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SB-00036 posted: Inspect outboard elev hinge bracket area of most RV models

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Brian if it were me, I'd go ahead and order the new hinge brackets from Van's and install those instead since you have that option. All the new kits going forward will use these new brackets apparently.

But are there new parts for the -14? (Or 3/9/10)
 
I recently purchased this inexpensive version from Teslong. The camera is only .2 inches in diameter and it has a tip camera and a side camera. The side camera makes it very easy To inspect valve faces inside of cylinders, and the it would work perfect for the horizontal stab inspection. I am amazed at the resolution compared to the Vividia 400 that we have used in the shop for many years and it doesn’t require an additional computer device to view the camera.

https://www.amazon.com/gp/aw/d/B09YGNWL44/ref=ya_aw_od_pi?ie=UTF8&psc=1

This is the same scope I have. I did the SB inspection today and it worked very well with excellent resolution. No cracks of course - only 50 hours on the plane so far and in the paint shop, so inspection was very quick and easy with the elevators off. Th hinge brackets on my tail are very straight, with no binding or force required while inserting the hinge bolts - a very important detail when considering a load on those outboard hinge brackets. Build it straight and you’ll probably never have a problem.
 
But are there new parts for the -14? (Or 3/9/10)

I heard from Vans tech support this afternoon. They are prototyping new parts for the 9/10/14. Once proven, they will be released to production. No date estimate at this time.
 
I am building my -10 HS currently and also reached out to support with a similar reply. Interestingly, they are not recommending preventative action on the 9/10/14. Since I have not riveted my brackets yet, I will wait for the parts and do it anyway.

Full response:

Regarding SB-00036 for RV-9/10/14 airframes. We will be doing a revision to SB-00063 for the outboard elevator hinge brackets. One will be adding new brackets parts applicable to the 9/10/14 models. Brackets for these aircraft are working through prototyping then will be released for production once proven. We don’t have a manufacturing completion date for those yet.



If you are still building your horizontal stabilizer you can wait for these to be produced if you wish to. If your horizontal stabilizer is completed we however do not recommend it be done preventatively on these models as they are very low risk to be effected by this.
 
Greg, I am literally a few days away from finishing my HS. The HS rear spar is complete and primed, but not installed in the skin. What is the guidance for those who have the emp kit and haven’t built the HS yet? Will you guys send parts for the mod? Should I wait to finish HS pending new hinge brackets? It seems logical to install the new brackets now before assembling the HS.

Brian Robbins
RV14

Assuming you're talking about your RV-14 build, the parts available as of today are not for that model. We will be releasing parts for the 9, 10 an 14 models in the not-too-distant future. I do not have a date yet for those.

Sorry, juggling a lot of cats right now so my replies are pretty slow.
 
But are there new parts for the -14? (Or 3/9/10)

I heard from Vans tech support this afternoon. They are prototyping new parts for the 9/10/14. Once proven, they will be released to production. No date estimate at this time.

Correct. We are working on parts for the 9, 10 and 14 models. We will revise the service bulletin as soon as those are ready.

The RV-3 is a much less standard aircraft due simply to the age and variability of the design/build process.

I am building my -10 HS currently and also reached out to support with a similar reply. Interestingly, they are not recommending preventative action on the 9/10/14. Since I have not riveted my brackets yet, I will wait for the parts and do it anyway.

That makes good sense. And, it is the choice of the owner when to make the change - now/proactively or in the future with inspections until then.

Greg,

Thanks for the detailed response and transparency. I know you're extremely busy and I appreciate you taking the time to respond. Appreciate it.

As I mentioned in my post, I understand that all the models listed in the SB may be susceptible to cracking due to the similarity of the design and their normal flight environment. Hopefully no one will take this SB lightly. (emphasis added)

Thanks Carl. We take safety very seriously and work hard to be as transparent as possible. And, I appreciate your post. Our position is always that people should not ignore or avoid service bulletins and similar publications. We publish them only when there is a reason to do so. It can be inconvenient, we certainly realize that, but airplane ownership - while always very worthwhile - can't always be convenient. We'd much rather do what we can to help ensure everyone is safe, if the choice we have to make is between safety and not being inconvenienced. Everyone's safety and prevention of potential problems is first. :cool:
 
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I just did this inspection on an RV-4. I found that with my particular borescope, the tooling hole is closer the spar than would be optimal for the articulating bend radius of the scope. A new hole, an inch or two forward of the aft tooling hole would be much better. Of course YMMV, depending upon the scope being used.
A new hole might just be the ticket for the "glassed in" crowd.
 
This SB kind of begs the question: what about the elevator spar at the same hinge location?

The hinge loads are approximately equal in the two surfaces. If the loads are high enough to cause issues with the stabilizer spar, one might think they would also be a problem for the elevator spar.

It may be that the root problem here is not the aero load, but rather loads imparted by less than perfectly aligned hinges? If so, then one would expect the problem to show in the elevator spar as well.

It may be that the flexibility of the rod-bearing hinge provides a sort of 'suspension' that may shield the elevator spar from peak loads?

Not sure it is even possible to know the answer to this. But should we be thinking about a elevator spar reinforcement at the same place?
 
This SB kind of begs the question: what about the elevator spar at the same hinge location?

The hinge loads are approximately equal in the two surfaces. If the loads are high enough to cause issues with the stabilizer spar, one might think they would also be a problem for the elevator spar.

It may be that the root problem here is not the aero load, but rather loads imparted by less than perfectly aligned hinges? If so, then one would expect the problem to show in the elevator spar as well.

It may be that the flexibility of the rod-bearing hinge provides a sort of 'suspension' that may shield the elevator spar from peak loads?

Not sure it is even possible to know the answer to this. But should we be thinking about an elevator spar reinforcement at the same place?

I think SB 14-02-05, "Cracking in elevator spar web near elevator attach points.", covers your concern, at least for the RV-3, -6/6A, -7/7A, and the -8/8A:



Also note on Page 5: "NOTE: Misalignment of a rod end relative to the overall hinge line of the elevator can contribute to cracking near the misaligned rod end."
 
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I think SB 14-02-05, "Cracking in elevator spar web near elevator attach points.", may cover your concern, at least for the RV-3, -6/6A, -7/7A, and the -8/8A:


Yes it does. But the fix is quite different. In the current case, an effort is made to distribute the hinge loads out into the spar flange and skin directly. On the elevator, just a local doubler is added.

On the stabilizer hinge bracket, the foot of the bracket is already large, distributing the load over a fairly big area (unlike the elevator) acting like a doubler. Yet those are cracking. So is the SB 14-02-05 doubler adequate?
 
Yes it does. But the fix is quite different. In the current case, an effort is made to distribute the hinge loads out into the spar flange and skin directly. On the elevator, just a local doubler is added.

On the stabilizer hinge bracket, the foot of the bracket is already large, distributing the load over a fairly big area (unlike the elevator) acting like a doubler. Yet those are cracking. So is the SB 14-02-05 doubler adequate?

Yep, I understand that the fix is different. And I see your point.

Is the SB adequate? Only time will tell I guess.
 
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Yep, I understand that the fix is different. And I see your point.

Is the SB adequate? Only time will tell I guess.

The good news is that with the size of the RV fleet and all doing “proper” inspections, we will find out and address issues before they become catastrophic. Please, everyone, if you find a crack, report it to Vans so they can understand the breadth of the issue.
I have always done a thorough inspection of tail hinge fittings at condition inspections even before any of the SBs have been released. Control surface Hinge fittings are always flight critical and typically places of cracks forming in many airplane models.

Yeah, I really hate the idea of even enlarging the hole that's there on my fully painted plane, just to do this inspection. Wish there were a better way (or a smaller diameter borescope LOL!).

Always good practice to allow inspection access to both sides of safety critical fittings.
 
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Theory vs practice.

This SB kind of begs the question: what about the elevator spar at the same hinge location?

The hinge loads are approximately equal in the two surfaces. If the loads are high enough to cause issues with the stabilizer spar, one might think they would also be a problem for the elevator spar.

It may be that the root problem here is not the aero load, but rather loads imparted by less than perfectly aligned hinges? If so, then one would expect the problem to show in the elevator spar as well.

It may be that the flexibility of the rod-bearing hinge provides a sort of 'suspension' that may shield the elevator spar from peak loads?

Not sure it is even possible to know the answer to this. But should we be thinking about a elevator spar reinforcement at the same place?

I think SB 14-02-05, "Cracking in elevator spar web near elevator attach points.", covers your concern, at least for the RV-3, -6/6A, -7/7A, and the -8/8A:



Also note on Page 5: "NOTE: Misalignment of a rod end relative to the overall hinge line of the elevator can contribute to cracking near the misaligned rod end."

Yes it does. But the fix is quite different. In the current case, an effort is made to distribute the hinge loads out into the spar flange and skin directly. On the elevator, just a local doubler is added.

On the stabilizer hinge bracket, the foot of the bracket is already large, distributing the load over a fairly big area (unlike the elevator) acting like a doubler. Yet those are cracking. So is the SB 14-02-05 doubler adequate?

Steve the brackets seem to be loaded via the rod eye ball primarily parallel to the plane of the bracket. This means load reactions are tension on the rivets or compression on the flanges against the spar web. Although the flanges are stiff, I don't see any doubling effect as the tension loads still go directly into the spar resulting in the entire web tending to flex from that loading. Since the cracks mostly seem to be on the top for #1 photo - that one might be the aerobatic loads. But chop and general vibration would affect the upper and lower rivets similarly with less of an offset/bias to the uppers. The second photo might represent that loading - i.e a cruise condition.

Yep, I understand that the fix is different. And I see your point.

Is the SB adequate? Only time will tell I guess.

I wondered about that elevator doubler when it was released - - and why it did not have a flange to send a bending load into a tension area of the spar flange and skin. As Steve has pointed out - the loads are equal. The elevator was stiffened and now the HS spar is being stiffened. I say good, but design practice says match the stiffness or one will take all the strain energy.

Now- I would assume that Vans has taken this into account and a stiffness model of both surfaces has been matched for this result via FEA - it would be good to hear that from Vans, and not just assume as the design philosophy is different. . Otherwise, we (collectively) are attacking a cascade of symptoms and not the fundamental problem.

Even if the web bending (w/doubler) of the elevator is redesigned with a flange to share that load with the skin, the basic issue of the loading of that pivot may transfer it to the inner pivots. After all - the elevator, horns and spars all share the same loads generated by area loading via the pivots.

Right to modify this post is reserved.
 
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Hey Greg, thank you all for investigating and coming up with a fix. I know there is a “don’t combine orders” . But, would it be possible for you all to throw the SB into my finish kit crate when it ships in a couple months? Hopefully avoiding paying another shipping charge across the country.
 
There are at least three aircraft that we are aware of so far where the cracking described in the SB have been found. I first want to be very clear that we do not believe this potential issue is specific to an individual model, even though the models I am about to describe are all RV-7s. But, since you asked: Two of the aircraft we are aware of at this time are RV-7s that have been operated for around 2,000 hours each. The photos you see in the service bulletins are from those aircraft. The RV-7 that Mike Seager flies (477RV) for factory transition training has been inspected and does not have cracks. That airplane has more than 6,000 hours. Our RV-7A demonstrator aircraft was inspected and did have the cracks. That airplane has about 2,650 hours of accumulated time. Based on what we have seen so far, using time in service or making assumptions about how it was operated (which really is all subjectively relative) should not be used to determine whether or not this bulletin is more or less important. Inspect and verify, and of course fix when needed, is our firm direction.

The massive difference in hours between these aircraft with the higher hour aircraft not cracked is interesting. This can only mean differences exist that are a direct contributor to cracking. A list might include. Build quality, de burring, riveting….possibility of direction of installed rivets with shop heads on the inside against the thinner material?, quality of material, flight loads including regularity of aerobatics, g loading, turbulence and vibration, or my favourite….misaligned hinges…..because if hinges are misaligned there will be constant working of the hinge….something has to give and it will be the material around the rivets on the spar….with one aircraft at 6000 hours no cracks….others at 2000……mmmm
 
9 HS - Elevator?

I am having a difficult time figuring out what to inspect on for this SB. The Outboard Hinge Bracket for the 9 is HS 912 and in this SB it is listing HP 413PP.

Is that the number for the 7 and 8? I am also not sure if I am inspecting the rear spar of the HS or the spar on the Elevator. The HS spar is easily visible through lightening holes but the inside spar of the Elevator will need a bigger hole.

Since this is just an inspect for the 9-10, is that why the numbers and pictures do not match? If the spar on either need to be replaced it is going to be quite a bit of work.
 
I am having a difficult time figuring out what to inspect on for this SB. The Outboard Hinge Bracket for the 9 is HS 912 and in this SB it is listing HP 413PP.

Is that the number for the 7 and 8? I am also not sure if I am inspecting the rear spar of the HS or the spar on the Elevator. The HS spar is easily visible through lightening holes but the inside spar of the Elevator will need a bigger hole.

Since this is just an inspect for the 9-10, is that why the numbers and pictures do not match? If the spar on either need to be replaced it is going to be quite a bit of work.

This SB is for the outer most hinge brackets on the horizontal stabiliser. The ones that only go through the spar. The others are not affected as they also go through the heavy doublers however the outer ones don’t.
 
Tooling hole

Greg, I don’t see the 6 mentioned in your post #42, is this an over sight or are there not tooling holes on the 6?

Thanks, Al
 
This is the same scope I have. I did the SB inspection today and it worked very well with excellent resolution. No cracks of course - only 50 hours on the plane so far and in the paint shop, so inspection was very quick and easy with the elevators off. Th hinge brackets on my tail are very straight, with no binding or force required while inserting the hinge bolts - a very important detail when considering a load on those outboard hinge brackets. Build it straight and you’ll probably never have a problem.

This is only a part of the alignment - just because the bolts go in easily does not mean there are not problems with alignment. The bolts should all move freely (prior to putting nuts on, obviously) with the elevator at the extreme up and down positions.

The key, as Scott wrote (quoted above) is that everything be in a straight line. I just wanted to point out that bolts going in easily does not confirm this.
 
There are at least three aircraft that we are aware of so far where the cracking described in the SB have been found. I first want to be very clear that we do not believe this potential issue is specific to an individual model, even though the models I am about to describe are all RV-7s. But, since you asked: Two of the aircraft we are aware of at this time are RV-7s that have been operated for around 2,000 hours each. The photos you see in the service bulletins are from those aircraft. The RV-7 that Mike Seager flies (477RV) for factory transition training has been inspected and does not have cracks. That airplane has more than 6,000 hours. Our RV-7A demonstrator aircraft was inspected and did have the cracks. That airplane has about 2,650 hours of accumulated time. Based on what we have seen so far, using time in service or making assumptions about how it was operated (which really is all subjectively relative) should not be used to determine whether or not this bulletin is more or less important. Inspect and verify, and of course fix when needed, is our firm direction.

Commonalities- the 3 photos in the SB show the shop head of the rivet on the forward side (spar) instead of the hinge bracket. Out of curiosity since a crack was found on the demonstrator, how is the rivet oriented?
 
I was wondering the same thing Webb… on my 7A, the shop heads are on the aft side, (on the hinge bracket)….
The plans show the rivets orientation as seen in the photos…..
 
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Commonalities- the 3 photos in the SB show the shop head of the rivet on the forward side (spar) instead of the hinge bracket. Out of curiosity since a crack was found on the demonstrator, how is the rivet oriented?

I was wondering the same thing Webb… on my 7A, the shop heads are on the aft side, (on the hinge bracket)….
The plans show the rivets orientation as seen in the photos…..

I strongly doubt that is would make much difference.
The spar web material is still going to lever/flex on the edge of the rivet head from load cycles regardless of which style rivet head it is levering on.
 
This tooling hole...
 

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RV-4 H.S. Inspection

I was able to drill through my filled end rib and intersect the tooling hole using Greg’s measurements without much difficulty. After careful inspection no cracks. My 4 is 24 years old with aprox 1500 hrs. Back in the day we fabricated our own hinges out of aluminum angle long before Vans supplied the prefabricated steel ones. I would be interested in knowing if this variable would have any bearing on the spar cracking. On my HS-13 hinges we also used 5 rivets instead of the 4 shown in Greg’s examples, with the additional rivet centered between the other 4. Intuitively this setup seems more robust with possibly less flexing of the spar web ? Anybody find cracking with the old style hinge ?
Duff
 
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Match drilling non pre punched brackets

I started a new thread with this but it is really more relevant here.

So this is an elementary question, but on the HS SB00036 on a non pre punched spar, what is the process to match drill the new (non PP) hinge brackets to the existing spar holes if you are not removing the skins?

Is it acceptable (and this is an engineering question) to put new holes 90* from the existing ones and abandon the old holes? Or move the new holes sideways with proper edge distance from the old holes?
 

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Is it acceptable (and this is an engineering question) to put new holes 90* from the existing ones and abandon the old holes? Or move the new holes sideways with proper edge distance from the old holes?

Your first option is definitely not acceptable, in my opinion. All the load goes through the corner fasteners and reacts into the skin. Your option drops from 2 rivets down to one rivet to take the load.
 
I started a new thread with this but it is really more relevant here.

So this is an elementary question, but on the HS SB00036 on a non pre punched spar, what is the process to match drill the new (non PP) hinge brackets to the existing spar holes if you are not removing the skins?

Make a Jig. Go get a small length of 3 x 3 angle (or whatever fits). Clamp the hinge into the jig and match drill the bearing bolt hole then match drill the four rivet holes. Put the new hinge in the jig and match the bearing hole to the jig with a 3/16" rod (be sure it is square-may need small shims) and clamp. Match drill rivet holes from the back side of jig.

Instead of the large angle, you could take two sheets or bars and clamp both to some square stock or small angle stock. Making a jig like this is pretty simple with scrap material. No wood though, as it is too soft for match drilling. When match drilling, you need a fairly hard material to hold the bit while it starts the new hole. An exception would be using centering bits on a drill press with work clamped to the table.
 
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Make a Jig. Go get a small length of 3 x 3 angle (or whatever fits). Clamp the hinge into the jig and match drill the bearing bolt hole then match drill the four rivet holes. Put the new hinge in the jig and match the bearing hole to the jig with a 3/16" rod (be sure it is square-may need small shims) and clamp. Match drill rivet holes from the back side of jig.

Instead of the large angle, you could take two sheets or bars and clamp both to some square stock or small angle stock. Making a jig like this is pretty simple with scrap material. No wood though, as it is too soft for match drilling. When match drilling, you need a fairly hard material to hold the bit while it starts the new hole. An exception would be using centering bits on a drill press with work clamped to the table.

This is an outstanding idea, well-explained. It is a good general trick to keep in the 'tool box'.
 
Make a Jig. Go get a small length of 3 x 3 angle (or whatever fits). Clamp the hinge into the jig and match drill the bearing bolt hole then match drill the four rivet holes. Put the new hinge in the jig and match the bearing hole to the jig with a 3/16" rod (be sure it is square-may need small shims) and clamp. Match drill rivet holes from the back side of jig.

Instead of the large angle, you could take two sheets or bars and clamp both to some square stock or small angle stock. Making a jig like this is pretty simple with scrap material. No wood though, as it is too soft for match drilling. When match drilling, you need a fairly hard material to hold the bit while it starts the new hole. An exception would be using centering bits on a drill press with work clamped to the table.

This is exactly what I needed. Very simple and precise. Thank you!
 
Much like the HS forward Spar SB, I absolutely will not be replacing my hinges until there is a problem, or a definitive reason is found, not the conjecture so common when this kind of problem arises here. We don't know the cause of the problem. The engineered fix seems logical, but until enough hours and time are put into play, we don't even know if it is the final fix.
No tails have fallen off, even as bad as the one example in the SB appears to be. If folks are adhering to the inspection requirements called out in the SB, the issue should show itself way before there is a serious issue.
If I do find the issue in the future (mine looks like the day it was new) I will replace the spar and do whatever fix has been tested. By then, if it happens, I believe we will know a lot more.
I subscribe to "Don't fix it if it ain't broke" unless it is inevitable and might leave me stranded somewhere. I would be putting the new hinges on a new build, even if I had to unzip the skins to do it. Not a big fan of the cherry max fix, even though I can't come up with a good reason why, just me.

(The match drill technique described is very good and I have done similar in the past with good results, so, if you absolutely need to replace the hinges just because, at least you have the talent here to guide you.)
 
I did the inspection on an rv4 today. The aft tooling hole was unreachable with the elevator installed. I drilled a hole aft of the fwd elevator spar to insert the borescope. Most of the airplanes around here are filled and fiberglassed. I have little faith that the tooling hole could be located accurately under foam and glass. This particular airplane has doubler plates installed. Somebody was thinking ahead and i doubt it would ever crack. I have 5 more to do this week. I am also drilling and inspecting my harmon rocket.
 

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Contributing Factor?

Not an engineer here but..
Could a contributing factor on the hinge loads be related to elevator mis-alignment?
Going off memory here.. When match drilling the elevator horns, we clamp the counterbalance arm leading edges to the horizontal stab. What if the elevators are not in alignment when the horns are drilled? Could this mis-alignment cause cause extra forces during flight. Seems like the bolts where the elevator horns are connected along with the outer hinge brackets would absorb these loads and, out of those two, the outer hinges would lose.
I remember when I clamped the counterbalance arms to the horizontal stab, the elevator trailing edges were slightly off. I opted to align the elevator surfaces, average between the the two, and accept the slight difference in the counterbalance arms in relation to HS. I.E., one was 1/8" up and one was 1/8" down.
I have to use exaggeration sometimes. Imagine split between left/right elevator is 3". Imagine the air loads trying to streamline the two. Forces would be on the AN3 bolt connecting the elevator horns and the outer hinge pin brackets.
Could account for why some planes with many hours have no issues, and others with fairly low time have cracks.
Is this reasonable?
 
I did the inspection on an rv4 today. The aft tooling hole was unreachable with the elevator installed. I drilled a hole aft of the fwd elevator spar to insert the borescope. Most of the airplanes around here are filled and fiberglassed. I have little faith that the tooling hole could be located accurately under foam and glass. This particular airplane has doubler plates installed. Somebody was thinking ahead and i doubt it would ever crack. I have 5 more to do this week. I am also drilling and inspecting my harmon rocket.

Noticed on your photo this particular RV4 has the 5th center rivet as mentioned on the last page by Duff, wondering how common this might be or is it just totally builder variance?

Curious if upon inspecting in my 2002 RV7 with 1400h, if there are (hopefully) no issues, if adding a cherry max to that center location might help any possible future issues?

Or would it be worth while to just remove the old bracket and replace with the new one even if no cracks are present to again reduce future potential issues? I ordered the bracket just to have it on hand...
 
Smaller boroscope

Guys,

Just wanted to put this out there. I used the smaller micro boroscope to get an RV7A done this weekend. It allowed me to drill the tooling hole smaller (only 1/4) and the side camera did a great job. The pics show the difference between the articulating boroscope and micro. Just food for thought.
 

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Did the inspection (VA-400, worked fine after the tooling hole was enlarged to 13/32") and found 1 crack, on the right outboard hinge, propagating from the second-from-inboard rivet of the lower 4, horizontal and not even close to the spar radius. Small, but a crack nonetheless (see pic). I ordered the repair kit and I'll do both sides. This RV-6 was completed in 2000, has 1980 hours and has not done much aerobatic flight.
i-Fb3N7kf-Th.jpg
 
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Bucktail of rivets on the thinner weaker piece

There are at least three aircraft that we are aware of so far where the cracking described in the SB have been found. I first want to be very clear that we do not believe this potential issue is specific to an individual model, even though the models I am about to describe are all RV-7s. But, since you asked: Two of the aircraft we are aware of at this time are RV-7s that have been operated for around 2,000 hours each. The photos you see in the service bulletins are from those aircraft. The RV-7 that Mike Seager flies (477RV) for factory transition training has been inspected and does not have cracks. That airplane has more than 6,000 hours. Our RV-7A demonstrator aircraft was inspected and did have the cracks. That airplane has about 2,650 hours of accumulated time. Based on what we have seen so far, using time in service or making assumptions about how it was operated (which really is all subjectively relative) should not be used to determine whether or not this bulletin is more or less important. Inspect and verify, and of course fix when needed, is our firm direction.

Im curious about how these airplanes were assembled. This could apply to the aileron hinge brackets too. The pictures in the SB show the shop head on the web of the spar. Have you ever seen such cracks where the factory head is on the web side. I always avoided placing the bucktail ( shop head) on the the thinner material if at all possible. I think these cracks are as much a manufacturing defect as a fatigue issue or a combination of both. Id like to see a crack from the factory head installed on the web side.

Cm
 
I mentioned this a couple pages back. I have all my shop heads where possible on the thicker material...cant see them very easily when the control surfaces installed and can be a pain to paint I guess....however....it is generally considered the best option when orientating rivets. I do not worry about the aesthetic look in these areas as its a fairly mute point so i put all my shop heads on the doublers or the thickest strongest material....in this case the steel brackets. The shop head has its load spread over a smaller area compared to the manufactured head and one imagines the rivet deforming strongly into the weaker material as the shop head is formed. Id like to see if any aircraft exhibit cracks from this area with the rivets around the other way.
 
I mentioned this a couple pages back. I have all my shop heads where possible on the thicker material...cant see them very easily when the control surfaces installed and can be a pain to paint I guess....however....it is generally considered the best option when orientating rivets. I do not worry about the aesthetic look in these areas as its a fairly mute point so i put all my shop heads on the doublers or the thickest strongest material....in this case the steel brackets. The shop head has its load spread over a smaller area compared to the manufactured head and one imagines the rivet deforming strongly into the weaker material as the shop head is formed. Id like to see if any aircraft exhibit cracks from this area with the rivets around the other way.

Guessing that over 90% of the fleet has shop heads in the interior. With over 10k kits flying, the small number that may exist with shop heads on the hinges would be statistically irrelevant, if a problem was found or not.
 
Are you saying

Guessing that over 90% of the fleet has shop heads in the interior. With over 10k kits flying, the small number that may exist with shop heads on the hinges would be statistically irrelevant, if a problem was found or not.

If 100 percent of the cracked units have the shop head on the inside that would be statistically insignificant?.
My thought is that forming the rivet likely is an issue here.
I will be curious to see.
 
If 100 percent of the cracked units have the shop head on the inside that would be statistically insignificant?.
My thought is that forming the rivet likely is an issue here.
I will be curious to see.

I don’t think enough were built shop head out. Unless a large number of Rv’s develop cracks, it’s too small a number.
 
On the Facebook vans airforce group there is a factory head on the inside with a crack on a RV-8.
 
Guessing that over 90% of the fleet has shop heads in the interior. With over 10k kits flying, the small number that may exist with shop heads on the hinges would be statistically irrelevant, if a problem was found or not.
sheeple maybe? I guess I follow the "best practice":eek: but then i dont know anything. Just seems better to form the shop head on the thicker stuff. Now i see there is an RV8 with a manufactured head on the inside like mine with a crack its not insignificant...might be more....may lead to a different conclusion then....my fav reason still is misalignment of hinges...plus i was a bit surprised those bits were not made with a doubler...
 
So the way I read this is that regardless of cracks or not the brackets are to be replaced anyway but a scheduled inspection is to take place in the mean time till done so?
 
So the way I read this is that regardless of cracks or not the brackets are to be replaced anyway but a scheduled inspection is to take place in the mean time till done so?

You can just keep inspecting it at Annuals and not do the repair until cracks show. If at all. Or you can do the repair before cracks show. One day if you want to sell it I imagine having the SB done will be a bonus even if no cracks.

It says under time of compliance is within 25 hours or the next annual which ever is earlier. Continue this at annuals until the repair is done. Then if no cracks found go to step 9. Step nine is to write in the log book the inspection for the SB has been complied with. No need to replace the bracket yet. I’m going to do it before I finish my rv7….because then it’s done and it will be stronger anyway. Even with cherry max rivets rather than solid rivets.
 
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SB00036

No, the first inspection is required within the next 25 flight hours or the next CI whichever occurs first. If no cracks are found, then re-accomplish the inspection each 12 months until such time that the repair is accomplished at which point the recurring inspection requirement is dropped.
 

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I contend that even if the repair is performed, you should continue to inspect every year. With the tooling hole already enlarged, it takes about 5 minutes to inspect with a borescope. Control surface fittings are safety of flight and historically are prone to cracks, therefore it should already be on your regular inspection routine. Also, the fix has been analyzed to solve the issue but not been proven in field service therefore watching it is prudent.

Note: A borescope has almost become a mandatory tool for anyone maintaining an airplane. There really is no good reason to not have one in your tool box as there are multiple options for ones at reasonable price and they are no more expensive than a good quality wrench or a timing buzz box. Unless you build in removable inspection access panels (like military and commercial airplanes) there are plenty of corners that a borescope needs to be used for a proper routine inspections. (I do not have any affiliation with any company that makes or sells borescopes)
 
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Note: A borescope has almost become a mandatory tool for anyone maintaining an airplane. There really is no good reason to not have one in your tool box as there are multiple options for ones at reasonable price and they are no more expensive than a good quality wrench or a timing buzz box. Unless you build in removable inspection access panels (like military and commercial airplanes) there are plenty of corners that a borescope needs to be used for a proper routine inspections.

I’m persuaded that this is good advice, even though I only do a minimal part of the maintenance on my airplane. I did buy the $100 Teslong mentioned by a previous poster here (delivered tomorrow). My A&P had access to a scope at his previous job but changed jobs recently and now doesn’t have one to use on my airplane. I’ll work with him to use this new one for this SB, but I also have at least a few other uses for this scope in my home/shop so…a reasonable purchase IMHO. At only 0.1 AMU’s, not a major tool investment. It appears to be highly rated, but it’s a Chinese device being sold on Amazon so I’m not sure if those ratings mean anything.
 
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RV9A

It appears the RV9A is exempt from the fix, but must be inspected yearly.

And Vans is working on a modified RV9A bracket but it is not available yet anyway.

Am I correct in this thinking?

Lastly, for a new build, should I note in the aircraft log book that SB was complied with, even thou it hasn't flown?
 
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