What happened
On 18 August 2003, a Fairchild Boling and Mk IV T, registration G-BPIV, was performing aerial work during a transit from Somerley Park back to Duxford, Cambridgeshire. During the flight, the pilot observed inconsistent fuel gauge readings between the left and right tanks, noting that the total fuel remaining was lower than anticipated. Believing the discrepancy to be a gauge error, the pilot proceeded toward the destination.
As the aircraft entered the left base leg for Runway 24, the right engine began to surge. The pilot initially decided to execute an emergency landing in a field east of the runway. However, as flaps were extended and power was reduced, the right engine began to regain power, prompting a decision to attempt a landing on the active runway. During this approach, the right engine failed completely. While attempting to maintain control with the left engine, the pilot had to reduce power to manage a developing roll. The aircraft struck an embankment short of the runway threshold, sliding up the slope and rotating 90 degrees before coming to a halt. The two crew members sustained minor injuries.
The investigation
Investigators examined the fuel system and engine performance to determine the cause of the power loss. The analysis established that the right engine had failed because of fuel starvation. While the pilot had calculated fuel requirements based on a 'weak' mixture setting, the flight was actually conducted using a 'normal' mixture setting, for which specific consumption rates were not known. Additionally, although the fuel cross-feed system was engaged, it was found to be unable to supply fuel from the left tank to the right engine during the left-hand turn onto the final approach.
Findings
- The right engine failed due to a lack of sufficient fuel supply.
- Fuel consumption was higher than the pilot had calculated because the aircraft was operated on a 'normal' mixture rather than the 'weak' mixture used for the initial calculations.
- The fuel cross-feed mechanism failed to provide adequate fuel from the left tank to the right engine during the turn onto finals.
- The investigation could not determine why fuel consumption was asymmetrical between the two engines.