During an aerobatic flight, as the pilot applied a full left aileron control input, the centre hinge attachment for the right aileron failed. This allowed the right aileron to bend up in the centre and fail before detaching from the aircraft. Only a small inboard section of the aileron remained attached. The pilot had sufficient control remaining to make a safe landing.
The investigation found that the centre hinge attachment for the right aileron failed due to fatigue cracks developing to such an extent that the parts were no longer able to carry the required load. These fatigue cracks had multiple origins indicating that they were not due to a material feature or flaw.
The aircraft manufacturer has issued a Service Letter to all known owners recommending regular detailed inspections of similar aileron centre hinge attachments. The UK Light Aircraft Association has contacted all affected owners in the UK to ensure they are aware of this mandatory Service Letter.