History of Flight
On January 7, 2016, at about 1540 central standard time, an experimental amateur-built Eros 1600 airplane, registration N508AH, collided with terrain following a total loss of engine power near Lebanon, Tennessee. The private pilot was fatally injured, and the airplane was substantially damaged. The personal flight was conducted under Part 91 of the Federal Aviation Regulations. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which originated from Lebanon Municipal Airport (M54).
GPS data indicated that the airplane departed M54 at 1515 and conducted an approximate 20-minute local flight. It then returned to the airport, landed, and initiated a second takeoff. A witness, who was a pilot, reported that the airplane made a normal takeoff, then began a right turn at low altitude. The airplane "abruptly" turned left about 100 ft above ground level (agl) "as if it was trying to return to the airport." It subsequently rotated "sharply" to the left and descended to ground contact. Other witnesses reported hearing the airplane "circle" at low altitude, followed by a loss of engine power.
A friend of the pilot stated that the pilot had been performing maintenance on the engine because it was "intermittently missing." The pilot had installed a new ignition coil and reinstalled the engine on the day of the accident. The flight was intended as a test to determine if the engine problem had been resolved.
Personnel Information
The pilot held a private pilot certificate with a rating for airplane single-engine land and a repairman experimental aircraft builder certificate issued May 15, 2014. He held a third-class FAA medical certificate issued August 24, 2006, with no limitations. According to logbooks, the pilot had about 259 total flight hours, including 8.9 hours in the accident airplane. His most recent flight review was completed on May 27, 2014.
Aircraft Information
The experimental amateur-built airplane was owned by the pilot and issued an airworthiness certificate on May 15, 2014. It was equipped with a two-cylinder Rotax 532, 64-horsepower engine installed on October 7, 2015. Maintenance logbooks showed the airplane had a total time of about 14 hours. The most recent condition inspection was performed by the pilot on October 7, 2015, at 1.6 hours. A whiteboard in the pilot's hangar indicated a fuel/oil ratio of 40:1. According to the pilot's son, the engine was previously installed on a snowmobile.
The airplane operating handbook specified that the design was for a 41-hp Rotax 447 engine, with flaps-up stall speed of 34 mph and flaps-extended stall speed of 29 mph. The emergency procedures noted that engine failure was a likely occurrence given the uncertified engine, and recommended establishing a glide at minimum airspeed of 45 calibrated airspeed, selecting a landing spot, and performing a normal power-off landing with a minimum flare airspeed of 40 mph.
Meteorological Information
Weather recorded at 1553 at Smyrna Airport (MQY), about 14 nautical miles southwest of the accident site, included wind from 120° at 4 knots, visibility 10 statute miles, broken cloud layers at 3,500 ft and 4,400 ft agl, temperature 13°C, dew point 8°C, and altimeter setting of 30.02 inches of mercury.
Wreckage and Impact Information
The airplane struck terrain and came to rest inverted on a westerly heading next to a residence about 850 ft from the departure end of runway 04. All components were located near the wreckage. Flight control continuity was confirmed from cockpit to all surfaces.
Rotating the propeller by hand confirmed engine continuity. Spark plugs were removed; the aft cylinder spark plug was dark grey with normal wear, while the front plug was white. Thumb compression was obtained on the aft cylinder but not on the front cylinder. Examination after removing the top engine case revealed a hole about 1 cm in diameter in the center of the front cylinder piston. The aft cylinder had carbon deposits and oil residue. Connecting rod bearings were loose in both cylinders. The exhaust y-pipe showed carbon deposits in the aft pipe; the front cylinder exhaust gas temperature probe was white and the aft probe grey.
Both carburetors were impact separated but attached via cables. Disassembly revealed jet needles on the third clip from the top under white retaining cups, and main and pilot jets were free of debris. Both carburetor rubber adaptors had cracks and evidence of material degradation; the front adaptor was partially fractured. The rotary valve plate cover indicated the intake port was fully open when the piston was at top dead center.
The ignition coil remained attached to the engine but a wire was separated. Testing confirmed ignition continuity from flywheel to spark plugs during propeller rotation.
Additional Information
The engine operator's manual specified a 50:1 fuel-to-oil mixing ratio, warning that too much oil causes carbon deposits. White spark plug electrodes indicated a low heat range or excessively lean calibration. The engine repair manual stated the carburetor must be checked every 25 hours, and the adaptor should be inspected for cracks or damage, as any damage could alter pressure conditions and lead to engine damage.
The Pilot's Handbook of Aeronautical Knowledge described detonation as uncontrolled explosive ignition causing high temperatures and pressures that can lead to piston, cylinder, or valve failure. Preignition occurs when fuel ignites before normal ignition, often from hot spots. An engine manufacturer's presentation noted that damage to the front piston was consistent with piston dome detonation, possibly from pre-ignition leading to detonation.
A pamphlet by the FAA Safety Team stated that startle responses during unexpected powerplant failure on takeoff or initial climb can contribute to loss of control, and continuing straight ahead may improve survival probability compared to turning back.
Medical and Pathological Information
An autopsy by the Office of the Medical Examiner in Nashville, Tennessee, determined the pilot died from multiple blunt force injuries. Toxicological testing by the FAA Bioaeronautical Sciences Research Laboratory detected no carbon monoxide or ethanol. Sitagliptin, a medication for Type 2 diabetes, was found in liver and blood; the pilot's diabetes and treatment were not likely impairing at the time of the accident.
Tests and Research
A Garmin Aera 500 GPS device recovered from the wreckage was downloaded. Data indicated taxi began at 1509, departure from runway 01 at 1515, maneuvering, return and landing on runway 04 at 1537. Back-taxi and second takeoff began at 1538:08. At 1539:02, the airplane reached a maximum GPS altitude of 853 ft at 41 knots ground speed, then began a descending left turn, completed a 360° turn, and the last data point at 1539:49 was at 620 ft GPS altitude. During the final minute, ground speed peaked at 46 knots and decreased to 2 knots through the turn.