Front spars that are to long

[Mike Davis]

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Date: Tue, 23 Feb 1999 14:44:17 +0800
From: Philip Craig <philip@airplan.com>
Organization: AirPlan Aviation Technical Services Inc.
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Mickey,
WAIT!!!
I noticed by your Rebel number (534) that you are close in number
to my own (518) and I had the same problem. I talked to MAM and
found that there was a batch of front spars that were not trimmed
to the right length before the holes in the end were drilled and
subsequently shipped. I followed the instruction in the manual
and found while attempting to line up the leading edge skin, that
the distance from the root rib to the first pre drilled rib (ie
not the rib you place at 6" from the root rib) was almost 1/2"
longer then the distance between any of the other ribs. Serves
me right for following the directions! When I contacted MAM,
they said they would replace the affected spar or I could drill
out the rivets holding the spar and shift the spar the correct
distance. I chose to do the latter but I added a doubler plate
and a angle bracket on each rib/front spar connection.

I would guess that Tim has used the pilot hole to gauge where to
drill the holes for the 1/4" bolts. As I recall (it has been a
while since I did this) the manual suggests measuring the
distance in from the edge of the spar and the distance measured
is more then ample for what is required. Therefore regardless of
where the factory drilled the pilot holes, the measurements
should suffice.

Anyway, if you are going to leave the extra length on the front
spar at the root end, then you can not follow the method used in
the directions. The manual calls for you to place a block of
wood against the end of the spar and make a number of
measurements from there. As the spar is too long then measured
distances will not be right. I would suggest that you (as
suggested by MAM at the time) trim the front spars to length or
use the holes for the 2nd rib and measure back to the root. I
would prefer the second method and trim the excess front spar a
bit closer to the time you are ready to start riveting the front
spar.

Carry on riveting!
Philip
R 518

--
Philip Craig
Aviation Planner
Halcrow AirPlan
philip@airplan.com
www.airplan.com