Jump to content

231 electrical question


Geoff

Recommended Posts

Hey guys,

I just scrubbed a flight due to a low voltage indication in my 82 12 volt 231. Both the annunciation panel and the JPI 900 were warning low voltage. 

 

The JPI showed 11.7 volts and 0 amps.   This was after a ground run and engine run up. Any thoughts as to what it could be?  

I flew the plane 1.6 hours the previous day which was the first flight since an oil change and all was well. 

Link to comment
Share on other sites

First thing to look at...

The field wire.

This is the wire that the VR sends a signal to the alternator to generate voltage...

If  the wire has become disconnected, no signal is received... no voltage gets supplied...

Common casualty of high temperature and vibration.

If broken, weakened, or accidently grounded, a visual inspection may be a simple way to find the problem... find the VR, find the Alternator, they should be connected together by a few wires... one is marked ‘field’... or it’s stub is connected to the empty spot marked ‘field’... :)

PP thoughts only, not a mechanic...

Best regards,

-a-

Link to comment
Share on other sites

4 minutes ago, Geoff said:

Where is the field wire located and what does it connect to?  I assume off the regulator somewhere?

I was editing as quickly as possible....

See the rest of what I updated above.

Finding the voltage regulator in a K may be more challenging than other Mooneys...

Some may be copilot side, inside firewall...behind the instrument panel...(?)

Best regards,

-a-

Link to comment
Share on other sites

Like Anthony said. My guess is that the alternator is located very close to oil filter. Somebody may have knocked off(or broke) one of the alternator wires. 

The alternator is attached to the back of the engine just behind the oil filter. 

  • Like 1
Link to comment
Share on other sites

The alternator is low on the back of the engine.  My finger is pointing at the field terminal.

You can check for power at the terminal with a volt meter, or turn on the master and alternator switches, then using a few paper clips linked together to form a chain, swing them near the back of the alternator to see if its created a magnetic field.

 

Clarence

P_20190113_140634.jpg

Edited by M20Doc
Link to comment
Share on other sites

Check the drive coupling.  Mine failed last year and after lots of electrical troubleshooting I discovered that the rubber drive coupling was slipping. You can check this by trying to manually turn the alternator through the holes in the cast mounting adapter that goes between the alternator and the engine.  With mine, I could turn the alternator by hand.  $500 later, new coupling and it works like new.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.