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Vapor Lock RV-12 Rotax 912ULS

Job is continuing... Today I wrapped right carb fuel line and output line from mechanical pump. Everything FWF is going to have two wraps of foil-backed fiberglass insulation including return line to tank and fuel pressure hose. I may even insulate side of oil tank nearest the right carburetor. For now, mechanical pump will remain uninsulated – pump is near cowling front air inlet.

First photo shows single wrap of insulation and second photo shows completion with both wraps applied.
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It will be interesting to note your results...

I assume you've retained some prime winter grade Mogas purchased from the local Costco sometime during the winter months?
 
It will be interesting to note your results...

I assume you've retained some prime winter grade Mogas purchased from the local Costco sometime during the winter months?

(I'm gonna sound a little preachy here...)

Don't. At least not for flying. Using that fuel - even with the added insulation in the photos - would be a big, big mistake in warmer/hot weather. Wintertime auto fuel that is blended for cold winter air has a vapor pressure high enough to cause it to boil/gas off even in higher ambient temperatures, potentially such as when sitting in a gas tank on a hot day exposed to the sun, etc. The solution for high vapor pressure fuels that boil/vapor lock when hot is to change to a fuel that is safe in the environment in which you are operating.

Use fuel intended for the current climate. If your fuel is not appropriate to the environment, drain it and replace it. Put it in your lawn mower and burn it there. Don't ever (read: EVER) use fuel blended for cold weather in hot ambient environments in an airplane. You're just playing with/tempting fate if you do. It's basic physics.

Also, opening the oil door upon shut down helps to limit heat soaking of the engine.

And, I'll point out that the following cautions and warnings appear in the RV-12 POH:

NOTE
To prevent vapor building in the carburetor after shutdown on hot days, the oil door should be left open to let heat out of the cowl. Leaving the canopy in the open position latched with the F-1231G Canopy Catch, will reduce the risk of vapor-lock. (pg. 4-15)

and

CAUTION
Use of poor quality fuel or winter blend fuels in hot conditions may result in vapor lock. (pg. 8-3)

and

WARNING
During high ambient temperature conditions, run the fuel pump for 5 mins to flush the fuel lines and minimize the potential for vapor lock (pg. 4-2)​

Stay safe. We publish these items because they are important operational parameters to follow to help ensure the safe operation of the aircraft.
 
I’m going to sound a little anal here… My intention is to reduce the chance of Vapor Lock regardless of fuel used or ambient conditions. I will insulate fuel components FWF to reduce risk of heat soak. I will also monitor Fuel Pressure and Fuel Flow during take-off phase of flight going forward. I am adding temp sensing for under-cowl and fuel line where it T’s to both carburetors. Also installing the higher pressure (4.5-6 psig) FAC-40135 Facet Fuel Pump per Van’s Notification 18-07-12. Regardless of flying season, ground ops will be minimized. No more repeated landings to full stop with taxi back. Instead, landings will be practiced with touch/go to maintain cooling. Oil door has been, and will continue to be, opened with engine stop. I may add a cooling fan at the open oil door to extract heat.

I had a problem with Vapor Lock that I don’t want to experience again. I am not 100% certain that using the “correct” selection of fuel blend will guarantee no Vapor Lock under the severe conditions that aircraft engines are asked to perform.
 
I’m going to sound a little anal here… My intention is to reduce the chance of Vapor Lock regardless of fuel used or ambient conditions. I will insulate fuel components FWF to reduce risk of heat soak. I will also monitor Fuel Pressure and Fuel Flow during take-off phase of flight going forward. I am adding temp sensing for under-cowl and fuel line where it T’s to both carburetors. Also installing the higher pressure (4.5-6 psig) FAC-40135 Facet Fuel Pump per Van’s Notification 18-07-12. Regardless of flying season, ground ops will be minimized. No more repeated landings to full stop with taxi back. Instead, landings will be practiced with touch/go to maintain cooling. Oil door has been, and will continue to be, opened with engine stop. I may add a cooling fan at the open oil door to extract heat.

I had a problem with Vapor Lock that I don’t want to experience again. I am not 100% certain that using the “correct” selection of fuel blend will guarantee no Vapor Lock under the severe conditions that aircraft engines are asked to perform.

I hear ya, and understand your approach to further mitigate. My reaction was specifically to the idea of retaining/using cold weather fuel, even for test purposes, in a hot weather environment (or, more specifically in any environment other than the cold weather). That sort of testing should be reserved for a safe and open (read: not an airport ... more open and safe than that) test location and executed by someone with enough experience to handle expected and unexpected emergencies.
 
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A question for the Rotax experts: Is the 912iS, with its totally different fuel system, more or less likely to experience vapor lock problems on takeoff or in flight than the 912 ULS?

Thanks!
 
A question for the Rotax experts: Is the 912iS, with its totally different fuel system, more or less likely to experience vapor lock problems on takeoff or in flight than the 912 ULS?

Thanks!

Much less likely to experience vapor lock because the fuel pressure is so much higher.
 
A question for the Rotax experts: Is the 912iS, with its totally different fuel system, more or less likely to experience vapor lock problems on takeoff or in flight than the 912 ULS?

Thanks!

As John said, higher fuel pressure helps prevent vaporization.. and the fuel is constantly circulated from the tank, through the pumps, to the engine.. and whatever is not used by the engine (which is most of it), is returned back to the tank.
 
As John said, higher fuel pressure helps prevent vaporization.. and the fuel is constantly circulated from the tank, through the pumps, to the engine.. and whatever is not used by the engine (which is most of it), is returned back to the tank.

Unless and until the fuel is boiling/vaporizing before it has a chance to reach and be pressurized at the pump, of course. Very cold weather fuel in a hot fuel tank could also be a problem before the pump gets involved. Just pointing out the multiple parts of the system to think about here.
 
I finished installing foil-backed fiberglass insulation on fuel lines. Each line has two wraps. I decided to hold up on return-to-tank and fuel pressure lines for now.

I will flight test and start recording data over the weekend...
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Unless and until the fuel is boiling/vaporizing before it has a chance to reach and be pressurized at the pump, of course.

The only point the fuel is not under pressure is in the tank. The head pressure in the tank pressurizes it the short distance to the electric pump which pressurizes it to the mechanical pump. Am I missing something?
 
I finished installing foil-backed fiberglass insulation on fuel lines. Each line has two wraps. I decided to hold up on return-to-tank and fuel pressure lines for now.

I will flight test and start recording data over the weekend...
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What is your baseline to know if you have made a difference?
 
What is your baseline to know if you have made a difference?

The only baseline I have is temperature readings on a single flight listed in post #59 and, 650 hours prior flight time with no incidence of Vapor Lock.

This is not exactly Jet Propulsion Laboratory at California Institute of Technology. Just earlier this week a spent an hour studying privy vents thanks to Tony T...
 
It would be interesting to see how much net positive suction head there is from tank level at fuel temps of 110F like we routinely see here in Phoenix summers. Even on those days I find turning on my electric pump clears up the hi fuel flow and lo fuel pressure alarms quickly.
 
First flight after installing foil-backed fiberglass insulation on fuel lines FWF and permanent install of 2-channel temp sensor.

One hour flight to three outlying airports with 57 OAT. Fuel temp was 66F at completion of engine warm-up prior to first take-off. Fuel temp stabilized in cruise flight on first leg at 83F and highest fuel temp was ground ops at 90F. I decided to do full-stop landings with taxi back to check temps.

Can’t say a whole lot more until OAT become summer…
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Not to hijack the vapor lock discussion, but this accident is relevant. Vapor lock or not, I was struck by the PIC’s decision to turn back given his altitude and the proximity of a road virtually paralleling the extended center line of the runway. I’m not second guessing, the pilot was highly experienced. My point is this, establishing a decision altitude is important. The extremely remote possibility of vapor lock is just another of many reasons to do so.

https://app.ntsb.gov/pdfgenerator/R...D=20181117X94409&AKey=1&RType=Prelim&IType=FA

NTSB Docket Number ERA19FA048
 
Two vapor lock incidents on the same day, with the same plane on a 59 degree day?

Lots of unanswered questions..

Was the plane left outside, canopy closed and sun shining down on fuel tank?

Was something done during the 100 inspection that caused the problem?

Did the engine ever get torn down and inspected?

All this vapor lock talk is starting to make me uneasy with my plane now..
 
All this vapor lock talk is starting to make me uneasy with my plane now..

Maybe I’m naive, but it doesn’t worry me at all. Seems preventable by simply following Van’s recommendations in PoH. Run the fuel pump at all times and using appropriate fuels. A dab of 100LL to ‘spike’ your Mogas during the winter to summer gas transition months seems simple enough to me.

Of course I’ll feel differently if it happens to me, but I just don’t see a glut of RV12’s or any Rotax 912ULS planes for that manner falling out of sky due to vapor lock.
 
Considering the above plane was Van's SLSA #6, I would think an extensive investigation was conducted. Can anyone find a "final report"? This was a Florida aircraft, so I don't expect a winter mix gasoline was the issue. The accident report seemed to indicate "vapor lock" was a known issue with this plane, even before the day of the crash. It would be interesting if some other issue was found, rather than vapor lock. Everything I have read seems to indicate that it's not really a problem that is easy to reproduce, yet someone believed this plane had ongoing issues of vapor lock.. Really sad that someone died in a plane that had a known and ongoing issue with the motor not running right.. His user name was "hook" here on VAF.. :(

http://www.kathrynsreport.com/2018/11/vans-rv-12-n232va-fatal-accident.html?m=1

EDIT: Found the answer to my question... Final Report has been issued.. Unfortunately all they are reporting is "A partial loss of engine power during initial climb for undetermined reasons, and pilot's failure to maintain airspeed during a turn back to the runway, which resulted in an exceedance of the airplane's critical angle of attack, and subsequent aerodynamic stall." No record of any addition investigation conducted to determine the cause of the "partial loss of engine power"..

Interesting data pulled from the EFIS Memory.. https://data.ntsb.gov/Docket/Docume...t Data Specialist's Factual Report-Master.PDF

https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/98649/pdf

https://data.ntsb.gov/Docket?ProjectID=98649
 
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I've ben flying in Georgia and South Carolina during the summer months, never had a vapor lock issue using auto gas, although I've been adding 1oz of Seafoam to my gas to stabilize it incase I don't get to fly for a while...my only concern is keeping the oil temp out of caution range during summer....
 
Another data set from flight on Tuesday morning. The day actually got quite warm (80F) but winds late morning-on were gusting 28, so I flew early morning. Engine ran well with solid fuel flow and pressure in climbs.

OAT temp was 61-71F.

No conclusions can be drawn from data. Still anxious to see fuel line temp and under-cowl temps when weather gets really warm.
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Jim,

How are you instrumenting the fuel lines? I’m wondering if you are measuring engine compartment temps as opposed to fluid temperature which, given the insulating effect of the hose and fire sleeve, could be much lower than the outer wall temp of the hose and fire sleeve. My guess is the critical temp to measure is the tank temperature. I do find that after 45 min cruise at 8 or 9 thousand feet in Phoenix summer heat I can usually secure the electric pump in cruise without any indication of flashing in the fuel line. My vapor lock indications have always occurred during initial climb in the summer.

Rich
 
Considering the above plane was Van's SLSA #6, I would think an extensive investigation was conducted. Can anyone find a "final report"? This was a Florida aircraft, so I don't expect a winter mix gasoline was the issue. The accident report seemed to indicate "vapor lock" was a known issue with this plane, even before the day of the crash. It would be interesting if some other issue was found, rather than vapor lock. Everything I have read seems to indicate that it's not really a problem that is easy to reproduce, yet someone believed this plane had ongoing issues of vapor lock.. Really sad that someone died in a plane that had a known and ongoing issue with the motor not running right.. His user name was "hook" here on VAF.. :(

http://www.kathrynsreport.com/2018/11/vans-rv-12-n232va-fatal-accident.html?m=1

EDIT: Found the answer to my question... Final Report has been issued.. Unfortunately all they are reporting is "A partial loss of engine power during initial climb for undetermined reasons, and pilot's failure to maintain airspeed during a turn back to the runway, which resulted in an exceedance of the airplane's critical angle of attack, and subsequent aerodynamic stall." No record of any addition investigation conducted to determine the cause of the "partial loss of engine power"..

Interesting data pulled from the EFIS Memory.. https://data.ntsb.gov/Docket/Docume...t Data Specialist's Factual Report-Master.PDF

https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/98649/pdf

https://data.ntsb.gov/Docket?ProjectID=98649

That's an interesting find. Thanks for posting the details. I was not aware of this accident. I spent some time this morning going over the data log and reading the reports. As sometimes happens, I have to say I found the reports somewhat unsatisfying.

One would think that a loss of fuel flow or fuel pressure would have proceeded at least the temporary power loss or drop, but fuel PSI didn't drop below 4 as near as I can see, nor did fuel flow show much variation.

The loss of power is unsettling. The subsequent turn back and stall accident is tragic. It is also interesting to note that it was 2013 build and I wonder if it was due for a 5-year carb "overhaul". What caused this partial loss of power? Scrolling thru the CSV data file was also unsatisfying. The CFI witness statement was somewhat more illuminating. The NTSB allowed the mention of vapor lock in the history, and that the student pilot asked about the open cowling (oil door or whole cowling off?) More important was the mention of "sump" the fuel system to look for debris. No mention if they drained the fuel system and took apart the gascolator to look at the screen for debris, or removed the carb bowls to do the same (during the mx troubleshooting - the NTSB investigation stated the bowls were clean post-accident).

Van's can't say anything about this either separately I am sure first due to litigation and secondly because they are a NTSB "party" to the investigation and must adhere to confidentiality rules.

What I learned from this was to further emphasize respecting airspeed and to fly the airplane - airspeed first, altitude second, navigation 3rd. Easy to say as a monday morning quarterback of course.
 
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I don't know if anyone at NSTB weighed the floats from the carbs on that Rotax engine... might have been worth checking out.

If fuel pressure is good, steep angle of climb, as indicated by a 65 kt climb out speed, could indicate debris in float valve, or heavy floats, flooding the engine or causing it to run too rich, and loss of power.

Just one more thing that could have been looked into. I know of Kit Foxes that put large Alaskan Bushwheel tires on the front, and it causes problems for the Carbs on Rotax 912 engines, flooding, and fuel leaking out of the carbs, due to the high nose up attitude now of the plane on the ground while taxiing.
 
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That's an interesting find. Thanks for posting the details. I was not aware of this accident. I spent some time this morning going over the data log and reading the reports. As sometimes happens, I have to say I found the reports somewhat unsatisfying.

One would think that a loss of fuel flow or fuel pressure would have proceeded at least the temporary power loss or drop, but fuel PSI didn't drop below 4 as near as I can see, nor did fuel flow show much variation.

The loss of power is unsettling. The subsequent turn back and stall accident is tragic. It is also interesting to note that it was 2013 build and I wonder if it was due for a 5-year carb "overhaul". What caused this partial loss of power? Scrolling thru the CSV data file was also unsatisfying. The CFI witness statement was somewhat more illuminating. The NTSB allowed the mention of vapor lock in the history, and that the student pilot asked about the open cowling (oil door or whole cowling off?) More important was the mention of "sump" the fuel system to look for debris. No mention if they drained the fuel system and took apart the gascolator to look at the screen for debris, or removed the carb bowls to do the same (during the mx troubleshooting - the NTSB investigation stated the bowls were clean post-accident).

Van's can't say anything about this either separately I am sure first due to litigation and secondly because they are a NTSB "party" to the investigation and must adhere to confidentiality rules.

What I learned from this was to further emphasize respecting airspeed and to fly the airplane - airspeed first, altitude second, navigation 3rd. Easy to say as a monday morning quarterback of course.

Well unfortunately, I can't say that I know 100% what to expect with regard to EFIS data when vapor lock occurs. I don't know that fuel pressure or fuel flow would show a drop during vapor lock. Is it not still possible for there to be indicated fuel flow due to RETURN fuel flow during a vapor lock? I do think the low OAT makes me question if vapor lock actually occurred. From what I have read, typical vapor lock is hard to reliably re-create, and typically takes place with OAT above 80 degrees F, yet this airplane experienced partial loss of engine power on two successive flights in OATs cooler than 80 degrees. It's also hard to discount the fact that this incident occurred immediately after a 100 hr. inspection and engine heat soak clearly wan't a factor here either.

I haven't been able to reconcile in my mind why NTSB feels the pilot pulled back the throttle for three seconds while in a very steep turn back to the airport, while the stall horn was sounding and air speed was critically low. This was a very experienced ATP, CFI, pilot and I don't believe he would pull back the throttle right when he needed power the most. IMHO, he was trying his best to get back to the runway, right on the edge of stall, in a low altitude steep turn and then the engine had a huge power loss and almost immediate stall.

I lean towards believing there was a possible fuel blockage, carb issue or other engine issue that caused the power loss, but I'm not convinced it was vapor lock. Good for my piece of mind in regards to vapor lock in the RV12, but so awfully sad that someone died in a Van's RV12, especially since everyone knew there was some sort of issue with the engine prior to flight.
 
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Joe,

I have never had an engine stumble, but I have had Bitc*@n Betty yelling in my ear about hi fuel flow and low fuel pressure until I turned on my boost pump. That’s what you will likely get as an indication of vapor lock.

Rich
 
Joe,

I have never had an engine stumble, but I have had Bitc*@n Betty yelling in my ear about hi fuel flow and low fuel pressure until I turned on my boost pump. That’s what you will likely get as an indication of vapor lock.

Rich

Any hypothesis on why vapor lock would cause EFIS to sense high fuel flow?
 
Gas station near me has a sticker on pump telling date of Winter/Summer fuel changeover. Never saw that before…
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Any hypothesis on why vapor lock would cause EFIS to sense high fuel flow?
I've had this happen. For a while, any time I got above 7000 MSL I'd get Ms. Dynon screaming, "FUEL FLOW HIGH!!" in my ear. My hypothesis is/was that there were air bubbles forming in the fuel line (all I could think of that would cause it, and it only happened at higher altitudes) that were allowing some unusual flow patterns through the fuel flow sensor. The sensor is a little turbine wheel with a single optical sensor, which will count one tick whether the wheel is moving forward or backward. It's not smart enough to sense which direction the fuel is flowing, just the rate. If it starts getting spun back and forth both directions due to vibration, expanding and collapsing air bubbles, or both, cavitation, whatever then it's going to start double counting.

At lower altitudes it was not a problem. I don't recall whether I tried AVGAS or not, to be honest -- this was a couple of years back.
 
Harking back to my courses on fluid flow the vapor causes a lot of stuff to be going on: reduces average density, bubbles move faster than the fluid, and pressure drop increases in the two phase areas. I always attributed the final effect to be the red cube turbine turns faster giving the high fuel flow indication.
 
I've had this happen. For a while, any time I got above 7000 MSL I'd get Ms. Dynon screaming, "FUEL FLOW HIGH!!" in my ear. My hypothesis is/was that there were air bubbles forming in the fuel line (all I could think of that would cause it, and it only happened at higher altitudes) that were allowing some unusual flow patterns through the fuel flow sensor. The sensor is a little turbine wheel with a single optical sensor, which will count one tick whether the wheel is moving forward or backward. It's not smart enough to sense which direction the fuel is flowing, just the rate. If it starts getting spun back and forth both directions due to vibration, expanding and collapsing air bubbles, or both, cavitation, whatever then it's going to start double counting.

At lower altitudes it was not a problem. I don't recall whether I tried AVGAS or not, to be honest -- this was a couple of years back.



I'm trying to learn everything I can about the 912ULS and vapor lock issues, so I'm clearly not an expert, but the first thing that I would have checked is the possibility of a defective/worn out/not properly seated carb diaphragm(s). The diaphragm is responsible for leaning the engine as you go up in altitude. If there was a problem with carb diaphragm(s) you would have been running extremely rich by the time you got to 7000 ft. Now whether that would cause High Fuel Flow warnings from the EFIS, I don't know. Maybe someone else can chime in on that. If the issue happened multiple times at or above 7000 ft. where it's normally below 80 degrees and the fact that vapor lock is hard to reliably replicate, vapor lock wouldn't be my first guess.

I don't remember the exact altitude, but at a certain point between 7000-9000 ft the diaphragms reach the limit of their leaning capabilities..


EDIT: The posted info below about the Van's Service Letter seems to better explain the issue involving high fuel flow warnings at altitude..
 
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I'm trying to learn everything I can about the 912ULS and vapor lock issues, so I'm clearly not an expert, but the first thing that I would have checked is the possibility of a defective/worn out/not properly seated carb diaphragm(s). The diaphragm is responsible for leaning the engine as you go up in altitude. If there was a problem with carb diaphragm(s) you would have been running extremely rich by the time you got to 7000 ft. Now whether that would cause High Fuel Flow warnings from the EFIS, I don't know. Maybe someone else can chime in on that. If the issue happened multiple times at or above 7000 ft. where it's normally below 80 degrees and the fact that vapor lock is hard to reliably replicate, vapor lock wouldn't be my first guess.

I don't remember the exact altitude, but at a certain point between 7000-9000 ft the diaphragms reach the limit of their leaning capabilities..
They were fine, and I knew they were fine, having checked them fairly recently. The Dynon was telling me my fuel flow had suddenly jumped from the normal 5-6 GPH to over 10, and after confirming that I wasn't pumping fuel overboard from a broken line I concluded that it was in erroneous indication.
 
There seems to be a typo on page 2 of "Service Letter 19-09-23". It says,
". . . we recommend that aircraft . . . turn off the high PRESSURE warning . . .
I believe that Van's meant to write, "turn off the high fuel FLOW warning".
 
I will begin using 12VDC Standard Brushless Cooling Fan 120mm x 25mm Dual Ball Bearing 3.0 Watt 45 CFM (Amazon - $10) when airplane is “parked” such as pancake fly-ins, $100 hamburger run, refueling, and potty stops. Fan draws 0.25A so it can run for long time with minimal battery drain. Fan plugs into battery charging pigtail, so no installation to speak of. When I return the plane to the hanger, I will continue practice of leaving oil door open.
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I just installed the FAC-40135 Facet Cube 12v Fuel Pump per Van’s Notice N 18-07-12 and now see 5 psig with electric pump where original pump only made 3 psig when operating by itself. Haven’t flown yet, so I don’t know the combined fuel pressure when mechanical pump is adding to the system. New pump is louder than original pump…
 
I just installed the FAC-40135 Facet Cube 12v Fuel Pump per Van’s Notice N 18-07-12 and now see 5 psig with electric pump where original pump only made 3 psig when operating by itself. Haven’t flown yet, so I don’t know the combined fuel pressure when mechanical pump is adding to the system. New pump is louder than original pump…

That sounds good.. Mine is on order from Van's and will hopefully get here in a few days..
 
I hate climbing back into the baggage compartment for annual when I inspect the pump. I’ve found that tossing a couple of bean bag chairs into the cockpit after I pull out the seats reduces the aches and pains from the flap handle and everything else that would be poking me.
 
I flew 1.2 this morning to test the new 40135 Facet electric fuel pump. Looks like 5 psig fuel pressure in cruise flight which is about a 1 psig gain. There might be an improvement in fuel pressure during full-throttle climb. OAT was 48F – I used engine preheat before flight because airplane was cold-soaked. Not a whole lot else to report. Next post will be when weather gets 80+F.
 
80F! Jim, that’s balmy in PHX! All kidding aside I haven’t experienced vapor lock symptoms below the upper 90s.

Rich
 
Hi all,

Interesting thread. I am getting back into aviation after 20 years and I'm considering an RV12. Admittedly my brain is having to "warm up" to the idea of Rotax engines since I am coming from Lycs, Continentals, round engines and turbines. In general I like what I see and I really appreciate forums like this to help myself and others learn from experiences that we'd rather not have ourselves! I've flown several gliders and I don't have a glider rating. It's exciting at best.

Seagull made and interesting point in post #69 regarding the fact that the only lines in the system that don't experience return fuel circulation are the feed lines from the tree to the carbs.

Prepare to experience my ignorance, but I'm an engineer so most of my ideas don't work :D ! Would it be possible to install a "T" at each carburetor inlet and allow fuel to bypass and return from that point thus circulating fuel through the feed lines as well?

More of a thought experiment than anything else. I don't have any real experience messing with Rotax engines.

Kind regards to all!
 
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Russ,

My understanding of the fuel system is that you are not just reducing fuel line temperature with recirc flow, we rely on boost pump discharge pressure too in order to prevent vapor lock. Adding another bypass flow path might drop the boost pump discharge pressure and promote vapor lock.

Rich
 
Rich,

Good point. I looked at the pressure vs flow graph for the Facet Cube pump, and at 5 PSI, it can maintain about 8 GPH so one would have to control the return flow rate through any additional lines to keep things in the proper range.
 
Today was first day I had to try my cooling fan to help vent under-cowl heat when plane is parked. OAT was mid-70F and I parked the plane for a twenty-minute potty stop. I placed the cooling fan over the open oil door and plugged into the receptacle I use for battery charging when in the hanger.

The fan works incredibly well. Lots of heat pulled out by the fan. When I came back twenty minutes later the fan was blowing relatively cool air. I still run the electric fuel pump for several minutes to recirculate fuel from the tank prior to engine start and flight continuation.

See post…. https://vansairforce.net/community/showpost.php?p=1522183&postcount=135
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Today was first day I had to try my cooling fan to help vent under-cowl heat when plane is parked. OAT was mid-70F and I parked the plane for a twenty-minute potty stop. I placed the cooling fan over the open oil door and plugged into the receptacle I use for battery charging when in the hanger.

The fan works incredibly well. Lots of heat pulled out by the fan. When I came back twenty minutes later the fan was blowing relatively cool air. I still run the electric fuel pump for several minutes to recirculate fuel from the tank prior to engine start and flight continuation.

See post…. https://vansairforce.net/community/showpost.php?p=1522183&postcount=135
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How much battery did you suck down? I'm guessing not much but it would be interesting to see what your battery was at when you shut down and what it was after the cooling and started back up again?
 
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