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  #161  
Old 06-16-2012, 06:27 PM
CraigC CraigC is offline
 
Join Date: May 2005
Location: Mesa, AZ
Posts: 209
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I only know what I have experienced. There have been articles of late by Mike Busch on fine wires. My massive plugs have had issues. But only in the last year.
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Mesa, AZ RV-8 SerNo 82582
Wings/Fuse N18VA Res
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  #162  
Old 06-17-2012, 05:13 PM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Location: St. Paul, MN.
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I think we've got this thing licked. Looks like the problem was a plugged injector.

Good, solid and powerful performance today.
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
Last article: "Gonna Finish This Sucker" (Kitplanes)
Waiting for the avionics kit (backordered: chip shortage)
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  #163  
Old 06-17-2012, 05:32 PM
rockwoodrv9 rockwoodrv9 is offline
 
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Location: Meridian ID, Aspen CO, Okemos MI
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I can imagine how nice it is to have figured out what the issue was with the engine. On a car, it is one thing, but on a plane, it is still one thing, but you are in the air!

Have fun putting on those hours to break in the engine.
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O-320 D2A
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  #164  
Old 06-17-2012, 07:07 PM
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Ironflight Ironflight is offline
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Location: Dayton, NV
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Great news Bob - it is always good when you can actually positively identify a cause, and then see the results of better performance once it is fixed.
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RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
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  #165  
Old 06-18-2012, 12:47 AM
CraigC CraigC is offline
 
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Location: Mesa, AZ
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Quote:
Originally Posted by LettersFromFlyoverCountry View Post
I think we've got this thing licked. Looks like the problem was a plugged injector.

Good, solid and powerful performance today.
Nice......
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Wings/Fuse N18VA Res
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  #166  
Old 06-18-2012, 07:18 PM
TThurston TThurston is offline
 
Join Date: Jan 2007
Location: Orem, UT
Posts: 213
Default Lessons learned?

Congratulations on getting things sorted out.

But I wonder...

As I've read about the issues you've discussed here over the past couple of months, it seems like there must be some lessons here that might be useful for those of us who are not yet finished, or even nearly finished.

I seem to remember a thread discussing concerns about ground testing an engine, and another about how to diagnose engine performance issues prior to first flight.

I wonder if perhaps in hindsight that the issues with your engine could have been caught prior to first fight (or 3rd or 4th flight). If so, how?

I hope this question doesn't sound like a criticism at all. It's not intended to be. I just know that I have very little experience, and hope to learn from the experience of others.
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  #167  
Old 06-18-2012, 09:56 PM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Quote:
Originally Posted by TThurston View Post
I wonder if perhaps in hindsight that the issues with your engine could have been caught prior to first fight (or 3rd or 4th flight). If so, how?
Search the forums. I started threads about chasing the suspicion of a static RPM two months ago. But here's the thing: They didn't start out as chasing engine performance problems. They started as a thread about the FAA's requirement for an hour of ground run time.

Read these for more extensive information on the search:

The paperwork challenge
Diagnosing engine performance
Installing mags

It started with what appeared to be a low static RPM, but there was some disagreement over what a proper static RPM should be given a prop combination, not to mention the inadvisability of excessive ground runs beyond 2000.

Eventually, we figured out that the problem was a mistimed mag, which might have been another forum thread actually, but it was extensively documented, including on that fine little RV building blog.

I would say the issue(s) of the engine has been going on -- and been documented -- in one fashion or another for about two months. Are they all related? We don't know now, we certainly had no way of knowing then. Was the blocked fuel injector the problem two months ago? I have no way of knowing that. Neither does anyone else

So the lesson is: You search for your problems one at a time and solve them to your satisfaction one at a time. Maybe another one crops up, maybe it doesn't. Maybe the problem of one hides within the problem of another.

The lesson is: You don't know. And you better be ready.

When all is said and done, you test and fix, test and fix. I've been doing that for months on this particular issue which may have several different causes disguised as one.

But, really, that starts the minute you put the engine on the engine mount. You're always looking for things that might go wrong...which is why I spent months on fuel flow testing, clamping of wires, securing of SCAT, chafing issues, oil leaks, pulling out
fuel and oil lines and having them made better.

And then there's this little baby. I found this while looking for problems that hadn't presented themselves yet. Imagine if I'd actually gone flying with this garbage.

I think people have to go into Phase I with eyes wide open on this point and understand that you're going to find things that go wrong, and then you diagnose and fix them as they occur, then test to see the effect of the fix. Make sure your flying is up to snuff. Make sure you didn't just take enough transition training to satisfy your insurance company. Make sure you're a **** of a test pilot.

Also, if you're lucky like me, you've met the best and brightest on Planet RV in the course of building, and when you think you might have a problem, they drop what they're doing and come to your hangar, giving up time with their families to help you out, or they call you from halfway across the country to lend a supportive ear and some advice, and never once -- not once -- make you feel stupid.

So the big lesson: Get yourself friends like that.
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
Last article: "Gonna Finish This Sucker" (Kitplanes)
Waiting for the avionics kit (backordered: chip shortage)

Last edited by LettersFromFlyoverCountry : 06-18-2012 at 10:31 PM.
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  #168  
Old 06-18-2012, 10:38 PM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default How wise and there is a big payoff

You have certainly done well and reported the events as they occurred with no sugar coating. I swear there is a common attitude that this Phase 1 testing is just a burden imposed on us builders with no rational justification. You and I know from our experience as first time builders that it is a risky time with MANY opportunities for failure. And, I know you know you are not out of the woods yet. Just to reinforce what you are already learning I'm sure is, these really are pretty good little airplanes. Thursday I climbed in our little RV-6A and flew by myself from Fayetteville, Arkansas at 6:40 am CDT to Ephrata, Washington, against the prevailing winds with fuel stops in Goodland, Kansas, Sheridan, Wyoming and Missoula, Montana and arrived at my destination at 7 pm CDT (5 pm PDT) that same evening. The airplane wasn't even breathing hard. I flew it at max power over a 170 mile course on Saturday averaging over 216 mph then headed home with an overnight stop in Sheridan only because I have no lights in race configuration. These are REAL AIRPLANES by any standard of reliability or performance with all of the building demands and integration and test requirements of any high quality, high performance airplane without the frail nature of some others. However, the "years in process" systems in the end do have to be integrated and tested for both function and performance and the faults detected and fixed.

Bob Axsom

Last edited by Bob Axsom : 06-18-2012 at 10:42 PM.
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  #169  
Old 06-19-2012, 09:02 PM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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(Cross posted from the blog)

Flight Test Follies: The drug test


It was pee-in-a-cup night for N614EF as the flight test period continues.

Although the plane performed much better once we removed crud from the #1 cylinder injector on Sunday, the exhaust gas temperature and the cylinder head temperature for the cylinder were higher than for other cylinders, indicating that perhaps the mixture was a little leaner in that cylinder than it should be.

So today I took the injection line off again and checked the injector again and, sure enough, there was a speck of dirt blocking things a bit; it wasn't as bad as what we pulled out of there on Sunday, but it was clearly enough to deprive the cylinder of all the fuel it needs to run efficiently and stay relatively cool.

You can see the small speck -- which looked like a flake of primer -- at the end of the safety wire I used to poke it out. You might have to click on the image to see it.



After that, I wanted to check all four lines to see if they were putting out a fairly equal amount of fuel. So I stuck some Dixie cups at each injector and flushed out the lines, dumped the fuel and then turned on the boost pump for 15 seconds.



Then I weighed each cup and found that each was within 1 gram or so. The last cup I weighed, the #4 cylinder, showed only 16 grams but I'm chocking this up to them being paper cups and some of the fuel leaking out of them in the time it took me to weigh the other three. Whatever, the #4 cylinder hasn't been much of a bother up to now.





So all that was left was to start the engine for a light look at things. It's too windy to do any flying. In about a 7 minute exercise, all four cylinder temperatures were within 4 or 5 degrees of each other -- that's a big difference from the last few months when #1 was noticeably hotter. And the number 1 exhaust gas temperatures were quite a bit below the other three. That's not much of a change.

We'll see if a flight later this week reveals any difference in temperatures but the engine is sounding better and better -- smoother -- to me than it has in quite awhile.
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
Last article: "Gonna Finish This Sucker" (Kitplanes)
Waiting for the avionics kit (backordered: chip shortage)

Last edited by LettersFromFlyoverCountry : 06-19-2012 at 09:04 PM.
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  #170  
Old 06-19-2012, 09:11 PM
SteinAir SteinAir is offline
 
Join Date: Feb 2005
Location: Minneapolis
Posts: 2,478
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Wow Bob, I feel like a proud papa....you're all grown up and pulling/cleaning injectors like you've been at it your whole life! Isn't this test period thing fun? Look at all the new skills you're acquiring! In all seriousness, well done and keep up the good work.

Cheers,
Stein
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