What happened
On 2 April 2022, an Extra NG, registration G-MIIL, was performing a private flight near Bicester Airfield. After completing a series of aerobatic manoeuvres, the pilot was returning to base in straight and level flight at approximately 1,900 ft amsl. While cruising at 184 KIAS, the aircraft's canopy suddenly disintegrated without warning.
The sudden loss of the canopy caused severe wind blast and obscured the pilot's vision, as his glasses and headset were blown away. Unable to maintain control or navigate back to the airfield, the pilot, who was wearing a parachute, chose to bail out. Following his departure, the aircraft entered a rapid descent and collided with an unoccupied, newly constructed three-storey block of flats in Upper Heyford. The impact destroyed the aircraft and caused damage to the building, though no one on the ground was injured. The pilot sustained serious injuries, including the loss of sight in his right eye, but survived the parachute descent.
The investigation
Investigators examined the wreckage of the aircraft and recovered approximately 75% of the canopy fragments from a nearby area. Analysis of the canopy frame revealed significant manufacturing inconsistencies. Specifically, the bonding between the inner and outer carbon fibre layers was inadequate in several areas, showing evidence of porosity and adhesive failure.
Data from the aircraft's Electronic Flight Instrument System (EFIS) confirmed that the aircraft was operating within its certified flight envelope at the time of the failure. The investigation also considered whether the canopy had been improperly locked; however, the evidence suggested that the aerodynamic forces during the break-up sequence were sufficient to wrench the shoot bolts out of their lugs once the structural integrity of the frame was compromised.
Findings
- The canopy transparency suffered catastrophic failure due to fatigue crack development.
- These cracks were initiated by localised stresses caused by inadequate bonding between the inner and outer components of the canopy frame.
- The lack of uniform bonding created differential loads that promoted the growth of cracks in the acrylic material until they reached a critical length.
- The pilot's survival was due to the use of a parachute, though the lack of a helmet or visor contributed to the severity of his facial injuries.