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MT P860-3 Prop Gov fail.

The arm is only needed for the quadrant. The arm allows you to use the full range in the quadrant. If you are using the Vernier controls, there isn't a race for the control to move in and look awkward - so no need.
 
Hartzell Governor Install

After about 5 hours of work I actually got it installed and working with the standard arm. This is what I had to do to install it:

1. With the existing washer, lock washer and nut I found the case studs were too short. I ended up using only the lock washer and nut and the stud is flush with the top of the nut. I will order new longer studs from Lycoming and change them next time I change the oil.

2. After loosening the nut holding the standard arm and re clocking it to the correct orientation I found the rod end would interfere with the travel stops. The Hartzell instructions say that you can loosen the cap screws and only rotate it withing the slot. After a lot of frustration and a visit to CharlieWaffles RV-10 I ignored the instructions and removed all the cap screws and rotated that cap assembly about 100 degrees. With the stop assembly now located in the back (like the MT) I was able to get it to work without any interference.

3. I then had to do a lot of trimming on the baffle assembly so that it would mount around the larger governor.

4. I then had to do a lot of trimming on the upper cowl fiberglass to get it to fit around the new governor.

It would be nice if the Hartzell governor purchased from Van's for an RV-10 came with the longer arm and was already clocked at the correct location. I suspect that the Van's tech support people are going to get a lot of calls.

Rob Hickman
N402RH RV-10
 
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After It would be nice if the Hartzell governor purchased from Van's for an RV-10 came with the longer arm and was already clocked at the correct location. I suspect that the Van's tech support people are going to get a lot of calls.

Rob Hickman
N402RH RV-10

It was brought to their attention at least four years ago when they started shipping the Hartzell governors.

Like the ring gear change causing alternator alignment issues, it's fallen on deaf ears. Like the alternator mount kit, this arm should be included in the FWF kit since you can't get airworthy without them.
 
It was brought to their attention at least four years ago when they started shipping the Hartzell governors.
Like the alternator mount kit, this arm should be included in the FWF kit since you can't get airworthy without them.

I slightly disagree. It should be included with the Quadrant kit option. As pointed out in previous posts, the arm shipped works with push-pull blue knobs. At least it did on mine, shipped fall 2009. (note 7 years ago)
Maybe a few instructions would have been nice. Like others, I stared at the thing a long time, finally contacted Hartzell, who said removing all the cap screws and rotating the top was okay if done carefully. Actual job was only a few minutes.
 
BTW, a post on the 'other' forum from someone who called MT in Germany says that MT has identified an issue and will be issuing a SB shortly.
 
My RPM at moment of PG Failure



FYI to Hartzell buyers

Van's lists their Hartzell govs incorrectly in their catalog. They list them as for "IO" or "O". According to Hartzell, there is no difference on fuel delivery. The correct listing should be for narrow deck or wide deck.

Rob,

Our meatball field mods to get back flying had us cutting the upper cowl opening enlargement with the saw blade of a Leatherman.
 
SB 31

I have just heard back from MT in Germany.

There is soon to be a new SB31 with expanded serial numbers to address the recent failures.

Although this will mean grounding my aircraft,cudos to MT for responding so quickly.

Letter below:

But we have another issue with the P-8XX-3 series , during operation a flyweight assembly could become loose.
In this case the damaged flyweight assembly will result in an overspeed or underspeed condition .

Shortly we will release the SB 31 because of that issues.
According this SB 31 your governor with the S/N 11G028G is affected .

This modification is free of charge.

If you have any more question , do not hesitate to contact me.


Best Regards

Andreas Seperant

Engineering / Tech Support
MT-Propeller Entwicklung GmbH
Airport Straubing-Wallmuehle
D-94348 Atting - GERMANY
phone: +49( 0 )9429-9409-44
fax: +49( 0 )9429 - 8432
www.mt-propeller.com
 
In looking more closely at my recorder data on www.savvyanalysis.com,there is something that stands out to me.

Prior to my PG failure, there were four momentary upward spikes in my RPM of approx 150RPM each. There were none on the previous segment of the flight, nor on the previous flight.

The first one happened 17 minutes prior to the failure. They are just blips with no duration at the peak. I honestly didn't notice them in the flight.
I am not expert on any of this stuff, and just started with the software, but, If I were to be in a situation where I was going to fly with one of these PG's, I would set my max RPM alert to 100 rpm higher than what I planned to use at cruise. (I normally cruise at 2300 below 10K and 2400 above).

One could do it prior to flight and just deal with the alert on takeoff, or reset the alert level once established in cruise. At any rate, it could give an alert that something is potentially wrong and give more time to GYAOTG
 
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Update on my Governor

After about 5 hours of work I actually got it installed and working with the standard arm. This is what I had to do to install it:

1. With the existing washer, lock washer and nut I found the case studs were too short. I ended up using only the lock washer and nut and the stud is flush with the top of the nut. I will order new longer studs from Lycoming and change them next time I change the oil.

2. After loosening the nut holding the standard arm and re clocking it to the correct orientation I found the rod end would interfere with the travel stops. The Hartzell instructions say that you can loosen the cap screws and only rotate it withing the slot. After a lot of frustration and a visit to CharlieWaffles RV-10 I ignored the instructions and removed all the cap screws and rotated that cap assembly about 100 degrees. With the stop assembly now located in the back (like the MT) I was able to get it to work without any interference.

3. I then had to do a lot of trimming on the baffle assembly so that it would mount around the larger governor.

4. I then had to do a lot of trimming on the upper cowl fiberglass to get it to fit around the new governor.

It would be nice if the Hartzell governor purchased from Van's for an RV-10 came with the longer arm and was already clocked at the correct location. I suspect that the Van's tech support people are going to get a lot of calls.

Rob Hickman
N402RH RV-10


Update on my Hartzell Governor change:

Van's sells two different Hartzell governors for the Lycoming 540 engine, listed as one for the IO-540 and one for the O-540. This is not correct! They should be listed as one for the wide deck engine and one for the narrow deck engine.

The Van's Hartzell IO-540 governor should be labeled Wide deck 540 and the O-540 should be labeled narrow deck 540.

The good news is that after installing my second Hartzell governor in 24 hours it worked perfect. The prop RPM on takeoff was 2700 with the factory adjustment and cruise RPM is very stable. I have about 3 hours on the new governor and it looks like the Hartzell governor does a better job of holding RPM.

Rob Hickman
N402RH RV-10
 
Thanks Rob, I've posted that too. I found out about the catalog glitch from Hartzell tech support who expressed that for a while they have wished Van's would both correct the listings and list the exact Hartzell part number as well.

I have passed the message to Scott R and he said he would look into it.
 
Thanks Rob, I've posted that too. I found out about the catalog glitch from Hartzell tech support who expressed that for a while they have wished Van's would both correct the listings and list the exact Hartzell part number as well.

I have passed the message to Scott R and he said he would look into it.

I got an email from Van's yesterday confirming the "O" model is for the narrow deck 540 and the "IO" model is for the wide deck 540. They also stated that they plan to discontinue selling the "O", narrow deck model as the D4A5 engines they sell are wide decks.
 
I have just heard back from MT in Germany.

There is soon to be a new SB31 with expanded serial numbers to address the recent failures.

Although this will mean grounding my aircraft,cudos to MT for responding so quickly.

Letter below:

But we have another issue with the P-8XX-3 series , during operation a flyweight assembly could become loose.
In this case the damaged flyweight assembly will result in an overspeed or underspeed condition .

Shortly we will release the SB 31 because of that issues.
According this SB 31 your governor with the S/N 11G028G is affected .

This modification is free of charge.

If you have any more question , do not hesitate to contact me.


Best Regards

Andreas Seperant

Engineering / Tech Support
MT-Propeller Entwicklung GmbH
Airport Straubing-Wallmuehle
D-94348 Atting - GERMANY
phone: +49( 0 )9429-9409-44
fax: +49( 0 )9429 - 8432
www.mt-propeller.com


Wonder if sending it back to comply with the SB will also reset the 2000 hour/72 month overhaul clock?

Any mention of that?

I have one of the P-8XX MT governors, and am waiting to see the new SB to see if my serial number is in the affected group...my unit will be up against the calendar limit next year.

If I have to send it back due to the SB, I'm not wanting to pull the thing off twice in 6 months...once for this and again for the overhaul...I want to get it all done at once.

It would be good of MT if (as part of the fix) it does reset the overhaul clock...worth the hassle of having to pull it off in the first place, then.
 
Thanks Rob, I've posted that too. I found out about the catalog glitch from Hartzell tech support who expressed that for a while they have wished Van's would both correct the listings and list the exact Hartzell part number as well.

I have passed the message to Scott R and he said he would look into it.

My understanding is that the O and IO designations were based on information originally provided by someone at Hartzell (since Van's doesn't have an airplane with a narrow deck there would be now way to personally know).

I am also not aware of Hartzell going beyond wishing, and actually tell anyone that the designation was incorrect.

(but I could be wrong)
 
Scott, no disrespect to you or Van's, which I consider to be the cream of the crop, but I was told that the reason Van's originally sent the narrow deck versions to everybody and was telling them to just reclock them is that the prototype originally had a narrow deck engine. Maybe that is just urban legend. It doesn't really matter.

This avocation has a foundation of new stuff learned everyday. Nobody expects anyone to know everything.
 
Scott, no disrespect to you or Van's, which I consider to be the cream of the crop, but I was told that the reason Van's originally sent the narrow deck versions to everybody and was telling them to just reclock them is that the prototype originally had a narrow deck engine. Maybe that is just urban legend. It doesn't really matter.

This avocation has a foundation of new stuff learned everyday. Nobody expects anyone to know everything.

The difference between the wide deck and narrow deck version is the pressure output because the two engines have different gear ratios for the gov drives.

That is the reason for two different gov.

Not already having the correct clocking is is unrelated. The manufacturers will set it to what every you desire but it is not practical to stock a bunch of different parts just for different clocking positions, when they can (relatively) easily be changed.

Not urban legend, but not true.
N410RV still has the same engine it had since first built, and it is the same wide deck engine that Van's currently sells to RV-10 builders.
 
P860-3.

Nobody answered this one, so I try again.
Does the MT P860-3 governor work on both wide and narrow deck IO-540's?
Thanks
Johan
 
Even more confused now!!

Vans sells P860-3 for IO-540 engine that they sell, which is a wide deck engine.
Per MT application page http://www.mt-propeller.com/pdf/list_gov_e-1057.pdf
P860-3 is for Lyc IO-360-( ) front mounting, ratio 0.895:1 (top of page 2)
P860-19 is for Lyc IO-540, specifically RV10 mentioned, ratio 0.947:1 (middle page 2), with prop MTV-12-B
P880-21 for Lyc IO-540 (n. deck), ration 0.895:1. (bottom page 4)
P884-3 for IO-540 narrow deck, ratio 0.895:1, (bottom page 5)
P884-5 for IO-540 wide deck, ratio 0.947:1. (top page 6)
P884-20 Lyc IO-540- wide deck, ratio 0.947:1. (4 lines down page 6)
These are all RIGHT hand rotation facing the driving pad (which I assume to be clockwise rotation).
All of these except for the RV10 does not have an aircraft type mentioned.
All of these other than the RV10 does not have a propeller mentioned.
I have not seen a front mounted governor on IO-360, but I am no expert on that.
It seems to me that the P860-3 has the correct ratio for the narrow deck engines. Yet VANS sells it for the wide deck engines that they sell.
Hope someone has more insight into this than I have.
Johan
 
Governor RPM

Per MT website the max RPM for P-860-3 is 2420+/- 10. Engine spinning at 2700 with 0.895:1 ratio (narrow deck) will give this gov RPM.
Engine spinning 2700 RPM with gov ratio of 0.947:1 (wide deck) will have gov RPM of 2557 (range 2557+/-10).
If this is correct then using P860-3 on wide deck engine will result in over speed. Could this have resulted in the mechanical failures of governors not covered by previous SB?
Were the engines on which the failures occurred wide or narrow decks?
Just wondering. Might be completely off.
Johan
 
Per MT website the max RPM for P-860-3 is 2420+/- 10. Engine spinning at 2700 with 0.895:1 ratio (narrow deck) will give this gov RPM.
Engine spinning 2700 RPM with gov ratio of 0.947:1 (wide deck) will have gov RPM of 2557 (range 2557+/-10).
If this is correct then using P860-3 on wide deck engine will result in over speed. Could this have resulted in the mechanical failures of governors not covered by previous SB?
Were the engines on which the failures occurred wide or narrow decks?
Just wondering. Might be completely off.
Johan

My engine was a Narrow Deck
 
Mine was narrow deck as well. One thing this incident has reinforced to me is that incidents almost never have a single point of failure, but are an accumulation of multiple Ernie Gann-esque events of fate and/or folly that culminate into a fail.
Thankfully nobody got hurt and hopefully we can purge this demon from our ranks.

It's still too early IMHO, to make a definitive final determination of what is going on, but in the meantime, EVERYBODY, wide or narrow, 360 or 540, needs to verify that they have the proper unit for their configuration regardless of receipts, catalog listings, kit inventory, or how perfectly it appears to be operating at the moment. An engine builder told me that he was going to "do his part" by attaching a "big *** placard" to every engine shipped from now on, concerning the PG appropriate for that engine.
We are a community of humans and humans make mistakes, but hopefully we learn from them and move on with a broader safety envelope. Manufacturers need to reevaluate their documentation and what they are shipping out and what their vendors are doing with them. Venders need to know what they are stocking, recommending, and supplying to their customers, builders need to know what their exact needs are, and tech advisors, DARS, and mechanics need to be keenly aware of gotchas. Trust but verify.
 
I called MT-USA yesterday and talked a while. There is no differance in any of the P-860-XX governor parts. They all have the same weights, springs, drive rotation, etc and are for pressure to increase pitch props (non-counterweighted). The dash number is for the clocking of the actuator arm position which can be changed in the field, and for the maximum RPM speed whitch also can be changed by a certified shop...he told me how its done and its not rocket science. So as long as if it is set to hold ~ 2700 RPM at max pitch it will work. If not a few changes will make it work. My gov. was set to hold the correct RPM when I installed it new right out of the box. This is why van does not stock a lot of different governors. They can be modified to work on many different applications. He even said the max RPM can be changed some by changing the stop set screw in the field.
 
Did MT indicate when they are going to release the new Service Bulletin with the expanded listing and scope of affected units?

Sometime this week? This month?

I'm not flying the aircraft until I do or do not know if I have a governor with a problem and what the planned SB release date would be nice to know for those of us that have taken this step.

I'm trying to hold off on being 1 of 10,000 calls lighting up their phone system inquiring about it...if the info is going to be put out pretty soon.

Nothing on any of their websites so far...

Thanks.
 
Data point

Per MT website the max RPM for P-860-3 is 2420+/- 10. Engine spinning at 2700 with 0.895:1 ratio (narrow deck) will give this gov RPM.
Engine spinning 2700 RPM with gov ratio of 0.947:1 (wide deck) will have gov RPM of 2557 (range 2557+/-10).
If this is correct then using P860-3 on wide deck engine will result in over speed. Could this have resulted in the mechanical failures of governors not covered by previous SB?
Were the engines on which the failures occurred wide or narrow decks?
Just wondering. Might be completely off.
Johan

A 10 friend ordered his engine (new wide deck) and MT gov from Vans. First flight in May. The RPM was ~200 rpm low. 2500ish RPM. RPM should be checked on first flight, or before.
 
A 10 friend ordered his engine (new wide deck) and MT gov from Vans. First flight in May. The RPM was ~200 rpm low. 2500ish RPM. RPM should be checked on first flight, or before.

There is however no problem operating the -10 with 2500RPM I have to do this due to noise restriction as standard since Sept. 2013. Max RPM should be checked before first flight like high speed taxing.

Regards
Michael
 
I received this correspondence from MT this morning, FWIW:

Thank you very much for your message and information.

As fast as possible we will release SB31.

The reason for SB31 is that during operation a flyweight assembly could became loose

The damaged flyweight assembly will result in an overspeed or underspeed condition.



Affected are all governors which are manufactured between April 2010 until July 2013 and which are installed on experimental direct drive engines modified with electronic ignition and /or higher compression piston.



So your governor has the S/N 14G095-G (Manufacturing year 2014) is not affected from SB 31. You can go on with flying.

If you have any more question do not hesitate to contact me.

Best Regards

Andreas Seperant

Engineering / Tech Support

MT-Propeller Entwicklung GmbH

Airport Straubing-Wallmuehle

D-94348 Atting - GERMANY

phone: +49( 0 )9429-9409-44 <tel:%2B49%28%200%20%299429-9409-44>

fax: +49( 0 )9429 - 8432 <tel:%2B49%28%200%20%299429%20-%208432>

www.mt-propeller.com <http://www.mt-propeller.com>
 
Mine was also a BPE narrow deck that states "built to D4A5 specs".

I chose low compression 8.5 cylinders over future fuel concerns. I wanted a cruise motor, not a race motor. Data plate states 260 hp.

I seem to recall an issue years ago where Van's was shipping "narrow deck" PG's to wide deck owners who were being told to simply change the clocking.

Bendix 1200's for me.

Nope--Slick retard breaker mag with Slickstart on the left, Slick plain on the right

I received this correspondence from MT this morning, FWIW:

Thank you very much for your message and information.

As fast as possible we will release SB31.

The reason for SB31 is that during operation a flyweight assembly could became loose

The damaged flyweight assembly will result in an overspeed or underspeed condition.



Affected are all governors which are manufactured between April 2010 until July 2013 and which are installed on experimental direct drive engines modified with electronic ignition and /or higher compression piston.



So your governor has the S/N 14G095-G (Manufacturing year 2014) is not affected from SB 31. You can go on with flying.

If you have any more question do not hesitate to contact me.

Best Regards

Andreas Seperant

Engineering / Tech Support

MT-Propeller Entwicklung GmbH

Airport Straubing-Wallmuehle

D-94348 Atting - GERMANY

phone: +49( 0 )9429-9409-44 <tel:%2B49%28%200%20%299429-9409-44>

fax: +49( 0 )9429 - 8432 <tel:%2B49%28%200%20%299429%20-%208432>

www.mt-propeller.com <http://www.mt-propeller.com>

Anyone care to venture why they mention electronic ignition and high compression. The failures here do not support the remark.
 
Unfortunately, I have to agree, Weasel. It's not making any sense to me right now, and hasn't for the last week. First, I think the data field for the failures is kind of low---yes, they might be from a close-timeframe batch, but there sure is a large time-in-operation spread between them. For piece of mind for me in the meantime I am changing the governor to a PCU5000X (I was going to use a Hartzell, but got the wrong one shipped from Van's last week). I currently have about 1100 hours on my P-860-3, and had it overhauled at 950 hours.
Something must have changed in the manufacturing process for the MT governors, and I hope we can find out soon.

BTW, the The P-880 governor someone mentioned in an earlier thread is for a counterweighted prop. The P-860-3 is the correct model for the RV-10.

Vic
 
Anyone care to venture why they mention electronic ignition and high compression. The failures here do not support the remark.

It's a head scratcher. Besides having only mags (as already noted), I have stock 8.5 low compression pistons.

I'm still curious as to how they are able to come out with an SB and a fix so fast being that outside of external pics they have not examined either Myron's nor my PG.
 
It's a head scratcher. Besides having only mags (as already noted), I have stock 8.5 low compression pistons.

I'm still curious as to how they are able to come out with an SB and a fix so fast being that outside of external pics they have not examined either Myron's nor my PG.

Well, hopefully this information will get back to them before they actually publish the SB.
 
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It's a head scratcher. Besides having only mags (as already noted), I have stock 8.5 low compression pistons.

I'm still curious as to how they are able to come out with an SB and a fix so fast being that outside of external pics they have not examined either Myron's nor my PG.

Perhaps you three are not the only failures.
 
Vic,
Is the PCU5000 the same form factor as the MT. I have the Sam James cowl and plenum so the PG cylindrical shape is important unless I modify the plenum.

Thanks
Gary
 
Perhaps you three are not the only failures.

My thoughts as well, although you would think that multiple failures would be relatively common knowledge--perhaps not. However, methinks that something was already in the works based upon some kind prior knowledge, especially since the SB is apparently going to target only a specific manufacturing date range of the model and not all of them.
 
I have scoured the Internet and can't find any other failures, which I find hard to believe.

I will le tyou know on the form factor.

Vic
 
This gets more confusinger by the day. I dug deep into my documents and there is a card (mostly in German), that says that the 860-3 is specified for 360
Series engines and 2500 RPM.

I've had supposed experts say that the ratio difference of WD and ND is a big huge ticking bomb deal and others say that it is very minor that all it does is slightly vary the speed of the pump and slightly change the distance throw of the arm to make a given change. I've heard of a well known pilot who purposely runs a ND ratio pump on his WD because he likes the feel better and had never had a
problem. The external gear on my failed unit is in pristine condition.

I emailed MT, sent my pictures, and offered any help I could and they never answered me back.
 
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Unfortunately, I have to agree, Weasel. It's not making any sense to me right now, and hasn't for the last week. First, I think the data field for the failures is kind of low---yes, they might be from a close-timeframe batch, but there sure is a large time-in-operation spread between them. For piece of mind for me in the meantime I am changing the governor to a PCU5000X (I was going to use a Hartzell, but got the wrong one shipped from Van's last week). I currently have about 1100 hours on my P-860-3, and had it overhauled at 950 hours.
Something must have changed in the manufacturing process for the MT governors, and I hope we can find out soon.

BTW, the The P-880 governor someone mentioned in an earlier thread is for a counterweighted prop. The P-860-3 is the correct model for the RV-10.

Vic

Vic,

Thank you for the post. It helps validate the decision I made.

The MT P860-4 on my RV-8 was due to be sent back for the six year inspection/rebuild... MT quoted me $800.00 for the service and indicated a two week turn around.

After reading about the MT prop governor issues you all were having on the RV-10's (MT P860-3) I decided to ground my plane, remove the MT PG and apply the $800 dollars I would have spent on the MT PG rebuild towards a brand new PCU-5000X from Aero.

Aero sold me a new PCU5000X for $1,200, comes with a warranty and isn't due for a rebuild for 72 months. Should have a new one in five days. It seemed the prudent way to go.

To those of you who have had PG failures. Good job getting your planes safely on the ground. Best wishes in your resolving your problem at the lowest possible expense. Most of all, thank you very much for sharing your experiences with us.
 
Vic,
Here are a few pics of the "form factor" I was asking about. For some reason the second pic is upside down (looking in the cowl inlet)

Thanks
Gary

2eebo1t.jpg
[/IMG]

34oc7j9.jpg
 
This gets more confusinger by the day. I dug deep into my documents and there is a card (mostly in German), that says that the 860-3 is specified for 360
Series engines and 2500 RPM.

I've had supposed experts say that the ratio difference of WD and ND is a big huge ticking bomb deal and others say that it is very minor that all it does is slightly vary the speed of the pump and slightly change the distance throw of the arm to make a given change. .

It is clear that the P-860-3 will work on both the wide and narrow deck engines. It is also clear that it has the gear ratio specified for the narrow deck. The rpm specified is for the governor, not engine rpm, so 2700 times the gear ratio give. s you the governor rpm.
What is not clear is why Vans chose this version, when they have always sold wide deck engines, and the P-860-5 has the correct gear ratio for that engine. Also, MT's application document recommends a P-860-19 for the RV-10 with an MT 12B prop. Don't know anything about that version of the governor.
My P-860-5 is going back to MT today to have the SB31 done on it.
 
Does any one know the difference between a P860-4 and P860-3. I just looked up my paperwork and it indicates I have a P860-4
 
Juergen from MT USA told me today that all P-860 are the exact same except for the clocking. He said he doesn't understand why MT does it that way, because it is very confusing.

This came up, because I asked him why the MT applicability chart shows the P-860-19 as the appropriate PG for the IO-540-D4A5, but MT sold me the -3.

Also, the SB has now been pushed back to Monday next week.

Please don't shoot the messenger here. I am only parroting what I was told an hour ago by MT. I am not a PG expert and barely have an idea of how the dang things work.
 
I confirmed this week that the P-860-3 is the correct governor.

Vic

Can I ask who confirmed that and for what application? I'm at the point where three experts have four opinions on the matter. Not literally, but I'm definitely stuck right on top of the VOR if you catch my azimuth.
 
Service interval?

I'm just discovering this thread, kinda late, but I think I read through all the details.

I checked my paperwork, and my MT P-860-4 governor was manufactured in 2008 (thankfully outside the affected time period), and has been in service since September 2009 -- so, 7 years. It has 400 hrs on it.

From this thread, I just learned that there is a 72-month service interval in addition to the 2000 hr service interval. That surprised me. Can someone speculate or explain why there would be a 6-year service limit on a prop governor? I would think that calendar age would have no bearing at all on the service life, except perhaps for age-hardening of elastomeric seals.

If this service interval should be respected, I am a year overdue, and from what I have learned in this thread, it costs $800. It would seem a sensible choice to consider just buying a PCU-5000X instead.
Another alternative would be to ignore the calendar-based service interval and just operating the MT P-860-4.

I would love to hear supporting arguments for why a 6-yr service interval should be respected on a prop governor.

Thanks
 
I'm just discovering this thread, kinda late, but I think I read through all the details.

I checked my paperwork, and my MT P-860-4 governor was manufactured in 2008 (thankfully outside the affected time period), and has been in service since September 2009 -- so, 7 years. It has 400 hrs on it.

From this thread, I just learned that there is a 72-month service interval in addition to the 2000 hr service interval. That surprised me. Can someone speculate or explain why there would be a 6-year service limit on a prop governor? I would think that calendar age would have no bearing at all on the service life, except perhaps for age-hardening of elastomeric seals.

If this service interval should be respected, I am a year overdue, and from what I have learned in this thread, it costs $800. It would seem a sensible choice to consider just buying a PCU-5000X instead.
Another alternative would be to ignore the calendar-based service interval and just operating the MT P-860-4.

I would love to hear supporting arguments for why a 6-yr service interval should be respected on a prop governor.

Thanks
Steve,
I am in exact same boat as you are with the age/model of the governor and only slightly more hours, at 560 now. I have asked MT via e-mail this question and for a quote but if there is convincing evidence for this overhaul at 6 year interval, I will certainly go with Harzel governor which does not have this calendar base overhaul requirement. With only $400 or so more, I will put a brand new instead of an overhauled one.
 
Based on some of the information posted by those who have spoken to MT directly there is a specific date range. Can we assume the new units being shipped by Vans today are OK.
 
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