Anyone here managed to squeeze a maintenance shutoff valve (normally safety-wired open) and an inline fuel filter into their wing root area? I'm trying to figure out how to squeeze mine in there and I'm just not having luck.
I'm also considering just having the valve in the wing root and then the filter in front of the spar, and draining it out at the wing roots before pulling the filter.
Do a search on this topic and I think you'll find several threads and opinions. My fuel system will be "non-standard" whatever that means and here's why:
1.) Canada has a requirement for a gascolator in the system, whether carb or fuel injected. This is non-negotiable, no matter what you think of gascolators. I consider them to be inspectable (drain before flight to make sure fuel comes out and not something else) fuel filters that have a bypass built into them.
2.) I am using a certified style Weldon high pressure fuel injection boost pump because it is the most reliable cost effective pump I could find. The pump manufacturer recommends a fuel filter upstream to protect the pump. To address this requirement I'm installing an Andair "gascolator" in each of my wing roots. There is maybe more room in the RV-9A wing roots than others. Yes it's a tight fit, but I did a mockup with real parts and am going with them.
3.) Precision Airmotive who makes the Silver Hawk fuel injection system recommends a fuel filter upstream of the servo. Can't remember the micron rating off the top of my head, but it is finer than most inline automotive filters that many install in the cockpit. I sourced a Falls Filtration "gascolator" which features a cleanable filter element, a quick drain for preflight inspection and a clogged filter bypass valve. This gascolator is used in the Beech King Air and similar ones are used in Piper Navajos.
So my fuel system consists of;
Van's finger screen (not the sawcut aluminum tube) in the fuel pickups
Andair GAS375 gascolator in each wingroot
Andair LEFT RIGHT OFF fuel selector valve
Weldon high pressure boost pump
Falls Filtration gascolator mounted on the firewall right side low where the Van's filter for carbs is normally mounted
Lycoming engine driven fuel pump
Precision Airmotive fuel injection servo, spider and lines
This the safest, most reliable, most inspectable, most redundant system I could design that met the micron requirements of the pump and fuel injection manufacturer's recommendations and the Canadian regulatory requirements
I rejected the idea of using shutoff valves in the wingroots so there would absolutely be no chance of them being turned off or vibrating to the off position. The research I did led me to believe that if the fuel tank is below about 1/3 full that the fuel would not siphon through the wing root filters while they are being serviced. Airplane is not finished yet so I have yet to verify this.