What happened
On 23 September 2006, a Bolkow BO 208C Junior, registration G-ATXZ, was performing a series of touch-and-go landings at Tatenhill Airfield in Staffordshire. Following the second takeoff, the aircraft was in its normal climb-out phase when the nose landing gear suddenly detached from the airframe.
Upon being notified by Air Traffic Control that the gear had fallen away, the pilot elected to return to the airfield. The pilot managed to keep the nose of the aircraft elevated for as long as possible while the engine was shut down and the propeller was windmilling. However, as the aircraft's speed decreased, the nose dropped, causing the aircraft to weathercock into the wind and veer off the runway into a grass area adjacent to the strip. There were no injuries to the pilot during the incident, though the aircraft sustained damage to the engine cowling, exhaust, carburettor airbox, propeller, and nose landing gear.
The investigation
The AAIB investigation involved a metallurgical examination of the detached nose landing gear assembly at Qinetiq. The examination focused on the outer tube of the gear, which had been fitted to the aircraft 51 airframe hours prior to the accident as a replacement part.
Investigators found that the outer tube had fractured between two holes located between the bronze bushes. While heavy corrosion and post-failure damage obscured much of the surface detail, the examination revealed areas of flat, fatigue-like crack growth adjacent to the side holes. The tube also showed evidence of previous repairs and light grinding marks, suggesting the component had been in use before its most recent application of paint.
Findings
- The nose landing gear outer tube failed due to fatigue crack growth in the area between the bronze bushes.
- The replacement gear assembly had been previously repaired, but the associated documentation did not confirm that any inspections for cracking had been performed.
- There was currently no requirement under existing Airworthiness Directive No 72-92 to inspect the outer tube for cracks following a heavy landing or gear damage.
Safety action
- It is recommended that the European Aviation Safety Agency (EASA) review the inspection requirements of Airworthiness Directive No 72-92 to ensure the continued airworthiness of Bolkow BO 208 nose landing gears.
- It is recommended that the Civil Aviation Authority (CAA) review the airworthiness category under which UK-registered Bolkow BO 208 aircraft are operated.