Engine Making Metal

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“I’ll be having the annual inspection of my 1998 Cessna 182 done at Caviar Aviation this year,” Ted advised his Savvy account manager Tom Cooper A&P/IA. “George is the Director of Maintenance (DOM) there, and I spoke with him to schedule my annual for the week between Christmas and New Years Day.”

Tom scratched his head. Normally, SavvyMx clients have their Savvy account managers schedule their service appointments and deal with the shops and mechanics. And scheduling an annual inspection for the short week between Christmas and New Years Day seemed a bit optimistic. Tom doubted it could be completed during that week unless it was a very cursory inspection indeed.

In order to clarify what Ted’s expectations were, Tom explained to him that there were two alternative ways for Ted to proceed:

  1. Maintenance Management: Ted would authorize Savvy to contact the shop, and have all communications with the shop come from Savvy; Savvy would be acting as Ted’s maintenance manager and representing his interests throughout the annual.
  2. Maintenance Consulting: Ted would handle all communications with the shop, and Savvy will remain in the background to answer any questions and provide any needed second opinions.

Clients who enroll in SavvyMx almost always choose the first approach.

“Tom, for this year’s annual, I will go with plan number two,” Ted said.

“Okay, that works. Thanks for clarifying,” said Tom.

“The annual should start on December 28th,” said Ted.

Change of Plans

On December 28th, Tom checked in with Ted to find out if the annual inspection started on schedule and if he needed anything from Tom.

“Tom, it did start today, and I will need your help,” said Ted. “George from Caviar Aviation just called to tell me that he has found metal in the oil filter and it is magnetic. He took some pictures that I am attaching.”

 “George suggested that he stop work on the annual because he felt the engine would need to be sent out to an engine shop for a teardown. I told him that I would ask Savvy to talk with him directly. So, he is expecting to hear from you.”

“I did fly the plane up from Atlanta about a week ago,” Ted continued, “and everything seemed just fine, so this comes as a shock.”

“No problem,” Tom said.

Savvy Takes the Con

“Good afternoon, George,” Tom said to the DOM. “Ted gave me a few photos showing the metal you found in the oil filter, and that you apparently told him were magnetic. As you probably know, Continental Motors provides no written guidance as to how to respond to metal in the oil filter. However, Lycoming offers extremely detailed guidance in its Service Bulletin No. 480F, and in Savvy’s opinion this guidance offers a reasonable decision framework for Continental engines, too.”

Tom explained that the Lycoming guidance is quite voluminous, but the CliffsNotes version is:

  • Less than 10 pieces of metal 1/16-inch diameter or less: Continue to fly until the next regularly scheduled oil change.
  • Between 10 and 20 pieces of metal 1/16-inch diameter or less: Fly for 25 hours and reinspect.
  • Between 20 and 40 pieces of metal: Operate the engine on the ground for 20-30 minutes, then cut open and inspect the oil filter. If the oil filter is clean, fly for 10 hours and reinspect.
  • More than 40 pieces of ferrous metal or more than 1/4 teaspoon of non-ferrous metal: Start taking the engine apart.
  • More than 1/2 teaspoon of metal: Tear down the engine.

Tom told George that Savvy recommended the following two additional actions before doing anything else to Ted’s engine:

  1. Remove the propeller governor from the engine and inspect the prop governor gasket screen to determine whether any of the metal got past the oil filter and into the engine’s oil galleries.
  2. Send the contents of the oil filter to Aviation Laboratories in Houston for scanning electron microscope (SEM) “chip kit” analysis to determine the exact composition of the filter contents.

Tom put this all in writing, then followed up with George by telephone to make sure they were on the same page. It seemed as if they were. The next day, George sent a message to Tom:

“I washed the oil filter element and found some more debris, seemed to be rust and particles. I pulled the propeller governor and did not find anything in the gasket screen. At this time, I am pulling the drain from the oil sump. I am going to use a magnet and borescope to see how much has accumulated in the sump and look at the suction screen at the bottom of the oil pickup tube. I will likely pull the alternator to inspect the drive gear and coupling. I will keep you posted.”

“That’s great news that the prop governor gasket screen is clean. This means that the metal was stopped at the oil filter. But why are you pulling the alternator? We would like you to wait until you get the report back from Aviation Laboratories before taking anything apart. The AvLab report may tell us where the metal is coming from.”

“We could send the filter element, along with what came out of it, to a lab but it will take a couple of weeks to get an answer. I have a call into my engine shop to get their opinion. At this point, however, I would not put my family or myself in this airplane with this engine in its current condition.”

It was obvious to Tom that George had already made up his mind that the engine should be torn down, and wasn’t interested in obtaining more data or following the measured approach recommended by Lycoming SB 340F. This could get interesting.

“George, we are requesting that you STOP ALL WORK on Ted’s engine until the filter contents have been sent to Aviation Laboratories for analysis and their report has been received,” Tom said with atypical bluntness. “Please overnight the filter contents to them, and let us know as soon as you get the report.”

What the Report Said


Aerospace Material Specification (AMS) 4280 is aluminum alloy used in castings. The lab found no evidence of ferrous metal in the filter contents that George sent them. However, George was unconvinced:

“I sent them a big chunk of steel and they said all they found was aluminum,” George told Tom. “That is why I don’t use AvLab.”


At Ted’s request, George had also sent off an oil sample to Blackstone Laboratories for spectrographic analysis. Their report said:

“Not much has changed since the last sample. Metals are down slightly since the October report, which is good news.”

What Should Ted Do?

“Ted, I asked the entire Savvy team to review your situation,” Tom said. “The consensus opinion was that you should run the engine on the ground for 20 to 30 minutes and check the oil filter. If the filter comes up clean, then fly the plane for an hour or two and check the filter again. If it comes up clean again, then continue to fly for 10 hours and check again. If it’s still clean, you can relax knowing that you dodged the bullet.”

“Of course, you have to do whatever lets you sleep well at night,” Tom added. “I would expect the engine shop and the engine manufacturer to recommend tearing down the engine—their primary concern is limiting their liability. If it was my engine, I sure wouldn’t be in a hurry to tear it down.”

“Tom, I like your approach,” replied Ted. “I’ll certainly do the 20-30 minute ground run. Then we’ll have to see if we can persuade George to sign off the annual as airworthy so I can fly it for an hour or two in the vicinity of the airport. It will be interesting to hear what Continental and George’s engine shop have to say…”

It was clearly going to be a challenge to bring George around to Tom’s and Ted’s plan of attack. At Ted’s request, Tom scheduled a three-way phone call with George and Ted. Ted figured that George would be more inclined to listen to a fellow A&P/IA than to a lowly aircraft owner.

Tom is a pretty persuasive guy. By the end of the phone call, George reluctantly agreed to the plan.

The Outcome

To make a long story short, Ted performed the ground run. The filter came up clean. Ted then flew the plane for a couple of hours. The filter came up clean again. Ted flew for 10 more hours. Still no metal in the filter. The bullet was dodged.

The invoice that Ted received from Caviar Aviation came to $2,650. Tom told Ted that he considered it very fair. It probably would have been at least $30,000 more if George had done what he wanted to do.

“Tom, I’m so very grateful for your help with this annual inspection,” said Ted just prior to closing out his ticket. “You guys should use it in one of your weekly stories where you show how Savvy can save aircraft owners gobs of dough.”

And so we did.

Ted had used Caviar Aviation for an earlier annual inspection. It went smoothly and Ted had come to trust George. But when a little aluminum showed up in the oil filter, George panicked and was spring-loaded to the teardown position instead of adopting the measured data-driven approach of Lycoming SB 340F that Savvy uses as its bible in such situations. He even resorted to scare tactics with Ted (“I would not put my family or myself in this airplane…”)—we really hate it when mechanics do that to our clients.  George’s reaction and Ted’s predicament aren’t unusual. We deal with this sort of thing all the time.

If you’re an aircraft owner, you never know when a situation like this might happen to you. If it ever does, you’ll be awfully glad that you were smart enough to have enrolled your aircraft in the SavvyMx program and have an account manager like Tom looking out for your best interests. At $750 per year for a piston single like Ted’s Skylane, it’s cheap insurance against an unwarranted $30,000 surprise (or maybe worse).

You bought a plane to fly it, not stress over maintenance.

At Savvy Aviation, we believe you shouldn’t have to navigate the complexities of aircraft maintenance alone. And you definitely shouldn’t be surprised when your shop’s invoice arrives.

Savvy Aviation isn’t a maintenance shop – we empower you with the knowledge and expert consultation you need to be in control of your own maintenance events – so your shop takes directives (not gives them). Whatever your maintenance needs, Savvy has a perfect plan for you: