What happened
On June 9, 2019, at approximately 20:39, a Piper PA-23, registration N3294P, crashed approximately 1 km east of the runway at Múlakot airport. The aircraft was engaged in a private flight with two pilots and three passengers, traveling from Vík í Mýrdal to Djúpivogur, with a planned return to Múlakot. The flight had previously visited Hella and Djúpivogur, but no additional fuel was taken during these stops.
During the final approach to runway 29 at Mú．lakot, the aircraft was performing several low passes and touch-and-go maneuvers. Witnesses observed the aircraft flying at a low altitude and low speed. During the final turn toward the runway, the pilot noticed the RPM of the left engine decreasing, followed by a similar drop in the right engine. As the aircraft entered a left turn, the left wing lifted, causing the aircraft to cartwheel and crash. The impact caused the aircraft to break apart, and a fire ignited in the left wing area. The accident resulted in three fatalities and two serious injuries.
The investigation
The RNSA examined the aircraft wreckage, fuel system components, and fuel quantity transmitters. Investigators found that the main fuel tanks were nearly empty, with only about 6 liters of unusable fuel remaining in the right tank. While the aircraft was equipped with auxiliary tanks, the fuel selector was set to the main tanks.
Technical analysis of the fuel quantity transmitters revealed that the right main tank transmitter showed higher resistance in its lowest position, which likely caused the cockpit gauge to display more fuel than was actually present (approximately 1/8 remaining). The investigation also confirmed that the aircraft had been flying for approximately 3 hours and 20 minutes that day, exceeding the safe limits for the fuel remaining in the main tanks.
Findings
- The primary cause of the accident was fuel exhaustion in both engines.
- The left engine lost power first, followed by the right engine during the final turn.
- A faulty fuel quantity transmitter likely provided an inaccurate, higher reading of the remaining fuel in the right main tank.
- The pilots had limited experience operating the Piper PA-23.
- The crew did not utilize the auxiliary fuel tanks during the flight, despite the low levels in the main tanks.
- There was a lack of available Avgas 100LL fuel at the planned refueling stop in Höfn.