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Facet fuel pump failures

T

TShort

Well Known Member
I have two of these fuel pumps installed in the -10 for the aux tanks (hotel whiskey style).

https://www.aircraftspruce.com/catalog/eppages/facetpumps.php?clickkey=235826

specifically, model 40178

The tanks have been in place for about a year (first flew after the upgrade in May of last year.)

Since then, I have had 2 failures.
First was a pump that just went bad and quit pumping. These pumps have a distinct sound when running, and the failed pump became very quiet and wasn't transferring fuel.

Yesterday I was getting ready to fly to IA, and filled the airplane. When full, my R tank tends to drip a bit from the vent (not sure the QB tank had the outboard end of the vent tube optimally positioned), but yesterday it kept pouring out. As in gallons (I caught it with a funnel and gas can). The R aux tank was emptying into the main. So the check valve in the pump failed.

I tried to disassemble the first pump, but they are next to impossible to take apart (the innards are potted with a dense foam material).

Are these failures common? Is there an alternative pump that could be used? If these pumps are really that unreliable it makes the aux tanks far less useful, as pump failure either makes the aux fuel unavailable or dumps it overboard.

Boy am I glad I cut into the painted wings and installed the access panels ... replacement is still a pain, but at least we don't have to pull the main tanks every time!
 
Can't speak to the HW installation, but our 1996 DA20 Katana used that same Facet pump as it's main electric pump. We had the plane over 10 years and it's still operating on the original pump. So a single data point of very reliable (4000 hours or so) operation. Used on every takeoff and landing and this airplane was a trainer before we had it.

Only thing I can suspect is the possibility of dry running with the HW tanks versus something we never did in the Katana?
 
Dry running is a possibility, though in my case it would be very minimal; when we did the install, we filled the tanks and timed how long it took to run them dry. I set a timer when I flip the switches, so there is never more than 1-2 minutes max of dry run time.

Plus, I'm not sure how that would affect the check valve ... I don't know what the innards look like.
 
TShort said:
Dry running is a possibility, though in my case it would be very minimal; when we did the install, we filled the tanks and timed how long it took to run them dry. I set a timer when I flip the switches, so there is never more than 1-2 minutes max of dry run time.

Plus, I'm not sure how that would affect the check valve ... I don't know what the innards look like.
Click to expand...

I have four of these exact pumps. I'd wager at 1-2min dry run, youre burning your pumps up. I dont see the dry run spec in their docs, but they are cooled by the fuel, and I rem reading somewhere to keep the pump close to the tank and with a prefilter in-line with it.....might be confusing it with the andair pumps tho....
 
As has been said, extended dry running will eventually cause a coil failure, but like Mani mentioned, trash is a worthy suspect for both failures, if you're not running pre-filters. Trash could cause both failures. It can cause a plunger to stick (no clicking sound & no pumping), and it can also block a valve in the pump.

As Krea said, they typically run for many hundreds to thousands of hours without a problem. The aux pump in my -4 (slightly different model, without PCV) has been there since new in 1991.

Charlie
 
I have two similar pumps to transfer fuel from my wing tanks to my header tank. They have been working fine for the last five years. I did install a crossover valve in case one pump fails, I can use the remaining pump to empty both wings. Were you aware that you're supposed to install a 74 micron filter on the inlet of these pumps? I didn't, but could that be the problem? See: https://www.aircraftspruce.com/catalog/pdf/40105instruct.pdf
 
This is the standard install for the hotel whiskey tanks. I cannot see any way to avoid short periods of dry running unless the tanks are purposefully turned off early and fuel left behind, but this is suboptimal as quantification is difficult. I know now if I run for 35 minutes the tanks are empty and it is exactly 7.5 gallons per side.

How are others with this type aux tank handling the pumps?

I did not install the prefilters. Not sure how I overlooked that, I don't recall it being part of the installation manual for the tanks. I agree that it could be a component of both failure modes.
 
TShort said:
I did not install the prefilters. Not sure how I overlooked that, I don't recall it being part of the installation manual for the tanks.
Click to expand...
Facet only started requiring the filters maybe ten (?) years ago. Before that, the installation instructions didn't show them. I don't have the filters on my installation, either.
 
I had one fail on my RV9, replaced it and put a filter in line before it now. I took the fitting off the end of the failed one and the plunger was stuck in there, tiny piece of trash was caught up in it, it is a very close tolerance area inside where the plunger is. I worked it back and forth a few times and tried it off the plane on a gas jug, it works fine now. I'll probably never use it on a plane again but at least I know what caused it.
 
TShort said:
This is the standard install for the hotel whiskey tanks. I cannot see any way to avoid short periods of dry running unless the tanks are purposefully turned off early and fuel left behind, but this is suboptimal as quantification is difficult. I know now if I run for 35 minutes the tanks are empty and it is exactly 7.5 gallons per side.

How are others with this type aux tank handling the pumps?

I did not install the prefilters. Not sure how I overlooked that, I don't recall it being part of the installation manual for the tanks. I agree that it could be a component of both failure modes.
Click to expand...



Hmmm... You might check your time-to-empty again. I have the same setup on my 10 for over 1600 hours with no problems. But my time to empty is about 25 minutes, not 35. I've checked it multiple tiimes.

Vic
 
Can air circulate around the pump?
I burnt out a series of pumps on the RV-7, eventually cut venting holes in the shrouding and put a computer fan in there to cool the pump. No problems again in the last 10 years other than the fan stopped working, so it appears the pump just needed a bit more ventilation to keep working.
 
snopercod said:
I have two similar pumps to transfer fuel from my wing tanks to my header tank. They have been working fine for the last five years. I did install a crossover valve in case one pump fails, I can use the remaining pump to empty both wings. Were you aware that you're supposed to install a 74 micron filter on the inlet of these pumps? I didn't, but could that be the problem? See: https://www.aircraftspruce.com/catalog/pdf/40105instruct.pdf
Click to expand...

vic syracuse said:
Hmmm... You might check your time-to-empty again. I have the same setup on my 10 for over 1600 hours with no problems. But my time to empty is about 25 minutes, not 35. I've checked it multiple tiimes.

Vic
Click to expand...

Thanks. I went back and looked at the numbers, we recorded 28 minutes and a few seconds. I think I just added some time to account for turbulence unporting the line / etc not realizing that running dry was an issue.

I managed to get the first pump disassembled this evening, will post pics later. Pretty simple device, and I definitely had some debris in there. The check valve is super simple, so I suspect the issue is similar on pump #2.

Vic - how do you manage the transfer? Do you set a timer for 25 minutes and then switch off?

It sounds like prolonged dry running is bad but a bit here and there may not be a big issue.
 
If...

If you want to get fancy, there are time delay relays available that , once started, will automatically turn off after a predetermined time...
 
Or do real sensing with an optical fluid sensor, or with a low-set-pressure pressure switch and a slight restriction in the transfer line after the sense port.
 
ER tanks

I looked at the optical sensor for use with the ER tanks and do to the design of the tanks...I am probably going to put a delay relay in line set for 25 minutes...
 
So it turns out the pumps aren't terribly hard to disassemble (at least the mechanical portion, the electrical components are potted in foam material). Just put a wrench on the fittings and the output side will unscrew.

I found this inside the first "failed" pump:

46280100155_a99e76d90f_z.jpg


Once I removed the aluminum and reassembled the pump works fine.

I do not plan to reuse this in the airplane, the initial attempts at disassembly of the body of the pump were fairly destructive. Good for education, though.
 
I'm trying to keep things simple in terms of the timer, etc - I just set one on my apple watch, or use the switch tanks reminder or timer in the G3X system.

Now, I just need to figure out how to plumb the filters in there ... the "recommended" ones on ACS have a hose barb, and my aux tank is connected to the fuel pump by an aluminum line and AN4 fittings.
 
I got two from Tom Swerengen at TS flightlines. They are aluminum with AN fittings, high quality with a higher micron rating than the recommended ones and serviceable and not too expensive. I put one in each line from tank to fuel selector for redundancy, in case one should clog and stop flowing. He can also make new high quality flex lines for you to install them. I don't have an aux tank on my plane.
 
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Vic - how do you manage the transfer? Do you set a timer for 25 minutes and then switch off?

There are 2 ways--- a simple clock timer as others have mentioned. or...

Use a DPDT switch for the pump, with one circuit feeding a ground signal to one of the input lines on your EFIS. In my case, I have it tied to the AFS EFIS. I labled it "fuel transfer" and set it for 25 minutes. I get a flashing warning and audio when the time is up.

Of course, I usually forget I have started the fuel transfer, and the big red Engine Warning light illuminating, along with the audio annunciation, usually startles me for a second or 2 until I remember what it is. Needless to say, it REALLY gets my attention at night! Perhaps as I get older I could use it as a nap timer. :)

Vic

Vic
 
TShort said:
I'm trying to keep things simple in terms of the timer, etc - I just set one on my apple watch, or use the switch tanks reminder or timer in the G3X system.

Now, I just need to figure out how to plumb the filters in there ... the "recommended" ones on ACS have a hose barb, and my aux tank is connected to the fuel pump by an aluminum line and AN4 fittings.
Click to expand...

170 driver said:
I got two from Tom Swerengen at TS flightlines. They are aluminum with AN fittings, high quality with a higher micron rating than the recommended ones and serviceable and not too expensive. I put one in each line from tank to fuel selector for redundancy, in case one should clog and stop flowing. He can also make new high quality flex lines for you to install them. I don't have an aux tank on my plane.
Click to expand...

There is a host of filters with AN fittings available in the racing community, here is one source:

https://www.summitracing.com/search/department/air-fuel-delivery/section/fuel-filters/part-type/fuel-filters?N=4294951509%2B4294948059%2B4294948060

https://www.summitracing.com/parts/sum-230102/overview/

sum-230102_ml.jpg
 
Sam Buchanan said:
There is a host of filters with AN fittings available in the racing community, here is one source:

https://www.summitracing.com/search/department/air-fuel-delivery/section/fuel-filters/part-type/fuel-filters?N=4294951509%2B4294948059%2B4294948060

https://www.summitracing.com/parts/sum-230102/overview/

sum-230102_ml.jpg
Click to expand...

What Sam said, tho I use Earls 85micron as prefilters. Lots of places you can get them, just check the specs as they have several micron versions. https://www.speedwaymotors.com/Earls-230206ERL-In-Line-Fuel-Filter-6-AN-Blue-Anodized,142978.html

I also get all my oddball AN fittings from Earls usually - ones I cant source from Spruce. Ones you get that are Jegs or Summit brand, you have no idea who makes them and at least with Earls I have a company I can call for specs etc. Lots of Chinese AN fittings out there.
 
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A word of caution about the Summit filter just linked, and similar designs. It's a beautiful piece of work on the outside, but look at the filter element itself:
https://www.summitracing.com/parts/sum-230102/replacementparts

Authorities I trust say that a disc type filter element will have a very small surface area, compared to typical cylindrical elements. While it may easily flow massive quantities of fuel when it's clean, if you get a load of dirt/trash in the fuel, it can quickly clog enough to block flow. Using one to filter an aux tank could possibly be justified, but I wouldn't want to bet my engine's fuel delivery on one.

Charlie
 
rv7charlie said:
A word of caution about the Summit filter just linked, and similar designs. It's a beautiful piece of work on the outside, but look at the filter element itself:
https://www.summitracing.com/parts/sum-230102/replacementparts

Authorities I trust say that a disc type filter element will have a very small surface area, compared to typical cylindrical elements. While it may easily flow massive quantities of fuel when it's clean, if you get a load of dirt/trash in the fuel, it can quickly clog enough to block flow. Using one to filter an aux tank could possibly be justified, but I wouldn't want to bet my engine's fuel delivery on one.

Charlie
Click to expand...

I agree I would not want one of these filters servicing the entire aircraft. I researched fuel filters recently and studied the filter elements and also noticed the disc element. I would be OK with having one on each tank (but it would take a lot of crud to plug the element or habitually filling the tanks with trashy fuel) but not with having just one filter downstream of the fuel pumps.

Fuel system design should be conducted with much thought about failure modes. Pre-pump filters should have coarser elements than post-pump filters.
 
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Here's an option that a lot of the rotary engine guys use for an injection filter:
https://www.napaonline.com/en/p/FIL3481
Much finer element than actually needed (4 micron), but large surface area. It does need 16x1.5mm to AN adapters:
https://www.summitracing.com/parts/ear-991955erl?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-earls-performance&gclid=CjwKCAiAnsnjBRB6EiwATkM1XjJRtTNYltBb1lmthSB1TP3rUvVm8dwZk1stR18S8c7LmR_G6TDEERoCs0oQAvD_BwE

or search for 'power steering adapter' or 'saginaw adapter'.

Charlie
 
rv7charlie said:
Authorities I trust say that a disc type filter element will have a very small surface area, compared to typical cylindrical elements. While it may easily flow massive quantities of fuel when it's clean, if you get a load of dirt/trash in the fuel, it can quickly clog enough to block flow. Using one to filter an aux tank could possibly be justified, but I wouldn't want to bet my engine's fuel delivery on one.

Charlie
Click to expand...

Charlies point is a valid one of caution - the Earls filters I posted are disc filters, but I use them as prefilters for transfer pumps, not main line runs. Obviously hotrods use them as is, and yeah, trashy fuel for those guys I'd think is rarer than it is for us; volume of product being sold being in their favor.
 
I struggled a bit with the 'coarse before, fine after' principle when setting up my fuel system for my alt engine. I finally came to this conclusion for my purposes: My belief is that the principle arose from the need to keep restrictions to flow reasonably low on the suction side of the pump (to avoid vapor lock, etc), but to maintain utmost cleanliness at the expense of some restriction on the pressurized side. I finally got comfortable with using very fine filters even on the suction side of the pump(s), by using a filter with so much surface area that it presents less restriction than many of the more coarse filters, especially ones with the little disc elements (some are less than half the diameter of the one in that Summit model; no bigger than the end of your finger).


I'm not telling anyone to do as I've done, but many of us have used the little glass cylinder filters (with 1/4" NPT fittings) in low pressure (carb) applications for many years with excellent service. I plumbed one in my current project to filter aux tank fuel before it enters the Facet transfer pump. Those NPT fittings make it very convenient to match in & out to whatever fittings you need. Not 'aircraft quality', but sometimes better is the enemy of good enough. I've gotten great service from 'no name' SLA batteries for a couple of decades, as well. :)

Charlie
 
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rv7charlie said:
I struggled a bit with the 'coarse before, fine after' principle when setting up my fuel system for my alt engine. I finally came to this conclusion for my purposes: My belief is that the principle arose from the need to keep restrictions to flow reasonably low on the suction side of the pump (to avoid vapor lock, etc), but to maintain utmost cleanliness at the expense of some restriction on the pressurized side. I finally got comfortable with using very fine filters even on the suction side of the pump(s), by using a filter with so much surface area that it presents less restriction than many of the more coarse filters, especially ones with the little disc elements (some are less than half the diameter of the one in that Summit model; no bigger than the end of your finger).


I'm not telling anyone to do as I've done, but many of us have used the little glass cylinder filters (with 14" NPT fittings) in low pressure (carb) applications for many years with excellent service. I plumbed one in my current project to filter aux tank fuel before it enters the Facet transfer pump. Those NPT fittings make it very convenient to match in & out to whatever fittings you need. Not 'aircraft quality', but sometimes better is the enemy of good enough. I've gotten great service from 'no name' SLA batteries for a couple of decades, as well. :)

Charlie
Click to expand...

Well Charlie....since you confessed I'll do the same. ;)

After the filter research I conducted, I settled on the glass filters for the wing roots at both tanks. These are to replace the gascolator. I considered the racing filters but the small size of the elements (larger cylindrical element filters are available as well...but they are big...) and the very fine elements (20-30 microns) were a concern due to creating more suction restriction (auto gas) than I liked. The glass filters have 100 micron cylindrical screens which are coarse but fine enough to trap anything that would clog the pump and they are easily inspected by dropping the bottom of the wing root fairing. I may put a small Lexan inspection window in the bottom of the fairings.

Yep, not "aircraft" filters, but I've run these filters for years in automotive applications and never had a failure. There...I feel better.... ;)
 
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A followup on the glass filters. I wouldn't use them on the high pressure side of a fuel injection pump due to uncertainty about pressure handling (not a fine enough filter, anyway), and I'd pay attention to flow rate through them. I found a spec somewhere (since lost) and IIRC, it was around 18-20 GPH. Fine for an O-320, OK for a 360, but that's about it. And they'll obviously flow less if they start to clog, like any filter.

Like anything, know your application and the product.

While trolling for specs just now, on Amazon I saw several larger filters (for 'racing') in aluminum with the same basic design concept as the glass filters, but with 0-ring threads on the ends and a selection of A/N adapters. Might be worth a look, if you have room and would prefer an all-metal filter. Caution; at least one shows fuel flow in the wrong direction in the ad.

Charlie
 
I had a Facet pump fail on the way to OSH a few years back. It's under the co-pilot seat to feed the right main to the header. It was a low time pump but it decided not to work for some reason. Long story short, I had to remove the seat and hit the pump with a crescent wrench every time I wanted to transfer fuel. From Vegas to OSH.. Went to Spruce at OSH, bought a new pump, replaced it and it's fine ever since. Oh well.. It happens.
 
So these are definitely sensitive to any debris; I pulled the one that failed, and there are a couple of tiny aluminum shavings in there. Cleaned out, all is good / functional again.

Is there any reason the pump cannot be re-used after it is disassembled? It is a simple matter to unscrew the boss and remove the spring and plunger and reassemble; I don't see any locking mechanisms, and the bosses are not staked or anything else.

I was thinking of keeping the one I removed and cleaned as a spare, since I already bought a replacement...
 
maniago said:
These are exceptional. But man, what a price tag......seems way over the top for what it is. That said, the Andair filter are at least as expensive.....
Click to expand...

I guess everything is relative, I thought the price seemed pretty reasonable!
 
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