Fuel Filter Fuel Injection System Part 2

I'm still researching fuel filters for the Precision Airmotive Silverhawk (Bendix) fuel injection system. Precision recommends a 32 micron filter in the system and I've found none of the aircraft gascolators meet this requirement. Since Canadian regulations require (a) gascolator, I have an Andair 375GAS gascolator in each wing root. These have a 70 micron rating and satisfy the Canadian regulations but not Precision's recommendations.

Does anybody have any experience with or comments on using the Fram HPG1 5 micron filter or the Aeromotive 12308 Canister Fuel Filter with 10 micron filter? This would be mounted on the firewall downstream of the electric boost pump and upstream of the engine driven pump.

http://www.summitracing.com/parts/FRM-HPG1/
http://aeromotiveinc.com/products-p...8-10-micron-redpolished-canister-fuel-filter/

PS thanks to Walt A for replying to my previous thread.

Fuel Filter Considerations

Wouldn't a small filter media be more prone to ice blockage if you had cold gasoline with some water in it?

john.schwaner said:

Wouldn't a small filter media be more prone to ice blockage if you had cold gasoline with some water in it?

Click to expand...

It is a concern and here's a reference to it actually happening, although within the fuel distributor of a twin engine aircraft.
http://www.tsb.gc.ca/eng/rapports-reports/aviation/2007/a07c0225/a07c0225.asp
The solution in this case was to use fuel additive icing inhibitor. I would do this in winter conditions as well.
The Boeing 777 that landed short at Heathrow a few years back also had this problem, although with jet fuel. It was a very interesting analysis that was on TV a few weeks ago (probably a repeat).
I plan on mounting the fuel filter to the firewall, so it will be operating in air that has been warmed by the engine. Does anyone know how warm this air is?

Fram HPG1

The Fram HPG1 was the standard filter kit included in fuel injection versions of the Glasair I kit, it's a high flow low restriction metal gascolator that uses a replaceable gasoline filter cartridge. I have had no problems with mine and have it mounted on the firewall lower right side with a drain nipple.

Regarding temps in this area, I have a Vision Microsystems temperature sensor mounted aft of the engine near the oil cooler it is in the free stream air, not in the oil cooler exhaust. In the summer I see temps as high as 80C, typical cruise temps in the 50-60C range. In the winter, high temps are around 65C and typical cruise temps in the 40-50C range. With these temperatures in the area around the gascolator, I think it's reasonalble to assume that icing should not be a concern even with a 5 or 10 micron filter element.

Reggie

Terry, I know you probably don't want to hear this but; you seem to be hung up on what Precision recommends vs what has been tested and proven to be effective on nearly every flying RV with fuel injection. Precision only "recommends" that you use a 30 micron filter, now you are looking at filters in the 5 to 10 mcron range perhaps thinking a finer filter must be better and will "protect" the FI system. The Fram HPG-1 uses a paper filter (as do many very fine filters) which are NOT recommended for aircraft use due to succeptability to clogging from water.

The recommendations/plans of the aircraft manufacture always take precidence over the recommendations from accessory manufacturers which are not familar with the specific installation. Van's has approved the AFP pump and filter for the Lycoming engine with Precision injection.

Being that you don't seem to want to listen to the dangers of modifying the fuel system which I previously mentioned in your first thread, I would suggest you call Van's, Don at Airflow Performance (fuel injection guru) or the folks at Bendix/Precision and get the info first hand rather than looking for someone on this site to "bless" your proposed installation.

Sorry if you find this offensive but I'd rather offend you now than read about you in the papers.

Ive been flying the Andair

gascolator as the only filter in my precision fuel system for three years now. Seems to work fine so far.

Comments

Pro's
Easy to change filter media- both location and method
highly filtered fuel??


Cons
heavy
shutdown and parking- hot day, hot ramp, metal canister will be a boiling vessel- the easily volatile components are going to go somewhere. The same phenomenon is at play with any fuel forward of the firewall, but the canister will be a significant volume and the steel wall will transfer the heat to the fuel fairly efficiently (look at a D86 Boiling curve for avgas, 10% of the components could be vaporized at 160 F at ambient pressure).

highly filtered fuel, more so than necessary. Increase potential for plugging

General questions
Is it easy to safety wire the canister so it can't loosen?
Why filter fuel finer than needed? What is the advantage?

First, thanks for all the replies so far.

Reggie, I didn't know the Fram HPG1 was the standard Glasair filter, this kind of information is hard to find. Glad to know you are having success with it. Is the HPG1 used in the Glasair completely standard, or does it have a quick drain added to the canister? Do you use the standard HPGC1 filter element?

Walt, I always appreciate your knowledgeable comments and believe me, no offence taken. I'm an engineer and am used to reading component specifications and then trying to meet them in systems that I design, which is why I take Precision's recommendations seriously. Having said that I found that Diamond uses a single Andair GAS375 (70 micron) in their fuel system for the DA40 with fuel injection, so it is clear that Precision's recommendations are just that. What I would really like to find is a tee type filter with exactly a 32 micron rating, with a cleanable stainless steel mesh filter, with a clogged filter bypass valve and a port for a clogged filter indicator. A filter with these features is fairly common for hydraulic systems, but none of them that I researched were light enough and small enough for my fuel system. I do take the advice about cellulose based filter elements being susceptible to water contamination/clogging seriously. I'm not looking for someone on this site to "bless" a particular solution, but trying to make use of the expertise available to make a better decision. So this thread is still part of my research, and yes, I will consult the sources you suggest.

Stan, yes it is easy to drill the connector bolt between the head and the canister so it can be safety wired. I would prefer a choice of filter elements in the HPG1 so I could choose the 32 micron recommendation, but there is only one filter available with this assembly.

What I am trying to achieve with my fuel system is to have sufficient filtration upstream of the boost pump to protect it from particulate contamination (Andair GAS375 in each wingroot), and sufficient filtration downstream of the boost pump to protect the engine driven pump and injection system from particulate contamination, including contamination from a worn boost pump. I also realize the need to protect against water contamination, which so far includes drain valves in each tank and in each wingroot gascolator.

I do realize that the filtration and coalescing elements in the FBO fuel systems make both types of fuel contamination very unlikely, but I still prefer to design a system to account for unlikely conditions.

I've recently found a fuel filter used on Piper Senecas and Navajos which may be suitable. This is a tee type filter with a removable canister which houses 5 cleanable filter elements. It also appears to have a clogged filter bypass valve. However, both the Senaca and Navaho have the filter located upstream of the boost pump. Does anyone know the filtration rating and pressure rating of this filter?

Terry,
Obviously, you are putting lots of thought into this. Please keep us posted on what you decide.

There are some 30 micron screens here http://www.system1filters.com/oilfilters.htm

They have fuel filters, but the billet oil filters look more like what you are looking for. Bypass is available on some. Drains on some on the fuel filters. Might have to mix and match parts. Most of them are huge, but there is a 3 x 3.25 in or a 3 x 5.25 in. canister replacements.



best

HPGC1 Filter

"Reggie, I didn't know the Fram HPG1 was the standard Glasair filter, this kind of information is hard to find. Glad to know you are having success with it. Is the HPG1 used in the Glasair completely standard, or does it have a quick drain added to the canister? Do you use the standard HPGC1 filter element?"

The Fram unit was modified by the Glasair factory to add a standard aircraft type drain nipple, it has been in use since at least 1987 in 100s of flying Glasairs. I have about 650 hours on my plane and change out the HPGC1 fuel filter about every 100 hours. I have flown in all types of weather, hot and cold from Florida to Alaska. I believe the location I have the gascolator in the engine compartment minimizes the possibility of fuel system icing. Hot starts also have been no problem and I have never had vaporization issues even in 100 plus degree ground temperatures with my Lycoming IO360B1E.

Happy Flying,
Reggie