would that be that picture of the "special" fasteners, like the figure-8 shank (for close drilled holes), or the "stepped" shank (for mis-aligned holes) ??
No, I was serious, we just did a repair on a part we supply and had a lot of trouble stopping the fastener from rotating while applying enough torque to snap off the nut on the collar. I've worked a lot with aluminum and titanium collars and have never actually broken an allen key in a pin before. The theory says around 25 inch pounds for an alum. collar and 90 inch pounds for stainless on a 1'4" fastener but the practical instalation was painful.
I've broken plenty of allen keys inside of pins before, but typically whilst removing them. It sounds like you may have the wrong pairing of collar and pin.
Yes, I checked Hi-Shear's web site and it doesn't seem to be a "normal" combo. It's apparently standard on the 787 though, according to our engineer at Boeing the assembly folk down there are having fun as well. We did a repair with some 3/16" fasteners, kept the hole to minimum and didn't have too many problems. 1/4" fasteners with a transition fit was where we first had the issue.
On the 787 static test plane We had to install some 3/8" titanium NX hi-loks with BH steel collars and the torque required to break these off was unreal. If I had 3 collars to break off I went to the tool crib and got 3 brand new red T-handled allen keys. We used a jiffy Hi-torque Hi-lok runner, and I held the T-handle with 2 hands. After the first one I had to go get leather gloves because the pain of the Rubber grip trying to twist in my hand was unbearable. Right before the collar broke off the runner sounds like it about to die,starts making these weird noises. The last one we broke off was near some structure and with 2 hands I couldn't stop my hand from twisting into the structure ripping a hole in my glove and drawing blood. I knew better than to come off the hi-lok or it would strip it for sure. I can't imagine breaking these off with a ratchet or wrench without the risk of when it breaks the tool would cause a tool make or hurt the used. I quit working on the 787 because I was only making a little over 13.00 an hour working in final assembly in Everett.
Sometimes we had problems in the factory when using hilocks.
We used to cut a little bit the collar when applying a very high torque and it didn´t break.
I think that happens because of bad quality controls of the manufacturer of the rivets.
First we applied the torque, and when it didn´t break we cut the collar.
Maybe working with aluminium is not a problem, but as you may know when working with composites you can break the matrix because of a very high pressure load. I´m talking about defective rivets, not about forgetting the maintenance manual and applying a more comfortable torque than required.
saksmito - you say you were working in the factory - what does a maintenance manual have to do with factory part production? And where in the applicable fastener installation specification does it allow cutting of hilok collars?
We did manufacturing and repairment. The comment about the maintenance manual was just a way of talking.
About the second question no, not any fastener manual allow to cut hilocks. Anyway I was just kidding. We didn´t cut any hilock.
Anyway the problem is not a joke. You can break the matrix when applying a higher load than the specification of the rivet.
Sorry. I´m a very bad joker and don´t make any fun.
When he says that he "cut" the hi-loks does he mean that he ran a tap through them??? Other than removing the coating on the thread of the collar wouldn't that also cut into the locking indents, (or would it just displace them??) collar would still torque off at the mechanical breakage value but would it stay on in service?? Folk wonder why I don't like flying!
Makes you wonder about the structural integrity of what we fly on these days doesn't it?. Just read a web survey about the wages being paid and the experience level of people working on the 787 at various employers, things have sure changed in the industry.
The only collars that you apply a torque to don't break off. I think I read that article about the 787 and I can tell you from first hand experience things at Boeing are no different. Low wages,no experience,low morale. They say only 4 percent of Boeing workers make under 20 an hour well 90 percent of the 787 workers make less than $15.
I believe when he is talking about "cutting the collar" he means cutting the collar at the collar wrenching device thus making it look like the collar was properly installed, but really it never reached the design torque to snap off. Either that, or they are scoring the collar at the wrenching head causing the collar to torque and snap at an easier torque point.
Either way, that would overcome the design flaw in the fastener (ha,ha)(what....no sense of humor?)
I hope someone from Boeing reads these threads, but then again, would they really care?
Yep, we've had supplier QC issues. We tried a number of things initially, additional ceytl lubrication etc etc. I know we broke at least 3 hi-shear tools in different fixtures. In all instances they broke at the HAZ of the welded neck on the tool which is not a typical failure mode.
We changed to suitable alternate collars with aboslutely no supplier fastener support from the fastener manufacturer or the tool manufacturers....
