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Skybolt fastener question

S

Stockmanreef

Well Known Member
I accidentally bought the kit with slotted collar studs instead of the phillips studs. Does anyone else have the collared slotted? Or should I just exchange them? Would the stud for s flat head screw driver just be annoying?

thanks
ken
 
annoying

It would be annoying when the straight slot driver slides out of the sky bolt and puts a chip or scratch in your beautiful paint job...
 
slotted v. phillips

I have the slotted and I like them better than the phillips. Of course, if they could make a torx version, it would be even better.

Just get a really good screwdriver with the exact size of the slot, and take care when working with them and it should be fine. I have a "grease" screwdriver that has only been used on my skybolts, and so far, no scratches, but I'm very early in my experience with them.
 
YES

I agree 100%.

A Torx version would be perfect.

I am currently sourcing tori drive screws for all of my inspection panels. They are available but to get the 100 degree FH screws you either have to buy a carton (5000) or the price goes way, way up...
 
We use a lot of slotted ones on our ag planes. The sky bolt ones are better than the cam lock ones due to the boxed in shape of the slot, but if you want to protect your paint long term, I?d see if they would let you swap them out.
 
I've had the slotted ones on my rv8 cowl for 5+ years and happy with them, haven't had any issues with the screwdriver slipping. Also makes it easy to see they're all secured in the correct orientation.
 
A buddy of mine uses the slotted ones simply because if he needs to open something and doesn?t have a screwdriver. He?ll use a dime if he has to. I disagree. If I have to hunt down a screwdriver rather than messing up my paint, I?ll do that. Of course, I haven?t painted my plane yet either, but whatever.
 
Torx

rocketman1988 said:
I agree 100%.

A Torx version would be perfect.

I am currently sourcing tori drive screws for all of my inspection panels. They are available but to get the 100 degree FH screws you either have to buy a carton (5000) or the price goes way, way up...
Click to expand...
If you are ok with stainless, these guys have some available in small quantities. Can't comment on the price, but I think they are worth it.

https://www.microfasteners.com/home.php?cat=620
 
I like mine...

I purchases a flying RV7a that already had them on the plane. I have not had any issues with the flat head scratching the paint. Just watch your coffee intake...
 
Albany

I use them as well...BUT... they do not have 100 degree flat head 6 lobe screws.

Those are the ones used on most of the access panels.
 
Yup. I checked back through my records and the Torx 100 deg flat heads came from Micro Fasteners. The Torx truss head screws were from Albany.
 
yes

Micro fasteners does indeed stock the SS 100 degree FH screws.

The question is, "Are they adequate to replace the AN509 screws called for in the plans?"

The AN509 screws are listed as structural with a strength of 125,000 psi; most Stainless screws are around 70,000 to 80,000 psi.

Will they work? Probably, but you have to wonder why the engineer specified structural screws in the first place...
 
rocketman1988 said:
Micro fasteners does indeed stock the SS 100 degree FH screws.

The question is, "Are they adequate to replace the AN509 screws called for in the plans?"

The AN509 screws are listed as structural with a strength of 125,000 psi; most Stainless screws are around 70,000 to 80,000 psi.

Will they work? Probably, but you have to wonder why the engineer specified structural screws in the first place...
Click to expand...

I my case I use them for access covers as well as attaching various fairings, boot cowl, and wing/tail tips. Pretty common uses on RV type aircraft.
 
point

My point was that for the access panels, for example, the plans call for an AN509 structural screw...the stainless screws only have about 60% of the AN509 screw.

There was a reason the engineer specified an AN509 structural screw...he could have specified a non structural screw just as easily...
 
rocketman1988 said:
There was a reason the engineer specified an AN509 structural screw...he could have specified a non structural screw just as easily...
Click to expand...

Maybe the design decision was not about structural strength of the screw.
Van's catalog only shows countersunk structural screws. The only exception is #6 screws and stainless screws. Maybe, the design decision was to eliminate the potential error of using a non structural c/s screw where structural screws were needed and to reduce number of items that they need to inventory. Van's doesn't specify soft rivets even though they may be preferred when riveting nutplates to fiberglass parts.
 
rocketman1988 said:
It would be annoying when the straight slot driver slides out of the sky bolt and puts a chip or scratch in your beautiful paint job...
Click to expand...

I have the slotted Skybolts on my 7. The screwdriver can not slide out of the slot as it is a closed end slot machined into the head (metal left on both ends). No easier to have the Slot screwdriver slip than when using a Phillips that is slightly worn.
 
I hate to ask this question, but I will anyway.

Should I prime the interlocking flanges? I have seen some that are not. I sort of don't want to prime them.
 
Structural

"...Maybe the design decision was not about structural strength of the screw..."

I actually made some calls today about this. Had a nice discussion but to summarize:

If the access panel has a proper doubler, the screws do not need to be structural as the doubler is carrying the loads.

If the skin has a pre formed joggle that the access panel sits in, structural screws are technically recommended as there is no doubler to carry the loads.

Structural screws have a minimum strength of 125,000 psi

Stainless screws have a minimum strength of around 75,000 to 85,000 psi

All that said, this is experimental aviation and everyone is free to choose...

This post is ONLY about passing on information...
 
rocketman1988 said:
"...Maybe the design decision was not about structural strength of the screw..."

I actually made some calls today about this. Had a nice discussion but to summarize:

If the access panel has a proper doubler, the screws do not need to be structural as the doubler is carrying the loads.

If the skin has a pre formed joggle that the access panel sits in, structural screws are technically recommended as there is no doubler to carry the loads.

Structural screws have a minimum strength of 125,000 psi

Stainless screws have a minimum strength of around 75,000 to 85,000 psi

All that said, this is experimental aviation and everyone is free to choose...

This post is ONLY about passing on information...
Click to expand...

Thanks for passing on the information. Saves me a call. At least I can now make an informed decision.
 
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