What happened
On May 27, 2013, a Piper PA-18-150 Super Cub, registration PH-SER, was performing a series of takeoff climbs at Midden Zeeland Airfield (EHMZ). The flight was an instructional session intended to help the pilot gain experience for future advertising banner-towing operations.
During the sixth takeoff attempt on runway 27, the engine began to sputter and lose power at approximately 75 feet altitude. The instructor, who was seated in the rear, took control of the aircraft. To avoid a treeline to the right and obstacles including a creek, camping caravans, and debris, the instructor initiated a left turn. This maneuver caused the aircraft to lose altitude rapidly. The plane struck a body of water in a nearby excavation site, causing the aircraft to flip over and become totally destroyed. The pilot sustained one light injury.
The investigation
The Dutch Safety Board (OVV) examined several potential causes for the engine failure. Investigators looked into the possibility of carburetor icing, noting that the ambient temperature and dew point were conducive to ice formation. They also investigated the fuel quality, as the aircraft was authorized to use automotive gasoline via a Supplemental Type Certificate. The investigation found that the automotive fuel in the right tank did not meet standard requirements, specifically lacking necessary volatile components.
Additionally, the board looked into the aircraft's maintenance and hardware, including whether a non-standard rubber ring on the fuel cap could have caused a vacuum in the tank. The investigation also noted that the pilot was not wearing seatbelts, as they restricted his ability to operate the flaps, though the impact with the water mitigated the potential for serious injury.
Findings
- The exact cause of the engine failure could not be definitively determined.
- The automotive fuel in the right tank was substandard, with a volatility of only 4.7% compared to the required minimum of 2 .7%, which may have caused poor combustion.
- The instructor's decision to execute a left turn after the engine failure deviated from basic single-engine engine-failure procedures and introduced significant risk.
- The pilot's failure to wear seatbelts increased the risk of head and chest injuries during a high-energy impact.