History of Flight
On August 25, 2012, at approximately 1045 central daylight time, an American AA-1 airplane, N5796L, struck terrain near Llano, Texas. The aircraft, owned by the student pilot, was operated by a private individual under 14 CFR Part 91 as an instructional flight. The flight departed from Llano Municipal Airport (KAQO) with visual meteorological conditions and no flight plan.
The airport manager observed the student adding fuel and pulling the airplane from the hangar. The manager saw the airplane depart and remain in the traffic pattern for practice takeoffs and landings. He informed the instructor via radio that a jet was scheduled to arrive around 1100, and the instructor acknowledged. No further communication occurred. At about 1400, the manager became concerned when the instructor's next student arrived. After contacting nearby airports, a local pilot searched and found the wreckage southeast of the runway.
A witness flying a helicopter near the airport at about 1045 reported seeing a flash of a wing and an airplane departing controlled flight toward the ground. He initially dismissed it as a radio-controlled airplane. Another witness observed an airplane on the downwind leg with a very high angle-of-attack and later saw the same behavior.
Personnel Information
The flight instructor held commercial pilot certificates for single- and multi-engine land and instrument airplane, along with flight instructor ratings for single-engine, multi-engine, and instrument airplane. He held a second-class FAA medical certificate issued August 31, 2011, with a requirement to wear corrective lenses. On his last medical application, he reported 8,577 total flight hours, with 783 in the previous six months.
The student pilot did not hold a student pilot or medical certificate. He had applied for a medical certificate on August 17, 2012, but it was not issued pending additional information. His logbook showed 14.7 total flight hours, with 12.5 in the accident airplane. The last entry was August 24, 2012. The logbook recorded two flights in February and one in March with a different instructor in a different aircraft type. Starting June 29, 2012, the student and accident instructor flew weekly in the accident airplane. The last five entries were annotated as patterns and touch-and-goes; no stall or spin avoidance training was noted.
Aircraft Information
The accident airplane was a 1969 American AA-1, an all-metal, side-by-side two-seat low-wing airplane with fixed landing gear. It was powered by a 108 hp Lycoming O-235-C2C engine driving a fixed-pitch two-bladed metal propeller. The student pilot purchased the airplane in April 2012. The most recent annual inspection was completed June 26, 2012, with an airframe total time of 1,683.01 hours. Maintenance records noted an ELT inspection with no defects and a new battery due date of May 2014.
Meteorological Information
At 1055, the automated weather observation at KAQO recorded wind from 190 degrees at 13 knots, gusting to 16 knots, visibility 10 miles, clear skies, temperature 86°F, dew point 44°F, and barometric pressure 29.95 inHg. A review of the carburetor icing probability chart from FAA Special Airworthiness Information Bulletin CE-09-35 indicated that conditions were favorable for serious carburetor icing at glide power.
Airport Information
Llano Municipal Airport (KAQO) is a public-use airport about two miles northeast of Llano, Texas. It is a non-towered airport using the Common Traffic Advisory Frequency. It has a 4,202-foot by 75-foot asphalt runway (17-35) and a 3,209-foot by 150-foot turf runway (13-31).
Communications
The pilot was not in contact with air traffic control, and no distress calls were reported.
Wreckage and Impact Information
The wreckage was located in a lightly wooded area with cactus, about one mile southeast of the airport. Two ground impact scars were found in front of the wreckage. The engine and front fuselage were extensively crushed. Both wings remained attached but had broken wing spars at the root and extensive buckling and dents. The damage was consistent with a steep nose-down collision with terrain. The left and right wing fuel tanks (also the main wing spar) were breached and empty; no vegetation blight or fuel odor was detected.
The propeller remained bolted to the crankshaft. One blade had a slight bend, intact tip paint, and no leading edge gouges. The other blade was bent back at mid-span at an estimated 45-degree angle, with scratches and polishing near the bend. The engine starter had an impact mark but no rotational scoring. The empennage had minor damage; rudder, elevator, and trim tab remained attached. The ELT activation switch was found in the off position.
Medical and Pathological Information
Autopsies conducted by the Travis County Medical Examiner's Office determined the causes of death for both occupants as blunt force injuries. FAA toxicology testing on the flight instructor was negative for carbon monoxide, cyanide, and ethanol. Diphenhydramine was detected in liver and cavity blood at 0.051 µg/ml. Testing on the student pilot was also negative for carbon monoxide, cyanide, and ethanol. Alpha-hydroxyalprazolam was detected in urine but not in blood; alprazolam was not identified.
Tests and Research
Control continuity was established from the control surfaces to the cabin section. The stall warning switch was removed and tested; initially no continuity, but after reassembly with cleaned contacts, continuity was observed. A mechanic's work order dated August 3, 2013, noted "adjusted stall warning." A family member reported that the student pilot mentioned a couple days before the accident that the stall warning still was not working right and that the flight instructor would disable it for each flight.
The engine exhibited heavy impact damage. Continuity through the crankshaft, pistons, camshaft, and valve train was established. A thumb compression test was performed on each cylinder. The two magnetos separated from the engine and could not be tested. The engine drive fuel pump was broken but free to move. Rocker covers were removed and valves moved when the engine was rotated. The carburetor was damaged, with the fuel inlet screen free of debris. The float bowl contained residual fuel; floats were free and undamaged. A water detection test on the fuel was negative. Spark plugs displayed light gray deposits consistent with normal combustion.