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Fired up the plane yesterday to shoot some approaches and test the rebuilt brittian autopilot.  It hasnt flown in about 2 weeks.  Noticed the battery was a pretty low at 11ish volts. but it started no problem.

On runup I noticed the amp gauge was showing a slight discharge.  I even said to my instructor, the amps arent amping but these gauges all suck anyway.  So off we went.  About 800agl the coms started flashing and the transponder went out completely.  Nav/Coms  were blinking and showing weird stuff on the panel.  Reset avionics master and tried emergency avionics switch no help.  Tried radioing the tower but they only got the beginning of one transmission and then nothing else.  I put the gear back down and turned for the downwind (instead of the right turn to 340 they were expecting.)  I could hear them talking in and out.  Finally tower says if you can hear rock your wings.  OK we see that.  If you want to land rock your wings.  OK clear to land 20L.  And we made an uneventful landing and taxied back to the hangar.

Went out last night and started poking around and hooked up the battery tender.  There is a fusible link on the "Power" connection of the voltage regulator.  Fuse was blown.

went to day and got some new fuses.  Battery was up at 12.4 from the battery tender.  Pulled it out and fired it up and the amp gauge showed charging.  In fact showing more charging then usual.  Also the engine fired much faster than normal.  

I'm thinking that fuse was dying for a while and that's why I always felt my battery voltage was a little low and it was draggy turning over.

So im thinking the fuse blew and the battery got low enough (I remember seeing 10.7 on the cig lighter volt meter) that the NAV/COM and xponder just went whacky.

So lesson is

1.  damn I love magnetos

2.  Just because some of your gauges suck doesnt mean all of them do.

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1) Nicely done.

2) Glad you gave a detailed Pirep.

3) fuses and other simple electrical devices like the shunt can fail miserably.

4) +1 for self propelled mags.

5) Electrical ignition has a couple of things to match, coming soon...

6) keep an eye out for what caused the fuse failure.  In the event the fuse killer is still lurking... :)

Pp thoughts only...

Best regards,

-a- 

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On 4/11/2017 at 3:56 PM, TheTurtle said:

  There is a fusible link on the "Power" connection of the voltage regulator.  Fuse was blown.

There are fusible links and there are fuses.  Two different things.  You would have to replace the whole fuseable link if it went.   Fuseable links are higher amperage... 

Something is wrong if you blew the fuse to the voltage regulator...   Sometimes mechanical regulators don't suck because they don't need power... only three wires.   It is a lost artform to adjust them.

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well it wasnt just a fuse issue.

Blew another today.  Fortunately had enough battery and was closely watching the amp gauge on takeoff.  Blew about 2 minutes into flight. so I notified the tower and turned around to land.

My IA thinks the alternator is bad. Has 2000 hours on it. We tested resistance between F1 and F2.  (was gibberish to me, need to reseach how an alternator works he says) We also disconnected F1 and F2 and turned on the master.  It didnt blow the fuse so he says the VR is probably not the problem or at least not shorted. 

Yes it is a fuse not a fusible link.  5amp fuse which is what the R15V0N zeftronics manual calls for.

The manual says you shouldnt have more than .2V difference between the I (power) lead and the battery voltage.  Battery was 11.88.  I lead was 11.66  yes I know thats .22...  So I traced the wire.  It leads directly to the master switch. through 9000 zip ties. Cleaned the connections up but got tired after IA said the bottom cowl, oil cooler, ram air and landing light have to come off to remove the alternator. 

I dont need this crap this week.  Got my IR check ride on friday and was supposed to be cranking out approaches and holds all weekend so I havent rechecked the voltage at the I lead.

Any great ideas?

Im going to search MS for "how to remove your alternator" and hope and pray Spruce in corona has an alternator in stock I can pickup first thing in the am.  Thinking about picking up a VR as well just in case.

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Did you set eyes on the regulator?  You may see it through the oil door.  The 5 amp fuse likely feeds the field circuit.  Basically, it provides line voltage to the regulator, which then outputs a regulated voltage to the field of the alternator.  If the 5 amp fuse is blowing, then I would first concentrate my attention at the regulator, which is easier to work.  Try to determine which side of the regulator the short is on.....or it could be the regulator or the alternator.  There are a bunch of chafe points for the wires on the firewall side, especially routing from the regulator to the alternator and it is fairly easy to trace.

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No the bottom cowl does not have to come off.  While mine was leaned forward against the prop. Pretty sure I could get the alternator off without taking all that stuff off. and yetti paws are pretty big.

If the power to the regulator is blowing a fuse be worried about the regulator.  Call Zeftronics or read the manual and see why fuse blow.

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7 hours ago, takair said:

Did you set eyes on the regulator?  You may see it through the oil door.  The 5 amp fuse likely feeds the field circuit.  Basically, it provides line voltage to the regulator, which then outputs a regulated voltage to the field of the alternator.  If the 5 amp fuse is blowing, then I would first concentrate my attention at the regulator, which is easier to work.  Try to determine which side of the regulator the short is on.....or it could be the regulator or the alternator.  There are a bunch of chafe points for the wires on the firewall side, especially routing from the regulator to the alternator and it is fairly easy to trace.

i replaced the regulator in december.  I checked the wires from it back to the master and to the alternator.  no frays.

6 hours ago, Yetti said:

No the bottom cowl does not have to come off.  While mine was leaned forward against the prop. Pretty sure I could get the alternator off without taking all that stuff off. and yetti paws are pretty big.

If the power to the regulator is blowing a fuse be worried about the regulator.  Call Zeftronics or read the manual and see why fuse blow.

I called them but no call back yet.  i suppose they dont work weekends.  glad to hear the cowl downt have to come off.

 

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To skip taking the lower cowl off...

What probably gets in your way is the air intake tube of the front cylinder.

This came from M20C experience.  The generator is overall larger than an alternator. M20E intake tubes may be different than a C...

Make sure your mechanic has his best tools. Snapping small bolts will not make things go any faster. Expect to use a new silicone seal putting things back...

small steady steps in the right direction will cover a lot of ground.

This is old PP memories being exchanged, not fresh memories...

Best regards,

-a-

Edited by carusoam
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18 hours ago, TheTurtle said:

well it wasnt just a fuse issue.

Blew another today.  Fortunately had enough battery and was closely watching the amp gauge on takeoff.  Blew about 2 minutes into flight. so I notified the tower and turned around to land.

My IA thinks the alternator is bad. Has 2000 hours on it. We tested resistance between F1 and F2.  (was gibberish to me, need to reseach how an alternator works he says) We also disconnected F1 and F2 and turned on the master.  It didnt blow the fuse so he says the VR is probably not the problem or at least not shorted. 

Yes it is a fuse not a fusible link.  5amp fuse which is what the R15V0N zeftronics manual calls for.

The manual says you shouldnt have more than .2V difference between the I (power) lead and the battery voltage.  Battery was 11.88.  I lead was 11.66  yes I know thats .22...  So I traced the wire.  It leads directly to the master switch. through 9000 zip ties. Cleaned the connections up but got tired after IA said the bottom cowl, oil cooler, ram air and landing light have to come off to remove the alternator. 

I dont need this crap this week.  Got my IR check ride on friday and was supposed to be cranking out approaches and holds all weekend so I havent rechecked the voltage at the I lead.

Any great ideas?

Im going to search MS for "how to remove your alternator" and hope and pray Spruce in corona has an alternator in stock I can pickup first thing in the am.  Thinking about picking up a VR as well just in case.

If your alternator really has 2000 hours on it I'd suspect the brushes are worn down to the springs and shorting out the field circuit.

If you have a Prestolite alternator, the brushes can easily be removed without removing the alternator from the plane.  Simply remove the side cowl, disconnect the wires from F1 and F2, then remove the two screws which hold the brush holder into the back of the alternator.  Brushes and brush holders are easy to replace.  While the holder is removed take a piece of fine Scothbrite and polish the alternator slip rings through the brush opening by turning the propeller by hand.

Clarence

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3 hours ago, M20Doc said:

If your alternator really has 2000 hours on it I'd suspect the brushes are worn down to the springs and shorting out the field circuit.

If you have a Prestolite alternator, the brushes can easily be removed without removing the alternator from the plane.  Simply remove the side cowl, disconnect the wires from F1 and F2, then remove the two screws which hold the brush holder into the back of the alternator.  Brushes and brush holders are easy to replace.  While the holder is removed take a piece of fine Scothbrite and polish the alternator slip rings through the brush opening by turning the propeller by hand.

Clarence

Well that probably would have saved some time...

7 hours ago, carusoam said:

To skip taking the lower cowl off...

What probably gets in your way is the air intake tube of the front cylinder.

This came from M20C experience.  The generator is overall larger than an alternator. M20E intake tubes may be different than a C...

Make sure your mechanic has his best tools. Snapping small bolts will not make things go any faster. Expect to use a new silicone seal putting things back...

small steady steps in the right direction will cover a lot of ground.

This is old PP memories being exchanged, not fresh memories...

Best regards,

-a-

Turned out to be a pretty good day.  I dropped the cowl but only unhooked the ram air.  Didnt have to move the light or oil cooler.  Was able to move it down enough to get to the alternator bolts and get it out.

Went down to spruce around noon.  Got started on the plane around 2 and finished installing the alternator by 8 and getting the cowl buttoned back up.  Going to go back tonight and rerun all the new wires as well as the new push to test light in the panel from the voltage regulator warning lead.  I figure a couple hours on that so 8 hours R&R with no experience doing it isnt bad.  IA will come take another look tomorrow.  Probably not going to like my safety wire job.

Only issue is the pully outer diameter was wider so getting through the hole took some tin snips and one of the stupid cotter pins in the alternator bolt took me a solid hour to get out.

Now if it actually fixes my issue Ill be really happy.

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One's 'Antenna goes up' when you say that something changed...

When a pulley changed diameter or width it says check the details.  Something might not be right...

i had this happen in the automotive world and ended up stuck for a bit when the belt broke.  I was supposed to re-use the old pulley, not the new pulley.  Stopping every mile manually operating the water pump didn't work very well... got me to the mechanic though... :)

1) this is not the automotive world.

2) i am only a PP.

3) maybe I didn't understand what you meant.

4) what changed, when did it change, regarding pulley diameter and width?

This is only an illustration of why it is good to continue to work with your mechanic.

Best regards,

-a-

Edited by carusoam
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18 minutes ago, carusoam said:

One's 'Antenna goes up' when you say that something changed...

When a pulley changed diameter or width it says check the details.  Something might not be right...

i had this happen in the automotive world and ended up stuck for a bit when the belt broke.  I was supposed to re-use the old pulley, not the new pulley.  Stopping every mile manually operating the water pump didn't work very well... got me to the mechanic though... :)

1) this is not the automotive world.

2) i am only a PP.

3) maybe I didn't understand what you meant.

4) what changed, when did it change, regarding pulley diameter and width?

This is only an illustration of why it is good to continue to work with your mechanic.

Best regards,

-a-

belt is same tension as the old one.  The bracket allows adjustment.  IA will check it before I fly.  I was thinking about swapping pulleys but the factory put the orange paint on the pully nut so Im sure if i mess with it and then have warranty issues Ill be screwed for $500.  The depth of the pulley is the same as the old one just wider diameter.  Belt isnt at any angle or side load.

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Point it out to your mechanic.

The paint on the nut is probably there to indicate that it has been torqued tight. If it were to loosen, the paint would break.

I would ask the mechanic if the new pulley or the old pulley is the right one to use. Show him what you are seeing.

Swapping the pulley if needed, less than an hour?

what does the belt look like, V-shaped, scalloped side facing the pulley? (I don't remember)

PP thoughts only.

Best regards,

-a-

Edited by carusoam
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Reaching through the engine from the other side to get the cotter pins... that is with a smaller starter.   Using a light to line things up. Using forceps and needle nose pliers. Being able to work blind and just feel it with fingers.

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Different alternators require different rotation rates.  Different size pulleys are part of that.  When you are changing from one alternator to another, you are going to have to modify the baffling a little bit.  I'd point it out to the IA, but I sincerely doubt there is a problem.

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