Wing Spar Bolts and Engine Mount Re-Torque

[JonJay]

I am curious to hear from experience RV mechanics like Mel and Walt on the subject of re-torqueing spar bolts, both early laminated spars and current machined spars, and engine mount to firewall bolts.
What are others doing, if anything, and if so, at what intervals.

[Walt]

I check them on every condition inspection and I have found both spar and engine mount bolts (mount/airframe) under-torqued/loose on many aircraft.

[Low Pass]

Very interesting. Old spar, new spar??

[JonJay]

Thanks Walt.
Interesting that most of the condition inspection check lists I have reviewed do not include checking these.

[Walt]

Originally Posted by Low Pass

Very interesting. Old spar, new spar??

Both

Originally Posted by JonJay

Thanks Walt.
Interesting that most of the condition inspection check lists I have reviewed do not include checking these.

I check all critical bolts with a wrench to ensure they are tight, looking at them don't cut it (pretty hard to tell if a bolt is loose or sheared by looking at it).

This includes but is not limited to all: engine controls, flight contols and primary structure (especially vert/horiz attach and wing spar), fuel/oil line fittings/B nuts etc..

I also check things like sump bolts, mag bolts, exhaust hanger bolts, exhaust/intake cylinder bolts, MLG attach/fairing attach, tail wheel attach nuts/bolts.

I also don't care if "torque seal" is there they can still be loose (and have been).

You get the idea.

That's also the reason I schedule a week for condition inspections, anyone that says they can do a good inspection in 1 or 2 days.... well I better leave that one alone before I get in trouble.

[Mel]

Believe it or not; I have found loose bolts/nuts on initial airworthiness inspections that have torque seal on them.

[JonJay]

Originally Posted by Walt

I check all critical bolts with a wrench to ensure they are tight, looking at them don't cut it (pretty hard to tell if a bolt is loose or sheared by looking at it).

.

Ditto - Specific to the Mount and Spar, this is how I discovered a couple bolts needing to be tightened. I chose to re-torque all of them, which revealed that a couple where slightly under torqued, even though they passed the "wrench" test.
I assume you do not put a torque wrench to each bolt at each CI or am I mistaken? I think there are some odd 60 AN3's in a 6's spar alone.

I am not trying to get carried away here, just want to know what the "pro's" do. I only have one RV to take care of.....

[Christopher Murphy]

Originally Posted by Walt

I check them on every condition inspection and I have found both spar and engine mount bolts (mount/airframe) under-torqued/loose on many aircraft.

I am curious if these under torqued bolts were installed that way and then discovered or if they were properly torqued and found loose at a later inspection.
The spar bolts, when properly torqued using lock nuts should not be coming loose.

Chris m

[JonJay]

Originally Posted by Christopher Murphy

I am curious if these under torqued bolts were installed that way and then discovered or if they were properly torqued and found loose at a later inspection.
The spar bolts, when properly torqued using lock nuts should not be coming loose.

Chris m

Chris - mine did. They where torqued at one time, 100% positive. They where not "loose" but a few did need to be tightened. Don't ask me how a torqued bolt loses it's torque, but.....
Also, keep in mind most bolts in an RV are shear, not compression or tension. A slightly loose bolt is probably not going to do anything or be a concern in most of our applications. However.....

[Walt]

Originally Posted by JonJay

Ditto - Specific to the Mount and Spar, this is how I discovered a couple bolts needing to be tightened. I chose to re-torque all of them, which revealed that a couple where slightly under torqued, even though they passed the "wrench" test.
I assume you do not put a torque wrench to each bolt at each CI or am I mistaken? I think there are some odd 60 AN3's in a 6's spar alone.

I am not trying to get carried away here, just want to know what the "pro's" do. I only have one RV to take care of.....

I have a "calibrated" arm and use a wrench to check most things. Certain things I just get out the torque wrench (like exhaust studs) and torque them.

Originally Posted by Christopher Murphy

I am curious if these under torqued bolts were installed that way and then discovered or if they were properly torqued and found loose at a later inspection.
The spar bolts, when properly torqued using lock nuts should not be coming loose.

Chris m

Who knows but I suspect many were not torqued correctly from the start.

Originally Posted by JonJay

Also, keep in mind most bolts in an RV are shear, not compression or tension. A slightly loose bolt is probably not going to do anything or be a concern in most of our applications. However.....

This may be true, but just like the recent nose gear bolt failure, a loose bolt will allow the pieces to start moving relative to each causing wear to the bolt, bolts holes etc, things start getting loose and so on.