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M20C alternator conversion


Htwjr

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I just got the shop labor bill for converting my '67 M20C to an alternator and it seems high to me.  The shop charged 17.5 hours labor for a total of $1225 labor.  Adding in the cost of the alternator it puts the total at 2G.  I am curious as to what it has cost others in time and money to convert their planes to an alternator.  Thanks

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Holy cow! I did mine back in like 2009 and it took me about 4-8hrs to complete the change with my mechanic. 17 sounds extremely over excessive. If I was you call a shop like LASAR and ask them how much time they charge people for that. Then go back to your shop and ask what the heck! Rebuttal it before you pay it otherwise you wont get the money back.

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Not sure about the bill, but I can tell you the work envolved takes about that long. Removing the lower cowl alone takes a few hours, on is even worse, reworking all the baffling can be an issue. Getting behind the fire wall to access the wiring and mounting for the Voltage regular can be a pita depending on windscreen, access panels, and instrument panel, wiring up the low voltage light, simple paperwork, filing a 337, removing the prop etc... I plan on at least a few hours for that on an off, then another hour to saftey wire the darn thing. Then removing the old generator, battling with the bendable clips that provide the safty for the bolts to the bracket altenator on, sealing up everything with silicone. Then fixing the little things like the crappy wires that connected to the gen, or a bad terminal that was ready to break anyway. I probably had a half days work running back and forth to O'rileys to find a belt that would fit because the one listed in the installation manual didn't fit the old flywheel we have. Sounds fair to me... Not as simple as the STC says...

FYI- Plane Power's support is stellar!! Ask for Jason Hutchinson.

Cheers,

Matt

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Price of the alternator (~750) seems fair - a shop would chart list price rather than the discount you can get from your favorite retailor.

 

17.5 hours MAY seem excessive at first

 

But if indeed what looks like a simple replacement  involves removing and reinstalling the prop, and reworking the cowling, etc ... you may get quickly to that.

 

The paper work (W&B and 337) and miscelaneous nuts/bolts should be about an hour.

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Some people answered outright that it was too high w/o indicating if they were talking about the same model. When I did such conversion in a Cessna 140 I used to own it took 8 hrs or less. Obviously not the same airplane. Two days of work including paperwork (w&b, etc) if it is on the high side it is not by much.

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I did the Plane & Power alternator conversion in 2009, and did the Skytec starter at the same time, and here are the details from the invoice.

  1. Uninstall generator and starter     3.5hrs  
  2. Install alternator and starter          3.0hrs
  3. Panel wiring, light, breaker, logs   6.0hrs

So a total of 12.5hrs @ $68/hr = $850,  for labor for both the alternator and the starter.

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Which conversion alternator conversation did you do? Plane Power? or ??

I went the expensive route before Plane Power had came out conversion kit.  If someone wasn't familiar  Mooney's  they could soak you. Like someone  mention earlier that lower cowl can be a stinker at times. Even when I had  the generator that I had to take out every so often to flash field on the generator on my '67 M20C  (Didn't feel comfortable doing on the airplane plus more through of inspecting the generator but wasn't  the easiest way) if everything went well I could do this about  ~ 4 to 6 hours to remove and install the generator didn't include the time taking it to the generator shop. 

However since I went the expensive route  (before Plane Power had a kit)  I had prop off for the conversion to the B hub AD, I changed out the starter ring gear assembly to one that was for the Alternator (narrow belt)  and did the alternator conversion at that time.

Off my memory

Starter gear ring assembly ~ $250 -$300

Voltage Regulator  ~ $200 - 220

Plane Power Alternator ~$450 - $550

new belt  ~$34 ( I am not sure but I believe the Plane Power conversion kit accepts the wider generator belt and may use different diameter size pulley) if that is case would save a lot of time if they didn't have to pull the prop.

5A Field breaker ~$20

Then I did  a bunch other stuff like replace all the  wire for the  field circuit  that goes to the master switch, installed LC filter like later year Mooney's with Alternators.(probably wasn't necessary  with plane power alternator)  I wasn't in hurry  doing this project and spent a fair amount of time  researching on how to do this  prior to Plane Power PMA/STC  coming out with an Alternator for Prestolite replacement.

I definitely didn't go the cheap route but learn a lot in the process.

James '67M20C 

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Yes, I did the plane power conversion. My generator was working fine but the bolt hole on the back of the generator housing broke allowing the generator to twist and the pulley rub on the lower cowl closure. I took the generator off myself and tried briefly to get a back housing. A few people including the mechanic recommended converting to alternator. I flew the plane to his shop with the generator already off. If I had any idea it would cost that much I would have looked harder for a generator housing especially since the generator was working fine. If anybody needs a generator that only needs a back housing let me know.

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I had my  generator rubbing on the cowl enclosure too.  but I believe it was  when  the cowl enclosure  was installed  the engine mounts rubber doughnuts  needed to be replaced  prior to installation of the cowl enclosure.  With the generator already off that should have been  at least 4 hours of labor off your bill, one would think.

Sorry to hear.

James '67 M20C

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