What happened
On January 15, 2022, an Air Tractor AT-502B, registration PR-SRL, was performing a local agricultural spraying flight from the Serra Branca Agrícola Aerodrome in Uruçuí, Piauí. During the initial stages of the takeoff roll, the right main landing gear spring failed. This mechanical failure caused the aircraft to yaw sharply to the right, eventually coming to a stop on the runway approximately 90 meters from the takeoff threshold. The aircraft sustained substantial damage, specifically affecting the propeller assembly, the right wing, the flap, and the aileron. The pilot was uninjured.
The investigation
The investigation by CENIPA focused on the structural failure of the landing gear component. While the aircraft was operating 110 kg above its maximum takeoff weight, investigators could not establish a direct link between the weight imbalance and the failure. The right main landing gear spring had been in service for 610 hours since its last replacement.
Although the component had not reached its service life limit, investigators noted that the aircraft's maintenance records indicated a discrepancy in how service life was calculated. The operator had been applying a "light service" life limit of 3,000 hours based on Service Letter #104, whereas the actual nature of the agricultural operations (unpaved/irregular surfaces) suggested a "medium service" classification, which would reduce the allowable life to 2,000 hours.
Visual inspection of the failed spring revealed pre-existing cracks and corrosion in the collapsed region. While the component was well within the 2,000-hour limit, the presence of corrosion and cracks suggested that the structural integrity had been compromised by environmental factors or undetected fatigue. The specific root cause of the rupture could not be definitively determined because the component was not available for laboratory analysis.
Findings
- The failure of the right main landing gear spring was the primary event leading to the loss of directional control.
- Pre-existing corrosion and cracks were visible on the failed component.
- The aircraft was operating outside of its established weight and balance limits.
- There was an inconsistency in the maintenance program regarding the application of service life limits based on the type of operational service (light vs. medium).
- Maintenance and management supervision factors remained undetermined.