I have had a fuse tank flying in my RV-6 since 2001
Good day, I purchased a flying RV-6 from CA in 2007 and imported it to Canada, it has a carbon fiber Fuse tank behind the instrument panel of 11 gal usable which the builder constructed. It has a nice Andair locking double O-ring flush cap retro fitted to it as well as the standard wing tanks, the filler is situated about 6 inches forward of the base of the windshield. The fuse tank has it's own sump and gascolator and a sight gauge on the panel, similar to the sight gauges of many certified aircraft. The fuse tank feeds into a 4 way fuel valve with Center, left, right and off positions.
The fuel line leaves the valve and goes into a 10 micron stainless filter, then the Facet pump and fuel flow device. When I did the transport Canada climb attitude fuel flow test for importation, this fuse tank fed at a slightly higher rate than the wing tanks, I'm sure due to it's greater head pressure situated above the wing tanks, confirming to me why the POH for this RV-6 lists the center tank on as the desired position for take offs and landings.
I really don't want to get into a heated debate here regarding the safety of 11 gallons of fuel in the cockpit with you, as compared to only having the fuel in the wings, as this is a decision one must make when considering flying the plethora of certified and experimental aircraft with standard fuse tanks. Van's new RV-12 has a 20 gal fuse tank behind the passengers. I have flown Citabrias, Decathlons and Ercoupes with fuse tanks as well as an experimental Spacewalker, so for me, transitioning into an RV-6 with a fuse tank was the same level of risk acceptance.
The pros of the fuse tank are;
The ability to alter your CG forward when you have heavy passengers or want to put more baggage in behind the seats, very nice to have the flexibility of moving 66 useful lbs forward.
11 gallons more range, having said this, when I flew to Oshkosh with it in 2009, after 3.7 hrs in the seat I was ready to land and hadn't run the wing tanks dry, so consider your actual mission carefully, will you really use the extra fuel?
The relative simplicity of the fuse tank as compared to some of the wing tip tank systems I have seen.
The ability to have a visual sight gauge in front of you which is not affected by wing tank gauges and floats perhaps malfunctioning without your knowledge (such as the sticky gauge in the right wing of my new RV-3, obvious when I was looking at it relative to the left wing). What you see is what you get with a sight gauge in the center tank.
The disadvantages will outweigh the advantages for many here;
This tank is in an RV-6 with a tip up canopy, the absolute worst combination for filling the center fuse tank. The tail is down, the avionics bay is exposed with the fill cap 6 inches away. Do not even think about anyone filling this tank except you! I use a small, light, folding step to comfortably see the level, unless someone is in the cockpit. I use a fuel spill absorbent blanket aft of the fuel opening, which blankets the entire avionics bay to prevent any fuel from spilling into this area. Imagine if fuel spilled into this area, what may happen when you turn the master switch on. An A series Vans would have been a much better idea for this style of tank I think. Having said that, neither the builder nor myself have ever had any unfortunate incidents as we have both been VERY careful when fueling. I have about 250 hours in it, with the former builder about the same.
The weight of the tank, even though it is very light carbon fiber, obviously takes away from your useful load, and when full even more so.
The complexity factor increases over the standard Van's fuel system, thus adding more potential failure points.
The presence of this tank increased the difficulty of my import inspection with the Canadian MDRA, as it will for you from your inspector.
This may adversely or positively affect your re-sale value and difficulty re-selling your plane, totally dependent upon whom is looking at it, but I think the more deviations from the Van's proven design, may mean less buyers would be interested in it as compared to a stock fuel system, that is open to debate.
Reduced space behind the panel; I have a decently equipped panel with a SkyMapIIIc coupled to a TruTrak autopilot, back up AvMap EKPIV, Dynon D10, Micro encoder and Micro monitor, dual Microair comms and encoder , backup steam gauges and everything fits fine, although there is obviously much less room to work behind the panel due to the center tank.
To some who read this, you may think why on earth did I buy it, others may think it would be great to have this system. Regardless of your opinion, it will be interesting to read the ensuing posts, please keep them polite and respectful, best regards,
Turned out to be air expanding inside the sealed tank "oil canning" the whole tank and made it sound like a bomb went off. It did this every time he climbed above that altitude.
