UK warning for Bombardier Challenger 600 series


The UK Aviation Accident Investigation Branch (AAIB) has issued a special bulletin for actions to take in the case of an uncommanded flap deployment in flight on the Bombardier Challenger 600 series.

The AAIB is calling on Bombardier to issue the recommendations to operators of the aircraft following an ongoing investigation of an incident this year.

On August 10th, after departing Farnborough Airport, a German-registered Challenger 604 experienced an uncommanded flat extension above the maximum flaps extended speed while the jet was climbing. The jet, which had three crewmembers and seven passengers onboard, returned to the airport and landed without incident.

The reason for the uncommanded extension of the flaps has not yet been determined, but testing identified that one of the two motor-retract relays was not working properly. This resulted in the flaps being retracted at half-speed as they were only being driven by one of the two motors. There is no warning system to indicate the flaps are operating on one motor at half speed, and on the D-AAAY registered aircraft the uncommanded flap movement protection system did not work. The initial findings showed the flaps on D-AAAY had been retracing at half-speed since at least a month before the incident.

The bulletin said that other aircraft in the fleet “may be operating with a similar latent failure” of flaps operating at half-speed that “could render the uncommanded flap movement protection system ineffective”.

AAIB said Bombardier needs to advise operators of the potential issue by October 20th. Transport Canada has advised the UK investigation branch that it will work with Bombardier to determine any appropriate actions to ensure the protection systems operate as intended.

A Bombardier spokesperson told Corporate Jet Investor: “Bombardier is working closely with the UK AAIB and the Transportation Safety Board of Canada [TSB] to investigate the cause of the event, and with Transport Canada to ensure the continued airworthiness of its Challenger 600-series aircraft.

“Bombardier will proactively and transparently keep its aircraft operators informed of any action required. All Challenger 600-series aircraft operations continue safely and reliably worldwide.”

The investigation by AAIB will continue to identify the cause of the problem and the four flap extend and retract relays and flap system components will be sent for more detailed examination and testing.

Read the full special bulletin here.  


Leave a Reply

Your email address will not be published. Required fields are marked *