This January 2010 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Beech B60 Injuries: 2 Fatal. Location: Madison, Ala. Aircraft damage: Destroyed.
What reportedly happened: Approximately 15 minutes after takeoff and at an altitude of 6,000 feet, the right engine experienced catastrophic engine failure. The nearest suitable airport for landing was about 10 miles away. However, the pilot elected to return to the departure airport, which was 30 miles away. He reported that he was not able to maintain altitude. The airplane crashed and burned approximately three miles from the intended airport.
The post-accident investigation discovered a 5 1/2- by 6-inch hole in the top right portion of the crankcase. It was determined that the No. 2 cylinder of the right engine had separated from the crankcase in flight. Two No. 2 cylinder studs were found to have fatigue fractures consistent with insufficient preload on their respective bolts. A fatigue fracture was found on a portion of the right side of the crankcase, mostly perpendicular to the threaded bore of the cylinder stud. The rear top 3/8-inch and the front top 1/2-inch cylinder hold-down studs for the No. 2 cylinder exceeded the manufacturer’s specified length from the case deck by .085 and .111 inches, respectively.
The airplane had been operated for about 50 hours since its most recent annual inspection, which was performed about eight months prior the accident. The right engine had been operated for about 1,425 hours since it was overhauled, and about 455 hours since the No. 2 cylinder was removed for the replacement of six cylinder studs.
It was not clear why the pilot was unable to maintain altitude after the right engine failure, however, the airplane was easily capable of reaching the closer airport had the pilot elected not to return to his departure airport.
Probable cause: The pilot’s failure to divert to the nearest suitable airport following a total loss of power in the right engine during cruise flight. Contributing to the accident was the total loss of power in the right engine due to separation of its No. 2 cylinder as a result of fatigue cracks.
For more information: NTSB.gov. NTSB Identification: ERA10FA115
