Thanks for all the great inputs!!!
Sorry for the long post...
Don't be mistaken, I'm not on an anti-gascolator campaign...
Just trying to reason the why and how instead of blindly doing something.
For what I understand, a gascolator is a very good element to have as a water separator and filter.
My issue is that with the 10 micron uncloggable filter after the boost pump (to protect the injectors) , I don't see the use of a gascolator (with a 70 micron mesh) FWF. Not to mention that with the 8's engine mount, there is not that much space on the lower firewall...
So I understand putting 1 before the boost pump to catch the debris that went through the fuel pick-up mesh in the tank.
That means just after the selector, in the cabin. Not my preferred solution, more on this further down.
Hence my planning on putting 1 in each wing root as Bevan and others did.
But that implies increasing the complexity of the system, and I'd like to avoid that.
As for water, I can see 4 possible ways (there may be more) that it can pollute the fuel.
- Condensation in tanks (removed by draining pre-flight)
- Leaky fuel caps when parked outside in rain (removed by draining, cured by changing caps)
- Contamination while refueling (this is always a risk, of course mitigated by draining afterwards)
- Condensation in the remainder of system (IMO, this is unlikely to happen as all the system should remain primed with fuel, especially if check valves are installed)
Gascolator in the cabin:
The main (new) issue here is this heads-up I got from Robert Paisley of Protek (flyefii):
It would be best to use a positive locking drain valve on the gascolator. You don't want a push-to-open valve in the suction side of the fuel system. These can get sucked open by the pump and cause air to enter the system.
The Protek boost pump continuously delivers approx 30 GPH.
If I remember correctly, (memory tends to fade after some years... :roll eyes
on some Piper aircraft there was this drain valve that had to be ¼ turned before it was possible to push in. I assume this is what Robert is talking about.
In the cabin, with the gascolator near the floor, I believe it would be awkward to operate while catching the fuel for inspection.
Maybe I'm wrong here and over-thinking it...
On the regulatory side, I may understand where the gascolator requirement comes by reading from the Normal, Utility, Aerobatic And Commuter Category Aeroplanes
(only (a) & (b) are relevant here...)
523.997 Fuel Strainer or Filter
There must be a fuel strainer or filter between the fuel tank outlet and the inlet of either the fuel metering device or an engine driven positive displacement pump, whichever is nearer the fuel tank outlet. This fuel strainer or filter must:
(a) Be accessible for draining and cleaning and must incorporate a screen or element which is easily removable;
(b) Have a sediment trap and drain except that it need not have a drain if the strainer or filter is easily removable for drain purposes;
The magic words here are : draining, easily removable, sediment trap, drain, drain purposes.
There doesn't seem to be a waiver for this in the Amateur-Built Aircraft chapter (549).
I didn't see any...