What happened
On 15 July 2004, a modified Pitts S-1C, registration G-SWUN, was performing a private flight at Wickenby, Lincolnshire. The weather conditions were favorable, with a light northerly wind of approximately 5 knots. The pilot completed three circuits using the 600-metre tarmac runway (Runway 33).
During the full-stop landing of the third circuit, the aircraft was traveling at a low speed. As the pilot applied light braking, the aircraft underwent a sudden and violent ground loop to the right. During this maneuver, the propeller and the left lower wing tip made contact with the ground. The momentum caused the aircraft to pitch forward over its nose, eventually coming to rest in an inverted position, supported primarily by the stern post.
Following the impact, the pilot successfully shut off the fuel and electrical systems, opened the canopy, and exited the aircraft. There were no injuries to the pilot.
The investigation
The investigation was based on the aircraft accident report submitted by the pilot and subsequent telephone inquiries by the AAIB. The examination focused on the sequence of the landing and the physical damage sustained by the aircraft, which included engine shock loading and damage to the tail fin, wing tip, and upper wing.
Findings
- The aircraft's design, characterized as a 'short-coupled' model, contributes to highly active handling characteristics, particularly during the takeoff and landing phases.
- The sudden ground loop occurred while the aircraft was at a low speed during the braking phase of the landing.
- The pilot noted that the use of a crash helmet and a high-quality five-point harness likely prevented injury during the inversion.