Hydraulic fluid leak led to 2018 landing incident in Stephenville, Newfoundland and Labrador
Dartmouth, Nova Scotia, 20 July 2020 — In its investigation report (A18A0088) released today, the Transportation Safety Board of Canada (TSB) found that a hydraulic fluid leak on the aircraft’s nose landing gear shock strut caused the tires to become jammed. As a result, the commercial passenger flight landed in Stephenville, Newfoundland and Labrador, with the nose landing gear only partially extended.
On 15 November 2018, a Bombardier DHC-8-315 aircraft, operated by PAL Airlines Ltd. was conducting a flight between Churchill Falls and Deer Lake, Newfoundland and Labrador, with four crew members and 47 passengers on board. At 10:57 Newfoundland Standard Time, during the approach to Deer Lake Airport, the flight crew selected the landing gear down but the indicators showed that the nose landing gear was not in the down‑and‑locked position. As a result, the flight crew executed a missed approach and entered a hold in order to troubleshoot the problem. At 12:02, the crew requested a diversion to Stephenville and declared an emergency. At 12:30, the aircraft landed at Stephenville with the nose landing gear in a partially extended position. On touchdown, the nose landing gear fully collapsed, and the aircraft’s nose structure came into contact with the runway surface. The aircraft slid and came to a stop approximately halfway down the runway. All occupants on board exited the aircraft and no injuries were reported. The aircraft sustained minor damage. There was no post-impact fire.
The investigation determined that a repair to the inner cylinder of the nose landing gear shock strut made by a previous operator resulted in the installation of a standard size bearing where an oversize bearing was required. The reduced sealing force caused by the smaller bearing likely allowed the nose landing gear shock strut to leak. The reduced internal static pressure, combined with airflow encountered during landing gear extension, compressed the shock strut and allowed the tires to become jammed on the rear landing gear doors.
The investigation also found that the captain made a call to company dispatch using his smartphone. The ensuing troubleshooting discussion between the captain and PAL Airlines Ltd. management personnel lasted for more than 66 minutes, approximately until the aircraft touched down at Stephenville airport. Although having a third party provide input during an emergency can be helpful, an additional channel of communication for an extended period of time decreased the crew’s shared situational awareness during critical phases of flight and disrupted checklist flow and coordination normally required to effectively conduct checklists. Additionally, it was identified that the absence of formal in-flight procedures for flight crews to consult third parties using smartphones increases the risk of distraction, leading to a potential breakdown in crew resource management during critical phases of flight. In this occurrence, the time the crew spent continuing to try to lower the landing gear before deciding to divert caused them to use some of their reserve fuel. If pilots delay making a decision to divert, there is a risk that the fuel remaining may be insufficient to provide the flight endurance required to mitigate unforeseen circumstances at the diversion airport.
Following the occurrence, PAL Airlines Ltd. amended its company-designed Dash 8 layover check to include emphasis on the nose landing gear shock strut minimum and maximum extension measurements. The airline also updated its standard operating procedures to include a formal checklist of items to be inspected when pilots conduct the exterior inspection of the Dash 8 aircraft.
See the investigation page for more information.
The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
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Transportation Safety Board of Canada
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