What happened
On March 6, 2007, at approximately 23:15 UTC, an Embraer 820-C, registration PT-RGV, was performing a cargo transport flight from Vitória da Conquista to Salvador, Bahia. The flight, operated by Aerotaxi Abaeté Ltda, was being flown by a crew of two under VFR conditions following an ILS approach to runway 10 at Salvador Airport (SBSV).
The aircraft touched down approximately 50 meters before the 1000ft marker, slightly to the right of the runway centerline. During the landing roll, approximately 180 meters after touchdown, the left main landing gear retracted. This caused the left wing and propeller to strike the ground, inducing a strong yaw that sent the aircraft off the left side of the runway. The aircraft came to a stop three meters from the runway edge. The two crew members on board were uninjured, but the aircraft sustained substantial damage to the engine, propeller, left aileron, left flap, and left wingtip.
The investigation
CENIPA investigators examined the mechanical state of the landing gear and the maintenance history of the aircraft. Although the landing gear locks were found in the engaged position after the incident, investigators discovered that the tension of the landing gear lock hook spring was below the manufacturer's minimum specification. The service manual required a minimum tension of 3.2 kgf (7 lbs), but the measured tension was only 2.75 kgf.
The investigation also reviewed the flight path, noting that the landing was slightly off-center. The investigators analyzed whether the pilot's use of rudder pedals to correct the aircraft's trajectory contributed to the gear retraction. It was determined that the aircraft had undergone a 200-hour inspection 83 hours and 40 minutes prior to the accident, which included a check of this specific spring tension.
Findings
- The primary cause of the gear retraction was the insufficient tension of the landing gear lock hook spring, which allowed the lock to disengage under stress.
- The use of large rudder inputs to correct the aircraft's off-center position likely subjected the landing gear assembly to increased forces, triggering the release.
- Maintenance deficiencies were identified, as the spring tension was below the required limit.
- Inadequate management supervision regarding maintenance oversight contributed to the occurrence.