ERA15LA072

The student pilot reported that the preflight inspection and engine run-up revealed no anomalies and that he subsequently departed for a solo cross-country flight. About 30 minutes into the flight, the student pilot observed low cloud ceilings and decided to return to his departure airport. Two minutes after turning the airplane back toward the airport, the engine power dropped below 2,000 rpm. The student pilot applied carburetor heat, but the engine power did not increase, so he proceeded to a nearby airport to initiate an emergency landing. However, the engine continued to lose rpm during the approach, so he decided to land in a small field. During the landing, the airplane impacted a wire and then the ground, which resulted in substantial damage to the right wing and fuselage. Although the left magneto exhibited severe wear on the cam and burnt points, a single magneto failure would not have caused the loss of engine power. No other anomalies with the engine were found that would have precluded normal operation. Although atmospheric conditions at the time of the accident were favorable for the accumulation of carburetor icing at glide and cruise power, it could not be determined if carburetor ice was present when the loss of partial power occurred.

On December 5, 2014, about 1110 eastern standard time, a Cessna 150J airplane, N50709, was substantially damaged when it collided with terrain after a partial loss of power near Brookline Airport (NH16), Brookline, New Hampshire. The student pilot received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the cross-country flight, which departed from Lawrence Municipal Airport (LWM), Lawrence, Massachusetts, about 1000 and was destined for Dillant-Hopkins Airport (EEN), Keene, New Hampshire. The instructional flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. The student pilot reported that he had departed on his second solo cross country with about 20 gallons of 100LL fuel onboard. The airplane was in cruise flight at an altitude of about 2,500 feet mean sea level and on VFR flight following to remain under a cloud ceiling. About 30 minutes into the flight, the pilot noticed that the ceilings were lower than anticipated and decided to return to LWM. He turned the airplane around and two minutes later the engine rpm declined to below 2000 rpm. The pilot noted some abnormal resistance when he applied carburetor heat, but did not see a change in engine power once the carburetor heat was engaged. He then reported a "system malfunction" to Air Traffic Control and navigated the airplane towards NH16. The student pilot attempted to restart the engine three times while the airplane engine was still producing power. The airplane was gradually losing engine rpm while on approach to runway 01. With the airplane operating at a low airspeed, the pilot decided to avoid the possibility of stalling the airplane in a turn and decided to land in a small field. During the landing attempt the airplane "clipped the wire" and impacted the ground, which resulted in substantial damage to the right wing and firewall. During a follow-up conversation, the student pilot stated that the engine was preheated for about 20 minutes prior his departure on the accident flight. According to the student pilot, he performed a run-up on the day of the accident in accordance with the airplane's checklist and found no anomalies. He recalled that each magneto had dropped about "100-200 rpm" from the run-up tachometer reading of 2200 rpm. The student pilot also reported that he had difficulty applying carburetor heat, but noticed a drop in rpm once the carburetor heat was engaged. The student pilot also stated that the mixture was on the full rich setting during the entire flight. The airplane was a single-engine, all metal design that was manufactured in 1968 and equipped with a Continental Motors, Inc. O-200-A, 100 horsepower engine. A review of the airplane maintenance records revealed that the most recent 100-hour inspection was completed on August 10, 2014, at which time the engine had accrued 1,395 hours since major overhaul. According to the responding Federal Aviation Administration (FAA)inspector, the airplane came to rest a half mile southeast of the approach end of runway 01 in a small field adjacent to a road. The airplane was in a slight nose down attitude and oriented on a heading of about 075 degrees magnetic. The FAA inspector estimated about 10 gallons of fuel remaining in the wing tanks. From photographs, an outboard section of the right wing leading edge was impact damaged with traces of dirt, consistent with impacting the ground. The nose landing gear was found in the dirt about 25 feet from the main wreckage between two parallel landing gear marks. The propeller had one blade bent forward slightly, while the opposite blade was bent slightly aft. The airplane wreckage was moved to a hangar where a postaccident examination of the airplane was conducted by an FAA inspector and mechanic. Crankshaft and valvetrain continuity was established from the propeller to the rear accessory pad and all cylinders operated without anomaly. Thumb compression was confirmed on all cylinders by rotating the propeller by hand. All spark plugs were removed and inspected; the bottom plugs were oil soaked and top plugs contained high amounts of lead deposits. The carburetor was disassembled and examined; fuel was observed in the bowl and the accelerator pump operated without anomalies when tested. There were no anomalies with the carburetor float. There was excessive length within the carburetor heat cable that created an "S" turn at the engine truss, but the cable could be manipulated to operate the carburetor heat door. Both magnetos were rotated by hand and tested; the right magneto produced a spark on all towers and the left magneto produced a small spark. Disassembly of the left magneto revealed severe wear on the cam and burnt points. The carbon brush and rotor assembly exhibited wear as well. Review of the airplane maintenance records revealed that the Slick 4301 magnetos had not been overhauled or inspected since the engine's most recent overhaul, which took place on April 16, 1998. According to a representative of the magneto manufacturer, a single magneto failure would not have prevented the engine from producing power. The 1051 weather observation at Boire Field (ASH), Nashua, New Hampshire, located approximately 9 miles east of the accident site, included scattered clouds 2,800 feet, wind calm, temperature -1 degrees C, dew point -8 degrees C, and an altimeter setting of 30.65 inches of mercury. The carburetor icing probability chart from the FAA Special Airworthiness Information Bulletin (SAIB): CE-09-35 Carburetor Icing Prevention, June 30, 2009, showed a probability of light icing at cruise or descent power based on the temperature and dew point reported around the time of the accident.