Narrative:On the day before the accident, the flight crew had completed 53 water-drop flights at a forest fire located northeast of Wabush, Newfoundland and Labrador. Each flight, typically about 3 minutes long, consisted of scooping water from Moosehead Lake, dropping the water on the fire, and then returning for another water scoop.
All flights were made with the PROBES AUTO/MANUAL switch in the AUTO selection. The switch was left in this position at the end of these flights.
At about 14:00 on the day of the accident, the flight crew were deployed to the same forest fire that they had been working on the day before. The captain was the pilot flying (PF) for the occurrence flight and occupied the left seat. The captain removed the centre pedestal cover during the pre-flight preparations. The first officer, who was the pilot not flying (PNF), completed the exterior walk-around and carried out the pre-flight cockpit checks.
The aircraft had 7000 pounds of fuel and 1000 pounds of chemical foam on board. Utilizing this information, the water-drop control computer determined the maximum quantity of water to be scooped.
The flight crew considered the wind speed and direction and decided to follow the same practice as the previous day and scoop water from Moosehead Lake.
After takeoff, the PNF was required to complete the "After Takeoff" checklist, and in preparation for scooping water, to complete the "Water Bombing in Range" and "Pick-up" checklists.
About 4 minutes after takeoff, the aircraft touched down about 1250 feet from the eastern shore of the lake, on a heading of 250°. The PF then applied takeoff power, and the PNF began adjusting the torque limit stops. Throughout the scooping run, the PNF was focused on ensuring that the soft stops were set as per the PF's instructions.
While adjusting the soft stops, the PNF noted that the water tanks were completely full, and advised the PF that the probes were still down and the PROBE AUTO/MANUAL switch was in the MANUAL selection. The PNF then manually selected the probes up. The probes retracted about 3490 feet after touchdown.
The flight crew continued the takeoff despite indication by the water status display panel that water quantity was in excess of that allowable for this takeoff.
At the time the probes were retracted, the aircraft was about 2500 feet from the departure-end shoreline of the lake. The PF determined that the aircraft would require a greater distance to become airborne and initiated a left turn to follow the lake. About 2 seconds later, the aircraft’s hull began to lift out of the water, and the left float contacted the water.
For the next 4 seconds, aileron and rudder control surface deflections commanded a left turn; however, during this time, the aircraft was skidding to the outside of the turn. The float remained in contact with the water, and the aircraft‘s hull was completely out of the water. The PF deflected the elevators up to near full deflection, with no corresponding response in pitch attitude, and then initiated a right turn using ailerons, with no response to this input.
About a second later, the aircraft’s hull was about 7 feet above the water, with the float still in contact with the water. The float separated from its pylon, resulting in a sudden pitch-down moment.
The forward section of the hull collided with the water, causing the lower part of the forward fuselage to tear open. The right wing float collided with the water, causing complete separation of the right float and pylon. The aircraft came to rest upright, with the cockpit partially underwater. The flight crew briefly delayed their evacuation until the propellers had stopped rotating.
The PNF retrieved a life vest and evacuated the aircraft through the overhead escape hatch. Once on top of the aircraft, the PNF donned the life vest. The PF could not retrieve a life vest and exited the aircraft through the left-side sliding window.
The flight crew remained on the wing as the aircraft continued to sink. The PNF contacted company personnel by cellular telephone and advised them of the situation. Within about 30 minutes, Department of Natural Resources employees arrived by boat and transported the flight crew to shore.
The aircraft settled on the lake bottom, about 225 feet from the southern shore of the lake.
Neither pilot attempted to remotely activate the emergency locator transmitter (ELT), shut down the engines or select electrical power OFF.
Probable Cause:Findings as to causes and contributing factors:
1. It is likely that the PROBES AUTO/MANUAL switch was inadvertently moved from the AUTO to the MANUAL selection when the centre pedestal cover was removed.
2. The PROBES AUTO/MANUAL switch position check was not included on the Newfoundland and Labrador Government Air Services CL-415 checklist.
3. The flight crew was occupied with other flight activities during the scooping run and did not notice that the water quantity exceeded the predetermined limit until after the tanks had filled to capacity.
4. The flight crew decided to continue the take-off with the aircraft in an overweight condition.
5. The extended period with the probes deployed on the water resulted in a longer take-off run, and the pilot flying decided to alter the departure path to the left.
6. The left float contacted the surface of the lake during initiation of the left turn. Aircraft control was lost and resulted in collision with the water.
» CADORS 2013A0595
Official accident investigation report
|investigating agency: ||Transportation Safety Board (TSB) - Canada |
|report status: ||Final|
|report number: ||A13A0075|
|report released:||28 August 2014|
|duration of investigation: ||1 year and 2 months|
|download report: ||
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