AN509-8 R8 (MS24694) alternative?

[BruceMe]

We all know, love and swear at these good old -8 screws. Does anyone know of any better alternative? My RV-4 came with these crazy tri-wing screws. I used them and I kinda liked them, but they stripped just as easily (maybe easier). Has anyone tried Torx, hex or square head alternatives? What do you think? Are they structural (graded/certified) or non-structural (box store)?

Thanks,

-Bruce

[rv8ch]

These guys have torx aka 6 lobe screws: http://www.microfasteners.com/

They have stainless steel, but I would be happy to see them offer a cadmium plated option. http://www.finishing.com/136/09.shtml

[scsmith]

The AN509 screws are structural strength screws, 125,000 -- 145,000 psi material. They are used in specific locations where that strength is important (like the gas tank attachment screws, which carry a lot of shear).

The Microfastener 6-lobe screws are great for places where structural strength is not important, like holding wing root fairings on, removable floor panels, inspection panels. Typically these locations would use AN507. But I would not recommend deviating from the plans in a place where AN509 screws are called for.

[ChiefPilot]

Originally Posted by rv8ch

These guys have torx aka 6 lobe screws: http://www.microfasteners.com/

They have stainless steel, but I would be happy to see them offer a cadmium plated option. http://www.finishing.com/136/09.shtml

These were recommended to me by a local builder but I found they galled, stripped, and even broke at a far greater rate than the AN509 screws. I ended up throwing them out and replacing them with AN hardware.

[rv8ch]

Originally Posted by ChiefPilot

These were recommended to me by a local builder but I found they galled, stripped, and even broke at a far greater rate than the AN509 screws. I ended up throwing them out and replacing them with AN hardware.

I have not (yet) had any of those problems, and I only plan to use them in non-structural applications. It would be great to get some real AN/MS hardware with the torx head - I find torx much less likely to strip than phillips or even allen heads. I also would prefer if they were cad plated.

[alpinelakespilot2000]

Originally Posted by BruceMe

We all know, love and swear at these good old -8 screws. Does anyone know of any better alternative? My RV-4 came with these crazy tri-wing screws. I used them and I kinda liked them, but they stripped just as easily (maybe easier). Has anyone tried Torx, hex or square head alternatives? What do you think? Are they structural (graded/certified) or non-structural (box store)?

Thanks,

-Bruce

Try GAHCo--They are a aviation hardware supplier and, I think, advertiser here. They've in the past offered AN/structural strength torx versions. They may even have some in stock. Usually they just need to know there is a demand. In any case, they are a great company to work with.

[JohnInReno]

These work if you don't need counter sink screws:

NAS1096 HEX HEAD SCREWS

http://www.aircraftspruce.com/catalo...ickkey=3011741

[David Paule]

As far as I could determine, the AN509 is the same as the MS24694 which superseded it. These are 125 ksi flat head screws.

You might try the NAS1202 screws for the #8 size, and NAS1203 for the #10 size. I couldn't find a spec on them but Aircraft Spruce carries them and advertises them as 160 ksi. That will make them stronger and the heads less likely to get messed up.

Dave