Aircraft and Crew
The aircraft involved was a float-equipped de Havilland DHC-2 Beaver, registration C-FEYQ, serial number 465, operated by Blue Water Aviation Services. The pilot held a valid Canadian commercial pilot license, rated for land and sea operations. According to Transport Canada and company documentation, the pilot was qualified and fit to perform the flight.
Flight Details
On the day of the accident, the aircraft departed Bissett, Manitoba, at approximately 0910 central daylight time (CDT). The load consisted of the pilot, three passengers, passenger baggage, and two 16-foot canoes strapped to the float strut assemblies. The flight was to transport canoeists to Sasaginnigak Lake, approximately 38 miles north of Bissett. Approximately 18 minutes into the flight, the engine low fuel pressure warning light illuminated and the engine began to lose power. The pilot switched tanks from the centre fuel tank to the front tank and manually operated the fuel wobble pump. The engine sputtered but did not regain power. The aircraft descended over land, and the pilot was forced to put the aircraft down through trees into a rocky area. The aircraft overturned during touchdown.
Occupants and Rescue
The pilot and three passengers exited the aircraft uninjured. The aircraft was spotted several hours later by an overflying aircraft. There was no emergency locator transmitter (ELT) on board. A helicopter was dispatched, and the occupants were transported to a nearby hospital for observation.
Weather and Flight Conditions
The weather observation for Bissett at 0900 CDT indicated surface temperature 28°C, temperature at 1000 feet 30°C, and winds less than 10 knots from the south. This was the pilot's third flight of the day. Company policy was to fly external loads early in the morning when temperatures were cooler. The first flight was flown approximately four hours earlier with three passengers and one canoe, at a temperature of about 18°C. The second flight consisted of three legs. No performance problems were reported on those flights. The occurrence flight would have been the pilot's last external load flight that day.
Fuel System and Power Loss
Prior to the occurrence flight, the pilot added approximately 50 liters (13.25 US gallons) of fuel to the centre tank, which was nearly empty. The front tank already contained approximately 113 liters (30 US gallons) from the previous flight. The pilot's normal practice was to burn fuel from the centre tank first, then switch to the front tank for landing. At a fuel burn rate of approximately 25 US gallons per hour (gph), the pilot estimated a duration of about 32 minutes on the centre tank. The flight up to the time of power loss was flown entirely on the centre tank.
An examination of the wreckage approximately one week later focused on the fuel system. The aircraft had been inverted since the accident, and most fuel had drained or evaporated. Recovered fuel was free of water and contamination. Engine and airframe fuel system screens were clean and unobstructed. Fuel tanks and lines were free from foreign obstructions. The fuel selector valve was found selected to the forward tank and operated normally.
Calculations based on the added fuel and flight time indicated that the engine would have needed to burn a minimum of 44 gph to empty the centre tank, which was unlikely given the average burn rate of about 25 gph. Therefore, the illumination of the fuel pressure warning light and subsequent loss of engine power were not a result of the centre tank running dry. The only anomalies found in the fuel delivery system that could account for the power loss were a restriction in the inline fuel check valve at the wobble pump location and a kink in the main engine fuel feed line. A restriction in the check valve would probably not result in a power loss, as fuel could still be drawn through internal check valves in the wobble pump, but with additional line losses. The prior problem of the wobble handle moving up and down indicated that the inline fuel check valve was restricted to the extent that fuel was being drawn through the wobble pump to compensate.
Regulatory Context
The company's operations manual prohibited the carriage of passengers when external loads were carried unless authorized in the aircraft's Type Certificate or Supplemental Type Certificate (STC). The DHC-2 Beaver Type Certificate does not authorize passengers with external loads. The company did not hold an STC, and no documentation of an exemption was found. There is no known STC allowing the external carriage of two canoes.
Canadian Aviation Regulation (CAR) 703.25 prohibits external loads with passengers unless authorized. However, an exemption published in Commercial and Business Aviation Advisory Circular No. 0209 (CBAAC 0209) allows operators to carry external loads and passengers simultaneously under certain conditions. The exemption requires that operators meet specific conditions and amend their operations manual. A review of company and Transport Canada documentation indicated that none of the conditions had been met.
Interviews with Transport Canada inspectors revealed varying interpretations of CBAAC 0209. There was confusion regarding when the Type Certificate governed external loads and when the exemption applied. Inspectors expressed concern that CBAAC 0209 contained no finite restrictions on weight, quantity, and dimensions, potentially allowing large, non-aerodynamic loads that could exceed aircraft performance capabilities. The wording was considered ambiguous.
The investigation found that most company senior operations personnel and the pilot had limited knowledge and understanding of regulations governing external loads. Carriage of external loads with passengers was common practice at the company. Some training on external loads had been conducted, but it was neither formal nor documented. The training information available from the company's operations manual and training program was incomplete.
CBAAC 0209 does not permit exceeding aircraft performance capabilities. It requires that when passengers plus external loads are carried, the maximum take-off weight be reduced by twice the weight of the external load. The pilot was aware that the external load and high temperatures would affect performance and limited the load in an ad hoc manner. At take-off, the aircraft was 350 to 400 pounds below its maximum take-off weight of 5090 pounds.