History of Flight
On May 31, 2011, at approximately 0845 central daylight time, a Cessna 150F, registration N7818F, impacted a sign and a tree during initial climb following a loss of climb performance. The departure was from Sully Municipal Airport (8C2), Sully, Iowa, and the intended destination was Pella Municipal Airport (PEA), Pella, Iowa. The airline transport pilot and the one passenger were uninjured. The airplane sustained substantial damage to the left wing, fuselage, and left horizontal stabilizer. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed and no flight plan was filed.
The pilot reported that the preflight and engine run-up revealed no abnormalities. Flaps were set to 10 degrees for takeoff on runway 8, a turf runway measuring 2,130 feet by 120 feet. After a ground roll of approximately 700 feet, the airplane lifted off and was flown in ground effect until the end of the runway, where it yawed left about 20 degrees. The airplane then contacted the ground, departed the runway end, and struck a sign and a tree. The pilot stated that he assumed a safe departure was possible based on the airplane's performance charts.
Aircraft Information
The accident aircraft was a 1966 Cessna 150F powered by a Continental O-200-A engine (serial number 63047-6-A) equipped with a McCauley 1A100 propeller. The maximum gross weight of the Cessna 150F is 1,600 lbs; the pilot reported an accident weight of 1,521 lbs. The last major engine overhaul occurred on May 1, 1974. An Engine Components Inc. cylinder assembly (part number 641916 CP, serial number 04) was installed during a top overhaul in 1993, at which time the airplane total time was 3,601 hours and engine time since major overhaul (SMOH) was 1,300 hours. No records indicated that the pistons had been replaced since the major overhaul or at the top overhaul. The last annual inspection was on March 14, 2011, showing a total time of 3,782.7 hours and 1,485.8 hours SMOH.
Teledyne Continental Service Information Letter SIL98-9A recommends that engines be overhauled at least every 12 years. McCauley Service Bulletin SB137AE states that fixed-pitch propellers should be overhauled at 2,000 hours or 72 calendar months, whichever occurs first, and that propeller mounting bolts must be inspected or replaced at specified intervals.
The 1966 Cessna 150 Owner's Manual takeoff performance section provides distances for flaps-retracted operations on hard surface runways. For a gross weight of 1,600 lbs, 0 knot headwind, at sea level and 59°F, ground run is 735 feet and total distance to clear a 50-foot obstacle is 1,385 feet. At 2,500 feet and 50°F, ground run is 910 feet and total distance to clear a 50-foot obstacle is 1,660 feet. The pilot noted in his recommendation that the performance charts do not account for an engine with 1,485 hours SMOH or a 45-year-old propeller with 3,782 hours total time.
Meteorological Information
The pilot reported winds from 150 degrees at 12 to 15 knots. A witness who had landed on runway 26 at 8C2 stated there was a strong crosswind from the south around 0830. The witness observed a Decathlon that departed runway 8 and was crabbing at least 30 degrees into a right crosswind from the south. Weather observations from nearby airports at 0835 included: Newton Municipal Airport (TNU) – wind 190° at 8 knots, temperature 20°C, dew point 18°C, altimeter 29.94 inHg; Grinnell Regional Airport (GGI) – wind 180° at 10 knots, temperature 21°C, dew point 18°C, altimeter 29.94 inHg; Pella Municipal Airport (PEA) – wind 210° at 6 knots, temperature 19°C, dew point 17°C, altimeter 29.93 inHg. Relative humidities computed from these data were approximately 88.3% at TNU, 83.0% at GGI, and 88.2% at PEA.
Wreckage and Impact Information
The Pella airport manager reported that the runway grass was slightly long but not over 6 inches, and the surface was smooth with no rough or soft spots. He observed tracks from the takeoff roll that disappeared near midfield (either due to the airplane being airborne or light on its wheels) and then two tracks reappeared approximately 100 to 150 feet from the runway end, veering left across a road and into a residential property. The airport manager confirmed flight control continuity of the airplane prior to its recovery. About 12 gallons of fuel were drained from the airplane.
Disassembly of the engine by a mechanic revealed that the number four cylinder rings were fractured.
Tests and Research
Examination of the cylinder assembly and piston was performed by the National Transportation Safety Board Materials Laboratory. The cylinder appeared intact with a smooth bore and a longitudinal mark that could not be felt. The base flange was painted orange, indicating a chromium-plated bore. Hardness and gradient were consistent with continued aging of the aluminum alloy during operation. The piston was intact with no cracks or erosion. The piston had three solid compression rings; the first (top) ring was broken into many pieces, the second (middle) ring was broken into two pieces, and the third compression ring and oil control ring were intact. Magnified optical inspection of the ring fractures revealed mechanical rubbing and damage that almost completely obliterated fracture features. Optical examination showed extensive widening of the first piston ring slot, completely around the piston but much wider in one quadrant, wide enough to accommodate two fractured pieces of the ring. The second ring slot also showed widening. Pieces of the first and second rings appeared deformed with flared cylinder contact faces, a flaring that was not due to deformation but selective material removal from the inboard and outboard faces of the ring slots. Hardness measurements on the piston cross section ranged from 75.7 to 82.6 Brinell Hardness (HB), with softer material adjacent to the piston crown and harder material at the wrist pin boss. As manufactured, a minimum of approximately 98 HB is required.
The pilot stated that after the accident, he would not depart from 2,100-foot runways with a road at the end and no clear zone or overrun area.
Additional Information
FAA publications note that pilots should ensure runway length equals the manufacturer's published takeoff or landing distance plus an 80% safety margin for hard surfaces, and double the manual distance for sod. Additionally, high humidity may warrant adding 10% to computed takeoff distance and anticipating a reduced climb rate.