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7A elevator spar crack

Mark Burns

Well Known Member
Due to the recent loss of a VAF'er I decided to inspect my empennage very carefully.

I found a crack in the right elevator spar at the outboard attach point.
This is how it looked upon inspection. Just a black line.

P1130051.jpg


I wiped the black off the left side but you can still see the crack below.

20130921_095223.jpg


And here it is after the dye penetrant test.

20130921_130940.jpg


It's an RV7A serial number 72183 with 908 hours.

Everyone please check your elevators carefully before your next flight!

Mark
 
Interesting.

Thats a pretty signficant issue I would think. Will be interesting to see if a few of these show up, and how/why it would fracture there?

Not speculating on anything of course, but anything to do with spars gets my attention quick. Will inspect asap.

Thanks for the post.
 
A loose jam nut could be the cause of such a crack, if the jam nut is loose the nutplate and nutplate rivets are carrying the full load of the fitting.

FYI - I find loose jam nuts on elevators and rudders routinely :eek:

PS: good find, everyone should inspect this area at the earliest opportunity.
 
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Whoa!

Hey Mark:

Assuming the rod end was tight, and the elev hinge line along the H stab rt side is razor straight, as is the elev hinge line, I would suspect a vibration mode of some sort here (elev counterweight involved) - I doubt you could do that with any sort of flying you would do in that plane - well - maybe 10 tail slides per day since the first flight? You're not doing that, are you?

I suspect a hinge line SNAFU, with the area of least strength (outboard hinge/smallest spar cross section)) giving up 1st. Get your dental floss and string-line bushings back out!

Could be that rivet was not driven correctly - the markings show it is a hard rivet...so that's not likely to be it.

What engine/prop combo are you running? Does it run smoothly in cruise? Did you do an engine run with the wings off way back when?? I'm digging pretty deep with that last one...

Carry on!
Mark
 
Spar Crack

Mark: Good Job for paying attention and being proactive. No way to tell how long your crack has been there but looks like a few hours. This is a good illustration of how the parts of our "airworthiness system" work together. The airplane structure is designed to be tolerant of some level of damage or defect like this spar crack for a peroid of time until the inspection process comes around to catch it. Please keep us posted on what you find and how you resolve it.



Don Broussard

RV-9 Rebuild in Progress
 
Crack

My Cessna 120 had an AD to look for such a crack , along with the Rudder on an A36 Beech Bonanza , and the horizontal on a Rockwell 112 . I do believe the fix was either doublers or spar replacement .
As inexpensive as Vans parts go , I might opt to build a new one . A complete tail kit cost about the same as the cost to inspect the A36 or the Rockwell .
After the latest inflight breakup and another post about the length of rudder rod bearings we all need to take a realy good look at the tail components .
Remember tail kits are place that most every one learns on , most with NO construction experiance .

The latest 7 to come apart looks a lot like [ed. Wait for the investigators please. dr]. There are some other reports of RV7 flutter if you search the web.

Tom
 
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Thanks

Mark, thanks for the post. I checked a friends RV-7 and found all 4 jam nuts loose on the elevator hinge rod-ends. No cracks though.
 
Mark - thanks for this thread.

On you're prompt, I just looked closer than usual at the lock nuts for both the rudder and elevator on my RV-8.

One of three on the rudder needed a wrench. One in four on the elevator needed a wrench.
 
can we publish a good inspection procedure?

As a non-builder, I want to do the right thing here.....
I went flying today, but my pre-flight included close scrutiny of the rod end/jam nut , spar rivets etc.
having just completed my annual, the first thing I noted was that applying even a tiny shot of LPS-4 lube here has now caused a lot of dust and grime to coat the components. I had to wipe each one to get a good look with a bright light.

'putting a wrench' on the jam nut ?
do I need to hold the rod end with another wrench, so that I am not torquing on the hinge? or is this inconsequential. ( not sure how I'd fit 2 wrenches in there either).
Will paint potentially hide the crack?
 
As a non-builder, I want to do the right thing here.....
I went flying today, but my pre-flight included close scrutiny of the rod end/jam nut , spar rivets etc.
having just completed my annual, the first thing I noted was that applying even a tiny shot of LPS-4 lube here has now caused a lot of dust and grime to coat the components. I had to wipe each one to get a good look with a bright light.

'putting a wrench' on the jam nut ?
do I need to hold the rod end with another wrench, so that I am not torquing on the hinge? or is this inconsequential. ( not sure how I'd fit 2 wrenches in there either).
Will paint potentially hide the crack?

I always visually check the hinge areas preflight but now I'll look a bit closer.

I put a wrench on all the rod ends in the tail today and they were fine. "Put a wrench on it" to me means just moderate pressure on the wrench with my finger tips. If the jam nuts are loose you'll feel it. If they are fine, there is no need for a backup wrench. There is no need to crank on these nuts during a check.

I have torque stripe on all my critical fasteners. That way you'll see at a glance if something has moved.

Of course, ymmv.
 
Answer a few questions

To answer a few questions:

No, I've never done any tail slides :)
I never ran the engine with the wings off.
Jam nuts were not loose.
The engine is a 0-360-A1D
Propeller is the 85 pitch Sensenich.
This combination is pretty smooth. Prop was balanced before first flight.

The paint did not hide the crack.
It may have actually helped see the crack.

One thing that I think may have caused it is wind on the ground.
I was parked at Oshkosh in 2012 just about 75 yards west of the Biplane that flipped over. I just tie my elevators back with my seatbelt. I'm sure there was quite a force on my elevators during this storm.

I plan to replace the elevator spar. If it weren't for those two -4 rivets on the counterbalance rib it would be a piece of cake. Bucking these two rivets means removing the tip that is all glassed up pretty:(

I'm going to research using a couple of Cherry Max rivets instead.

Mark
 
One thing that I think may have caused it is wind on the ground.
I was parked at Oshkosh in 2012 just about 75 yards west of the Biplane that flipped over. I just tie my elevators back with my seatbelt. I'm sure there was quite a force on my elevators during this storm.

Maybe this is appropriate for a separate thread but I have to wonder if my current control surface methods are adequate. I use a PVC device that is placed between the rudder pedals and a point by the spar in my 6A.

The seat belt is used to "secure" the ailerons and elevators.

I have avoided external systems in the past but I wonder if the devices that people place between the outside of the aileron and the wingtip might be better for the ailerons.
 
Good point Ron. Tightening those jam numbers and keeping the rod end aligned is a bear. I'll be checking my closely on my next preflight and I have an annual coming up so I'll be getting out the mirrors and magnifying glasses.
 
We here traveling this weekend and one of the things I plan on doing tomorrow evening is to remove the empennage faring and inspect (Put a wrench) on all the bolts back there and look closely (using a magnifying glass) at the VS attach brace.

While I'm at it, I will also look at the HS spar, as described in this thread.

RV-9(A) pilots / owners, don't think that because our planes are not aerobatic that this couldn't happen to us. Please take a few minutes to inspect your planes and report back any findings.
 
One thing that I think may have caused it is wind on the ground.
I was parked at Oshkosh in 2012 just about 75 yards west of the Biplane that flipped over. I just tie my elevators back with my seatbelt. I'm sure there was quite a force on my elevators during this storm.

I plan to replace the elevator spar. If it weren't for those two -4 rivets on the counterbalance rib it would be a piece of cake. Bucking these two rivets means removing the tip that is all glassed up pretty:(

I'm going to research using a couple of Cherry Max rivets instead.

Mark

Mark,
A crack like yours doesn't typically occur from a single load event. It is classic of what would be caused by some type of load reversal / flexing across that point.
One thing I would be looking for if I were inspecting the airplane, would be hinge axis alignment. I.E., if when the elevator is removed, is it easy to remove the bolt that attaches the rod end to the Horizontal stab. If not, it is an indication that the hinge points may be misaligned.
If they are, the web of the spar would be forced to flex every time the elevator moved on its hinge axis (and we know that it is probably the most active control surface on an airplane). If misalignment is found, it could be caused by mis-adjusted rod ends, misaligned horizontal stab brackets, etc. (or a combination). A check can be done with a piece of fine thread pulled tight through all three hing points for each side on the stab and elevator. It will show whether thy are all aligned.

As far as replacing the spar goes, if the proper Cherry Max rivet was used, it would be a totally acceptable way of doing the repair.
 
Elevator/Rudder Balance

If your going to check the tail group thoroughly than a elevator/rudder balance check would be prudent.Did you or the builder check it when it was built? Was it checked after paint?
R.Hill
 
Shake the Elevators - TOGETHER!

I flew both the RV-3 and V-8 today - but not before getting out a flashlight and inspection mirror and doing a thorough examination of hinge points and fasteners. The -3 passed with flying colors. The -8....well, that was a surprise. Like most pilots, during preflight, I grab the elevator and give it a wag and a shake, then move on to the other one. Today, since I was doing a very THOROUGH job, I notice a little bit of a (tiny) clunk when I moved the left side. I moved to the right, and got the same feel. I then grabbed both of them - and they moved about 1 degree relative to each other !!

Obviously, the inspection covers came off, and I found that the bolt holding the two arms to the push rod was a little loose, allowing relative motion. Obviously, I replace things and tightened back to spec. Yes, this is one of those "Jesus Bolts" sprinkled throughout the airframe. The airplane is 3 months from the next condition inspection - but I took the time to inspect ALL of the visible control and hinge bolts today.

Remember, Condition Inspections are like medicals - they only prove that things were OK on the day they were signed off. I am shocked to find this on an airplane we fly numerous times a week. From now on, I'll be grabbing BOTH elevators at the same time during preflight - hope this gets a few other folks to inspect as well.

No cracks by the way...

Paul
 
Extra bolt

I flew both the RV-3 and V-8 today - but not before getting out a flashlight and inspection mirror and doing a thorough examination of hinge points and fasteners. The -3 passed with flying colors. The -8....well, that was a surprise. Like most pilots, during preflight, I grab the elevator and give it a wag and a shake, then move on to the other one. Today, since I was doing a very THOROUGH job, I notice a little bit of a (tiny) clunk when I moved the left side. I moved to the right, and got the same feel. I then grabbed both of them - and they moved about 1 degree relative to each other !!

Obviously, the inspection covers came off, and I found that the bolt holding the two arms to the push rod was a little loose, allowing relative motion. Obviously, I replace things and tightened back to spec. Yes, this is one of those "Jesus Bolts" sprinkled throughout the airframe. The airplane is 3 months from the next condition inspection - but I took the time to inspect ALL of the visible control and hinge bolts today.

Remember, Condition Inspections are like medicals - they only prove that things were OK on the day they were signed off. I am shocked to find this on an airplane we fly numerous times a week. From now on, I'll be grabbing BOTH elevators at the same time during preflight - hope this gets a few other folks to inspect as well.

No cracks by the way...

Paul


Paul,
This is why I install an extra AN3 bolt and spacer between the two elevator horns securing the two elevators together in addition to the rod end bolt.
Ryan
 
Gently push your elevators and rudder to the stops, and then GENTLY place some more load on the surface with your hand and watch what happens to the spar in the hinge areas. It was never designed to accept that load, especially repeatedly which happens if you park it out on gusty day and allow the wind to load the control against the stops.
 
Gently push your elevators and rudder to the stops, and then GENTLY place some more load on the surface with your hand and watch what happens to the spar in the hinge areas. It was never designed to accept that load, especially repeatedly which happens if you park it out on gusty day and allow the wind to load the control against the stops.

I don't think that is a valid statement.

A full rudder slip is definitely putting the same type of aerodynamic load on the rudder as you are describing (probably more), and full up elevator at 50 MPH during landing rollout is doing the same to the elevators.

Now if you are talking about an RV tied up outside during a hurricane your statement might be valid, but you said gently apply more load...
 
I don't think that is a valid statement.

A full rudder slip is definitely putting the same type of aerodynamic load on the rudder as you are describing (probably more), and full up elevator at 50 MPH during landing rollout is doing the same to the elevators.

Now if you are talking about an RV tied up outside during a hurricane your statement might be valid, but you said gently apply more load...

I'm not so certain about your disagreement. In flight with a full deflection the wind load will be trying to move the surface AWAY from full deflection. In the previous description they were talking about forcing ( gently of course ) PAST full deflection as a wind gust would try to do. I would think that would do significant damage in gusty winds like Hyabusa was trying to describe. ( Think of a hyper extended knee, significant damage ) I also think this might allow you to see if there is flex on the spar. It might also allow you to see a minuscule crack open up that could not be seen without a load applied.

Mark
 
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I write this only as another angle to consider and mean no disrespect to the community here.
If you gently push your elevators and rudder to the stops, and then GENTLY place some more load on the surface with your hand and watch what happens to the spar in the hinge areas, you can see where the stress goes when the control surface tries to pivot against the stop but it can`t.
(In my opinion) It was never designed to accept that load - which happens if you park it out on gusty day and allow the strong buffeting winds to load the control against the stops repeatedly, or worse, bang away until the stop breaks off. In flight, aerodynamic load is developed across the surface and transferred through all the hinge points as intended, but not so when the stop comes into play and tries to act as a pivot point.

The aircraft in this thread, and the one that gave rise to it had something thing in common.

The one in this thread was left out in the wind as stated by the owner. This may, or may not have contributed to the crack.
The other aircraft was also, and the details are in this thread.
http://www.vansairforce.com/community/showthread.php?t=97775
 
Here's a good example of a crack, most appear as a very fine line eminating from a bolt hole, rivet hole or radius/bend line. It will generally appear as a VERY fine pencil line or small crack in the paint. As shown in this pic, it's easy to mistake or overlook a crack that is just starting out as there is no seperation of the material which is what most folks consider a "crack", in the begining it's just a very fine "line".

FB_02_12-17.jpg


I WILL BE HAPPY TO DO FREE TAIL INSPECTIONS TO ANYONE THAT STOP BY MY HANGER
 
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This morning I removed the empennage fairing and inspected the elevator and rudder attach points, rod-end bearings, the HS and VS attach points.

No cracks, loose bolts, loose jam nuts, etc. were found. The torque seals were all unbroken. (Edit: My -9 is approaching 500TT.)

However, while inspecting my tail, I remembered something I did when building; rather than drilling those holes to final size, I drilled them undersize, reamed them to final size, and then deburred both sides of each hole.

Could the cracks be formed in those parts that were simply drilled to final size?
 
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Mark,
A crack like yours doesn't typically occur from a single load event. It is classic of what would be caused by some type of load reversal / flexing across that point. One thing I would be looking for if I were inspecting the airplane, would be hinge axis alignment....If they are (ed; misaligned), the web of the spar would be forced to flex every time the elevator moved on its hinge axis

Good call Scott.

Walt (and others who do a lot of RV condition inspections), are you seeing many cases of hinge misalignment? I recall you have written about poor center bearing shimming.

...I found that the bolt holding the two arms to the push rod was a little loose, allowing relative motion. Obviously, I replace things and tightened back to spec.

Most readers are probably thinking about the possibility of a control disconnect here, but there are additional effects which are more subtle.

The pushrod bolt ties the two elevators together. In the context of flutter prevention, it is a link in a connecting torsional spring formed by the tubular weldments and arms. Torsionally (elevators moving in opposition) a loose bolt reduces the spring rate and/or introduces freeplay, with the potential to reduce the flutter margin in that mode. Is it critical, i.e. likely to actually allow flutter development? I don't know.

I will say this...I like all the margin I can get. Along those lines, I think elevators should be balanced separately, with the pushrod bolt removed, after painting. One elevator is often heavier than the other due to the trim tab and servo. Balancing as an assembly means the heavy elevator relies on the opposite lead weight for mass balance, acting through the torsional spring of the connecting members.

Set flutter aside and consider the ordinary effect of a single trim tab. When deflected it applies force to the attached elevator, which in turn applies force to the other elevator through an asymmetrical load on the pushrod bolt. RV-8's routinely require full up trim when landing solo.

Paul,
This is why I install an extra AN3 bolt and spacer between the two elevator horns securing the two elevators together in addition to the rod end bolt.
Ryan

A fine idea...positive effect, very low risk.
 
Recheck torques on ALL critical fasteners often.

Most builders like to use a lot of paint to protect their aluminum. Many of our parts already come with a nice thick powder coating applied. When we torque a fastener approximately 55% of the torque applied is to overcome nutface friction, 30% thread friction and the remaining 15% to stretch or pre-load the bolt. Over time, our paint beneath the nut/washer/bolthead decreases in thickness which contributes to loose fasteners. I applied lock-tite to my rudder/elevator hinge rod-end jam nuts and to pushrod jam nuts to prevent any further loosening as they are not self locking. We still want to recheck all of these on every condition inspection or before.
 
Paul,
This is why I install an extra AN3 bolt and spacer between the two elevator horns securing the two elevators together in addition to the rod end bolt.
Ryan

Yes, why did I not think of that. Good idea. I always check for movement between my two elevator halves on pre-flight. Our trim tabs on the -10 do not move together at times which can induce a twisting moment. I think about that little -3 bolt on every preflight as I hope don't ever need to do a "trim" landing.
 
I'm not so certain about your disagreement. In flight with a full deflection the wind load will be trying to move the surface AWAY from full deflection. In the previous description they were talking about forcing ( gently of course ) PAST full deflection as a wind gust would try to do. I would think that would do significant damage in gusty winds like Hyabusa was trying to describe. ( Think of a hyper extended knee, significant damage ) I also think this might allow you to see if there is flex on the spar. It might also allow you to see a minuscule crack open up that could not be seen without a load applied.

Mark

I write this only as another angle to consider and mean no disrespect to the community here.
If you gently push your elevators and rudder to the stops, and then GENTLY place some more load on the surface with your hand and watch what happens to the spar in the hinge areas, you can see where the stress goes when the control surface tries to pivot against the stop but it can`t.
(In my opinion) It was never designed to accept that load - which happens if you park it out on gusty day and allow the strong buffeting winds to load the control against the stops repeatedly, or worse, bang away until the stop breaks off. In flight, aerodynamic load is developed across the surface and transferred through all the hinge points as intended, but not so when the stop comes into play and tries to act as a pivot point.

The aircraft in this thread, and the one that gave rise to it had something thing in common.

The one in this thread was left out in the wind as stated by the owner. This may, or may not have contributed to the crack.
The other aircraft was also, and the details are in this thread.
http://www.vansairforce.com/community/showthread.php?t=97775

It is all about where the restraint point is. Since the control activation point (cable on the horn, for the rudder; and push/pull rod on the elevators) is for all practical purposes, at the same location along the span of the control surface as the control stop, the loads in flight at full deflection will be similar to the load application you are describing. True, it will be in the opposite direction, but the same as if in your example you move the surface to the opposite stop and pushed the other way.

There is only one way that loads cause by wind gusts while tied down on the ground are different than would likely be induced in flight. That is the dynamic loads caused by the inertia of the counter balance weight(s) on an unrestrained control surface that is banging against the stops in the wind.
The reason that is different is because the inertia of the balance weight can cause a much higher torsional load than would likely ever be induced in flight. The loads caused by wind forces alone would be acting on the entire surface (along the full span)and not causing an appreciable torsional load.

So, if your concern was a surface banging against the control stops, then I agree with you. If it was just wind loads pushing on a restrained control surface, it is not an issue, and no different than the loads experienced in flight.
 
I've inspected quite a few Cessna's that had looseness between the two elevators. On them (usually 182's) its usually loose rivets on the spar. Pulling the elevators in opposition is something I always do on preflight. That,s how you learn, one creak at a time.
 
... remove[d] the empennage faring and inspect (Put a wrench) on all the bolts back there and look closely (using a magnifying glass) at the VS attach brace.
... look at the HS spar, as described in this thread.

Excellent precautionary move. I just did that as part of my first annual a couple weeks ago ... all was OK. (only 85hrs TT, but nice to see just the same)
 
I went to the hanger to inspect mine and at first glance I saw what appeared to be a similar crack but upon closer inspection with a magnifying glass, it was a mark in the paint (perhaps as a result of the wrench on the nut)

Is there a good way to detect crack short of removing the part?
 
Hoz Spar

Due to the recent loss of a VAF'er I decided to inspect my empennage very carefully.

I found a crack in the right elevator spar at the outboard attach point.
This is how it looked upon inspection. Just a black line.

P1130051.jpg


I wiped the black off the left side but you can still see the crack below.

20130921_095223.jpg


And here it is after the dye penetrant test.

20130921_130940.jpg


It's an RV7A serial number 72183 with 908 hours.

Everyone please check your elevators carefully before your next flight!

Mark
================================
Mark thank you for an excellent post.

My knee-jerk response comes from looking at the pictures:
1 - In the first picture the crack looks like it is radiating from the rivet hole. This could be from:
a> None or incomplete de-burring of the rivet hole.
b> Too small a rivet hole as the rivet is stressing the hole from the inside.
c> Too big a rivet hole.
2 - Second picture: The dye penatrent is showing up around the nut and looks like it is even under the nut. This could be because:
a> Loss of chromate conversion protection in the area.
b> Movement of the nut - YET! It is only on one side so I doubt that is the issue.
c> Something in the order of Hard Dirt under the nut causing a stress point.
AHA! I also notice your 'witness mark' and that is looking good - So not a loose nut.
2 - In the second picture:
Notice the crescent shape of the dye. this indicates:
a> Uneven stresses across an area. It could be as unusual as the grain of the aluminum.
b> What is behind that area?
c> Sure looks like a Double is required in this area - Maybe an inner and an outer.

Please keep all of us posted with your findings and pictures.

Thank you very much for taking the time and effort.

Barry
PS:
Send your information to Van's
 
I don't know if it was already addressed in the previous posts, but it is VERY important that the bolts slide in freely when you attach the rod-end to the the hinge bracket. Any "pre-load" could/will eventually lead to a crack. From what I see from the photo, I would suspect that as a possible cause.
 
stab spar cracks

First time user RV7A n838wt After the accident last week in NJ that looked like a structural failure of the rudder or elevator. The postings on stab cracks caused me to check my plane and I found a couple of lock nuts that need tightening . Thanks guys:)
 
This is why the jam nuts are there

A loose jam nut could be the cause of such a crack, if the jam nut is loose the nutplate and nutplate rivets are carrying the full load of the fitting.

FYI - I find loose jam nuts on elevators and rudders routinely :eek:

PS: good find, everyone should inspect this area at the earliest opportunity.

Thanks for this post .. I wondered why the jam nut was there on the HS an VS rod end bearings. The darn thing's not gonna turn once the control surface is hung, and I had though that they were a bit superfluous.. Transferring the load to the spar is critical!
 
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The rivets on the ears of the nutplates are there to keep the nutplate from turning - that's it. A rod end with loose or missing jamnuts is passing the entire load through those two #40 rivets... Much higher load than they are designed for. When they break, you have a control surface just flopping around back there. Bad news.
 
HINGES

Two things I haven't seen addressed:
Lateral alignment of hinges-does the channel portion align perfectly with the rod end. If one part is slightly misaligned with the mating part in an inboard -outboard orientation, if the parts must be forced together for elevator installation, this is not acceptable.
Channel fit on rod end inner race: if the rod end bearing is not a perfect fit in the channel, shim washers should be used to obtain a snug fit.

Regarding the post about Cessna's, on nearly ALL twin Cessna's the elevators can be moved in opposite directions at the trailing edge.
 
Two things I haven't seen addressed:
Lateral alignment of hinges-does the channel portion align perfectly with the rod end. If one part is slightly misaligned with the mating part in an inboard -outboard orientation, if the parts must be forced together for elevator installation, this is not acceptable.
Channel fit on rod end inner race: if the rod end bearing is not a perfect fit in the channel, shim washers should be used to obtain a snug fit.

Regarding the post about Cessna's, on nearly ALL twin Cessna's the elevators can be moved in opposite directions at the trailing edge.

It's been a long time since I've built the HS, but aren't these prepunched holes?
 
Holes

My understanding of the RV7 is that the holes are pre punched, but this does not absolutely eliminate the possibility of hinge misalignment, especially if there is damage history.
Also if the pre punched holes are so error proof, why has there been so much discussion about hinge alignment problems??
 
Checked mine tonight. No cracks. But all four jam nuts on the elevators needed about 1/2 turn...
 
Good call Scott.

Walt (and others who do a lot of RV condition inspections), are you seeing many cases of hinge misalignment? I recall you have written about poor center bearing shimming.

There is no way to check for hinge misalignment without removing the attach bolts which I do not nomally do. If I find a stiff surface I always dig until I find out why and in a few cases I did have to remove an elevator/rudder and readjust the rod ends to get things right.

Improper shimming of the center bearing is common and easily deterimined. If the hinge bolts are not torqued and torquing them up locks up the elevator then the center bearing is not shimmed properly.
 
Improper shimming of the center bearing is common and easily determined. If the hinge bolts are not torqued and torquing them up locks up the elevator then the center bearing is not shimmed properly.

Also, if the hinge bolts are torqued, and you force control horns together with the pushrod bolt just a little bit, it can make the elevator drag and not move freely. Happened to me after re-assembly when the plane was painted.

Bottom line here is check, and double check.
 
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Also, if the hinge bolts are torqued, and you force control horns together with the pushrod bolt just a little bit, it can make the elevator drag and not move freely. Happened to me after re-assembly when the plane was painted.

Bottom line here is check, and double check.

Agree Mike, without proper spacers in between the horns, tightening the bolts will apply a bending force to the horns also causing binding. This problem doesn't seem to be as common as center bearing binding probably because it's not quite as critical and its relatively easy access compared to the center bearing.
 
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Checked mine tonight. No cracks. But all four jam nuts on the elevators needed about 1/2 turn...

Since this seems to occur once in a while, and maybe more often than that, are these things loosening in flight?

I noticed on my RV-3B that the nuts aren't self-locking and they aren't drilled for safety wiring. Should we be using Loctite or something?

Dave
 
Since this seems to occur once in a while, and maybe more often than that, are these things loosening in flight?

I noticed on my RV-3B that the nuts aren't self-locking and they aren't drilled for safety wiring. Should we be using Loctite or something?

Dave

I used blue loctite on mine plus some torque seal. No apparent movement in 100 hours.
 
Inspecting

So Walt, may I come by your hangar this week, Thurs early before I go to work and take some pictures of what I should be looking for exactly. My plane is in Tucson and I'd like to look at it closely when I get back home Friday.

I would sure appreciate you showing me on another RV.
 
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