Accident Overview
On March 20, 2012, about 1945 eastern daylight time, a Cessna 172K, registration N46492, experienced a partial loss of engine power during cruise flight near Belfast Municipal Airport (BST), Belfast, Maine. The certificated flight instructor (CFI) and student pilot were not injured during the off-airport landing to a road near BST. The airplane sustained substantial damage to the wings and fuselage.
Sequence of Events
The flight was operated by a local flight school under 14 Code of Federal Regulations Part 91 as an instructional cross-country flight. Night visual meteorological conditions prevailed, and no flight plan had been filed. The flight departed Hancock County-Bar Harbor Airport (BHB), Bar Harbor, Maine, about 1910, and was en route to Portland International Jetport (PWM), Portland, Maine.
According to written statements from the CFI and student pilot, after climbing to 6,500 feet above mean sea level, the engine began to "cough." The CFI placed the mixture control to "full rich" and applied carburetor heat. They decided to divert to BST, which was behind them but the closest airport. The CFI took control while the student pilot located the frequency and attempted to activate the pilot-controlled lighting. However, the runway lights could not be activated, so they attempted to land on the dark runway using the airport rotating beacon as a reference. The airplane was too far down the runway to land, and the CFI executed a go-around. During the climb out, the engine lost total power, and a forced off-airport landing was made. During the landing, the right wing struck a utility pole, causing substantial damage to the right wing and fuselage.
Aircraft and Pilot Information
The airplane was manufactured in 1968 and equipped with a 160-horsepower Lycoming O-320-E2D reciprocating engine. It was a four-place, all-metal, high-wing, single-engine, cantilever monoplane with fixed tricycle landing gear. The most recent 100-hour inspection was on December 6, 2011, at which time the airframe had 3,926.2 total hours time in service. The engine had 8,054.7 total hours, 256.7 hours since overhaul, and 18.6 hours since the most recent inspection.
Weather Conditions
At 1955, the recorded weather at Knox County Regional Airport (RKD), Rockland, Maine, located 21 miles south of the accident site, included wind from 280 degrees at 5 knots, visibility 10 miles, temperature 10°C, and dew point 6°C. According to the FAA Special Airworthiness Information Bulletin (SAIB) CE-09-35, based on the recorded temperature and dew point near the time of the accident, conditions were favorable for serious carburetor icing at cruise power setting.
Post-Accident Examination
An FAA inspector examined the airplane after the accident. The examination revealed damage to both wings, fuel leaking from the fuel tanks, slight curling at the propeller blade tips, and no damage to the engine. A test run of the engine was conducted; due to propeller damage, the engine was not run at full power but was operated above 1600 rpm with no abnormal sounds or discrepancies. When engine power was reduced to idle and carburetor heat applied, a rise of about 60 rpm was observed. The engine was then shut down using the mixture control with no anomalies. Photographs showed the airplane was equipped with two communication radios: "Comm 1" was tuned to Bangor Automated Flight Service Station, and "Comm 2" was tuned to BST common traffic advisory frequency (CTAF). The radio selector knob on the audio control panel was set to "Comm 1."