airport (ROV/URRP)		min
Runway excursion
17 January 2013	VP-BTA	Globus	0	Moskva-Domodedovo Airport (DME/UUDD)		min
Taxiway excursion

photo (c) AAIB; Belfast International Airport (BFS); 04 October 2016

photo (c) AAIB; Belfast International Airport (BFS); 04 October 2016

photo (c) AAIB; 04 October 2016

Date/time	Contributor	Updates