What happened
On August 19, 2011, an Embraer EMB-711 operated by Heiss Táxi Aéreo Ltda. departed Soure (SNSW) for Breves (SNVS) in the state of Pará, Brazil. The flight, which involved the transport of bank mail and two passengers, proceeded normally until the aircraft arrived at the intermediate stop in Soure. Upon arrival, the pilot kept the engine running while performing mail delivery tasks.
During the subsequent leg from Soure to Breves (SBJC), the pilot attempted to retract the landing gear after takeoff, but the gear failed to retract completely. This was caused by a failure in the electrical system. The pilot activated the emergency gear extension procedure and diverted to the alternative airport in Belém. Because the aircraft's radio was non-functional due to the electrical failure, the pilot contacted the Belém tower via mobile phone.
Upon landing at Belém, the main landing gear partially retracted during the landing roll. The aircraft traveled approximately 250 meters before veering off the left side of the runway. The three occupants of the aircraft escaped without injury, though the aircraft sustained light damage.
The investigation
CENIPA investigators determined that a faulty transistor in the voltage regulator caused a failure in the alternator's ability to rectify alternating current. This prevented the alternator from generating the required 14 volts, meaning the aircraft's electrical load was being supplied solely by the internal battery. As the battery became depleted, the pilot lost the ability to operate the landing gear via the normal electrical system.
Investigators also found that because the pilot did not shut down the engine during the mail delivery stop in Soure, the required ground checklist—specifically the verification of the alarm lights—was not performed. Consequently, the pilot did not notice the alternator failure light (ALT) had illuminated on the instrument panel.
Furthermore, because the battery was exhausted, the pilot could not use the cockpit indicator lights to confirm that the emergency gear extension had successfully locked the gear in the down position. As a result, the pilot did not perform the supplementary maneuvers, such as using the rudder to induce gear locking, which could have prevented the gear from retracting during the landing roll.
Findings
- A defective component in the voltage regulator caused the alternator to fail to charge the battery.
- The aircraft's electrical system was running entirely on battery power, which eventually reached a state of exhaustion.
- Failure to perform ground checks during the intermediate stop prevented the early detection of the alternator failure.
- The pilot's decision-making regarding the emergency gear extension procedure contributed to the gear not being properly locked.