What happened
On a flight from Grande Prairie to Grande Cache, Alberta, a Sarvair Aviation Ltd. Robinson R44 helicopter, registration C-FOBX, experienced a sudden loss of engine power and main rotor RPM while climbing over rising terrain. The pilot attempted to descend into a valley to regain rotor speed, but the engine performance continued to degrade. The pilot was forced to perform an emergency landing into a wooded area, where the aircraft came to rest on its right side.
The impact caused the passenger to fall onto the pilot, resulting in one serious injury to the pilot, while the passenger remained uninjured. The crew remained at the crash site for over 15 hours before being rescued. The search and rescue response was significantly hindered because the aircraft's emergency locator transmitter (ELT) failed to activate immediately upon impact.
The investigation
The investigation examined the mechanical state of the Avco Lycoming O-540-F1B5 engine and the functionality of the onboard emergency equipment. Investigators found that the helicopter was properly maintained, within weight limits, and had sufficient fuel. However, the investigation focused on why the engine failed and why the rescue was delayed.
Regarding the rescue delay, investigators identified several issues: a loose battery connector in the ELT prevented it from transmitting until the wreckage was struck by a tree; the use of different geographic coordinate formats by various agencies caused location errors; and a lack of a common communication frequency among responders complicated coordination. Additionally, the pilot's unfamiliarity with the 911 functions of a newly purchased SPOT satellite messenger contributed to the confusion during the initial stages of the search.
Findings
- Carburetor icing was the likely cause of the engine power loss and subsequent loss of rotor RPM.
- A loose electrical connection between the battery and the transmitter prevented the ELT from functioning correctly.
- The ELT's single-axis gravity switch may not trigger if the impact force is not aligned with its specific axis.
- Inconsistencies in geo-referencing formats between different search and rescue agencies led to inaccuracies in the reported accident location.
- Unfamiliarity with the specific emergency functions of the SPOT satellite messenger delayed the initiation of rescue efforts.
- The lack of a unified communication frequency among various rescue participants hindered the coordination of the search efforts.