What happened
On March 10, 2007, a Columbia 350, registration N1271B, was performing a private flight from Cuatro Vientos Airport to Casarrubios Aerodrome. During the landing roll on runway 08, after the pilot applied the brakes, the aircraft suddenly veered sharply to the right. The pilot attempted to correct the deviation using differential braking, but the aircraft began to oscillate violently between left and right turns. This intense vibration continued for approximately 260 meters, with the aircraft's tracks on the runway showing a "hopping" pattern as the wheels alternately lost and regained stable contact. The aircraft eventually came to a stop near the end of the runway. The incident resulted in substantial damage to the aircraft, including a large crack and deformation in the tail fuselage and the loss of a right main gear wheel fairing. The pilot was uninjured.
The investigation
Investigators examined the aircraft's structural integrity and maintenance history. Inspections of the landing gear revealed that the copper alloy bushings, which are intended to support nonaxial loads and prevent wear, had become dislodged from their housings in both the left and right main gear legs. The investigation also found that the tire pressures in the main gear were significantly below nominal levels.
Regarding the aircraft's manufacturing history, it was discovered that the manufacturer had changed the adhesive used to secure these bushings from Loctite 675 to Loctite 638 without updating the owner's maintenance documentation. The investigation noted that the separation between the bonded elements in the incident aircraft exceeded the requirements for the 638 adhesive. Furthermore, the investigation found that the aircraft's tail area had previously undergone composite repairs following hail damage, though it could not be definitively determined if this contributed to the structural fracture.
Findings
- The primary cause of the incident was large vibrations during the landing roll resulting from the landing gear bushings being dislodged from their housing.
- The use of differential braking by the pilot to correct the initial veer likely increased the duration and intensity of the vibrations.
- Low tire pressure in the main landing gear may have contributed to decreased braking efficiency and a prolonged landing roll.
- The manufacturer's use of an unrecorded change in adhesive (Loctite 638) meant the installation did not meet the necessary separation tolerances for that specific chemical agent.
- The aircraft's tail structure suffered a fracture at the junction of the antenna bulkhead and the vertical shear web.