Hobe Sound, FL, USA
N4100V
CESSNA 150
The pilot departed his home base and flew to a nearby airport for fuel, where he filled the tanks. Afterward, the pilot departed for a cross-country visual flight rules flight. During the takeoff climb, he noticed that “the angle of attack of the airplane was higher than usual and the climb performance was less than expected.” The pilot surmised that the airplane’s reduced performance was a result of the air temperature (about 30°C) and the full fuel load. He continued the flight and recalled monitoring the gauges because the performance of the airplane had him “concerned.” When the airplane was about 48 miles from the departure airport, he determined that the airplane was “losing performance” and that the airplane would not be able to reach an airport. He elected to perform a forced landing to a field. During the landing flare, the airplane stalled and impacted the ground. The pilot was seriously injured, and the airplane sustained substantial damage to the fuselage and wings. A postaccident examination of the airframe and engine revealed no preimpact anomalies that would have precluded normal operation. A review of weather records and airplane performance data indicated the airplane’s expected maximum rate of climb would have been 435 ft per minute or greater at altitudes below 4,000 ft. According to the Federal Aviation Administration’s carburetor icing probability chart, at the surface temperature and dew point during the accident flight, “serious icing at glide power” could be expected. One key symptom of carburetor ice is a reduction in engine rpm, which would result in reduced engine power and climb performance. However, another key symptom of carburetor ice is a roughness in engine operation, which the pilot did not report. He first noticed the decreased performance during the climb, when the engine was likely set for takeoff (full) power. The pilot then determined, while the airplane was flying presumably at a cruise power setting, that the airplane’s performance had decreased such that the airplane would be unable to continue to an airport. Given these presumed power settings along with no reported engine roughness, carburetor icing was likely not a factor in the accident. A review of the airplane’s maintenance records revealed that, at the time of the most recent engine inspection (performed almost 4 months before the accident), the compression test values for some cylinders were lower than during the previous inspection. Significantly reduced cylinder compression results in reduced engine power and decreased airplane performance. However, results between compression tests can occur. Results depend on a number of variables, including ambient and engine temperatures at the time of the tests; therefore, acceptable values are determined at the time of each inspection. No other conditions related to typical concerns with low compression (such as excessive oil consumption, abnormal appearance or condition of oil, or indications of high crankcase pressure) were noted in the airplane’s maintenance log entries during the previous 3 years. The investigation could not determine whether one or more cylinders experienced progressive wear or another condition that might have resulted in deteriorating compression over time.
On September 28, 2021, at 1453 eastern daylight time, a Cessna 150M, N4100V, was substantially damaged when it was involved in an accident in Hobe Sound, Florida. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he performed a preflight inspection with no anomalies noted and then flew 9 nautical miles from his home base at Valkaria Airport (X59), Valkaria, Florida, to Sebastian Airport (X26), Sebastian, Florida, for fuel. After the pilot filled the fuel tanks, the airplane departed X26 for a flight to Witham Field Airport (SUA), Stuart, Florida. During the initial climb, the pilot noticed that the “angle of attack of the aircraft was higher than usual and the climb performance was less than expected.” He surmised that the airplane’s performance was likely due to the heat and full fuel load. The pilot further stated that the “clouds were relatively low so I didn't mind staying low.” He did not recall the route of flight but did recall monitoring the gauges because the performance of the airplane had him “concerned.” When the airplane was about 48 miles away from X26, the pilot determined that the airplane was “losing performance” and that it would not be able to reach an airport. As a result, the pilot initiated a forced landing in an open field. During the landing flare, the airplane stalled and impacted the ground. The airplane came to rest upright in the field with substantial damage to the wings and fuselage. Postaccident examination of the accident site revealed that the right wing was partially separated from the fuselage at its root and was crushed and bent upward and aft outboard of the wing strut. The left wing was damaged near its root, and both pillars forward of the cabin doors were crushed. The aft fuselage was fractured and partially separated just aft of the rear window. Fuel sampled from the right wing tank was blue in color and appeared cloudy. No fuel was present in the left wing. The fuel selector was in the “ON” position. The elevator trim tab actuator length was measured as 1 inch, which corresponded to a tab position of 10° trailing edge down (airplane nose up). A follow-up examination of the wreckage revealed that the engine was mostly undamaged. One propeller blade was bent 90° midspan, and the other propeller was bent and twisted about 10 inches from the tip. No leading-edge gouges or chordwise scratch marks were noted on either blade. The top spark plugs were removed. The electrodes were light gray in color and appeared “worn-normal” compared with the Champion check-a-plug chart. Thumb compression and suction were confirmed on all cylinders when the propeller was rotated by hand. Both magnetos produced sparks on all leads when the input drive shafts were rotated. Fuel sampled from the fuel strainer was blue in color and tested negative for the presence of water. The carburetor had fractured and separated from the intake manifold. The throttle, mixture, and carburetor heat control cables remained attached to their respective control arms. The fuel inlet screen was unobstructed. The bowl was dry and contained a trace amount of debris. The metal float assembly and needle valve/seat were intact. The 1458 weather conditions reported at SUA, located 8 nautical miles north of the accident site at an elevation of 18 ft, included a temperature of 29°C, dew point of 16°C, and a scattered cloud layer at 3,500 ft. The temperatures were within the “serious icing at glide power” portion of the Federal Aviation Administration’s carburetor icing probability chart. A review of the performance section of the airplane’s information manual revealed that, at maximum gross weight and a temperature of 30°C, the airplane’s expected climb performance was 625 ft per minute at sea level and an airspeed of 68 knots and 435 ft per minute at a pressure altitude of 4,000 ft and an airspeed of 65 knots. The engine had accrued a total time of 4,683 hours and 1,167 hours since overhaul. A review of the maintenance records revealed that the most recent inspection of the engine before the accident was a 100-hr inspection performed on June 8, 2021. At that time, the cylinder compression test results for three of the cylinders showed a decrease in compression (reductions of 17, 10, and 8 pounds per square inch [psi]) since the previous inspection; the remaining cylinder had a 6-psi increase in compression. One cylinder’s compression had decreased during previous two consecutive inspections. Cylinder Nos. 1 and 4 had the lowest test value (55 psi). According to a service bulletin from the engine manufacturer, acceptable compression test values vary and are to be determined at the time of the test. No conditions related to low compression (such as excessive oil consumption, abnormal appearance or condition of oil, or indications of high crankcase pressure) were noted in the previous 3 years of the accident airplane’s maintenance records.
A reported loss of engine performance for reasons that could not be determined.
Source: NTSB Aviation Accident Database
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