I heartily agree with Fred.
I've mentioned before on this forum my experience with the plastic hydraulic
clutch line on my long gone Lotus Elan - plastic line ruptured, fluid leaked
on exhaust, car caught fire (fiberglass burns quickly) - which is why I
elected to replace the Europa supplied plastic with brass (inside the
fuselage) and stainless steel (down the gear legs) tubing. In the Europa it
is extremely unlikely that a failed brake line could cause a fire but Fred
has it right about the risk of a ground loop, or worse, in the Tri-Gear.
Engineering plastics are great, but only in the right applications (a
"plastic" airframe for example). It is rather tedious to determine the
correct fittings to match the Europa supplied master and slave cylinders,
and fabricate and install rigid metal lines but well worth the effort
because it certainly minimizes risk and contributes to peace of mind.
...and just because I elected to use brass and stainless steel does not mean
that I would find fault with 3003 aluminum tubing in this application - I
don't, as long as it is seamless tubing (and that applies to my choice of
materials also). There are three methods to manufacture tubing and you do
not want to use the scheme that takes sheet metal that is formed round and
the seam welded. Seamless tubing is extruded through a die with a mandrel
to form the inside diameter. The mandrel is pushed through the hot
extrusion billet so there is no seam. Another method is to extrude through
a spider die and that stuff looks seamless to the naked eye but because the
metal flows over the legs of a spider (that holds the mandrel in place)
before exiting the die there are typically three seams, you just can't see
them without sectioning the tubing and doing a metallographic examination -
this is superior to welded tubing but not quite as good a the truly seamless
kind, although it would be perfectly acceptable for the brake lines.
Besides, none of would be able to distinguish these two types of seamless
tubing. The tubing we would use is cold drawn to finished size from
extruded tube.
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 Fred Fillinger
Subject: Re: Europa-List: Brake lines - Parking brake valve
Rocketman wrote:
>
> What is the recommended brake line, for use on a trigear?
> ...
I used 1/4" 3003 aluminum tubing. The reason is finding anecdotes on
kitplane discussion boards about how plastic lines can be problematic.
One is heat generated in the brake ass'y, causing them to soften and
withdraw from the fitting with high braking pressure. May not be the
case with what Europa supplies, but too few trigears out there and the
consequences of asymmetric pressure at the wrong time on landing
roll-out caused me not to use something which would never be approved
on FAA type-certificated aircraft. I don't insure planes for hull
coverage, by avoiding things which make such coverage more appealing.
Reg,
Fred F.
|