LEXINGTON, TN, USA
N7102F
Cessna 150F
The pilot initially attempted to takeoff with a slight quartering tailwind, but he aborted the takeoff, then initiated a takeoff into the wind. Takeoff distance calculations showed that 1,315 feet would be required to clear a 50-foot obstacle. The airplane was observed to rotate about 4,300 feet down the 5,000 foot runway, climb to about 150 to 200 feet agl, roll left, then pitch nose down. The airplane impacted the ground nose and left wing low. Examination of the flight control systems revealed no evidence of a preimpact failure or malfunction. Examination of the engine revealed that the No. 4 cylinder exhaust valve was open. Dimensional measurements of the exhaust valve stem and the valve guide revealed that they had less then the minimum clearance as required by the overhaul manual. Review of the engine logbooks revealed that the engine was overhauled by an A & P mechanic in 1988. The overhaul manual indicated that after replacement of the exhaust valve guides, they were to be reamed to size. The engine had accumulated 443.96 hours since overhaul at the time of the accident. A pilot, who had flown the accident airplane on a previous flight, noted excessive rpm drop during the carburetor heat check. The airplane owner had been notified of the excessive rpm drop, but review of the maintenance records did not reflect that engine maintenance was performed.
HISTORY OF FLIGHT On October 19, 1996, about 0945 central daylight time, a Cessna 150F, N7102F, registered to Floriplex, Inc., crashed shortly after takeoff from the Franklin Wilkins Airport, Lexington, Tennessee. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the private-rated pilot and one passenger were seriously injured. The flight originated from the airport about 3 minutes earlier. The pilot stated that he has no recollection of the accident and that he rented the airplane from the owner. He also stated that he did not perform weight and balance calculations before the flight. According to a witness, he advised the pilot not to utilize the sod runway because "the plane was a sick airplane and the runway was only 2,200 feet long." The pilot advised him he would use the paved runway and attempted to takeoff initially from runway 15. The witness observed the airplane rotate about 2,000 feet down the 5,000-foot runway then settle onto the runway and rotate again but again settled onto the runway. The pilot then aborted that takeoff and the witness further stated that he thought the pilot would abort the flight and return to the hangar, but the pilot then attempted to takeoff from runway 33. The airplane became airborne about 4,300 feet down the 5,000 foot runway and while in a nose-high attitude, climbed to about 150-200 feet above ground level then rolled to the left and pitched nose down. He lost sight of the airplane due to obstructions then heard the impact. PERSONNEL INFORMATION Information pertaining to the pilot is contained on page 2 of the NTSB Factual Report-Aviation. Additionally, according to his latest medical certificate, he weighed 265 pounds. The passenger stated that he weighed between 145 and 150 pounds at the time of the accident. AIRCRAFT INFORMATION Information pertaining to the airplane is contained on page 2 of the Factual Report-Aviation. Review of the engine logbook revealed that it was last overhauled on May 21, 1988, by an FAA certificated Airframe and Powerplant (A & P) mechanic who was also the previous registered owner of the airplane. Numerous attempts to contact the mechanic were unsuccessful. Review of the engine logbook pertaining to the overhaul revealed that in part, new exhaust valves and guides were installed for all four cylinders. The entry indicates that the mechanic followed the engine manufacturer overhaul manual. The engine had been operated for 443.96 hours since overhaul and 10.5 hours since the airplane was purchased by the current owner. According to a pilot who flew with the accident pilot on August 8, 1996, in the accident airplane on two separate flights lasting a total of about 3 hours, there was no evidence of an engine malfunction on either flight. A certified flight instructor who had flown the accident airplane on three separate flights, twice on August 11, and once on August 25, 1996, stated he thought the acceleration was "sluggish" during each takeoff roll but he did not calculate the takeoff distance for the flights. He also stated that before the first flight on August 11th, he had never flown a Cessna 150 airplane. The purpose of the first flight on August 11 was for aircraft familiarization and also to document discrepancies related to the airspeed indicator, suction gauge, and attitude indicator noted by the accident pilot who had flown the airplane 3 days earlier. The CFI noted that there was a noticeable rpm drop (400-500 rpm) when carburetor heat was applied at 1,700 rpm during the before takeoff checklist. He also noted that during the takeoff roll, the rpm gauge indicated 2,400 to 2,450. The next flight that day was with a student and again the rpm drop was excessive when the carburetor heat was checked during the before takeoff checklist. During the takeoff roll the rpm indicated the same and he noted excessive rpm drop when carburetor heat was applied in the downwind leg. The third flight on the 25th was with a rated pilot and again during the carburetor heat check on the ground excessive rpm drop was observed. Before the takeoff with full power and the brakes applied, he noted that the static rpm was 2,400 to 2,450 rpm. The flight departed from the grass runway which has a slight upslope and he stated that the airplane barely cleared trees at the departure end of the runway. The flight returned and landed uneventfully; but then during a preflight of the airplane for another flight that day, water was noted in one of the fuel tanks. He canceled that flight and advised the owner of the airplane about the discrepancies relating to the airspeed indicator, suction gauge, attitude indicator, water in the fuel system, and the excessive rpm drop when carburetor heat was applied. He did not advise the owner about the incident in which the airplane barely cleared trees at the departure end of the grass runway. Review of the engine logbook for the period when the CFI flew the airplane revealed only one entry dated August 11, 1996, in which the engine oil was changed. Review of the airplane operating limitations indicates that the gross weight of the airplane is 1,600 pounds. Review of the airplane type certificate data sheet revealed that the minimum and maximum static rpm at full power with the installed propeller is 2,375 to 2,475 respectively. Additionally, the maximum rpm for the engine is 2,750 rpm. According to a Cessna Safety Supplement for the airplane, the maximum carburetor heat drop at full throttle is approximately 150 rpm. METEOROLOGICAL INFORMATION Visual meteorological conditions prevailed at the time of the accident. At 0940 CDT at the departure airport, a weather observation indicated in part that the wind was from 040 degrees at 3 knots. Additional meteorological information may be obtained on page 4 of the Factual Report-Aviation. WRECKAGE AND IMPACT INFORMATION The airplane was moved from the accident site before examination of it by the FAA and representatives of the airframe and engine manufacturer. The accident site was located adjacent to a high school building. Ground scars on grass adjacent to a small tree were noted and the flight path of the airplane was estimated to be on a magnetic heading of about 200 degrees. The airplane came to rest against another tree about 49 feet from the initial impact point. Examination of the airplane revealed that all components necessary to sustain flight were attached to the airframe. According to the Cessna representative, chordwise crushing was noted on nearly the complete span of the leading edge of the left wing and on only the outer half of the right wing. Review of photographs taken by the representative revealed that the left and right wing tips were displaced up. Also, the aft inboard section of the left wing was displaced toward the fuselage. The fuselage aft of the trailing edge of the flaps was displaced to the left and the empennage forward of the horizontal stabilizer was displaced to the right. Aileron and rudder flight control cable continuity was confirmed from each control surface to the control column and rudder pedals respectively. Elevator flight control continuity was confirmed from the control surface to the damaged section in the cockpit area. The flap actuator was measured and the extension equated to 7 degrees. The left flap "up" cable was observed to be failed with signatures consistent with overload failure. The fuel selector handle was broken but the valve was determined to be "on." The aft portion of the left wing fuel tank exhibited evidence of hydraulic deformation and no fuel was observed. The right wing fuel tank was not was observed to be breached and a fuel sample was taken which revealed no evidence of contaminants. The firewall fuel strainer was observed to be impact damaged and fuel and dirt was noted inside the bowl. The strainer screen was observed to be clean. The airplane was not equipped with shoulder harnesses and no determination could be made as to the reason for the reported malfunction of the airspeed indicator. The engine was removed and sent to the manufacturers facility for further examination. Examination of the engine revealed crankshaft and camshaft continuity. Rotation of the crankshaft by hand revealed that the No. 4 cylinder exhaust valve was in the "open" position and would not move. The cylinder was removed and the valve remained in the "open" position. The exhaust valve and valve guide were removed from the cylinder and dimensional measurements were taken of the outside diameter of the valve stem and the inside diameter of the valve guide. The measurements of the guide were taken in two positions; the top and the bottom portion of the guide. The measurements were .434 and .433 inch respectively. The valve stem was measured and found to be .434 inch. The exhaust valve and valve guide were manufactured by Superior Air Parts, Inc., part numbers SA629404 and SA2107 respectively. Examination of the No. 4 cylinder exhaust valve seat and face revealed carbon residue. The remaining exhaust valves also exhibited carbon residue on the faces and seats. There were no other preimpact failure or malfunction noted. TESTS AND RESEARCH Review of the engine overhaul manual revealed that the inside diameter of the exhaust valve guide is required to be a minimum of .003 inch larger than the outside diameter of the exhaust valve stem with new parts. The manual also indicates that when new guides are installed, they are to be reamed to size. ADDITIONAL INFORMATION Weight and balance calculations were performed using the empty weight of the airplane after manufacture (1,055 lbs.) the pilot's weight (265 lbs.) based on his most recent FAA medical examination, full fuel capacity based on a statement from the owner, and the passenger's weight (145 lbs.) based on a statement from him. Also, 1 gallon of fuel usage is calculated to be used for engine start, taxi, and run-up and full engine oil weight of 11 pounds. The calculations indicate that the airplane was about 5 pounds over gross weight at the time of the accident. Performance calculations indicate that at sea level and 59 degrees Fahrenheit, and at gross weight with a 2 knot headwind, the total distance to clear a 50-foot obstacle was 1,315 feet. This is based on a hard surface runway with the flaps retracted. The performance chart does not make an allowance for flap extension. The wreckage with the exception of the retained engine was released to Mr. Bill Brown, the owner of the airplane on October 25, 1996. The retained engine was released also to Mr. Brown, on January 14, 1997.
failure of the pilot to abort the takeoff after encountering excessive ground roll, and failure (or inability) of the pilot to obtain/maintain adequate airspeed, which resulted in an inadvertent stall. Factors relating to the accident were: restricted movement of the No. 4 cylinder exhaust valve, due to improper engine overhaul by the previous owner/mechanic, and failure of the current owner to perform maintenance after being advised by a pilot of excessive rpm drop during a carburetor heat check.
Source: NTSB Aviation Accident Database
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