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Skybolt fastener adjustment

PeteP

Well Known Member
Starting to adjust my skybolts to the final depth setting. Looks like if you tighten them too snug it will be very difficult to have enought depth to get then to release when removing. Any good tips or ideas on the proper snugness before removing the locking pins?
 
They tell you how much 1 turn will adjust the fastener. They're something like 40 threads per inch. Put the cowl on and note beside each fastener approx how many turns up or down they need to go... Remove cowl and adjust. Re install cowl and see if ya got it right. Repeat till you're tired or happy...
 
I did Mil-Spec but it should be pretty similar. Put the cowl on, tighten the fasteners as if they were screws, and spend some time making sure all the fastener heads are nearly flush with the grommets (better slightly deep to slightly proud). You will find that tightening/loosening one will change the neighbors, so take your time. Beat on the cowl a bit to be sure it is settled into place. When you are happy with the fasteners, remove them by pushing in fully to disengage (being lazy here will undo your adjustments). Start at the corners, which tend to be tightest, and work toward the edges. Now you can pull the pins, reinstall the cowl, and check again; most of your fasteners should be right on. I checked again after a few flights to find a few high fasteners that I re-adjusted. I also found a couple of low ones, spotted because they broke one of the cam pins during operation - a good reason to have a few spares handy. Re-adjustment is not hard and usually takes less than a turn.
 
Mine are giving me fits as well. If I go too tight, the cowl forms a depression by the skybolt. If I am too loose, the screw is not sucked down into its fitting. I am considering adding some fiberglass to the underside of the cowling by the bolts to stiffen it up a bit. Comments?
 
Adjusting Skybolt Fastenrs

The Skybolt Diamondhead Fasteners used in Vans RV kits utilize an adjustable receptacle that we designed and patented in the early 1990s. The adjustment thread is 1/2-32 or 32 threads per inch which works out to be .030 adjustment per 360 degree turn. There are two locking grooves that allow adjustment increments of .015.

Before making the initial adjustment setting, check that the receptacle inserts are near the face of the receptacle. If they are too deep, you will not be able to engage the studs. Place the cowling in position and engage all fasteners. Screw the fasteners in as if they were machine screws until the heads are flush with the grommets. Use a quick push turn motion to unlock the fasteners without disturbing the receptacle inserts. With the cowling removed, pull all anti-lock pins. With a flat blade screwdriver, turn each insert clockwise until the receptacle locking band engages into the insert locking groove.

Note: It is possible to screw the studs all the way into the base of the grommet (head about .030 below the surface). If you had access to the anti-lock pin and removed it, it may be impossible to unlock the fastener. Without breaking the fastener, you must unlock the receptacle and return the setting such that the fastener head is flush with the grommet face. If you ever installed a Dzus fastener, our receptacle design can be described as an up-side-down Dzus fastener. The Dzus stud geometry is very similar to our receptacle insert thus the same locking dynamics.

It helps to look closely at the locking slot in the receptacle insert and note how it works. As the fastener is turned, it is drawn inward to an apex in the locking slot, then rebounds .020 to .030 into a locking saddle. So the fastener must have approximately .030 compression remaining when locked for the pin to retrace the motion over the apex when unlocking.

Re-install cowling and attempt to lock all fasteners. If the locking action requires more than about 10 inch-lbs (notable force), do not attempt to force the fastener; the adjustment at that location is set too deep. The Skybolt Diamondhead studs are very hard and you can over stress the crosspin with no galling like other brands. We have strengthened the crosspin to perform at levels beyond steel fasteners, but severe torsion will exceed the design load of the pin. Most initial adjustments should be right on the money.

For any locations where the heads are not flush or studs will not lock, use a small piece of masking tape and place it on the lower cowl or the airframe adjacent to the firewall. Write a -1, +1, -1.5.....to indicate how many half turns you estimate to make the heads flush with the grommets. If it appears the head is .015 high, mark the tape with -1 such that with the cowling removed, you know to adjust that location 1/2 turn or .015 in. If the stud will not lock, start with +1 or 1 full turn at that l location.

You can set and lock a complete cowling in the time it takes to read this information.

Skybolt is running a 20% promotion on complete Vans RV Cowling Kits from now through April 26, 2015 (Sun N Fun Special). If you have any questions, please call us at 1-800-223-1963. All Skybolt kits have our latest revisions in hardened Diamondhead studs, high shear grommets, enhanced receptacles, including our patented interlocking mounting flanges.
 
I do have problems to adjust the depth of the fasteners. The skybolt fastener kit ordered in 2010 was RV67910J-C1P (with receptacle SK245A162A).

I can't see any locking spring or something on the outside of the receptacle, instead there seems to be a small pin inside the receptacle that prevents it from turning. Does anybody has an idea how to unlock the device?
 
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Does anybody has an idea how to unlock the device?

If you look at the locking barrel, you will notice a small opening on the side (a black locking spring tab will be at that location too). Inserting a dental pick into this hole will raise the locking spring tab which will allow you to turn the Skybolt to the appropriate depth (Mine are flush with the cowl.) When you remove the pick from the hole, rotate the Skybolt forward or aft until the spring locking tab engages and locks the barrel....

I know this is probably difficult to picture. I would recommend a Youtube search which will likely prove more helpful. I was initially rather confused until I installed and re-adjusted the first one. After that it was easy peasy lemon squeezy! :)
 
Fred: thank you for your reply but my fasteners are different. There's no locking spring on the side of the barrel. There's just a pin in the barrel that i can not move. I wrote three emails to skybolt ( first three weeks ago) but no response yet. I wonder if they are still in business.
 
Can you email me a photo of the back of the receptacle? Maybe I can annotate the picture with the location of the locking tab. Also, if they are similar to mine, I can make and send you a short video of how to unlock them....

(email is preferable. it is listed in my signature.)
 
This is from the installation manual that I used.
 

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Hi Fred,

here are the pictures... there is no spring or latch or something on the outside of the barrel. instead there's a small pin inside the barrel the seems to lock the device.
 

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Yup! That does NOT look like mine.... I would have to direct you to the company's documentation if you can locate it.

I'm sorry.
 
Fred: thank you for your reply but my fasteners are different. There's no locking spring on the side of the barrel. There's just a pin in the barrel that i can not move. I wrote three emails to skybolt ( first three weeks ago) but no response yet. I wonder if they are still in business.

Perhaps you have the ones that use a special tool that is inserted into the fastener receptacle (I have those...it works very easily with the tool from SkyBolt).
 
Hi Fred,

here are the pictures... there is no spring or latch or something on the outside of the barrel. instead there's a small pin inside the barrel the seems to lock the device.

Those appear to be the type that do not have a locking band or pin in the back (the pin you see is something else, you don't do anything with that), but rather the tool is inserted into the slot and firmly pushed to disengage the internal lock, then the insert is turned in half-turn increments. You can feel the detents when turning it. It locks into place when the tool is removed.

Engage the tool into panel (through grommet) and engage into receptacle with slight pressure. This unlocks the insert and allows the tool to turn the insert until the adjuster sleeve faces with the grommet.

https://skybolt.com/wp-content/uploads/2017/08/SK-SP5-Tool-Fasteners.pdf
 
Hi Fred,

here are the pictures... there is no spring or latch or something on the outside of the barrel. instead there's a small pin inside the barrel the seems to lock the device.


So what you have there is

4000 Series Adjustable Receptacle - Non Floating - 6061/7075 Alum 1.0 Rivet Spacing - 1/8 - TSO-C148

You need the special tool from SkyBolt, but I don't see it listed in their catalog.
 
You need this tool. Problem is, I couldn't find it on the SkyBolt website, nor in their on-line catalog. I'd give them a call and see what's up.

The tool is inserted into the slit, firmly pushed, and then you can rotate the receptacle by half-turns (you can feel the detents at each half-turn).

It also contains the parts to install the C-rings on the back side of the grommets...those are kept under the rubber end cap.
 

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