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  #101  
Old 08-24-2016, 04:59 PM
vic syracuse vic syracuse is offline
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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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  #102  
Old 08-24-2016, 10:52 PM
Kellym Kellym is offline
 
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Quote:
Originally Posted by Weasel View Post
Without the SB31 being published how do you know it needs to be done? Are you aware that maintenance induced failures are a reality?
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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  #103  
Old 08-24-2016, 11:01 PM
Kellym Kellym is offline
 
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Quote:
Originally Posted by vic syracuse View Post
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
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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  #104  
Old 08-25-2016, 05:35 PM
vic syracuse vic syracuse is offline
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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
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  #105  
Old 08-25-2016, 05:45 PM
Bavafa Bavafa is offline
 
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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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  #106  
Old 08-25-2016, 05:47 PM
bcondrey bcondrey is offline
 
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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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  #107  
Old 08-25-2016, 09:11 PM
Kellym Kellym is offline
 
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Quote:
Originally Posted by bcondrey View Post
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.
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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  #108  
Old 08-26-2016, 04:00 PM
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GaryK GaryK is offline
 
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Sent you a PM

Thanks
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  #109  
Old 08-26-2016, 07:07 PM
rv4bill rv4bill is online now
 
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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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  #110  
Old 08-26-2016, 07:35 PM
woxofswa woxofswa is offline
 
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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.
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Last edited by woxofswa : 08-26-2016 at 07:40 PM.
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