I find it interesting to reference the Europa design to U.S. rules for
production A/C, and seems like there's problems.
Each tank (unclear whether the reserve saddle is a separate tank, but
in spirit of the rules, seems it is) much have a separate, drainable
sump of 8 oz. each. You must also have one drainable sediment bowl of
at least 1 oz. capacity in the fuel line.
I note FAA's "unusable fuel" rule has nothing to do with denying water
and contaminants to the system. The volume is established with
reference to all permissible flight maneuvers, meaning just no
stoppage with any fuel above usable (as in a slip). Theoretically it
could be almost zero. Thus, the tank must be designed so that any
"hazardous" quantity of water will drain into the sump "in normal
ground attitude." Not just into any gascolator; that will occur only
after fuel is flowing in flight.
As Carl Pattinson points out, water is best kept out the system in the
first place, by filling up after a flight and not before to the extent
possible. Water else can accumulate over successive filling cycles.
A common scenario in U.S. accident reports is where no water drains in
pre-flight, but in a subsequent flight attitude (Cessna bladder tank
problem, e.g.), it starts flowing. Further it takes finite time for
water put into the tank to settle (as in brief and contaminated fuel
stop), the stuff should be trappable somewhere, and a gascolator as
sole backstop has insufficient capacity, at least per these Regs.
Where I think the Europa design is thus faulty (besides no sump) is
its slanty tank bottom, but one recommended tank drain design. May be
OK for the monowheel, but I question the tri-gear, where water may
undrainably accumulate near the outlets. Everything's fine, until one
day the descent for landing!
BTW, other possible regulatory "busts" are the single vent for a
single tank, the unprotected sight gauge and associated plumbing, tank
in the crew compartment, lack of grounding to the filler cap, and only
electric pumps on the 914. The supplied filters might comply only
through redundancy.
Regards,
Fred F., A063
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