What happened
On May 25, 2001, at approximately 10:45 local time, a Rockwell Aerocomander 690, registration EC-HNH, was performing a takeoff roll from runway 05 at Valladolid Airport for a scheduled aerial photography mission. The aircraft was operated for a commercial photography flight with a crew consisting of the pilot and two photographers.
As the aircraft approached decision speed during the takeoff roll, the pilot felt a sudden jolt and noted a significant deviation toward the right side of the runway. To maintain control and prevent a complete excursion, the pilot maneuvered to keep the aircraft on the pavement, feathered the right engine, shut down the left engine, and disconnected all electrical equipment except for the battery to ensure steering control via the nose wheel.
The aircraft managed to come to a stop on the runway. During the deceleration, the occupants observed flames originating from the right main landing gear. The airport' and fire services responded immediately, managing the situation and preventing further damage. The aircraft sustained damage to the right main gear, including a disintegrated tire cover and significant wear to the tire itself, while the runway was temporarily closed for three hours for cleaning.
The investigation
The investigation focused on the mechanical failure of the right main landing gear and the subsequent fire. Investigators examined the condition of all tires on the EC-HNH, finding that the left main tire and the nose tire were in good condition with no signs of abnormal wear or aging. However, the right main tire showed extreme degradation; the tire tread had been worn down to nearly half its original diameter, and the tire cover had fragmented into small pieces.
Evidence from the tire rim indicated that the aircraft had experienced lateral movement toward the right. The investigation also found that the hydraulic line supplying the right brake assembly had become detached from its supports, resulting in a fluid leak. Investigators analyzed whether the fire was caused by the ignition of this leaking hydraulic fluid upon contact with the hot, friction-heated surfaces of the tire and pavement.
Findings
- The right main tire lost air pressure during the takeoff roll, causing the aircraft to tilt and deviate from the runway centerline.
- The loss of pressure caused the tire to run on its edges, leading to the disintegration of the tire cover and extreme abrasive wear on the tire carcass.
- A manufacturing defect in the tread is considered the most probable cause of the initial tire failure, as no sudden burst or irregular sound was reported by the crew.
- The observed fire was likely caused by the leakage of hydraulic fluid onto the hot, friction-heated components of the landing gear during the high-speed deceleration.
- The pilot's decisive actions prevented a more serious runway excursion.