Leading edge screws
- Thread starter redfin
- Start date
bob turner
Registered User
I think they are all 4x1/4, but the ones that go in the spar are "B". Think of that B as "blunt end."
Piper, way back when, had really shallow slotted head PK screws. If you can find them, your fabric bumps will be less obvious.
If you are starting with a new spar, I recommend pre-tapping the holes. I used a 1/4x3/8, gripped in small Visegrips. Tap ten holes, then get a new screw. They are hardened, and if they break off in the spar you get to re-locate the hole.
Piper, way back when, had really shallow slotted head PK screws. If you can find them, your fabric bumps will be less obvious.
If you are starting with a new spar, I recommend pre-tapping the holes. I used a 1/4x3/8, gripped in small Visegrips. Tap ten holes, then get a new screw. They are hardened, and if they break off in the spar you get to re-locate the hole.
Steve Pierce
BENEFACTOR
Graham, TX
I use the #4x1/4 from Spruce on skin to ribs and get the screws from Dakota Cub for ribs to spar and skin the spar. That is how Piper did it and it works.
bob turner
Registered User
I rather suspect Piper got their screws from Parker-Kalon. Spruce really didn't get started until rag wing production had stopped.
I would order THA4-4 for leading edge to rib, and THB4X4 for spar attach, from Spruce or Genuine. The 4-4 is a slotted head, and looks like the Piper originals from the picture.
I would order THA4-4 for leading edge to rib, and THB4X4 for spar attach, from Spruce or Genuine. The 4-4 is a slotted head, and looks like the Piper originals from the picture.
bob turner
Registered User
4-40. I hate to say it, but Piper probably got them in bulk at the local hardware store. You can get better steel from Micro Fasteners, but I have never seen one break. Lots stronger than the cap strip.
Steve Pierce
BENEFACTOR
Graham, TX
I use MS35206-215 and -216 if memory serves me correctly. Started getting split lock washers at the hardware store when I could find the AN version anymore, several years ago.
https://www.aircraftspruce.com/catalog/hapages/ms35206.php?clickkey=6563645
https://www.aircraftspruce.com/catalog/hapages/ms35206.php?clickkey=6563645
KJC
FRIEND
Clear Lake, MN
If it’s certified, then yes you do. It’s easy to rivet in, and provides the proper location for the cutouts for the hinge and pushrod. Additionally, it strengthens the false spar where most of the load is imposed during flap extension. If you having trouble riveting it in, then machines screws, washers and locknuts would be an acceptable alternative. Make sure the nuts are on the inside.
Its hard to tell but it looks like your splicing in a new section of false spar on the inboard side of the wing? If that’s the case, then you should just use an entire new section. If I’m wrong on that then disregard.
Its hard to tell but it looks like your splicing in a new section of false spar on the inboard side of the wing? If that’s the case, then you should just use an entire new section. If I’m wrong on that then disregard.
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