Accident Summary
A float-equipped Cessna Caravan, registered 5N-PAN, departed Lagos (LOS) on a chartered flight to Warri with a scheduled stop at Lekki. The aircraft was airborne at 07:34 UTC and landed at Lekki at 07:42 UTC. After departing Lekki at 08:20 UTC, the aircraft was cleared to 3,500 feet by Lagos Approach and reported at TMA before continuing to Escravos Tower.
Flight History
Upon contacting Escravos Tower, the pilot requested a descent from 3,500 to 700 feet to overfly the Chevron facility at Opuekaba for an aerial inspection. After the inspection, the aircraft was cleared to 2,500 feet to resume normal flight to Warri. The pilot made an outbound turn to line up for the final approach to runway 03.
Approach and Engine Issue
At about five nautical miles DME from Warri, the pilot reduced speed to 120 knots, selected gear down, and set flaps to 15°. At three nautical miles out, the aircraft was 900 feet above the approach path and was cleared to land. The aircraft was configured for landing with flaps at 30°, and the pilot reduced speed to between 85 and 90 knots. At approximately 1.5 miles out, the aircraft was between 350 and 400 feet high, gliding with 400 lb of torque. The pilot felt a small shudder from the engine, followed by a need for power input. Advancing the throttle produced no response from the engine. The pilot quickly retracted the flaps and feathered the propeller. He then re-selected flap 30° and unfeathered the propeller, which restored the engine to full torque.
Ditching
The pilot decided to abandon the approach due to a building structure ahead near the runway threshold. He veered the airplane to the left of the approach path centerline and ditched into swampy terrain, cutting through scattered trees and shrubbery.
Probable Cause
The official investigation found the probable cause to be a fractured cotter pin that lodged itself in the orifice, causing the BOV to malfunction at a critical moment when increased power output was demanded. The engine did not completely flameout; the BOV valve's partially/fully open position allowed only idle running of the engine.