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M20C Generator install question

LucasC

By LucasC
in Vintage Mooneys (pre-J models)

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LucasC Enthusiast

LucasC

Posted
Posted

Going to have the generator changed out soon on my M20C.  Was wondering if the prop has to come off or not?  If not mechanic can do it in my hanger if it does have to come off he wants it to go to his shop.  Thanks in advance.

Lucas

moodychief Proficient

moodychief

Posted
Posted

The prop only needs to come off if the belt needs replaced.   If belt is in good condition, you will need to take the lower cowl off for easy access and safety wiring after install.

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jamesm Mentor

jamesm

Posted
Posted

I have taken generator off a number of times you should not  have to remove  the prop. Unless you are planning on replacing the belt  if so  you may consider switching to  an alternator.

You might want to check with the A&P first some are particular on how things come apart and go back together.

 

James '67C

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carusoam Grand Master

carusoam

Posted
Posted

+1 Generator is a kinda easy job... for my old M20C...

Got a low cost OH’d one from AS... 0.2AMU?

Requires lowering the lower cowl and a few other things that get in the way....

Make sure the air cooling hose to the front gets connected... good time to replace the hose too...

My sticks and stones and springs VR melted the lead out of the first generator...

So got a new Zeftronics device for that.

Going with a new alternator is great if the Finance administrator approves the additional funds...

Best regards,

-a-

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47U Mentor

47U

Posted
Posted

Check the three tabs on the mount bracket which the case bolts go through.  The aft tab was broken on my ‘63 C.  Dan at LASAR had a replacement and it was beefed up.  I probably wouldn’t have see the broken tab except I was replacing the prop oil line and the aft bolt had a clamp on it.

Good luck!

Tom

 

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0TreeLemur Grand Master

0TreeLemur

Posted
Posted
On 9/3/2019 at 9:31 PM, LucasC said:

I had the generator swapped out yesterday and man what a difference.  Actually coming online around 800RPMs now.  Was around 1700RPM before it failed totally.

Did you install a refurbed generator or did you convert to an alternator?   The generator on my C doesn't really seem to contribute many electrons until about 1700 rpms too.

-Thx.

Browncbr1 Grand Master

Browncbr1

Posted
Posted

This reminds me,,  I have a serviceable as removed generator on my shelf if anyone needs it.  Free to any cheap bastards out there, as long as I don’t have to ship it.  :)

Shadrach Grand Master

Shadrach

Posted
Posted
7 hours ago, 0TreeLemur said:

Did you install a refurbed generator or did you convert to an alternator?   The generator on my C doesn't really seem to contribute many electrons until about 1700 rpms too.

-Thx.

A good generator with a modern voltage regulator will be online aroung 1100rpm.

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carusoam Grand Master

carusoam

Posted
Posted

Rinj,

See if this makes sense...

Similar to other technology improvements over the years...

They won’t make sense for everyone. :)

But....

If you like to fly IFR, and depart into a low ceiling, and have your battery charging before you depart...

The alternator is a touch better for the job, even though the plane could have a 50year old generator in it.

alternators start to charge slightly above idle rpm. Generators start to charge at about 1700 rpm... the plane will be draining the battery from start-up until you reach enough rpm to charge...

PP thoughts only, my 65C’s Generator got a nice zeftronics voltage regulator to improve things, but it still was connected to a generator...

Best regards,

-a-

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59Moonster Collaborator

59Moonster

Posted
Posted
9 minutes ago, carusoam said:

alternators start to charge slightly above idle rpm. Generators start to charge at about 1700 rpm... the plane will be draining the battery from start-up until you reach enough rpm to charge...

Wasn't aware of that. Thanks. Anybody know if there is an alternator for M20A?

carusoam Grand Master

carusoam

Posted
Posted

Expect plane power has an alternator for the O360...

You will want to check with them if it has been STCd for the M20A...

I can’t think of any reasons it can’t be...

The alternators go in the same space as the generator and are much smaller...

The corresponding VR will occupy the same space as the generator’s sticks and stones and springs VR...

 

Unfortunately, when I looked this up moments ago... I only found this...

https://planepower.aero/aircraft-alternator-support/application-information/?ma=Mooney International Corporation&mo=M20A

 

About the alternator operations.... they do produce power down at low rpms... but, it is pretty low and climbs with rpms until it produces max power... still much better than the generator.  Just a new set of limitations...

At idle, my generator will show a discharge with everything in the panel running... at 1000rpm there is plenty of power to run everything...

Some Logic is required... to not drag the brakes, or speed down the taxiway... but at least you know things are working before departure...

PP thoughts only, not a mechanic...  definitely check with planepower and your mechanic to see how this can be done for your M20A...

See if the other M20A owners have a solution.... :)

Best regards,

-a-

 

Andy95W Grand Master

Andy95W

Posted
Posted
7 hours ago, Rinj said:

Wasn't aware of that. Thanks. Anybody know if there is an alternator for M20A?

 

4 hours ago, chriscalandro said:

If you battery is low, it’s night, and you have a generator, you can either use the landing light or talk on the radio. Not both. 

I don't think I would be so quick to swap out a generator, and I don't really agree with Chris (unless you base your airplane at Teterboro).

Yes, you may have to turn off some unused avionics, and you definitely want to get an LED landing light.  Maybe consider LED navigation lights if you fly a lot at night at big controlled airports.  But those old generators are hell-for-stout and really just need brushes every once in a while. Also stone-ass simple and the way the airplane was designed.  

I know of a Mooney owner with generator who just flew to Oshkosh.  He was a little concerned about long taxi times waiting to park/waiting to take off and not generating any appreciable electricity.  Bottom line- it was not a problem.  He had been thinking about an alternator conversion but no longer is.

PlanePower makes an alternator conversion for the M20A for $859, but it's not an easy conversion, particularly in regards to baffling.  And after Hartzell acquired them, quality has gone down and customer complaints up.  I'd keep your generator (unless you're based out of Teterboro, like I said.)

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