SAR Seat Slip Smash (RCAF CH149 Leonardo Cormorant LOC-I)
The Royal Canadian Air Force (RCAF) is investigating a Loss of Control – Inflight (LOC-I) accident that occurred to Search and Rescue (SAR) Leonardo CH149 Cormorant (AW101) CH149903 at Gander, NL on 10 March 2022.
The SAR helicopter, callsign Outcast 903, of 103 Search and Rescue Squadron, 9 Wing was completing an onshore rear crew focused training flight, the first of two planned for the day at c15:42 Local Time. There were six crew members on board: two pilots, two Flight Engineers and two Search and Rescue Technicians.
At the end of the first training mission, the crew conducted hover work in the vicinity of the intersection of Runway 31 and Runway 21.
During the final clockwise hover turn sequence, the pilot flying’s seat unexpectedly descended to its lowest position.
The aircraft flight vector immediately reversed from a clockwise rotation to an accelerated counter clockwise left yaw about the aircraft mast. As the aircraft continued to yaw left, the attitude of the aircraft became unstable resulting in an increasing right bank attitude. The aircraft rotated through approximately 400° and as the right rolling moment intensified, the right outboard wheel, the horizontal stabilizer assembly located on the right side of the tail section, and main rotor blades impacted the runway.
Two of the crew received serious injuries, three minor injuries and one egressed uninjured.
The aircraft was significantly damaged on impact with the ground (although AW101s, aka Merlins, have been successfully rebuilt after major accidents [in one case an accident in Afghanistan, followed by being dropped by a US helicopter during the recovery and being dragged into a compound by armoured vehicle!]).
The RCAF report their safety investigation is focusing on “materiel and human factors“. We will update this article as they release more information.
UPDATE 29 July 2023: The conclusions of the investigation have been published:
The investigation determined that a combination of factors, including seat non conformances and the horizontal position that was maladjusted, allowed the seat to be in a false lock condition.
When the seat dropped, the loss of outside visual references in combination with the severe vertical vibration resulted in an unrecognized spatial disorientation of the pilot flying. This caused the pilot flying to incorrectly perceive a right yaw and apply full left pedal input; this led to a severe left yaw and contributed to the change in roll attitude that likely rendered the helicopter unrecoverable.
Multiple special inspections and aircrew information files were issued to address the seat non-conformances and avoid false lock conditions. Additional preventive measures have been identified to address deficiencies in fire fighting services, egress and tracking of armament as highlighted during this investigation.
The seat’s lock pins, which lock it in place, were shorter than manufacturing requirements… That could result in the pins not fully engaging with the locking mechanism…which could provide a false sense that the seat is locked.
The pins can’t be seen when the seat is installed “meaning there is no opportunity for visual confirmation by the pilot to know the seat is locked in place”.
The pilot checked whether the seat was locked before the flight by doing a “wiggle check,” according to the report, moving back and forth to make sure it was locked in place.
CBC say that investigators…
…also found that the seat’s dual lever control assembly was likely out of adjustment, which paired with the shorter-than-regulation lock pins could have led to the seat not being locked in, despite feeling locked in.
Seats locking problems were reportedly a “known issue” in the fleet and “discussed among crew members before the flight started”.
This accident is a good reminder to pay attention to the maintenance, adjustment and operation of pilot’s seats.
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