What happened
On May 23, 2013, an Embraer EMB-721C, registration PT-EFI, operated by Tropic Air Taxi Aereo Ltda, was performing a ferry flight from Fazenda Tauá to Porto Seguro, Brazil. During the approach to Porto Seguro Airport (SBPS), the pilot attempted to configure the aircraft for landing but found that the landing gear failed to extend via the normal system. After three unsuccessful attempts to cycle the gear using the normal system, the pilot activated the emergency extension procedure. This procedure successfully locked the main landing gear but failed to lock the nose gear.
Upon touchdown on runway 10, the nose gear remained unsecured and retracted immediately after contact with the runway. This caused the propeller to strike the ground four times. The pilot had shut down the engine moments before touchdown to mitigate impact. The aircraft came to a stop approximately 150 meters after the initial contact, before reaching the midpoint of the runway. The pilot and the single passenger on board were uninjured.
The investigation
CENIPA investigators examined the aircraft and found that while the electrical system was intact and the landing gear circuit breakers were armed, the reversible electric pump was non-functional, preventing hydraulic pressurization. The investigation revealed that the aircraft had been subjected to frequent washing due to operations in highly corrosive environments and on unpaved strips.
Investigators found significant corrosion throughout the fuselage and specifically within the main and nose landing gear housings. Furthermore, the landing gear pivot points were inadequately lubricated. The accumulation of salinity and fine sand in the nose gear housing likely created excessive friction, preventing the gear from completing its extension cycle even with the assistance of the emergency gravity-drop system.