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ibjet

Engine quit in flight

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Please see the 2 questions in bold print.

I made a sight seeing flight from Kingman airport, AZ over Supai AZ to see the Havasu falls/Mooney falls. There is no airport there so it was an out and back, about an hour and 40 minutes. I had about 15 to 18 gallons of fuel onboard. We made a straight in landing approach for Rwy 21 at Kingman. At about 4 miles out I decided I was too high and cut back to idle. Shortly after that the engine started missing. I played with the throttle setting many times and higher throttle made the engine vibrate like some cylinders were missing. I ended up lining up for an off field landing 2 different times, with the engine totally dying once. I was lined up on a field and decided to crank it and it re-started. We climbed a bit and then it lost power again so I lined up for a better field landing, but had to dodge some cows! But, played with the throttle again and got some more power. I was able to climb very cautiously and so I lined up with the runway and made a pretty normal landing. I taxed to my hangar and did a normal mag check - went fine.

In flight I had looked at the right fuel indicator and it showed about 8 gallons. I can't remember if I even looked at the left side but it almost always has more.

So, today I went back to my hangar to check it out (I was convinced it had been carburetor icing). To my shock the left tank showed totally empty in the indicator tube. I opened the gas filler and that area showed dry. Even shook the wing and it didn't sound like the left side made any sloshing noise, though the right side did.

I have this condition where the left tank always seems to draw gas out of the right tank while sitting in the hangar. I measured tilt today with a digital level and the right wing was about 0.1/0.2 degrees higher. But, the crazy thing - the gas did not transfer this time, stayed in the right wing leaving the left wing empty! I even propped the right wing up about an inch and left for about an hour. I came back with 10 more gallons of gas and the left tank was still showing empty.

I know there are some posts about needing to tilt the airplane in flight to make sure it uses fuel from the fuller tank. But, I was not sure if I had read (or that I believed) that one tank going empty would cause engine starvation.

So, can anyone verify that on a normal CTSW one empty tank will cause engine starvation? Mine is a 2006. I am in shock that I can have 8 gallons of gas and my engine can quit! Just seems like FD would not have let that be. I do not remember any cautions about this in the owners manuals. And, it is very hard to see the levels in the tubes in flight, especially for the left tank if you are in the left seat. 

One more question while I'm at it: I was also baffled about the Carburetor Heat system. In the past when I have pulled it on to test it, I get no RPM drop. I actually got out of the habit of testing it because of that. Today I removed the upper engine cowling and pulled the carburetor heat fully on. I could hear the door inside the intake hitting the full travel stop inside the intake (and I could see that the arm had moved a lot. So: Am I supposed to have an RPM drop when I activate it fully? I did not start it up and re-verify this time. And I don't think I have done it during the 3000 RPM mag check. Thanks in advance for any input.

We did get some nice pictures and Hazel even took 3 video's (which I could not download to my PC, dang. We did upload one of them to Facebook. Posting a few pics . . .

Thanks,

ET 

Havasu_Falls_Arizona2.jpg

inflight pic bound for Supai.jpg

Mooney Falls, Supai, AZ2.jpg

Over Supai.jpg

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The CT will run perfectly fine with one tank empty, unless there is some other issue with the system, (restricted flow in the line of the tank with fuel). The key is you need to keep the fuel at the inboard end of the tank that has fuel in it. If it goes outboard the engine will not get fuel. If you added a little slip with your power reduction that could have un-ported the tank, the CT will yaw to the right with a power reduction.

The carb heat design on the CTSW will not cause a drop in RPM like most systems. Think of it as an alternate air source rather than carb heat. With the Rotax carb ice will normally occur when the temps are in the mid 50's with visible moisture in the air, at least that is the common thinking.

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What Tom said. Since the left tank drains faster start flying your longer flights with the ball 1/2 out to the left. This will equal your overall fuel flow. As Tom said if you get low on fuel and one tank is empty and your are out of coordination to the right tank some then the fuel will move away from the inner wing root and out towards the outer part of of tank away from the fuel pick up.

If you want to transfer fuel from the right wing to your left fly 1 ball out to the left.

All this is a function of a flat fuel tank. Some certified aircraft have the same issue.

You will not have an rpm drop on a CTSW with carb heat and especially on the ground.

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With the left tank still empty, open the gascolator drain and see if you get normal fuel flow.  If not, you have something wrong in the fuel path from the right tank to the engine  -- pinched hose, debris in the hose, clogged wing root strainer -- something.  

If you're already put fuel in the left tank, open the gascolator drain and drain the fuel back into your gas cans.  If you only see the fuel level going down in  the left tank, keep draining until all the fuel is gone from the left.  If the fuel then stops and there is still fuel in the right, again you have a right side fuel path issue.

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31 minutes ago, FlyingMonkey said:

With the left tank still empty, open the gascolator drain and see if you get normal fuel flow.  If not, you have something wrong in the fuel path from the right tank to the engine  -- pinched hose, debris in the hose, clogged wing root strainer -- something.  

If you're already put fuel in the left tank, open the gascolator drain and drain the fuel back into your gas cans.  If you only see the fuel level going down in  the left tank, keep draining until all the fuel is gone from the left.  If the fuel then stops and there is still fuel in the right, again you have a right side fuel path issue.

Excellent troubleshooting technique.

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Engine rough when you gave  throttle sounds like debris in the float bowl that gets into the jet.

Running out of fuel doesn't seem to fit with roughness or restart.

Are both the gas cap vents clear?

Did you do a flow test at annual time?

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Thanks for all the great input gentlemen! 

Yes, I did the flow test with my annual. It drove me crazy 'cause I could not pass when going thru the gascolator drain. When I took the gascolator bowl off, the flow from each tank was fine, more than 10 gallons per hour as I remember. 

I did check the fuel cap vents at annual, was not sure about how clear they were so I soaked them each in acetone and blew them out with compressed air and they seemed the same (definitely had air flow). I also adjusted them so they faced forward more correctly then they had been (I had also installed new O-rings so needed to correct the pointing of the vent tubes). I also removed the carburetor bowls at the end of my annual and drained them out by suction tube (syphoned). I did not get any debris, but the gas looked like whiskey, I was very glad I took the trouble to drain them!

As I said, after thinking thru everything that had happened, I decided it was probably carb ice and it was worse on one side of the engine than the other (accounting for the vibration when I applied increased throttle). And, since I got the confirmation that one empty tank will not cause gas starvation, I am back leaning toward that as my prime suspect. It did run fine for the long taxi to my hangar and did fine with my mag check which would indicate possibly that the icing issue was cleared up because of the ground level temps (probably about 70 by about 5 pm). So, in flight when I cut throttle to idle, I was probably still at 6,000, had been in much cooler air and there was a cloud base at around 10,000 and fairly moist air. Of course when you cut to idle that is when you get maximum pressure differential in your carburetor, max temp drop right at the slide. 

I've got 10 gallons in the left tank now and about 8 in the right. I'll go see if it has done the normal overnight transferring from the right tank into the left tank. I would expect to see the right tank quite a bit lower now. Just not sure how fast/slow that transfer is. But, the plane is sitting with the right wing higher by about 0.1/0.2 degrees. I'll also do a calibration of my digital level at home first and see if I can nail that down better. 

Still baffled that the gas in the right wing did not transfer to the left wing Saturday (even tilted it more Sunday for about an hour. It seems like when that gas line from the tank to the gascolator is empty, you get an air bound situation. And, that should clear up once you have a good quantity of gas in that tank (hopefully)!!! If not it would fix itself once you do some flying. 

I plan to do a run up today, maybe a high speed taxi, then probably fly it locally and climb fairly high and put some time on it. Kingman has a really long runway so I'll set it right back down if it misses at all. 

I will do at least one more post here. I really wish I had done that flow test before putting in the 10 gallons. Might drain the left tank again but it would also drain the right at the same time so I'd fill 4 gas cans in the process. 

But, now I know my carb heat is working (have verified full travel of the flap inside the air cleaner box). So, lesson learned, I certainly will pull that carb heat control all the way out if I have this problem again. 

Again gentlemen, It is so awesome to have this great knowledge base, really appreciate the effort, give yourselves a big pat on the back! 

Thank you!

ET

 

 

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29 minutes ago, Roger Lee said:

This isn't a new subject. We have been discussing this since 2007.

Yes, that’s right.

I always liked (and follow) the tips and advice Ed Cesnalis gave to us. It is very simple . . . yet very effective.

“If you can see the fuel . . . so can your engine.”

“The fuel follows the ball.” (trim ball).

**That is assuming there is no obstruction with the feed lines.  Thank you Andy, for that reminder!

 

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4 hours ago, ibjet said:

 

As I said, after thinking thru everything that had happened, I decided it was probably carb ice and it was worse on one side of the engine than the other (accounting for the vibration when I applied increased throttle). And, since I got the confirmation that one empty tank will not cause gas starvation, I am back leaning toward that as my prime suspect. 

I think you had fuel starvation, not carb ice.

* Rotax engines are very resistant to carb ice.  I have flow my CT for five years, and have not seen carb ice, not even once.  This include flights all across the USA in all kinds of conditions with temps from 0°F to 100°F+ and all kinds of humidity conditions.  Carb ice is possible, but very rare.  The most common ice conditions for us are around 60°F OAT and 90% humidity or higher.  What were the conditions during the flight in question?

* You have confirmed that there was an empty fuel tank, which puts you at risk for starvation.

* Your statement  "I got the confirmation that one empty tank will not cause gas starvation" is not really correct.  An empty tank will not cause starvation in itself, but if one tank is empty and the other partially full (the condition on the flight in question) AND you fly uncoordinated (very common in a CT), it ABSOLUTELY can result in starvation.  Ask Buckaroo, he had an off-airport landing in a field very soon after getting his CTSW, due precisely to this.  

As Roger said, this has been beat to death numerous times in this forum.  I have said numerous times that the safest course of action is to never run a tank empty in the CT.  Balance the fuel tanks in flight with rudder trim to keep them roughly even, or at least with both showing fuel in the sight tubes, and you will *never* have this kind of starvation issue.  If you do that, no matter what flight attitude you are in there will always be fuel at one or the other fuel pickup.   The CT fuel system is "quirky" but a piece of cake to manage.

Never check just one sight tube, always check both.  Balance them out if you don't see fuel in one.  If you come away from this experience saying "well it's just carb ice..." and don't takes steps to better manage your CT's fuel, I'd bet that we'll be reading a thread on here about another similar incident down the road.  Look back in the forum history, you'll find numerous similar incidents, all fuel related.  In fact I'm sure they have happened, but I'm struggling to recall any engine out resulting in an off-airport landing or crash in a CT that didn't involve fuel mismanagement in a CT.

Thus endeth the sermon, ignore it at thy peril. 

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12 minutes ago, FlyingMonkey said:

I think you had fuel starvation, not carb ice.

* Rotax engines are very resistant to carb ice.  I have flow my CT for five years, and have not seen carb ice, not even once.  This include flights all across the USA in all kinds of conditions with temps from 0°F to 100°F+ and all kinds of humidity conditions.  Carb ice is possible, but very rare.  The most common ice conditions for us are around 60°F OAT and 90% humidity or higher.  What were the conditions during the flight in question?

* You have confirmed that there was an empty fuel tank, which puts you at risk for starvation.

* Your statement  "I got the confirmation that one empty tank will not cause gas starvation" is not really correct.  An empty tank will not cause starvation in itself, but if one tank is empty and the other partially full (the condition on the flight in question) AND you fly uncoordinated (very common in a CT), it ABSOLUTELY can result in starvation.  Ask Buckaroo, he had an off-airport landing in a field very soon after getting his CTSW, due precisely to this.  

As Roger said, this has been beat to death numerous times in this forum.  I have said numerous times that the safest course of action is to never run a tank empty in the CT.  Balance the fuel tanks in flight with rudder trim to keep them roughly even, or at least with both showing fuel in the sight tubes, and you will *never* have this kind of starvation issue.  If you do that, no matter what flight attitude you are in there will always be fuel at one or the other fuel pickup.   The CT fuel system is "quirky" but a piece of cake to manage.

Never check just one sight tube, always check both.  Balance them out if you don't see fuel in one.  If you come away from this experience saying "well it's just carb ice..." and don't takes steps to better manage your CT's fuel, I'd bet that we'll be reading a thread on here about another similar incident down the road.  Look back in the forum history, you'll find numerous similar incidents, all fuel related.  In fact I'm sure they have happened, but I'm struggling to recall any engine out resulting in an off-airport landing or crash in a CT that didn't involve fuel mismanagement in a CT.

Thus endeth the sermon, ignore it at thy peril. 

Excellent narrative.

Concur with the assertion.

 

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Yup, my left tube went empty. My right showed approximately 8 gallons. I immediately became concerned and cranked the plane in a left turn towards 8U8. Straitened out and engine quit like right now. Looked at the right tube and wallah empty. Landed her in fresh Alphalpha field and behold 8 gallons appears back in right tube. 

The tanks are flat and long. You can sling fuel out very fast by skidding. My engine quit almost immediately upon recognizing momentary loss of fuel in the line. 

I would bet money that you may of been bouncing fuel back and forth by rudder action against the bottom of the tube. 

Cool pictures! 

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Wow, I am amazed at the "brain trust" here. Thanks gentlemen! I was on a 4 mile final and pretty well lined up with the runway, but I'm sure I did some rudder input to correct my alignment with the runway. 

Thank you very very much for these last 3 inputs, you've changed my attitude, I was convinced I didn't need to worry about which tank my fuel was residing in, ha ha. Now I realize the importance of balancing it. 

I did over an hour of flying yesterday. The second time I climbed to 10,000 then throttled to idle and descended all the way back until I was pattern altitude at Kingman. Never any problem at all with the engine and it didn't stumble when I added power (both my previous airplanes had that issue). There might not have been as much moisture in the air as last Friday, but if I can cut to idle abruptly at 10,000 with no issues, I'm happy. I love the Rotax 912!

Many thanks!!!

ET

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22 hours ago, FlyingMonkey said:

Balance them out if you don't see fuel in one. 

Andy gave lots of good insight but I might differ on what to do if one tank is empty.

To be at risk you need to have one tank empty and the other low enough where you can slosh the remaining fuel outboard away from the pickup at the wing root.  You can't do this with a full tank.

I prefer to have all my fuel in one tank if I get very low. If I can see fuel I'm safe and if its all in one tank keeping it visible is straitforward and lasts longer.  Even after there is no fuel visible there are still moments left.  If all fuel is on one side you can postpone that event even longer.  If you try to go all the way to empty balanced to the last drop you will loose sight sooner in the sequence and become clueless.

 

=================== edit ===================

Another way of saying this, if you 'don't see fuel in one' (and are low in the other) then the act of balancing would often make the remaining visible fuel invisible too.  I can only effectively manage fuel I can see.

 

 

 

 

 

 

 

 

 

 

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I wonder if the new Flight Design Super Sport will have a fuel selector and header tank? Maybe just a fuel selector? 

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2 hours ago, Ed Cesnalis said:

Andy gave lots of good insight but I might differ on what to do if one tank is empty.

To be at risk you need to have one tank empty and the other low enough where you can slosh the remaining fuel outboard away from the pickup at the wing root.  You can't do this with a full tank.

I prefer to have all my fuel in one tank if I get very low. If I can see fuel I'm safe and if its all in one tank keeping it visible is straitforward and lasts longer.  Even after there is no fuel visible there are still moments left.  If all fuel is on one side you can postpone that event even longer.  If you try to go all the way to empty balanced to the last drop you will loose sight sooner in the sequence and become clueless.

You and I have had this minor quibble before, but I think we agree on 95% of the fuel management picture.  If it makes you fee better we can amend my procedure to "visually confirm fuel level in the 'full' tank before making any balancing changes."

Ed, with your level of experience with this airplane, I think you know what's going on with your fuel far better than the "average" CT pilot.  My method is designed to keep you out of trouble, and it is definitely most effective when you monitor your fuel periodically and balance as needed.  Once you have an empty tank you have a different set of issues regarding fuel management.  I would say don't manage your fuel in such a way that having an empty tank comes up.  :)

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3 hours ago, Ed Cesnalis said:

I prefer to have all my fuel in one tank if I get very low. If I can see fuel I'm safe and if its all in one tank keeping it visible is straitforward and lasts longer.  Even after there is no fuel visible there are still moments left.  If all fuel is on one side you can postpone that event even longer.  If you try to go all the way to empty balanced to the last drop you will loose sight sooner in the sequence and become clueless.

In the CTSW (with no fuel tank selector valve), if one tank is empty, and the other tank is at least half full, what prevents you from transferring fuel to the empty tank?

Put another way . . . what keeps fuel from transferring from the full tank to the empty tank, while keeping the full tank supply port covered with fuel, to supply fuel to the engine?

In that scenario, I see no way to avoid such a transfer . . . like it or not.

That withstanding, I understand transferring rate is dependent on head pressure from the supplying tank.

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6 hours ago, WmInce said:

In the CTSW (with no fuel tank selector valve), if one tank is empty, and the other tank is at least half full, what prevents you from transferring fuel to the empty tank?

Actually you can't prevent it. 8 1/2 gallons is enough where you can't slosh it outboard and it will self balance unless you fight it.

When 8 1/2 changes to 2 1/2 I prefer to keep it on one side to better keep it visible longer

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I've had carb ice on 2 occasions; on cold days with lots of haze, and reduced throttle. The carb ice pull stops it immediately.

When the plane was fairly new to me, I ran one tank out and unported the other one. The engine ran fine as soon as I leveled the wings.

I've played with the vent tubes, but I've never got them to draw the same. My left tank always uses more if I don't fly left wing low. 

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34 minutes ago, Stacy said:

I've had carb ice on 2 occasions; on cold days with lots of haze, and reduced throttle. The carb ice pull stops it immediately.

When the plane was fairly new to me, I ran one tank out and unported the other one. The engine ran fine as soon as I leveled the wings.

I've played with the vent tubes, but I've never got them to draw the same. My left tank always uses more if I don't fly left wing low. 

All airplanes are hand made, it's common for each airplane to have a fuel tank with higher flow than the other.  There is just no way that all that hand-laid composite is not going to have variances that add up to a higher head pressure for one tank than the other.  No big deal once you figure out how tanks flow for your particular airplane.  Mine likes to flow from the left tank a bit more.  I usually put more fuel in the left side as a result.  Though I have also found that my airplane flows much more evenly now than when I first got it...so some of the difference might have been my bad initial technique and the yaw-happy nature of the CT.

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On 4/10/2019 at 5:59 AM, Ed Cesnalis said:

Actually you can't prevent it. 8 1/2 gallons is enough where you can't slosh it outboard and it will self balance unless you fight it.

When 8 1/2 changes to 2 1/2 I prefer to keep it on one side to better keep it visible longer

Concur, Ed.

That was the point I was subtly trying to make.😃

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1 hour ago, WmInce said:

Concur, Ed.

That was the point I was subtly trying to make.😃

Going forward with Dynons I will have the fuel management features.  Having fuel levels for both tanks I might want to keep them balanced so my gauges would be correct on quantity and location.

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1 hour ago, Ed Cesnalis said:

Going forward with Dynons I will have the fuel management features.  Having fuel levels for both tanks I might want to keep them balanced so my gauges would be correct on quantity and location.

Are you saying your Dynons have fuel gauges for each tank? (quantity and location)

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The dynon's do not have a fuel gauge.  The skyview does have the ability to program takeoff fuel and then compute the fuel burn but that is only a computation.  The system has nothing in the tank to measure what is actually there.  You can have a leak or missing fuel cap and you will only know it by watching the fuel sight tubes.

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I am pretty sure the skyview system can do fuel flow which is not just a computation but actual measurement - of course that is not going to help you if you have a leak somewhere.

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