RESKINNING
THE SWIFT...
RESKINNING...
From: Bob Runge (ejectr@javanet.com)
Subject: reskinning
How expensive would it be to re-skin my fuselage with thicker skin? I
don't have any idea of the cost of such material. As far as labor, I would
probably assist my A&P with it. Do you need metal rollers etc. to
get the shape started? Why two different thicknesses (.025 and .032).
Is one for the top and the other for the bottom?
Bob,
It's not expensive from a materials standpoint. A couple sheets of aluminum,
one .025 and one .032 Alclad 2024 T3 at a little over 100 bucks a 4' x
12' sheet, and some AN470 AD3-3 and 4 and 5 and AD4-3 and 4 and 5 rivets.
The big thing is the labor, but its not at all hard. You have good access
to all the rivets. They are big sheets, so its kind of intimidating. Change
just one skin at a time. No, you don't need to roll the skins, just cleco
the flat skins in place and rivet on. Back drill the new skins thru the
holes in the old skins. Yes, its a lot cheaper to reskin than to paint
nowadays.
I'm not talking about the bottom
skins. They are .016 (for the longest ones) If they are wavey (and most
are from people crawling in the aft fuselage for 50 years) they don't
show. Most s/n Swifts had .025 or .032 side skins. Yours evidently has
.020. I like to use .032 for the side skins, and .025 for the uppers.
You could use .032 for the uppers, but that skin has about a 90 degree
bend, and it gets a little hard to hold down with clecos. I've done it
though, so it's possible, but harder, and not worth the difficulty. Incidently,
the bottom skin, aft of the centersection is .040. Engineers call that
skin a stress plate sometimes. The later (Temco) fuselages have a larger
gusset at the bulkhead/longeron joint on the inside. (not necessary) If
you get into a project like this there are other things to watch for,
like drilling, drill the skins from one corner to the opposite corner
to keep the wrinkles out. You really only need two size drills, #30's
and #40's. (except drilling out rivnuts, #12. Use an air drill, an electric
drill is too slow. Use hearing protection! It gets LOUD in the fuselage.
Actually, it is necessary for an inside bucker only on the last upper
skin, but most of the rivets are much easier with two people. --
Jim
SWIFT OWNER'S MECHANIC THIN SKINNED
ABOUT RESKINNING...
From: Bob Runge (ejectr@javanet.com)
Subject: Re Skinning
Hi Jim:
I had talked to you in the past about reskinning my fuselage with .032"
on the sides and .025" on the top. Under what authority can this be done?
The reason I ask is that I brought it up to my IA (yep.....the same one
that gave me heartburn over the Brackett air filter that I still haven't
heard a word about from the local FSDO office since November) and he says
that it can't be done legally unless it is under an STC or some legal
change scenario. This is the guy that I hoped would help me with it or
at least supervise my work and approve it. Is it the type certificate
that it was approved under that allows it? -- Bob Runge
Bob,
I sure can't see where THAT would be any problem. Perhaps 95% of all Swifts
manufactured had .032 skin or .025 skin in those locations. So the factory
is the source. Today, you can't just call Globe on the phone, but you
can call the Swift Association, they have much of this stuff documented
in drawings atc. Now finding specific skin gauges may not be as easily
found as I think, but you can try calling Joe. Do you have the Swift Service
Bulletins? Everyone that owns a Swift should. When converting from a GC-1A
to a GC-1B SB #27 tells that when converting an early s/n it will take
more tail ballast because of the lighter skin. (and conversely, a later
airplane will take less ballast because of heavier skin) Or you can take
a simpler approach, and find a later airplane, crawl in the aft fuselage
and read the skin guage off the metal! It is stamped in red ink on the
inside - .025 24ST .025 24ST .025 24ST .025 24ST etc etc etc etc etc,.
By the way, the 1946 designation was 24ST - after 1947 the same stuff
was 2024T3.
I suppose getting a different AI
up there in MA is not too easy. Tell the guy to cool it, I think he's
too nervous! The FAA inspectors will not bother you if you know what you're
doing. The only trouble I've ever had is from young guys who don't know
what they're doing. Usually, the older and more experienced the inspector
is, the easier he is to get along with.
After some more thought, I have some
further comment. The skin gauge on the Swift is not rocket science! I
think a lot of the time Globe used whatever they had, within a gauge or
two. I have seen considerable variance in various s/n Swifts. Also, I
would guess much of that Aluminum was WW2 surplus. Re: my earlier comment
2024T3 was the alloy after 1947, I think even my 1951 Swift has 24ST skin
on it, indicating the metal was made before 1947. Also the rivets are
different on some s/n Swifts, I suppose they were WW2 surplus also. I
think it must have dawned on the engineers it doesn't do much good to
save a couple pounds on lighter skin, then bolt in a 15 lb.block of lead!
Interesting, none of the Big Engine conversions require the heavier skin,
so the .016 and .020 and .025 skins must be adequate. But I still think
I would like to go UP a guage on some of them! -- Jim
CUTTING SHEET METAL FOR RESKINNING...
(10199)
From: Bob Runge <ejectr@javanet.com>
Jim,
Barring the fact of having a sheet metal shear, what would be the best
tool to cut the sheets to size for reskinning the fuselage?
Bob:
Regarding cutting sheets of aluminum... Common aircraft hand shears will
work fine. A set includes a left cut, a right cut, and a straight cut
shear. You can buy all 3 for about 25 bucks. US Tool also has a 14" shear
for about 30 bucks. You will find a left hand will be used about 90% of
the time. When I was younger, I could cut up to .040 Sheet with a small
left hand shear, but I can't anymore. The 14" shear (like a heavy duty
scissors) will cut .040 without any problem. The secret of cutting with
a hand shear is to scribe a line and follow it very closely. (but don't
scratch the aluminum anywhere you are not going to cut!) Then, file it
from three directions, 45 deg. top, 45 deg. bottom and 90 deg. Use a fine
mill bastard file about I" wide. You can make a hand cut sheet of aluminum
look like it was cut in a power shear. To avoid scratches, you can buy
paper covered sheets. (more money) or chromate the metal, then wipe it
clean after riveting.
RESKINNING THE BELLY??? (12299)
Subject: Re: reskinning
From: Larry LaForce <LaForce55@aol.com>
Jim...
I just reread your advice on reskinning. I take it that you do not recommend
replacing the belly skin on the fuselage? The reason I ask is the my long
belly skin aft of the wing already has some filler in places. I plan to
polish 844 and this filler MUST GO!!! Is replacement of this skin out
of the question? If not... what thickness material would you recommend
using? Thanks..... Larry LaForce
Larry,
How bad is it? Painting ( silver or gray) that lower skin does not really
detract from an otherwise polished airplane. That skin is .020 and you
can't really go up in gauge on it, it has too tight a radius near the
aft end. (I suppose you could if you pre-rolled the skin) I wouldn't say
replacing that skin is out of the question, but be aware it's a little
more difficult than it might appear. -- Jim
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