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  #31  
Old 06-03-2017, 08:54 PM
Azjulian Azjulian is offline
 
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Location: Scottsdale, Arizona
Posts: 130
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I unplugged my EGT lead prior to ensure that I could be a 100% on which lead was giving the higher reading.

I have to say I'm completely out of ideas now and seriously concerned that I am going to have a mechanical issue with this engine. I will strip the right carb as well. But this issue remains, has been present since flight 1.

I don't know anyone whose carbs I can swap out.

Personally I'm starting to think this is to do with the internals of the engine, a sticky valve sleeve at higher rpm for instance.

I built a plane with a brand new engine for a reason I didn't want to have to chase these issues. Has anyone gone the extra step in a situation like this and pursued a warranty claim ? How do I go about that ?
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  #32  
Old 06-03-2017, 10:58 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by rvbuilder2002 View Post
As I wrote in my other reply, if your static full throttle RPM is higher than your climb RPM then something is wrong. The flight RPM (even in a climb... should always be higher by at least a little bit but the actual difference depends on your climb speed)

As for your roughness issue, if 100LL did not solve it then the next thing I would recommend is inspect for debris in the carbs. It is somewhat common with a brand new build. Stuff can get flushed from the new hoses and lines into the carbs and often causes problems intermittently. It may even be in some way causing a slight power loss only in flight that is effecting your climb RPM.

Your max level RPM of only 5500 when the static is 5200 is another indicator that something is out of wack. A static of 5200 should cause a level full throttle to probably be above red line (5800)
Quote:
Originally Posted by Azjulian View Post
Scott - can I confirm your concern, from your message I'm reading that you would expect the static WOT RPM to be lower than the climb WOT RPM and then that cruise WoT RPM ?

We are just not seeing that here, I had a friend who has an SLSA RV12 check and his ground static WOT is 5500RPM, at 75knt climb out he is seeing between 53000 and 5350. Then in level flight WOT he gets 5600
Yes as indicated in my earlier post

More bad data I would guess because an RV-12 would be a horrible performer with a WOT static RPM of 5500. It is impossible to have a WOT static RPM of 5500 and level flight WOT of only 100 RPM more.

Doing a static RPM check with a wind blowing will give a false reading but to get a static of 5500 with a properly adjusted prop pitch would probable require the nose to be pointed into a 100 MPH wind so that is not likely the explanation.

Every RV-12 I have flown or worked on (at least a dozen I would guess) and every fixed pitch propeller RV I have ever flown or worked on has had a WOT static RPM that is lower than the WOT climb RPM. Basic physics makes that happen.
You are correct that the static RPM will be different from one day to another (or even time of day) because of the influences of air density, but the variation isn't typically very large unless you compare coldest day middle of the winter to warmest day, middle of the summer.
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Scott McDaniels
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RV-6A (aka "Junkyard Special ")
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  #33  
Old 06-04-2017, 05:07 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by Azjulian View Post
Personally I'm starting to think this is to do with the internals of the engine, a sticky valve sleeve at higher rpm for instance.
You are using Aero Shell Sport 4 Oil?

Did you do correct oil purge prior to first start so hydraulic lifters pump up?

At risk of getting yelled at here... Try adding Marvel Mystery Oil 2oz/5gallons to your fuel to add top-end lubricant for valve stems. MMO is synthetic and will pass through the engine without burning.
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 350

LSRM-A Certificate 2016
Special Thanks to EJ Trucks

Last edited by Piper J3 : 06-04-2017 at 05:11 AM.
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  #34  
Old 06-04-2017, 07:52 AM
Azjulian Azjulian is offline
 
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Location: Scottsdale, Arizona
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HinJim - yes that oil came with my engine, and I bought a new oil filter to replace the one that was on the engine when it shipped. I performed the oil purge procedure and tested each of the lifters as part of that procedure and they were all good.

It's interesting you mention that I was talking to a Rotax certified mechanic last night about coming to take a look at the engine next week. When I walked him through my symptoms he said that he had seen a sticky valve stem issue only surface at high RPM causing very similar symptoms....
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  #35  
Old 06-04-2017, 08:05 AM
Azjulian Azjulian is offline
 
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Scott - I understand exactly what you are saying and I wasn't there when friend tested so let's exclude that data. But what I can tell you with certainty and I'll post an image of the log (when I work out how to on this forum) that when I start my ground roll at WOT my rpm reading was 5170 (this is prior to adjusting pitch of my prop, I haven't flown since doing that), in my climb out (I did not touch my throttle, its pinned to the firewall) I see the rpm drop slightly and at the top it's 5070 and I can see in savvyanalysis it's been declining gradually. At top of my climb I level out still WOT and manage 5510.
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  #36  
Old 06-04-2017, 08:11 AM
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Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by Azjulian View Post
It's interesting you mention that I was talking to a Rotax certified mechanic last night about coming to take a look at the engine next week. When I walked him through my symptoms he said that he had seen a sticky valve stem issue only surface at high RPM causing very similar symptoms....
Sticking valve at high speed is a possibility. Aircraft engines typically use low force valve springs to reduce wear on cam lobes/lifter.

I use Marvel Mystery Oil at 2 oz/5 gallons about every tenth fill-up. Now at 230 hours with like-new performance.

Couldn’t hurt to give it a try…
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 350

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #37  
Old 06-04-2017, 08:11 AM
Azjulian Azjulian is offline
 
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Location: Scottsdale, Arizona
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Log of climbout


Last edited by Azjulian : 06-04-2017 at 08:20 AM.
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  #38  
Old 06-04-2017, 09:00 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Very odd indeed. Could be valve hanging up. What happens if climb to 2K and level at cruise power instead of longer climb to 4K?
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 350

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #39  
Old 06-04-2017, 09:07 AM
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Piper J3 Piper J3 is offline
 
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Try two tings...

1) Reduce climb rate - I can't tell from scale on your graph but appears to be near max 1000 fpm. So try slower climb with slightly reduced power - pull throttle back ~ 1" after initial climb is established. I Assume you are flying single-place and min fuel to stay lightly loaded.

2) Reduce power when you level off so engine stays 5000 rpm. Ok to let speed build slowly and not push over the top to gain speed.
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 350

LSRM-A Certificate 2016
Special Thanks to EJ Trucks

Last edited by Piper J3 : 06-04-2017 at 09:18 AM.
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  #40  
Old 06-04-2017, 09:17 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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I don't understand why both EGT's start going low in the climb. Maybe vacuum diaphragms that set fuel mixture based on altitude are working correctly. Maybe you have induced pressure or weird air flow in the cowling causing carbs to calibrate mixture incorrectly.

Do you have newest design where fiberglass plenum is no longer used to direct cooling air to cylinder fins?
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 350

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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