pitot hardware help

Desert Rat · #1 03-22-2020, 12:02 PM

Hey all-

Garmin Pitot tube calls for #6-32 fasteners about 1/4" long. Nylon patch recommended.

Does anybody know off the top of their head what a good part number and source might be for something like that with a 100 degree countersink and a nylon patch on the threads? Maybe with an Allen head?

If such a creature doesn't exist, my fall back plan will just be some AN507s with red lock tite, unless somebody tells me that's a bad idea on a heated pitot.

Thanks,

Terr

Pilot135pd · #2 03-22-2020, 12:34 PM

Quote:

Originally Posted by Desert Rat

Hey all-

Garmin Pitot tube calls for #6-32 fasteners about 1/4" long. Nylon patch recommended.

Does anybody know off the top of their head what a good part number and source might be for something like that with a 100 degree countersink and a nylon patch on the threads? Maybe with an Allen head?

If such a creature doesn't exist, my fall back plan will just be some AN507s with red lock tite, unless somebody tells me that's a bad idea on a heated pitot.

Thanks,

Terr

I buy my hard to find parts like that locally at a store called ET Fasteners. There should be some kind of store like that in your neck of the woods with another name.

RV7A Flyer · #3 03-22-2020, 03:13 PM

Quote:

Originally Posted by Desert Rat

Hey all-

Garmin Pitot tube calls for #6-32 fasteners about 1/4" long. Nylon patch recommended.

Does anybody know off the top of their head what a good part number and source might be for something like that with a 100 degree countersink and a nylon patch on the threads? Maybe with an Allen head?

If such a creature doesn't exist, my fall back plan will just be some AN507s with red lock tite, unless somebody tells me that's a bad idea on a heated pitot.

Thanks,

Terr

Don't think I'd use red Loctite...you may (will) have to remove it at some point in the future. Blue Loctite should suffice.

mike newall · #4 03-23-2020, 06:37 AM

Just done 2 Dynon pitot's on Gretz mounts and just shortened a#6 screw and used blue Loctite.

Desert Rat · #5 03-23-2020, 08:06 AM

After a little more measuring and head scratching, I see that the wall thickness on the steel mast that I inherited with this project is about .050. The countersink on a AN507 (#6 machine screw) is about .090. In other words, it's a no go with a countersunk #6 unless I can find something with a smaller head i.e shallower countersink.

How are people dealing with this? Just using a pan head screw, shouldered countersink? or what?

PhatRV · #6 03-23-2020, 08:48 AM

I've seen people using pop rivets to hold the pitot tube inside the housing mast. I am thinking of just using the pop-rivet dimpling tool on the mast and use the CS4 pop rivets. This is what I am planning to do in the next few months.

Pilot135pd · #7 03-23-2020, 08:50 AM

I just used round head screws, why do you need to countersink 4 screws? Drag speed loss of 0.0005 knots?

Desert Rat · #8 03-23-2020, 10:15 AM

Yup, pretty much- but I'm about to accept defeat and just use pan head #6 and try to find that .0005 kts somewhere else

Desert Rat · #9 03-23-2020, 10:34 AM

Quote:

Originally Posted by PhatRV

I've seen people using pop rivets to hold the pitot tube inside the housing mast. I am thinking of just using the pop-rivet dimpling tool on the mast and use the CS4 pop rivets. This is what I am planning to do in the next few months.

For me, I see a couple of potential problems with this.

On my setup, the back side of a dimple would prevent the tube base from sliding into the mast. Pretty sure you'd have to countersink it regardless.

Second, my pitot is a garmin and it comes with mounting holes already drilled and tapped for a #6, but the hole is only about 1/4" deep so I don't have a high level of confidence that I could get a rivet short enough to fit in there, that would still swell up enough to fill a #6 hole.

Plus it seems like it would be a bear to get it apart again if the need ever arose.

As I said above, I think I'll likely just give up on this one, use pan head #6's and move on. The other alternative would be to find a flush head fastener that is less than .050 deep, which probably isn't worth the effort at this point.

Pilot135pd · #10 03-23-2020, 10:36 AM

Quote:

Originally Posted by Desert Rat

Yup, pretty much- but I'm about to accept defeat and just use pan head #6 and try to find that .0005 kts somewhere else

Exactly what I did. Use regular screws and move on. Use the time saved searching for and finding other things I can remove to save weight and therefore get more speed with less fuel use.