What happened
On 4 March 2014, a Mainair Blade, registration G-CDAG, was performing a private flight from a grass runway near Over Farm, Gloucester. Following a successful solo flight to assess the runway conditions, the pilot prepared for a second flight carrying a passenger. Although the pilot had noted soft ground and patches of standing water during his initial inspection, he proceeded with the takeoff.
During the takeoff roll, the aircraft failed to accelerate at the expected rate. At a point approximately three-quarters of the way down the 410-metre runway, the pilot elected to abort the takeoff. As the throttle was closed, the nosewheel likely became airborne and then subsequently loaded with weight as the pilot pulled back on the control bar. The nosewheel dug into the soft surface, causing the aircraft to flip onto its back. The impact resulted in serious injuries to both the pilot and the passenger, with the aircraft sustaining damage to its wing, propeller, front strut, and monopole.
The investigation
The AAIB investigation examined the runway conditions and the pilot's actions during the aborted takeoff. The investigation established that the pilot had chosen a different path for the second takeoff to avoid existing ruts, which likely led the aircraft into even softer ground. The investigation also reviewed the aircraft's weight, noting that the second takeoff weight of 370 kg was 6% higher than the previous solo flight.
Findings
- The primary cause of the accident was the nosewheel digging into the soft ground during the aborted takeoff.
- The pilot's decision to use a different line on the runway to avoid ruts likely resulted in encountering more unstable terrain.
- The aircraft's lack of normal acceleration was due to the soft nature of the runway surface.
- The inversion was likely triggered by the nosewheel becoming airborne and then being forced into the ground as the pilot applied back pressure on the control bar while closing the throttle.