Piper PA-25 Pawnee Runway Excursion at Aeródromo de la Axarquía (EC-BXT)

Incident Overview and Aircraft Details On July 3, 2005, at 10:30 local time, a Piper PA-25 Pawnee with registration EC-BXT, operated by Alvair, experienced a runway excursion at the Aeródromo de la Axarquía in Vélez-Málaga, Málaga. The aircraft, manufactured in 1970 and powered by a single Lycoming O-540-G1 A5 engine, was conducting a commercial aerial work operation, specifically a banner-towing flight. The pilot, a 22-year-old commercial pilot with 400 total flight hours and 20 hours on type, was the sole occupant and remained uninjured. ## Sequence of Events and Damage Prior to the incident, the aircraft completed a reconnaissance circuit around the airfield. During landing on runway 13, the pilot applied both brakes simultaneously but reported that the left brake did not respond. The aircraft veered to the right, crossed the right margin, descended a small embankment, and struck a perimeter fence. The impact caused minor damage to the left wingtip, leading edge, left horizontal stabilizer, propeller, and left landing gear. The left landing gear had already been replaced at the time of the post-incident inspection. ## Investigation Findings and Probable Cause The investigation revealed that the left brake caliper suffered a static fracture near a bolt hole, a result of excessive wear on the brake pad. The worn pad had created excessive clearance, causing it to oscillate transversely on its axis and exert abnormal stress on the caliper. The operator had discarded the brake pad before inspection, preventing a direct examination, but evidence indicated it was worn beyond functional limits. The abrupt braking action over a short distance on the 637-meter runway further contributed to the caliper failure. The probable cause was the left brake caliper fracture due to excessive brake pad wear, resulting from inadequate maintenance, which led to loss of directional control and the subsequent runway excursion and collision with the fence.