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Checking torques at CI

00Dan

Well Known Member
When checking bolt torques during a condition inspection, do you check all or just certain critical points?

On the spar for example, do you check all the little bolts along the length or just the main bolts in the center?

Do you ever pull cotter keys and check bolts that have a castle nut or only bolts that use a lock nut?
 
My thoughts..

I built my RV-4 and therefore do all my condition inspections. I'm also an AP/IA and inspect dozens of certifieds as well as RV's and experimentals. It is not standard inspection practice to "check torques" unless driven to do so by prescribed need, such as prop torque on a wood prop, spark plugs or anything removed/tampered with. If there are signs of a lose fastener indicated by wear marks, black deposits around the heads,ect., a torque verification needs to be done. Typically, permanently istalled bolts such as spar carry-throughs, ect. are torqued at install (and hopefully torque striped) and that's all they need. Read all the VANs service bulletins for your model, and some suspect areas may be already put on a "check at inspection" cycle. No need to unsafety anything that doesn't show signs of movement. Most cotter pin safety's are on items that don't get a hard torque, and doing so may create more harm than good. These are basic guidelines, and I cant begin to cover all scenarios. You may want to pair up with a seasoned inspector on your first one and learn some pointers.
 
I built my RV-4 and therefore do all my condition inspections. I'm also an AP/IA and inspect dozens of certifieds as well as RV's and experimentals. It is not standard inspection practice to "check torques" unless driven to do so by prescribed need, such as prop torque on a wood prop, spark plugs or anything removed/tampered with. If there are signs of a lose fastener indicated by wear marks, black deposits around the heads,ect., a torque verification needs to be done. Typically, permanently istalled bolts such as spar carry-throughs, ect. are torqued at install (and hopefully torque striped) and that's all they need. Read all the VANs service bulletins for your model, and some suspect areas may be already put on a "check at inspection" cycle. No need to unsafety anything that doesn't show signs of movement. Most cotter pin safety's are on items that don't get a hard torque, and doing so may create more harm than good. These are basic guidelines, and I cant begin to cover all scenarios. You may want to pair up with a seasoned inspector on your first one and learn some pointers.

Good information. I’m working with an A&P on this since I’m not the builder. I had read on here that many people check the spar bolt torques every year which prompted my question.
 
I put a wrench on many fasteners during an annual, and find many under torqued, offhand the most common being (torque seal is meaningless IMO):

Horiz/vert attach
engine mount to airframe
landing gear attach
Engine exhaust/intake bolts/nuts/clamps

I usually check a couple of the spar bolts, if I find any loose I do them all.
You can check engine mount bolts with an open end wrench without removing the cotter key.

Basically you cannot tell if a bolt is tight by looking at it.
I have found many bolts that are to long (spin/shanked) even thought they are "tight'.
 
Consider the elevator/rudder lock nuts on the rod end hinge shanks. They're found loose all the time.

Most of the tailwheel models will eventually lose bolt tension where the stinger mount weldment is bolted to the fuselage bulkheads.

The common factor to both is that there is paint in the clamped stack.
 
I put a wrench on many fasteners during an annual, and find many under torqued, offhand the most common being (torque seal is meaningless IMO):

Horiz/vert attach
engine mount to airframe
landing gear attach
Engine exhaust/intake bolts/nuts/clamps

I usually check a couple of the spar bolts, if I find any loose I do them all.
You can check engine mount bolts with an open end wrench without removing the cotter key.

Basically you cannot tell if a bolt is tight by looking at it.
I have found many bolts that are to long (spin/shanked) even thought they are "tight'.

At the risk of being pilloried for asking a dumb question, is there a master list published somewhere of what the various torque values should be by assembly?
 
At the risk of being pilloried for asking a dumb question, is there a master list published somewhere of what the various torque values should be by assembly?

It’s my understanding that most parts use the standard torque for the bolt size and loading (shear or tension).
 
Vetterman recommends checking the torque of exhaust gasket mounting nuts at each condition inspection. I do. Vetterman spec'd mine (RV-10) at 140 in-lbs.

Per page 29 of Van's "What's Your Condition?" briefing, "It is fairly common for fasteners on a thick stack-up of parts to lose preload after accumulating some flight time." So every 5 years I check the torque on engine mount-to-airframe bolts, landing gear bolts, wing attach bolts, VS and HS attach bolts.

References:
https://www.vansaircraft.com/wp-content/uploads/2019/02/Whats_Your_Condition_Inspection.pdf
Airframe torque values are in chapter 5 of the RV plans, or AC 43.13-1B.

I also check the torque on my yaw damper pivot point - found it loose once.
 
I forget exactly where I found it but Lyc exhaust nuts typically go to 170-190 range (Lyc manual says 204).
Larry agreed ages ago and I though he revised his recommendation.
 
I forget exactly where I found it but Lyc exhaust nuts typically go to 170-190 range (Lyc manual says 204).
Larry agreed ages ago and I though he revised his recommendation.

Hmmm. You are certainly right that the Lycoming Table of Limits calls out 204-228 in-lbs for 5/16 fasteners. But Vetterman's web site, as of today, says

"What is the correct torque on the exhaust flange bolts?
We recommend 140 to 180 inch pounds. Anytime the exhaust is removed the internal star washers need to be replaced. The blow proof gaskets can be used again when reinstalling the system."
 
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