What happened
On 25 July 2019, a Bolkow 207, registration D-EFQE, was parked on the dispersal apron at RAF Odiham during a station event. To improve cockpit ventilation in the heat, the pilot had left the aircraft doors open, though rudder and elevator gust locks had been applied. While the pilot was maneuvering the aircraft to face into a strengthening breeze, a North American T-6 Harvard 4, registration G-BJST, taxied into a position tail-to-tail with the Bolkow. The pilot of the Harvard increased engine RPM briefly before shutting down.
The pilot of the Bolkow 207 observed that the propwash from the Harvard's engine had overcome the installed gust locks. At the time, the pilot believed any resulting damage was only superficial. However, during the subsequent return flight, the pilot experienced abnormal control response regarding the elevators and requested a straight-in approach to ensure a safe landing. There were no injuries and the aircraft landed without further incident.
The investigation
Investigators examined the aircraft following the flight and discovered that the tension in both the rudder and elevator control cables had fallen outside of the permitted limits. No visible external damage was found on the airframe. Records showed that the aircraft had completed an annual maintenance check just one week prior, at which time all cable tensions had been verified as being within limits.