What happened
On 13 August 2021, a Beechcraft 95-B55 Baron, registration 2-NOVA, was conducting a private flight to Dunkeswell Aerodrome for an annual inspection. During the flight, the pilot encountered an electrical issue indicated by a warning light and a lack of current on the ammeter. After being unable to rectify the fault, the pilot diverted to Gloucester Airport.
Upon attempting to extend the landing gear, the aircraft suffered a total loss of electrical power. This loss of power rendered the radio inoperable and disabled the fuel quantity gauges, leaving the pilot unable to monitor remaining fuel levels. After being informed via mobile phone that the gear had not visibly deployed, the pilot moved to an area to attempt a manual extension. During this process, the pilot adjusted the fuel mixture to rich and the propeller pitch to fine.
As the pilot returned to Gloucester for a low-level flypast to verify the gear position, the left engine failed to respond to a power increase. The aircraft yawed significantly, but the pilot was able to use the sight of an alternate runway to perform an immediate landing.
The investigation
The AAIB examined the aircraft and found that both hinges on the right main landing gear door were broken. There was no other damage to the airframe. Investigation into the fuel status revealed that the left auxiliary tank was empty, the right auxiliary tank was low, and the main tanks were only one-quarter full. The fuel selector had been left in the auxiliary tank position.
Testing of the electrical system at Gloucester did not reveal any active faults. The investigation also looked into the pilot's use of the manual landing gear extension system, noting that the pilot had operated the system twice.
Findings
- The pilot did not attempt to switch to the alternate voltage regulator, meaning it remains unknown if the electrical fault could have been resolved.
- The pilot used the manual landing gear extension system twice, which contradicts the Pilot’s Operating Handbook (POH) instructions and may have caused the broken hinges due to potential over-travel.
- The pilot's focus on the landing gear likely led to a lack of monitoring regarding fuel consumption, especially after increasing fuel usage by setting the mixture to rich and the propeller to fine.
- The loss of electrical power prevented the monitoring of fuel levels, contributing to the near-exhaustion of the auxiliary tanks.