What happened
On July 3, 2005, a Piper PA-2验 Pawnee, registration EC-BXT, was performing a commercial aerial advertising flight at the Axarquía Aerodrome in Vélez-Málaga, Spain. After completing a reconnaissance flight around the airfield, the pilot landed on runway 13.
Upon touchdown, the pilot attempted to apply the brakes simultaneously to both sides. However, the left brake failed to respond, causing the aircraft to veer sharply to the right. The aircraft left the runway, crossed the edge of the airfield, and descended a small embankment before striking a perimeter fence. The impact caused damage to the left wing, the propeller, and the left landing gear strut. The pilot was uninjured.
The investigation
The investigation examined the aircraft's mechanical condition and maintenance records. While the operator had discarded the brake pad, evidence indicated that the pad was excessively worn, creating significant play within the caliper. Physical inspection of the aircraft revealed a static fracture in the rear lower portion of the brake caliper, specifically near one of the bolt holes.
Investigators also analyzed the aircraft's maintenance program. At the time, the maintenance documentation relied on various fragmented guides rather than a single, unified manual. There was no documented evidence that the required periodic inspections of the brake calipers and discs—scheduled for every 100, 500, and 1,000 flight hours—had been performed, nor was there evidence of recent brake pad replacements.
Analysis of the ground marks showed the aircraft followed an "S" shaped path. The initial failure of the left brake caused a rightward veer; subsequently, the broken caliper likely wedged against the disc, momentarily locking the wheel and pulling the aircraft to the left, before the wheel unlocked and the aircraft veered right again toward the fence. A sudden, heavy braking application shortly after landing also contributed to the structural failure of the caliper.
Findings
- The brake caliper failure was caused by excessive wear of the brake pad, which allowed for excessive lateral movement.
- This movement created stresses that led to a structural fracture in the caliper near the bolt hole.
- Deficient aircraft maintenance resulted in the excessive wear of the brake pad going undetected.
- The application of heavy braking shortly after landing contributed to the breakage of the caliper.