Incident
On 15 April 2011 at 1111 UTC, a Piper PA-34-200 Seneca, registration G-AZOT, was landing on Runway 03 at Glenswinton, a private airstrip near Castle Douglas, Dumfries and Galloway. The pilot, who held an Airline Transport Pilot's Licence with 2,060 hours total flying experience (71 on type), was conducting a private flight with one passenger. After touchdown on the runway centerline, the pilot retracted the flaps and applied the brakes. The right brake felt light, leading him to suspect it had failed. He then increased pressure on the left brake pedal, applied full right rudder, and pumped the right brake. The right brake became more effective as the aircraft slowed, but the pilot could not prevent the aircraft from drifting left of the centerline and departing the left side of the runway. When approximately 70 m from the end of the runway and at low speed, the left wingtip struck a tree and the left propeller contacted the ground.
Aircraft Information
The aircraft was a 1971-model Piper PA-34-200 Seneca, powered by two Lycoming IO-360-C1E6 piston engines. The pilot's last 90 days included 36 hours of flying, with 6 hours in the last 28 days.
Airfield and Landing Conditions
Glenswinton's runway is 380 m long with a compacted gravel surface and a 5% upslope in the 03 direction. The wind was light and variable. The pilot estimated the landing distance required at 366 m using the Normal performance chart, accounting for temperature, landing weight, zero wind, and a 2% upslope (the maximum on the chart). He was using a short-field landing technique but lacked the short-field performance chart. He considered the 5% upslope favorable for reducing landing distance, and the absence of obstacles allowed a touchdown close to the threshold.
Braking Performance
Subsequent inspection revealed corrosion and only partial friction surface contact on the right brake disc. The aircraft's braking performance was probably degraded due to the poor condition of the right brake unit. Additionally, the compacted gravel runway surface may have been less effective for braking than a conventional paved surface. Aircraft performance charts are based on testing of new aircraft in ideal conditions, which may not reflect real-world degradation.
Aftermath
No injuries were reported among the two occupants. Damage was limited to the left wingtip, rear spar, left propeller, left engine, and left landing gear. The pilot submitted an Aircraft Accident Report Form to the AAIB.
The CAA recommend in Safety Sense Leaflet 7 'Aircraft Performance' that a factor of 1.43 be applied to the landing distance required for all flights, and note that any benefit from runway slope should be considered a bonus.