History of Flight
On June 10, 2019, about 1245 Pacific daylight time, a Cessna 210D airplane, N3997Y, was substantially damaged during an accident near Ramona, California. The pilot and passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight. The pilot reported that after departing from Gillespie Field (SEE) in El Cajon, California, to practice a VOR approach, the engine speed increased above 3,000 rpm while at about 6,000 ft msl. The pilot reduced propeller speed to 2,400 rpm and believed the anomaly was due to the propeller governor. He informed air traffic control that he would return to SEE. About 5 miles south of Ramona Airport (RMN), the airplane began to shake, and the pilot declared an emergency. The engine lost power, and the airplane landed in a field about 1/8 mile short of runway 27, sustaining damage to the right wing.
Aircraft Information
The overhauled engine was installed in June 2003 at an airplane total time of 1,119 hours. The engine was equipped with an F&M Enterprises Inc. engine oil filter adapter, model C6LC-L, installed under FAA Supplemental Type Certificate SE09356SC. Stratus Tool Technologies (owned by Aero Accessories Inc.) was the current STC holder. The adapter allowed use of a spin-on oil filter. Its design included a tee casting and a hub threaded into the oil pump casting's oil screen hole. Original design used two copper gaskets; at an unknown time, F&M Enterprises changed the inboard gasket to a fiber gasket (part no. FM07). The fiber gasket was manufactured from 3750 Leak-Guard material by Garlock, with the last order by F&M Enterprises in July 2013. Stratus Tool Technologies noted that fiber gaskets were later ordered from Corley Gasket Company without FAA oversight. No installation documents existed, but logbook entries from March 2004 and January 2007 mentioned the adapter. According to Stratus Tool Technologies records, the Instructions for Continued Airworthiness (published October 2013) required gasket replacement whenever the adapter was removed or reinstalled, and replacement every 300 hours or 3 years. The mechanic performing maintenance before the accident replaced the copper gasket and retorqued the adapter but did not replace the fiber gasket. At accident time, the fiber gasket was about 42 hours beyond the 300-hour replacement interval, and the airplane had flown 17 hours since maintenance.
Wreckage and Impact Information
Postaccident examination revealed engine oil coating the airplane's belly and holes in the crankcase. The filter adapter was loose, and its housing could be rotated about the shaft. The crown head and oil filter screen bolt head remained safety wired. Oil was concentrated near the adapter and adjacent firewall. The hub nut had wear marks consistent with tool slippage. A zip tie around the adapter arm, holding two wires, was positioned near the nut, obstructing installation and removal. The fiber gasket protruded beyond the castings and had a tear where the housing abutted the engine case. Breakaway torque of the adapter was 9 ft-lbs. Removal showed the fiber gasket had torn and contained lips with a crescent impression. The copper gasket was intact. Testing on an exemplar gasket showed that insufficient torque (below 65 ft-lbs) allowed housing movement and oil leakage. When properly torqued to 65 ft-lbs, manual rotation of the housing could still create a crescent impression similar to the accident gasket, but investigators could not replicate the tear.
Additional Information
A review of NTSB data found at least six previous oil starvation events (2009-2019) involving F&M Enterprises/Stratus Tool Technologies oil filter adapters due to gasket failure or improper installation. In response, Stratus Tool Technologies issued mandatory Service Bulletin SB-001 on October 25, 2019, directing inspection for oil leakage and gasket damage, and providing proper installation instructions. The bulletin noted discontinuation of fiber gaskets: only copper gaskets were approved for initial or reinstallation. The FAA issued Airworthiness Directive 2022-04-04, effective March 29, 2022, requiring removal of fiber gaskets and replacement with copper gaskets due to the risk of engine power loss from oil starvation.