Accident Details
On April 20, 2009, at 1634 Pacific daylight time, a Cessna 152 (registration N48259) experienced a partial loss of engine power while maneuvering in the traffic pattern at McClellan-Palomar Airport (CRQ) in Carlsbad, California. The airplane was operated by Orion Aviation as a personal flight under Title 14 Code of Federal Regulations Part 91. The private pilot, the sole occupant, was not injured. The airplane sustained substantial damage to both wings and the fuselage. Visual meteorological conditions prevailed for the local area flight, and no flight plan had been filed. The flight had originated from CRQ about 1530.
Pilot Actions
According to the pilot’s written statement to the Federal Aviation Administration (FAA), he had been performing touch-and-go takeoffs and landings for approximately one hour. On the departure climb, the airplane reached an altitude of 800 feet. As the pilot initiated the crosswind turn, the engine began to run rough. Since the airplane was already at established pattern altitude, the pilot continued the flight and contacted Palomar tower, declaring an emergency. Suspecting carburetor icing due to humid conditions, the pilot activated the carburetor heat; however, there was no change in engine performance, indicating that was not the issue.
Tower personnel cleared the flight to land on either runway 6 or 24. At that point, the flight was on the downwind leg for runway 24, and the pilot reported that he was committed to landing on that runway. He observed a road on his flight path but did not consider it the best landing site due to traffic congestion; he also felt that a turn back to runway 6 was not feasible. The pilot stated that the engine rpm was 2,100 and the airplane's altitude was 700 feet. He believed he had sufficient power to reach the runway and was in control of the airplane.
While still on the downwind leg, the pilot trimmed the airplane for best glide, at which point the rpm dropped further to 1,700, accompanied by an increase in engine roughness. When he turned onto final approach, he believed there was a further drop in rpm. The pilot stated that he realized he would not make the runway. The airplane subsequently landed on its nose short of the threshold of runway 24.
Engine Inspection
The engine was inspected by Crownair Aviation of Carlsbad under the supervision of the FAA. Maintenance personnel reported carbon fouling of the number 2 cylinder bottom spark plug, which they reported could have caused a loss of engine rpm and a rough running engine. No other defects were noted during the engine inspection.