IAD96LA131

The flight instructor (CFI) and student discussed a preparatory flight for the student's upcoming check flight. The accident site was where the flight instructor flew his students to practice maneuvering with the airplane. A witness on the ground stated that he was in a field when he heard an airplane coming from behind. He turned, then observed the airplane fly overhead. Once past him, the witness noted that the airplane engine sound seemed to go to a steady state. The witness stated that the airplane went out of his view, and he did not see the airplane hit the ground. The airplane cleared a set of residential power lines and impacted in a grassy, rough pasture. Ground scars showed that the airplane traveled about 60 feet from the initial impact point, coming to rest in an inverted position facing the direction of the ground scars. The wreckage showed that the airplane impacted the ground in a nose low, right wing down attitude. The temperature and dew point were reported to be 70 and 58 deg, respectively. According to icing probability charts, conditions were conducive to carburetor ice; however, carburetor icing was not verified.

HISTORY OF FLIGHT On August 10, 1996, at approximately 1101 eastern daylight time, a Cessna 150F, N6984F, operated as a dual instructional flight, impacted the ground near Greenfield Township, Pennsylvania. The certificated flight instructor and the student pilot were seriously injured and the airplane was destroyed. No flight plan had been filed and visual meteorological conditions existed at the time of the accident. The flight was conduct under 14 CFR Part 91 and the owner of the airplane estimated that the flight originated at approximately 1030 eastern daylight time from Moorhead Airpark, in North East, Pennsylvania.

The flight instructor and the student had discussed that this would be a preparatory flight for the student's upcoming check flight. A witness in a field near the accident site stated that he heard the airplane coming from behind. He stated that it sounded like the engine was cutting in and out, and he thought it was a friend trying to get his attention. He stated that he turned to wave when the airplane passed overhead. The witness stated that once the airplane went past him, the airplane engine sound seemed to go to a steady state, but was unable to stated a power setting since the airplane was moving away from him. The witness stated that the airplane went out of his view. He stated that he did not see the airplane impact the ground.

PERSONNEL INFORMATION According to the Pilot/Operator aircraft accident report filled out by the registered aircraft owner, the certificated flight instructor had a total of 275 flight hours, 10 hours as a flight instructor. The certificated flight instructor had 1 flight hour in the last 24 hours, 10 flight hours in the last 30 days and 19 total flight hours in the last 90 days.

The student pilot onboard the airplane had a total of 35 flight hours. The registered aircraft owner stated that he had had 0 flight hours in the last 24 hours, 5 hours in the last 30 days, and 10 hours in the last 90 days.

AIRCRAFT INFORMATION According to the FAA Inspector no airframe or engine anomalies were found in the maintenance logbooks.

METEOROLOGICAL INFORMATION The weather conditions at 1054 local time at Erie International Airport, Erie, Pennsylvania which is approximately 18 miles to the west was: Winds-330 degrees at 8 knots; Visibility- 10 miles; Temperature- 70 degrees Fahrenheit; Dewpoint- 58 degrees Fahrenheit; Altimeter-30.16 inches of Hg. These conditions are favorable to carburetor icing.

WRECKAGE AND IMPACT INFORMATION The Federal Aviation Administration Inspector arrived on scene 4 to 5 hours after the accident, stated the airplane impacted the ground with a nose low and right wing down attitude. The Inspector stated that the airplane passed over power lines suspended about 40 feet above the ground and from the initial point of impact traveled approximately 60 feet and came to rest in an inverted position facing the direction of the ground scars it had created. The right main landing gear and nose landing gear assemblies were found separated from the airframe. The FAA Inspector stated that the rescue squad personnel pointed out that the nose landing gear assembly was found in the cockpit area and had to be removed prior to the extraction of the crew.

Due to the seriousness of the injuries sustained by both the certificated flight instructor and the student pilot and their lack of recall for any events prior to the accident, an inspection of the wreckage was conducted by the NTSB Investigator In Charge assisted by representatives from the engine and airplane manufacturers at Moorhead Airpark in Northeast, Pennsylvania, on August 21, 1996. The right main landing gear steel tube was found with little or no curvature and the emphennage section of the airplane had bent/flexed downward. As the engine was being removed from the nose section of the airplane, it was noticed that the throttle rod and cable assembly was found broken at the rod portion of the assembly. The unit was removed in two pieces and taken to the Office of Research and Engineering, Materials Laboratory Division, National Transportation Safety Board, Washington, D.C. for further analysis.

ADDITIONAL INFORMATION The two segments of the throttle cable and connecting assembly were inspected and the fracture plane was cup shaped typical of a cup-cone fracture consistent with a ductile overstress separation.