There is an elegant solution at
http://www.aeroelectric.com/articles/Firewall_Penetration/firewall.html that
I have used for my 914 installation. After agonizing over how to stuff
those rather large connectors through the firewall I found this method by
participating in the AeroElectric-List; - see
http://www.aeroelectric.com/consulting.html for more info. I would urge all
builders to participate in this list and to get a copy of "the book" by Bob
Nuckolls, http://www.aeroelectric.com/Catalog/pub/pub.html#aec9
Being really paranoid about cutting big holes in the firewall, I have used a
slight modification of the feed-through suggested by Bob. Using a standard
12 inch long, 1.25 inch diameter, 304 stainless steel "grab bar" from
McMaster Carr http://www.mcmaster.com/ (p/n 2823K32, US$19.05) as a starting
point, I cut off both flanged "elbows" and then cut each along its
centerline to create a matched set of top and bottom pieces (actually I had
to cut slightly off centerline because of the saw kerf, and discarded the
two smaller pieces - four "halves" make one set). Now I had a split elbow
that would allow passage of the large connectors on the engine side of the
firewall through a minimum size hole in the phenolic firewall, and by using
a stainless steel hose clamp at each end of the elbow, both halves of the
"clamshell" were reunited. The rest of the scheme follows Bob's method.
The flange is sandwiched to the firewall by a large phenolic washer cut from
the material removed prior to installation of the landing gear mounting
frame.
Rotax has a strange concept of how their engines will be installed. Most of
the cables from the TCU have connectors neatly installed by the factory at
each end which discourages cutting them to length, and splicing just adds
another connection that may eventually fail. The two cables from the TCU
through the firewall to the pressure sensors are so short that it is almost
impossible to make them reach, and others such as the connections to the
waste gate servo are ridiculously long. It is essential that the location
selected for the TCU, the pass-through, and the bracket for the pressure
sensors be chosen very carefully or the cables will not reach. The waste
gate arrangement is particularly bizarre because it is tethered by a
mechanical linkage that is much shorter than the electrical cables.
Neither the Rotax installation manual nor the Europa engine installation
manual hints at how to make the short cables reach.
Another point about locating the TCU - keep it away from the avionics stack
or it will interfere with deep radios such as the GarminAT (formerly UPS
Apollo) CNX80 and SL70, each of which is too deep to fit the standard
(unmodified) Europa panel even with the TCU out of the way.
Rob Housman
A070
Best regards,
Rob Housman
Europa XS Tri-Gear A070
Airframe complete
Irvine, CA
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of paul stewart
Subject: Europa-List: thro the fire wall
<paul-d.stewart@virgin.net>
This engine (914) is throwing up more questions then the whole of the
project so far. Having disconnected the TCU and wastegate servo to mount
them aft of the firewall, the manual very succinctly tells me to make
holes as small as possible and use a suitable method of sealing.
I'm guessing that folk make holes to take the pressure sensors etc.
rather than the large TCU block connector through the fire wall. What is
a 'suitable method' of sealing - anyone got a pic or two. I suspect
seeing this sort of thing would be a great help.
Regards and thanks in anticipation
Paul #432
<META content"MSHTML 6.00.2800.1226" nameGENERATOR>
<STYLE></STYLE>
This engine (914) is throwing up more
questions
then the whole of the project so far. Having disconnected the TCU and
wastegate
servo to mount them aft of the firewall, the manual very
succinctly tells
me to make holes as small as possible and use a suitable method of
sealing.
I'm guessing that folk make holes to
take the
pressure sensors etc. rather than the large TCU block connector through
the fire
wall. What is a 'suitable method' of sealing - anyone got a pic or two.
I
suspect seeing this sort of thing would be a great help.
Regards and thanks in
anticipation
Paul
#432
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