Piper Arrow - what screws needed?

mandm

mandm

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Michael
Does anyone know what type / size screws are used for:

1) Magnetic compass mount to windscreen

2) Cabin door upper latch (on the airframe itself, not the door). P.S. is there a rubber or something I can add to make the upper latch more secure?

3) Interior fabric screws and the washers that secure the fabric to the main cabin door and throughout.

Thank you!
 
Going to the hangar soon to get some pictures of my buddy's arrow so I can work on it later today under supervision from his/my mechanic. I will take peak inside and get some pictures for you if I can.
 
mandm said:
Does anyone know what type / size screws are used for:

1) Magnetic compass mount to windscreen

2) Cabin door upper latch (on the airframe itself, not the door). P.S. is there a rubber or something I can add to make the upper latch more secure?

3) Interior fabric screws and the washers that secure the fabric to the main cabin door and throughout.

Thank you!
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So you are working on the plane without a service and parts manuals?
 
Clip4 said:
So you are working on the plane without a service and parts manuals?
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A lot of owners have never heard of those. I encountered one guy who thought the POH was the only document available. "The manual doesn't even have any information for fixing the airplane!" he said. This was for a 172S. I was pleased to post the links to the service and parts manuals, both of them around 600 pages each.
 
Do you have the old ones? If so, usually easy to figure out the spec. Worst case, visit Ace Hardware, match the dimensions, and then search for a match on the AN specs. Or post a picture here and plenty of people can ID on sight.

If the old ones are not available, and you don't have a parts catalog, you can usually figure it out from the materials being fastened. Look on the backside of the rear piece and see if there is a fastener. If it has a nut plate or rivnut, it takes a machine screw. If it has a tinnerman, it takes a sheet metal screw.

Offhand, I would guess the compass takes a #6 brass instrument screw and brass nut, and the interior trim takes sheet metal screws, possibly stainless or black oxide, probably flat heads with tinnerman or finish washers.
 
Dan Thomas said:
Easy to get fooled there. Many mechanics (and owners) will put the wrong stuff in various places, and subsequent people will copy the mistake.
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Fair point. For something like trim, typically the manufacturer will use the same type fasteners in similar situations. If you find a mismatch, it's often reasonable to deduce from the other fasteners what the correct one is. If an interior panel has 7 sheet metal truss head screws and one machine screw, and the machine screw is going into a tinnerman plate just like the others or has a loose nut on the back, you can conclude that someone down the line just guessed badly. Parts catalog is best of course, but obtaining a parts catalog can sometimes be a challenge for owners who don't have a subscription to the services that professional mechanics have. Until some helpful fellow like you shares a parts catalog, some degree of inference may be necessary for non-structural fasteners.

For structural stuff, owners should be working under supervision and therefore ought to have access to a parts catalog, though there are some circumstances that fall under preventative maintenance, such as changing a tire.
 
IMG_9438.jpeg

I’m thinking it’s #41 / # 42?
 
IMG_9442.jpegIMG_9441.jpegIMG_9440.jpegIMG_9439.jpeg

So the nut is called a tinnerman plate?

The screw is just over 1/2” in length but I’m thinking it’s too long so it’s causing the plate to shift and thus the upper door latch can pop open in flight. Also wondering if the threads are worn down or if that is on purpose. Tried to find the screw at the hardware shop but they don’t screw in smoothly to the tinnerman plate so I have the wrong screw (at the hardware shop). The existing screw goes in smoothly.

The other screw is for something else, I forgot what.
 
I'd call it U nut?
It looks to me that you have some mixed up parts and the screws were damaged by that?
I still am going to the hangar today and will take a peak and post if I think I can help any.
 
Tinnermans are usually used for sheet metal screws. See here for examples. I've seen yours colloquially called a clip nut or U nut, and it is for a machine screw. Since you have the parts catalog, you ought to be able to pull up a spec number. I have seen those nuts for sale at my local Ace hardware and auto parts stores too.

The large screw has been cross threaded badly. Looks to be stainless, which is softer than the nut, which is why the screw got the worse of the wear. Screw looks like a good ol AN526C. Probably an 832 or 1032. Take it to Ace Hardware if you don't have a screw gauge.
 
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