Amp Meter Flutters

[Abe]

Well, it's been awhile since I started looking for the culpit causing the fluttering amp. On one of the snowy days here recentely, I started looking at what kinda work was going to be envolved in installing new wing tip strobes....I had the right wing tip off and was measuring things and found a ground wire from my nav light was disconnected....(I don't know how I missed this when I first started looking way back when) The ground was reconnected with a new screw and connector...

Well, today it was nice so I took 04D to Hell's Canyon to meet some of my buddies and guess what....the Amp Meter was as steady as the rock of gilbrator.... But again thanks for all the advice from you folks on this fine forum....That damn thing has been nagging at me for most of a year...

Heading for the Seven Devils in Idaho and greener pastures in Hell's Canyon

And guess what I found on the way...The amp meter was steady as a rock....

My Buddies at Temperance Creek came to greet me...

Now back home to the Ice Box...until next time...

[ronjenx]

My brother's '50 170A had similar symptoms. We went to the regulator first. I cleaned the points and it brought about a change in symptoms, but didn't fix it. So, I took the regulator off. I drew paper through the points and washed them with contact cleaner. The regulator base needed cleaning where it touches the firewall. We cleaned the firewall around the regulator mount holes, too. Put it all back together and has been fine since.

[GAHorn]

All voltage regulators MUST have their bases GROUNDED to the airframe.

Although the regulator may mount with shock-absorbing rubber grommets, there MUST be a grounding strap for the regulator to properly work.

[canav8]

Folks I am sadden by all that have replied to this individual that flys his aircraft with this problem. Not one of you made a recommendation:To not fly this aircraft till it was resolved. Electrical problems have no business being in the air. I lost a good friend to an electrical fire in his Hyperbype homebuilt. This aircraft was 5 years old and had over 400 hours on it. It is tube and fabric which probably didnt help with the fire. He disregarded his ammeter as being errant. Although I was not part of his Maintenance practice, he made mention of it to me and he flew it anyway. Sad thing was, he burned up trying to get it back to the airport. Electrical indications can sometimes mean a faulty guage but as my old friend found out, it should have spent time on the ground. I shutter on the guys that comment that you have been flying your aircraft around for a year without fixing it.Sorry for my opinion but loss of life could have been prevented.

[ronjenx]

All voltage regulators MUST have their bases GROUNDED to the airframe.

Although the regulator may mount with shock-absorbing rubber grommets, there MUST be a grounding strap for the regulator to properly work.

The base on the regulator I worked on has a strap built into it which is connected between the base and the metal insert in the rubber grommet. the metal insert makes contact with the firewall.

[GAHorn]

Folks I am sadden by all that have replied to this individual that flys his aircraft with this problem. Not one of you made a recommendation:To not fly this aircraft till it was resolved. ....

I don't think anyone's troubleshooting advice here could be construed as encouragement to perform the tests while flying or otherwise operating unsafely, .... but your comments are certainly worth considering. There are very few malfunctions which can be taken airborne and easily defended should anything go wrong. (As a friend once told me, whenever something like this happens I always use the following logic: "Let's start at the trial... and work our way back to the accident..." ... and think about how it will sound.)

[Abe]

Folks I am sadden by all that have replied to this individual that flys his aircraft with this problem. Not one of you made a recommendation:To not fly this aircraft till it was resolved.

Canav8, I appreciate your thoughts on this matter and I'm saddened by your friend's death, but noone but me knew the totality of the circumstances surrounding this problem that I put out on this forum to elicited assistance and advise. I put allot of effort (as did our local IA) into locating the culprit causing this fluttering amp meter before my next flight, but to no avail....it nagged at me every time I watched it...and there was no rhyme nor reason as to when it would do it's thing...and that little nag in the back of my brain told me it was just what I found...a loose ground wire...again being the only one that seen what was going on on each flight....Would I do it again....Damn right I would....why hell, I feel safer flying 04D with the fluttering amp into Hell's Canyon than I do driving my PU to town...And I do sure appreciate this forum and all of its experience that everyone is willing to share with us....

[Abe]

Well the saga continued...not only did the amp meter keep fluttering, but the alternator was not charging the battery now...All this renewed itself about 6-months after my above post...It would charge at low RPMs and discharge during cruise flight...well finally after tinkering and having to prop start 04D several times in some interesting locals and a new battery we come to the conclusion it had to be the new alternator and/or regulator that had been put on when 04D had it's engine overhauled some 2+-years ago...

Sent them both (alternator & regulator) back to the factory...they tested good... put things back together and tried her again...She worked fine...charged properly and everything...So my point here is...even though I can't say for sure, but it had to have been that during the reconnecting the voltage regulator back up to the airframe, we got the proper ground that George was talking about earlier on...Now the amp meter is again as steady as a rock (I hate to say that again as it may jinks me) and I haven't had to prop start 04D since...I hope this is again the end of this story...and if any of you experience similar symptoms you'll be able to fix it a bit quicker...

[CAVU Mark]

Well Abe has perfectly described what is going on with my 170A, original generator and probably a replaced regulator. Generator was rebuilt last May, regulator history is unknown. Today I checked and cleaned the VR grounds, ohm meter says 0.3 ohms or so. Tried cleaning the points and saw the twitch diminish, swing wide and wildly, stop charging altogether and then back to the twitch. Reposistioned the plane and the twitch was lessened.

All this happens without a load on the plane, and occurs even more so with a load. Twitch can be from a few 3-4 amps to almost stop to stop on a 30Amp meter, center zero. Sounds like I need to chase some ground issues in the entire airframe.

Any troubleshooting tips or should I just increase my insurance?

Mark

[Abe]

Mark,
I feel your pain, heck I still have scars on my belly from crawling around in 04D chasing wires. Looking back on my experience I think that remounting the voltage regulator (taking if off and putting it back on the firewall) may have been part of the success to the end of our story as today she still is as steady as a rock. I wasn't there when the IA did the removal, so I can't say what he actually did. The upside to that ordeal was I learned allot about 04D from the inside out. Gotta love these nearly 60-year old flying machines. I was talking to Wup last night about their bush wheels and if I ever put them on 04D, it would be to save the airframe and avionics. You gotta land at Lord Flat on a set of 8.00x6 and a set of 29" or 31" bushwheels to appreciate what I'm saying. If you don't mind loosing a few mph, the up front cost would be cheap insurance for what you'd pay in time and money (and scars) in 1-3 years of off airport landings.

[GAHorn]

Well Abe has perfectly described what is going on with my 170A, original generator and probably a replaced regulator. Generator was rebuilt last May, regulator history is unknown. Today I checked and cleaned the VR grounds, ohm meter says 0.3 ohms or so. Tried cleaning the points and saw the twitch diminish, swing wide and wildly, stop charging altogether and then back to the twitch. Reposistioned the plane and the twitch was lessened.

All this happens without a load on the plane, and occurs even more so with a load. Twitch can be from a few 3-4 amps to almost stop to stop on a 30Amp meter, center zero. Sounds like I need to chase some ground issues in the entire airframe.

Any troubleshooting tips or should I just increase my insurance?

Mark

Mark,
First, use a small jumper-wire and connect your generator small terminal (Field) directly to Ground...and see if you have a steady charge. If so...the fault lies either with your regulator (...or your gen-fld-terminal-to-regulator connection thru your master switch.)
If connecting your gen fld terminal to ground does not provide a charge, the fault is likely within your generator or your generator has lost it's polarity.
To re-establish generator and regulator polarity: With engine NOT running but with Master Sw ON... MOMENTARILY jump your regulator ARMature terminal to it's BATtery terminal. (This causes a short spark...and establishes a residual-magnetism within the generator and regulator). Now with no jumpers at all, start your engine and run it up to 1500 rpm or higher and see if your gen/reg now produce a charge. If YES...then it was lost polarity.
If no...then try the gen Field Terminal to ground again and get back to us.

REmember: Your cockpit master switch provides TWO circuits. One: it actuates the battery-solenoid by giving it's small terminal a Ground. Two: It connects the gen Field terminal to the regulator Field Terminal. (The regulator controls the generator by controlling the generator's field-terminal connections to ground. This is why the regulator MUST have it's base connected to GROUND.)

[CAVU Mark]

Thanks for the help. Today I measured the voltage out of the generator and it is steady at 12.8 or so with varying loads. Not sure that tells you anything but it was another data point. They measured resistance from regulator to ground is very low... 0.3 ohm. I also think the master switch is original which may be the problem. Today the twitch is only 2-4 amps and a mostly positive charge when the RPMS are over 1000. With the landing light on I need to go to 1200 for a positive charge.

Mark