strut attachment AD - failed

Re: strut attachment AD - failed

Before you repair your strut fitting, compare the cost difference between that and installing new fittings. Then compare what the little guy on your shoulder is going to be whispering in your ear the next time you take off in that airplane.

I suspect that with a brand new fitting installed by a fully competent welder, the little guy on your shoulder is going to be whispering something like, "You are a safe pilot, you are a tribute to general aviation, I bet your wife is glad you erred on the safe side".

After even the very best repair I suspect the little guy on your shoulder will be whispering something like, "Gee, I hope that repair is as strong as a new fitting, that weld looked pretty good....didn't it?, so what if the repair fails-you saved almost a grand.

There is nothing like peace of mind for an enjoyable flight!

***************************

papi kak

[Pearson]

Re: strut attachment AD - failed

Before you repair your strut fitting, compare the cost difference between that and installing new fittings. Then compare what the little guy on your shoulder is going to be whispering in your ear the next time you take off in that airplane.

I suspect that with a brand new fitting installed by a fully competent welder, the little guy on your shoulder is going to be whispering something like, "You are a safe pilot, you are a tribute to general aviation, I bet your wife is glad you erred on the safe side".

After even the very best repair I suspect the little guy on your shoulder will be whispering something like, "Gee, I hope that repair is as strong as a new fitting, that weld looked pretty good....didn't it?, so what if the repair fails-you saved almost a grand.

There is nothing like peace of mind for an enjoyable flight!

Re: strut attachment AD - failed

Since Maule makes ceconite covered planes I would think this tool works on ceconite.

Also the instructions make no mention of using it on any particular fabric it just says fabric.

I also suspect that the type of fabric makes no difference.

Looks to me like it is simply applying force on a known shape against a thin sheet as a means of estimating the sheet's ability to withstand tension so it's function is pretty independent of the fabric type.

I am sending mine in for calibration and will ask about this subject at that time.

Looks like I was wrong about this part in red.

Here is the paragraph from AC43.13-1b

2-34. FABRIC TESTING. Mechanical devices
used to test fabric by pressing against or
piercing the finished fabric are not FAA approved
and are used at the discretion of the
mechanic to base an opinion on the general
fabric condition. Punch test accuracy will depend
on the individual device calibration, total
coating thickness, brittleness, and types of
coatings and fabric. Mechanical devices are
not applicable to glass fiber fabric that will
easily shear and indicate a very low reading
regardless of the true breaking strength. If the
fabric tests in the lower breaking strength
range with the mechanical punch tester or if
the overall fabric cover conditions are poor,
then more accurate field tests may be made.
Cut a 1-1/4-inch wide by 4-inch long sample
from a top exposed surface, remove all coatings
and ravel the edges to a 1-inch width.
Clamp each end between suitable clamps with
one clamp anchored to a support structure
while a load is applied (see table 2-1) by adding
sand in a suitable container suspended a
few inches above the floor. If the breaking
strength is still in question, a sample should be
sent to a qualified testing laboratory and
breaking strength tests made in accordance
with American Society of Testing Materials
(ASTM) publication D5035.

Re: strut attachment AD - failed

My understanding is that the "Maule" tester is the unofficial name for the Betts tester ("Bettsometer") (named after the designer) and that the results have no standing for certified aeroplanes, since it was designed for uncertified ultralights.

But I am willing to be corrected.

Rob

You are exactly correct. Maule states that too. ie that it is unofficial (it is pre -ultralight so must not be a bettsometer)

But it better than a thumb, pencil... or nothing

Its merely a guide

[Robert Lees]

Re: strut attachment AD - failed

My understanding is that the "Maule" tester is the unofficial name for the Betts tester ("Bettsometer") (named after the designer) and that the results have no standing for certified aeroplanes, since it was designed for uncertified ultralights.

But I am willing to be corrected.

Rob

Re: strut attachment AD - failed

DJ,

I am a seaplane operating from brackish water.

Over the years, the bracket and surrounding areas had been painted, painted, painted, sprayed with goop, all in an effort to protect the area from corrosion. There was so much stuff, you really couldn't inspect the area to comply with the SB.

We cut away the fabric and sandblasted the area to bare metal using an inexpensive blaster hooked to a small shop (Sears) compressor. The sand gets into ALL the nooks and crannies.

I guess I'm glad the AD forced me and the A+P to really clean up and check this area out. We had the area x-rayed as well just for peace of mind.

This is an inexpensive way to clean your bracket area and have the welding repair done without spending a fortune to completely rebuild the plane.

I have done that also maybe 20 years ago and afterwards the grit from blast ruined the cables at the fairleads. Might want to take a look just in case.

Re: strut attachment AD - failed

thanks Dave. do you have it in electronic format? .pdf maybe?
Also, can someone tell me how these fittings are attached to the plane? welded? or what? how would one replace the fitting?

Will have to copy and send or FAX to you.

They are welded on, but the 337 I will send does not replace it per se. It wraps a new piece arround it and welds the new piece to the old one and the fuselage.

So you end up with new fitting wrapped over top of the old one.

Re: strut attachment AD - failed

Since Maule makes ceconite covered planes I would think this tool works on ceconite.

Also the instructions make no mention of using it on any particular fabric it just says fabric.

I also suspect that the type of fabric makes no difference.

Looks to me like it is simply applying force on a known shape against a thin sheet as a means of estimating the sheet's ability to withstand tension so it's function is pretty independent of the fabric type.

I am sending mine in for calibration and will ask about this subject at that time.

[N74DV]

Re: strut attachment AD - failed

thanks Dave. do you have it in electronic format? .pdf maybe?

Also, can someone tell me how these fittings are attached to the plane? welded? or what? how would one replace the fitting?

Re: strut attachment AD - failed

I have a 337 for a previously done repair and attached to it is a template for cutting out a patch from 4130 plate.

Could send you a copy if it helps.

Dave

[N74DV]

Re: strut attachment AD - failed

I think the Maule tester is for organic fiber covering isn't it?? He told me he tested up to 47lb and did not punch through.

The fabric was done in 1971 but it was kept in a garage for about 35 years. Only been outdoors for about 3 years.

[Marv]

Re: strut attachment AD - failed

Keven i may be wrong, but i think you have it backwards. The maule tester was made for cotton and Irish linen, and there is no maule test for ceconite. Marv

[crispy critter]

Re: strut attachment AD - failed

thanks for all the great info guys. You're giving me some excellent feedback. I'm going to the shop on Monday morning to meet with the A&P. I'm going to print out this thread and carry along with me.

With some luck I may be able to get flying again cheaper and sooner that I had thought.

One positive note was he tested the fabric again while he looked at the fittings. I still have Irish Linen on the plane so he used a Maule tester. Said the punch test passed no problem. So looks like I can still go another year or more before a recover.

Do you know how hard he punched the fabric? The maule tester is a dull point tool that is like a spring slide,the harder you push the more pounds of pressure the tool reads. I just wonder after 30 years(I believe that's what you said)how much pressure he punched it up too. On ceconite airplanes(which is what the tester was made to test) 30-35lbs is normally what most flunk it at.....I can't imagine 30 year old cotton punching 30lbs and holding....nothing for you to worry about but I was just curious for my own wondering mind.

[N74DV]

Re: strut attachment AD - failed

thanks for all the great info guys. You're giving me some excellent feedback. I'm going to the shop on Monday morning to meet with the A&P. I'm going to print out this thread and carry along with me.

With some luck I may be able to get flying again cheaper and sooner that I had thought.

One positive note was he tested the fabric again while he looked at the fittings. I still have Irish Linen on the plane so he used a Maule tester. Said the punch test passed no problem. So looks like I can still go another year or more before a recover.

[jdoran]

Re: strut attachment AD - failed

DJ,

I am a seaplane operating from brackish water.

Over the years, the bracket and surrounding areas had been painted, painted, painted, sprayed with goop, all in an effort to protect the area from corrosion. There was so much stuff, you really couldn't inspect the area to comply with the SB.

We cut away the fabric and sandblasted the area to bare metal using an inexpensive blaster hooked to a small shop (Sears) compressor. The sand gets into ALL the nooks and crannies.

I guess I'm glad the AD forced me and the A+P to really clean up and check this area out. We had the area x-rayed as well just for peace of mind.

This is an inexpensive way to clean your bracket area and have the welding repair done without spending a fortune to completely rebuild the plane.