What happened
On June 27, 2019, a Piper PA-28-161, registration YU-DDB, was performing a return flight to Târgu Mureș Airport after completing a mission to distribute rabies vaccine baits. While descending through 6,000 feet over a forested mountain area in the Mădăraș locality, the pilot experienced significant engine vibrations and a loss of power after increasing the throttle to maintain speed.
Despite attempts to re-establish power by repositioning the engine control levers, the engine continued to lose power and the airspeed decreased. To avoid a stall, the pilot maintained a descent attitude at approximately 65-70 knots. As the aircraft approached the trees, the pilot deployed the flaps to reduce impact speed and pitched the nose up to ensure the horizontal empennage and fuselage underside struck the trees first. The aircraft impacted the fir trees and subsequently caught fire, resulting in the near-total destruction of the aircraft. The pilot and the vaccine distribution operator were rescued by a helicopter and transported to a hospital with two serious injuries.
The investigation
The investigation examined the aircraft's configuration, maintenance history, and the operational environment. It was established that the aircraft had been modified to carry a vaccine scattering device. However, the investigation found that the aircraft was being operated outside of its technical specifications. Specifically, the right-hand pilot seat, which was required by the approved modification project to accommodate the operator, had been removed. The operator was instead positioned on the floor of the aircraft without a dedicated seat or safety restraint.
Furthermore, the investigation revealed discrepancies in the weight and balance documentation and noted that the operator had a history of using non-compliant aircraft configurations for these missions. The investigation also reviewed the meteorological conditions, noting a high probability of carburetor icing during the descent.
Findings
- The aircraft was configured in a manner that deviated from the approved EASA-approved modification project.
- The vaccine scattering device operator was unsecured and lacked a dedicated seat.
- The operator's safety culture showed deficiencies, as using non-compliant aircraft configurations had become a practice.
- Carburetor icing was the most probable cause of the engine power loss during the descent.
- The aircraft had been involved in a previous accident in Bulgaria under similar operational circumstances.