Aircraft grade nuts and bolts

[alan]

Can anyone shed any light on the difference between aircraft grade nuts and bolts and regular high tensile bolts. Often replacing locktite nuts is a hassle as once removed they should be replaced with new ones. Is it OK to use good quality lock tite nuts from an engineering supplies shop. What is the tensile strength difference between cap screws from example Solo Wings and locally bought cap screws?
Anybody shed any light.

[ACE]

I believe that there is certain vital information actually stamped on the head of each bolt which tells all you need to know - provided you know how to decipher it.

Also, in the greater JHB area, who supplies Aero Grade bolts ??

Comments anyone..

[RudiGreyling]

Go Here for Bolt Head Markings and info:
http://www.zenithair.com/kit-data/ra/hardware.html

[Morph]

Also, in the greater JHB area, who supplies Aero Grade bolts ??

Comments anyone..

I would phone the pilot supply centres at Grand Central or Rand and find out who supplies bolts.

Here in Cape Town there is a supplier in the Aviation Business Centre at CT International.

[Boet]

Demon is right. We do not use HARD bolts on aeroplanes. We use TOUGH ones. IE: Bolts that bends a lot before they will break. Nothing wrong with the local supplied 8.8 grade bolts. Happy to fly with them any day. Seems to be "tough" enough!! :D :D :D

[alan]

Thanks for the informative replies. Situated away from the real world here makes learning a slow process and obtaining the right materials even slower. :D

[DarkHelmet]

Alan - if you need anything sourced I am more than willing to get it for you and ship it down...

[skybound®]

Think there are also some other distinct differences.

The threads in particular are rolled instead of cast or something like that. Try sticking a normal nut onto an aircraft bolt. It doesn't work owing to the thread difference.

Don't aircraft bolts get x-rayed too before release to ensure no weak points.

[Redeye]

The threads in particular are rolled instead of cast or something like that

Thats one of the important points another is the quality of AN bolts is subject to much strickter controls- Main Air and Aviate use A/N bolts
They are available in a huge variety of shank lengths so the corect bolt can be used without any load being on the threaded part of the bolt
I think it should be stanard use on all planes trikes included

[Sonex711]

I think it should be stanard use on all planes trikes included

I would have thought it was standard. Scary!

[Redeye]

As far as I know the only local trike that uses them is Manfred- I remember a thing with windlas flying wire atach bolts that were atached with the tangs bearing on the cut threads of normal bolts- Windlas s solution to this was to turn the bolt upside down - this is not standard practise with aircraft- Two R20.oo A/N bolts of the corect shank length
would be a far better and safer solution (R40 is cheap insurance to do the job properly)

We buy our A/N bolts from Placo at Rand- Eric is very helpful towards homebuilders and he also has the corect drills for the A/N bolts- If you need a lot of them order from the big US mail order houses like Spruce-

It makes no sense to use anything but A/N - Manfred told me once how litle the incraese was in the cost of building a trike with A/N bolts
I cant under why some manufactures penny pinch on this critical item

[Morph]

I know the Challenger only uses AN type bolts and they are very critical as to the length. I can't believe that there are trikes flying using anything else. Scary

[Axl]

To the best of my knowledge:
AN bolts do get x-rayed (I think it's a requirement for certification), and each one comes with a serial number printed on the packet and one can supposedly trace it to the machine where it came from. AN bolts are also supplied with Imperial threads on them (i.e. inches), so that is why a standard Nylock Nut which you can buy from any bolt and nut supplier in SA, and which is threaded using Metric standard (i.e. millimeters), doesn't fit.
Locally manufactured Grade 8.8 bolts (it's got numbers 8.8 printed on the head) are an equivalent of the AN bolt standard, except each one is not x-rayed and doesn't come with it's own certificate and can only be traced by batch. They are supposed to comply to an ISO standard.
Most local manufacturers use Grade 8.8 bolts as they are easy to obtain and don't cost "an arm and a leg" and possibly a kidney... :D

On the point of shearing - any bolt of incorrect shank length may shear if it is used in the area where shear load is applied. AN or Grade 8.8 makes no difference. It is very important to make sure that only the shank (non-threaded) part of the bolt is working.

[Redeye]

Locally manufactured Grade 8.8 bolts (it's got numbers 8.8 printed on the head) are an equivalent of the AN bolt standard

I dont agree - local 8.8 s have cut threads - cut threads can set up stresses in the metal that rolled theads dont do- Some of the east block MIL spec metric bolts are the same quality but not our local bolts- AN bolts stand for US army/navy MIL spec- they dont cost all that much more when you look at the oveall costs of your plane- For me a bit more expensive proven safe fixing should be the only way to go.
I went to a talk by a EAA expert on fixings in aicraft-- scary stuff- I still have the written notes from the lecture if anyone wants a copy PM me

[RudiGreyling]

Go Here for Bolt Head Markings and info:
http://www.zenithair.com/kit-data/ra/hardware.html

To quote from the link I posted:

To begin our discussion, it is absolutely imperative that you use nothing but aircraft grade hardware. Commercial grade hardware found in hardware or automotive stores is legal to use on an experimental airplane but should not be considered for even a moment. Why? Let's look at bolts as an example. Common steel bolts purchased from a hardware store are made of low carbon steel that has a low tensile strength usually in the neighborhood of 50,000 to 60,000 psi. They also bend easily and have little corrosion protection. In contrast, aircraft bolts are made from corrosion resistant steel and are heat treated to a strength in excess of 125,000 psi. The same comparison applies to most hardware items. So, use only aircraft quality hardware on your airplane. Save the other hardware for your tractor.

In addition not all AN bolts get X-rayed only some and the are marked on the head.

READ the information provided in the link...

Regards
Rudi