Accident Overview
On August 29, 2010, at 1428 eastern daylight time, a Cessna 120, registration N2493N, was destroyed when it impacted terrain after a loss of engine power following takeoff from Knox County Regional Airport (RKD) in Rockland, Maine. The certificated private pilot, who was the sole occupant, was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91.
Pilot's Account
According to the pilot, during the takeoff roll on runway 31, he noticed the engine “wasn’t producing as much power as it should have been.” Believing he could not safely turn back to the airport, he decided to perform a forced landing straight ahead. During the landing, the airplane struck trees before coming to rest on the ground.
The pilot reported that he had fueled the airplane approximately 10 days before the accident, after his last flight, by “topping the fuel tanks” with 100LL aviation fuel. He also stated that the carburetor heat was “off” during the takeoff.
Witness Observation
A witness flying in the traffic pattern at RKD observed the accident airplane depart from runway 31 and “appeared to be having difficulty gaining altitude.” As the airplane passed the intersection of runways 21 and 31, it drifted to the northeast side of the runway while still appearing to struggle with altitude. Continuing to the northwest, it made a couple of shallow turns, eventually turning west at low level. The witness lost sight of the airplane as it descended behind trees west of the approach lights for runway 13.
Post-Accident Examination
An FAA inspector examined the wreckage. The airplane was mostly consumed by a post-crash fire. Flight control continuity from the cockpit to the control surfaces was confirmed. The engine was rotated, revealing continuity of the crankshaft, camshaft, and valve train. Both magnetos showed severe fire damage; however, the impulse coupling of the left magneto operated when the engine was rotated. The spark plugs appeared “extremely worn.” Examination of the propeller showed one blade bent aft approximately 30 degrees and the other blade straight; neither blade had rotational scoring.
The carburetor and magnetos were removed and disassembled; no pre-impact mechanical anomalies were noted. The fuel selector was found in the right tank position.
Pilot Information
The pilot held a private pilot certificate with a single-engine land rating. His most recent third-class medical certificate was issued on April 14, 2008, at which time he reported 181 hours of total flight experience.
Weather Conditions
Weather recorded at RKD at 1355 included wind from 260 degrees at 9 knots, gusting to 14 knots, 10 miles visibility, clear skies, temperature 30°C, dew point 18°C, and altimeter setting 30.02 inches of mercury.
Carburetor Icing Potential
A review of the FAA Carburetor Icing Probability Chart, based on the atmospheric conditions during takeoff, indicated that the airplane was operating within the "serious icing – glide power" range.