The NTSB has issued an Advisory warning airplane owners of a loss of engine power on various Continental engine models linked to F&M Enterprises and Stratus Tool Technologies oil filter adapters.
According to NTSB officials, they identified 11 accidents between 2004 and 2019 in which airplanes equipped with an F&M or Stratus oil filter adapter suffered a loss of engine power following an oil leak. These accidents resulted in three fatalities and five serious injuries.
“As a result, we have issued an advisory to mechanics, airplane owners, and operators,” NTSB officials said. “We also are calling on the Federal Aviation Administration to issue an airworthiness directive to address an unsafe condition associated with oil filter adapters installed through a supplemental type certificate on Continental engines.”
The advisory opens with details of an accident that occurred on May 1, 2019, when a Cessna 182 experienced a total loss of engine power. During the emergency landing, the airplane collided with a power line near Mill Creek, California. One passenger was fatally injured, and the pilot and other passenger were seriously injured.
“NTSB found that the F&M oil filter adapter was loose, a fiber gasket between the airplane’s engine oil pump assembly and the oil filter adapter was torn and had a crescent mark, and oil had leaked from the broken gasket seal (see picture below). The oil leak led to the loss of engine power. We saw at least 10 other airplanes with an F&M or Stratus oil filter adapter that had a loss of engine power following an oil leak, leading to two other fatalities.”
What you can do
Read the NTSB’s safety recommendation report ASR-20-05, which is a deep dive into the NTSB’s investigation, and Stratus mandatory service bulletin SB-001.
“By ensuring that the adapter is installed properly, oil loss and potential engine power loss could be prevented,” NTSB officials conclude.
Is Your Plane Affected?
In the advisory, the NTSB includes a table that highlights the aircraft and engines that are compatible with Stratus and F&M oil filter adapters:
After looking into this I’ve noticed they have changed the installation instructions and ICAW getting rid of the fiber gasket and installing two copper crush washers. The mandatory service bulletin is dated before the new ICAW so I’m thinking that overrides it. The service bulletin still refers to the fiber gasket.
I put one of these F&M adapters on a Cessna 175, GO-300, 8 years ago, and the fiber washer did leak.
I tried another fiber washer and that one pushed out and started leaking oil.
I replaced both gaskets with standard copper-crush gaskets and torqued the sleeve to the spec’d. 65 ft-lb, and no more leaks or movement..
It has 700 hours on it now and I like the filtering and the 50 hr oil change.
After reading the Advisory letter, I’ll add a safety wire from the adapter to the accessory case to prevent any movement that could loosen the nut.
I bought one of these F & M filter adapters a year ago and after seeing it in person, I am mediately returned it even though that meant a 20% restocking fee. The design is terribly flawed as the cast housing which holds the filter rotates freely on the tube shaft that screws into the engine case.
I couldn’t imagine this filter adapter not leaking. After asking several people on beach talk, it turns out many people had the similar situation of this filter adapter seeping oil.