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  #11  
Old 03-13-2019, 09:24 PM
Jpm757 Jpm757 is online now
 
Join Date: May 2013
Location: Sherman, CT
Posts: 301
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Intake leak?
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Jake
RV6 completed 1991 sold.
RV7 #72018 N767T first flight 11/21/2017 200+ hrs.
IO-360M1B MT 3 blade, Dual AFS 5600.
1941 J3 Cub skis floats.
2019 dues gladly paid.
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  #12  
Old 03-13-2019, 10:00 PM
chrisbryanolsen chrisbryanolsen is offline
 
Join Date: Oct 2011
Location: Albuquerque
Posts: 84
Default Plugs?

Did you try switching some plugs around?

Good luck getting home!
You and Mer be safe.

ó G
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  #13  
Old 03-13-2019, 10:22 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Quote:
Originally Posted by Guy Prevost View Post
Problem appeared after ~30 minutes of flight after leaving Dallas and is present on both tanks! .
I would start with the smoking gun. Think real hard about what, if anything happened or you did in Dallas. I would also pull a can of gas out and take it to the FBO for a smell test against fresh gas. Did you check for water? The IO's can deal with water better than a carb'ed engine and will create roughness when they do injest it if well mixed.

If a station has water in their tank, it will get smashed into tiny particles by the pump as it goes into your plane. It can take quite a bit of time for it to settle out, so on a quick fuel stop that can be well after take off.

Larry
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RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress

Last edited by lr172 : 03-13-2019 at 10:27 PM.
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  #14  
Old 03-14-2019, 06:27 AM
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Guy Prevost Guy Prevost is offline
 
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Location: albuquerque, nm
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More good advice here. Iíll definitely be checking gas again. I filled up Sunday and didnít fly again until Wednesday, so there was plenty of time to settle.

A local mechanic I talked to last night suggested I think about how the environment is different from my normal operating environment. Obviously thereís the potential for water in gas, but thereís another one: Altitude!

I live at 6000í with warm temps. I always fly WOT. Yesterday I saw a high CHT On #3 at takeoff and mentally flagged a dirty injector (maybe wrong assumption). I then flew at partial throttle at 3500 feet, something I never do. An intake leak could cause both of those problems I experienced in those conditions. At takeoff and max power, just enough extra air to lean things out via the Venturi effect. Later at partial throttle thereís a pressure differential across a leaky gasket.

I Hope thatís all it is. Iím meeting the mechanic at 0830 to take a look. He seems like a reasonable sort.

Iíll potentially reposition and call Monkey if things get complex.
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Albuquerque, NM
RV-8a Built, Enjoyed, Sold
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RV-10, Bought, Rebuilt, Enjoying
Build / First Flight Video: http://www.youtube.com/watch?v=8f9HXzZT1dE
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  #15  
Old 03-14-2019, 07:11 AM
F1R F1R is offline
 
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IO 540 at 13000 ft I once had a vibration show up that acted and made me believe either bad fuel or a minute air leak at a fuel fitting somewhere. After extensive ground checking produced nothing, A few more flights finally revealed I had an electronic ignition failing.

A second mag was installed and only happy hours since.
Good Luck!
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  #16  
Old 03-14-2019, 07:36 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Quote:
Originally Posted by Guy Prevost View Post

I live at 6000’ with warm temps. I always fly WOT. Yesterday I saw a high CHT On #3 at takeoff and mentally flagged a dirty injector (maybe wrong assumption). I then flew at partial throttle at 3500 feet, something I never do. An intake leak could cause both of those problems I experienced in those conditions. At takeoff and max power, just enough extra air to lean things out via the Venturi effect. Later at partial throttle there’s a pressure differential across a leaky gasket.
During take off you should be at a near 0 vacuum level, regardless of altitude. Intake leaks are basically non-problematic at 0 vacuum and become progressively more problematic as vacuum increases. MAP doesn't correlate with vacuum well, due to the different altitudes we experience in airplanes.

I agree that ignition is a possible culprit here and I would be running, at cruise, on each individually to observe differences when running on one vs the other.

Larry
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Last edited by lr172 : 03-14-2019 at 07:40 AM.
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  #17  
Old 03-14-2019, 11:28 AM
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Guy Prevost Guy Prevost is offline
 
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Location: albuquerque, nm
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Default I think Iím all set!

Steve McLeod, a local A&P showed up with tools today. He was knowledgeable and willing to work with me, not just grumble about experimentals. I mostly needed access to tools, but he was far more useful than that and a good value too. I guess he maintains a few RVs around these parts.

We test ran with normal ignition checks etc. No issues. When I removed the upper cowling this time, I noticed the (relatively new and not well set) aft baffle seal was turned backwards. One of the things I had really noticed when the problem appeared yesterday was significant cowling vibration and extra pillowing between camlocks. The Mrs and I looked hard for a cowl problem because thatís what it felt like.

Intake gaskets were all good, but the intake tube from the sump on #3 was loose. They were all just re-swaged at engine rebuild 120 hours ago. Ugh. It wasnít loose enough to go anywhere; we repositioned so that its sitting well, cleaned and applied RTV. A temporary fix for sure.

I just finished flying .75. No roughness and all CHTs and EGTs normal. #3 CHT did not run up high like it had the last couple of takeoffs. Completely nominal. Climb to 6500 was normal. Flew high and low MP at different RPMs. No issues. Leaned to a about 35degrees LOP and did an ignition check. A slight change in tone and then smooth. All 6 EGTs slowly increased, but no roughness.

In my RV8 I found several issues the first few times operating out of lowland airports. I live at 6kí and mostly fly places that are as high or higher. My canopy skirt would buzz against the fuse at high IAS, something nerver achieved at home. On another trip, a wing root fairing let go. All of these items were associated with descents into near sea level airports. I think that the rear baffle seal either got flipped at cowling installation or that the increased pressure from high IAS (and pressure) descents into these high lowland airports flipped it.

Since I found solutions to both anomalies I was experiencing and canít reproduce them after those repairs, Iím headed 30 minutes South. There are lots of friendlys at GTU, but the best runway for todayís conditions is closed. EDC has a car waiting for me, and is closer to family so thatís the plan for now. Iíll report in later today.
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Albuquerque, NM
RV-8a Built, Enjoyed, Sold
Two Kids: Built, Enjoying
RV-10, Bought, Rebuilt, Enjoying
Build / First Flight Video: http://www.youtube.com/watch?v=8f9HXzZT1dE
Build Log: http://websites.expercraft.com/geprevo/

Arguing on the internet is like having a competition to see who can hit a brick wall the hardest. You may win, but you're still an idiot.
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  #18  
Old 03-14-2019, 05:32 PM
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Guy Prevost Guy Prevost is offline
 
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Weíre safe at EDC. The rear baffle seal flipping and vibrating against the upper cowling is confirmed. It happened again just prior to arrival. Visually verified the state before and after. Iíll have to fix it prior to going home, but weíre among friends and family. The cavalry is arranged for a better fix on Friday
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Guy Prevost
Albuquerque, NM
RV-8a Built, Enjoyed, Sold
Two Kids: Built, Enjoying
RV-10, Bought, Rebuilt, Enjoying
Build / First Flight Video: http://www.youtube.com/watch?v=8f9HXzZT1dE
Build Log: http://websites.expercraft.com/geprevo/

Arguing on the internet is like having a competition to see who can hit a brick wall the hardest. You may win, but you're still an idiot.
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  #19  
Old 03-14-2019, 09:27 PM
Mconner7 Mconner7 is offline
 
Join Date: Feb 2018
Location: Bradenton FL
Posts: 6
Default The RV community pitches in.

Great news,
As someone recently AOG with a trim issue, I too thank all the contributors to this forum for all the support. I love my RV and enjoy our family of flyers and builders.
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  #20  
Old Yesterday, 09:48 AM
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F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
Posts: 724
Default Fixed?

I'm 6mi N of EDC -plenty of parts here. Let me know if you still need help.

512.289.0746
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