ATL98LA108

According to the pilot, while in cruise flight he noticed a vibration in the airplane. He stated he checked his instruments and elected to continue onto his destination. About five minutes later, he stated that oil began leaking from the front of the engine and blowing back onto his windshield, obscuring his forward vision. The airplane was damaged during the emergency landing. Examination of the wooden propeller assembly disclosed that the bolts were not properly torqued. Additionally, it was found that the crankshaft had not been modified in accordance with the manufacturers service instructions.

On August 8, 1998, about 1420 Eastern Daylight Time, a Dean R. Fellows Vans RV-6, homebuilt airplane, N245DF, collided with terrain during an emergency landing in Bainbridge, Georgia. The airplane was operated by the commercial pilot under the provisions of Title 14 CFR Part 91, and visual flight rules (VFR). Visual meteorological conditions prevailed and a VFR flight plan was filed. The pilot sustained serious injuries, and the airplane received substantial damage. The flight departed Mobile, Alabama, at 1200.

According to the pilot, while at 17,000 feet MSL, he noted the onset of a vibration in the airplane. He stated that he checked the engine instruments and noted the oil pressure, temperature and other engine instruments were stable in the normal operating range. After descending and noting the vibration was stable, the pilot elected to continue on to his destination. According to the pilot, after approximately five minutes of level flight at 3,000 feet, oil began leaking from the forward section of the engine and blowing back on the windshield. With the oil obscuring his vision, the pilot made an emergency landing in an open grass field. According to the pilot, upon landing, the landing gear contacted an undetermined object allowing the center section of fuselage to collapse.

The airplane was outfitted with a Lycoming O-360-A1A engine which can support either a constant speed propeller or, after modifications are performed, a fixed pitch propeller. In order for the airplane to be outfitted with a fixed pitch propeller, the following engine modification must be performed (as per Lycoming Service Instruction No. 1435); "When changing from a constant speed to a fixed pitch propeller, it is necessary to pierce a 1/8" to 3/16" hole in (or remove) the plug behind the oil return tube, and install an expansion plug in the front of the crankshaft. If the crankshaft incorporates a 1/8" 1102 pipe plug, it must be removed when making this conversion."

During examination of the wooden propeller assembly, severe chafing and metal transfer was noted on the mating surfaces of the propeller hub, hub spacer, spinner support, ring gear support and crank flange. Examination of the propeller mounting bolts found one of the six bolts missing, three of the five remaining bolts were broken about mid-shank and the two unbroken bolts were bent. As found, two of the unbroken bolts were partially unthreaded from the flange bushings. The front crankshaft plug was found ajar and oil was evident on the engine cowling and windshield.

A National Transportation Safety Board Form 6120.1/2 was not received from the pilot.