LAX06LA044

The airplane landed hard during a forced landing following a loss of engine power in cruise flight. After a normal departure the airplane climbed to about 4,800 feet mean sea level (msl). The pilot noticed an audible difference in the engine operation, as if it were making intermittent pauses. As he was flying back to the airpark the engine continued to operate abnormally and began to make severe "popping" sounds. Despite the pilot's efforts, the engine failed to respond to his troubleshooting attempts and subsequently lost power. The airplane touched down about 1/3 down the runway, contacting the surface hard. A post-accident inspection preformed by a Federal Aviation Administration certificated mechanic who also holds an Inspection Authorization (IA) revealed that the mixture cable had disconnected at the carburetor. Specifically, the mixture linkage was separated where the cable adjoins the mixture control arm. The pilot and mechanic opined that the separation of the linkage would decrease the fuel supply and alter the fuel/air ratio, resulting in a subsequent loss of power. The airplane had last undergone an annual inspection 44 flight hours prior to the accident; the cable was last inspected at that time. The pilot stated that due to the location of the mixture cable, the mechanic would have to remove the cable from the throttle arm to inspect it in its entirety. The airplane's service manual states that during every 100-hour inspection the mechanic should inspect the mixture cable for, "travel and operating condition."

On November 20, 2005, at 1710 mountain standard time, a Piper PA-24-250, N7466P, experienced a loss of engine power and landed hard at the La Cholla Airpark, Tucson, Arizona. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The commercial pilot and right-seated rear passenger were not injured; the front-seat passenger sustained minor injuries. The airplane sustained substantial damage. The personal cross-country flight was originating from La Cholla Airpark with a planned destination of Klamath Falls, Oregon. Visual meteorological conditions prevailed, and a flight plan had not been filed.

In a written statement, the pilot reported that he completed a normal takeoff and departed the traffic pattern. As the airplane climbed to about 4,800 feet mean sea level (msl), the pilot noticed an audible difference in the engine operation, as if it were making intermittent pauses. He opted to return to the airpark. He maneuvered the airplane to the downwind leg of the traffic pattern for runway 19. The engine continued to operate abnormally and began to make severe "popping" sounds. Despite the pilot's efforts, the engine failed to respond to his troubleshooting attempts and subsequently quit. The pilot turned the airplane early onto the base leg and continued onto final. The airplane touched down hard, contacting the surface about 1/3 of the way down the runway. The landing gear collapsed and the airplane came to rest about halfway down the runway.

The pilot further stated that the day following the accident, he had an Inspection Authorization (IA) mechanic perform an inspection of the airplane. The inspection revealed that the mixture cable had disconnected at the carburetor. Specifically, the mixture linkage was separated where the cable adjoins the mixture control arm. The pilot and mechanic opined that such a separation of the linkage would decrease the fuel supply and alter the fuel/air ratio, resulting in a subsequent loss of power.

The pilot added that the airplane had last undergone an annual inspection on May 15, 2005, equating to 44 flight hours prior to the accident. The cable was last inspected at that time. The pilot stated that due to the location of the mixture cable, the mechanic would have to remove the cable from the throttle arm to inspect it in its entirety.

According to a representative from the airplane manufacturer, both the pilot and mechanic would see evidence of cable wear prior to it separating. He stated that during routine maintenance a mechanic would be able to see rubbing, bending, corrosion, or severe wear on the cable. He additionally said that a pilot would be able to feel the cable binding or the whole cable assembly moving prior to breaking.

According to 14 CFR Part 43 Appendix D - Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100-Hour Inspections, each person performing an annual or 100-hour inspection shall inspect (where applicable) the engine and nacelle group. This includes "engine controls- for defects, improper travel, and improper safetying."

The airplane's service manual states that during every 100-hour inspection the mechanic should inspect the mixture cable for, "travel and operating condition."