In September 2007, two separate accidents due to similar landing gear failures occurred within three days of each other on Bombardier Dash 8 Q400 aircraft operated by Scandinavian Airlines System (SAS).
Scandinavian Airlines System Flight 1209, a Bombardier Dash 8 Q400 registered as LN-RDK, took off from Copenhagen Airport, Denmark, on 9 September 2007.
As the Swedish Civil Aviation Administration began an investigation of the accident, it brought renewed focus on SAS maintenance procedures.
(Only two weeks previously, Swedish authorities had levelled a scathing critique at the airline after an aircraft of the same model nearly crashed because its engine accelerated unexpectedly during landing.)
The outcome of the investigation was that the cause was not a lack of maintenance but over-cleaning of the landing gear, with pressure washers being used that washed out the corrosion preventative coatings between the eyebolt and the actuator rod end.
[4]A second accident occurred when a Bombardier Q400, operating as Scandinavian Airlines System Flight 2748, took off from Copenhagen Airport, Denmark, on 12 September 2007.
[citation needed] On 27 October 2007, a Q400 registered as LN-RDI was operating SAS Flight 2867 from Bergen, Norway to Copenhagen, Denmark with 40 passengers and 4 crew members when problems with the main landing gear were discovered.
The aircraft in question was one of six that had been cleared to fly just a month before, following the grounding of the entire Scandinavian Airlines Q400 fleet due to similar landing gear issues.
[7][8][9] The preliminary Danish investigation determined this latest Q400 accident was unrelated to the airline's earlier corrosion problems; in this particular case being caused by a misplaced o-ring found blocking the orifice in a hydraulic restrictor valve.
[13] On 13 September 2007, Transport Canada issued an Airworthiness Directive applicable to Bombardier Q400 turboprop aircraft instructing all Q400 aircraft operators to conduct a general visual inspection of the left and right main landing gear systems and main landing gear retract actuator jam nuts.
[14][15][16] On 14 September 2007, Bombardier issued an All-Operators Message (AOM) recommending new procedures concerning the landing gear inspection for all aircraft with more than 8,000 flights.
[18] On 28 October 2007, SAS announced that it would retire its entire fleet of Q400 aircraft after a third accident involving the landing gear occurred the day prior.
[19] On 10 March 2008, a multi-party agreement was announced, attempting to finalize the roles of maintenance and manufacture in causing the SAS accidents; as settlement the airline and its partners ordered a replacement set of short-haul aircraft from Bombardier, and in turn received a US$164 million discount.