What happened
On May 1, 2003, an AMT-200 aircraft, registration PP-KDV, was performing scenic flights at the Nobres Aerodrome in Mato Grosso, Brazil. During the third takeoff roll of the day, the left main landing gear began to retract unexpectedly, causing the aircraft to yaw sharply to the left. The pilot attempted to abort the takeoff by reducing engine power and applying brakes; however, the sudden imbalance caused the right main gear and the nose gear to twist and break. The structural stress from the failure of the right side subsequently caused the partially retracted left gear to collapse as well. The aircraft swung 180 degrees on the runway, eventually coming to a stop with the right wing off the paved surface. Both the pilot and the passenger escaped the incident uninjured.
The investigation
CENIPA investigators examined the aircraft's maintenance records and the physical condition of the landing gear system. The investigation focused on why the left gear moved from its locked-down position. While the aircraft's maintenance logs were up to date and the pilot was fully qualified, investigators analyzed several hypotheses. One possibility involved a mechanical adjustment issue with the upper semi-strut stop screw. Another possibility considered whether the pilot failed to verify the gear lever position during the pre-flight inspection, or if the passenger had inadvertently moved the lever. The investigation also noted that the aircraft, owned by the Brazilian Department of Civil Aviation (DAC), was being used for scenic flights, which was an irregular use of aircraft intended for flight instruction.
Findings
- The primary cause of the accident was the unintended retraction of the left main landing gear during the takeoff roll.
- The dirt runway at Nobres was in poor condition, featuring holes, stones, and vegetation, which likely caused vibrations and jolts that contributed to the gear unlocking.
- The aircraft suffered significant damage, including an unrecoverable propeller and severe damage to the landing gear, engine, fuselage, and wings.
- The use of DAC-owned aircraft for scenic passenger flights was found to be in violation of existing regulations (RBHA 140).
- Potential contributing factors included possible improper maintenance of the gear stop screw, a failure to verify the gear lever position, or accidental interference by the passenger.