NTSB Factual Report

HISTORY OF FLIGHT

On April 11, 2015, about 1307 eastern daylight time, an Aeronca 7AC, N82658, was substantially damaged during landing rollout when the right main landing gear collapsed after a loss of power and forced landing near Spring City, Tennessee. The private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under Title 14 Code of Federal Regulations Part 91 which departed Western Carolina Regional Airport (RHP) Andrews, North Carolina destined for Warren County Memorial Airport (RNC), McMinnville, Tennessee.

According to the pilot, the purpose of the flight was to return the airplane to his home airport, as the airplane had been at RHP since August of 2014, having the fabric covering replaced, and receiving an annual inspection.

The pilot and his wife had driven over to RHP on the day before the accident. On the morning of the accident at approximately 0824 the pilot called the RHP automatic weather observing system to check on the weather conditions that existed at the airport. The weather forecast called for a slight wind from the north-northeast with clear visibility and barometric pressure reading of 30.20. He advised that he had chosen this day to pick up the airplane due to a clear national weather service forecast with low wind speeds for both RHP and RNC.

He arrived at RHP at approximately 1000 to preflight the airplane. After meeting with the maintenance provider's personnel and picking up the airplane's logbooks, they pushed the airplane out of the hangar and conducted a preflight walk around check. The pilot then taxied the airplane to the fixed base operator's facility and topped off the fuel. After fueling was completed, the pilot started the engine and taxied out to Runway 8 and performed a pretakeoff procedure check. The pilot advised that the wind was basically calm (3 to 5 knots from the northeast). Then after the pre-takeoff check was performed, he took off. He flew a right-hand traffic pattern three times, making three takeoff and landings (two, three-point landings and one, wheel landing) to ensure all was well for the upcoming flight to RNC. The pilot stated that "the champ performed flawlessly."

He taxied back to the maintenance provider's facility, to indicate all was well. After a brief discussion about how great the airplane was flying, the pilot then started the engine, taxied out, did another pre-takeoff check and then departed at approximately 1200 for RNC.

The pilot further stated that since RHP lies in a valley, you must fly the valley at Vx (50mph) best angle of climb to gain altitude to clear the mountains. He climbed to 6,500 feet above mean sea level (msl) and then flew over them. Once he was out of the mountains, he decreased engine rpm and leveled off at an altitude of approximately 2,500 feet msl and flew at a cruise speed of 74 knots indicated airspeed at 2,150 rpm for approximately 30 minutes.

When he was approximately 50 nautical miles from RNC, an increase in altitude was needed to climb over the Cumberland Plateau at a safe altitude. He applied climb power and the engine started sputtering and losing rpm. The oil pressure gauge and temperature instruments indicated that oil temperature and pressure were fine, so he applied carburetor heat. The engine rpm then increased, and he gained altitude momentarily, but the engine started sputtering again, and this time, the carburetor heat had no effect. He then checked the fuel cutoff value to make sure it had not moved to the off position, then quickly checked the magnetos by rotating the magneto switch from "both to left and then back to right". No change in the engine sputtering was noticed when he moved the switch from the left magneto to the right magneto, so he moved it back to both. He also checked his fuel quantity by visually looking at the fuel gauge, and cork fuel float gauge which was physically located on the fuel tank. Both indicated that almost a half a tank of fuel was left remaining.

He was losing altitude, so he began to look for a place where he could land safely. No radio transmissions were made by the pilot as he was totally devoted to flying the airplane. He was over a populated area and he could see that people were outside. The engine was still sputtering with low rpm and he was losing altitude. He felt he had no choice but to attempt an emergency landing. He spotted a farmer's field with a barn on the south end of the field where two farmers were working with their cattle. He turned north into the wind and began a glide to put it down in the field, gliding right over a barn. His speed was a little above the Vg (60 mph) recommended landing approach glide, but he had to put it down quickly since the field was short and he had to clear the barn. When he landed the right main landing gear collapsed and forced the right wheel up into the right forward wing strut. The airplane then did a flat, slow, 180-degree ground loop to the right. The pilot then unbuckled his shoulder straps and seat belt and exited the airplane.

PERSONNEL INFORMATION

According to Federal Aviation Administration (FAA) and pilot records, the pilot held a private pilot certificate with a rating for airplane single-engine land. His most recent FAA third-class medical certificate was issued on March 3, 2015. He reported that he had accrued 1,188 total hours of flight experience, 480 of which were in the accident airplane make and model.

AIRCRAFT INFORMATION

The accident airplane was a two place, tandem configuration, high wing monoplane. It was equipped with fixed conventional landing gear comprised of steel tube main gear and a steerable tailwheel.

The fuselage and tail surfaces were constructed of welded metal tubing. The outer shape of the fuselage was created by a combination of wooden formers and longerons covered with fabric.

The strut-braced semi-cantilever wings like the fuselage and tail surfaces, were also fabric-covered, and used aluminum ribs.

It was powered by a four-cylinder, air cooled, horizontally opposed, 65 horsepower, Continental A-65-8 equipped with a bottom-mounted Marvel Schebler updraft carburetor fuel delivery system with a carburetor heater, which controlled the flow of heated air from the engines crankcase baffle system to the carburetor venturi. A butterfly valve connected to the carburetor heater control cable would direct the airflow to the carburetor, when desired by the pilot, or through an outlet at the bottom of the air scoop assembly when not in use.

According to FAA and airplane maintenance records, the airplane was manufactured in 1946. The airplane's most recent annual inspection was completed on April 4, 2015. At the time of the inspection, the airplane had accrued approximately 2134.5 total hours of operation, and the engine had accrued approximately 255.3 total hours of operation since major overhaul.

METEOROLOGICAL INFORMATION

The reported weather at Crossville Memorial Airport – Whitson Field (CSV), Crossville, Tennessee, located 18 nautical miles northwest of the accident site, at 1253, included: winds 050° at 8 knots, 10 miles visibility, clear, temperature 18° degrees C, dew point -02° C, and an altimeter setting of 30.22 inches of mercury.

Review of the reported weather at CSV and a carburetor icing probability chart indicated that the dew point depression (which is the difference between the temperature and dewpoint) around the time of the accident was about 2.2° C, the humidity was about 85%, and the air temperature was about 18° C, indicating the airplane would have been subject to moderate carburetor icing at cruise power, and serious icing at descent power.

WRECKAGE AND IMPACT INFORMATION

Examination of the airplane by an FAA certificated airframe and powerplant mechanic revealed, that the right axle strut, and oleo case frame assembly had been damaged during the forced landing, collapsing the right main landing gear. The right main landing gear wheel had then struck the right forward wing strut (which transmitted the flight and landing loads from the semi-cantilever wing to the fuselage), and bent it about 22°, resulting in substantial damage.

Examination of the engine revealed no evidence of debris in the fuel screens or carburetor float bowl. The carburetor float bowl contained fuel, and the fuel appeared to be free of water contamination. the fuel passages were clear, and the accelerator pump was functional. The float assembly functioned smoothly. The air inlet to the carburetor was clear of obstructions and the air filter was in its mounting location and was clean. The magnetos were still securely attached to their mounting locations.

A test run of the engine was conducted, and the engine started on the first pull of the propeller. After starting, the engine was run at full and partial throttle settings, without any anomalies being noted.

NTSB Probable Cause

The pilot's failure to properly apply carburetor heat in conditions conducive to carburetor icing, which resulted the accumulation of carburetor ice and the subsequent total loss of engine power.