Aviation Accident Summaries

Aviation Accident Summary CHI97LA201

HERMANN, MO, USA

Aircraft #1

N1142J

WEBER RV-4

Analysis

On the third final approach to land the airplane on a hilly turf runway, the pilot discovered that the throttle cable had jammed at a reduced power setting. The jammed throttle prevented him from either reducing power to land or from applying full power to go around. The pilot successfully flew past power lines and poles before initiating a turn to avoid timber on a ridge, but was unable to clear rising terrain due to inadequate power for the climb. He said that he stalled the wings prior to impact with terrain. The pilot said things happened so fast on final that he did not have time to think about shutting off the engine. The airplane impacted in a steep hay meadow approximately 50 feet above the highest point on the runway. Investigators found the throttle cable jammed due to broken strands of cable inside the sheath. The throttle cable, which had been salvaged from another airplane, showed extensive chafing at several places on the sheath from the previous installation.

Factual Information

On July 4, 1997, at 1407 central daylight time, (cdt), a Weber RV-4, N1142J, owned and operated by a private pilot, sustained substantial damage while attempting a go-around. The airplane impacted terrain on its third go-around while trying to land on a private airstrip near Hermann, Missouri. The pilot reported serious injuries. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed. The flight departed Celina, Texas, at 1100 cdt. According to the pilot's written statement, he was on short final to land when he realized that his power lever was stuck at a low power range. The pilot realized this condition as he tried to pull the power back to idle. The pilot then tried to added power to do a go around but the engine did not respond. The pilot turned the airplane to the right to avoid hitting rising terrain. He said that the airplane was not climbing enough to clear the rising terrain and said the airplane impacted terrain after he "stalled" the wings. He said that he installed a used throttle cable out of a 1960 Cessna 172. He went on to say "should have installed new cable when A/C was built." Hills and trees obstruct the landing environment on final approach from the south. A north-south turf runway approximately 1600 feet long had been mowed out of a hay meadow across the top of a 30-foot high hill. The landing run-out area to the north slopes downhill across a gravel drive towards a fence. Beyond the fence to the north lies another hill at least 100 feet tall which is crested with 50 feet of standing timber. A power line suspended between telephone poles is located immediately to the east of the runway at midfield. The pilot, who had landed this airplane on this site several times before, approached from the south in moderate winds and gustiness. Witnesses reported that the airplane failed to touch down, overflew the landing area at a low altitude, flew past the telephone poles, and turned right towards the east. The airplane failed to clear the rising terrain and impacted with flaps partially extended in a hay meadow on the side of a hill. The pilot's father who witnessed the accident, said his son [pilot] reported at the scene, and later told him during his recovery, that his throttle had stuck at a low setting, preventing him from reducing power enough to land and likewise preventing him from applying sufficient power to execute a successful go-around. The witness went on to say that his son [pilot] stated that everything happened so fast on final that he did not have time to think about shutting off the engine with the fuel or ignition to make a power off landing. A federal Aviation Administration Principal Operation Inspector (POI), represented the NTSB on-scene. The POI confirmed that the engine was producing power at the time of contact with terrain. The impact fractured the carburetor housing at the butterfly valve, however, he was able to establish freedom of movement of the throttle body and continuity and proper attachment to the throttle arm. The POI noted that the throttle cable was old, and at several places revealed chafing through an external protective cover. This wear, which does not match contact places in the current installation, appears to have occurred during a previous installation. The POI found the throttle cable stuck, and through close examination concluded that broken strands of the steel cable had become jammed inside the external sheath. The FAA POI concluded that a continuity check of all other flight controls revealed no anomalies. Fuel was observed in the wing tanks, and no evidence of fuel leakage was noted.

Probable Cause and Findings

the pilot's inadequate in-flight planning/decision and encounter with a stall. Related factors were the chafed throttle cable, which became jammed; and failure of the pilot to perform an engine shut down in order to land on the runway.

 

Source: NTSB Aviation Accident Database

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