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----- Original Message -----
From: "Marvin Kaye" <marv@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, October 18, 2002 5:52 PM
Subject: [FlyRotary] Re: 20b torque sequence
> Posted for "Marc Wiese" <cardmarc@midsouth.rr.com>:
> Why wouldn't it be almost the same as the 13B? Just criss cross the
> pattern for the number of bolts, if different.
>
> Marc Wiese
>
> > Does anyone have the torque sequence for the 20B?
>
> >> Homepage: http://www.flyrotary.com/
There's a slight complication with the 20B folks:
Some of the bolts don't go all the way through (there's 3), and there are
two different diameters. Keeps the builder guessing. Here's what I did:
Build it back just like Bruce says on his 12B video: "Front" end housing
laying down flat first. Prop this up on 3 4x4s or stacks of 2x4s so that
you can insert the two larger diameter short bolts, and a single small
diameter short bolt in their holes (~120 degrees apart), but not extending
up into the first housing. Make sure that you can get a socket in between
the wood blocking to snug these up.
Stack the first rotor, then the housing, insert the short part of the split
e-shaft, spring load the seals, and stack the first intermediate housing.
Then snug up these three bolts to the first torque step (10 ft-lbs).
Now build the rest of the engine just like you would a 12B. When you get to
inserting the tension bolts into the rear end housing, insert and torque to
10 ft-lbs only the bolts corresponding to the 3 you put in the front end
housing. Then tip the engine down flat (it's heavy!) and start inserting &
torquing in as regular a criss-cross or star pattern as you can make.
Whenever a "medium" length bolt goes into the rear end housing, immediately
follow it up with the corresponding short one on the front end housing.
Two other tricks: Get a paint marker and mark each of the holes "S",
"M", or "L" before you start stacking the whole thing up. This will save
one headache. The other is to use the same paint marker and mark each bolt
head (or on the housing next to it) with it's sequence in the torquing.
This saves a lot of head scratching at the end of a long day when all you
want to do on the 2nd and 3rd passes is "twist-n-go"!
Good luck! The engine is really quite easy to reassemble, and you will be
very pleased with the satisfying "chuff-chuff-chuff" sound it makes as you
bar it over after it's all bolted up ;-)
Tom Kendall
P.S. A little something else I just remembered: There's really 4 different
lengths of bolts. Before you start reassembling, go through all the "long"
bolts and find the one that is ~3/8" longer than all the rest. My bet is
that it is the one really shiny bolt without any discoloration on it. This
bolt goes in one of the two "legs" at the bottom of the housings adjacent to
the oil pan. It won't bottom properly in any of the other holes, and if you
try to torque it there the head will stick out (don't ask how I know... it
should be obvious). Just set it aside and install it in the right hole when
the time comes. Conversely, the other bolts are too short to get any real
thread engagement in that hole.
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