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Doug G.

Tire Pressure Monitor

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My last set of tires were not Desser and not Leakguard tubes. The caps were the standard plastic cheapies. The plane was about two years old and the tires were in good shape (the plane had been used mainly on a grass field) my guess is they are original and there is no log entry for replacement. Are you telling me that if I lost one of those plastic caps I would have had to get one from the manufacturer, not Wal-Mart?

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Technically, yes. Would it be silly? Yes. Would anyone really notice or care? Not really.

 

Seriously, don't make me do the whole "wink wink" thing when I say "Technically...".

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This does not fit with what people have spoken of on this site before. I believe it has been said that if there is no part number, and the parts are not in the FD or Rotax (at FDs behest) parts manual (or an SB, or similar) then a reasonable substitute is accepted, no winking needed.

(The external cameras are a different thing.)

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As an aside, I think every aviation tube I've ever installed has come with metal valve caps with o-ring seals.

 

I don't recall ever seeing "plastic cheapie" valve caps on a plane, though that's not to say it does not happen.

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As an aside, I think every aviation tube I've ever installed has come with metal valve caps with o-ring seals.

 

I don't recall ever seeing "plastic cheapie" valve caps on a plane, though that's not to say it does not happen.

Most of the new tubes I get anymore come with plastic caps. This is for LSA and GA aircraft. Aero Classic tubes from Desser.

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Metal caps come with leakguard tubes. If it has an o-ring in the cap, it probably is a metal cap, as it is meant to hold pressure if the schrader fails.

 

This does not fit with what people have spoken of on this site before. I believe it has been said that if there is no part number, and the parts are not in the FD or Rotax (at FDs behest) parts manual (or an SB, or similar) then a reasonable substitute is accepted, no winking needed.

(The external cameras are a different thing.)

As long as you have the specs, and it meets the original part specs at minimum, then you will be fine. Again, I don't think anyone actually cares about a valve cap. But it's that part's specs, and proof that the part meets specs, that is important.

 

To make an example point about replacement parts, you can't pull off a harbor freight special for replacement bolts, even if the specs are equal to the old parts. It's also the paperwork chain integrity that is important. That's why a lot of aircraft hardware comes with 8130's. It is a testament that the hardware IS what the package says it is, and there has been control over the manufacture and logistics of the hardware. And, if there is a problem with the hardware, it is traceable to the origin.

 

Why are 8130's important? There was, and still is, a serious problem with hardware not meeting spec. Aircraft parts and hardware were particularly bad in the 70's and 80's. There was a guy on 60 minutes talking about how he ran counterfeit aircraft parts across the border from mexico, and made more money than the drug cartels. These days, 8130's have greatly lessened the problem, and act as due diligence to CYA if something happens.

 

I know it is just a valve cap. I agree this conversation is silly. But if I were to ever use any parts from walmart, even those as innocuous as a valve stem cap, I certainly would not announce it on a public forum, especially with identifiable information in my signature :P.

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I have never seen a 8130 tag for a SLSA part. In fact since they can use parts that don't meet FAA standards I think the only thing we have to go by is that the part meets the specification set forth by the manufacturer. Where you buy parts from doesn't mean anything, it is that they meet the specification. I have bought parts for the CT at Walmart before, and have no problem stating so.

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That's specifically why I pointed out hardware as the example in certificated aircraft. The point of my example was traceability and CYA, not about having to get 8130's with your LSA parts. If you order parts from FDUSA, you have the invoice as proof that you did your due diligence, and your ass is covered. At the same time, I also keep saying, I get it, it's a simple valve cap. Technically (WINK WINK!!!) you are supposed to obtain parts from either FDUSA, or where they say you can get them. If I saw someone put a walmart brand valve cap on their tube, I wouldn't care, even on a standard aircraft. But, I wouldn't post about it on a public forum. If an accident happens and you have several posts about getting parts from harbor freight, or walmart, or sears, the investigators might start asking questions about other parts in the plane, important parts that you probably DO get from reliable sources, but might not still have the paperwork for it!

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I didn't see where you said hardware in certified aircraft. The way I see it some parts have to come from Flight Design, but if they provide a specification and size or an outside manufacturer part number you can get it from another source. I know in the past Flight design USA has purchased parts locally and provided them to customers. In at least one case I was not happy with the substitute part.

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I shouldn't have needed to say standard aircraft, as it's implied when it comes to 8130s. It's also why i said a lot of aircraft hardware (not all) comes with said 8130's.

 

As for flight design buying locally: that's the manufacturer. They are allowed to do that with standard aircraft too. Piper used to list part equivalents in their parts catalogs for things like air filters, because they would buy car air filters and rebrand them. If the part failed though, guess who got the FAA heat? The manufacturer!

 

As a side note, you as a mechanic can also buy materials to use in the production of a part for an aircraft. But, if that part fails, you get the heat. In standard aircraft for example, you can't buy non-tso or non-pma parts, but you can build them. The important part there is whether or not the part is being sold, or if it's being produced in the process of maintaining the aircraft. That said, if you ever build a part, you need to have your documentation in order showing that what you are building is better or equal to the original.

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I'm sorry, but you brought up the part about 8130's for hardware in a conversation about light sport aircraft. Not everyone here understands that they have nothing to do with an SLSA.

 

Flight Design USA is not the manufacturer they are the US importer of the aircraft, so your parallel with other aircraft manufacturers doesn't hold water.

 

Whether or not a mechanic can make parts is a can of worms I don't want to open.

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Flight Design USA has access to a lot of technical and manufacturing documentation that FD Germany has given them. In addition, FD Germany has given FDUSA some degree of autonomy over parts sourcing and maintenance procedures, and they are getting more and more as manufacturing opens up in Vermont. If it requires engineering, however, it still needs FD Germany's involvement. FD USA is allowed to source parts locally, and therefore, yes, my parallel DOES apply, as they are acting on behalf of the manufacturer.

 

From a regulatory and liability standpoint: let's say that FDUSA sells a part that they bought locally that FD Germany did NOT allow them to. How would you tell the difference? You as the mechanic will likely not be able to. But, if something happens, the NTSB will follow the paper trail back to the source, and FDUSA would get in deep with the FAA. You, as the mechanic though, have done your due diligence. You have invoices that states that you bought the part from FDUSA. You have done nothing willfully negligent, and bought from a known reliable parts provider approved by the manufacturer. You would have done everything reasonably possible to ensure the part is safe for use.

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Checked with Dave Armando. He said there is no issue with the tire pressure monitors.

 

Then you are covered :).

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Just for clarification the tire pressure monitor caps do screw on and do have seals. (Otherwise, of course, they would not be able to read the pressure.)

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