What happened
On 25 August 2006, a Zenair CH6 and 01UL, registration G-YOXI, was performing a low-level flypast over a farm strip near Bramley, South Yorkshire. The flight was intended to allow the pilot to view a newly constructed landing strip. During the maneuver, the aircraft performed a steep descent before leveling out to fly along the strip. As the aircraft began to climb at the end of the strip, the right wing failed, causing both wings to fold upwards.
The aircraft subsequently crashed into an adjacent field, triggering a severe post-crash fire. Both the pilot and the passenger sustained fatal injuries. Witnesses at the scene observed the aircraft flying at a very low altitude, approximately 30 feet above the ground, and noted the sudden structural failure during the climb.
The investigation
Investigators examined the wreckage and established that the aircraft' and the right wing front spar had experienced extreme stress. Although the post-crash fire had damaged much of the aluminum, examination of the wing structure revealed buckling indicative of an overstress in upload. The investigation also found that the aircraft was likely operating near its maximum all-up weight.
Analysis of the flight path suggested the aircraft had cleared nearby power lines with a significant margin, meaning the wires were not the cause of the accident. The investigation also considered the pilot's previous experience with flex-wing microlights, noting that different handling characteristics and stick forces might have influenced the application of excessive loads during maneuvers.
Findings
- The primary cause of the accident was the structural failure of the wing due to excessive loads applied to the most vulnerable point of the wing.
- The aircraft was likely operating close to its maximum allowable weight, which increased the stresses during the maneuver.
- The pilot's transition from flex-wing aircraft to fixed-wing microlights may have resulted in a different perception of the stick forces required to maneuver the aircraft safely.
- It is possible that previous high-speed or high-g maneuvers had weakened the airframe over time.