What happened
On 25 July 2014, a Pietenpol Air Camper, registration G-OHAL, was conducting a private familiarisation flight from Turweston to Shenington Airfield. The flight was being conducted by a pilot acting on behalf of an aircraft syndicate. To ensure the aircraft's centre of gravity (C of G) remained within acceptable limits, a member of the syndicate flew as a passenger in the forward cockpit.
During the approach to Runway 05 at Shenington, the pilot performed a steeper-than-normal descent using a sideslip technique to avoid an obstruction on the grass area. As the aircraft neared the ground, the pilot recovered from the sideslip and attempted to flare. However, despite moving the control column fully rearwards, the aircraft failed to enter a flare and struck the ground heavily. The impact caused the main landing gear to collapse, the propeller to strike the ground, and the landing gear strut to penetrate the lower fuselage. There were no injuries to the two occupants.
The investigation
The AAIB examined the aircraft and found no evidence of mechanical defects in the rudder or elevator control circuits. Testing of the pitot-static system confirmed that the airspeed gauges were accurate.
Investigators recalculated the aircraft's weight and balance, confirming that the aircraft was at its maximum takeoff weight and that the C of G was at its forward limit. While the takeoff speed was consistent with calculations, the pilot's reported climb and stall speeds were significantly higher than those recorded during the aircraft's recent airtest. The investigation focused on how the forward C of G and the flight profile contributed to the loss of control during the flare.
Findings
- The aircraft was operating at its forward C of G limit, which increased the downforce required on the horizontal tail for trim.
- The pilot's use of a steep descent and sideslip resulted in a higher than normal rate of descent.
- The aircraft was flying at a low airspeed, which, combined with the low engine power, reduced the effectiveness of the elevator.
- The lack of elevator effectiveness prevented the pilot from successfully initiating a flare before touchdown.