Re: Rotax 912 80hp Is the gascolator on my airplane enough of a fuel filter
by Sean Griffin » 6 days ago
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)😈
Re: Rotax 912 80hp Is the gascolator on my airplane enough of a fuel filter
by Jeffry Stetson » Yesterday
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.
Re: Rotax 912 80hp Is the gascolator on my airplane enough of a fuel filter
by Sean Griffin » 22 hours ago
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This idea of having a coarse filter in the tank(s) is way out of date.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.
Re: Rotax 912 80hp Is the gascolator on my airplane enough of a fuel filter
by Roger Lee » 11 hours ago
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
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
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