Challenge yourself at next annual

Rick_A · #1 05-29-2014, 08:07 PM

Sharing a hanger with Walt has made a HUGE difference in quality of maintenance I perform in my airplane. He has always preached that the only way to inspect stuff (i.e. anything that is a threaded fastener) is to Put a Wrench On It. So normally, I put on wrench on "everything".

This year, I decided to look for fasteners that may not have been included in "everything" in prior years. So starting with the empennage and working forward, I put a wrench on EVERY nut & bolt. I was surprised at the number of fasteners that I was able to snug up just a bit. Sometimes it was just 1 flat or maybe a 1/4 turn - in a few cases, it was quite a bit more.

Challenge yourself on your next inspection / annual to find some fasteners that you haven't put a wrench on in a while (or ever). I'd say if you can't find a few that need to be snugged up, you're not looking hard enough!

A couple of examples that I found in my 7A
(1) There are 4 bolts in each of the steel gussets located at the very forward most lower corners in the foot well (right at the firewall). They all needed at least 1 or more full turns to get tight.
(2) Three of four bolts on the wheel pant bracket on the Right Main wheel needed to be tightened.
(3) I was able to turn one "castellation" on 3 of the 6 engine mount bolts.

There were many others I could list but I think you get my point.

BillL · #2 05-30-2014, 06:13 AM

Thanks, Rick,

I am still working to get flying, but did you remove the cotter pins on all bolts to check torque or just the engine mount-to-fuse bolts? This is certainly something I would never have thought to do.

Thanks . . .

Walt · #3 05-30-2014, 06:34 AM

Don't want to answer for Rick but you don't need to remove the cotter pin, just put an open end wrench on it and see if you can move the nut. I have found them where you can spin the washers under the nut with your fingers on the lower mount bolts.

Rick_A · #4 05-30-2014, 06:50 AM

As Walt mentioned, I didn't remove the cotter pins at first. The 3 that were OK didn't budge when I checked them.

The 3 that were loose, went to the limit that I could turn with the pins installed. At that point, I figured I'd remove the pins to see how much more I they would turn and I'm glad I did.

Guilhermepilot · #5 05-30-2014, 07:55 AM

a loctite 232 would help for those issues?

DaleB · #6 05-30-2014, 08:08 AM

Were the fasteners in question marked with Torque Seal? If so, did it indicate movement? I'm trying to understand the mechanism by which a bolt would work itself loose unless the nut has turned. Obviously engine mounts with a rubber bushing would be aother matter, but I'd like to understand how a bolt holding two pieces of metal together would loosen, other than something turning itself loose from vibration.

BillL · #7 05-30-2014, 08:22 AM

Quote:

Originally Posted by DaleB

Were the fasteners in question marked with Torque Seal? If so, did it indicate movement? I'm trying to understand the mechanism by which a bolt would work itself loose unless the nut has turned. Obviously engine mounts with a rubber bushing would be aother matter, but I'd like to understand how a bolt holding two pieces of metal together would loosen, other than something turning itself loose from vibration.

Thanks Rick that avoids a lot of cotter pin removals, but gets the job done!!

Now to the quote - imagine taking several pieces of paper and crumpling them, laying back flat, then stacking them and comparing to the same number of flat sheets. The lack of perfect flatness can allow some relaxation of some joints. We should note here that nearly all aviation fasteners are designed for shear loads not clamping force. The engine mount to fuse bolts do load in tension but their torque is not that high ( compared to automotive etc) . It is easy to imagine some settling in with the different layers involved even if the fastener remained unstretched or loosened. Also they have powercoat (paint) in that joint too. 20-20- hindsight would apply here. While it is understandable, I would not have predicted it, and very grateful for the OP.

DaleB · #8 05-30-2014, 08:58 AM

So - if I understand correctly, any indicating lacquer was intact, things just loosened up as the result of some "settling in", etc - so I'd expect the incidence of loose fasteners to decrease in number and severity over the years.

Interesting. Some day I'll be doing annual inspections, I'll certainly keep this in mind.

Rick_A · #9 05-30-2014, 06:46 PM

Quote:

Originally Posted by DaleB

So - if I understand correctly, any indicating lacquer was intact, things just loosened up as the result of some "settling in", etc - so I'd expect the incidence of loose fasteners to decrease in number and severity over the years.

Most of the fasteners that I checked did have torque seal lacquer on them and the torque seal was intact in every case.

Torque seal helps you to keep track of which nuts & bolts you've torqued at a point in time or while building. It does not indicate that the fastener is still properly torqued after some period of use.

DaleB · #10 05-30-2014, 07:20 PM

Quote:

Originally Posted by Rick_A

Most of the fasteners that I checked did have torque seal lacquer on them and the torque seal was intact in every case.

Torque seal helps you to keep track of which nuts & bolts you've torqued at a point in time or while building. It does not indicate that the fastener is still properly torqued after some period of use.

No, of course it wouldn't... but it will tell you if the bolt or nut has turned. I was just curious as to whether you'd seen any of them that had broken loose as opposed to stretching, settling or wearing.