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Check those tails

Trust me, like Vic I've seen plenty of tails that were "not per plans", one pre-buy was so bad we grounded the aircraft until I could accomplish a repair.

One thing it does make your realize is how good the engineering is on Van's aircraft, if it wasn't, there probably would be significantly more accidents.
 
1001001 said:
So, as I understand it, the bulk of these have been found during pre-buy inspections or by current owners going out and looking.

I hate to ask, but wouldn't one expect flaws like this to be caught during the initial airworthiness inspection?
Click to expand...

Yes, they should have been. That's why I have a really hard time with DAR's and FSDO inspectors that only care about the paperwork. And quite candidly, some builders shop for DAR's and Inspectors whom they know won't look at the airplane.

And then there are some who really don't have the experience to recognize some of the more subtle errors, such as the improper edge distance. No fault of their own.You really have to know where to look, and it helps to have LOTS of experience on the various types of amateur built aircraft in order to do a thorough inspection.

I have had more than one aircraft come to me that had a prebuy done on them and things like this were missed. No disrespect intended, but just because someone has built one doesn't mean they are qualified to do a prebuy on one. They could have made the same mistake so they don't even recognize them as a mistake on a different airplane.

I need to figure out how to post the talks I did at OSH on builder errors and pre-buys. It should help a lot. I'm just not certain how to do that yet.

Vic
 
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vic syracuse said:
I need to figure out how to post the talks I did at OSH on builder errors and pre-buys. It should help a lot. I'm just not certain how to do that yet.

Vic
Click to expand...

Umm, wow, now there is a valuable offer:) Please, anybody able to help Vic out with this? ... Please.

I'm guessing a lot of folks would benefit from this!!!!
 
Webinar?

Vic,

What about doing an EAA webinar of the presentation you did at OSH?

They're available anytime online and a great resource for review.

I know folks would love to see and hear your thoughts.

Mike Busch has done a ton of them....

Rob
 
You would think that being on Homebuilt Council I would know how to do that! I will look into it.

Vic
 
vic syracuse said:
I need to figure out how to post the talks I did at OSH on builder errors and pre-buys. It should help a lot. I'm just not certain how to do that yet.

Vic
Click to expand...

If you have the video files of them, it would be relatively trivial to post to Youtube. If you didn't want that, I would be able to host them on my web server. I cannot guarantee that they will be indefinitely available, nor that I might not have to take them down due to bandwidth issues, but it might be an interim solution.

I could try to help with this. Maybe I have misunderstood what you're saying above.

Edited to add: the EAA webinar or video solution mentioned above would probably be better overall. But my offer stands.
 
DanH said:
Interesting...the spar is no longer bolted directly to the longeron. It would clamp the longeron quite nicely (in concert with the angle under the deck), if the shim (seen here unpainted under the spar) was extended out to the stabilizer rib.

Colin, what was the material callout for those triangular gussets, notably thickness, and are you sure it is supposed to have both shims and gussets? Seems like having both would raise the leading edge of the stabilizer just a tad.
Click to expand...

Dan,

Per Vans, I used 0.125 2024 T3. Good eye, there is an additional 0.63 spacer in there as well. I did raise the rear spar to compensate and allow for the extra thickness of the gussets. So, without the shims the HS is located per plans.

The shims were added per the testing done by Bob Axiom and other RV-6 builders that found an .063 spacer trimmed the HS out a little better. It has been a couple years, so I would have to go back to my log to verify all this, but that is what I recall.
 
Vic,

It would be awesome if you could do that talk again and record it. I think most people who build a plane are trying to be as careful as they can be, they just don't know what they don't know.
It would also be really good to review AC 43.13 in some form of video series that beginners could watch. Maybe a Kitplanes series of articles? Even just reviewing what's in there so a builder would be aware that those standards exists and they could look up the details.
I believe just putting that information out there in a more accessible form would result in better built and safer airplanes.

Lenny
 
I did listen to Vic at Oshkosh and was well worth the time, and I appreciated his willingness to spend time doing so.

In addition as a builder, buyer, etc it would be great if we had a "common mistake" website or something to look at. For example if you were working on tail you could go to tail section and see the common mistakes people make, same for wings, wiring, engine, etc.

Seems would improve safety aspect.
 
Just out of curiosity and if it is not inappropriate to ask here, how much does a typical pre-buy inspection cost?
It maybe worth for a conscientious owner to purchase one of these, of course from a more reputable inspector like Vic, even if not selling and to put his/her mind at ease.
 
Bavafa said:
Just out of curiosity and if it is not inappropriate to ask here, how much does a typical pre-buy inspection cost?
It maybe worth for a conscientious owner to purchase one of these, of course from a more reputable inspector like Vic, even if not selling and to put his/her mind at ease.
Click to expand...

In other words....you are asking about a Condition Inspection.
 
The last 2 issues of Kitplanes had my articles on Prebuys. You might take a look at them. And of course call me if you need help. Facetime works really well these days to look at problem areas.

I will work on continuing to write about builder errors, both for KP and perhaps for a sticky here.

Vic
 
Sam Buchanan said:
In other words....you are asking about a Condition Inspection.
Click to expand...

I don't think so Sam...while the inspections may be very similar, the end result on a pre-buy makes no airworthiness determination in the eyes of the law.

I am no expert on this aspect of the FAR's and the A&P/A&P IA's on this site can elaborate further on this, particularly when dealing with E-AB aircraft.

But, I am pretty sure in the certified world, once an "annual" is commenced it continues until an airworthiness determination is made, or a "with discrepancies" exception is noted. Edited to add: I don't know, but assume this same process continues on conducting a Condition Inspection on an experimental aircraft as well.

Now in my case...I converted the "pre-buy" on my RV-7 into a condition inspection after I had enough info from the pre-buy (in progress) to make a decision to go forward with the purchase.

Sellers are cautioned about allowing a condition inspection (or annual) be conducted as a "pre-buy" because if as part of the inspection something is found that could affect airworthiness, the seller may have an un-flyable aircraft on his hands...vs...a pre-buy discovering the same thing (in the eyes of the law) hasn't the same ramifications. It just failed a pre-buy...not a condition inspection.

Mike Busch also put out a pretty good webinar on this as well...mainly involving the certified world, but still there were some very good areas to be aware of involving aircraft pre-purchase inspections regardless of certified/experimental.

Rob
 
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Aggie78 said:
I don't think so Sam...while the inspections may be very similar, the end result on a pre-buy makes no airworthiness determination in the eyes of the law.
Rob
Click to expand...

I tend to agree here, beside I really not sure what a pre buy covers so it might or might not be as complete as the annual. I was under the assumption (possibly incorrectly) that a pre-buy operates on the assumption that the AC is airworthy but checks on the quality of the work and some possible issues which does not negate the airworthiness of the plane.
 
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Ok, I have a question...

We just had a recent thread over in the RV-10 forum in which one guy was recommending recycled cotton fiber insulation in contact with the cabin side of a firewall. Another had filled the spaces below the floorboards with a highly flammable urethane foam. There are hundreds of airplanes out there flying around with polyester fiber or rubber "soundproofing" pads on firewalls. And recently, I saw an RV-7 fresh from a condition inspection with pink Dow foam board on the cabin side of the firewall.

These materials more or less guarantee a fire in the cockpit following an engine compartment fire....and it's not like it has never happened. Remember Vern Dallman?

http://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20001211X11589&ntsbno=LAX99LA063&akey=1

So why are they getting past pre-buys and condition inspections?
 
DanH said:
Ok, I have a question...

We just had a recent thread over in the RV-10 forum in which one guy was recommending recycled cotton fiber insulation in contact with the cabin side of a firewall. Another had filled the spaces below the floorboards with a highly flammable urethane foam.
http://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20001211X11589&ntsbno=LAX99LA063&akey=1

So why are they getting past pre-buys and condition inspections?
Click to expand...
Dan,
Do you recall any experience with these in your testing?

http://www.aircraftspruce.com/catalog/appages/dampingpanels.php?clickkey=269125

I remember I had a small piece left over which I put a torch to and it did ignite and burn but not sure if that is an appropriate test using a torch.
 
It's hard enough finding the right 8, but looking at these concerning pictures of less than quality build technics could lengthen my search but lengthen my life as well.....thanks for sharing Walt ;)
 
Lenny Iszak said:
It would also be really good to review AC 43.13 in some form of video series that beginners could watch. Maybe a Kitplanes series of articles? Even just reviewing what's in there so a builder would be aware that those standards exists and they could look up the details.

Lenny
Click to expand...

If you look at issues form the past year, you'll see a series titled "Best Practices" in the magazine - written by A&P/DAR Dave Prizio. The purpose of that series is exactly what you're proposing - to document the content of AC 43.13 in a modern format for today's kit builders. It doesn't appear every month, but it has no end in sight.....

Paul
 
Regarding a pre-buy vs. a Condition Inspection. Most of my prebuys are thorough enough that they could be signed off as a condition inspection. It's amazing how many things I find after the Condition Inspection was supposedly completed. Both the buyer and the seller end up winning, even if the potential buyer walks away, as the current owner knows what needs fixing on the airplane.

Vic
 
Ironflight said:
If you look at issues form the past year, you'll see a series titled "Best Practices" in the magazine - written by A&P/DAR Dave Prizio. The purpose of that series is exactly what you're proposing - to document the content of AC 43.13 in a modern format for today's kit builders. It doesn't appear every month, but it has no end in sight.....Paul
Click to expand...

Certainly best practices, although I dunno about AC43.13. Per the FAA office (AFS 300) responsible for it, AC43.13 is to be used only in the absence of direction from a manufacturer. And the book itself contains errors.

Check the title page:

This advisory circular (AC) contains methods, techniques, and practices acceptable to the Administrator for the inspection and repair of nonpressurized areas of civil aircraft, only when there are no manufacturer repair or maintenance instructions.

The legal basis is found in FAR 43.13(a), also quoted on the title page:

... each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer?s maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, or practices acceptable to the Administrator?.
 
I agree with you Dan - although we all tend to refer people to AC-43.13 as a reflex, the truth is, it's a great reference document of you're restoring a T-6 or B-17...that's sort of the age of many of the illustrations. Part of Dave's task with his series is to cover best practices from a modern perspective - in other words, when it comes to things like sealants, we DO have better alternatives to what they had in the 1940's.....
 
One of the difficulties for the working engineer is that in some instances the desired characteristic differs from AC-43.13. While the engineer can document the necessary information in the maintenance manual, the possibility is always there that someone in the field might simply revert to the information in AC-43.13. So is it better to design the part optimally or to design it to be maintained in a standard manner?

If you do make any modification such that the plans and manual no longer apply to a specific area, you ought to describe it in the maintenance manual that you're keeping as you build.

Dave
 
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Returning to the question at hand....

We split hairs over legal references, and discuss washer counts and exposed threads. We gnash teeth over edge distances, and condemn those who stray. An airplane flies 20 years with ugly rivets which do not smoke, but none the less, we point fingers and say "Look at that...what a fool!"

So why do experienced inspectors give a pass to plastic, rubber, and foam insulation additions that negate the fundamental purpose of a firewall?
 
Ugh...

So, I probably need to start another thread on pre-buys where we can see all of the problems. Here is just one of the things I found today on an RV-6 that we were promised was perfect.

It is a welded patch across the ball joint on the exhaust system! I noticed a broken adel clamp hangar and followed it up the exhaust pipe. Lot's of strain here.


Vic
 
DanH said:
So why do experienced inspectors give a pass to plastic, rubber, and foam insulation additions that negate the fundamental purpose of a firewall?
Click to expand...

First of all, point well taken, and I intend to follow your advice with respect to flammable materials on the firewall. That being said, the oversight and responsibility has to shift from the inspector to the builder/operator somewhere, no? As awful as they are, aircraft fires are pretty rare. Should we also have the inspector ruling out a builders choice of carpeting, or seat materials? What about pilot/passenger clothing? Right or wrong, the firewall seems to be both a physical and mental dividing line between hot parts and the area where creature comforts rule. Back side of the firewall, anything goes...

erich
 
As a DAR I don't really want to get into questioning "accoutrements" on the aft side of the firewall. There are so many improvements and new products these days that it is hard to keep up with all of it. To be fair, a good portion of the airplanes I inspect do not even have the interiors completed yet, so a lot of things can get put into the aircraft that I never even see at the initial Airworthiness Inspection. The same goes for anything on the airplane after we leave. It can all get changed without anyone really looking over it, other than a major modification, which even then doesn't necessarily require an inspection.

It's even amazing how many forget to do another W&B after paint and interior are added.

I do think some responsibility rests upon the shoulders of the builders to build a safe airplane.

Vic
 
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erich weaver said:
As awful as they are, aircraft fires are pretty rare.
Click to expand...

So are lost horizontal stabilizers.

vic syracuse said:
As a DAR I don't really want to get into questioning "accoutrements" on the aft side of the firewall.
Click to expand...

We're talking prebuy here, not initial airworthiness. A buyer, who is usually not a builder, brings a long-finished airplane to a highly respected guy for an opinion. Can the highly respected guy, who has not been hiding under a rock, shrug his shoulders and say "I don't know anything about that material"?

Remember, some of this stuff is pretty easy to identify. For example, if it's pink and has a cartoon panther on it, it's probably styrofoam.

http://www.foamular.com/foam/products/foamular-150.aspx
 
DanH said:
Certainly best practices, although I dunno about AC43.13. Per the FAA office (AFS 300) responsible for it, AC43.13 is to be used only in the absence of direction from a manufacturer. And the book itself contains errors.

Check the title page:

This advisory circular (AC) contains methods, techniques, and practices acceptable to the Administrator for the inspection and repair of nonpressurized areas of civil aircraft, only when there are no manufacturer repair or maintenance instructions.

The legal basis is found in FAR 43.13(a), also quoted on the title page:

... each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer?s maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, or practices acceptable to the Administrator?.
Click to expand...

Maybe I missed it, did Van's put out a Maintenance Manual or ICA while I wasn't looking?
 
ty1295 said:
I did listen to Vic at Oshkosh and was well worth the time, and I appreciated his willingness to spend time doing so.

In addition as a builder, buyer, etc it would be great if we had a "common mistake" website or something to look at. For example if you were working on tail you could go to tail section and see the common mistakes people make, same for wings, wiring, engine, etc.

Seems would improve safety aspect.
Click to expand...

I second the idea of a "Common problem" thread. I pulled the emp fairing yesterday to verify all my holes where where they belonged...😎
 
DanH said:
So are lost horizontal stabilizers.



We're talking prebuy here, not initial airworthiness. A buyer, who is usually not a builder, brings a long-finished airplane to a highly respected guy for an opinion. Can the highly respected guy, who has not been hiding under a rock, shrug his shoulders and say "I don't know anything about that material"?

Remember, some of this stuff is pretty easy to identify. For example, if it's pink and has a cartoon panther on it, it's probably styrofoam.

http://www.foamular.com/foam/products/foamular-150.aspx
Click to expand...

Dan, I agree with regarding giving opinion for a Pre-buy vs. an initial airworthiness inspection with regards to accouterments. I missed that part of the question.

Vic
 
vic syracuse said:
I only have the slide set currently. It did not get recorded at OSH.

Vic
Click to expand...

I bet you're audio from OSH got recorded. I'd be happy to sync the audio with your powerpoint slides if you're interested.

Let me know if that is something you want to pursue and I'll talk to the folks that did the audio recordings to see if we can get your session.

bob
 
rleffler said:
I bet you're audio from OSH got recorded. I'd be happy to sync the audio with your powerpoint slides if you're interested.

Let me know if that is something you want to pursue and I'll talk to the folks that did the audio recordings to see if we can get your session.

bob
Click to expand...

I didn't see any recording equipment there, Bob, but that sure would be great. You are welcome to check and I can certainly send you the presentation if you have a dropbox or something. It's too large to email.
Vic
 
Bavafa said:
http://www.aircraftspruce.com/catalog/appages/dampingpanels.php?clickkey=269125
Click to expand...

Mehrdad, I have not run any full scale tests with that particular material. However, your question is timely.

I remember I had a small piece left over which I put a torch to and it did ignite and burn but not sure if that is an appropriate test using a torch.
Click to expand...

So how can a builder, or an inspector doing a prebuy, easily judge the suitability of a material they find attached to the cabin side of a firewall?

Remove a small sample. Grab your little propane torch. Apply a flame to the sample for a few seconds, and observe. Here's the simple, practical rule:

If you can make a small flame with a small heat source, you will get a large flame with a large heat source. If you get a little smoke with a small heat source, you will get a lot of smoke with a large heat source.

So how much is too much? You're looking for zero. At first that may seem like an excessive standard, but ask yourself how much open flame you want in the cockpit at 1000 feet, or 10,000. How much smoke, and if you ventilate, will you make the fire worse?

Any material marked "flame retardant", "flame resistant", "Meets FAR 25.853", or similar is suitable for cabin sidewalls, floors, and ceilings at some distance from the firewall, but they are not suitable for contact with the firewall. Almost without exception, they will smoke and burn, some with significant ferocity, as long as they are in contact with the heat source. You have no control of the heat source in the case of an engine compartment fire. You can't just turn it off, or change its size.

You may be surprised to find that 25.853 materials are legal when placed in contact with a certified GA firewall. The actual reference is 23.853(f). It's why advertisers can use the phrase "suitable for firewall" in literature and catalog listings. 23.853(f) runs entirely counter to another very sensible section, 23.1182. Go ahead, read 'em both.

Practically anything is legal with an EAB. In the EAB world we deal with practical reality. Let's try a thought exercise.

Should (or would ) a DAR approve an EAB with a sheet aluminum firewall? Would an A&P sign off a condition inspection if he found an aluminum firewall? What opinion would an inspector offer his client if he found an aluminum firewall during a prebuy?
 
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DanH said:
Remove a small sample. Grab your little propane torch. Apply a flame to the sample for a few seconds, and observe. Here's the simple, practical rule:
Click to expand...
Dan,
I appreciate your feedback, it follows logic and I ought to do more testing as I have put some of these material on the cool side of my FW, partly based on the description which state
"It is an excellent insulator for conducted heat and is an excellent heat reflector. Fireresistant and self-extinguishing per FAA test procedure"

Perhaps a more realistic test would be to attach some of these material to a piece of stainless steel sheet and then apply the torch.
 
Bavafa said:
...I ought to do more testing as I have put some of these material on the cool side of my FW, partly based on the description which state "It is an excellent insulator for conducted heat and is an excellent heat reflector. Fireresistant and self-extinguishing per FAA test procedure"
Click to expand...

You've already done all the testing you need; it burns when you apply a torch. A larger heat source will just result in a larger fire. Do yourself a favor; remove it, along with all traces of the self-stick adhesive.

BTW, the above catalog description isn't a lie. It says "fire resistant" and the data sheet does in fact reference 25.853. Again, fire resistant is not fireproof, and 25.853 materials burn merrily when kept in contact with the heat source.

However, the last sentence in the Aircraft Spruce text ("Apply to firewall, fuselage - anywhere a vibration problem exists") is apparently the invention of their copywriter. The linked 3M product document makes no firewall claim:

http://www.aircraftspruce.com/catalog/pdf/tds4014.pdf
 
DanH said:
However, the last sentence in the Aircraft Spruce text ("Apply to firewall, fuselage - anywhere a vibration problem exists") is apparently the invention of their copywriter. The linked 3M product document makes no firewall claim:

http://www.aircraftspruce.com/catalog/pdf/tds4014.pdf
Click to expand...
This however present another problem, at what point do we take their word for it and how practical would it be if we were to check and validate every description/claim of the given item. If I buy some 6061, would I need to test to make sure it does meet the standard that has been claimed for that piece of aluminum?!??!

Back to the fire hazard issue, I have used some FIBERFRAX on my cowl with very good results in regards to heat resistance. I will run some test with the torch to see how it will do and if better, replace my FW insulation with FIBERFRAX.
 
Bavafa said:
...at what point do we take their word for it...
Click to expand...

They linked the 3M document. Even if they didn't, it is still the builder's responsibility to do the homework before choosing a material.

I will run some test with the torch to see how it will do and if better, replace my FW insulation with FIBERFRAX.
Click to expand...

Not suitable for the cabin side. The binder (glue which holds the individual fibers together in the form of felt) will burn.

jthocker said:
Wow! Can you say thread drift!
Click to expand...

Thanks for joining us Jon. You're right; let's return to inspection. You're a well-respected fellow. Do you take a hard look at "firewall insulation" when you do a prebuy?
 
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jthocker said:
Wow! Can you say thread drift!
Click to expand...
I thought the purpose of this thread is to learn about potential issues and pre-buy inspections. I sure have learned from my discussion with Dan

Thank you Dan for providing invaluable feedback.
 
Yes, the thread drift is not what I intended. Let's try to stick to checking the various construction errors and not so much a discussion of "accessories."

Dan does raise some good discussion topics. I think another thread is warranted. But I do agree with the post regarding not having DAR's making those decisions. :)

As I have stated many times on this forum, I view my responsibility during the initial Airworthiness Inspection as an extremely through preflight. After I leave the airplane should be ready for that first flight after all of the cowlings and fairings get put back in. The chances of having a catastrophic failure should be very remote ( I am not saying never). I verify the aircraft is assembled properly, the controls work properly, and the engine has been run with the fuel flow tested.

With first flights taking place directly over the airport, an emergency landing if needed should be able to happen in very short order, and under control. One of the best advances to help make this happen is the Additional Pilot Program. Don't hesitate to use it! :)

Vic
 
Chris,
From what I am reading from this discussion, talking about the DAR inspection is not necessarily the point that I sense Dan is making. True the firewall insulation material could be an issue evaluated at that point. However, I was taking from Dan's comments the notion that he was concerned about knowledgeable inspectors who were evaluating airplanes for a pre-buy and/or conditional inspections not catching bad insulation materials when evaluating an airplane in a resale situation or one in which the pilot is not the builder. In this scenario the inspector is providing a conditional inspection for said non-builder.
 
RVbySDI said:
Chris,
From what I am reading from this discussion, talking about the DAR inspection is not necessarily the point that I sense Dan is making. True the firewall insulation material could be an issue evaluated at that point. However, I was taking from Dan's comments the notion that he was concerned about knowledgeable inspectors who were evaluating airplanes for a pre-buy and/or conditional inspections not catching bad insulation materials when evaluating an airplane in a resale situation or one in which the pilot is not the builder. In this scenario the inspector is providing a conditional inspection for said non-builder.
Click to expand...

Yes I accidentally deleted my post, but I agree that people doing pre-buys should bring up these types of issues and educate the buyer and builder. My concern was making this the job of DAR's, which I don't believe it is.

Vic did what I thought was an excellent airworthiness inspection for me - he checked all the critical areas, and also offered a few suggestions as well to improve things, all of which were appreciated.

Chris
 
vic syracuse said:
Let's try to stick to checking the various construction errors and not so much a discussion of "accessories."
Click to expand...

Come on Vic, we're not talking about a bad radio. We are talking about a construction error, the kind that has resulted in death, so humor me, and answer this question, please.

You're doing a prebuy, the subject of this thread. Do you include a close look at the material on the cabin side of the firewall?
 
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Pre buys

Dan,

I don't advertise that I do pre buys( I think)! After doing 3, for friends, and then finding serious deficiencies in each case, I believe I will stop, especially if I have to worry about firewall insulation!😱
 
Some off-line insulation discussions suggest the key issue is awareness.

A DAR can be unhappy with an insulation choice, but may have serious difficulty denying an airworthiness certificate on an authority basis. I say "may", because they don't all report to the same FSDO supervisor, and well, we all know how that can be. There is no common knowledge to back him up.

An A&P doing a condition inspection has a similar problem, and to be practical, he also has a business problem. The A&P who wants a bad insulation choice removed can rapidly find himself alone. Plenty of other A&P's will sign it off.

Condition inspections are a little easier in one respect; buyers hire an inspector for an opinion, and in general, they value that inspector's opinion or they would not have hired him. However, it's not universal; plenty of prebuys get hired without a personal relationship. There is also a seller problem. The seller is often the builder, and he thinks his insulation approach was safe, and his mechanic never said anything about it, so why is the prebuy guy making a big deal out of it?

Now consider: None of these inspectors would have a problem if awareness was as universal as the need for edge distance, or the problems with old slosh compound in fuel tanks.

Yeah, we need to work on awareness.

How bad is the actual problem? Take the time to read through the very recent thread linked below.

http://www.vansairforce.com/community/showthread.php?t=141016

Research is not hard. Most products have technical bulletins, if folks will just read them. Most don't, and if they do, they don't bother to research the referenced test standards. Actually, it often not even that hard. Following a few links found a YouTube video of an RV-10 builder spraying the enclosed spaces under the forward floors entirely full of a urethane foam product...the same product another YouTube video demonstrates to be highly flammable. Apparently the builder's investigation of the product's suitability seems to have been reading the word "fire" on the front of the can.

It's a construction error. And it's dangerous. Let's stop it.

I'll start a new thread in the not distant future. Having raised some awareness, let's return this thread to tail attachment.
 
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Questionable attachment

Thanks to this thread I made sure to check this area on a project airplane I looked at today. Here are some pics. This makes me wonder about all the critical areas that cant be seen.








 
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I went with 1"x1" angle on my RV-4 project to prevent the bolt edge distance issues. Plus I was very very careful when drilling those holes. The 3/4" angle gives you zero room for error
 
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