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  #11  
Old 06-02-2013, 08:56 AM
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Flyguytki Flyguytki is offline
 
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Quote:
Originally Posted by Wayne Gillispie View Post
This is a forum where we all come to discuss and learn and this looks like a perfect opportunity. Fixed pitch or CS? Exhaust valve sticking? Glad you made it back on the ground safely!
I agree, I know there is alot of knowledge here so hopefully I can get some help.



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  #12  
Old 06-02-2013, 11:57 AM
Wayne Gillispie Wayne Gillispie is offline
 
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Did you do a baseline compression test? I'd do one now and also boroscope cylinder #1.

Your max IAS shows 32.9 kts? I think your MP at idle on the ground should be around 10-12".

You may find you have more than one problem.
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Last edited by Wayne Gillispie : 06-02-2013 at 12:23 PM.
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  #13  
Old 06-02-2013, 07:14 PM
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Kevin Horton Kevin Horton is offline
 
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Good job getting safely back on the ground.

#1 cylinder looks like it goes lean at higher fuel flow, but runs OK at lower fuel flow. Look for some crud in the #1 fuel injection nozzle.
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  #14  
Old 06-02-2013, 08:04 PM
Wayne Gillispie Wayne Gillispie is offline
 
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He already troubleshot the nozzle..."We pulled the injectors in #1 even swapped then with another cylinder to see if when we did a run in the problem followed to the new cylinder but there was no change. And the max rpm is still 2080."
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  #15  
Old 06-02-2013, 10:49 PM
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Flyguytki Flyguytki is offline
 
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I am pleased to report I think we have solved the issue.

This morning, a group of 4 of us sat around and brainstormed everything that could possibly be the answer, we had the SavvyAnalysis up at the same time and we kept coming back to the same reasoning, Cylinder one had a fuel blockage at the time of the RPM decrease, this answered everything except for the low RPM on take off. Well after searching this site for about an hour, I came to the conclusion that Static RPM is not an exact science with this engine and prop combination. Some have reported static RPM's as low as 2100 all the way to 2400 Rpm. After some more troubleshooting we ran out of things to look for and decided the next thing to do was fly it again.

The take off was similar to yesterdays, 2050 RPM and airspeed was reading about 100kts on climb out. As I climbed through 1000 feet the RPM's steadily increased, increased increased, as I leveled off at 3000 feet, the RPMS were right at 2500, CHT's were reading 1250-1300 and EGTS were right at 410-420 while cruising laps around the airport at 160kts. After relaying all the info to the ground, i got the "Everything sounds normal" so i kept cruising, 48 minutes into the flight i started a slow decent straight into a base final and an OK landing. Needless to say, I am MUCH happier, Mike was even able to catch the "Grin" after I shut down.

I am going to go back out again tomorrow and see if things are the same, we suspect the low Static RPM is due to a brand new engine and some very thick mineral oil.

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  #16  
Old 06-02-2013, 11:11 PM
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RVG8tor RVG8tor is offline
 
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Default Great Job!

Quote:
Originally Posted by Flyguytki View Post
Brand new engine, the engine was only producing 2080 rpm and by the time I realized that was all it had, ( I brought throttle in VERY slowly) I was already airborne and wasn't positive I had enough runway remaining, so I began a shallow climb out and when I turned crosswind I lost apx 1000 rpm (I thought it quite on me), I had not touched anything prior to this point, as soon as it happened, I turned hard back to the airport and pulled the throttle back, considered landing opposite however I was a good 1200 feet in the air and I never would have made it to the runway I was way to fast and high with the runway directly below. At this point with the throttle pulled back to 1/4 throttle or so and the power felt as if it came back and it was running smoother so I continued downwind, turned a tight base, final, dumped some flaps, engine was at a lower rpm and again running smoother, cleared the fence at about 90 knots and floated forever, but it was a beautiful touchdown :-).

When I shutdown I got many questions of "what was this reading". I could not tell you until I downloaded the data, as I keep looking back on it, from the second I thought the engine quit I do not recall looking inside.

Our initial thought ( prior to downloading data, however we did have a gopro looking at one of the screens showing the ems that we could watch at the airport) was that I had stopped making power on the #1 cylinder, because the egt cht starting to climb faster than the other 3 cylinders and then when I had the loss of power it dropped completely off. Also the exhaust is very black, ie very rich, so our reasoning for the cylinder not firing is a plugged injector or blockage somewhere in the cylinder, that would make force more fuel to the other cylinders making then rich, #1 plug looks normal, #234 are VERY black. We pulled the injectors in #1 even swapped then with another cylinder to see if when we did a run in the problem followed to the new cylinder but there was no change. And the max rpm is still 2080.

Please no speculation on what I did wrong, I need to know what's going in with the engine and that's all, I have to give a huge thank you to RVG8TOR as he was flying chase and took care of the tower for me ( no emergency declared but they let us do whatever we needed to get back in the ground) so once again thanks mike.

If you think you might be able to give some insight please give me a call if you would. Two one four 7 3 3 two two six two

-david
I just flew and watched as you handled a very challenging situation like a pro. Congratulations on the first flight and well done.

Glad today's flight was much more normal, nice temps on the engine, I think you plenum will work out nicely.

Seems like only yesterday I was picking up your finish kit while you where still in Afghanistan. Let me know when you want to start some formation work!
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  #17  
Old 06-02-2013, 11:15 PM
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Flyguytki Flyguytki is offline
 
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Haha, ya it sure does doesnt it. I cant thank you enough for all you did for me, it was a HUGE help. We will start formations soon enough lol.

Heres a link to the data of todays flight. It looks much better, the GPS track is pretty funny too.

https://www.savvyanalysis.com/my-fli...f-ec73390ce7ea
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  #18  
Old 06-03-2013, 12:57 AM
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Quote:
Originally Posted by RVG8tor View Post
I just flew and watched as you handled a very challenging situation like a pro. Congratulations on the first flight and well done.

Glad today's flight was much more normal, nice temps on the engine, I think you plenum will work out nicely.

Seems like only yesterday I was picking up your finish kit while you where still in Afghanistan. Let me know when you want to start some formation work!
We were shooting emails across base in Afghanistan, got home about the same time, projects in about the same place. I'm not even CLOSE to done! I'm so jealous, congrats brother!!!
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  #19  
Old 06-03-2013, 01:06 PM
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Default RPM Spread

I agree that it looked like there was some kind of short term loss of fuel to #1 that cause the power disturbance. Congrats on successfully working through it!

Generally speaking, 400-450 RPM spread from Static to WOT on a fixed pitch prop is pretty "normal". It is the achilles heal of fixed pitch. I saw the same spread on several different props I ran on my Long-EZ. Ideally you should have top end (8000 ft / WOT) RPM of around 2650-2700, which would give you ~75% power at 8000 ft. That gives you the highest cruise speed and with electronic ignition and FI you can lean to get good fuel economy without having to throttle back. That would also give you around 2250 RPM Static. Your current 2080 RPM will definitely cut into your take off performance when you need it the most for Gross Wt, high density altitude operation. R
From my personally experiences, I wouldn't be comfortable with settling for that.

2500 RPM WOT is "nice" for WOT cruise, but you'll suffer top end speed from it also.

FP is a notable compromise on these "high speed range" aircraft.... so you have to decide how you are most often going to operate the plane and understand the associate limitations. If it were my plane, I'd seriously consider re-pitching or blade length to get some more RPM's...

Just my 2 cents...
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  #20  
Old 06-03-2013, 03:40 PM
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Flyguytki Flyguytki is offline
 
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Quote:
Originally Posted by rv9av8tr View Post
I agree that it looked like there was some kind of short term loss of fuel to #1 that cause the power disturbance. Congrats on successfully working through it!

Generally speaking, 400-450 RPM spread from Static to WOT on a fixed pitch prop is pretty "normal". It is the achilles heal of fixed pitch. I saw the same spread on several different props I ran on my Long-EZ. Ideally you should have top end (8000 ft / WOT) RPM of around 2650-2700, which would give you ~75% power at 8000 ft. That gives you the highest cruise speed and with electronic ignition and FI you can lean to get good fuel economy without having to throttle back. That would also give you around 2250 RPM Static. Your current 2080 RPM will definitely cut into your take off performance when you need it the most for Gross Wt, high density altitude operation. R
From my personally experiences, I wouldn't be comfortable with settling for that.

2500 RPM WOT is "nice" for WOT cruise, but you'll suffer top end speed from it also.

FP is a notable compromise on these "high speed range" aircraft.... so you have to decide how you are most often going to operate the plane and understand the associate limitations. If it were my plane, I'd seriously consider re-pitching or blade length to get some more RPM's...

Just my 2 cents...
I agree 100 percent, Whats interesting Is when I had purchased the propeller from Craig, we had discussed and he said this is the best match for the airplane. Currently I have a 74X70 however when I do searches for the same propller on VAF it seems everyone else has a smaller diameter and lower pitch than mine, Static RPM's for these are closer to 2200. However I did find a Gentelman from Australia with the same combo and he is making the EXACT same numbers as I am. I am going to give it a few more flights and see what happens. We talk that ground role is shorter, but jeez is it still quick. I am going to attemp a little more straight line stuff today and see what numbers I can get.
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