Borescope and fabric removal

[mhorowit]

In a previous thread we discussed the lifespan of fabric; I think we decided that although the fabric and covering may be fine after 20-30 years, it is a good idea to remove the fabric and inspect all within. That seems to be an expensive approach if the fabric doesn't by itself warrant removal.

Is there any place (that you would inspect with the fabric off) that cannot be examined with the fabric on and a borescope in hand?

Happy Holidays to all - Mike

[Robert Lees]

Re: Borescope and fabric removal

Very briefly, Mike:
Wings: the tops of the spars under the varnish just outboard of the strut fittings (for compression failures);
the root edge of the rear spar where fuel leaks rot the wood.

Fuselage: the lower longerons & sternpost.

Anyone else add any others?

p.s. Post PC Christmas, can we actually say "Happy New Year" instead of all this "Holidays" stuff?

[Don Eide]

Re: Borescope and fabric removal

Mike,

Yes. Every spot that the fabric is glued to, like the bottom of the
longerons. Thats where they rust out. Do you know who recovered it last?
Did they repair all the rusted and corroded areas?

I can only tell you what I have found on my last two rebuild projects.
1. A Piper L-4. I know, wrong brand.
It was recovered 6 years before we started to rebuild it.
The covering material was great. The job they did was poor.
We tore the fabric off and had a major rebuild ahead of us.
We replaced 6' of both bottom longerons and all cross members
from the tail post to the baggage compartment and a couple
of diagonal tubes. A new bird cage. A serviceable engine mount,
otherwise everything in front of the firewall is new. A new firewall/bootcowl.
New instrument panel. Overhauled all the instruments. All new glass.
All new interior. New tail wheel spring. New tailwheel. Total rebuild
of one elevator and rudder. Replaced the other elevator and both
Stabs. New spars, new wing tips, a couple new ribs, repaired a few others,
new struts and all strut and wing attach fittings. New cables. New
landing gear. Total rebuild of both doors. Repaired one broken brake master cylinder.
Remember this airplane was recovered only 6 years before we started the rebuild.

OKAY. No. 2 Now I'm rebuilding a Taylorcraft. I bought it from a guy who was going to do a little repair and paint and fly it.
The wings and ailerons were recovered in 1971. The fuselage and tail was recovered in 1977. I bought it in 1997 and started the rebuild before I got into the L-4.
So far I have found the following.
Both elevators had ribs rusted off at the trailing edge. The bottom rib
in the rudder was rusted off at both ends. Only held in place by the rib stitching. Many bolts worn and or rusted 1/2 way thru. Ailerons.
Anyplace where steel and aluminum touched, there was corrosion.
One aileron spar (wood) was made out of three pieces glued together.
All the glue was gone and the aileron hinge brackets were the only thing holding the spar together. The steel wing tip bow was rusted out and not attached at the rear. Pitted and rusted wing attach fittings. Doors totally
corroded out. I've got some serviceable ones. Brakes inop. Instruments
don't look good, will be overhauled.

And you want to fly it after 20 years???????????????????????? Not me.

Don

[Forrest Barber]

Re: Borescope and fabric removal

Amen to all that , I have found elevators rusted at rear so bad that I broke them with my hands. Struts too, Maule tester was not necessary I crushed the strut from the bottom with my thumbs, we had that section here for many fly-ins...Gosh this will be the 33rd year, where has the time gone? Sure you could trick up a borescope and other things but fabric removal is the best way!

[N96337]

Re: Borescope and fabric removal

I echo the posts above... my Bellanca had small pin sized spots of rust in the lower longerons.. move away 1/4 inch and the metal was fine... but both longerons got replaced all the way to the front! I've always said that the new fabrics are both good and bad...good in the fact that they last a long time, but bad in the fact that they last a long time.. hahaha. Like was said earlier, anywhere the fabric touches metal, or 2 dissimilar metals touch, you need to be looking at regularly! My spars were made in '46 and were glued up from lots of pieces and the good old casien (sp) glue had let go in a few joints and really couldn't be assesed properly with the fabric still in place. ONe of the really common problem spots with a Tcraft is the aileron hangers, where they attach the trailing edge cove.. alot of people compound an already big problem by using a stainless screw there, and in doing so, create a great little battery.
I've yet to see anything that had the fabric on that long that didn't have some place that needed some sort of attention.
John H.

[alwaysoar]

Re: Borescope and fabric removal

Who in their right mind would want to own one of these planes? (I'm not in my rilght mind, obviously!)

[flybikefarm]

Re: Borescope and fabric removal

I've owned my 46 t-craft N39972 for about a year and a half. It was recovered in 78 but never flown. It was in a barn with about twenty other old planes (the rest are all gone, don't ask). Most of the fabric came off on the ride home(trailer) it has been in my barn waiting to be rebuilt. This was a complete plane with only 743 hours total time no rust good wood and only a few small pieces missing. The fusalog is in the garage striped down waiting for primer. I am only the third or fourth owner of this plane. All the paper work is complete from test flight on 01/03/46 to present. This is my fourth rebiuld project, looks like it will be the easyest. The last three where all basket cases. George

[Sloanlow]

Re: Borescope and fabric removal

For the cost of an envelope set, I prefer to have a complete "look see" at the inside. If its that good then it deserves a new skin and paint.

My current experience is bad in that regard. Although my airframe is excellent and the recent mishap damage is slight, I have removed bad hardware from almost every system and assembly. Trash, excess paint, primer, glue, dirt, parts and the beginnings of corrosion. What appears to be airworthy is not airworthy at all in my mind. I like flying at night without worrying about things that I did not see during the annual. Don't get me wrong, I like my t-craft purchase and I am building it for me and mine and It will be right when I am finished. The cost of an envelop is nothing compared to what you get by recovering a plane. Make friends with someone who knows how to cover a plane, make a fun winter and spring out of it. Step outside your box and have fun doubling the value of your plane.

43011
Jim A.

[mhorowit]

Re: Borescope and fabric removal

For the cost of an envelope set, ....
43011
Jim A.

Jim - unless I attempt it myself (and I don't have an adequate place to do it) that cost to me is $10,000, not a trivial percentage of a $15,000 airplane - Mike

[mhorowit]

Re: Borescope and fabric removal

Let me see if I'm recapping this thread correctly.

What you folks are saying is there are places that CANNOT be checked during a pre-buy and CANNOT be checked during an annual and problems in these areas can have consequences which could dramatically affect flight characteristics, right?

If that's the case, how did you find an A&P to accept the liability and sign off your last annual? - Mike

[N96337]

Re: Borescope and fabric removal

That's one of the great joys of having an IA, Mike. Everytime something goes out the door, it's MY butt.... Back when I did alot of annuals, I once caught a neighbor taking his mags apart "to see how they worked" only 2 days after I'd signed off the annual... needless to say, I handed him a check for the exact amount he'd paid for the annual, grabbed the logs and ripped the page out that had my signature on it...
There are usually outward signs of a problem that one can see, but not always. As far as inspecting where fabric is glued on, it's mostly a "trust that it's ok" by looking at all the surrounding area, as well as a careful feel of the fabric glue joint to try to detect any small bumps or irregularities...but that's not always enough. I bought a Bellanca that had nice looking fabric, but old fabric (the guy said "she's ready to be assembled,have an engine installed and fly). The aircraft had been stored inside, but had signs of mice in it, so I decided to go ahead and redo the fabric. When I had it stripped, I was doing a real thorough inspection of the lower longerons, and found rust spots that were about the size of a pencil lead..as well as being just a bit "up" from the bottom of the tube (found out it was stored in a bit of a "roll" so the moisture didn't pool exactly on the bottom of the tube)... if you were 1/8" away, you wouldn't find them at that time... needless to say, I replaced them with new, but what I'm saying is that no matter how careful we are, sometimes we can't see everything. Had I not "lucked" on to one of those spots, I would've figured I had good tubes and not found out different until much later when the problem was much worse.
I've walked away from alot of annuals because the owner didn't want ALL of the inspection covers cut open on his airplane. We do the best we can, but we're not psychic...... It's also why liability insurance is waaaaay beyond reasonable...
John H.

[high time cub]

Re: Borescope and fabric removal

Who in their right mind would want to own one of these planes?

Perhaps someone that cut their teeth on a vintage British sports car.

[Yellow Duck]

Re: Borescope and fabric removal

Makes me want to pull mine apart after only 18 yrs. Always hangared,but always worring,being I didn't do the rebuild. It looks great, Buuuut ? Just wish it didn't take so long to do. Guess that is one reason I am looking for another aircraft. One to fly and one to rebuild.

[mhorowit]

Re: Borescope and fabric removal

Makes me want to pull mine apart after only 18 yrs. Always hangared,but always worring,being I didn't do the rebuild. It looks great, Buuuut ? Just wish it didn't take so long to do. Guess that is one reason I am looking for another aircraft. One to fly and one to rebuild.

If the price tag to recover wasn't $10,000 then the first obstical to recovering would be overcome.

If folks could point to an indicator that says "there is a problem there", then off goes the covering.

But what I'm hearing is "it's a good idea", "it's recommended"; of course it's a good idea, but removing a usable covering and incurring a $10,000 expenditure based on no other indications is not reasonable.

Now some of the earlier comments on what was found after fabric removal make me think I need to add items to the pre-purchase inspection; but those items can be checked without removing the entire fabric - Mike

[mhorowit]

Re: Borescope and fabric removal

Mike,
OKAY. No. 2 Now I'm rebuilding a Taylorcraft. ...
So far I have found the following. ...

Many bolts worn and or rusted 1/2 way thru. Ailerons.
One aileron spar (wood) was made out of three pieces glued together.
All the glue was gone and the aileron hinge brackets were the only thing holding the spar together.
Don

Don - would you please clarify a point or so. What did you mean to say in that sentence that starts "Many bolts worn...". The word "Ailerons" standing by itself is confusing me,

"aileron hinge brackets were the only thing holding the spar together" -
At http://www.taylorcraft.info/tcraft/proj240.jpg, Capt Jon
has been nice enough to show us pics of an aileron hinge bracket (see also pic of that bracket later on that same page). You were refering to the spar in the aileron and I don't see how the aileron hinge bracket might be holding the aileron spar together. Did you mean the rear WING spar? - Mike