[scsmith]

Well, my MT governor has 83 months in service, with a 72-month calendar limit overhaul requirement. West coast estimate for overhaul is $1050, so instead, I bought a Hartzell governor from Vans.

I tried to install it today. It is almost plug-and-play, but not quite. Ultimately, the only real change needed is longer studs on the governor mounting adapter. If you have long studs already (31c-16) then you should be ready to go.
I said "ultimately" because for a while, it looked like the installation would be more difficult. The six screws that hold the governor head to the body are clocked about 30 degrees with respect to the MT governor. This matters because the bracket for the control cable attaches with three of these six screws, and with it sticking in a different direction by 30 degrees, the control cable routing and length and bend radius is severely changed. Add to this that the Hartzell governor is 3/4" longer, so it requires more bend in the control cable to curve around from the firewall penetration to the bracket for anchoring the control cable.

After a lot of head scratching and fiddling, I resigned myself that I would need to make a different bracket or something, but I thought I would play with clocking the control arm to see if I could get enough clearance to put the cable rod-end on the forward face of the control arm. So I moved the fine adjustment of the governor head to the ends of the slots and "Eureka", there are six additional screw holes, in the same orientation as the MT governor screw holes. So, I changed over to that set of six, mounted the bracket as it was on the MT, and all is well. You can not see this set of holes until you move the governor head to the limit of travel in the slots with the screws in the first set of six holes.

Note that when I originally built the airplane, I modified my bracket from Vans to have the control cable rod end attach on the rear face of the control arm, a much cleaner arrangement. I am delighted to be able to retain that arrangement. You can see that here:

http://www.hpaircraft.net/rv8/governorbracket.pdf


The one drawback to this plan is that the Hartzell governor reportedly requires about 1700 rpm to cycle the prop to coarse pitch, whereas the MT governor would cycle the pitch to coarse even at idle, well at least at about 900 RPM. I tested it. This was a nice safety feature in the hope that a windmilling engine will make enough oil pressure to get the prop to coarse pitch to improve gliding range.

Oh well. The Hartzell governor does not have any calendar limit for service, only a TBO of 2400 hrs or when the engine is overhauled.

 

[Bavafa]

Thanks for the post and sharing your lesson-learned. I have been contemplating the same thing, only hate losing the option that you can change the prop to full coarse at idle which is part of my emergency task list. At nearly a $1000 for overhaul, I wonder if it is better to buy a new one but then again, what is inside of them that has a calendar time limit for overhaul?

 

[Larco]

By Steve Smith: Note that when I originally built the airplane, I modified my bracket from Vans to have the control cable rod end attach on the rear face of the control arm, a much cleaner arrangement. I am delighted to be able to retain that arrangement. You can see that here:

I also modified the bracket as you did when changing over to the Hartzell. Good idea and works great. I couldn?t make it work smooth the other way.

If Vans is going to sell the Hartzell Gov in large enough numbers it would be nice if they made a proper bracket available? Larry

 

[A5555]

good topic, anyone have any pictures of the install?

 

[scsmith]

good topic, anyone have any pictures of the install?

The pdf file I linked to is probably more useful than an installation photo with poor light and a bunch of other stuff in the way.

 

[A5555]

The pdf file I linked to is probably more useful than an installation photo with poor light and a bunch of other stuff in the way.

how close is it to the firewall?

 

[JonJay]

Thanks for the post and sharing your lesson-learned. I have been contemplating the same thing, only hate losing the option that you can change the prop to full coarse at idle which is part of my emergency task list. At nearly a $1000 for overhaul, I wonder if it is better to buy a new one but then again, what is inside of them that has a calendar time limit for overhaul?

An "overhaul" includes complete magna-flux of all the metal parts. That is what gets expensive. I am not sure where the time limit came from. Many of the MT governors where made by Jihostroj. MT simply stuck a label over the top of the Jihostroj data plate. You can czech (ha ha) yours, but the Jiholstroj has the same time limit. I am not sure why.

The prop shop I used said they could do an "inspection and reseal" vs a complete overhaul for about $300. They felt that this would be adequate for the time in service vs a complete overhaul, but that is just one shop speaking.

 

[Bavafa]

An "overhaul" includes complete magna-flux of all the metal parts. That is what gets expensive. I am not sure where the time limit came from. Many of the MT governors where made by Jihostroj. MT simply stuck a label over the top of the Jihostroj data plate. You can czech (ha ha) yours, but the Jiholstroj has the same time limit. I am not sure why.

The prop shop I used said they could do an "inspection and reseal" vs a complete overhaul for about $300. They felt that this would be adequate for the time in service vs a complete overhaul, but that is just one shop speaking.

Jon,
Regarding the Jihostroj, please see the link below in their FAQ. it indicates that there is no calendar time limit for TBO but also it is not clear if all MT Gov. are made by Jihostroj. It does say that MT was a distributer but also it indicates that MT is now has their own governor.

http://www.propellergovernor.com/faq/

 

[JonJay]

Jon,
Regarding the Jihostroj, please see the link below in their FAQ. it indicates that there is no calendar time limit for TBO but also it is not clear if all MT Gov. are made by Jihostroj. It does say that MT was a distributer but also it indicates that MT is now has their own governor.

http://www.propellergovernor.com/faq/

I swear I looked at this exact link a couple months ago when I discovered by MT was Jihostroj and it said 7 year calendar time (not 6 like my MT manual states). Maybe I am just plain crazy and losing it but I distinctly remember noticing it was 7 instead of 6.
So, for those with MT governors, it is really easy to tell if they are a relabeled Jihostroj by peeling back the sticker and seeing if there is an original Jihostroj data plate. If so, no calendar limit is a good thing!

 

[scsmith]

how close is it to the firewall?

I will measure it tomorrow when I head out there, but I think the Hartzell still has about 1-1/2 to 2" clearance to the firewall.

sorry for the typo in the OP, the Hartzell is 3/4" longer, not 3.4" longer as I had originally typed.

I am kicking myself about one thing right now -- I should have pulled one of my studs out and measured it to be sure that the new ones I just bought will be longer. The parts manual calls for 31c-16 studs, and there is a note in the Hartzell installation instructions that says that stud length is long enough. But if I already have 31c-16 and it turns out I need longer ones, I'm going to be mad at myself.

On that topic, is there any magic to getting the old studs out? My normal procedure would be to put two nuts on the stud, jammed against each other, and turn the stud with the inner nut. Any reason why that shouldn't work? Any other tricks?

 

[JonJay]

On that topic, is there any magic to getting the old studs out? My normal procedure would be to put two nuts on the stud, jammed against each other, and turn the stud with the inner nut. Any reason why that shouldn't work? Any other tricks?

Just put the nuts as far down as you can so you put as little side load on the stud as possible. They should come right out. If they don't, stop, and start treating with penetrant.
Also, be sure you don't have any oil leaks between the drive adaptor and acc. case. Now is the time to fix it if you do. This is a very common place for a leak. You will need a 1/2" crows foot and some patience.

 

[scsmith]

Just put the nuts as far down as you can so you put as little side load on the stud as possible. They should come right out. If they don't, stop, and start treating with penetrant.
Also, be sure you don't have any oil leaks between the drive adaptor and acc. case. Now is the time to fix it if you do. This is a very common place for a leak. You will need a 1/2" crows foot and some patience.

Thanks, I'll tackle this tomorrow. Why a crows foot? I was thinking of using a deep socket, but now I think about it, it depends on the luck of having the two nuts line up flat to flat well enough to get a socket over them. I've had fairly good luck with that in the past, but I suppose the crows foot is a sure bet, and puts torque only on the 'inner' nut.

 

[JonJay]

Thanks, I'll tackle this tomorrow. Why a crows foot? I was thinking of using a deep socket, but now I think about it, it depends on the luck of having the two nuts line up flat to flat well enough to get a socket over them. I've had fairly good luck with that in the past, but I suppose the crows foot is a sure bet, and puts torque only on the 'inner' nut.

Sorry. Crows foot on the adapter nuts IF you need to replace that gasket.

 

[JonJay]

An "overhaul" includes complete magna-flux of all the metal parts. That is what gets expensive. I am not sure where the time limit came from. Many of the MT governors where made by Jihostroj. MT simply stuck a label over the top of the Jihostroj data plate. You can czech (ha ha) yours, but the Jiholstroj has the same time limit. I am not sure why.

The prop shop I used said they could do an "inspection and reseal" vs a complete overhaul for about $300. They felt that this would be adequate for the time in service vs a complete overhaul, but that is just one shop speaking.

UPDATE - No. The same shop that loosely quoted me "$300" just told another VAF'r an inspection and reseal would be $800. Go figure.

 

[scsmith]

epilogue

I thought I would finish up the lessons learned here with an epilogue.

First, there was a request for a picture of the control cable installation on the modified VA-153 bracket.

So here is that:

You are looking down along the firewall, at a 45 degree angle to the left. Up in the picture is forward on the airplane. Sorry its so dark - it looked good on my iPhone.

There was a question about how close the governor comes to the firewall. With my installation with the control cable rod-end attached on the aft side of the control horn, the head of the bolt is the closest thing to the firewall. It is 1.5 inches away at fine pitch, and about 1.25 inches at coarse pitch. The governor shaft extends aft as it is actuated.

Finally, To answer my own question from the other thread, the odd drive gear that is supplied by Hartzell, which is missing teeth, works because the governor adaptor has a complete female gear socket, so the teeth are fully meshed all the time.