Jo-Bolts

[aquanaut]

Does anyone know of a good source for Jo-Bolts or a good substitution?

[GAHorn]

In what particular application…?? Wing strut fitting attaches..? (If you ream the holes you can use AN5 bolts.)

IMG_2098.png

[n2582d]

Dave is probably not looking for Jo-bolts on his wing struts ... he has a '48 C-170 with completely different style struts than the later 170 models. If you look for NAS1669 or NAS1670 (Jo-bolts) in the Numerical Index of the C-170 IPC you won't find these part numbers listed. The closest thing to these style fasteners are NAS178 Hi-Shear rivets used in the landing gear box (fig. 19-81 and 19-83). General Aircraft Hardware Co. sells Jo-bolts but Google the appropriate NAS p/n for better prices. Chapter 51 of Cessna's Structural Repair Manual addresses the acceptable substitution of fasteners but I don't find any mention of Jo-Bolts there.

[GAHorn]

Like you said, we don’t know what he wants them for and that’s why I asked…. if he wants them for a space ship he can get them at monroe also. (General Aviation Hardware is a good source for lots of stuff and they’re friendly… they donated to our GLS convention)

Monroe: https://catalog.monroeaerospace.com/key ... &SchType=2

[aquanaut]

I should have been more specific. I'm looking for blind fasteners to attach a tail wheel bracket. My 170 had 4 rivets replace with jo-bolts and I was told they would be acceptable.

[n2582d]

Dave,
If you look at Table 1, "Approved Replacement Fasteners Chart," in the Structural Repair Manual I linked above, it shows that the approved replacement fasteners for MS20470AD5 and MS20470AD6 rivets include NAS1398B5 and NAS1398B6 Cherrylock rivets. A "by the book" answer would appear to be that Jo-lock fasteners are not allowed without special approval from Cessna. If you're set on using a high strength blind fastener I think Hi-Lok fasteners would be easier to install and not require the special tools that Jo-bolts require. If Jo-bolts are already installed, I'd give Cessna's tech support a call and ask them about approval.

It's interesting to read what AC43.13-1B has to say on the subject in paragraph 4-57 (f):

Blind rivets shall not be used:
...
(2) on ... landing gear fittings, ... or other heavily-stressed locations on the aircraft;
CAUTION: For metal repairs to the airframe, the use of blind rivets must be specifically authorized by the airframe manufacturer or approved by a representative of the FAA.

I assume you are replacing the steel tailwheel bracket with the aluminum "fish mouth" style as described in SK70A52-4?