What happened
On September 12, 2012, an Embraag EMB-810C, registration PT-RCA, was conducting a private passenger flight from Fazenda Ribeirão, PI, to Fazenda São Gabriel, MA. During the approach to the destination airport (SITJ), the pilot encountered a failure in the auxiliary landing gear, which failed to extend. After unsuccessful attempts to deploy the gear using the emergency system, the pilot diverted to the Balsas Aerodrome (SNBS) in Maranhão, seeking a longer runway and better emergency services, despite the airport being closed for operations per NOTAM.
To mitigate risks, the pilot performed a low pass over the runway to consume fuel before executing a landing with the landing gear and flaps retracted. The aircraft sustained substantial damage to the fuselage, propellers, and engines, but all four occupants remained uninjured.
The investigation
CENIPA investigators examined the auxiliary landing gear compartment and discovered a cloth bag, typically used for automotive maintenance, lodged within the gear structure. The presence of this material caused the displacement of an oil hose connection (elbow) near the auxiliary gear actuator. This displacement forced the hose into the actuator, creating friction against the actuator's piston and physically preventing the gear from extending.
Additionally, investigators found hair within the hydraulic lines. Taxonomic analysis identified the hair as belonging to a marsupial, specifically a water opossum (*Chironectes minimus*). It is believed that the cloth bag was located near dense vegetation used by an agricultural company and was moved into the gear compartment by the animal while the aircraft was parked in an open area for several days. Laboratory testing at the Institute of Aeronautics and Space (IAE) confirmed that the actuator cylinder had undergone plastic deformation due to the overload caused by the obstruction.
Findings
- The primary cause of the landing gear failure was the obstruction of the actuator piston by a cloth bag and displaced hydraulic components.
- The presence of foreign object debris (FOD) was facilitated by wildlife (a marsupial) moving items into the aircraft compartment during ground operations.
- The pilot's pre-flight inspections failed to detect the obstruction because the material was located in a difficult-to-access area of the gear nacelle.
- The decision to divert to a closed airfield was made to ensure access to longer runway length and emergency medical/fire support.