!)$(^@ FAA SOB's Trying to Shut My 337 down!

[VictorBravo]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

The 5 minute epoxy I used (actually 15 minute epoxy) was tested to an ASTM standard, having well over 1500 PSI in a "lap shear" strength test. I figure that if you only achieved one THIRD of that strength in actual shop practice, the glue is still good for 500+ pounds.

The screws will pull out of those wooden blocks LONG before this epoxy fails in shear. One of the engineers I spoke with briefly said that this was the part about my installation he did not like, because over time the screws want to pull out of the wood. True enough, but there has to be a load on the screws to make that appen.

My rough calculations show that there is very little load on the screws, something like 15 pounds each or less.

I am aware of at lest one aircraft and probably several others, that were certified by a governmental agency as airworthy, that used wood screws to hold windows into wooden frames. The British Auster that I owned had a million little brass wood screws holding some of the windows in. I suspect many other pre-WW2 airplanes used brass wood screws to hold a lot of secondary structure together.

[Ragwing nut]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

Some one metioned owner Maintinence, Would be idel for simple aircrafts.
Material standards are another thing. Bill's example with 5 miniute epoxy is a good one. Does fine minutet epoxy meet a industrial standrad?
The new Light sport category uses ASTM for material standard.
What it means in practical use of nut and bolts, glues etc I don't know. Anything what meets a standard has to be tested, it is when becomes a known entiety, with known properties.
Therefor I can use it in a design and say if you use this you are ok.
AN standards has been the best for many years, but as I worked in the autoindustry and maintined high tech machinery I seen many things I would use in an aircraft as it is better, (in my judgement,) when AN standard.
We also have to keep in mind what an aircraft is desinged to be flexiable and
in the case of bolts, the AN bolt maybe better at 125 000 psi strengeth when a 160 000 Psi bolt what is not as resistance to chock waves etc becuase it is harder.
I do think someone (EAA AOPA)has to sitt down with FAA / DOT and look at the standards used in the past and compare with the new standards. It would be simlar to what was dune with Auto fuel STC.
Lots of development has happened in the last 40 years, EAA Canada COPA and RAA here in Canada got through the owner maininece, but we can not leave the country, if we are in what category.
FAA s rep shot it down in the negotioations in Ottawa.
In USA you have to have a AI doing the annual on a homebuilt, if you are not the builder.
The repirmans certifact would take care of what.
If you try to make a living in the GA it would be a heavy competion to the aircraft mechanics proffesion.
Taylorcraft owners should maybe concider the light sport category if possible.
Len

You still have to meet Part 43 standards or manufacturers repair standards. Owner maintenance doesn't mean you can do what you want not even under experimental regulations. you only have to be an A&P for experimental inspections.

Mike

[Ragwing nut]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

The 5 minute epoxy I used (actually 15 minute epoxy) was tested to an ASTM standard, having well over 1500 PSI in a "lap shear" strength test. I figure that if you only achieved one THIRD of that strength in actual shop practice, the glue is still good for 500+ pounds.

The screws will pull out of those wooden blocks LONG before this epoxy fails in shear. One of the engineers I spoke with briefly said that this was the part about my installation he did not like, because over time the screws want to pull out of the wood. True enough, but there has to be a load on the screws to make that appen.

My rough calculations show that there is very little load on the screws, something like 15 pounds each or less.

I am aware of at lest one aircraft and probably several others, that were certified by a governmental agency as airworthy, that used wood screws to hold windows into wooden frames. The British Auster that I owned had a million little brass wood screws holding some of the windows in. I suspect many other pre-WW2 airplanes used brass wood screws to hold a lot of secondary structure together.

What is the engineer's background? I get tired of Boeing 737 DER's trying to tell me how I am suppose to build a Cub when they have never operated, maintained, or flown one. Find another DER if possible, or send the 337 to another FSDO.

mike

[Forrest Barber]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

In USA you have to have a AI doing the annual on a homebuilt, if you are not the builder.
I hope that has NOT been changed, to my knowledge an A&P can do the "Condition Inspection" there is no "Annual" on the Exp. Homebuilt...

[Ragwing nut]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

In USA you have to have a AI doing the annual on a homebuilt, if you are not the builder.
I hope that has NOT been changed, to my knowledge an A&P can do the "Condition Inspection" there is no "Annual" on the Exp. Homebuilt...

As far as I know there is no annual for experimentals, only conditional inspections. I may be wrong, and have been before. I guess I need to get the book out again and verify.

Mike

[Richard Boyer]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

Yeah, I think it is book time. I thought that experimentals DID require an annual but there were a couple of outs. If you have the repairmans certificate for that particular airplane, then you are allowed to do the annual. If you don't have the repairmans certificate then all it requires is the signoff from an A&P not an IA.

[VictorBravo]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

What is the engineer's background? I get tired of Boeing 737 DER's trying to tell me how I am suppose to build a Cub

I completely understand what Mike is saying, and have met "engineers" who I woudn't let pick up a wrench.

I do not know the full background of the engineer who brought the wood screws into question. It was a valid question that I just happen to not fully agreee with his answer.

However I do know the background of the engineer who has been "looking over my shoulder" and has consulted with me on many things like this, back from my F-1 racing days. THIS fellow is as good as it gets... he is a graduate of the old "apprenticeship" system at DeHavilland in England, where they started by sweeping the floors and all that.

He was famous for walking into JPL or Rocketdyne with a slide rule in a wooden case and using it to troubleshoot problems that the younger engineers could not solve. He understands structures very very well, and is the "engineer emeritus" of the Formula One racing group. Fortunately he can adapt to the requirements of little airplanes and big airplanes. He is not a DER unfortunately.

[Richard Boyer]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

VB,

I just finished putting a whole MESS of panels in on the bottom of my WOOD WING mooney. The majority of them screw into......gasp.....wood. Vne is 183 (supposedly) and they all managed to stay in since 1957. So, I am thinking that the FAA dude needs to rethink his thinkin'.

[VictorBravo]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

You still have to meet Part 43 standards or manufacturers repair standards.

Rant Alert! Rant Alert!

Mike's absolutely right, which is why I started researching the glue issue. The FAA inspector called the glue into question because it was not known to him as an FAA approved glue. So I looked up the glue requirements in Part 43 and the old CAR 4.

Part 43 stated that the glue is OK if it meets a Mil-Spec (or the airplane manufacturer's approval, or a previously published aircraft glue spec).

So I started looking at Mil-Specs for glue and found that the military now uses ASTM industrial specs in place of the older obsolete "retired" mil-specs.

I actually contacted ASTM by e-mail and got a response from them that the particular ASTM test number I was referring to is now the de facto Mil-Spec for room temperature general purpose epoxy because that is what the military uses, rather than keeping a huge library of 60 year old specs.

THEN, I looked up the old obsolete Mil-Spec for Resorcinol (which is universally accepted by the FAA for most aircraft wood glue applications) and looked at the minimum test shear strength requirement.

It turns out that the epoxy I used was ASTM tested to 1900 PSI in lap shear, and the minimum acceptable shear strength for Resorcinol was something like 350 or 400.

So I figured that I had proven not only that the epoxy was legal for Part 43 (because it meets a Mil-Spec which is in fact the equivalent ATSM now), but it is also about 4 times stronger than the resorcinol.

Along the way, I actually got scientific reports from the USDA Forest Products Research Lab in Wisconsin (who develpoped the original aircraft glues in the 1920's), looked up all sorts of WW2 vintage Mil-Specs, AN specs, and looked at all the ASTM epoxy tests that I could find. It was quite a ride

(NOTE: if there were any significant PEEL loads on the glue joint, there is a legitimate concern about how a thicker epoxy like this would perform. But this is not the type of loads on this glue joint and the loads are very low. But for the record, you can't just assume that any epoxy is stronger than resorcinol and build an airplane with it rergardless of what type of loads are present!!!)

When I presented the documentation of this whole glue research episode to the FAA, I think they felt that I had "bludgeoned" them. They apparently got pissed off one one level or another and just closed the door on me.

Although I certainly do not expect my skylight glue joints to fall apart, if I were doing it all over again I would use a glue that could not be called into question. Resorcinol is a great glue but requires more precise glue joints and clamping practices in order to achieve it's full strength. There's an epoxy called FPL-16a (named for Forest Products Lab) that I believe is approved. West Systems epoxy with cotton flock would work great and I believe it is "previously approved" on some aircraft.

[VictorBravo]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

VB,

I just finished putting a whole MESS of panels in on the bottom of my WOOD WING mooney. The majority of them screw into......gasp.....wood. Vne is 183 (supposedly) and they all managed to stay in since 1957. So, I am thinking that the FAA dude needs to rethink his thinkin'.

Would you be kind enough to give me some more information on that Which panels, what the types of wood are, where the panels are put in, whether they are in the prop arc, what type of screws, etc? That would be VERY helpful to me... I am going to enjoy showing this info to a particular DER Please (please!) send this info to me... victorbravo (at) sbcglobal (dot) net

Thanks!

[Ragwing nut]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

There USE to be a process by which you could self certify glue using the boil method. Unfortunately that is where epoxy is weak is in heat. I have no bones about using epoxies in non-structural applications and use West Systems which has been approved by Waco Classic and other have had sucess getting approved as well due to Waco Classic.

Mike

[Ragwing nut]

Re: !)$(^@ FAA SOB's Trying to Shut My 337 down!

Would you be kind enough to give me some more information on that Which panels, what the types of wood are, where the panels are put in, whether they are in the prop arc, what type of screws, etc? That would be VERY helpful to me... I am going to enjoy showing this info to a particular DER Please (please!) send this info to me... victorbravo (at) sbcglobal (dot) net

Thanks!

Wing tank covers on Bellanca Cruisairs and Vikings are installed with wood screws. What do you install screws into when the entire airplane is made out of wood like a Mooney Mite, Culver Cadet, Johnson Rocket? Thin air? Idiots I tell you. I have no patience for people in authority that have no clue as to what they are talking about, especially the FAA.

Mike

[astjp2]

Sorry in advance for the rant! I'm pissed!

After jumping through a dozen hoops and being led to believe that they were imminently going to approve my Field Approval for the no-weld skylight, the FSDO informed me today that their office will not be processing my 337, and to have my IA submit it through another FSDO.

This is after they had me make several changes to the paperwork, several changes to the physical installation, and two FAA inspector visits.

The incident on the last visit, when I truly expected his blue stamp to come out and walk away with an approved 337, was the kicker. I was honest on all my paperwork, and called out the 5 Minute Epoxy glue by name which I used to glue a dozen little 1x2 wood blocks in place. I knew the epoxy was 100 times stronger than it needed to be for that application.

After his having seen that material called out since day 1 on my paperwork, he brought it into question at the last visit, saying that it was not an approved glue. I told him it was quite a little better than the HORSE HOOF glue (Casein) that was approved. He agreed that the epoxy was better physically, but that he would have a tough time in front of an NTSB judge explaining why the FAA signed off model airplane glue on a certified airplane.

So we talked for a while and he finally backed off enough to give me the option of showing that this glue was indeed an approved glue or met the standards for an approved glue. Then, he said, he would keep working with me toward the approval of this installation... fair enough.

So I spent the entire weekend researching the old Mil-Specs for several aircraft glues, the AC 43.13, the CAM 18, the CAR4 certifications, the ASTM test certifications, etc. etc. etc. After a brief struggle with the computer and the telephone, I found exactly what I was looking for: three different trails of information showing that 5 Minute epoxy met ( and greatly exceeded) the minimum Mil-Spec strengths for FAA approved Resorcinol, Formaldehyde glues, and the ASTM D 1002 tests which the DoD uses to replace the retired and obsolete epoxy Mil-Spec testing.

So I quoted the new 43.13 which says clearly that any airplane glue that meets a Mil-Spec or Aerospace Mat'l Standard for airplane wood glue is acceptable to the Administrator. I furnished the FAA with the minimum shear strength set forth in the Mil-Specs for Resorcinol and Formaldehyde glues (less than 500 psi lap shear), and the ASTM test results of 5 Minute Epoxy at 1900 psi lap shear. A similar Mil-Spec set forth a minimum shear strength of 1500 psi for epoxy.

Of course the epoxy has greater strength than the FAA approved wood itself, so an epoxy bond greater than 900 psi (ANC-18 shear strength of Sitka Spruce wood) is academic from a flight safety standpoint. Of interest is the old ANC-18 Army aircraft wood spec says that a glue joint must meet 1/2 or less of the wood material shear strength, meaning 450 psi for Sitka. This is acceptable to the FAA... 450 psi... and good old 5 Minute epoxy is 4 times stronger.

I submitted irrefutable and valid documentation that showed this epoxy would meet or exceed the requirements set forth in 43.13. I e-mailed him all the info, mil-spec and other related internet resources to verify at his discretion, etc.

Today I get a call from the FAA inspector saying that they just don't want to deal with it, more or less, hanging their hat on the idea that my IA is based in Las Vegas so the local FSDO won't accept it... except for the fact that this geographical issue had been solved early on, with specific approval my my IA's local FSDO to run this through the local FSDO here because the plane was here.

So i will have to resubmit the paperwork all over again through another FSDO, running the risk that they too will find an excuse to not deal with this.

Did I mention that there are NO changes to the primary structure in this 337, and the "form fit and function" of my skiylight corresponds almost exactly to the Taylorcrat F-21B series skylight which was a factory option?

You know, I was just starting to get a good feeling from the FAA, that maybe there are still some people in the organization that care about helping aviation! The FSDO inspector had flown Taylorcrafts, agreed 100% that the skylight was a worthwhile mod, and agreed 100% that my installation was well thought out, clean and safe in his opinion.

More than one person at my local airport has told me that this is a sleazy tactic the FAA uses on purpose, to sucker you in and create the illusion they are trying to actually help the little guy, when their real intention is to eventually squash the project or bury it in busy work so they don't have to sign anything off. I would have doubted this, except for the fact that one of my hangar neighbors had exactly the same experience... the same "bait and switich" right down to the details and the "I'm going to try and help you because I think this is a worthwhile mod"... from another FAA inspector on a PA24 Comanche instrument panel mod he was doing.

I'm completely disgusted with this episode and damn well pissed off at not being able to finish my annual and start flying. The EAA and AOPA have said there are good people in the FAA who really do care and they are working with those organizations to make it easier... but my personal experience with the FAA on this skylight project has been a nightmare and a wrongful nightmare at that. If there was ANYTHING unsafe or inappropriate on my installation, then that's one thing. But trying to discourage me, and then bury me in busy work until I got tired of fighting, then slamming the door in my face when I jumped through the last hoop, has cost the FAA my respect until further notice.

It is with great sadness and disappointment that I lose faith in the FAA's small airplane division, and must return to the old-school view of "it's us versus them".

Bill Berle

Bill I know that this is an old thread, did you ever get it approved?

[PA1195]

Better yet what's the N-Number? One of his Taylorcrafts the last in his list lives locally.

Gary