<not taken into account is that the fuel flow of an aircraft is significantly greater than that of a car

Not true in this modern age. 30 years ago would have been true.

They do take high flow into consideration. They design the systems to handle the extremes. When we do qualification testing we measure how close we are to failure threshold. "Holy crap, if this guy has partially clogged filter similar to ones we find on Kentucky cars 15 years old. AND he is running at full throttle. AND he has replaced injectors with high flow ones..........no, he's still within the safety margin."

Have to admit, I don't know the details of Mazda fuel flow thresholds. But I do know Japanese companies are expert at design optimization. They do measure how well sys will perform in unusual applications. We have what's called a "noise array" and test how well sys handles unusual situations outside of our control. So high flow injectors would be in the noise array. As would fuel from "Bob's rusty tank".

Would flow for 600 hp engine be considered? No, not that extreme.

<filter/pump were removed inspected and cleaned, I personally would feel much better about that installation.

Yes, I think a lot of people are not used to the concept of a design so robust that failures can't occur. In the case of OEM fuel filtering, it's totally unnecessary to remove and inspect. If curious, use one of those scopes to peer into tank. In this case, remove and inspect would increase risk. I love the irony.

-al

----- Original Message -----

From: ARGOLDMAN@aol.com

To: Rotary motors in aircraft

Sent: Tuesday, August 07, 2012 7:39 AM

Subject: [FlyRotary] Re: Fuel Filters. Was: Rotary Forced Landing

Al,

Of course, what is not taken into account by the auto guys is that the fuel flow of an aircraft is significantly greater than that of a car and that old planes are still flying and don't have the opportunity to "pull over to the side if the filter gets plugged totally or partially.

Now if, as part of a conditional inspection, the filter/pump were removed inspected and cleaned, I personally would feel much better about that installation.

Rich

In a message dated 8/6/2012 10:58:34 P.M. Central Daylight Time, alwick@juno.com writes:

Dave says:

<How does a filter "Self clean"?

I mentioned this a couple years ago. One of the guys called Bull Sh__. Well, not really, but what he did was most impressive. He went to local wrecking yard, bought two used coarse filters. They reside in the fuel tank. I think he spent like $5 or so.

Then he puts it in bucket, no I think he has old aquarium. Attached a pump to it. Then got some dirt and debris from yard and poured it on. As I recall he could not get it to clog. But the self cleaning was obvious when he added a little wave action and vibration to it.

If you take this a little further, you can actually measure pump flow rate by timing how long it takes to fill jug. You can then look at jug contents so see how fine it screens. You can add a simple altimeter and measure pressure drop on pump inlet. Less pressure drop means that vapor lock risk is reduced. Tons of stuff you can measure that no one knows.

I'd think you'd find it takes around 1 tsp to clog the traditional aircraft filter...so planes crash. Yet it takes cups of dirt to clog the filter used by every single car manufacturer. Gigantic safety improvement.

<How DO the car manufacturers overcome eventual filter clogging/saturation? Just by making it so dang <large it never reaches that point?

I think they discovered that the larger the surface area, the less likely to clog. That's why they all have around 6 to 10 times more surface exposed to wave action than the filters of yesteryear.

-al wick

----- Original Message -----

From: Dave

To: Rotary motors in aircraft

Sent: Monday, August 06, 2012 6:57 AM

Subject: [FlyRotary] Re: Fuel Filters. Was: Rotary Forced Landing

For the ignorati among us, I must ask.

How does a filter "Self clean"? How DO the car manufacturers overcome eventual filter clogging/saturation? Just by making it so dang large it never reaches that point?

Dave

On 8/6/2012 8:48 AM, Al Wick wrote:

<how small of filtration do we need?

<size of a particle that will fit through the injector nozzle easily?

Excellent questions. You have one resource that stands WAY above others. What do the OEM vehicles use? They know precisely what the optimum surface area is, optimum filtration size. Too fine, it clogs needlessly. Too coarse, you increase risk of injector clog. Too little surface area, it won't last. They even take into consideration unusual needs, like people that operate at super high flow rates.

A few decades ago, cars would periodically suffer clogged filters. Never happens any more because they have new tools to optimize designs. For example, their course filter screen has around 10 times more surface area than any airplane filter. Self cleaning, screen size optimized. So debris can't affect your car. It's just brilliant.

I really worry about builders copying marginal fuel designs. Unaware of how close they are to the failure threshold. You can fly for years with marginal design, tell everyone "works great for me". Unaware you are promoting failure.

-al wick

----- Original Message -----

From: David Leonard

To: Rotary motors in aircraft

Sent: Sunday, August 05, 2012 1:35 PM

Subject: [FlyRotary] Fuel Filters. Was: Rotary Forced Landing

So my next question is how small of filtration do we need? ie, what is the size of a particle that will fit through the injector nozzle easily?

I was using the Earls sintered bronze element at 35microns, but I also could use the SS screen version at 85 mic. The Peterson in line 600 series is MUCH more expensive and comes in 45, 60, and 100 micron SS screens.

http://www.jegs.com/p/Peterson-Fluid-Systems/Peterson-600-Series-Fuel-Filters/1528539/10002/-1

Those do have more surface area but will be a hassle for me to retrofit, and not sure they are worth 4x the price of the earls. Lots of other brands I have not explored yet.

I like the sintered bronze for strength and durability. Other opinions?

Dave Leonard

On Sun, Aug 5, 2012 at 12:42 PM, David Leonard <wdleonard@gmail.com> wrote:

Yea, mine is an Earls cleanable high pressure with maybe 10 sq cm worth of area. Will look into the Peterson. Thanks Tracy.

Dave Leonard

On Sun, Aug 5, 2012 at 10:48 AM, Tracy <rwstracy@gmail.com> wrote:

Al probably means the filter that's on factory in-tank pumps. OK, but very hard to implement on RV wet-wing tanks. I used a gascolator for low side filter on my -4. Worked OK and when it clogged, switching on the backup pump with main pump caused the screen disk to collapse and let fuel bypass it. which is better than no fuel at all but not an ideal solution.

On the -8 i used a cleanable Peterson filter with TONS of filter area, works great. That was a replacement for the Summit Racing fuel filter with a filter element disk the size of a nickel. It clogged up in about about 5 hours of flight.

Tracy

Sent from my iPad

On Aug 5, 2012, at 10:18 AM, David Leonard <wdleonard@gmail.com> wrote:

Yes, it was the high side filter. I don't have any low side filters. Would be interested in a source for the self-cleaning fool-proof low side filters that Al mentions.

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net

On Sun, Aug 5, 2012 at 6:34 AM, Tracy <rwstracy@gmail.com> wrote:

I assume Al is referring to the pump intake side filter. So for the record, was it the inlet side or the high pressure side filter that clogged? ( Both are needed ) >From the symptoms I'm guessing high side but not sure.

BTW, nice job!

Tracy

Sent from my iPad

On Aug 4, 2012, at 3:53 PM, "Al Wick" <alwick@juno.com> wrote:

As long as your are rebuilding, tremendous safety improvement by using same fuel filter method that all cars use. No matter how much foreign material you throw at it, it can't clog. It minimizes pressure drop, so lower risk of vapor lock. Self cleaning filter. Self priming pumps.

-Al Wick
Cozy IV powered by RDM Subaru 3.0R.
Expert at failure prevention methods, N9032U 240+ hours from Portland, Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.ez.org/pages/alwick/index.htm

----- Original Message -----

From: Jeff Whaley

To: Rotary motors in aircraft

Sent: Saturday, August 04, 2012 1:38 PM

Subject: [FlyRotary] Re: Rotary Forced Landing

Dave, having gone through recently what you just experienced I would like to say GOOD JOB on getting down safely and with such little damage. Anyway at 1500 AGL there isn't a lot of time ... obviously you made the right choices.

Jeff

(Rebuilding my Ride)

From: David Leonard <wdleonard@gmail.com>

Subject: Re: [FlyRotary] Fw: Fw: [FlyRotary] Rotary Forced Landing

Date: Fri, 3 Aug 2012 06:18:47 -0700

To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Sigh..

Yup, that was me. I have been meaning to fess up. We were at about 1500 agl when the fuses blew on my fuel pumps. I was in a close formation of 40 aircraft at the time too. I think I got some bad MOGAS somewhere in Iowa as I did notice my fuel return flow creep downward but didn't think it was a big problem.

On the incident flight, a one hour formation flight from SQI for a mass arrival at OSH, the return fuel flow drifted down to zero. I actually though it was a sensor problem. I didn't have the ability to give it a lot of attention because we were in a loose formation. Soon after we pulled it together for a tight formation power switched off. I tried to find a road, but quickly ran out of options and put it down in a bean field. With the beans hitting the flaps it brought me to a stop in about 200ft, just before I would have gone into the full grown corn. As mentioned, wheel pants broke in half but no other damage besides pulling bean leaves out of every nook and cranny. The farmers were very nice, and the stories are true... they have attractive daughters. They were out there barefoot in their Sunday best enjoying the excitement. Helped me clean the fuel filter and replace the fuses. Within a couple of hours I was able to take off from one of their driveways as they all waived good bye (but strangely, no one took me up on my offer for a ride).

Landed at OSH just before dark to a reserved parking space and a very warm reception from the formation group and friends. Great support from everyone all around, though I am trying to avoid the obvious new call signs they are trying to give me.

--
David Leonard
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David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
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David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net