Hi-lok Holes 1

[Ecpilse]

Is there a standard out there that gives the hole deminsions for specific hi-loks? I am retired Air Force and now working for a company that provides major structural overhaul for military aircraft using the military technical guidlines. Is there something that the general or comercial aviation uses for hole preperation on the installation of hi-loks?

Thanks,
Jimmy

 

[inertia4u]

Try any commercial Structural Repair Manual (SRM). From what I remember, Hi-Loks need to be installed in transition fit holes. I believe section 51 of the SRM's tells you the size for each fastener. Good Luck!


-----
Nert

 

[PhilLee]

Jimmy,
Here's a link to th Hi-Shear corporation website where they have published Hilok allowables as well as an installation guide. There, they recommend not exceeding an interference fit of greater than 0.0015. As Nert indicated though, the SRM is always the best reference.
Phil

http://www.hi-shear.com/fastener_hl_stds.htm#CollarSelection

http://www.hi-shear.com/brochures/Hilok_Hitigue_Installation.PDF

 

[koopas]

Take a look at SRM Chapter 51-40-05.

 

[AeroE]

Use class 2 holes for basic installation of hi-lok fasteners. Use class 1 holes where specified for fatigue critical installations - pay attention to the repair manual in this case. Ease the hole fit to one between class 2 and 3 for installation in composites. "Hi-tigue" hi-loks have a bull nose feature that can lightly cold work a hole of the correct diameter - the Navy permits a fatigue improvement factor, the USAF does not for this type installation.

Remember, hi-loks can also be used just like conventional bolts, in comparable holes, also. Occasionally I have used them in joints that required a high strength fastener where I didn't have access to install the head and nut on opposite sides of the joint.

 

[darrenm]

I have hole sizes for hilok bolts from the Boeing Liaison Handbook (commercial), typical installation in Aluminium is in a transition fit hole except in fatigue critical areas such as at lower wing joints. (in 3 years of liaison engineering at Boeing I only specified a non transition fit once). Installation in steel and Titanium requires a "close ream" hole that has a larger diameter but a smaller tolerance than the aluminium hole (or Aluminum for US citizens)

If you would like I could scan and email you the section.

 

[koopas]

Aren't Hi-Loks installed in interference fit holes instead of transition fit holes?

AeroE: how did you install the Hi-Lok if you didn't have access to the other side of the joint?

Alex

 

[Sparweb]

koopas,

Please take a moment and read the Hi-Lok catalog.


STF

 

[koopas]

Happy new year Sparweb,

Ummm...I am a bit confused. I am reading the 717 SRM and it states:

"Hi-Lok pins installed in aluminum structure must be installed into interference-fit holes unless
otherwise specified on the Engineering drawing."

When consulting the Hi-Lok hole size table, the majority of the holes are inteference fit. What's happening?

Alex

 

[Sparweb]

Interference fit: no argument from me.

Access to one side: The whole point of the Hi-Lok is that you only need to wrench it from one side to install it.

STF

 

[Bidonro]

Jimmy, the pin to hole clearance fit in airccraft structures is typically 0.0005 to 0.0035 diametrically.
Bob B