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jeff(at)westcottpress.com
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 Posted: Tue Dec 05, 2006 12:24 pm Post subject: Confession |
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When the bottom leading edges of the flap skins are riveted to the
flange of the spar, you have to force your hand down between the
skins with a bucking bar to buck those rivets. The bucking bar I
favor is a left over hunk of metal from a printing press. All of the
sides are polished and the edges are polished and rounded. If the
base of the bar is resting on the web while bucking the flange it
will put a slight scar or scuff on the web from the kick back. I'll
usually put a piece of thick tape down on the web or on the bar
itself to keep this from happening. If the access doesn't allow it,
or I flat out forget, I'll hit the spots with a scotch bright pad,
smooth them out, give them a quick shot of zinc chromate and move on.
In the case of my flaps, I did none of the above. I got caught up in
the "moment" (you all know how exciting riveting can get) and put a
neat row of scars across the inner web of my flap spar and buttoned
it up with pop rivets before it even occurred to me.
Can those of you out there with real life experience speak to the
nature of stress cracks... how shy of perfect something can be before
it's a potential problem. In my case, these are more "dent like"
than "scratch like." I'd like to get a sense of what I'm dealing
with here. Should I move on and forget about it? Move on and
inspect it every so many hours once flying? Rebuild the flaps?
I'm hoping, too, that this might give us a breather from the
Eggenfellner thread.
Jeff Carpenter
Thinking I'm Finished with the Flaps
40304
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LloydDR(at)wernerco.com
Guest
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| Posted: Tue Dec 05, 2006 1:10 pm Post subject: Confession |
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If you have ever seen a striped circa 60's plane getting ready for body
work, the amount of dents would scare you. In my opinion small dents are
not as big an issue, if they are not that deep, IE smiley's. If they are
hidden inside a structure and are not visible, and do not mess with the
integrity of the joint, move on. If they are visible, fill them, paint
them and forget about it. If they mess with the structure of the joint
that is a different issue, and a call to Vans is in order, but they will
likely tell you them same thing.
Dan
Hiding smileys on the wings for paint, and no I will never tell where
they are.
--
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owl40188(at)yahoo.com
Guest
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| Posted: Tue Dec 05, 2006 2:12 pm Post subject: Confession |
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Jeff,
It sounds like you have some scuff marks or small dents. If thats the case it should be fine. I would nevertheless check the area for cracks during inspections since the marks are on the spar. What you absolutely don't want is a tear, notch or anything that would give you a higher stress concentration than a standard hole. Those I would personally repair even if the structure is not highly loaded there. Until lots of hours are accumulated on RV10s we won't know where the inherently weak areas are. So far the only one that has come out is on the vertical stab. One other general note is that just because Van's says its okay not to repair something it doesn't mean that they are right. Its not their skin on the line on that particular plane. Another thought is that for typicall commercial aircraft spectrum if you increase the stress by 10% you will approximately halve the fatigue life because life vs stress is an exponential function. The critical areas will typically be at a rivet hole, access hole or another stress riser that's why if the structure has marginal life deburring edges of holes could turn out to be very important. So even a small scratch that touches the edge of a hole should be buffed , removed , cleaned etc..
Niko
40188
---
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AV8ORJWC
Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"
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| Posted: Tue Dec 05, 2006 6:04 pm Post subject: Confession |
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Jeff,
Another example which is great training, is to cut aluminum tubing and take various steps of preparation for a flare. Cut but unfilled with hacksaw marks, filed square, deburred, and polished. Use the flare tool and you will quickly develop skill as well as learn how stress risers cause visible cracks in non-deburred edges immediately after rolling. Edge preparation is a valued skill whether sheet, rod stock, tubing or angle.
John Cox
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Niko
Sent: Tuesday, December 05, 2006 2:11 PM
To: rv10-list(at)matronics.com
Subject: Re: Confession
Jeff,
It sounds like you have some scuff marks or small dents. If thats the case it should be fine. I would nevertheless check the area for cracks during inspections since the marks are on the spar. What you absolutely don't want is a tear, notch or anything that would give you a higher stress concentration than a standard hole. Those I would personally repair even if the structure is not highly loaded there. Until lots of hours are accumulated on RV10s we won't know where the inherently weak areas are. So far the only one that has come out is on the vertical stab. One other general note is that just because Van's says its okay not to repair something it doesn't mean that they are right. Its not their skin on the line on that particular plane. Another thought is that for typicall commercial aircraft spectrum if you increase the stress by 10% you will approximately halve the fatigue life because life vs stress is an exponential function. The critical areas will typically be at a rivet hole, access hole or another stress riser that's why if the structure has marginal life deburring edges of holes could turn out to be very important. So even a small scratch that touches the edge of a hole should be buffed , removed , cleaned etc..
Niko
40188
----- Original Message ----
From: Jeff Carpenter <jeff(at)westcottpress.com>
To: rv10-list(at)matronics.com
Sent: Tuesday, December 5, 2006 3:23:05 PM
Subject: Confession
--> RV10-List message posted by: Jeff Carpenter <jeff(at)westcottpress.com>
When the bottom leading edges of the flap skins are riveted to the
flange of the spar, you have to force your hand down between the
skins with a bucking bar to buck those rivets. The bucking bar I
favor is a left over hunk of metal from a printing press. All of the
sides are polished and the edges are polished and rounded. If the
base of the bar is resting on the web while bucking the flange it
will put a slight scar or scuff on the web from the kick back. I'll
usually put a piece of thick tape down on the web or on the bar
itself to keep this from happening. If the access doesn't allow it,
or I flat out forget, I'll hit the spots with a scotch bright pad,
smooth them out, give them a quick shot of zinc chromate and move on.
In the case of my flaps, I did none of the above. I got caught up in
the "moment" (you all know how exciting riveting can get) and put a
neat row of scars across the inner web of my flap spar and buttoned
it up with pop rivets before it even occurred to me.
Can those of you out there with real life experience speak to the
nature of stress cracks... how shy of perfect something can be before
it's a potential problem. In my case, these are more "dent like"
than "scratch like." I'd like to get a sense of what I'm dealing
with here. Should I move on and forget about it? Move on and
inspect it every so many hours once flying? Rebuild the flaps?
I'm hoping, too, that this might give us a breather from the
Eggenfellner thread.
Jeff Carpenter
Thinking sp; November is the Annual List Fund Raiser. Click on
_"http://www.aeroelectric.com/" target=_blank>www.aeroelectric.com
bsp; * Aeroware Enterprises [/url][url=http://www.homebuilthelp.com/]www.homontribution" target=_blank>http://www.matronics.com/contribution
_p; ://www.matronics.com/Navigator?RV10-List" target=_blank>http://www.matro=======================
[quote] [b]
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