SAN LUIS OBISPO, CA, USA
N3477Q
Piper PA-28-181
The flight instructor and student obtained an instrument departure clearance to climb to VFR on top for a cross-country flight. After reaching VFR on top, the engine rpm decreased to about 1,800 and then to 1,500. Following unsuccessful attempts to restore power, the instructor descended through the stratus cloud deck and became VFR about 700-800 feet msl. The power level was insufficient to reach the airport and he landed in an open field. Examination of the carburetor revealed a fibrous material inside the throat similar to the lining found inside the intake duct. The duct had evidence of a prior carburetor fire, which had caused a deterioration of the duct. The last maintenance inspection on this rental aircraft was 50 hours prior to the accident.
On July 6, 1999, about 0815 hours Pacific daylight time, a Piper PA-28-181, N3477Q, operated by Cal Coast Flyers, Inc., was substantially damaged during a forced landing near San Luis Obispo, California. The forced landing was precipitated by a loss of engine power during the climb to cruise phase. Neither the certified flight instructor nor the student pilot was injured. Instrument meteorological conditions prevailed at both the departure airport and the accident site. The instructor had received an instrument clearance for an IFR climb to VFR conditions on top. The cross-country instructional flight, conducted under the provisions of 14 CFR Part 91, departed at 0800 and was en route to Santa Monica, California. After reaching VFR on top, about 1,800 feet msl, the instructor reported that he applied carburetor heat to the engine. At that point, the engine revolutions decreased to 1,800 and then to 1,500 rpm. The instructor was unsuccessful in restoring full engine power, and, the power output was insufficient to maintain altitude. He then descended through the stratus cloud deck, broke out at 700-800 feet msl, and landed in an open field. During the landing roll, the aircraft collided with ground obstructions. Examination of the engine by an Federal Aviation Administration inspector from the San Jose Flight Standards District Office revealed a fibrous material contaminating the inside of the carburetor throat. Further examination of the induction system revealed a burned and torn carburetor inlet hose. The last maintenance inspection of the engine on this rental aircraft occurred 50 hours prior to the accident.
A loss of engine power due to contamination of the induction system and the carburetor throat. Factors in the accident were a prior undetected carburetor fire, which caused a deterioration in the air duct material.
Source: NTSB Aviation Accident Database
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