Accident Overview
On February 8, 2015, about 1407 eastern standard time, an American AA-1, registered N6116L, collided with trees and then the ground during a forced landing shortly after takeoff near Fort Meade, Maryland. The commercial-rated pilot and one passenger sustained serious injuries, and the airplane was substantially damaged. The aircraft was co-owned by three private individuals and operated under Part 91 as a personal local flight. Visual meteorological conditions prevailed, and a Washington, D.C., SFRA flight plan was filed.
Flight Details
The pilot reported that the purpose of the flight was to perform touch-and-go landings to verify that previous repairs to address engine roughness had eliminated the problem. A preflight inspection showed no contamination in the fuel samples from each tank, which had 3/4 capacity. After engine start, the pilot taxied to runway 28 and performed a full-power engine run-up lasting 2 to 2.5 minutes, during which magneto drops were equally 75 rpm and no roughness was noted.
With no flaps extended, the auxiliary fuel pump on, and the fuel selector on the right tank, the pilot initiated takeoff. During the takeoff roll at 60 to 70 mph, he observed full dynamic redline rpm of 2,500. The airplane became airborne about midpoint of the runway, climbing at 80 mph (Vx). About 30 to 40 seconds after full power application, at about 250 feet above ground level, he noted an abrupt partial loss of engine power. The engine rpm dropped from 2,500 to 1,500, then to 1,900. He cycled the magneto switch from both to right and back, applied carburetor heat, and turned off the auxiliary fuel pump, but none of these actions restored power. He did not move the fuel selector valve. While flying between 62 and 65 mph, he flared at tree top height. The airplane came to rest inverted, and the pilot exited from the right side.
Post-Accident Inspection
Following recovery, the Lycoming O-235-L2C engine (serial number L-9916-15) was inspected by a representative of the engine manufacturer under FAA oversight. The engine was equipped with solid tappets. The data plate had ".005" stamped next to the original ".010" stamp for tappet clearance. Crankshaft, camshaft, and valve train continuity was confirmed during hand rotation of the propeller, and thumb suction and compression were noted in each cylinder. Steel pushrods were installed at all cylinders. Dry tappet clearance was checked with a feeler gauge; the smallest thickness of 0.002 inch could not be inserted at any valve, and a smaller gauge was not available, so actual clearance was not determined. Borescope inspection revealed pitting and scuffing of the No. 3 cylinder, and its removal showed scuffing on the piston side. Inspection of fuel metering, ignition, and exhaust systems found no evidence of preimpact failure or malfunction.
Maintenance History
The pilot, a part owner, reported that about the end of September, engine roughness was felt during a flight in the traffic pattern. Maintenance personnel changed spark plugs, and later replaced the ignition harness after further intermittent roughness. About one or two weeks later, roughness recurred during a full-power run-up, leading to replacement of internal components of both magnetos on January 9, 2015. The engine logbook showed an overhaul on June 21, 1999, at 2,082.2 hours total time, and installation on July 10, 2000. Only one entry of tappet clearance adjustment was recorded, dated July 20, 2007, at 136.2 hours since major overhaul. An entry dated July 16, 2014, indicated removal and reinstallation of the No. 3 cylinder due to no compression. At the time of the accident, engine time since major overhaul was approximately 360 hours, about 224 hours since the last valve clearance check.