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Facet boost pump lifespan

alcladrv

Well Known Member
An avgas odor was pretty noticeable the last couple of mornings as I slid the canopy back on my -7A with a carbureted O-360.. Today, I investigated so out came the front carpet and off came the tunnel cover to expose the fuel selector valve and the Facet boost pump.

The inlets to the fuel valve were both good and tight, but the outlet port could be tightened about 1/4 turn. I thought that would take care of the odor.

But, while I had everything opened up, I used the wrenches on the boost pump. The outlet was good and tight. But the inlet on the bottom could be tightened close to a full turn and it didn't seem to bottom out. The problem was that the more I tightened the inlet, the avgas odor became more apparent. I didn't want to overdo it, so I thought I'd let it sit overnight with a white paper towel beneath it to see if avgas leaked out..

The questions are: The pump is 16 years old with typical usage during 1600 hrs. Mostly, I've run avgas, but have used no ethanol 91UL on occasion. Do these pumps have a typical lifespan? Does mogas use shorten the lifespan? If I continue to tighten the inlet until it noticeably bottoms out without getting it overly tight, will I harm the pump or worse split the fuel tubing and create a very noticeable leak?

Until now, the fuel system has worked normally without any issues.

Thanks!
 
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Not sure, but I have two on my plane

So, I will watch this post closely, as I depend on the very reliable little square pumps more than most. I run two of them on my carbureted O320H2AD, one as "full time" fuel pump, the other as boost/backup pump. I do not run a mechanical pump because the H2AD mount boss would have caused an unsightly (to me) bump in my upper cowl. I have been running these pumps for 11 years and about 400 hrs. with no issues. Curious to see others observations.
 
well, my ship sports 1 engine driven + 2 facet pumps, all of em 2005 vintage. One of the facet is used for take-off, then switched off in the cruise, the other one is then switched on for landing.

The mechanical pump still delivers a reliable 4psi, the facets up to 6.

Re your fuel leak, I would not tighten anything anymore. Better make sure all mating surfaces and the tubing flared ends are good. I’ve never seen a properly tightened AN fitting work itself loose...yet.
 
But, while I had everything opened up, I used the wrenches on the boost pump. The outlet was good and tight. But the inlet on the bottom could be tightened close to a full turn and it didn't seem to bottom out. The problem was that the more I tightened the inlet, the avgas odor became more apparent. I didn't want to overdo it, so I thought I'd let it sit overnight with a white paper towel beneath it to see if avgas leaked out..

Thanks!

The flare may be cracked, if so you won't be able to make it stop leaking until you replace that line.

In regard to your service question, my 1999 Facet pump is still working. I've wondered if it would be prudent to replace it but I'm more concerned about "infant mortality" of a new (off-shore?) pump.
 
well, my ship sports 1 engine driven + 2 facet pumps, all of em 2005 vintage. One of the facet is used for take-off, then switched off in the cruise, the other one is then switched on for landing.
/QUOTE]

I have to ask, what is the reasoning behind the dual boost pumps?

Chris
 
Thanks for all of your responses.

I just got it an order from Aircraft Spruce. Are there any other sources of the 3/8" fuel tubing besides the usual aviation suppliers?
 
Chris, talked some about fuel systems in this thread https://vansairforce.net/community/showthread.php?t=191331

The original builder designed the fuel system with dual el pumps and a return line for the use of Mogas and to lessen the chance of vapor lock. Dual facet for redundancy. Despite all of this I’ve had vapor locks on ground and in flight a couple of times... my bad each time since I had either el pump off :eek:
 
New fuel line in order.

I agree with Sam on this one. The tubing is soft aluminum and the fittings are steel. If it still leaks after tightening that much, something is definitely wrong.
Also there is a chance the flare wasn’t made correctly to begin with and over time has failed. Replacing the line with proper flares will probably solve your problem but use proper torque when tightening. They can crack a lot easier when the flare has been over tightened.
 
If your known properly flared AN fittings want to leak. You need to get some Del-Seals and use them as a sealer for the flare. Obviously they won't seal a cracked fitting, But those are rare.
They will sometimes not seal if the surfaces aren't just right. Del-Seals are spendy soft aluminum, But, work real good for a slightly rough fitting.
Aircraft Spruce has the best price on the 1/4" and 3/8" aluminum tube I could find. I usually buy 50 feet at a time so I don't feel pinched for supplies.
Art
 
Beware new Facet pumps

Recently it was reported that Facet had manufactured a batch of pumps with incorrect port flare angles that would almost guarantee a leak. A builder friend had to buy and return three of them from ACS to get one with the correct flare angles. There is at least one thread on this subject on VAF.
 
The little square facet pumps should be pretty reliable...more than the mechanical one. They're solid state, and the only moving part is the piston...see video...

https://www.youtube.com/watch?v=Dtf66p8M11g

I agree they "should" be very reliable, but could fail. I went to a class a week ago and the instructor discussed the fact that these pumps could and have failed in the closed position (blocking fuel flow). Without some sort of bypass and if plumbed in series, that would obviously stop fuel flow and cause engine stoppage, even if you also have a mechanical pump plumbed in.

Has anyone plumbed in some sort of bypass that would allow bypassing the Facet pump, if failure was to occur during flight?

The pump for my RV12 is a $44 part. Considering that I use mogas with ethanol, I'm thinking it would be prudent to replace the pump every few years during Condition Inspection just to make sure I'm not slowly building up some sort of gunk/debris in the pump that could cause it to fail and block fuel flow. $44 for such a critical part is pretty cheap piece of mind insurance.
 

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850 hours

At the 850 hour mark, the Facet 40108 driving the mechanical pump on my O-320 went to humming rather than clacking. I run it for take off and landing. The new one from Spruce makes the appropriate racket again. And I noticed a bit higher pressures both off and on. Blowing through the bad one proved difficult... so there may have been a restriction effect. Being the curious type I took apart the bad one. Mostly potted around the magnet coil, so could not see much. There did seem to be a semiconductor embedded there. Maybe that switches current off and on to create the pulses? Pretty simple design with a couple of springs and check valves.
I was surprised it gave up the ghost with relatively low hours, though it was put in service in 2006.
I think I will put it on my list for 5 year replacements... they are sure cheap compared to most airplane parts prices. ( I put the paper that says not for airplanes in the shredder.... shhhhh)
 
Pump

Not an RV but my Facet pump is pipe thread on both ends, so AN 816 or equivalent to adapt to aluminum line. If you overtightened the AN fitting you may have split the end of the pump housing.
 
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