What happened
On November 30, 2002, a Beechcraft A-36, registration PT-OLS, was performing a flight from Nova Mutum to Cuiabá, Mato Grosso. The aircraft had previously flown from Brasília to Lucas do Rio Verde and then to Nova Mutum without any refueling stops.
During the final approach to runway 17 at Cuiabá, the engine failed while the pilot was executing a turn to align with the runway. Faced with the loss of power, the pilot performed an emergency landing on a public avenue in Várzea Grande, approximately 1.3 km from the aerodrome. During the landing roll, the aircraft's right wing collided with a utility pole, which caused the wing and the right landing gear to separate from the fuselage. The aircraft sustained severe damage to the propeller, engine, landing gear, wings, and fuel and hydraulic systems. The pilot escaped uninjured, while the passenger sustained minor injuries.
The investigation
The CENIPA investigation focused on the cause of the engine failure and the decision-making process leading to the fuel exhaustion. Technical examinations of the engine and fuel systems conducted by a maintenance workshop found no mechanical failures or leaks that would justify a sudden loss of power. However, investigators found no fuel present in the fuel system lines.
While some spark plugs showed deficient performance and one cylinder exhibited excessive carbonization, these factors were not considered sufficient to cause the engine to stop. The investigation noted that the A-3 and similar models lack a fuel pickup's 'pescador' (sump/collector) mechanism, meaning fuel levels are not stabilized during maneuvers. The investigation established that the engine failure was caused by an interruption in fuel flow due to insufficient fuel levels.
Findings
- Fuel Exhaustion: The engine failure was caused by a lack of fuel in the system, triggered by the fuel level becoming too low to maintain flow during a flight maneuver.
- Inadequate Flight Planning: The pilot failed to plan for sufficient fuel reserves, neglecting to refuel during previous flight legs and failing to account for potential deviations due to weather or headwinds.
- Pilot Overconfidence: The pilot's excessive confidence influenced his decision-making, leading to a disregard for regulatory fuel requirements (RBHA 91.151) and an inappropriate assessment of the risks associated with low fuel levels.
- Aircraft Design Limitation: The absence of a fuel collector/pickup system in this aircraft model made the engine highly susceptible to fuel starvation during turns when fuel levels are low.