Installing RV engine baffles

[Gilbert Pierce]

McMaster-Carr or a Radio control hobby store has the rods.

[Marc Davis]

If you guys are working on the rods, may I suggest you add a reinforcement to the little tab they go through? That area tends to fail often. I just bent up a little piece of aluminum angle to act as a doubler. That seems to be holding up.

I think the vans baffle kit used 4-40 nuts (MS21042-04). The major diameter of 4-40 is .112. That's a bit smaller than .125, but you may be able to force the threading die on, that's what I did. This might be easer with mild steel than stainless.

5-40 is an odd size. But would fit 1/8" rod perfectly. McMaster does sell 5-40 lock nuts.

[Steve Pierce]

I think I have a drawing. I made them from material from McMaster Carr. Will post the details tomorrow.

[siouxpilot77]

I think I have a drawing. I made them from material from McMaster Carr. Will post the details tomorrow.

Hey Steve. Did you ever find the drawing?

Thanks!!


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[J Ryd]

Here's what I made. I used 6-32" stainless all thread. Both bends on each side are 1" measurements. Fits perfectly with no contact. When installed, the nuts are about 1/2" on each end. I lost about 3/32" overall length (not as much as I thought) before bending.20210303_194704.jpeg

Jan

[Subsonic]

I love (or hate) these ah-ha moments when I read something I wasn't even looking for, and realize that its either missing or not correctly done on Ol Spud. In this case its the baffle rod #14513. As I assemble my cylinder (1960 PA22-150) I see there is nothing between the lower front and rear cylinder baffle. The inner baffles have a little tab with a hole to accommodate the rod (that's missing), but the outermost baffle sections do not? I do have the intercylinder baffles supported by the "S" hook.
Question is, should there be two rods per side? And could these be made with aluminum rode instead of SS?

I don't think I have these lower rods on my plane either...will check today.

[Marc Davis]

Hi,

When an owner modifies a baffle set from an experimental and it's noted as an owner produced part, what prevents an enterprising person from designing a set and selling it for an experimental even though it perfectly fits an old Piper? I'm just wondering if it's really that easy to get around purchasing PMA parts.

Mike Bush (savvy aviation) has a good YT video on the in's and outs of owner produced parts.

[Gilbert Pierce]

I don't think I have these lower rods on my plane either...will check today.

Vans baffles have 4, Piper baffles have 2.

[dgapilot]

Hi,

When an owner modifies a baffle set from an experimental and it's noted as an owner produced part, what prevents an enterprising person from designing a set and selling it for an experimental even though it perfectly fits an old Piper? I'm just wondering if it's really that easy to get around purchasing PMA parts.

A couple things to keep in mind here. For an owner to produce a part for use on a certified aircraft, the first thing is that the part has to conform to the original design, size, shape, material, processes . . . If it doesn't conform to the original design, then it is an alteration, and not an owner produced part. By using a baffle set originally designed for an experimental installation, it no longer conforms to the original design, so no longer fits into the "Owner Produced Part" authorized by 14 CFR 21.9. You have an altered part, and now need to define if it is a Minor Alteration or a Major Alteration. In the case of baffles for the engine, 14 CFR 43 Appendix A is clear that anything that impacts engine cooling system is a Major Alteration, so for all Major Alterations, we know we need Approved Data to install it on a certified aircraft, and a 337 has to be completed. FAA Order 8300.16 identifies the sources of approved data that can be used.

SO in short, to install baffles that don't conform to the original TC (no matter the source) is a Major Alteration that requires Approved Data and a 337.

[dgapilot]

Hi,

When an owner modifies a baffle set from an experimental and it's noted as an owner produced part, what prevents an enterprising person from designing a set and selling it for an experimental even though it perfectly fits an old Piper? I'm just wondering if it's really that easy to get around purchasing PMA parts.

To answer the question about designing and selling for experimental even though it fits perfectly, the text of 14 CFR 21.9 (a) is pretty clear here:

§21.9 Replacement and modification articles.

(a) If a person knows, or should know, that a replacement or modification article is reasonably likely to be installed on a type-certificated product, the person may not produce that article unless it is—
(1) Produced under a type certificate;
(2) Produced under an FAA production approval;
(3) A standard part (such as a nut or bolt) manufactured in compliance with a government or established industry specification;
(4) A commercial part as defined in §21.1 of this part;
(5) Produced by an owner or operator for maintaining or altering that owner or operator's product;
(6) Fabricated by an appropriately rated certificate holder with a quality system, and consumed in the repair or alteration of a product or article in accordance with part 43 of this chapter; or
(7) Produced in any other manner approved by the FAA.

Now, it is done all the time, just look at Wag Aero catalog, there are lots of parts that would fit a certified aircraft, but they have a Code that indicates they are only for installation on non-certified aircraft. What the end user does is up to them. Remember it is the Installer that is responsible for determining the airworthiness of the part that he/she is installing. The problem you are likely to run into, is when an owner installs a part that would not be considered preventive maintenance, that owner is in violation of 14 CFR 43.3, and then the mechanic that does the next (and all subsequent) inspections could be held in violation if the subject part materially contributed to an accident, or if during a ramp check the part were discovered by an inspector.

In short, owners that install parts that aren't certified without the knowledge of their IA are putting that IA at risk of loosing his livelihood and all his assets.