What happened
On June 5, 2013, a Neiva EMB-711ST, registration PT-RXY, departed from Assis, São Paulo, for a local flight. The aircraft was carrying a pilot and one passenger. Shortly after takeoff, while the pilot was attempting to retract the landing gear, the aircraft suffered a total failure of the electrical system. This failure prevented the electric reversible pump from activating the hydraulic cycle necessary to complete the retraction or to properly command the gear.
Because the retraction cycle was interrupted, the landing gear remained in an intermediate, unlocked position. The pilot subsequently decided to perform an emergency landing at the Marília Airport (SBML). The aircraft touched down with the gear unlocked, resulting in light damage to the airframe, engine, and propeller. Both occupants of the aircraft were unharmed.
The investigation
The investigation by SERIPA IV established that the aircraft had been inactive for approximately sixty days prior to the flight. Due to this inactivity, the onboard battery lacked sufficient charge to complete the engine start cycle, necessitating the use of an external power source. Although the pilot waited 15 minutes for the battery to charge after starting the engine, the investigation found that this charging process did not comply with the procedures outlined in the MS-711ST Service Manual.
Technical examinations of the electrical system revealed that the battery in PT-RXY had lost its ability to store a charge effectively. This degradation meant that the electrical load required to operate the hydraulic pump for landing gear retraction could not be sustained, leading to the system failure during the flight sequence.
Findings
- The aircraft's battery was unable to maintain sufficient charge due to improper charging procedures following a period of inactivity.
- The electrical failure occurred specifically during the landing gear retraction phase, leaving the gear in an intermediate position.
- Improper battery charging procedures and aircraft maintenance contributed to the electrical system'1s inability to support the hydraulic pump.
- Pilot judgment regarding the electrical state of the aircraft following the use of an external power source was a contributing factor.