Wet Rivet Shear Strength 4

[YoungTurk]

When installing rivets in aircraft structure (sheet aluminum), what, if any, adjustment do you make to the joint shear capability for solid (AD) rivet installation with a sealant (wet install)?

Niu suggests a 20% reduction if no test data is available. MMPDS specifically discusses the rivet being solvent wiped. I'm inclined to think introduction of a thin layer of sealant will act as a lubricant and reduce shear capability for bearing critical joints. This is being met with skepticism from other engineers. Opinions welcome, references appreciated.

 

[rb1957]

OMG !

 

[Sparweb]

Sometimes I wish those conical fillers hadn't been invented.

For the lazy shop worker, he can leave them out, do the job faster, yet still sleep at night "cuz she'll hold".

For the engineer, it's easy to call up on a drawing, and sleep at night knowing he specified the right part.

For the inspector, he visually sees all the rivets in place, so he'll sleep at night knowing that the job is done.

Everyone is happy, even when those little things are not there. Fortunately for me, most aircraft I work on get less than 500 hours per year.


Steven Fahey, CET

 

[graemew]

G'day rb1957:
I confess that I agree with you about wanting a bit more info.about CSK fillers.
I also have called them up for use, and unlike the experience of others, mostly they have been used. Maybe because I "hover around" at times and they are afraid that I will catch them leaving them out. Who knows??
I know that Boeing have a part numer for the little things and it is possible that they have done the sort of research that you are talking about.
Are there any Boeing people out there who might care to shed some light on the subject?
Regards
graemew
"Let me bring order to your chaos"

 

[graemew]

wktayor
G'day Wil
Loctite advise that:
"The Primers concerned have copper salts (in minute quantities) to serve to accelerate the polymerisation (curing) process of the anaerobic.

Primers are used in circumstances such as:

inactive metals (eg Stainless Steel etc)
need to reduce cure time
when gap is more than 0.1mm (but less than 0.2mm)


If there is concern, acetone may be used to clean areas that may be subjected to overspray."

Copper salts in any quantity, if not washed away thoroughly will result in corrosion if the surface that they are on is exposed at all. It certainly explains the corrosion that I have seen around where the loctite primers have been used for bearing installation. I guess the message is: use primers, but wash well afterwards.
Regards
Graeme
"Let me bring order to your chaos"