What happened
On 8 August 2008, a Diamond DA 42 with registration SE-LYK was conducting an IFR flight from Stockholm/Bromma to Eskilstuna and Västerås. During the climb, at an altitude of approximately 2,800 feet, the right engine ceased operation. The pilot attempted several restarts, but the engine remained non-functional.
As the aircraft was unable to maintain its altitude, it began descending at a rate of roughly 30 and 300 feet per minute. While attempting to return to Stockholm/Bromma, the aircraft drifted right of the runway. The pilot subsequently searched for an alternative landing site and identified a wooded area. The aircraft impacted the trees and immediately caught fire. While the three passengers managed to exit the wreckage, the pilot was trapped in his seat and required assistance from bystanders to be freed.
The investigation
The Swedish Accident Investigation Board (SHK) examined the mechanical, operational, and medical aspects of the crash. Technical analysis of the right engine revealed that a fault in a solenoid valve within the propeller pitch change mechanism had caused the propeller to move to the fully feathered position, leading to the loss of power.
Investigators also reviewed the aircraft's weight and balance, finding that the aircraft was overloaded by approximately 200 kg. Furthermore, the investigation looked into the pilot's medical status, noting that the pilot was taking medication for a metabolic disorder and long-term exhaustion, which could have impacted concentration during the emergency.
Findings
- The engine failure was caused by a component failure in the propeller pitch change mechanism.
- The aircraft was overloaded, exceeding its maximum authorized take-off mass.
- The pilot did not apply rudder trim during the single-engine flight, likely resulting in a side-slip that hindered climb performance.
- The pilot was using medication that would typically preclude the issuance of a valid medical certificate.
- The aircraft's fuel levels in the auxiliary tanks could not be accurately determined by the crew.
- During the rescue operation, there was a lack of awareness regarding the specific risks and decontamination needs associated with burning carbon fiber composites.