Manistee, MI, USA
N2056R
CESSNA 182G
The private pilot was in cruise flight about 2,500 ft mean sea level during a cross-country flight when he noted an engine vibration and loss of power, which he could not remediate. The pilot performed a forced landing to a field, during which the airplane nosed over. Postaccident examination of the engine revealed no mechanical anomalies that would have precluded normal operation. One of the two propeller blades was rotated about 90° and was beyond its high pitch limit. The high pitch angle of the blade would have resulted in high drag and/or loss of propulsive thrust. Disassembly and metallurgical examination of the hub of the rotated propeller revealed that its blade actuating pin had fractured in high-cycle fatigue. According to a manufacturer's service bulletin, the propeller should be overhauled at 1,500 hours or 60 calendar months, whichever occurs first. Propeller logbooks showed that the accident propeller was last overhauled nearly 24 years and over 1,592 hours before the accident. It is likely that compliance with the manufacturer's recommended overhaul schedule would have resulted in the fatigued pin being replaced.
On April 23, 2017, at 1125 eastern daylight time, a Cessna 182G airplane, N2056R, experienced a loss of propeller blade pitch control during cruise flight. The pilot performed a forced landing to a field about 6 miles south-southwest of Manistee, Michigan, where the airplane nosed-over and impacted terrain. The airplane sustained substantial damage. The private pilot and three passengers received minor injuries. The airplane was registered to and operated by the pilot under 14 Code of Federal Regulations Part 91 as a personal flight that was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The flight originated from Albert J Lindberg Airport (5Y1), Hessel, Michigan, at 1010 and was destined to Hastings Airport (9D9), Hastings, Michigan. The pilot stated that he arrived at 5Y1 about 0915 and performed a preflight of the airplane, which included inspecting the propeller. During the pre-takeoff airplane runup, he cycled the propeller three times, and the propeller functioned without anomaly. The departure weather for the flight from 5Y1 to 9D9 had an overcast layer of 3,000 ft mean sea level and a visibility greater than 10 miles. The overcast layer diminished to clear skies as the flight progressed southbound at 2,500 ft mean sea level along the Lake Michigan shoreline to the Cross Village, Michigan. After passing Manistee, Michigan, there was a "sudden" noise from the engine, an "instant" engine power loss, and a "heavy but steady vibration". The pilot stated the he did not have time to check the cockpit [configuration/selections] but did cycle the throttle, which resulted in no change in noise level or engine power. The pilot stated that he did not shut down the engine. He performed a forced landing to a field. During the right base leg to the field, the pilot saw powerlines and felt it unsafe to turn onto a final approach leg due to the airplane altitude, so he continued to land straight ahead. The airplane touched down with a "full" stall warning horn sounding and "immediately" nosed-over. A download of a J.P. Instruments engine data monitoring device showed that engine speed during approximately the last 1:50 minutes of the flight decreased to a range of 1,157 – 1,899 rpm. The airplane had installations of a Continental Motors O-470-R, serial number 130002-3-R-4, engine and a 1978 manufactured McCauley C66, model number D2A34C66-NP/E-S-90AT-8, serial number 787633, propeller that had a threaded blade retention. This C66 model was first certified in June of 1964. This type of propeller (and supporting spares) is obsolete and no longer produced by McCauley. Post-accident examination of the engine by the National Transportation Safety Board (NTSB) Investigator-In-Charge (IIC) and a Continental Motors representative revealed no mechanical anomalies that would have precluded normal operation. One of the two propeller blades was rotated about 90 degrees and was beyond its high pitch limits. Both propeller blades exhibited bending, twisting, paint scuffing, leading edge impacts, and overall propeller assembly damage is typical of that associated with low-level torsion at impact. The propeller was removed from the engine and sent to McCauley for disassembly and metallurgical examinations under the supervision of the NTSB IIC. Both propeller blades were manufactured before 1976 and had the following serial numbers: blade 1 - K96493YS, blade 2 - K96462YS. The last propeller overhaul occurred prior to installation on the airplane on June 7, 1993 (23 years and 10 months prior to the accident). The last propeller logbook entry was dated March 27, 2017 (approximately one month prior to the accident) and indicated a time since overhaul of 1,592.12 hours. The McCauley overhaul intervals of the C66 model propeller is cited in Service Bulletin SB137AF. The revision in effect at last recorded overhaul (SB137E) of the accident propeller and all subsequent revisions of SB137 have consistently recommended propeller overhaul at 1,500 hours or 60 calendar months, whichever occurs first. The propeller examination revealed that the propeller had indications of several post-delivery field service events including multiple ferrule drill holes, and red oil fill modification per McCauley Service Bulletin SB152A. The blade 1 actuating pin did not display damage or cracks. Blade 2 had a broken actuating pin (A-3149), which had indications that the pin failed in high cycle fatigue prior to impact. The pin material, hardness, and the combination cadmium and chrome plate finish was consistent with a pin manufactured sometime between start of production and May 1965. The pin material, and manufacturing methods were correct and compliant to the engineering requirements at time of production.
The failure of the airplane owner and maintenance personnel to follow the propeller manufacturer's recommend overhaul schedule, which resulted in a fatigue fracture of the propeller blade actuating pin and a loss of thrust in flight.
Source: NTSB Aviation Accident Database
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