What happened
On June 20, 2008, a Fairchild SA226-T(B) Merlin, registration LN-SFT, crashed into the sea approximately 10 nautical miles west of Sotra, Norway. The flight was being conducted as a skill test for a newly hired first officer for the operator Helitrans. The crew consisted of the pilot, an instructor, and a civil aviation authority examiner.
During the flight, which was conducted in Instrument Meteorological Conditions (IMC) with heavy rain and turbulence, the crew attempted a demonstration of slow flight and a stall. During the maneuvers, the aircraft entered a deep stall from which recovery was impossible. The aircraft descended approximately 6,200 feet in 37 seconds before impacting the water. All three occupants were killed in the accident.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the sequence of events leading to the loss of control. The investigation looked into the aircraft's configuration, noting that LN-SFT had been modified with external sensors and antennas for coastguard duties. Computational Fluid Dynamics (CFD) analysis was performed to determine if these modifications affected stability. While the modifications increased drag, the analysis indicated they did not significantly degrade stability during slow flight.
The investigation also reviewed the training and certification processes. It was noted that the crew was operating under challenging weather conditions, including winds up to 40 knots. The investigators also examined the status of the Stall Avoidance and Stability Augmentation System (SAS²), finding that the circuit breaker for this system had been pulled during a previous flight test the day before and had not been reset for the fatal flight.
Findings
- The primary cause of the accident was the aircraft entering a deep stall during a maneuver requested by the examiner.
- The Stall Avoidance and Stability Augmentation System (SAS²) was non-functional because the circuit breaker had been pulled during a previous flight and was not re-engaged.
- The flight was conducted in highly unsuitable weather conditions, characterized by turbulence, rain, and low ceilings.
- There was a lack of coordination and communication between the crew members during the flight.
- The training and certification procedures for the type were complex and subject to differing interpretations between aviation authorities.