What happened
On a scheduled instrument flight rules round-trip mission originating from Calgary International Airport (CYYC), a Piper PA-3im Navajo operated by Airborne Energy Solutions Inc. experienced a series of fuel-related engine issues. The flight, which included a stop at Hinton/Entrance Aerodrome (CEE4), was being flown by a solo pilot who had initially determined that sufficient fuel was available for the return leg to Calgary without refueling.
During the cruise portion of the flight, the pilot noticed fluctuating fuel pressure and erratic performance from the left engine. In response, the pilot switched the left engine's fuel source from the left outboard tank to the left inboard tank. To mitigate concerns regarding remaining fuel levels in the left wing, the pilot also engaged the cross-feed system to supply the left engine from the right-side fuel system.
As the aircraft approached Calgary International Airport, the right engine ceased operation. The pilot responded by securing the engine, feathering the propeller, and declaring a Mayday to Air Traffic Services while continuing the approach. Shortly after, the left engine also failed. The pilot performed a forced landing on a golf course situated just south of the approach end for Runway 35R, coming to rest roughly 0.5 nautical miles south of the threshold. The pilot sustained minor injuries, but the aircraft was substantially damaged. No fire occurred at the crash site.
Findings
Post-accident inspections of the aircraft revealed that the left-hand fuel selector was set to the outboard position, the right-hand fuel selector was in the off position, and the cross-feed valve was in its normal off position. Investigation of the fuel tanks showed that the left inboard, left outboard, and left nacelle tanks were completely empty. While the right nacelle tank was also depleted, approximately 24 USG remained in the right inboard tank and approximately 29 USG remained in the right outboard tank. The investigation concluded that the engines failed due to fuel exhaustion.