What happened
On October 6, 2013, a Cessna 310Q, registration PT-JCZ, was performing a private flight from Maracás, Bahia, to Salvador, Bahia. Upon landing on runway 17 at Salvador Airport (SBSV) under visual flight rules (VFR), the aircraft experienced an inadvertent retraction of the right main landing gear during the landing roll. This mechanical failure caused the aircraft to veer to the right, traveling approximately 400 meters before coming to a stop off the runway. The pilot and two passengers were uninjured, though the aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the landing gear assembly and identified advanced corrosion, including pitting, on several critical components. Specifically, the investigation focused on the bellcrank (P/N 5041001-2), the trunnion (P/N 5041000-206), and the main gear-down lock pin fastener (P/N 5041018-1). The analysis revealed that the corrosion was caused by differential aeration and the accumulation of salt deposits and industrial residues. This degradation significantly reduced the structural integrity of the bellcrank and trunnion, making them unable to withstand normal operational loads. The failure of these components subsequently caused the breakage of the down-lock pin.
Further investigation into the aircraft's environment and maintenance revealed that the aircraft was based in Salvador, an area with high salinity and industrial pollutants, and was not stored in a hangar. While the aircraft's scheduled maintenance and corrosion inspections were up to date, the investigation found that the fuselage was only washed for aesthetic purposes, leaving the landing gear bays and joints uncleaned. Additionally, while the left landing gear components were within inspection limits, they were mechanically connected to the failed right-side components.
Findings
- Corrosion in the bellcrank and trunnion weakened the structural capacity of the landing gear assembly.
- The aircraft operated in a highly corrosive environment (saline and industrial) without hangar storage.
- Maintenance practices focused on the airframe but neglected the cleaning of landing gear housings and joints.
- Maintenance procedures failed to identify the degradation of adjacent components during specific system inspections.