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Top Heavy

"Hot-Hot"starts

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I am almost embarrassed to ask this question. I have read everything that has been written regarding a "Hot " start for the Bravo engine. The problem I have encountered twice in the last month is an embarrassing engine stall after landing on the ramp with the throttle closed and mixture at full rich (landing configuration). I have been unable to restart the Bravo engine despite nearly every hot start machination I have tried. Any advice is welcome.

   Top Heavy

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After taxiing off the runway?

Some engines stall just after landing... a resetting of idle rpm is usually the fix...

PP thoughts only, not a mechanic...

Best regards,

-a-

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  Upon landing, your engine and cowling area are actually pretty cool, temps are at there lowest point for 30 seconds or so.  Maybe a normal start procedure is what the doctor ordered instead of a hot start procedure.  As soon as your landing roll is under control you may try to lean the mixture for ground operations which may help keep the engine running, but I would also seek the input of a mechanic as to why it's stalling.

 

Ron

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I had that happen with an Ovation where it would not run well at idle. New spark plugs made the difference. The Bravo really likes fine wire plugs.

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18 hours ago, Top Heavy said:

I am almost embarrassed to ask this question. I have read everything that has been written regarding a "Hot " start for the Bravo engine. The problem I have encountered twice in the last month is an embarrassing engine stall after landing on the ramp with the throttle closed and mixture at full rich (landing configuration). I have been unable to restart the Bravo engine despite nearly every hot start machination I have tried. Any advice is welcome.

   Top Heavy

I would never have that engine with full mixture on the ground. You're fouling up your plugs. Lean it pretty aggressively for ground ops. Also, no reason to push full forward for landing.

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My 231 is set up very rich in order to make the necessary fuel flow for takeoff and climb.  As a result, the engine "burbles" during short final if I don't lean it out.  One remedy is to lean the fuel flow for landing, which is my normal configuration.  If I need to go around, which is rare, I put in the mixture and the throttle.  It works fine.  So that is what I would do, you can lean the engine heavily on short final, the descent drives the prop.  The thing with this method that can cause an engine stoppage is that I have to put in some mixture once I am on the ground, because the prop is no longer getting any help during taxi, and it will quit if you don't enrich.

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You have two questions there. The idle mixture has been addressed, let's address hot starts.

I just finished re-reading John Deakin's series of articles on operating turbocharged engines. For  a hot engine that won't start (he's specifically talking about TCM engines, but this also works for the TIO-540 in the TLS/Bravo),  he recommends pulling the mixture to idle-cutoff and running the fuel pump for a full minute, then use normal start procedures. The purpose is to cool the fuel pump and clear any vaporized fuel in the lines. I happened on a similar procedure through troubleshooting a hot engine that would fire for a few blades and then quit, during a fuel stop in Pueblo (100+ degree day and high DA). Only run the pump with the mixture in idle-cutoff, otherwise you'll be dumping a lot of raw fuel into your hot engine, which could turn out very poorly. Here's a link to the article where he talks through this: https://www.avweb.com/news/pelican/182105-1.html The article covers more than just hot starts, and talks about another favorite topic here on Mooneyspace that I am NOT trying to restart here...

Did you do anything other than letting the engine cool when you had the shut down issue? How long after you turned the boost pump off after landing did the engine shut down? What were the ambient temperatures and DA? It may more likely be a vapor lock issue than plugs if all you did was let it cool, however I agree that checking the idle mixture and for fouled plugs is a good place to start. Something else you can check is the fuel pressure as you taxi to the ramp, and also as you attempt a hot start. If you notice the fuel pressure wavering during taxi, or no fuel pressure while you're cranking the engine on start, its likely that things are hot enough to cause vapor problems in the fuel system, or even that your engine driven fuel pump is getting worn out.

Cheers,

Rick

Edited by Junkman
Added link to Pelican's Perch article

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I had difficulty starting my Bravo especially when hot, it always started fine, Inhad Weber check it out and the timing was off 6*, reset the timing now it behaves and starts nicely when hot, I do have fine wires

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On 9/16/2017 at 10:10 AM, Junkman said:

You have two questions there. The idle mixture has been addressed, let's address hot starts.

I just finished re-reading John Deakin's series of articles on operating turbocharged engines. For  a hot engine that won't start (he's specifically talking about TCM engines, but this also works for the TIO-540 in the TLS/Bravo),  he recommends pulling the mixture to idle-cutoff and running the fuel pump for a full minute, then use normal start procedures. The purpose is to cool the fuel pump and clear any vaporized fuel in the lines. I happened on a similar procedure through troubleshooting a hot engine that would fire for a few blades and then quit, during a fuel stop in Pueblo (100+ degree day and high DA). Only run the pump with the mixture in idle-cutoff, otherwise you'll be dumping a lot of raw fuel into your hot engine, which could turn out very poorly. Here's a link to the article where he talks through this: https://www.avweb.com/news/pelican/182105-1.html The article covers more than just hot starts, and talks about another favorite topic here on Mooneyspace that I am NOT trying to restart here...

Did you do anything other than letting the engine cool when you had the shut down issue? How long after you turned the boost pump off after landing did the engine shut down? What were the ambient temperatures and DA? It may more likely be a vapor lock issue than plugs if all you did was let it cool, however I agree that checking the idle mixture and for fouled plugs is a good place to start. Something else you can check is the fuel pressure as you taxi to the ramp, and also as you attempt a hot start. If you notice the fuel pressure wavering during taxi, or no fuel pressure while you're cranking the engine on start, its likely that things are hot enough to cause vapor problems in the fuel system, or even that your engine driven fuel pump is getting worn out.

Cheers,

Rick

That's exactly how I do it on both planes I have which have different versions of the IO-540. 

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I used to have that problem on hot days intermittently, or quick turnarounds, and 95% of the time, one of the many techniques worked as all mentioned above. I was wanting to go places where there is no external battery, so I wondered what would happen if I had trouble starting in the middle of nowhere airport. So I purchased a slick start ->

http://www.aircraftspruce.com/catalog/eppages/slickstart.php?clickkey=6866

and almost no matter what i do, hot start, cold start, flood then lean start to mixture in, full rich warm starts, half rich hot starts, and they all seem to just work similar to starting a car. It seems like cheating it's so easy now, but now i never worry whether my plane will start on the first or at most second try.

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Just beware of that “run the pump for one minute” technique.  It no doubt works fine on the big bore TCM turbos in the Bonanzas those GAMI guys fly, but in my TCM TSIO360LB, running the boost that long will cause a backfire.  I do it- run the boost with idle mixture at cutoff - but only until the fuel pressure stabilizes.  All that’s really necessary is to make sure the lines are full, and stop there.  

During start the engine may fire and then try to quit.  That’s the point where you need to use the boost pump a little, just leave the safety cage on and touch the top of the switch.  This makes the switch an “instant off” switch.  When you hear the engine try to quit, just push the top of the boost switch a little and the engine will get the fuel it needs until the mechanical pump starts to work.

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