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In September 2007, two separate incidents of similar landing gear failures occurred within four days of each other on Bombardier Dash 8-Q400 aircraft, all operated by Scandinavian Airlines (SAS). A third incident, again with an SAS aircraft, occurred in October 2007, leading to the withdrawal of the type from the airline's fleet.
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Scandinavian Airlines Flight 1209, a de Havilland Canada Dash-8-400 (LN-RDK), took off from Copenhagen Airport, Denmark, on September 9, 2007. It was headed to Aalborg Airport, Denmark. SK1209 is a code-shared flight with Spanair flight JK9101, BMI flight BD3923 and Lufthansa flight LH6002.
Prior to landing, the right main landing gear failed to lock and the crew circled for an hour before attempting a prepared emergency landing. Upon touchdown, the right landing gear collapsed, the right wing touched ground, and a fire broke out. The fire went out before the aircraft came to rest and all passengers and crew were evacuated. Five people suffered minor injuries, some from propeller parts entering the cabin and others from the evacuation.
When the handle for lowering the landing gear was activated, the indicator showed two green and one red light. The red light indicated that the right main gear was not locked in position. The landing was aborted. Attempts at lowering the gear manually were also unsuccessful. Investigation into the cause of the failure to deploy revealed that the right main gear hydraulics actuator top eyebolt was separated from the actuator. A further analysis of the actuator showed corrosion on the inside leading to reduced mechanical strength of the actuator and eventual failure.[1]
On September 19, 2007, the prosecutor of Stockholm commenced a preliminary investigation regarding suspicion of creating danger to another person.[2]
Scandinavian Airlines System (SAS) has been accused of cutting corners for maintenance. As the Swedish Civil Aviation Authority 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 airline reportedly made 2,300 flights in which safety equipment was not up to standard, although the airline has denied this.[3]
Radio Sweden International reports that a security analyst for the Norwegian Civil Aviation Authority has sent a warning to other Scandinavian aviation bureaus concerning sub-standard SAS maintenance procedures, including one instance where an aircraft took off after the pilot reported a fuel leak. This warning, while just publicized, was apparently written before the recent spate of SAS accidents.[4]
Scandinavian Airlines Flight 2748, a de Havilland Canada Dash-8-400 (LN-RDS), took off from Copenhagen Airport, Denmark, on September 12, 2007. It was headed to Palanga, Lithuania, but was diverted to Vilnius Airport when landing gear problems were discovered before landing. Upon touchdown, the right landing gear collapsed. All passengers and crew were evacuated safely.[5] The local officials at the Vilnius International Airport noted that this was the most serious incident in recent years.[6]
On October 27, 2007, a Dash 8-400 (LN-RDI), SAS flight SK2867 from Bergen, Norway, with 40 passengers and 4 crew members was enroute to Copenhagen, Denmark, when problems with the main landing gear were discovered. After waiting about two hours in the air to burn fuel and troubleshoot, the pilots attempted a prepared emergency landing. The pilots were forced to land the aircraft with the right main landing gear up. The right engine was shut off for the landing, because in the previous landings the propeller had hit the ground and shards of it ripped into the fuselage. This was not on the emergency checklist, rather it was the pilots making a safety based decision. The aircraft stopped on the runway with the right wing touching the runway at 16.53 local time. It did not catch fire and the passengers and the crew were evacuated quickly. There were no serious injuries. 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 Dash 8-400 fleet due to similar landing gear issues. The entire fleet was grounded again following the incident.[7][8][9]
The preliminary Danish investigation determined this latest Q400 incident is unrelated to the airline's earlier corrosion problems, in this particular case caused by a misplaced O-ring found blocking the orifice in the restrictor valve.[10][11] Accordingly EASA announced that "...the Scandinavian airworthiness authorities will reissue the Certificates of Airworthiness relevant to this aircraft type in the coming days."[11]
After the second incident, Scandinavian Airlines System (SAS) grounded their entire Dash-8-400 fleet consisting of 27 aircraft, and a few hours later the manufacturer Bombardier Aerospace recommended that all the Dash-8-400 aircraft with more than 10,000 flights stay grounded until further notice,[12] affecting about 60 of the 160 Q400 aircraft used worldwide. As a result, several hundred flights were cancelled around the world. Horizon Airlines grounded 19 of their aircraft and Austrian Airlines grounded eight.[13]
On September 13, 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 system and main landing gear retract actuator jam nut. This effectively grounded all Q400 aircraft until the inspection had been carried out.[14][15][16]
On September 14, 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. Bombardier acknowledged the likelihood of corrosion developing inside the retract actuator.[16]
Previous maintenance procedures mandated checking this component after 15,000 landings. The new maintenance schedule affects about 85 of the 165 Q400 aircraft worldwide. Some operators have found that spare parts for this unexpected actuator replacement program are not available, grounding their aircraft indefinitely.[17]
Skandinavisk Tilsynskontor investigators detected corrosion inside the actuator on 25 of 27 aircraft they checked. Accordingly, SAS decided to continue the grounding of its Dash-8-400 fleet until all the affected parts have been replaced.[18]
On October 28, 2007, SAS announced that it will remove all Dash-8-Q400 aircraft from service permanently.[19]
On March 10, 2008, a multi-party agreement was announced, attempting to finalize the roles of maintenance and manufacture in causing the SAS incidents; as settlement the airline and its partners ordered a replacement set of short-haul planes from Bombardier, and in turn received a US $164 million discount.[20]
It has been speculated that a November 2007 shakeup of Bombardier management has been spurred by the Dash-8-Q400 issues.[21]