Chris

 

I haven't seen Al's flow schematics, however with two different intake levels and only one pump per level,  there is no redundancy if the secondary pump has a mortality and the fuel is lower than the primary intake level..

 

Consider the main pump running dry (with a bunch of unused fuel waiting for the aux to pump it), hit the switch for the aux pump, if you get nothing---- you got nothing but unusable fuel for the ride down. An aux aux pump would even things up numerically.

 

Now consider that, unless he is consistently running his tanks until the aux pump is needed, that pump is idle, most of the time. My guess is that an unused pump has a greater possibility of failure than one that is constantly used/lubricated and possibly heated to drive off moisture.

 

Now, if my interpretation of your interpretation of Al's system is incorrect, delete the above.

 

This begs the question.. with two pumps, both feeding from the same tank level, might it be prudent to alternate which is the main and which is the Aux each flight?.

 

When I used to fly twins, it was my habit to start the starboard engine first  for one flight and the port first for the next.

 

This had the effect of equalizing the running of the engines, it also had the ability to detect a bad starter (if the sequence were correct --50% chance) without having to have the "good engine" running before you make the decision  to scrub the trip.

 

This will be my MO for pump operation in My Aerocanard

 

Rich

 

I am using two fuel pumps.  The Aux was always quieter.  Now they sound about the same.  I guess since, IIRC, the primary was always louder I "assumed" it was normal and was just limited to the individual pump.

 

I was just reviewing Al Wick's sight. He hates the rotary (ok, that may be too strong, but he is not a fan).  He is using a Subaru.  I was looking at his sump tank.  He is using in the tank pumps, which I do not wish to do as of right now.  However, something he did which I did kinda like was that he had his pumps drawing from different levels in the tank, like my motorcycle does for it reserve.  That way, if the primary pumps runs dry, you can switch to the second pump and have a bit more fuel....hopefully at least enough to pull your head out and get on the ground.  This seems pretty easy, especially with inline pumps, to do and like a good idea. Seems as if you would just have to have one pump out location higher than the other and you have a bit of a reserve.  Yeah, you should be paying attention to fuel management but this seems like some cheap back up. However, I could be missing something as currently I am feeding both pumps from the same outlet. Thoughts?

 

Chris

---

From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Bill Bradburry [bbradburry@bellsouth.net]
Sent: Thursday, August 16, 2012 10:15 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel pump replaced

Chris,

Is there a difference in sound between the new pump and the old one you are still using?  I think that they should both sound the same.  Mine do.

 

Bill B

 

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From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris Barber
Sent: Thursday, August 16, 2012 10:43 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] fuel pump replaced

 

I replaced my faulty fuel pump.  The new pump is MUCH more quite.  I suspect the old one was on the way to failure for a while and finally when belly up.  It was really noisy.  When I took it off I applied power to both independently and the old one was just plain dead.

 

I hope I have addressed the few gremlins that has kept me on the ground the last few weeks and will get to fly later today.

 

FWIW.

 

Chris Barber

Houston KEFD

Velocity SE