Accident Overview
On July 16, 2016, at about 1020 mountain daylight time, an Aeronca 7BCM airplane, registration N2576E, impacted terrain while departing from Vance Brand Airport (LMO) in Longmont, Colorado. The pilot, the sole occupant, sustained minor injuries, and the airplane was substantially damaged. The airplane was registered to and operated by 2576E LLC under 14 CFR Part 91 as a personal flight. Day visual meteorological conditions prevailed, and no flight plan was filed.
Preflight and Takeoff
The pilot had serviced the airplane with 10 gallons of aviation fuel the day before, bringing total fuel onboard to 13 gallons. On the day of the accident, the elapsed time from engine start to takeoff roll was less than 5 minutes. During the engine runup at 1,700 rpm, the pilot checked the carburetor heat and magnetos, which he reported as normal. He recalled the wind as calm.
During the takeoff roll on Runway 29, the pilot observed the engine producing only about 2,000 rpm, compared to the typical 2,200 rpm. He continued the takeoff and noted a significantly longer takeoff roll. After liftoff, the airplane was unable to climb normally. After reaching about 200 ft above ground level (agl), the pilot executed a forced landing due to concerns about terrain. During the forced landing, the airplane hit power lines, skipped across a road, and nosed over, damaging both wings.
Witness Observations
A pilot witness near the departure end of the runway observed the airplane lift off much later than expected, approximately 3,000 ft down the 4,799-ft-long runway. After liftoff, the witness noticed the airplane climb slowly to about 200 ft, then bank left and descend out of sight. The witness also observed a windsock indicating a tailwind of 3 or 4 knots.
Weather Conditions
At 1014, the automated weather observation station at LMO reported wind calm, visibility 7 miles, clear skies, temperature 24°C, dew point 14°C, and an altimeter setting of 29.98 inHg. At 1034, the wind was from 100° at 4 knots. Density altitude was calculated to be 7,388 ft. The FAA icing probability chart indicated potential for serious carburetor icing at glide power at the time of the accident.
Post-Accident Examination
FAA inspectors examined the airplane. The fuel from the main tank had leaked out while the airplane was inverted after the accident. The gascolator contained about 2 ounces of fuel, which was clear and bright, with no water or debris. No anomalies were noted with the ignition or carburetor systems. Compression testing of the cylinders yielded normal results. Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.