REFLECTOR: Fuel Line Routing (was Hub-bub)

[Velocity Aircraft Owners and Builders list]

On 6/22/2014 12:18 PM, Velocity Aircraft Owners and Builders list wrote:
>
> *>In the event of a "traumatic" arrival, with the valve up front, 
> there is fuel essentially in your *
> *>lap*
> Sorry to bring this up again but I’ve been mulling this over in my 
> head overnite and I have to ask this question:
>
> When there is 5 gallons of fuel inside the cockpit area of the 
> fuselage, should this fuel valve arrangement be my biggest concern?
>
> Tom Mann
> N951TM
>
>
The rear fuselage location of the sump tank is in the most protected 
area of the aircraft (in the event of a crash).
While at the factory I was privy to photos and first hand inspections of 
several (avoiding the word "many") Velocity accidents.  None resulted in 
the rupture of the sump tank.
So from a tank rupture point of view, I think the risk is statistically 
minimal.

Leaks from loose fittings and that sort of thing can certainly be a 
concern.  The use of good mechanical practices (proper flaring; torquing 
of B-nuts; secure mounting of the fuel tank; etc) minimizes the risks there.

It's a very good idea, in my opinion, to install a pilot-controlled fuel 
shut off valve leading from the sump tank to the engine side of the 
firewall.

 From my point of view, the presence of a 4 to 5-gallon header tank in 
the cockpit is not much different from the main fuel tanks that share a 
common bulkhead with the cockpit.  I'm more concerned about the 
integrity of Tygon tube style fuel sight gauges as a potential problem 
area than most of the other points in the fuel system.  The idea of a 
youngster playing or shifting baggage snagging an age weakened sight 
gauge tube (which would allow a volume of unchecked dumping of fuel into 
the cabin) is a sobering thought. Statistically, this has NOT been a 
concern either ... but like you, just mulling things over in my mind.  
The Vance Atkinson rigid fuel sight gauge option solves this 
real/imagined concern.

RG aircraft in particular, should mount/recess the sump tank fuel drain 
valve in such a way that it will not contact the runway in the event of 
a gear up landing.  Really - that and using good mechanical practices 
relating to fuel line fabrication and installation are the most 
important safety issues to consider as they relate to fuel in the cockpit.

Scott B.

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