FACET pump & air (fuel) flow

Camillo · #1 06-07-2008, 09:18 AM

I just (re-)installed FACET fuel pump, after fitting Aeroquip hose. Original tubing was not so good and it touched the floor, so I also changed tubing.

Before attaching definitively tubing on pump and torque nuts, I blew inside the pump and noticed that air flow is very difficult: you have to blow quite strong to obtain little air to pass through (far less than the normal air flow inside the tubing itslef). I'm wondering if this will cause problems to fuel flow when FACET pump will be off or if it breaks suddenly during take-off. Maybe engine pump will produce enough depression to suck enough fuel. I'm a bit worried...

Norman CYYJ · #2 06-07-2008, 03:28 PM

Should be no restriction. Any I have blown thru are easy and no sense of a restriction. Blowing the wrong way and there sure is.

osxuser · #3 06-07-2008, 10:43 PM

I don't like the little "box" facet pump at all. It has a failure mode that blocks fuel flowage to the engine, even if the mechanical pump is working fine. I much prefer the FAA Approved style...

http://www.aircraftspruce.com/catalo...rupterpump.php

And they aren't THAT expensive.

Camillo · #4 06-08-2008, 07:00 AM

Norman, I'm not sure if I blew in both directions. Maybe I tried from the wrong way. I will check it asap.
Thanks.
Camillo

Norman CYYJ · #5 06-08-2008, 09:39 AM

I have just dug up an old pump which does not work and blown in it. It does have a slight restriction in the direction of the fuel flow but not enough to cause any grief. In the other direction it is impossible. There is a check valve in these pumps.

Camillo · #6 06-16-2008, 07:40 AM

Ok. I just checked it yesterday and you were right. Fuel flows only in one sense. I only tried the other sense. I felt very stupid!

Now, with all connected and safetied till gascolator, I tried to blow on the tubes - one per time - at the location where they enter in the fuse, with fuel selector ANDAIR installed. Air passes, but no so easily as if you blow in a single piece of tube (I mean, each single piece of the fuel routing tube). I guess it should be enough. Anyway, I will tried pressure before flying...

Thanks again.
Camillo

Jamie · #7 06-16-2008, 09:09 AM

Quote:

Originally Posted by osxuser

I don't like the little "box" facet pump at all. It has a failure mode that blocks fuel flowage to the engine, even if the mechanical pump is working fine.

Could you elaborate some more? There has been a lot of misinformation spread around about these pumps. People would probably be interested in hearing some hard facts.