N3997Y

HISTORY OF FLIGHTOn June 10, 2019, about 1245 Pacific daylight time, a Cessna 210D airplane, N3997Y, was substantially damaged when it was involved in an accident near Ramona, California. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot stated that the airplane had departed from Gillespie Field (SEE), El Cajon, California, and that he was planning to practice a VOR approach to the airport. While the airplane was at an altitude of about 6,000 ft mean sea level (msl), the engine speed increased to above 3,000 rpm. In response, the pilot retarded the propeller control to 2,400 rpm. The pilot thought that the increase in engine rpm was due to a propeller governor anomaly and told an air traffic controller that he was terminating the practice approach and would be returning to SEE. When the airplane was about 5 miles south of Ramona Airport (RMN), Ramona, California, the pilot felt the airplane begin to shake, and he declared an emergency to the RMN air traffic control tower.

The engine lost power, and the airplane touched down in a field about 1/8 mile short of runway 27 at RMN. During the touchdown, the airplane sustained damage to the right wing.

AIRCRAFT INFORMATIONThe overhauled engine was installed in the airplane in June 2003 at an airplane total time of 1,119 hours.

Engine Oil Filter Adapter Design

The engine was equipped with an F&M Enterprises Inc. engine oil filter adapter, model C6LCL, which was installed under Federal Aviation Administration (FAA) Supplemental Type Certificate (STC) SE09356SC. The current STC holder, Stratus Tool Technologies (owned by Aero Accessories Inc.), purchased the STC from F&M Enterprises about 5 years before the accident. The complete certification package for the STC could not be found by the FAA Aircraft Certification Office.

The purpose of the adapter was to enable the engine to use a conventional spin-on oil filter. As manufactured, the oil pump was equipped with a brass oil screen mounted to the casing; the filter adapter used the oil screen bore to attach to the engine. The adapter included a tee casting (housing) and a hub (shaft), which was threaded into the oil screen hole on the engine's oil pump casting. The tee casting had a sleeve with a through-bore and a mounting base that was threaded so that a spin-on oil filter could be attached. A crown (1-inch bolt head) at the outboard end of the shaft secured the tee casting against the oil pump casing. A copper gasket was placed between the crown and the outboard surface of the sleeve's bore; a fiber gasket was placed between the oil pump casting and the inboard surface of the sleeve's bore. Oil inlet and oil outlet passages are provided through the hub and the tee casting to circulate oil from the oil screen hole to the spin-on filter and vice versa (see figure 1).

Figure 1. Oil filter adapter.

The adapter was originally designed to use two AN900-200 copper gaskets. At an unknown time and for an unknown reason, F&M Enterprises changed the gasket between the oil pump casting and the inboard surface of the sleeve’s bore to a fiber gasket. The fiber gasket, part no. FM07, was manufactured from 3750 Leak-Guard material produced by Garlock; the last order that F&M Enterprises placed for the gasket was in July 2013. Stratus Tool Technologies stated that, since the time that it purchased the STC, fiber gaskets have been ordered from Corley Gasket Company, which has not had any FAA oversight.

According to the accident airplane owner, the oil filter adapter was likely installed on the then-newly overhauled engine in June 2003. No documents were found regarding the installation of the adapter, but the adapter was mentioned in logbook entries from March 2004 and January 2007.

STC Holders' Installation Instructions

According to records that Stratus Tool Technologies provided, at the time that the accident oil filter adapter was installed in May 2019, the Instructions for Continued Airworthiness for the oil filter adapter assembly (which had last been published in October 2013) stated, in part, "new gaskets are to be installed anytime the oil filter adapter assy [assembly] is removed and re-installed" and "replace gaskets at 300 hours or 3 yrs whichever occurs first." The Instructions for Continued Airworthiness further stated to "refer to F&M Installation Instructions for gasket P/Ns." The mechanic who performed the most recent maintenance before the accident stated that he replaced the copper gasket and retorqued the filter adapter but did not replace the fiber gasket. At the time of the accident, the fiber gasket was about 42 hours beyond the 300-hour replacement instruction; the airplane had accumulated 17 hours since the time of the most recent maintenance.

In April 2017, Stratus Tool Technologies released a revised oil filter adapter installation manual, which contained a note stating, "the oil filter adapter transfer cylinder must be re-tightened to 65 foot pounds of torque between 8 and 12 hours of operation after installation or any time the adapter is removed and reinstalled." Another note stated, "if the oil filter adapter is loosened, or removed from the engine for any reason, it must be re-installed using new gaskets, tightened in accordance with these installation instructions and properly safety-wired."

Also in April 2017, Stratus Tool Technologies issued Instructions for Continued Airworthiness, which stated that, at each oil change and each 100-hour or annual inspection, the mechanic should "inspect the oil filter adapter for oil seepage" and "if oil seepage is detected, replace the fiber and copper gaskets on the transfer cylinder with new gaskets." The instructions also stated that the "use of a torque wrench is mandatory when installing or reinstalling the filter adapter" and that the mechanic should "safety-wire the transfer cylinder to an appropriate safety-wire location on the engine accessory case"; afterward, the mechanic should "run the engine and check for oil leaks." An additional instruction stated that a mechanic should "check and verify that the body does not move (rotate around the transfer cylinder) when 10 to 20 pounds of force is applied to the body in a manner that would tend to rotate it around the transfer cylinder" and "if the body rotates around the transfer cylinder, remove the safety-wire and tighten the adapter." The instructions further stated to "always install new fiber and copper (where used) gaskets each time the filter adapter is removed and reinstalled on the engine."

AIRPORT INFORMATIONThe overhauled engine was installed in the airplane in June 2003 at an airplane total time of 1,119 hours.

Engine Oil Filter Adapter Design

The engine was equipped with an F&M Enterprises Inc. engine oil filter adapter, model C6LCL, which was installed under Federal Aviation Administration (FAA) Supplemental Type Certificate (STC) SE09356SC. The current STC holder, Stratus Tool Technologies (owned by Aero Accessories Inc.), purchased the STC from F&M Enterprises about 5 years before the accident. The complete certification package for the STC could not be found by the FAA Aircraft Certification Office.

The purpose of the adapter was to enable the engine to use a conventional spin-on oil filter. As manufactured, the oil pump was equipped with a brass oil screen mounted to the casing; the filter adapter used the oil screen bore to attach to the engine. The adapter included a tee casting (housing) and a hub (shaft), which was threaded into the oil screen hole on the engine's oil pump casting. The tee casting had a sleeve with a through-bore and a mounting base that was threaded so that a spin-on oil filter could be attached. A crown (1-inch bolt head) at the outboard end of the shaft secured the tee casting against the oil pump casing. A copper gasket was placed between the crown and the outboard surface of the sleeve's bore; a fiber gasket was placed between the oil pump casting and the inboard surface of the sleeve's bore. Oil inlet and oil outlet passages are provided through the hub and the tee casting to circulate oil from the oil screen hole to the spin-on filter and vice versa (see figure 1).

Figure 1. Oil filter adapter.

The adapter was originally designed to use two AN900-200 copper gaskets. At an unknown time and for an unknown reason, F&M Enterprises changed the gasket between the oil pump casting and the inboard surface of the sleeve’s bore to a fiber gasket. The fiber gasket, part no. FM07, was manufactured from 3750 Leak-Guard material produced by Garlock; the last order that F&M Enterprises placed for the gasket was in July 2013. Stratus Tool Technologies stated that, since the time that it purchased the STC, fiber gaskets have been ordered from Corley Gasket Company, which has not had any FAA oversight.

According to the accident airplane owner, the oil filter adapter was likely installed on the then-newly overhauled engine in June 2003. No documents were found regarding the installation of the adapter, but the adapter was mentioned in logbook entries from March 2004 and January 2007.

STC Holders' Installation Instructions

According to records that Stratus Tool Technologies provided, at the time that the accident oil filter adapter was installed in May 2019, the Instructions for Continued Airworthiness for the oil filter adapter assembly (which had last been published in October 2013) stated, in part, "new gaskets are to be installed anytime the oil filter adapter assy [assembly] is removed and re-installed" and "replace gaskets at 300 hours or 3 yrs whichever occurs first." The Instructions for Continued Airworthiness further stated to "refer to F&M Installation Instructions for gasket P/Ns." The mechanic who performed the most recent maintenance before the accident stated that he replaced the copper gasket and retorqued the filter adapter but did not replac...