What happened
On December 3, 2013, a Beechcraft C90A, registration PR-MZP, was performing a local flight from Bacacheri Aerodrome (SBBI) in Paraná, Brazil, for systems verification. The aircraft was carrying a pilot and two passengers.
During the return to the airfield, while entering the traffic pattern, the pilot extended the landing gear; however, the indicator light for the left main landing gear failed to show it was locked down. Despite cycling the gear up and down, the indication remained unconfirmed. Due to the runway dimensions at the departure airfield, the pilot elected to divert to Afonso Pena Aerodrome (SBCT) in Curitiba.
Upon crossing runway 29, the pilot shut down the engines, feathered the propellers, and turned off the electrical system. After the aircraft came to a complete stop, the battery was reconnected to communicate with the control tower. Following this, the left main landing gear retracted, causing the left propeller blade and the left wing to strike the ground. The aircraft sustained substantial damage to the left propeller, left engine, left landing gear, fuselage, and left wing. All three occupants were uninjured.
The investigation
CENIPA's investigation focused on why the landing gear failed to lock and why it retracted while the aircraft was stationary. The aircraft had undergone landing gear maintenance six days prior to the flight.
Investigators examined the emergency landing gear manual extension procedures. They found that the pilot had not correctly followed the required steps: the Landing Gear Relay Circuit Breaker was found in the pressed position, whereas instructions dictate it should be pulled and remain in that position. Additionally, the Alternate Extension Handle was found in the lowered position, rather than at the top of its travel, and had been moved to the level of the retaining clip, which results in a loss of pressure.
Findings
- The pilot failed to follow established emergency procedures for manual gear extension.
- The left main landing gear retracted while the aircraft was on the ground.
- The cause of the initial failure of the left main gear indicator light could not be determined.