Summary
On March 10, 2018, a Beechcraft King Air B250 on a flight from Bolzano Airport (LIPB) to Katowice Pyrzowice Airport (EPKT) experienced a fuel leak from the left engine nacelle. The crew shut down the affected engine and diverted to Brno Airport (LKTB). During taxi with the left engine inoperative and a crosswind, the left tire sustained damage. Post-flight inspection revealed the center portion of the left engine drain valve had detached, causing the fuel leak.
Incident Details
While cruising at flight level FL310, the crew observed uneven fuel consumption, with higher consumption from the left tank compared to the right. Visual inspection confirmed a fuel leak from the left engine nacelle. After evaluating the operational situation, weather, and available airports, the crew decided to land at the nearest suitable airport in Brno. They notified air traffic control in Austria and the Czech Republic of their intention. The left engine was shut down, and the aircraft landed at Brno within maximum landing weight limits. During taxi with the inoperative left engine and a crosswind, the left tire was damaged.
Cause
The direct cause of the incident was the detachment of the center part of the left engine drain valve, which allowed fuel to leak from the left tank. A contributing factor was insufficient securing of the center part; the valve was secured by crimping the material at six points where the two components met. The crimping was deemed too weak to retain the center part.
Preventive Actions
The operator implemented two preventive measures. First, flight crews are now required to inspect the drain valves before each flight, specifically checking the security of the center part. Second, a meeting was held with the manufacturer, who reported that they are conducting research to eliminate this recurring issue (several similar cases have occurred on other aircraft of the same model). New valves will be secured using eight crimp points instead of the previous six.