Use of 1100-F "A" Aluminum Rivets

[BVF]

I have a non-structural application on a 747-400 aircraft where manufacturing has asked us to use 1100-F "A" rivets in place of the 2117-T3 "AD" rivets currently on our drawing.

My Boeing Liaison Engineering handbook from my days at Boeing says (on page 60.2.2) "Avoid using 5056 or 1100F rivets in 2000 series or 7000 aluminum. If used, they should be installed with sealant BMS 5-95. Use 2117 fasteners if possible..."

The bracket we are attaching to is 2024-T3. According to the note, I should avoid 1100F. 1100 alloy is a minimum 99% pure aluminum. In what way is it incompatible with 2000 or 7000 aluminums? Is this a corrosion issue? I understand "A" rivets are relatively weak at 9.5 ksi shear, but that is not an issue for this application. We're attaching a plastic air conditioning duct spacer to a 2024 bracket. I would prefer not to have to use the sealant here, and I don't understand why the sealant would be required.

Does anyone know the source of the Boeing note?

Brent

 

[WKTaylor]

BVF..

That table [note] does NOT include 1100 ["A"] rivets: it is for 5056 ["B"] rivets only. And, Yes it is a "dissimilarity" issue... not to mention a very poor strength match.

Note: We have a real problem on the acft I work: 2024 &/or 7075 are ofted fastened to magnesium parts [IE: very old acft design]. Our current practice is to install mag and alum parts wet with sealant in the faying surfaces... and "B" rivets "wet" with primer to protect the magnesium [or better-yet... remove the mag and replace with aluminum and install AD or D rivets].

NOTE: As for using "A" rivets in this application... unless the shop's reason is really compelling... such as attaching a light weight plastic part to an aluminum bracket with virtually NO load... then "follow the published data".

Regards, Wil Taylor

 

[Kwan]

Brent,

I would instl the rivet with sealant to prevent moisture from getting into the joint. This would be to protect the 7075.

Another thought is that a harder rivet would decrease the kt for the 7075. Also I have some data for the best rivet match for 7075 (corrosion). Can't remember which rivet right now. I'll look it up when I get back to the office. Or ask Marshall. I think I gave him some info on this.

Ted

 

[BVF]

Thanks, guys.

Wil:
Not to be pedantic, but the note clearly says not to use 1100F rivets in 2000 or 7000 series aluminum. Should I just interpret this as a mistake? I can think of no reason to prevent the use of 1100 in aluminum. I agree with you 100% on the 5056. Strength is not the issue for my application. I appreciate your experience with the magnesium parts.

Ted:
Normally, I would choose AD or D rivets, or even KE, depending on material thickness and load. I would appreciate any info you have on appropriately matching fasteners to structures.

Brent

 

[Kwan]

Brent,

I can get you this info tomorrow. Working landing gear out of state this week.

 

[WKTaylor]

BVF...

The liaison Hdbk (Ref page 60.2.2) I have access to DOES NOT include 1100 alloy rivets in this statememt... only 5056.

Regards, Wil Taylor

 

[BVF]

Thanks, Wil. That's really interesting. I've checked the three books I can find in our office. The 1986 edition has no note at all. In 1989, the note included both 5056 and 1100F rivets, but only mentions 2000 series aluminum. My 1995 edition calls out both 5056 and 1100F, and 2000 and 7000 series.

Out of curiosity, which edition is your book?

I'm inclined to think the 1100F is just a mistake that has propagated through.

Brent

 

[Kwan]

The info that I have is to use AD type rivets for 2024 and E for 7075. This will minimize galvanic corrosion.

Now, this issue with this is that bucking a rivet against plastic will be tough. The hole fill will probably be insufficient for reducing the kt in the 7075 relative to the a normal hole fill.

I would first ask the shop if they think they can buck the E with a washer on the plastic side. Perhaps a simple test can be done without much trouble. If this is not possible then I would just use the 1100 rivet.

Hope this helps.