What happened
On December 8, 2010, at approximately 15:40 UTC, a Cessna A188B, registration PR-FFG, was performing an agricultural spraying operation departing from the Aeroclube de Eldorado (SIXE) in Eldorado do Sul, Rio Grande do Sul. The aircraft was carrying 600kg of urea in the hopper and 50 liters of AvGas in each wing, bringing the total takeoff weight to 1,790kg, which was within the manufacturer's maximum takeoff weight limit of 1,905kg.
During the takeoff roll, the right main landing gear collapsed. This caused the aircraft to veer off the runway and come to a stop in a grassy area of the aerodrome. The pilot was uninjured, but the aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the wreckage and identified that a mounting bolt for the right main landing gear had failed. The component was sent to the Department of Aerospace Science and Technology (DCTA) for laboratory analysis. The investigation established that the bolt failed due to an overload caused by bending stresses that exceeded the material's strength limits.
According to the manufacturer's maintenance schedule, this specific bolt was due for replacement every 1,000 flight hours or 24 months, whichever occurred first. The scheduled replacement date was January 12, 2011, meaning the part was still within its service life at the time of the accident. However, investigators noted that the aircraft, manufactured in 1979, was used for agricultural operations on unprepared runways, which may have contributed to the structural stress.
Findings
- The failure of the right main landing gear was caused by the breakage of a mounting bolt due to bending overload.
- The aircraft was operating within its approved weight and balance limits at the time of the incident.
- The operator's lack of operational oversight meant that flight planning for the agricultural mission was conducted by the pilot without company supervision.
- The use of unprepared runways for agricultural operations likely contributed to the fatigue or stress on the landing gear components.