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08-24-2016, 04:59 PM
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Super Moderator
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Join Date: May 2005
Location: Locust Grove, GA
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I confirmed the governor model as being correct with the chief inspector for MT-USA. Yes, I know there seems to be lots of conflicting data. But there sure are a lot of them flying for it to be the wrong one.
My guess on this, and it is ONLY my guess, is that they made a change in the manufacturing/assy process during a specified timeframe and have probably seen enough data from the overhauls to affect a SB once these flight failures occured. That might explain why they can act on an SB so fast without having seen the actual failures.
Vic
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 Vic Syracuse
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
Kitplanes "Unairworthy" monthly feature
EAA Sport Aviation "Checkpoints" column
EAA Homebuilt Council Chair/member EAA BOD
Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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08-24-2016, 10:52 PM
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Join Date: Aug 2005
Posts: 97
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Quote:
Originally Posted by Weasel
Without the SB31 being published how do you know it needs to be done? Are you aware that maintenance induced failures are a reality?
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I emailed Peter Marshall, manager of MT-USA, and he replied that my governor was on the internal tentative service bulletin and advised that I send it in.
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Kelly McMullen
A&P/IA
EAA Tech Counselor
KCHD
RV-10 40866
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08-24-2016, 11:01 PM
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Join Date: Aug 2005
Posts: 97
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Quote:
Originally Posted by vic syracuse
I confirmed the governor model as being correct with the chief inspector for MT-USA. Yes, I know there seems to be lots of conflicting data. But there sure are a lot of them flying for it to be the wrong one.
My guess on this, and it is ONLY my guess, is that they made a change in the manufacturing/assy process during a specified timeframe and have probably seen enough data from the overhauls to affect a SB once these flight failures occured. That might explain why they can act on an SB so fast without having seen the actual failures.
Vic
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My question is why Lycoming and MT literature show different gear ratios for wide and narrow deck engines IF all P-860 governors are the same except for clocking? Clearly the gear ratio does differ between dash numbers, with the gear shown on the dash 3 model matching the gear ratio for narrow deck engines. Clearly the gear ratio on the -5 and -19 match that called for on wide deck engines.
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Kelly McMullen
A&P/IA
EAA Tech Counselor
KCHD
RV-10 40866
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08-25-2016, 05:35 PM
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Super Moderator
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,626
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I can only take their word for it. My guess is that the P-860-3 can be adjusted for a wider RPM range.
Vic
__________________
 Vic Syracuse
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
Kitplanes "Unairworthy" monthly feature
EAA Sport Aviation "Checkpoints" column
EAA Homebuilt Council Chair/member EAA BOD
Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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08-25-2016, 05:45 PM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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I received a response from MT and in addition to what they have previously said and posted here, they added this :
The different between -3 and -4 is the gear ratio .
-3 has an gear ratio of 0,895:1 and -4 has an gear ration of 0,866:1
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Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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08-25-2016, 05:47 PM
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Join Date: Jan 2005
Location: Bellevue, NE
Posts: 524
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Seems like the subject of compatibility of the MT governors comes up every year or two. Several years ago I researched this same subject because of the single model being sold by Van's. I don't have the references now but the explanation was that the difference in the models was clocking of the arm AND how the max RPM adjustment (stop screw) were set from the factory.
FWIW, you see the same thing on Lycoming engines... An IO-540-D4A5 is identical to an IO-540-C4B5 in the parts book. Only difference is the RPM and HP rating. The C4B5 is rated at 250 HP @ 2575 RPM and the D4A5 is rated at 260 RPM @ 2700 RPM.
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Bob
RV-10 builder x2
RV-7A under construction
EAA Tech Counselor
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08-25-2016, 09:11 PM
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Join Date: Aug 2005
Posts: 97
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Quote:
Originally Posted by bcondrey
Seems like the subject of compatibility of the MT governors comes up every year or two. but the explanation was that the difference in the models was clocking of the arm AND how the max RPM adjustment (stop screw) were set from the factory.
FWIW, you see the same thing on Lycoming engines... An IO-540-D4A5 is identical to an IO-540-C4B5 in the parts book. Only difference is the RPM and HP rating. The C4B5 is rated at 250 HP @ 2575 RPM and the D4A5 is rated at 260 RPM @ 2700 RPM.
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Correct Bob.
I went back to my Matronics archives for explanation by the late Jim Ayers, an MT distributor, dba Less Drag Products:
"The -3 and -5 governors are identical, except for the final adjustments.
For the -3 governor on the wide deck IO-540 engine, the high RPM stop screw has to be turned out quite a bit to get to 2700 RPM from the factory setting of about 2550 RPM. (For the narrow deck IO-540 engine, the initial stop setting on the -3 governor would be at about 2700 RPM.)
The -3 governor on a wide deck IO-540 now has a longer travel to get to the low RPM stop. The governor arm should have full travel from the high RPM stop to the low RPM stop.
Perhaps someone already flying can say if they have full travel (stop to stop) available with Van's governor cable.
Full governor arm travel is helpful to have for the mag check so it is possible to get the expected 450 RPM drop when the governor/propeller is cycled.
Jim Ayers"
With the -5 on my wide deck I only had to move the arm to match the cable approach angle.
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Kelly McMullen
A&P/IA
EAA Tech Counselor
KCHD
RV-10 40866
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08-26-2016, 04:00 PM
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Join Date: Nov 2005
Location: Zeeland, Michigan
Posts: 398
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Myron
Sent you a PM
Thanks
Gary
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08-26-2016, 07:07 PM
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Join Date: Jan 2008
Location: orlando
Posts: 187
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Got the rocket apart for annual and looked at PG serial number.
MT Govenor
Hartzell CS
P-860-3 11g424-g09/11
I'm only a few numbers away from one that failed.
Narrow deck IO 540 C4b5
9.0 to 1 Pistons.
Bendix mags
Guess I'm grounded or at least soon to be when the SB comes out next week🙁
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Bill Whidden
52FA email for permission to land 
Harmon Rocket 11 Flying
Super Explorer Flying
bwhidden@totallymod.com
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08-26-2016, 07:35 PM
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Join Date: Sep 2007
Location: Mesa Arizona
Posts: 608
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Yeah my sticker says 10/11 but my engraved data plate says 9/11 so I would concur that you are at ground zero. Probably same production run. Probably same shipment. Which ultimately may or may not mean anything. This huevada is taking more twists and turns than a Clancy novel.
__________________
Myron Nelson
Mesa, AZ
RV-10 N24EV
KITPLANES Contributing Editor
Last edited by woxofswa : 08-26-2016 at 07:40 PM.
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