Chandler, AZ, USA
N8725
COLUMBIA AIRCRAFT MFG LC41 550FG
During the flight the pilot reported a loss of oil pressure followed by a decrease in manifold pressure. The pilot declared an emergency and requested landing clearance, however, the engine lost total power and he initiated a forced landing to a field where the airplane sustained minor damage. Postincident examination of the airplane revealed that the lower side of the fuselage was covered in oil and a hole was discovered in the engine’s crankcase. The examination of the engine revealed damage to the starter adapter assembly, which included the starter pulley, bearing, seal, and shaft, that was consistent with the over-tensioning of the accessory belt, which resulted in an excessive side-load. The damaged starter adapter assembly components ultimately resulted in the loss of engine oil and subsequent failure of several connecting rods due to oil starvation. A manufacturer Critical Service Bulletin provided instructions for an inspection of the starter adapter for indications of oil leakage at the shaft oil seal, however, review of the airplane maintenance records show that the service bulletin was not complied with.
On July 31, 2017, about 1745 mountain standard time, a Columbia LC41-550FG airplane, N8725, sustained minor damage when it was involved in an incident near Chandler, Arizona. The private pilot and three passengers were uninjured. The aircraft was operated as a Title 14 Code of Federal Regulations Part 91 business flight. The pilot reported that during the descent from 9,500 ft mean sea level, the oil pressure indication dropped rapidly, followed by a decrease in manifold pressure. He subsequently declared an emergency with the tower controller at Chandler Municipal Airport (CHD), requested landing clearance. The pilot saw smoke originating from the engine, and shortly after the engine began to run extremely rough and then lost power. The pilot activated the emergency locator transmitter and initiated a forced landing to a field that resulted in minor damage. A Federal Aviation Administration inspector conducted an examination of the airplane at the accident site. The lower side of the fuselage was covered in oil. The upper engine cowling was removed, and a hole was visible on the top side of the engine crankcase. The airplane was relocated to a secure facility and the engine was removed from the airframe. The accessory section of the engine was covered in residual oil. The exhaust crossover tube revealed burned oil deposits across its length. The starter adapter drive pulley was found loose on its shaft. After further examination and disassembly of the starter adapter, the pulley hardware (nut and washer) were tight, however, the pulley was found loose on the starter shaft, which allowed the pulley to wobble. The pulley was removed and found to be damaged. The ball bearing, shaft seal, spacer and shaft were also damaged. The starter adapter assembly, including aftermarket pulley and belt were installed directly above the rear exhaust cross-over pipe which exhibited the baked-on engine oil. The examination of the engine revealed multiple failed connecting rods which were found consistent with oil starvation. The Continental Motors Critical Service Bulletin (CSB 02-2C) provides instructions for an inspection of starter adapters for indications of oil leakage at the shaft oil seal. The bulletin states that compliance should be within the next 10 hours of operation for engines and starter adapters with less than 500 hours total time. Additionally, inspect affected engines and starter adapters every 25 hours of operation until accumulation of 500 hours total time. A warning within the bulletin states, “loss of engine lubrication may result in internal engine damage and subsequent engine failure.” The airplane’s maintenance documents provided no indication that CSB 02-2C was complied with or that when the starter adapter drive belt was last adjusted. The last annual inspection was completed on June 21, 2017, and the airplane had accumulated 4.2 hours of operation since that inspection.
The over-tensioning of the accessory belt, which resulted in damage to the starter adapter and subsequent loss of oil that led to oil starvation and catastrophic engine failure.
Source: NTSB Aviation Accident Database
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