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  #1  
Old 04-24-2016, 11:45 AM
Bayou Bert's Avatar
Bayou Bert Bayou Bert is offline
 
Join Date: Sep 2012
Location: Prairieville, LA
Posts: 223
Default CS Propeller Agony

My RV9A "Pearl" now has 13.9 flight hours in Phase I.
From the very first lift off, the prop has surged and was still
doing it yesterday when we flew.
Info on plane
Engine: O-320-D2G with FI
Starting Governor: MT P-860-4 and was not one in the batch with problems.
Prop: Hartzell C2YL-1BF/F7663-4

What has been done so far:
Governor
The governor was a new MT put on the engine when it was build.
When the problem started (first flight) I removed governor and sent to
MT in DeLand, FL. The replaced a spring and polished a shaft and said
the governor met MT requirements.
Re-installed and found no difference.
Then friend had a rebuilt Woodward which was installed.
No change on the RPMs surging.

Prop
Prop was purchased (rebuilt) for a Northwest coast prop shop in 2014.
When problems started, prop was removed and taken to a reputable prop
shop in the Houston area for a quick check. Static balance was off slightly
and corrected then on the bench, air applied and all angles etc checked.
When I left, prop met Hartzells specs.
Since then prop was dynamic balanced with final reading of .05.
The static stops on the prop are set so that at full power on the ground
RPMs show 2650/60. Two tacks, checked to be correct during prop
balance and found accurate.

First chart is the first 50 seconds of takeoff showing MAP in orange and
RPMS in Blue.
Software takes a shot of data twice each second so distance from dot
to dot is one half a second.
Notice the big sag, sure gets your attention on take off.
On All charts, RPM scale on left, MAP scale on right.



Second chart is at 3500' then setting up 25/25, then moving the throttle
around to see RPM response. Notice RPM does not go back to exactly 2500
between moves



Third chart shows later in flight at 2400 RPM and me reducing the throttle and the RPMs going up!



I am now to the point I don't know what to do next. This is taking a bunch
of the fun out of Phase I having to worry about the engine/prop all the
time. This is the first CS prop I have flown behind. The person who has
flown several flight for me is a 30+yr A/P, IA and has thousands of hours
in everything from Cubs to Gulfstreams and he says he never seen one
behave like this one.
Sooooo.....that's the story to this point.
ALL...comments, questions, suggestions more than welcome.
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RV-9A known as Pearl Sold
Donation Done for 2021
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  #2  
Old 04-24-2016, 12:33 PM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,666
Default

It takes a bit of effort, but my recommendation is that you do the leak-down test described in this SERVICE INSTRUCTION

The results of that test will allow you to confirm whether or not the problem is related to the engine or propeller. If not, then you know it is related to the gov.

I have seen this be an engine problem a couple of different times. One was because of a removable plug that was left out of the nose section of the engine case.
Anything that causes oil to leak from the nose bearing section of the engine at a higher rate than is expected can cause propeller / gov. problems.
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Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
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RV-6A (aka "Junkyard Special ")
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  #3  
Old 04-24-2016, 12:44 PM
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Scremm Scremm is offline
 
Join Date: Feb 2006
Location: Eliot, Maine
Posts: 83
Default

How is your oil pressure behaving? It may be helpful to see how the oil pressure behaves relative to the RPM and manifold pressure.
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N221Z RV8A Maine 600+ hrs
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  #4  
Old 04-24-2016, 01:11 PM
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Bayou Bert Bayou Bert is offline
 
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Location: Prairieville, LA
Posts: 223
Default Oil Pressure and RPM

Blue RPM Left Scale
Orange Oil Pressure Right Scale



I don't see a problem here but I am not trained in CS stuff.
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RV-9A known as Pearl Sold
Donation Done for 2021
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  #5  
Old 04-24-2016, 01:28 PM
kiwipete kiwipete is offline
 
Join Date: Oct 2007
Location: Birmingham United Kingdom
Posts: 436
Default Fine pitch stops

Bert

The first thing that stands out to me is the fine pitch stops need coarsening up. You shouldn't be able to get anymore than 2650 static rpm. This is causing the surge on takeoff, as the governor is not quick enough to catch the over speed. The props I've setup all required about 1 1/2 turns to coarsen.
If you go too far it's ok but you'll notice the rpm will increase slightly during the takeoff.
To check the static you either need to open the throttle rapidly to see the maximum rpm before the governor has time to catch up or adjust the governor speed to 2700 rpm then keep adjusting the fine pitch stops, on the hub,so that max static is 2650.
The second graph isn't that unusual. On my setup which has an MT governor and Hartzell prop, the rpm will change slightly if I increase or decrease Manifold pressure. More importantly if say you set 22 inches and 2400 rpm then increase or decrease the speed does the prop maintain approx 2400?
I think sometimes we get too hung up on a few rpm difference. Modern instruments are far more accurate than the old gauges where a needle was approx 100 rpm now we get excited about 10-20 rpm difference.

The third graph I'm not sure about. How rapidly are you closing the throttle? It looks like the governor is trying to compensate but over shooting.

I hope this makes sense

Peter
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  #6  
Old 04-24-2016, 01:38 PM
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Jerry Cochran Jerry Cochran is offline
 
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Location: Sherwood, Oregon
Posts: 981
Default Gov line to prop?

It would take very little time to remove that line and verify no obstructions there or in the prop inlet.

From the above I would think one could rule out the governor itself since you've had same results with two different ones.

Might also be good to verify crank plugs are proper. More work tho...

Good luck,

Jerry
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RV-7a 707DD Bot from David Domeier 12/01/11
Lycoming IO-360 Catto 3 blade Panel upgrade in progress

RV6a 18XP 1st flite 03/21/07 sold to Dale Walter 10/22/2011
Superior IO-360, Hartzell Blended, GRT/Dynon

Happily "autopaying" DR

"Suppose you were an idiot, and suppose you were a member of Congress; but I repeat myself."

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  #7  
Old 04-24-2016, 02:49 PM
scsmith scsmith is offline
 
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Location: Ashland, OR
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Quote:
Originally Posted by Jerry Cochran View Post
It would take very little time to remove that line and verify no obstructions there or in the prop inlet.

From the above I would think one could rule out the governor itself since you've had same results with two different ones.

Might also be good to verify crank plugs are proper. More work tho...

Good luck,

Jerry
I was going to suggest this too. A kink in the line? any kind of obstruction? Too small a diameter? Do you have the approved Lycoming stainless steel line?
The other item to check seriously is what Scott suggested -- look at the arrangement of plugs in the nose of the crankshaft. If you are confused about what plugs should be in or out, get an A&P to help you.
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RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
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also
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  #8  
Old 04-24-2016, 03:00 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
Posts: 2,643
Default Prop

Not only check the oil line but the fittings at both ends for restrictions. I doubt if the crank plugs are the cause unless the rear plug is leaking.
Excessive clearance on the front main bearing could cause this issue. I have seen this on a newly overhauled engine.
All other alternatives should be eliminated first as a front main bearing problem is a complete engine teardown.
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  #9  
Old 04-24-2016, 03:24 PM
cajunwings cajunwings is offline
 
Join Date: Jun 2007
Location: new iberia la
Posts: 869
Default Prop Surging

This engine has the rear crank plug installed and for now has the flexible oil line installed (also approved)

Don Broussard

RV 9 Rebuild in Progress
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  #10  
Old 04-24-2016, 06:37 PM
scsmith scsmith is offline
 
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Location: Ashland, OR
Posts: 2,973
Default

I wonder if there could be elastic compliance in the flex line?
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Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 700
also
1/4 share in 1959 C-182B (tow plane)
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2020
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