Dealing with the gray areas

A few weeks ago, I got an email from a gentleman who was overhauling an antique propeller. He needed to know what lubricant to use in the prop.

The company that manufactured the prop was no longer in business, so all he had was an obsolete spec. I told him I would see what I could find and get back to him.

I first went though my files and found the original spec, but could not find any replacement or document that stated that a particular lubricant replaced the original. I then hit the Internet and called several oil company information centers for a replacement. But no luck.

Next I started calling people I knew who worked in prop shops. The answers varied from “I don’t ever want to see one of those again” to “yes, I have heard of them and I think you use such and such fluid.”

The problem is that the fluids were very different and no one had any documentation that stated that the fluid was a replacement for the original qualified fluid.

After a bit more searching, I called the gentleman back and told him what I had found. I also related back the phone numbers of the people who had experience with these props and had agreed to talk to him.

This is what I call a gray area. What should a mechanic do? Do you tell the pilot that you can’t help him and he may have to let the plane sit, or do you use a product that has been used by others but does not have complete documentation?

If you ask a lawyer or FAA official, the answer is to let the plane sit. But most mechanics like to help people out and hate to see a beautiful old plane sit or be scrapped.

The problem with gray areas is that the legal system only sees things in black and white.

If this plane happened to be involved in an accident, a legal team will go over the history of the aircraft with a fine-tooth comb looking for any gray areas or things that are not completely documented. If they find that a non-qualified lubricant was used in the prop and there are no other major problem, they stop looking.

Then this amazing thing happens: Expert witnesses appear who know everything about this old prop. And they will testify — for a fee — that the use of this unqualified lubricant was definitely the cause of the accident.

Another gray area is compression testing. Most mechanics use a leak down type of compression gauge to determine the condition of each cylinder. This system works well and almost all bad cylinders will fail the test. The problem is that a significant number of good cylinders also fail the test.

Continental now has an alternate method of compliance if your engine fails the first test. Unfortunately, this test is more subjective and open to interpretation. So what happens if an engine fails one test and passes the other and subsequently has an engine failure? Back to the battle of the expert witnesses.

So what does a mechanic do? Unfortunately, a lot of mechanics are just getting out of the business. The other option is discussion and documentation. A mechanic needs to get a customer involved in the decision process whenever a gray area is encountered. Many times they will need to get an outside opinion, usually from a manufacturer’s rep or a real expert.

And then there is documentation. Most mechanics are in the business of fixing things, not doing a lot of paper work. But it is critical in these situations that you get not just an oral agreement, but also a signed written agreement as to the course of repairs and all of the test results that the decision was based on.

It is like going to the bathroom — the job isn’t complete until the paperwork is done.


  1. Chris Hodges says:

    I agree with you on this article. Flying behind an old carburetor may seem archaic to many responders, however, a recent LPM article may be a wake up call to those who think technology in aviation is the answer to making flying better. In the March 2014, LPM an article was written on battery jump starting of a German Diamond DA-42; with an advanced FADEC/ECU system the aircraft was jump started with a dead battery. Shortly after takeoff and gear retraction, the aircraft experienced a FADEC/ECU dual engine shutdown as well as prop feathering. The pilot was able to make an emergency landing and the aircraft was damaged. The problem with advanced systems such as FADEC and more complex flat screens is weight, extra batteries and more powerful alternators to power these systems. This is the very reason why most modern aircraft with these systems today cannot have the same useful load as those simple aircraft in the 40′s. As we follow Europe’s lead in using FADEC, we have to understand the dangers of these systems and the safety issues involved. I for one, like simplicity in aircraft. Kelly Johnson at Lockheed tried to instill simplicity by KISS (Keep It Simple Stupid) and we have not learned a thing.

  2. Mr. Visser:

    You bring up an interesting point, but then fail to answer it. Instead, you and your following commentators take the low road and resort to lawyer-bashing as the root of all evil. I’d like to hear your commentary on lawyers if instead you got ramp checked by the Friendly Aviation Association or a warrantless aircraft search by overzealous ICE or DHS.

    I am in a rather unique position to take exception to your comments, as I am both an A & P, with Inspection Authorization and a practicing Aviation Attorney and Member of the AOPA Defense Panel. With your experience at Shell, you should well know that the answer is to find a suitable substitute for the originally specified lubricant. Shell has always been extremely helpful in these sort of situations and s very pro-aviation. If that fails to resolve the problem, the IA can work with the FAA FSDO in the form of a 337 and document a substitute lubrication procedure, material or subsequent spec with the reasoning therefore. The non-existence or unavailability of the original would be sufficient to justify this.

    Attorneys, much like firearms, can be inherently dangerous and sometimes a real pain in the touchas. But, when you need one; you really need one. Some of us even care about aviation and the people involved in making it happen.


    James D. Lyne, Esq.
    A & P, IA, ATP, CFIAISME & Glider

  3. Glad Mr. Visser mentioned today’s litigious society. That is major part of the problem with today’s G.A. If it wasn’t for the lawyers, it would probably have been a simple matter to just go to different oil companies and research the replacement, then go to the FSDO and see if they would approve the use of some mentioned suitable substitute.
    But, with this legal nightmare, no oil company is even going to talk about some “suitable substitute.”
    Mechanics are generally an easy target for these “ambulance chasers” in such cases, unless they have some of these people on standby themselves, and have written down every single “sneeze” they have received or heard. His comment about turning it back to the owner is only appropriate, as long as everything he did is well documented. C.Y.A. is now a required part of maintenance on anything.

  4. The mechanic should put the obligation back on the owner. While the mechanic (an IA, I presume) is intelligent enough to make a guess, the fact is that the owner/operator of the aircraft has the primary obligation for the maintenance of the aircraft and if the mechanic assumes ANYTHING he is totally liable.
    The mechanic should put the obligation, in writing, to the owner, and await instruction. I can assure you that the FAA would not treat any mechanic nicely is he assumes and uses an incorrect lubricant which may lead to failure. I can quote examples of FSDO inspectors telling me that if a product is out of production then the owner needs to buy a new product, in this case, a replacement propeller for which lubrication is available.
    Yes, I get frustrated with the FAA too – but it’s CYA wherever we look now, and I would not dare to use the wrong lubricant on an assumption that it will work.

  5. Mr. Visser,
    The key, as you stated, is “the original spec.”, it does not matter what is “used” now, what matters is what was it certified with. Again, as you said, the first step is determining what was the original specs for the item, lube. in this case. Many older,antique, aircraft used rather broad specifications as well as many automotive components/materials. After determining the required,and it is required, spec. look to the antique auto suppliers. They have much larger markets and therefore have the ability to have products produced just for them. If the product meets the original spec. for the aircraft,(DOCUMENTED), then it may be used. An example would be Jewell Amber Oil, an equivalent to Mobile Gargoyle “C”, that is usable in many “greaser” engines such as the Warner Scarab. Documentation is paramount, it sadly has become true that the aircraft is not ready to fly until the weight of the paperwork equals the weight of the airplane.

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