Synopsis
On 6 October 2007, a Piper PA-32-300 (registration N2989M) landed at Newmarket Racecourse, Cambridgeshire, after a flight from Middleham. Immediately after touchdown, the pilot retracted the flaps to prevent floating and improve braking. The aircraft passed over an undulation, became airborne again, and made a firm landing. No inspection beyond the pre-flight check was conducted, and the aircraft returned to Middleham without incident. Two days later, during a routine 50-hour maintenance inspection, significant structural damage was discovered on both lower wing skins and the right wing leading edge. Wing spars were distorted. The damage was considered to have weakened the wing structure such that there was a risk of structural failure during the return flight.
History of the Flight
The private flight originated at Middleham and arrived at the airstrip at Newmarket Racecourse. After a normal approach and touchdown, the pilot immediately retracted the flaps to ensure positive ground contact and reduce float. Shortly after touching down, the aircraft passed over an undulation in the runway surface, causing it to become airborne again. The pilot attempted to minimize the sink rate with power but made what he described as a firm touchdown. Based on his experience, the pilot did not consider the landing excessively firm and judged that no additional inspection was required before the return flight.
Fuel
The aircraft departed Middleham with approximately 70 US gallons of fuel evenly distributed across its four wing tanks. The PA-32-300 has two inboard tanks (25 US gallons each) and two outboard tanks (17 US gallons each). The normal procedure is to consume inboard fuel before outboard fuel, presumably to provide bending moment relief. Given a flight time of about 1.5 hours and a fuel burn of approximately 14 US gallons per hour, the outer wing tanks would have remained largely unused at the time of landing.
Landing Technique
The pilot employed a short field landing technique of retracting the flaps immediately after touchdown. This was intended to reduce lift and allow earlier wheel braking. A secondary effect is reduced aerodynamic drag, decreasing deceleration. If the aircraft becomes airborne during this phase, there may be insufficient lift to reduce the subsequent rate of descent. While the pilot did not consider the landing firm enough to warrant additional inspection, the damage, particularly the wing leading edge deformation, could have been easily observed during a pre-flight inspection. Operating the aircraft in its damaged condition would have severely compromised the wing's ability to carry design flight loads.
Damage and Findings
During the 50-hour inspection on 8 October, buckling was found on the lower wing skins outboard of the landing gear and on the right wing leading edge. Removal of wing skins revealed compressive buckling and cracking of the lower spar webs outboard of the main landing gear, indicating a significant download had been applied to the outer wings. Both wings were subsequently removed for repair.