What happened
On 16 April 2006, a Van's RV-9A, registration G-CCZT, was performing a private flight at Bicester Airfield in Oxfordshire. The aircraft, carrying a pilot and one passenger, was on final approach at approximately 65 kt. As the pilot initiated the landing flare, the control stick became disconnected from the flying control system, causing the aircraft to pitch into a sudden nose-down attitude.
During this uncontrolled descent, the nose landing gear struck the ground, causing the aircraft to dig into the grass surface. The impact resulted in the collapse of the nose gear and caused the propeller, engine mounting, and cowling to sustain damage as the aircraft pitched forward onto its nose before settling back onto its main gear. There were no injuries to the two occupants.
The investigation
Investigators examined the dual cockpit control system to determine why the connection failed. They discovered that the right-hand control stick was held within the flying control system's protruding tube solely by the friction of a "push fit" arrangement. There was no mechanical fastener, such as a bolt, to provide a positive secure connection.
Further review of the manufacturer's drawings revealed that they did not specify any requirement for a positive secure connection between the dual control stick and the flying control system. Additionally, research conducted by the Popular Flying Association (PFA) indicated that similar attachment arrangements were used on Van's RV-7/7A aircraft.
Findings
- The primary cause of the accident was the disconnection of the control stick from the flying control system during the landing flare.
- The dual control stick was only secured by friction within the tube of the flying control system, lacking a positive mechanical attachment.
- The manufacturer's design drawings did not require a bolt or nut to secure the junction between the dual stick and the control system.
Safety action
Following the investigation, the PFA issued mandatory airworthiness information (MOD/320/002) to address the security of control columns in PFA aircraft. The AAIB issued two safety recommendations to Van's Aircraft, advising the introduction of a Service Bulletin for RV-7, RV-7A, RV-9, and RV-9A models to implement a positive attachment for the dual control stick.