Rotax 912 80hp Is the gascolator on my airplane enough of a fuel filter

Hi Michael,

Earl's Performance Inline Fuel Filters

I agree with your concern about sintered bronze filter medium.

I would also point out ;

The old fashioned multi barb spigot hose connection - these days a definite no no!

Inspection will require dismantling the casing - No quick preflight check, Fuel spill - Nasty!

Leak prevention/risk is dependent on no less than two compression fittings - Unnecessary risk compared with a transparent plastic casing.

Weight - why add it, when a plastic one will be so much lighter?

There is a glass barrel equivalent of the above with gauze filter medium - I have 2 possibly 3 unused ones. If you like I will post them to you at your cost (from NSW Australia)😈

FWIW, my certificated motorglider has only a nylon coarse mesh filter in the tanks on the fuel pickup and a gascolator on the firewall, not at a low point. The best approach is to not let crap get into the fuel in the first place. Unless coming from a 100LL pump with a maintained final filter, nothing goes into my tanks from something like gas cans without being filtered on the way.

Adding some off-some-shelf filter to the fuel line can add hazards rather than reduce them. My ship for example has entirely solid fuel lines until going into the engine compartment. There, the hoses are all fire-sleeved, aircraft grade with AN fittings. Cutting into a tube or hose and securing a filter with hose clamps is asking for trouble, imo, though I see such things in experimental and LSA's all the time.

Also, a filter that is too good is bad; it can stop and eventually clog with particles so small that they would cause no engine issues anyway.

Hi Jeffry,

 ".............nylon coarse mesh filter in the tanks"

This idea of having a coarse filter in the tank(s) is way out of date. If good fuel filling "hygiene" is being practised ie filter funnel, there should be no need for your, hard to service, in tank strainer (thats pretty much what they are) - its redundant.

If you are extra cautious, as I am, an inline gauze filter on each supply line (as previously recommended), located in an easy to see/check /service position, will be far more effective, than an unseen, hard to service/check, in tank finger strainer. 

"Adding some off-some-shelf filter to the fuel line can add hazards rather than reduce them."

You clearly do not understand what is available "off the shelf".  Rotax recomend a fine filter, 70-100Mu (0.01mm). In line filters, meeting the Rotax standard, are available, at low cost, from reputable maker/ suppliers like Baldwin & Hengst. This style of filter is in widespread use, particularly in aircraft of European origin - they have proven to be reliable & effective. All the more so as many of these aircraft are using automotive petrol (ULP) that does not have to meet the same high standard of "cleanliness" as AvGas.

My ship for example has entirely solid fuel lines until going into the engine compartment."

Bravo! Your aircraft is Certified - it's likly that this type of fuel reticulation system is required for Certification. Recreation level aircraft (for the most part not Certified) have now been flying for what 30-40 years, with "rubber" ' combination metal pipe & rubber, as well as full metal pipe, to engine compartment - to my knowledge no problems (subject to appropriate installation/maintenance). 

"Also, a filter that is too good is bad; it can stop and eventually clog with particles so small that they would cause no engine issues anyway."

Installing finer filters than recommended, achieves nothing practical, being both a waste of money, reduces inservice life expectancy and increases risk of fuel starvation.

Fuel Filter Selection

Is a compromise between removal of unwanted contaminants (particles). flow (supply) and  projected in service life.

The removal of contaminants is a factor of aperture/pore size.

Flow restriction will be influenced by aperture/pore size and the area of the filter media.

In service life will be dictated by degree of contamination, aperture/pore size and the area of the filter media.

Fuel filters catch unwanted particles AND reduce fuel flow. As their time in service increases both filtration and restriction of flow increases. All effective filters will eventually "clog" if left in service for too long.

Alway go with the manufactures (Rotax) recommended filtration specifications - they have crunched the numbers, taking all of the above into consideraton.

Mitigating risk is always a compromise.  The designer/owner of the aircraft will take into consideration, often conflicting, matters such as:

Likelihood of failure (Risk) - Design, standards of construction, quality of materials.

Cost effectiveness - How do the available systems/products stack against each other. 

Servisabity  -  Frequency (Daily, ? Hours, Annual, Longer)

Durability - Service life to replacement.

Weight - Should always be a factor in aircraft component selection. 

Complexity - Is the proposed system adding to or reducing complexity. It is usually accepted that an increase in complexity also increase the chance of failure.  

Etc

Your aircraft is Certified - Certification usually implies adherence to a range of safety standards, applying to a number of diffrent aircraft types. Certification, by a third party (Government authority) is usually strongly influenced by a wish to avoid responsibility/litigation (cover thine arse) approach to safety ie over the top.   

Recreational aircraft rarely have to meet such a high (costly) standards - risk (increased?) being accepted by pilot & passengers. I do not recall a recreation level aircraft incident, where a well installed/maintained, non certified, fuel system was the cause. 

Compare weight, servisabity, filter media area & cost of a Baldwin BF7850  with a standard Gascolator.

Something like this for a metal re-usable fuel filter.

https://s7ns-noise.com/products/fuel-filter-pingel-inline-for-5-16-chrome?variant=39658916249733

https://s7ns-noise.com/products/fuel-filter-pingel-6an?_pos=1&_sid=cf79e949a&_ss=r

https://www.amazon.com/Motorcycle-CocoMocart-Universal-Gasoline-Motorcycles/dp/B09YLTKVGR/ref=sr_1_25?crid=3GWPZBLMQVU1K&dib=eyJ2IjoiMSJ9.JOtSegAHUKt2jnm8XRSjUetAc6utHqnyWGYPrM1tQfGF4hw5X4Z2LtTaxv6jGnoxyWxG-2f3Sp3YejFNNaQ_feIXNXSrhfwB7329VKysPZDpKt9rmPWJEB_HCvLmze6CVb_Emqd0qkroh2B4Vxb0jFk9jqFUG7jJPwV4ooOO-ga2KhMCaaSt-qP09gDLZ-JC.0Me1XMj8vpiouQVm0tF6eQ7SrQSkcL1VZZt-COUaU00&dib_tag=se&keywords=metal%2Bfuel%2Bfilter&qid=1725113613&sprefix=metal%2Bfuel%2Bfilter%2Caps%2C174&sr=8-25&th=1

https://www.amazon.com/Edelbrock-8157-Street-Filter-Aluminum/dp/B01D30860E/ref=sr_1_45?crid=3GWPZBLMQVU1K&dib=eyJ2IjoiMSJ9.RPpUuyLeQmWAOjkWJ3UEUNOwjyw3zDzA8dXLqENeMnyNkb6tlKCAu_RRnKpcM568WOQy5SNZXwBPZSRKFclUc_X_EKkcMVbO7mrNQBHx9OCgabHspzNeY8OPByKiT4w7p32UKMEZLUoRZZNYzWIySpSKRXz3ty817fRgNta713gV-mGTGQHxNKtrtqeZxWZS.8PHS69YgIeSE8f-gQFF73ExRFfv8tiVYbm7Mmn1l4YE&dib_tag=se&keywords=metal+fuel+filter&qid=1725113629&sprefix=metal+fuel+filter%2Caps%2C174&sr=8-45

Shortened comment for the OP: Yes, "just" a gascolator is fine. That, with a course tank filter, is used in countless certificated aircraft.

Roger, yes, I know what off the shelf means. Some good stuff and countless crap stuff. Can the average Joe, or even the above average Joe, know the difference? Perhaps the LSA manufacturers know better, in which case replace the installed filter with the exact one which came with the airplane. (Which is all you're allowed to do anyway. Experimental, you can legally do anything. With LSA, any and every change is required to have approval from the manufacturer, and that would certainly include adding a filter that wasn't previously there. Not that I entirely trust them either. For example, on a certain gyroplane, the passenger essentially sits on the fuel tank. This had a "sight glass" for fuel level - a 90 deg fitting on the bottom and a plastic tube leading to a 90 deg fitting on the top. With nothing protecting it from a misplacement of the passenger's foot. Has it killed anyone yet? Well, maybe; there wasn't enough left after the fire to know. (Yet another instructor in my logbook who is now dead).

Fuel system problems are a leading cause of accidents with homebuilts and sport aircraft in general, which is why the EAA is putting a special emphasis on them. But though categorized differently, fire is particularly fatal. I've had two engine fires. Though relatively minor, their minority status in part came from the old "antiquated" rules for certificated a/c: AN fittings, metal lines and such. No way, no how would I ever stick a plastic bodied fuel filter in the engine compartment, which is where they often seem to be. Nor anywhere else (see above). 

"Properly installed and maintained", yeah okay, pretty much a universal thing. Rubber hose clamped to metal pipe? IDK how many times I've seen leaks at such joints. One could say old hose or improper tightening or re-tightening, I guess. But how many times have I found leaks at AN fittings? Hardly ever, and only on initial assembly. Tighten properly once, and they stay tightened. Unlike hoses.

IMO, fuel systems, don't cheap out, AC43-13b isn't stupid, and treat gasoline like a lit stick of dynamite. A friend didn't. Tried to start a truck with issues poured a little gas in the manifold. Was leaning under the hood when another friend hit the starter. The backfire blew the gas back on him. Burned maybe 5 seconds. Took off half his face, one eye and made one arm nearly useless. Plastic in-line filters with hose clamps. Nope. I don't care how many others get away with it. Just nope, not me.