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Jim4
Joined: 15 Dec 2008
Posts: 4
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 Posted: Sat Jun 05, 2010 12:59 pm Post subject: Fwd: List Introduction & Main spar falls off workbench |
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Hello RV'ers,
I've been lurking, reading, and building an RV7A slow build since
2007. I thought I'd introduce myself to the list prior to my first
request for help!
Well it took till getting the fuselage kit for the first major problem
to strike: a comedy of errors, on which I would truly appreciate some
advice:
Assembling the main spar center section, I had just constructed and
temp bolted the wood spacer blocks between the fore and aft main spars
to check for fit.
Things looked good and I left the center spar on the workbench for the
night. Unfortunately, I left it on a piece of foam which gradually
compressed and the spar fell off the table 3 feet to the concrete and
linoleum floor!
The first floor strike appeared to bend a corner of the spar web down
90 degrees on a 45 degree bias. This is on the forward left lower side
of the front spar web (where the 7A gear leg will go through later)
I just knew it was stressed and would crack bending it back and it did
when bent about half way back. I stop drilled the crack #30 and bent
it the rest of the way back flat. I then sanded and scotchbrited a
smooth slot.
My question is (and I will ask Vans):
This is a small crack, but it is in a BAD place (1 inch to main spar bolts).
Is my fix OK? Is there a better solution? This piece is matched to my
left and right main wing spars and wings are 90% done. Is it
impossible to get a new center section front spar?
Looking at the drawings, I note:
Both the forward bottom skin and the aft bottom skin overlap this
lower spar web flange at the front spar (lots of skin thickness here).
Are there no stresses on the corner of this web at this location?
The landing gear leg on the 7A will require scalloping a bit of this
flange away anyway, but that scallop area (approximated by red pen in
picture) is closer to the second rivet hole than the first. I got
excited when I saw this as I thought I might cut my error away anyway,
but it looks like the scallop will miss the damaged area.
Well so much for you all thinking highly of me on my first intro. I've
been pretty careful so far and not many mistakes or drilled fingers,
but boy is this a bummer. Could it have happened on a worse piece?
Thoughts, comments, fixes, and good natured laughter are appreciated.
Best regards,
Jim Clark (Gainesville, VA)
BTW, for some additional comedy: the bucking bar followed the spar off
the table (in the same event) an put a nice dent in the center of the
web to add insult to injury. This is not a show stopper though.
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Vanremog(at)aol.com
Guest
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| Posted: Sat Jun 05, 2010 3:35 pm Post subject: Fwd: List Introduction & Main spar falls off workbench |
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Just my quick observation is that this appears to be in an area that is under virtually no stress. My 6A has the old laminated 11g spar, so I can't be certain about your situation with the new wing spar. I would take the whole broken area off and smooth the edge transition so that no crack could propagate from the edge. What attaches to the small holes on the flange?
-GV
In a message dated 6/5/2010 2:03:06 P.M. Pacific Daylight Time, james.s.clark(at)comcast.net writes:
| Quote: | Hello RV'ers,
I've been lurking, reading, and building an RV7A slow build since
2007. I thought I'd introduce myself to the list prior to my first
request for help!
Well it took till getting the fuselage kit for the first major problem
to strike: a comedy of errors, on which I would truly appreciate some
advice:
Assembling the main spar center section, I had just constructed and
temp bolted the wood spacer blocks between the fore and aft main spars
to check for fit.
Things looked good and I left the center spar on the workbench for the
night. Unfortunately, I left it on a piece of foam which gradually
compressed and the spar fell off the table 3 feet to the concrete and
linoleum floor!
The first floor strike appeared to bend a corner of the spar web down
90 degrees on a 45 degree bias. This is on the forward left lower side
of the front spar web (where the 7A gear leg will go through later)
I just knew it was stressed and would crack bending it back and it did
when bent about half way back. I stop drilled the crack #30 and bent
it the rest of the way back flat. I then sanded and scotchbrited a
smooth slot.
My question is (and I will ask Vans):
This is a small crack, but it is in a BAD place (1 inch to main spar bolts).
Is my fix OK? Is there a better solution? This piece is matched to my
left and right main wing spars and wings are 90% done. Is it
impossible to get a new center section front spar?
Looking at the drawings, I note:
Both the forward bottom skin and the aft bottom skin overlap this
lower spar web flange at the front spar (lots of skin thickness here).
Are there no stresses on the corner of this web at this location?
The landing gear leg on the 7A will require scalloping a bit of this
flange away anyway, but that scallop area (approximated by red pen in
picture) is closer to the second rivet hole than the first. I got
excited when I saw this as I thought I might cut my error away anyway,
but it looks like the scallop will miss the damaged area.
Well so much for you all thinking highly of me on my first intro. I've
been pretty careful so far and not many mistakes or drilled fingers,
but boy is this a bummer. Could it have happened on a worse piece?
Thoughts, comments, fixes, and good natured laughter are appreciated.
Best regards,
Jim Clark (Gainesville, VA)
BTW, for some additional comedy: the bucking bar followed the spar off
the table (in the same event) an put a nice dent in the center of the
web to add insult to injury. This is not a show stopper though.
|
[quote][b]
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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Jim4
Joined: 15 Dec 2008
Posts: 4
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| Posted: Sat Jun 05, 2010 3:46 pm Post subject: Fwd: List Introduction & Main spar falls off workbench |
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These holes on the flange are on the bottom and rivet to the forward
lower skin and the rear lower skin. The two skins overlap both the
front spar (problem area) and the rear spar.
I agree after studying the plans a bunch that this last rivet hole is
not likely to be under much if any stress.
Do others familiar with the 7A spar agree?
If I remove the 1st rivet hole, or the first and 2nd rivet holes on
the flange, should I replace this with a similar thickness backer
strip of aluminum when riveting the skin overlap in this area?
Other opinions?
Thanks,
Jim
On Sat, Jun 5, 2010 at 7:33 PM, <Vanremog(at)aol.com> wrote:
| Quote: | Just my quick observation is that this appears to be in an area that is
under virtually no stress. My 6A has the old laminated 11g spar, so I can't
be certain about your situation with the new wing spar. I would take the
whole broken area off and smooth the edge transition so that no crack could
propagate from the edge. What attaches to the small holes on the flange?
-GV
In a message dated 6/5/2010 2:03:06 P.M. Pacific Daylight Time,
james.s.clark(at)comcast.net writes:
Hello RV'ers,
I've been lurking, reading, and building an RV7A slow build since
2007. I thought I'd introduce myself to the list prior to my first
request for help!
Well it took till getting the fuselage kit for the first major problem
to strike: a comedy of errors, on which I would truly appreciate some
advice:
Assembling the main spar center section, I had just constructed and
temp bolted the wood spacer blocks between the fore and aft main spars
to check for fit.
Things looked good and I left the center spar on the workbench for the
night. Unfortunately, I left it on a piece of foam which gradually
compressed and the spar fell off the table 3 feet to the concrete and
linoleum floor!
The first floor strike appeared to bend a corner of the spar web down
90 degrees on a 45 degree bias. This is on the forward left lower side
of the front spar web (where the 7A gear leg will go through later)
I just knew it was stressed and would crack bending it back and it did
when bent about half way back. I stop drilled the crack #30 and bent
it the rest of the way back flat. I then sanded and scotchbrited a
smooth slot.
My question is (and I will ask Vans):
This is a small crack, but it is in a BAD place (1 inch to main spar bolts).
Is my fix OK? Is there a better solution? This piece is matched to my
left and right main wing spars and wings are 90% done. Is it
impossible to get a new center section front spar?
Looking at the drawings, I note:
Both the forward bottom skin and the aft bottom skin overlap this
lower spar web flange at the front spar (lots of skin thickness here).
Are there no stresses on the corner of this web at this location?
The landing gear leg on the 7A will require scalloping a bit of this
flange away anyway, but that scallop area (approximated by red pen in
picture) is closer to the second rivet hole than the first. I got
excited when I saw this as I thought I might cut my error away anyway,
but it looks like the scallop will miss the damaged area.
Well so much for you all thinking highly of me on my first intro. I've
been pretty careful so far and not many mistakes or drilled fingers,
but boy is this a bummer. Could it have happened on a worse piece?
Thoughts, comments, fixes, and good natured laughter are appreciated.
Best regards,
Jim Clark (Gainesville, VA)
BTW, for some additional comedy: the bucking bar followed the spar off
the table (in the same event) an put a nice dent in the center of the
web to add insult to injury. This is not a show stopper though.
|
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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ceengland(at)bellsouth.ne
Guest
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| Posted: Sun Jun 06, 2010 1:13 pm Post subject: Fwd: List Introduction & Main spar falls off workbench |
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Obviously, Van should have the final word. But I'll bet they tell you to clean up the edges of the crack & build on. It's hard to imagine that one rivet doing a lot to keep the plane in the air. Take a look at edge distances & see if you can add a rivet outboard (toward the corner), & one between the original outboard pair.
Adding a doubler there looks like it would be difficult, with the gear weldment in that space.
Charlie
From: James S Clark IV <james.s.clark(at)comcast.net>
To: rv-list(at)matronics.com
Sent: Sat, June 5, 2010 3:56:56 PM
Subject: Fwd: List Introduction & Main spar falls off workbench
Hello RV'ers,
I've been lurking, reading, and building an RV7A slow build since
2007. I thought I'd introduce myself to the list prior to my first
request for help!
Well it took till getting the fuselage kit for the first major problem
to strike: a comedy of errors, on which I would truly appreciate some
advice:
Assembling the main spar center section, I had just constructed and
temp bolted the wood spacer blocks between the fore and aft main spars
to check for fit.
Things looked good and I left the center spar on the workbench for the
night. Unfortunately, I left it on a piece of foam which gradually
compressed and the spar fell off the table 3 feet to the concrete and
linoleum floor!
The first floor strike appeared to bend a corner of the spar web down
90 degrees on a 45 degree bias. This is on the forward left lower side
of the front spar web (where the 7A gear leg will go through later)
I just knew it was stressed and would crack bending it back and it did
when bent about half way back. I stop drilled the crack #30 and bent
it the rest of the way back flat. I then sanded and scotchbrited a
smooth slot.
My question is (and I will ask Vans):
This is a small crack, but it is in a BAD place (1 inch to main spar bolts).
Is my fix OK? Is there a better solution? This piece is matched to my
left and right main wing spars and wings are 90% done. Is it
impossible to get a new center section front spar?
Looking at the drawings, I note:
Both the forward bottom skin and the aft bottom skin overlap this
lower spar web flange at the front spar (lots of skin thickness here).
Are there no stresses on the corner of this web at this location?
The landing gear leg on the 7A will require scalloping a bit of this
flange away anyway, but that scallop area (approximated by red pen in
picture) is closer to the second rivet hole than the first. I got
excited when I saw this as I thought I might cut my error away anyway,
but it looks like the scallop will miss the damaged area.
Well so much for you all thinking highly of me on my first intro. I've
been pretty careful so far and not many mistakes or drilled fingers,
but boy is this a bummer. Could it have happened on a worse piece?
Thoughts, comments, fixes, and good natured laughter are appreciated.
Best regards,
Jim Clark (Gainesville, VA)
BTW, for some additional comedy: the bucking bar followed the spar off
the table (in the same event) an put a nice dent in the center of the
web to add insult to injury. This is not a show stopper though.
[quote][b]
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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