What happened
On June 8, 2014, a Cessna 310Q, registration PT-JJY, departed from the Santo Antônio do Leverger Aerodrome (SWLV) in Mato Grosso, Brazil, bound for Tangará da Serra. The aircraft was operating a private flight carrying a pilot and five passengers.
During the retraction of the landing gear following takeoff, the aircraft experienced a total failure of the electrical system. The pilot observed the red gear-unlocked indicator light cycling, even though the three green lights remained illuminated. Due to the loss of electrical power, the pilot attempted to manually extend the landing gear using the hand crank. After approximately twenty minutes of flight, the pilot decided to return to the departure airfield. However, the landing was performed without the gear being properly locked in the down position, resulting in light damage to the propellers, engines, lower fuselage, and landing gear. All six occupants were unharmed.
The investigation
The investigation examined the electrical system and the aircraft's recent maintenance environment. It was noted that PT-JJY had been parked outdoors, exposed to the elements, for thirty-three days prior to the incident. Investigators found evidence of oxidation on the access door to the electrical master switch compartment, which can lead to system failures.
Regarding the manual gear extension, the pilot reported encountering resistance while using the hand crank. It is believed that the required number of turns (approximately 52) specified in the manual was not completed, leading the pilot to believe the gear was locked when it was not. Additionally, the investigation noted that the aircraft was removed from the runway before authorization from the investigation authority (SIPAER), which hindered the preservation of certain evidence.
Findings
- The total electrical failure was preceded by the cycling of the red gear indicator light.
- Oxidation on the electrical master switch compartment access door was present due to the aircraft being stored outdoors.
- The pilot failed to complete the full manual extension procedure, likely due to premature resistance felt during the cranking process.
- The electrical failure also disabled the landing gear warning horn, which normally alerts the crew when gear retraction is indicated during flap deployment or power reduction.