Re fuelling

[benjam]

Afternoon all.

 

I am planning the ferry of my newly purchased aircraft. Although experienced in the aviation industry, I am an inexperienced LSA pilot.

 

I have some questions for the experts.

 

Mixing Mogas and Avgas. It seems that it achievable, but the Rotax guide says Avgas 100LL is not suitable. Is this what other operators have found? Do country strips have a Mogas capability these days? The ERSA would suggest not.

 

Do others just fill up their Rotax 912 ULS aircraft with Avgas and head off? if yes, any downsides to this practise? Or do I just change the oil after the 12-13 hour ferry?

 

Cheers

 

Ben

 

 

[Nightmare]

I guess you are doing this already, or planning to do so, but ERSA lists the aerodromes phone numbers, I'd call them to see what your options are at that location. They may be able to arrange something for you, if they don't stock it.

 

I'm keen to see some of the replies to your thread, as I am also in the market to purchase a plane.

 

I heard somewhere that if you do use AVGAS on such an engine, it may be an idea to do your services every 25hrs instead of 50hrs, something about your oil consumption going up when you

 

Tony.

 

 

[planesmaker]

No problems running rotax on avgas for what you are planning. Rotax recommend oil change every 25 when using avgas

 

 

[benjam]

No problems running rotax on avgas for what you are planning. Rotax recommend oil change every 25 when using avgas

So the Avgas 100LL will work with no drama? Are there a variety of avgas Lead levels out there?

 

 

[benjam]

Thanks Tony,

 

I see you are flying a Lightwing GR 912. Same as the one I am ferrying.

 

 

[Nightmare]

Hey Ben

 

A nose wheel version? Yes, they are a great aircraft to fly. I'd love to continue to fly it, but it looks like I may have a similar job to do next week if I take the plunge and purchase my first plane. Only a 6 hour flight for me if I go ahead with it.

 

Where are you ferrying it from/to?

 

Tony

 

 

[benjam]

No I have bought a TW version. Port Lincoln to Bris.

 

2 days, 1000nm, and about 12 hours flying is what I am expecting.

 

 

[Nightmare]

Where are you hangaring?

 

For your information, John at Coominya Flight Training (YBCM) operates a few Lightwings for flight training and private hire. He taught me to fly and he is very knowledgeable about the Lightwings.

 

 

[benjam]

Hangar at YCAB.

 

Good to know about Coominya.

 

Cheers

 

 

[dsam]

Ben, My Eurofox has a 912 ULS. For my local flights I use fresh Shell 98 Mogas. For cross country trips, convenience & availability usually dictates 100LL Avgas, particularly for interim refuelling stops.

 

For overnight stays, I consider using my two 20 litre fold-up rubber jerry "cans" and toting them back next morning with fresh premium unleaded if I can source it wherever I've overnighted.

 

20 Litre Collapsible Jerry Can - Liquid Containment Bladders & Liners – Fuel, Water, Petrol, Diesel, Water Storage

 

I fill these rubber bladders through a special filter funnel (Mr. Funnel) that separates out any water (and other particulates) that may be in the outback mogas source: (Buy Online)

 

As planesmaker mentioned, keep track of each fuel type you consume. If you find that your percentage of Avgas vs mogas used is > 50%, change your oil twice as frequently. My understanding is that the lead in Avgas can accumulate in the reduction gear & clutch areas of the Rotax, and cause problems.

 

I'm not an expert, so others on this forum can probably speak with more authority and experience, but this practice has served me well so far. Rotax documentation should be your primary source of info for this matter concerning Avgas & oil change frequency.

 

I am a fan of phoning ahead to aerodrome operators confirming fuel availability, and carnet card types required. Pumps often are out of order.

 

When planning an overnight stop, I usually ask the motel operators whether Premium unleaded is available in town, too.

 

 

[Downunder]

Any mix of 100% avgas to 100% 98/95 mogas (80hp will take 91) will run fine. It just means more services.

 

My aircraft was ferried east to west on avgas. As I prefer to run on 98 (cleaner/cheaper), I did an oil & filter change after the ferry trip.

 

Remember to clean out the oil canister too. The grey lead will line the bottom.

 

 

[skippydiesel]

DSAM's policy is almost identical to mine.

 

I have run my 912 ULS on 95 RON (Rotax min spec) without any apparent change in performance. I hope that by using 98 RON I am accommodating any loss of RON during storage (fuel station/home). I rarely use AVGAS but again have done so without any apparent change in performance.

 

I would council against only filtering (Mr Funnel) into your transport container (jerrycan or bladder). I always filter into the aircraft as the penultimate contamination catch point (the ultimate being the in aircraft filters). Containers may potentially have condensation, breakdown in the container material, paint, rust, etc that will be transferred with the fuel . So best to filter into the aircraft.

 

Like DSAM I find out, ahead of time, where I can get 98 RON along my track. You can use BP/Shell/Caltex apps , local aeroclub, etc for rout planning/fuel supply So fare have had no problems.

 

The lead in AVGAS contaminates/builds up on all internal all parts of the 912 engine and gear box not just the gearbox/sprag clutch. Not only due you have to halve the oil change interval but also reduce the service life of the gearbox/clutch (from memory 600hrs a disassembly, clean, inspection is required)

 

 

[dsam]

Skippydiesel, I note your concerns on filtering into the aircraft, rather than the foldable fuel bladders, and your reasoning is worthy of support, particularly for a low wing aircraft.

 

I have made a deliberate choice to do it my way for a few reasons. Firstly, my aircraft is a high wing, and managing a small stool, funnel, and flexible fuel bladder is a high-wire act fraught with incident (big spills onto plexiglas, inability to see when tank nears full, longer time pouring fuel, stumbles & fumbles at a windy, rainy, dusty, exposed outback aerodrome). Much easier and safer to funnel into a bladder at my feet, under shelter in a petrol station IMHO.

 

Are you saying you filter both into your fuel bladder, AND the aircraft? If so, have you considered the high volatility of Premium mogas? In a sealed container, the esters stay in solution, but slow pouring through a funnel (twice) would see a portion of these evaporate, lowering its effective RON. When I'm at home, I deliberately chose a petrol station with high turnover, on the assumption that their premium fuel is as fresh as I can get it, for the same RON reason.

 

My fuel bladders are new, and only ever used for my flying activities, so I have confidence in their integrity (I'm happy to hear otherwise). Being collapsible, and remaining sealed and flat, there is very little air within them for moisture to develop, I would think. Of course I always pre-flight including a bottom tank drain/inspection for water.

 

I do my annual maintenance with a LAME, and over the last 5 years, I can report that my fuel filter shows no adverse effects from my refuelling protocol. Long may that continue...

 

Dave

 

 

[facthunter]

Using it occasionally is generally considered a practical approach but because the Rotax has liquid cooled heads it runs much cooler than the aircooled motors the 100LL was designed for, and occasionally there is a build up of deposits on the valve seats. This can end up uneven if one bit detaches and cause leaking under high pressure and compression loss. Usually running more mogas through the motor corrects it in a short time, but there could be instances of seat damage being done in the meantime. Monitor your compressions when burping the engine would be what I'd do. No need to do a compression test unless it feels bad, and usually it will only be on one cylinder and you can compare one to the others. Mixing fuels just dilutes the % of lead additive, reducing the effect. The valves in a 912 don't give much trouble generally, but I certainly wouldn't run100% leaded fuel for a long period. Nev

 

 

[skippydiesel]

DSM - As vertically challenged person, I sympathise with the difficulties in refuelling your high wing aircraft. Believe me even my low wing has problems (design fixed in later models) resulting in occasional spilt/wasted fuel (spoiling my careful measuring) steaks down wing/fuselage and aromatic trousers/shoes.

 

I only filter once - into the aircraft (not counting the on board filtration).

 

I agree with your logic, in your circumstances, regarding the dedicated collapsible jerrycans and your compromise system due to high wing fuelling points.

 

I have modified, by adding an internal filter (diesel mesh type) & a hook, to an off the shelf funnel that boasts a top & bottom screw cap. My mods include a way of holding the funnel secure & vertical. Unfortunately the speed at which the funnel drains is slightly reduced by the addition of the filter.

 

The added time to fill, causes muscle fatigue, which conspires with the "floppiness" of the collapsing jerrycan, to sometimes induce the shakes, leading to spillage.

 

I am continually amazed by the very small but consistent amount of material (gratifyingly) caught by the filter.

 

At home (base) I have a 12 volt pump to do the "heavy" lifting, so no spillage. I could carry a small electric fuel pump but the added weight and drain on my battery may not be such a good idea. Something to consider in my dotage.

 

Despite the problems, I have piece of mind knowing that the fuel going into the tank is as clean as I can, practically, get it.

 

I still inspect my filters at 50 hrs & replace at 200 hrs (even if they look clean)

 

 

[benjam]

Thanks all for the advice. It is well received.

 

Do you need to filter the avgas when filling at an airport? Or are you only filtering Mogas into/out of your jerry cans?

 

 

[dsam]

Thanks all for the advice. It is well received.Do you need to filter the avgas when filling at an airport? Or are you only filtering Mogas into/out of your jerry cans?

In my case, I don't filter the Avgas from a bowser as there are supposed to be standards adhered to on storage. Petrol stations are more of an unknown quantity so that's why I filter Mogas.

Avgas from drum storage can be more subject to problems, so perhaps it would be wise to filter Avgas stored in this way.

 

 

[Downunder]

Can't say I've ever seen someone filter avgas from a (approved installation) bowser as dsam says...

 

A "mr funnel" or similar should be used with mogas. They are said to be able to remove water from fuel but I'm a bit suspect on that.

 

Removing particles is good enough for me.

 

Buy Online

 

 

[skippydiesel]

I suspect all fuel. from whatever source.

 

Contamination is unavoidable:

 

• Condensation - water
   
   
  
• Corrosion - rust
   
   
  
• Algi
   
   
  
• Brake down of "rubber" hoses, "o"rings, seals & pump diaphragms etc
   
   
  
• Paint flakes
   
   
  
• Metal swarf
   
   
  
• Plastic chips, fibres, etc
   
   
  
• Windblown chaff, dust
   
   
  
• Insects
   
   
  
• Other hydrocarbons
   
   
  
• Etc.
   
   
  

 

 

The best way to minimise (note I did not say total removal) these contaminants is to filter the fuel into the aircraft.

 

Aviation bowser's have a filter on the delivery side. Unfortunately it is "up stream" from a long rubber hose and an uncapped delivery gun/nozzle.

 

The more times fuel is decanted the more chance of contamination.

 

It is probably completely "anal" but it gives me "piece of mind" to filter the fuel into the aircraft tanks.

 

I would rather the on board fuel filtration be underutilised than relied on as the last line of defence.

 

Check your aircraft fuel filters every 50 hrs without fail.

 

One last thing you can easily make your own version of a Mr Funnel for a lot less $$$$

 

 

[benjam]

One last thing you can easily make your own version of a Mr Funnel for a lot less $$$$

Too Late. I bought one last night on line.

 

 

[rossrynehart]

I have regularly mixed Avgas with unleaded 95 and 98 on long cross country trips outback when 95 and 98is not available. You can look up the mixing rations on line to that are needed to maintain the RON recommended by Rotax. Its roughly 50/50. Also us Declin additive when using Avgas - scavengers the lead.

 

 

[skippydiesel]

Hi Rossyehart,

 

My understanding is; Rotax specifications allow for fuel from 95 RON or higher, including AVGAS. I effect this means you can run on straight 95 or 98 RON and AVGAS or blend of any two or three..

 

There is no need to be concerned about ratios/blends.

 

In real situations, you will have a blend of varying ratios, depending on the amount of fuel remaining in the aircraft tank and the RON standard and amount of fuel added.

 

The Rotax 912's ability to generate take-off and cruise power will be unaffected.

 

In theory there may be a small performance benefit from using higher RON fuels however few pilots report any noticeable change.

 

There are opinions "out there" that suggest that the lower volatility of AVGAS will improve the hot starting of the engine, due to reduced incidence of "vapour lock" .

 

The tendency of 912's to develop vapour lock on hot days, can be "managed" by various strategies.

 

It is well documented that the regular use of AVGAS will result in the build up of lead deposits on internal components of the engine & gear box, necessitating more frequent oil changes and an early gear box strip, inspection & clean.

 

I would not be relying on any additive to "scavenge the lead" much better to keep the use of AVGAS to the barest minimum or adopt the Rotax service regime for using AVGAS.

 

 

[OZJohn]

Rotax recommends maximum of 30% Avgas. Oil changes and gearbox service requirements as above. Lead affects the gearbox clutch.

 

 

[rossrynehart]

HI Skippy Diesel,

 

Yes, I agree - my mistake - I meant to say that I mix ordinary unleaded with Avgas when premium ( 95or 98) is not available.

 

As for the Declin scavenger - I adopted that practice after flying the US where it is widely used with Avgas and rotax engines. I also change oil at 25 hrs irrespective.

 

chers

 

r

 

 

[nwarthmann]

For overnight stays, I consider using my two 20 litre fold-up rubber jerry "cans" and toting them back next morning with fresh premium unleaded if I can source it wherever I've overnighted.

20 Litre Collapsible Jerry Can - Liquid Containment Bladders & Liners – Fuel, Water, Petrol, Diesel, Water Storage

 

I fill these rubber bladders through a special filter funnel (Mr. Funnel) that separates out any water (and other particulates) that may be in the outback mogas source: (Buy Online)

Hi there, I am using these exact same jerry cans, but I've found that mine are not seal. They leak when laid on their sides, or when weight is pressing on them. Very annoying. Is it the same with yours and have I just gotten a bad batch?