What happened
On April 2, 2018, a Piper PA-25-260 was performing agricultural spraying operations near Lucas do Rio Verde, Mato Grosso. The aircraft departed from a landing strip at Fazenda Santa Lúcia for a routine mission. During the fourth application pass, immediately after completing a repositioning turn, the pilot experienced a sudden loss of lift on the right wing. The aircraft failed to respond to recovery attempts and struck the ground. The initial impact occurred on the right wing, causing it to detach from the fuselage, followed by a second impact as the aircraft continued along its flight path. The aircraft sustained substantial damage, and the pilot sustained serious injuries.
The investigation
CENIPA investigators examined the wreckage and the aircraft' and maintenance records. While the pilot reported a sensation of an impact with the landing gear during an earlier pass, investigators found no evidence of any external collision with objects or wildlife. The aircraft's maintenance logs showed that recent inspections for corrosion and cracks had been performed in accordance with manufacturer service bulletins.
Technical analysis of the right wing spar, conducted by the Department of Aerospace Science and Technology (DCTA), revealed characteristic "beach marks" on the fracture surface. These marks are indicative of a material fatigue fracture. Investigators also noted that while standard inspections for corrosion and cracks were up to date, the maintenance documentation lacked specific instructions for detecting internal fatigue processes within the wing structure. Furthermore, it was noted that agricultural aircraft often operate under aerodynamic loads that may exceed the standard flight envelope, potentially accelerating structural degradation.
Findings
- The right wing spar suffered a fracture due to material fatigue.
- The structural failure likely altered the aircraft's aerodynamic characteristics, leading to the loss of control.
- The pilot was properly qualified, and the aircraft was airworthy and within weight and balance limits at the time of departure.
- Existing maintenance protocols focused on detecting surface corrosion and cracks but did not specifically address the identification of internal fatigue processes.