El Magal AN12 at Heglig on Jan 4th 2010, gear collapse, runway excursion
Last Update: May 19, 2013 / 19:06:23 GMT/Zulu time
Incident Facts
Date of incident
Jan 4, 2010
Classification
Accident
Cause
Runway excursion
Aircraft Registration
ST-AQQ
Aircraft Type
Antonov An-12
ICAO Type Designator
AN12
- Landing short of the runway beginning.
- The flight engineer unlocked props I, II, III at throttle position Contributory Cause:
- Unrectification of nose wheel and main landing gear crack as recommended by the manufacturer.
The SAAICD reported the aircraft was performing flight Magal 100 from Khartoum to Heglig carrying 4 crew and 13 tons of cargo.
The captain (52, ATPL, 7,050 hours total, 6,000 hours on type) was assisted by a first officer (57, ATPL, 10,038 hours total, 7,050 hours on type), a flight engineer and a navigator.
The aircraft, Antonov AN-12 registration ST-AQQ MSN 9346504, had accumulated 36,190 hours since new and 35,986 hours since last check (editorial note, given the history of the airframe parked in Sharjah for years and being in an unairworthy condition as shown by pictorial evidence, the last check obviously occurred at 35,986 hours since new and the aircraft had operated 204 hours since). The operator El Magal Airlines had maintenance contracts with approved facilities in Khartoum (Sudan). El Magal had requested prolongation of the certificate of airworthiness in 2009 and had received instructions to implement further steps as requested by the design bureau, in January 2010 these works were completed and the prolongation of the airworthiness certificate was issued.
Following an uneventful flight at FL180 the aircraft positioned for an approach to runway 34 in good weather (winds from 020 degrees at 5 knots, CAVOK conditions, temperature 22 degrees C) but touched down about 16 meters ahead of the runway threshold with the main gear on gravel, the main landing gear contacted a number of concrete blocks holding the runway threshold lights, the nose gear touched down 40 meters past the threshold, the aircraft bounced and touched down a second time 52 meters past the threshold with the nose gear first. 183 meters past the threshold the inner right hand main tyre burst, 401 meters past the threshold first indications of braking appeared on the runway. The captain commanded the flight engineer to unlock the reversers, without checking the throttle positions the flight engineers brought the propellers into reverse. While thrust levers 1-3 were at idle, thrust lever 4 was not but at the 42 degrees position resulting in the propeller not going into beta range and continuing to deliver forward torque. The aircraft began to veer to the left about 409 meters past the threshold, the aircraft crossed the left runway edge, 506 meterrs past the threshold the aircraft began to veer back towards the runway centerline at a heading of 330 degrees (runway direction 325 degrees) but again turned left exiting the runway again about 729 meters past the threshold, crossed a gravel road 142 meters further down the runway resulting in the collapse of the left main gear, subsequently right hand and nose gear collapsed and the aircraft came to a stop at position N9.9962 E29.3972 facing west (270 degrees) 983 meters past the runway threshold.
Emergency services responded and prevented a fire by foaming the aircraft and watering the surrounding, emergency crews assisted the flight crew in opening the left main door and leaving the aircraft.
All occupants disembarked uninjured, the aircraft received substantial damage: left wing twisted forward, left wing tip bent upwards, all gear struts collapsed, cracks all around the aircraft, propeller #1 non-feathered, propellers 2-4 feathered, all propeller blade leading edges bent. Three runway threshold lights and the "bird strike transmitter" were damaged on the ground.
The aircraft was equipped with cockpit voice recorder and flight data recorder. The cockpit voice recorder was successfully read out and contained 18 flights but not the accident flight, there was evidence the magnetic tape mechanism had jammed prior to the accident flight. The flight data recorder was successfully read out, it turned out however that recordings occurred only with the spool turning in one direction while in the reverse direction there were no recordings whatsoever (unlike designed). There were no data of the accident flight present.
The SAAICD analysed that the aircraft veered left because of engines 1-3 going into beta and delivered backward torque while propeller #4, due to the engine thrust lever not in idle, continued to deliver forward torque. The captain, unaware of this fact and in panic because of the landing short of the runway and impact with the concrete blocks, did nothing. When the aircraft went over the gravel road the left main gear detached due to impact forces, the nose and right hand main gear subsequently collapsed as result of pre-existing cracks, that should have been fixed before flight (or the aircraft be grounded), those cracks existed even before the certificate of airworthiness was prolongated on Jan 15th 2010, neither cracks were noted in the technical logs of the aircraft.
The SAAICD therefore analysed that the airworthiness certificate prolongation had been issued without checking the airframe.
The SAAICD concluded the analysis that the accident could have been avoided, had the captain decided to go around at the latest after the second bounce.
The investigation released 4 safety recommendations to the operator, 3 safety recommendations to Sudan's Safety and Operations Directorate, 2 safety recommendations to Sudan's Airworthiness Directorate and one safety recommendation to Sudan's Civil Aviation Authority, all mainly concerning maintenance, airworthiness certification, qualification of personnel and oversight of these.
Incident Facts
Date of incident
Jan 4, 2010
Classification
Accident
Cause
Runway excursion
Aircraft Registration
ST-AQQ
Aircraft Type
Antonov An-12
ICAO Type Designator
AN12
This article is published under license from Avherald.com. © of text by Avherald.com.
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