Mod 49 adds a second fuel filter and relocates the filters under the seats
where they are much easier to access for cleaning.
I had fitted the optional tank drains so I swapped the port and stbd F09C's to
place the angled output toward the center; without the drain, the F09C's could
be rotated in place 180 degrees. This orientation makes the routing of the
hoses somewhat easier.
I used a Greenlee 5/8 inch chassis punch to make the holes in the seat back
and tunnel after drilling 1/4 in pilot holes. These holes were then adjusted
with the Dremel. It worked out that the holes were elongated horizontally and
sort of angled through the fiberglass at about 45 degrees to accommodate the
hose routing. Edges were rounded with the Dremel and then smoothed with 220
grit.
Pieces of nylon spiral wrap were installed onto the hoses where they pass
through the fiberglass to minimize wear. The hoses were cut so that the filter
axis is parallel to the spar -- a 12 inch hose from the tank to filter and a 6
inch hose from filter to valve was about right. The long hose from tank to
filter facilitates clamping the hose while changing the filter (see question
below).
A holder was fashioned for the filter from a 4 inch section of 1 inch radiator
hose by removing a 180 degree piece 2 inches long from its center to provide a
viewing window. The 1 inch sections at each end were cut through to form
flaps which retain the filter while allowing it to be extracted from the
holder easily. The idea is to protect the glass, prevent it from rattling,
and allow easy inspection.
In the US there are many odd things added to our auto gas to minimize
emissions and these chemicals apparently cause some fuel lines to deteriorate.
So I called my DAR to ask about using the fuel line available at auto parts
stores in place of that supplied by Europa with the idea that this would be
more resistant to chemicals in auto gas. He said that this would be fine and
offered an interesting technique for making standoffs for fuel and electrical
lines from fuel line. Cut a 1/4 to 1/2 inch section of fuel line, put a tie
wrap around a support, pass it through the section of fuel line, around the
item to be secured, and back through the section of fuel line. This results in
the tie wrap taking on a figure 8 shape with the fuel line section forming the
waist. The fuel line is rigid enough to hold things apart and soft enough so
that it doesn't abrade them. An option if a line is passing by a support at
90 degrees is to use 2 tie wraps which intersect within the section of fuel
tube. Perhaps this is a well known technique, but it was new to me so I
thought I'd pass it on.
Naturally, some questions arose as part of Mod 49...
To ease installation I wipe a bit of grease inside the end of each hose prior
to installation. Should grease also be applied to the O rings in the ends of
the filter to ease tightening? (Directions which came with the filter don't
mention this)
When cleaning the filters I assume that the line to the filter will be clamped
using locking pliers since fuel to the filter can no longer be shut off with
the valve. I tested the Europa fuel line and that from the auto store for
recovery from clamping and the auto store line seems to recover its shape
nicely after release while the other remains somewhat oval (Does this
matter?). Is clamping the accepted method while cleaning the filter or must
one drain the tanks?
While Mod 49 simplifies filter access it does bring fuel into the cockpit. If
a leak should develop in a filter while the aircraft is parked, fuel would
gather under the seat until it rises to the level of the hole for the hose
when it would seep through and presumably run down inside the fuselage and out
the hole at the rear bulkhead.
I expected to use blue foam as the seat support under the cushions but this
would dissolve in the gasoline, possibly plugging the opening around the hose
and at least making a terrible mess as it drained toward the tail. Should a
material other than blue foam be used as the seat support and if so, what?
Would a polycarbonate window in the seat support to facilitate filter
inspection be worthwhile? Should a 1/4" drain hole be drilled from the seat
pan into the tunnel?
Regards, John A044 Newtown, CT
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