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30th of September 2015, Blog #553

The crew of a Bombardier Inc. DHC-8-402 reported for duty for a series of four flights at ~05.30 lt (local time). After a series of uneventful flights, the crew was getting ready for the final sector of their flying day, from Saarbrücken-Ensheim Airport (Germany) to Luxembourg-Findel Airport (Luxembourg). when the 16 passengers were on board the aircraft start-up clearance was issued at 10.09 lt. With the engines started the aircraft headed towards the take-off runway, runway 09. During the taxi to the runway, the take-off clearance was issued 10.15 lt.

The aircraft shortly after the accident (Source: baaa-acro.com © unknown)


The Captain was the pilot flying (PF) while the co-pilot was the pilot monitoring (PM). At 10.16lt the take was initiated the standard callouts were made, additionally, non-essential remarks were made regarding the weather. As the take off continued the PM called out "V1, Rotate" when the speed wat ~127 knots, the pilot flying rotated the aircraft and when the aircraft reached a nose-up attitude of approximately 5º the landing gear retracted, two seconds had elapsed since the "V1, Rotate" call.


The tailstrike warning light illuminated at the moment the aircraft settled on the ground. The aircraft bounced three times and ~807 metres after the initial ground contact the aircraft came to a stop on the take-off runway, close to the runway centreline. Both the main landing gears were retracted with the landing gear doors closed. The nose landing gear was also retracted, and the nose landing gear doors were still open. As the aircraft came to a stop smoke and fumes developed in the cabin, and an evacuation was initiated. All passengers and crew were uninjured. There was no fuel leak and there was no post-accident fire.

The Bundesstelle für Flugunfalluntersuchung (BFU - German Federal Bureau of Aircraft Accident Investigation) was alerted and an investigation was initiated.

Damage to the aircraft was substantial;

  • Left propellor blades shortened by ~40 cm

  • Right propellor blades shortened by ~1 cm

  • Left lateral fin abraded by ~3cm

  • Lower fuselage skin scratched, dented and abraded from ~2m aft of the nose landing gear until the aft baggage compartment

The damaged lower fuselage skin and structure (© BFU)


During the investigation, several tests were carried out and it was determined that the landing gear will retract if the nose landing gear is airborne (Weight-on-Wheel switches -> air) but the main landing gears are still on the ground (WOW switches -> ground). The manufacturer stated that this corresponded with the design logic.


After an extensive investigation, the BFU published their investigation report on the 31st of October 2016. The investigation also determined that the landing gear retracts in accordance with the control design logic if the cockpit commands it (lever in position UP) and at least one landing gear (nose wheel or main landing gear) is airborne according to the weight on wheels sensors. During rotation with a lifted nose, this is the case. They concluded that the air accident was the result of an early retraction of the retractable landing gear during take-off, which was not prevented by the landing gear selector lever and the retracting control logic.

The landing gear lever, in a yellow circle (Source: V2 Aviation) The following contributory factors were also listed in the report;

  • Reduced concentration level

  • A break in the callout process/task sequence on the part of the PNF

  • Actuation of the landing gear lever to the UP Position too early

  • Control logic design allows retraction of the landing gear with one wheel airborne.

The full BFU investigation, on which this blog is based, can be accessed by clicking on the .pdf file below;

Dash 8 gear retraction on ground 30-sep-2015
.pdf
Download PDF • 2.11MB

Click on the button below to go to a video, in German, of the aftermath of the accident;





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