SR Fin Spar Cap MAM Responds

[Don Boardman]

Hi Wayne and all,

My partner Randy sent an email to Brian @ MAM this morning.

MESSAGE TO BRIAN:
Good morning, Don has installed the Fin's internal and external spar caps.
WE THINK WE MAY HAVE A PROBLEM. Given the length of the new external cap
material supplied and placing the bottom of the external cap where it is
shown to start and counting the number of rivets shown above the external
cap to locate the top of the internal cap one finds that THE TOP OF THE
INTERNAL CAP IS LOCATED AT THE FIRST RIVET BELOW THE MIDDLE HINGE RIB. Just
where the drawing shows it being located, if one looks at the rivet line for
the rib in the drawing and ignores the hinge in the drawing.

QUESTION #1
Is the top of the internal spar cap supposed to be above the hinge rib to
tie in the hinge location or ARE WE OK AT ONE RIVET BELOW THE HINGE RIB?

Brian's response:

The way you have it is just fine.....don't want caps and doublers ending at
the same point.

QUESTION #2
We also asked about rivets for the Fin Spar Doublers. We could not find
mentioned of any in the instructions.

Brian's response:

Same rivets and spacing as the Stab. spar doubler. RV-1410's, 1" spacing.

MY CONCLUSION:
Our installation is structurally sound and there is no need to redo to
extend the internal doubler above the mid-hinge point.

THE PICTURES:
So Wayne, what to do with the pictures we have posted?
I definitely think my picture of the bottom layout can be useful to someone
trying to figure out how to install the spar caps.

Question is, do we leave both pictures of our TOP Layouts and let builders
decide? Remove mine and leave yours? The extra height of the internal cap as
you have it surely cant hurt. I do not want to add to future builders
confusion. But on the other hand I do not want builders to go through what
we both have gone through.
??????

Regards,

Don Boardman
& Partner
Randy Bowers
SR130 Rome, NY






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[Wayne G. O'Shea]

Beats me Don as Brian's reply ("don't want caps and doublers ending at the
same point.") <ALMOST> seems to be a contradiction to what you actually
have, as where you stopped the "long" spar cap is only about 3/4" below the
3500 fin spar doublers upper limit as they end at the middle hinges upper
bolts. My way ends about 4+ inches above the doubler. Also, your "long" spar
cap ending point is not much different than the original 2500 spar cap, so
why would a 2500 "flyer" need to rip apart his completed aircraft and do the
spar cap doubler upgrade if this was okay??

LIKE I SAID, "BEATS ME" AND OF COURSE BRIAN G. HAS LAST CALL!! .

Glad you/Randy also asked Brian about the rivets for the face of the Fin
spar doublers. Nothing about them in the upgrade instructions for the fin
and I thought it strange to just leave the overlap un-fastened when I did
the upgrades. I just did all the stabilizer's 3500 upgrades the other day
and noticed these rivets (in one upgrade manual picture showing just the
center hinge area and a little to the left of it) with no mention of them
being drilled or installed in the instructions. I then did these rivets for
the full length on the stab doublers. When I had previously done the fin
doublers I had thrown a couple rivets in just to hold the edge down flat,
but I guess when I pull the rudder off next I had better drill a full
pattern to tie the two doublers together to match the stab.

As for the posted pictures I think we should get Mike to delete your upper
shot, but I'll leave that call to you!!

Cheers,
Wayne G. O'Shea
www.irishfield.on.ca

----- Original Message -----
From: "Don Boardman" <dboardm3@twcny.rr.com>
To: <murphy-rebel@dcsol.com>
Sent: Thursday, February 21, 2002 9:07 PM
Subject: SR Fin Spar Cap MAM Responds

Hi Wayne and all,

My partner Randy sent an email to Brian @ MAM this morning.

MESSAGE TO BRIAN:
Good morning, Don has installed the Fin's internal and external spar caps.
WE THINK WE MAY HAVE A PROBLEM. Given the length of the new external cap
material supplied and placing the bottom of the external cap where it is
shown to start and counting the number of rivets shown above the external
cap to locate the top of the internal cap one finds that THE TOP OF THE
INTERNAL CAP IS LOCATED AT THE FIRST RIVET BELOW THE MIDDLE HINGE RIB.

Just

where the drawing shows it being located, if one looks at the rivet line

for

the rib in the drawing and ignores the hinge in the drawing.

QUESTION #1
Is the top of the internal spar cap supposed to be above the hinge rib to
tie in the hinge location or ARE WE OK AT ONE RIVET BELOW THE HINGE RIB?

Brian's response:

The way you have it is just fine.....don't want caps and doublers ending

at

the same point.

QUESTION #2
We also asked about rivets for the Fin Spar Doublers. We could not find
mentioned of any in the instructions.

Brian's response:

Same rivets and spacing as the Stab. spar doubler. RV-1410's, 1" spacing.

MY CONCLUSION:
Our installation is structurally sound and there is no need to redo to
extend the internal doubler above the mid-hinge point.

THE PICTURES:
So Wayne, what to do with the pictures we have posted?
I definitely think my picture of the bottom layout can be useful to

someone

trying to figure out how to install the spar caps.

Question is, do we leave both pictures of our TOP Layouts and let builders
decide? Remove mine and leave yours? The extra height of the internal cap

as

you have it surely cant hurt. I do not want to add to future builders
confusion. But on the other hand I do not want builders to go through what
we both have gone through.
??????

Regards,

Don Boardman
& Partner
Randy Bowers
SR130 Rome, NY




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