Accident Overview
On April 27, 2015, at approximately 1525 central daylight time, a Diamond Aircraft Industries DA20-C1, registration N248ME, was substantially damaged during a forced landing while attempting to depart from Sylacauga Municipal Airport (SCD), Sylacauga, Alabama. The student pilot was not injured. Visual meteorological conditions prevailed, and a company flight plan was filed for the instructional flight, which was destined for Newnan Coweta County Airport (CCO), Newnan, Georgia. The flight was conducted under 14 Code of Federal Regulations Part 91.
Flight Sequence
The purpose of the flight was for the student pilot to complete a solo cross country flight. Earlier that morning, the student met with his flight instructor to review the flight plan and perform a preflight inspection of the airplane. They topped off the fuel tank, and the student departed from the airplane's home base at CCO en route to SCD. The flight instructor departed CCO in another airplane and remained in radio contact throughout the uneventful flight.
Prior to departing on the return leg, the student performed another preflight inspection and engine runup check, then departed for CCO. He initiated a takeoff from runway 9. At about 300 feet above ground level (agl), he noted a "bumpy" engine feel and degraded climb performance. He confirmed the mixture control was fully forward, the fuel pump was on, and the throttle was fully open. The student informed his flight instructor via radio. The instructor advised him to again ensure the mixture was fully rich and the fuel pump was on. Engine rpm then decreased from 2,300 to 2,000. The instructor told the student to return to the airport and land.
The student climbed to about 900 ft agl and entered the downwind leg of the traffic pattern, noting a helicopter near the approach end of runway 9. Near mid-field on downwind, he reduced engine power to 1,800 rpm and configured for landing. On final approach, the airplane was still "too high" for a normal landing. The instructor advised the student to abort the landing and initiate a go-around. The student positioned the throttle fully forward, retracted the flaps to takeoff position, and attempted to climb. After hearing the stall warning, he decreased the pitch attitude and performed a forced landing to a grassy area ahead. During the landing, the right wing struck a utility line. The pilot stated "my landing was heavy," resulting in a collapsed nose landing gear and substantial damage to the firewall and forward fuselage.
Engine Examination
A Federal Aviation Administration (FAA) inspector examined the airplane at the accident site and supervised a test run of the engine. The engine started normally but was run at low power due to propeller damage; the test was discontinued. The engine and airframe were retained for further examination.
A subsequent test run included running the engine to 1,900 rpm, which showed normal fuel flow and pressure. As throttle increased, rpm dropped and the engine ran rough with no rpm increase. The throttle body/fuel metering unit was removed and tested on a flow bench; fuel pump pressure at 2,800 rpm was 37.46 pounds per square inch gauge (PSIG), while manufacturer's specification was 47.80-48.00 PSIG. A test throttle body/fuel metering unit was installed, and a test run to about 2,800 rpm for 15-20 minutes achieved fuel pressures within specification. The original unit was reinstalled; a test run to 2,100 rpm was achieved before the engine ran rough and backfired with no rpm increase. The original unit was again removed and bench-tested, resulting in fuel pressure below specification throughout all throttle settings. Another test produced the same conclusion.
The throttle body/fuel metering unit was sent to the NTSB Materials Laboratory for detailed examination. Inspection of its components revealed no issues with the shaft and fuel metering disk cam profile. Examination of the tapered knurls on the mixture control lever showed several sets of knurl impression marks, consistent with the lever being repositioned several times. The surface finish of the tapered area was patinated brown, with no indication of lever sliding relative to the shaft. The tapered knurls on the shaft exhibited deformed crowns consistent with compressive deformation. The shaft had nicks, burrs, and raised areas along its length, as well as marks consistent with rework and aggressive cleaning or sanding.
Aircraft and Pilot Information
According to FAA records, the airplane was issued an airworthiness certificate on April 19, 2004, and registered to AAF Incorporated in April 2015. It was equipped with a Continental Motors Inc. IO-240-B17B, 125-hp engine and a Sensenich W69EK7-63 fixed pitch propeller. The most recent annual inspection was performed on February 9, 2015, at a total time of 3,866.8 hours. Engine maintenance records showed that the fuel pump, throttle body/fuel metering unit, and fuel manifold were overhauled on January 9, 2014, and installed on the accident airplane in July 2014.
The pilot held a student pilot certificate. His most recent medical certificate was issued on February 13, 2015, at which time he reported 54 hours of flight experience, all in the DA20-C1.