Thomas Cook B753 near London on Oct 31st 2014, dropped over wing slide

Last Update: August 14, 2015 / 20:03:41 GMT/Zulu time

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Photo of Thomas Cook Airlines G-JMAB, Boeing 757-300 — Thomas Cook Airlines G-JMAB, Boeing 757-300 (Photo credit: Hawkwindzoo - Steve Walsh / Flickr / License: CC by-nd)

Incident Facts

Date of incident
Oct 31, 2014

Classification
Incident

Airline
Thomas Cook Airlines

Flight number
MT-1638

Departure
London Gatwick, United Kingdom

Destination
Hurghada, Egypt

Aircraft Registration
G-JMAB

Aircraft Type
Boeing 757-300

ICAO Type Designator
B753

A Thomas Cook Boeing 757-300, registration G-JMAB performing flight MT-1638 from London Gatwick,EN (UK) to Hurghada (Egypt) with 237 people on board, had just reached cruise level 330 about 200nm east of Gatwick Airport and southsoutheast of Brussels (Belgium) when the crew received an abnormal indication and decided to burn off fuel and return to Gatwick Airport. On approach to the airport the aircraft dropped one of the over wing escape slides. The aircraft landed safely back in Gatwick about 2 hours after departure.

The airline reported the crew received indication of a fault with the over wing escape slide and decided to return to Gatwick. The slide separated from the aircraft somewhere along the flight.

Kent Police reported the object is believed to have fallen down between Langton Green and Groombridge, about 15nm east of Gatwick Airport, about 5 to 10 minutes prior to the aircraft landing back in Gatwick.

A passenger reported that shortly after the top of climb (aircraft levelled off after having reached cruise flight) the captain announced a technical fault requiring them to return to Gatwick. The aircraft burned off fuel for about 1.5 hours over the Gatwick and Brighton area. While on following approach to Gatwick Airport a very loud thump sound occurred and something believed to be a panel separated from the aircraft, probably hitting the fuselage and or tailplane. The aircraft touched down safely, stopped at the end of the runway and shut both engines down for an inspection by emergency services.

The AAIB have opened an investigation.

A replacement Boeing 767-300 registration G-POWD reached Hurghada with a delay of 7:45 hours.

On Aug 14th 2015 the AAIB released their final report concluding the probable cause of the serious incident was:

The right over-wing slide carrier deployed in flight, allowing the slide to unravel possibly as a result of the crank handle with a reduced breakout friction progressively moving, over an indeterminate period of time, to an unsafe position. A contributory factor was possibly the loose number 6 screw jack in the flap system which resulted in vibration in the area of the crank handle. The insecurity of the lever went undetected whilst the maintenance panel was open due to the lack of alignment marks and unfamiliarity of the observer(s) with how the crank handle should look when correctly positioned. SB 757‑25-0298 addresses locking of the compartment door and provides revised and clearer alignment placards for the lever.

The AAIB reported the crew received a "Wing Slide" EICAS indication while accelerating through 70 knots for takeoff, the captain (50, ATPL, 15,300 hours total, 8,765 hours on type) instructed the first officer to continue takeoff. There were no other abnormal indications or unusual handling of the aircraft. During the climb consulted with company, who decided the aircraft should return and burn off fuel rather than perform an overweight landing. The aircraft was on the base leg on approach to Gatwick at about 3000 feet, flaps were selected to 20 degrees, when some passengers and cabin crew heard some bangs and felt some aircraft shudder while two passengers saw a white object depart from the aircraft's right side, cabin crew informed the flight crew. The commander noticed that the control yoke was displaced 30 degrees to the left and the autopilot appeared to struggle to keep the wings level, the commander disengaged the autopilot and took manual control of the aircraft requiring a significant amount of left aileron to maintain wings level. The commander managed a safe landing 126 minutes after departure and stopped on the taxiway parallel to the runway, where it was discovered the right hand overwing slide had separated from the aircraft.

Examination showed that the slide had deployed in flight about one minute prior to separation.

The right hand crank handle was found in the up (release) position, the left hand crank handle was found in the down (closed) position. The slide gas bottle was found still charged.

The AAIB analysed: "Maintenance work was carried out on the slide gas bottle the night before the incident. Part of the preparatory procedure prior to carrying out the work was to make the gas pressure side of the actuation system safe by moving the vent lever to the open position. This was carried out in accordance with the AMM. Then, following the AMM instructions, the team of engineers changed the gas bottle and re-established the slide gas system into the service condition by closing the vent lever and securing its access panel. When carrying out this action the individual concerned did not recall touching or moving the crank handle. Furthermore he would not have needed to do so due to the position and design of the vent lever. None of the engineering staff involved at the time noticed anything unusual about the cranked handle or its position. However, with hindsight they were not completely sure that it was correctly positioned when later compared to diagrams in the AMM. The possibility that the lever was inadvertently knocked towards the release position cannot be discounted. However, had it been fully moved to the release position, the slide carrier panel would have opened slightly and been seen by the engineers. It would also have caused an immediate EICAS caution of r wing slide during pre‑flight checks. However, it is possible it had only been partially moved such that it remained closed but in a position that it would require an additional factor to cause its continued travel. It may therefore be concluded that the crank handle was not fully down in the safe position but was engaged enough to hold the panel and slide carrier in place. The absence of the alignment markings on the panel, designed to indicate if a crank lever is not correctly secured, would have reduced the possibility of its mis-position being identified by the engineers. SB 757‑25-0298 mandated under FAA AD 2012-01-09 introduces clearer crank handle position indication but it had not been incorporated on G-JMAB."