Incident Details
On July 31, 2017, at about 1745 mountain standard time, a Columbia LC41-550FG airplane, registration N8725, sustained minor damage during an incident near Chandler, Arizona. The private pilot and three passengers were uninjured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a business flight.
The pilot reported that during descent from 9,500 ft mean sea level, the oil pressure indication dropped rapidly, followed by a decrease in manifold pressure. The pilot declared an emergency with the tower controller at Chandler Municipal Airport (CHD) and requested landing clearance. Shortly after, smoke was observed originating from the engine, and the engine began to run extremely rough before losing power. The pilot activated the emergency locator transmitter and initiated a forced landing to a field, resulting in minor damage to the aircraft.
Examination Findings
A Federal Aviation Administration inspector examined the airplane at the accident site. The lower side of the fuselage was covered in oil. The upper engine cowling was removed, revealing a hole 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 showed burned oil deposits across its length. The starter adapter drive pulley was found loose on its shaft. After further disassembly, the pulley hardware (nut and washer) were tight, but the pulley was loose on the starter shaft, allowing it to wobble. The pulley was removed and found damaged; the ball bearing, shaft seal, spacer, and shaft were also damaged. The starter adapter assembly, including aftermarket pulley and belt, was installed directly above the rear exhaust cross-over pipe, which exhibited baked-on engine oil. The engine examination revealed multiple failed connecting rods consistent with oil starvation.
Maintenance History
The Continental Motors Critical Service Bulletin (CSB 02-2C) provides instructions for inspecting starter adapters for oil leakage at the shaft oil seal. The bulletin recommends compliance within the next 10 hours of operation for engines and starter adapters with less than 500 hours total time, and subsequent inspections every 25 hours until 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 showed no indication that CSB 02-2C was complied with or 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.