Jabiru fuel filter empty.

[440032]

Here's an odd one that has me rather stumped.

Jabiru 2200, over 500 hours. Have always used RYCO fuel filters, the simple plastic ones. Changed each 2 years.

2019 annual, I fitted the JOYWELL filter as supplied by Jabiru. Soon after, I now realise, I started having occasional rough idle. Open throttle, all good.

In the past, the fuel filter usually sat at about 2/3 to 3/4 full. Today, and I've seen it recently too, fuel filter was totally empty. I don't understand how that is even possible.

Removed it and found the filter cartridge inside was loose, detached from the fuel OUT end, rattling around inside the plastic case. I cut it open to mess around with it.

No fuel leaks anywhere, I just don't understand how the filter can be empty and the engine still runs. The Joywell filter has a double size hose nipple for 1/4 or 5/16 hose. I'm going to fit a Cooper filter, 1/4 inch hose size.

I have the standard engine pump, and the standard Facet elec boost pump.

Any fuel filter theories out there? Why is my filter empty.

Thanks!

[skippydiesel]

Fuel filter sounds like a pleated paper (medium) type - if this be correct, no offence 440032, in my humble opinion your just asking for trouble using that type - ok for lawn mowers etc -  I would use one on anything larger .

 

Aircraft should only use gauze filters or those supplied by aircraft/engine manufacturer.

 

The best disposables I have found are :

 

Hengst 102 WK

Hengst 103 WK

 

[440032]

Pleated paper type - yes. I like to keep things simple and use what it's supposed to have Skip.

I have used what was recommended by the engine manufacturer for the last 16 years, no problem. I shall fit the new Cooper filter probably tomorrow, and report my findings.

Will also be looking at a few other things, fuel pump too. Fuel pump is higher than the filter, so it's not draining up hill. Got me stumped.

 

Those Hengst filters look good - I shall read up on those.

[Thruster88]

I have used Ryco z15 fuel filters on the thruster since about 1993 without any problems and that's with premix. I dont like dirt going in the engine and it is amazing what the paper catches when cut open for a visual inspection. I do have a fuel pressure gauge.

[skippydiesel]

2 hours ago, 440032 said:

Pleated paper type - yes. I like to keep things simple and use what it's supposed to have Skip.

I have used what was recommended by the engine manufacturer for the last 16 years, no problem. I shall fit the new Cooper filter probably tomorrow, and report my findings.

Will also be looking at a few other things, fuel pump too. Fuel pump is higher than the filter, so it's not draining up hill. Got me stumped.

 

Those Hengst filters look good - I shall read up on those.

I first came across this type of filter when I went trough a prolonged love affair with Mercedes, W 123, 300D, (diesel cars). Gauze prefilters were fitted. It turns out that the are several suppliers but Hengst is one of the few that make (actually manufactured in Israel) their casings transparent & almost indestructible.

 

I later found that ATEC  (the maker of my aircraft) are  fitting them in their factory built aircraft.

 

They are not designed as a serviceable components- however bit of carbie cleaner, and a high pressure air blast, usually removes any accumulated matter.

[onetrack]

FWIW - It pays to remember that if you get even a small amount of water in your fuel, it will block those pleated paper elements very rapidly.

I'm amazed that Jabiru recommend the use of a paper pleated fuel filter, and particularly a cheap plastic one.

 

Re the "empty-looking filter", this is the result of a vapour pocket. In the link to a discussion below, a poster named "mownie" posts an initial reply which is largely correct, but his reply is very convoluted, and the problem is not clearly outlined.

But "mownies" second reply, further down the page, more clearly outlines how the vapour pocket appears, and how it is common to see. His second answer starts with, "I have observed this phenomenon for decades now".

 

https://www.houzz.com/discussions/1661558/fluid-dynamics-of-an-empty-looking-fuel-filter

[440032]

Thanks onetrack - heading there to that for a read.....

[nomadpete]

Well after reading that other thread about "empty" fuel filters, I now understand how the filter can end up filled with vapourised fuel. But I still don't get how the engine still runs when there is no liquid fuel in the fuel filter cavity. Isn't that just a vapor lock?

[onetrack]

It is vapour, but it's not a lock as we know it. The fuel is still flowing, but vapour is forming in the filter canister - which vapour is not transferring to the fuel line.

A vapour lock is a serious amount of vapour in the lines that won't return to the liquid phase, and which causes engine stoppage.

But the vapour in the "empty" filter is just a vapour bubble which easily transitions back to liquid. I would have to opine the temperature of the line and the reduction in pressure caused by fuel pump suction are the two major factors at work, with the pressure reduction probably playing the primary part.

 

Edited October 6, 2021 by onetrack

[440032]

I fitted new Cooper filter today. Test idle for 10 mins, all good. Took it for a flight, all good. Took cowl off, filter about half full, which as far as I recall, is about the normal level.

Filter pics. Cut the old one open, shows where the cartridge had come off the whatever at the OUT end, possibly restricting flow on the IN end, and the OUT end. Maybe.

Engine idle in flight today felt rock solid, back to normal. Will continue to watch carefully.....

 

[facthunter]

 I wouldn't use a filter where the bit the rubber pipes fit on doesn't have barbs. If your filter is at the high point of a fuel run it's more likely to show  air/vapour. If it passes through to a carburetter it's just vented after it passes the float needle.  If it's fuel injection it's another matter. Cavitation at a pump intake is a worry. Nev

[skippydiesel]

If you use the correct hose size : push fit, length and support your filter (dont let it hang or move about) "barbs" are completely redundant. They give the bad mechanic that warm & fuzzy glow  from being sucked in by a marketing gimmick.

 

No offence 44032 but I would never ever use a filter of the type shown, any where near an aircraft (or engine above 5 hp)

[Thruster88]

This is a fuel filter from a 1100 hp turbine ag aircraft, pleated paper about 150mm long. All the fuel has to flow through it. The pt6 engine also has a paper filter in the fuel pump.

 

[skippydiesel]

4 hours ago, Thruster88 said:

This is a fuel filter from a 1100 hp turbine ag aircraft, pleated paper about 150mm long. All the fuel has to flow through it. The pt6 engine also has a paper filter in the fuel pump.

 

Yeah! fully tested/certified for use in that application - not much similarity to the B&S mower filter, probably made in some Asian sweat shop, by 5 year old kids, in 44032's example.

[facthunter]

Many of those paper filters were treated with a plastic material to make them stand water. Ryco used to state this and the Paper  product was made in South Africa at the time. Now many of what we buy is made anywhere but here. It would be worthwhile to know how "good" the paper is.  If you have a small area doing the filtering you wouldn't want it to be very  fine as it could block up pretty quickly .Nev

[onetrack]

I am in full agreement with Skippy. The paper pleated element that Thruster shows is aviation-grade pleated paper, which almost certainly is of a much higher quality and specifications than the regular el-cheapo plastic fuel filter that 440032 is using.

This aviation-grade filter paper that Thruster pictured, would have specifications for the paper material that covered the type of paper, the paper treatment, and the level of filtering ability - which quite likely allows some water through.

The filter is also of a much larger diameter, with a vastly increased surface area for filtering. It doesn't take much of an increase in filter diameter, to add a substantially increased filter surface area.

 

Engines will run quite happily with a small percentage of water in the fuel - but they won't run at all, with a totally blocked filter. I've had extensive experience with the cheap plastic filters in automotive applications, since the 1960's.

They're good to stop trash entering carbies and jets - but they will plug completely, with even a modest amount of water, making the engine stop.

I've taken those filters off when I've had engines that were showing signs of fuel starvation - and even though they looked just fine, you couldn't blow through them, they were totally blocked.

 

To that end, Skippys recommendation of the Hengst filter is a far better choice for an aircraft, where you cannot afford an engine stoppage caused by a $5 cheap paper fuel filter becoming plugged.

The Hengst filter has the major advantage of stopping the trash that will block jets and cause a loss of engine power - but it will let through any water that might have gotten into the fuel system, thus largely eliminating blockage problems.

 

One has to keep in mind at all times, that water is with us everywhere, and gets into everything. If you're using automotive fuels, there's an allowance in the Fuel Standards Act for water content in fuels. It's a very low level, yes, but it's there, regardless.

Then, once fuel is being handled, it picks up moisture from the air. When you draw fuel from your drums and fuel tanks, air with moisture in it, replaces the fuel used.

You have water drains on your tanks to try to eliminate any water from your fuel, but the potential is always there, for some water to get through.

Accordingly, when aviating, you're in a safer position, when you utilise fuel filters that have a vastly reduced capacity to totally block up.

 

Edited October 6, 2021 by onetrack

[Thruster88]

A properly designed aircraft fuel system will not allow water to get to the fuel filter / gascolator. This relies on the pilot doing the tank drain before the first flight of the day and after refueling. I have verified the un useable fuel on my aircraft by pumping the tank dry with the boost pump and then emptying with the drain valves. Have never had water reach the filter / gascolator.  

[facthunter]

The water takes time to settle out of the fuel. and long thin fuel tanks may retain some water because they aren't designed with any kind of sump that directs the water to the drain point or downstream to drain somewhere else. There may be a required sequence to a drain process. Really,water should not get into a carburetter. While the main jet may handle it corrosion in the idle passages can render the carb unrepairable. Mostly aero carburetters are made from al/zinc alloys with brass jets. With water these form a galvanic couple and corrode. Water forms a white powder uild up in small passages in the carb body many of which can't be accessed to clean them as they have permanently installed plugs at corners. Nev.

[Flightrite]

I’ve been using the cheap & nasty filters for ages, Changing them every 50 hrs and filtering my gas thru a Mr Funnel every time, never seen dirt or water anywhere👍

[440032]

Cheap and nasty, and specified in the Jabiru Maintenance manual (though not with those words of course - generically speaking).

I've always used quality RYCO filters since 2005, for about 500 hours, now sadly, RYCO now gets their stuff manufactured who knows where.

I bought the Jabiru filter primarily to see exactly what it was. Brand X. (Joywell - Taiwan).

I see where I work that many brand name car parts are manufactured wherever too, Indonesia, Mexico, Portugal, Thailand, and of course C.H.Ina. Oil filters?- throw a dart at a world map.

[Ian]

On 06/10/2021 at 9:49 PM, skippydiesel said:

If you use the correct hose size : push fit, length and support your filter (dont let it hang or move about) "barbs" are completely redundant. They give the bad mechanic that warm & fuzzy glow  from being sucked in by a marketing gimmick.

I won't comment from a push fit perspective however when used with a clamp a barbed or raised fitting does provided a significant mechanical advantage and added safety, you can also buy aviation clamps with safety wire holes which should give you an extra feeling of safety if you've ever had a fuel hose come loose.

The following kitplanes link also provides an opinion as to the mechanical advantage or barbed or raised fittings. It's written by an A&P mechanic, Designated Airworthiness Representative (DAR), and was a member of the EAA Homebuilt Aircraft Council so I'd rate this advice above the general run of the mill fluff.

[Ian]

Out of curiosity were you using avgas or mogas in when you were seeing the empty fuel filter. Avgas has a lower vapour pressure than mogas which may have contributed to the vapour issue. While the engine continued to run this is vapour issue is a bad thing. Most modern vehicles use submerged fuel pumps which solves the issues by creating positive pressure, only on flying dinosaurs does it remain an issue. For those interested in wikipedia has a good vapour lock article.

While Lycoming has come to the mogas party in recent years issuing the following service instruction the mechanical injectors and the associated heat creates a significantly higher vapour lock risk. In tank pumps would resolve this issue and have the potential to make aircraft more reliable, especially when using non-aviation fuels.

[skippydiesel]

32 minutes ago, Ian said:

I won't comment from a push fit perspective however when used with a clamp a barbed or raised fitting does provided a significant mechanical advantage and added safety, you can also buy aviation clamps with safety wire holes which should give you an extra feeling of safety if you've ever had a fuel hose come loose.

The following kitplanes link also provides an opinion as to the mechanical advantage or barbed or raised fittings. It's written by an A&P mechanic, Designated Airworthiness Representative (DAR), and was a member of the EAA Homebuilt Aircraft Council so I'd rate this advice above the general run of the mill fluff.

Raised collar -  by far the best system for push fit hoses.

 

Smooth fitting - perfectly acceptable when installed correctly.

 

Barb type - basically a visual marketing gimmick that does not improve sealing (may actually make it worse) , may enhance security/"mechanical advantage" (coming/pulling off) and can damage the internal lining of the hose causing particles to enter the fuel stream.

 

The Kitpanes article is promoting certified or certified like fittings - great if you need/want this complexity. The short paragraph on push fittings does little to add to the body of knowledge in this area. Understandably, A&P /LAIM  mechanics will always lean towards certified type & aviation tried solutions. This does not in any way diminish the effectiveness of automotive applications to aviation, where a modicum of mechanical logic is applied.

 

A push type hose fitting is simple, light & effective, when treated with basic mechanical logic:

 

Hoses must be:

 

As near as possible to the correct ID for the intended fitting OD. This will ensure a good seal, without the need for clamping (should still use a clamp).

Cut to precise length, so as not to have tension, that may cause the hose to slip/drift off the fitting. Where a hose must "span" between a relativly fixed fitting, to a moving one, (eg firewall to engine) the hose should be of sufficient length so as not to have tension applied and is best located in parallel or as close as is practical to the moving surface.

Hose & fitting must be well supported, to reduce movement, which can work to remove hose from fitting.

Of a quality that will not react adversely with the fuel/oil/coolant type and retain its flexibility/elasticity for the anticipated service life.

Not be used where high pressures are anticipated. With the exception of hydraulic brakes, this is a very unlikely situation in RAA class aircraft.

Replaced at the recommended service interval. The use of expensive substitutes (eg silicon)  to quality "rubber" hoses, of unknown in service characteristics and often greater weight, is more of a hanger talking point than a practical & economic decision. 

 

Clamps;

 

Should be of the fuel injector type - that is having a smooth inner surface & edges and a design that promotes 360 degree equal pressure.

Within the correct size range for the hose.

Only tightened so as to retain the hose (mechanical security) on the fitting 

Are a security/retaining device and should not be used to force a hose not to leak (get the right sized hose for the job).

Many adherents to the barbed fitting, use the clamp to seal the hose against the barb - false logic that may work in the short term but will almost certainly damage the hose internally making successful refitting (should this be required) a doubtful prospect.

May be reused many times IF not subject to damaging tightening forces.

 

Fittings;

 

This subject has already been well debated.

 

My position is, the old multi barbed style fittings (much loved by many) are now obsolete and should not be used where a smooth or raised collar type can be substituted. The automotive industry moved away from the barbed fitting many many years ago for good practical reasons.

 

[Ian]

I think that the key point is that push/friction fittings are most suitable on vacuum lines or where some other mechanism enforces integrity. When a greater degree of assurance is required, use a raised fitting with a clamp. Most automotive fittings use some form of clamping mechanism combined with a raised fitting simply for reliability. It probably makes sense to do the same on an airplane.

The article specifically states that "Not every hose offered by an aviation parts supplier will satisfy all of these criteria for any particular application. Also, your search for suitable hoses and fittings need not be restricted to aviation vendors." they're not promoting aviation parts however they are asking you to think about the compromises you make when selecting a part.

The fuel system is a critical system and you may want to take some degree of additional risk mitigation compared to system which you would use to attach to a vacuum line.

I am somewhat sympathetic to your view in relation to the mult-barbed fittings however where a single barb provides an area of greater diameter also allowing the attachment of a clamp its simply better from an engineering perspective.

The automotive industry moved away from push on fittings without a mechanical retainer on fluid and electrical connectors decades ago.

 

 

 

[skippydiesel]

Hi Ian,  All sales people will offer commentary/opinion based on A Risk (to them) minimisation B Greatest financial gain and then suggest, in some subtle/unsubtle way, that the choice is of course yours. This is pretty much what the Kitplanes article is doing. Those who are uncertain, conservative (disinclined to accept change) or keen to have bragging rights (the over the top expenditure types) will fall for this every time.

 

The reality is, push hose fittings (fuel/oil/coolant/vacuum) have been around pretty much for ever. The design of the male fitting has matured away from traditional multi barbs to either a single raised collar or just a plain pipe. I have been using this system on my little aircraft for about 10 years now (true miniscule compared with the 100 + years of powered flight) with no issues what so ever. Its cheap, light, secure (when properly fitted), causes me no anxiety. The only down side ,as far as I am concerned, is its poor visual appeal.

 

"The automotive industry moved away from push on fittings without a mechanical retainer on fluid and electrical connectors decades ago." - I was unaware that they ever used hoses without clamps of some sort (even if its just a twist of fencing wire). I do not advocate not using clamps, only that they should not be the mechanism that provides the  seal. Many people incorrectly view the clamp as the sealing mechanism, when it should be a good fit/match between hose ID & fitting OD with the clamp providing security.

 

We all have our comfort zone/limits -If you were to purchase my aircraft new, it would come with the latest automotive spring type clamps (just like my Ford Ranger) - I draw the line at this point - give me any one of the variose , injector style, screw clamps available.