Smoking rivets - Cessna strut

[slacktide]

And I'll stick by those claims until you prove me wrong with a valid reference from Cessna.
Put up or shut up.

Excerpt rom the FAA approved Cessna SRM. These are the only fasteners you can legally substitue for the rivets listed in the parts catalog. No jo-bolts are listed. The listed fasteners are pull-type Cherrymax style rivets. Tom, do you even know the engineering reason WHY Cessna will not permit a jo-bolt to substitute for a rivet? Hint, it has nothing to do with the static strength of the fastener.

 

[slacktide]

Same manual
page 51-40-00 page 1 para C

1. Hi-Shear Rivets.

(1) When Hi-Shear rivets are not available, replacement of sizes 3/16 inch or greater rivets shall be

made with bolts of equal or greater strength than the rivet being replaced, and with self-locking nuts of the same diameter. It is permissible to replace Hi-Shear rivets with Hi-Lok bolts of the same material, diameter and grip length.

You should actually read.

A Hi-Shear rivet is not a driven rivet, which is the fastener that we have been discussing on this thread. This is a Hi-Shear rivet.

It works in conjunction with a collar that is swaged on with a hydraulically actuated tool. It is permissible to subsitute a High-Shear with a Hi-Lok, which has a threaded collar that shears off at a pre-determined torque. This is a Hi-Lok:

Neither a Hi-Shear not a Hi-Lok is a jo-bolt. They are different things, and you may not subsitute one for the other without engineering coverage. There is no Cessna pemitted substitution for a jo-bolt to replace either a driven rivet or a Hi-shear. This is a jo-bolt:

 

[Paulie]

In over 40 years at major airlines, military contracts and general aviation I have never seen a jo bolt tool. Why buy it when a hi lok can be used and requires no special tooling.
Typically fasteners such as jo bolts and huck bolts are used in production where it speeds up production.
I had a Mooney E that because of the idiot that owned it before me I had to replace the spar huck bolts, called Mooney engineering and they ok’d the use of hi loks in place of their factory installed huck bolts.
Forget the tool, I’ve never seen a jo bolt that wasn’t already installed.

 

[Tom-D]

Forget the tool, I’ve never seen a jo bolt that wasn’t already installed.

Unless you work in manufacturing you probably never will.

To the OP.... Go get a different strut. Save all the problems from the guys who will have a fit at your next annual.
The thread is proof they are out there.

 

[Tom-D]

In over 40 years at major airlines, military contracts and general aviation I have never seen a jo bolt tool.

. Unfortunately I have, I went thru the episode of the EA6B's cracking main wing beam caused by loose fasteners.

 

[JAWS]

To the OP.... Go get a different strut. Save all the problems from the guys who will have a fit at your next annual.
The thread is proof they are out there.

Some maintainers believe in maintaining standards. Some believe in "TLAR". There is a time and a place for both. Primary structure isn't the place for guessing.

 

[JAWS]

. Unfortunately I have, I went thru the episode of the EA6B's cracking main wing beam caused by loose fasteners.

I bet those military repairs had some time spent by engineers evaluating the structure and ensuring the proposed repair would maintain standards. Maybe even a simple phone call to the manufacturer?

 

[Dan Thomas]

The strut has a square aluminum bar (lug) on the bottom end and a cast or forged aluminum fork lug with a square cross section on the upper end. If one rivet is smoking, I would be looking for that bar to be loose in there, at least a little bit. SImply replacing a rivet isn't smart; it's loose for a reason, and that strut may be cracked at that point, or the airplane was overstressed and the lug has been pulled a bit, maybe partially shearing some or all of the rivets. Or the lug itself is cracked. Or there's corrosion. You never know until you get a really good look and do some NDT.

Glider tugs fly in a lot of thermal and upslope turbulence, hammering away at the structure.

 

[Tom-D]

Some maintainers believe in maintaining standards. Some believe in "TLAR". There is a time and a place for both. Primary structure isn't the place for guessing.

IF all A&P-IAs were on the same page with repairs, we wouldn't have the problems we do with repairs at annuals by other A&P-IAs

 

[JAWS]

IF all A&P-IAs were on the same page with repairs, we wouldn't have the problems we do with repairs at annuals by other A&P-IAs

Very true. We have inherited the unforeseen consequences from the days of annuals costing $200 and a case of beer!

 

[JAWS]

The strut has a square aluminum bar (lug) on the bottom end and a cast or forged aluminum fork lug with a square cross section on the upper end. If one rivet is smoking, I would be looking for that bar to be loose in there, at least a little bit. SImply replacing a rivet isn't smart; it's loose for a reason, and that strut may be cracked at that point, or the airplane was overstressed and the lug has been pulled a bit, maybe partially shearing some or all of the rivets. Or the lug itself is cracked. Or there's corrosion. You never know until you get a really good look and do some NDT.

Glider tugs fly in a lot of thermal and upslope turbulence, hammering away at the structure.

Yep!

 

[Tom-D]

Yep!

What's the best fix, and probably the cheapest?

Different strut. like Tommy said to start.

 

[kontiki]

Maybe a photo of the spot would be helpful, based on the description and my recollection of a Cessna:

See anything here to cause a major repair?

(xi) Wing or tail surface brace struts.

 

[Tom-D]

Maybe a photo of the spot would be helpful, based on the description and my recollection of a Cessna:

See anything here to cause a major repair?

(xi) Wing or tail surface brace struts.

Another reason for a different strut.. hard to believe changing a rivet could be considered a major repair.