At least there are reasonable solutions for much of this if one chooses
to go the extra mile. I'm pretty sure that down to -6 bulkhead fittings
are acceptable in aluminum on the firewall but I can''t seem to find the
reference.
I'd like to find an equivalent for the asbestos packing/washers that
used to be used to protect grommets in the firewall. I'll try the
fibrefrax ceramic cloth for that unless someone has a better idea. The
metal swivel (or non swivel) throttle cable passthroughs are nice but
something cheaper might be even nicer ;)
Another weird one I've noticed is the use of 5/8" hardware store nylon
plumbing fittings on water cooled engines to cabin heaters and such. At
operating temperature they lose more than half what strength they had
let alone if an overheat occurs.
Ken
Wayne G. O'Shea wrote:
Ken, dug through my pics and the lip I put on Fullers actually sticks out 1
1/2" to pick up the windshield retainer and still leave enough lip for the
cowling to sit on, but the windshield itself would not sit out past the
original firewall stainless lip.
Your totally right about all the places that fire could enter the cockpit,
but I was just spelling out the firewall integrity of the lip itself. The
problem of this "fireproof" firewall and it's associated fittings, where
does the inspector/builder stop making it a sealed unit. It used to be
alright to put primer lines etc through grommets so there wasn't all those
extra fittings to leak/buy etc. Now some inspectors snag you if you don't
have bulkhead fittings (and they must be steel if under 1/2" I believe it is
(don' t quote me), but it's still just fine to run the throttle, mixture and
carb heat cables through a grommet, so what's the difference??. What's next,
are they going to expect everyone to put $$$ MIL spec Canon connectors on
all the wiring as well, like in a military installations (as my UTVA's
have). Next all of our heat box controls are going to have to be stainless
and either way it's a gapping 2" hole through the firewall.
Ever look at a Kitfox/Avid flyer? The fiberglass cowling is what closes off
the entire top section of the firewall from the cabin. Could never figure
out how they could pass something like this, and in the next heartbeat
ground Toby/George's because it had an aluminum firewall and then after the
fiberfax installation they still questioned the glue they used to install
same!
Wayne
----- Original Message -----
From: <klehman@albedo.net>
To: <murphy-rebel@dcsol.com>
Sent: Thursday, November 27, 2003 9:12 AM
Subject: Re: Windshield hanging over firewall lip - Rebel/Elite
Wayne you got the shelf even smaller than me then. My shelf is not
permanently rivetted in yet because I made the first one out of aluminum
for easy fitting/trimming and sorting out how to do it. I figured I'd
end up making it more than once anyway. I have stainless sheet metal
here for it, but I will likely just add a little ceramic firecloth as I
am having trouble motivating myself to install the stainless. In my mind
the windshield and 0.020 cowl top are both very little protection from
fire anyway and ceramic cloth is supposed to be acceptable. I'm sure
Curt would add that yes seconds do matter when it comes to fire so I'll
do something there. Then there are the two shelf support brackets which
should probably be stainless as well. rivets?
The inspector also recommended covering the firewall flanges with red
silicone where they rivet to the to the aluminum skins. Seems a bit
Mickey Mouse but better than nothing I guess. I'll at least use
itumescent caulk there.
Then there are all those 2" aluminum cabin heat control valves.
Stainless valves are available but usually I see aluminum ones installed
and we can guess how long that will keep a fire out of the cockpit. Well
maybe a few seconds longer than the big nylon electric wire passthrough
grommets that are becoming popular. I've elected to use 1.25" inch
stainless bathroom grab handle elbows with firesleeve as per Bob
Knuckoll's recommendation for the wires. OK I'm venting a bit but it
seems that most firewalls look to be there to survive a quick glance
from the inspector rather than be effective for slowing a fire...
Ken
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