Should I expect this problemn to be fixed

[cgzro]

A little knowledge is a dangerous thing

I completely disagree. Pilots should know as much about their aircraft as possible.
You may not be able to fix it but you should know how the fuel system , electrical , controls and hyraulics systems work. Things can and do go wrong in flight and you better know how serious it is and what your options are. To suggest otherwise is dangerous.

[Beefitarian]

You used to be able to go to several places to get "rebuild kits" for the starter motor in your car. Now it's even difficult for many mechanics to get those parts. Often they have to get a "factory rebuilt" unit and swap the worn one out because brushes and bushings are not available. Other parts are sealed electronics that can't be opened without destroying the part.

It's difficult to fix many things now and that drives the habit of replacing instead of repairing them.

Second we live in a world where people can't change a tire or fan belt, never mind adjust the dwell on a set of points.

[Colonel Sanders]

After a quarter-hour of struggling, managed to
determine that the oil level in my daily driver
was a quart low.

After another 45 minutes, couldn't figure out
where to put the oil in. Called a tow-truck
driver. After another 1.5 hrs he showed up
and taught me about the mysterious "710"
cap which is where the oil goes in:

[Beefitarian]

Probably more than half the population wouldn't know the oil was low until the mechanic that fixed the engine, after the tow truck took the vehicle to him because it stopped running, told them, "It was out of oil and I had to replace two main bearings."

[Shiny Side Up]

A different generation, I suppose. We weren't all
Starbucks babies with manicures that called in the
trades when we had a flat tire or a dead battery

One of the unfortunate things in life is that less and less people these days grow up with a rural background which is conducive to learning such skills. We also live in a considerably easier time, and a more "throw away" society. People don't fix things anymore they get new ones. Its increasingly harder to do that too though, especially if you see under the hood of any newer vehicles. One often takes for granted the advantage one has with a life of learning said skills, that unfortunately isn't afforded to everyone. I have plenty of urban dwelling friends that don't have driver's licenses, and have very little knowledge of how motor vehicles work. Lots of people don't appreciate the dangers of working with hydraulic machinery, which is often one of the things that dismays me.

Here's one out there for some of you. Do you remember the farm safety coloring book that used to get issued every year? Everyone I know who was raised in the praries has seen it from Alberta to Manitoba. Looking back it was exceedingly graphic for something you gave to five year olds. There was the picture of the guy suffocating in grain, the guy pinned under a round bale and of course the kid wrapped up in the PTO. The world used to be considerably less bubble wrapped.

[GyvAir]

I talked to a great mechanic yesterday who helped me with the problemn. And again I'd like to thank you all.

@eddyb123 What did the problem turn out to be?

One thing missing in this discussion is the other two sides of the story; the mechanic's and the truth.
It's not unreasonable at all to think that a 50 year old aircraft might have more than one problem at a time. 50 year old starter cables (if original) would be lucky not to have any corrosion or other damage leaving their performance somewhat lacking.
It sounds also like your charging system wasn't hard failed, as it was charging on the ground.
This is speculation here but I'm guessing that the AME charged your battery, found it still didn't crank over properly even with ground power or boost, changed out your starter (possibly erroneously) then found some cables overheating somewhere in the circuit between battery and starter.
Once the engine was starting properly, your intermittent charging problem couldn't be replicated on ground, so a logbook entry was made for the work performed and you went on your way, just to have it fail on you again.
This was the point where the AME was in a thankless position; if he started going through the system with a fine toothed comb, looking for the hidden problem that was not presenting at the moment, the hours rack up. If he started guessing which component may be bad and changed a component to see if it fixes the problem, he's accused of applying the shotgun approach to troubleshooting. If he does nothing and lets you go flying only to have the problem reappear, he's seen as incompetent or negligent.

Why it would fail in the air and not on the ground? That's where the guessing is likely to start, as it's hard to use a multimeter inside the cowl in flight. Vibration, airflow or engine torque in flight pulling a wire that's more relaxed on the ground causing a bad connection? Heat soaking affecting some tired component?

Anyways, I hope you’ve found the end of the tunnel on this snag.

[torquey401]

it's hard to use a multimeter inside the cowl in flight.

Many GPS's have the ability to display input voltage to the unit. Many aircraft have a cigarette lighter that is convenient to use as a test point. Princess Auto sells a nice little down and dirty 12 volt charging system analyzer (it's even on sale).

The ammeter only indicates whether the battery is charging or discharging. Volts indicate if the alternator is supplying voltage to the bus or not. Depending on the aircraft and the charging system installation, lots of troubleshooting can be done. Definitely need more info. I hope the pilot is sharing more with the AME.

PS Google can be your friend!

[GyvAir]

it's hard to use a multimeter inside the cowl in flight.

Many GPS's have the ability to display input voltage to the unit. Many aircraft have a cigarette lighter that is convenient to use as a test point. Princess Auto sells a nice little down and dirty 12 volt charging system analyzer (it's even on sale).

The ammeter only indicates whether the battery is charging or discharging. Volts indicate if the alternator is supplying voltage to the bus or not. Depending on the aircraft and the charging system installation, lots of troubleshooting can be done. Definitely need more info. I hope the pilot is sharing more with the AME.

PS Google can be your friend!

You may be able to somewhat confirm the nature of the snag by knowing your voltage, but that's not going to tell you which part of the charging system is at fault when it's not working in flight, is it?
That PA thing looks like it's nothing more than a voltmeter.

[CID]

Yes, its a good idea for a pilot to know his aircraft's systems but he/she should't use that knowledge to circumvent operating procedures or perform maintenance until such time they have an adequate level of understanding. That's what I meant when I said a "little" knowledge is dangerous. Thorough knowledge on the other hand is perfectly safe.

Case in point? The Colonel stated:

I can't believe the problems people have with simple 12VDC
electrical charging systems in light aircraft.

There's no such thing. The quiescent voltage of the battery is 12 VDC however the charging system must be delivering current at a higher current or no charging will occur.

So some that have been shamed by that statement may be inclined to run out and measure the voltage on their airplane and be aghast that they measure 14.5 volts (or some other voltage prescribed by the OEM) and start replacing everything starting with the battery.

That may sound far fetched but I think it makes a valid point. A "little" knowledge is a dangerous thing.

[iflyforpie]

Yes, its a good idea for a pilot to know his aircraft's systems but he/she should't use that knowledge to circumvent operating procedures or perform maintenance until such time they have an adequate level of understanding. That's what I meant when I said a "little" knowledge is dangerous. Thorough knowledge on the other hand is perfectly safe.

Case in point? The Colonel stated:

I can't believe the problems people have with simple 12VDC
electrical charging systems in light aircraft.

There's no such thing. The quiescent voltage of the battery is 12 VDC however the charging system must be delivering current at a higher current or no charging will occur.

So some that have been shamed by that statement may be inclined to run out and measure the voltage on their airplane and be aghast that they measure 14.5 volts (or some other voltage prescribed by the OEM) and start replacing everything starting with the battery.

That may sound far fetched but I think it makes a valid point. A "little" knowledge is a dangerous thing.

Really, a pilot is going to put a multimeter to a plane, and then measure 14.5 or 13.5 volts... with the plane running.... and then by themselves with no AME license start changing out parts (or duping an AME into randomly changing stuff for them... I know of several who would comply gladly as the bills start piling) because somewhere along the line they got the idea that one or two volts too high is bad in what is described at a 12 volt system (like a 24 volt system that is 28 volts or a 110V system that happens to be 120V)?

Pilots. Learn as much as you can. Knowledge is never wasted. It might save you a buck or two and it might even save your life.

[CID]

I've almost seen it all. I've seen AMEs with "a little knowledge" replace parts because of a hunch based on a shaky understanding of the system. Read the original post. That AME seems to fit that description.

If you're going to do maintenance or troubleshoot something, you should have a complete knowledge of the system and the components or you're generally wasting your time.

Remember this is just my opinion. You don't have to agree.

[torquey401]

You may be able to somewhat confirm the nature of the snag by knowing your voltage, but that's not going to tell you which part of the charging system is at fault when it's not working in flight, is it?

You'd be surprised what you can figure out when you know what the volts are doing and how the system is supposed to operate.

That PA thing looks like it's nothing more than a voltmeter.

Yep!

[GyvAir]

You'd be surprised what you can figure out when you know what the volts are doing and how the system is supposed to operate.

OK, I'll bite.

In a single alternator system, I'm not sure how much more you're going to learn from knowing system voltage in flight that you wouldn't be able to extrapolate from watching the ammeter, but I'd be genuinely happy to learn something new. Please do elaborate.

[Colonel Sanders]

The quiescent voltage of the battery is 12 VDC however the charging system must be delivering current at a higher current or no charging will occur.

http://en.wikipedia.org/wiki/Pedant

[GyvAir]

The quiescent voltage of the battery is 12 VDC however the charging system must be delivering current at a higher current or no charging will occur.

http://en.wikipedia.org/wiki/Pedant

Best two laughs of the day in one post!

Searching for the right word though.... Ironic? Paradoxical? Somebody help me out here?

[dashx]

I think I found a mechanic that might be able to fix your problem:



Turns out he's a pilot too (and how many pilots can say they can fly a car....)

Sorry I just could not resist ........

[torquey401]

I've seen more than one ammeter that would not indicate properly. Using a simple voltmeter can verify things simply and easily. The cigarette plug in "analyzer" or GPS display is simple and cheap and can give the pilot more info to give to his AME for troubleshooting. Voltage is how an alternator is controlled. I personally care to know what the volts are doing when troubleshooting. My .02.

[CID]

So the DC generating system in a light aircraft is simple and you misrepresent one of the basic attributes that you need to troubleshoot the system. All in an attempt to convince pilots to troubleshoot stuff themselves. i correct it and you fire back an insult.

That is the way this forum works. And that`s why people get fed up, Sad. Pathetic. Look those words up and you`ll see a picture of a Pitts flying under a bridge.

Again, a `little`information is dangerous and pretty much anything that gushes from Hedley or Colonel Sanders is best ignored. My opinion.

[GyvAir]

torquey401:

When my wife calls me from the side of the freeway to tell me that on the way back from the mall, she thought the headlights were getting dimmer and that the AC and mp3 player quit working and then the stupid car started running rough and finally quit in the fast lane – and oh yeah, there was this battery shaped light between the speedo and the tach that came on shortly after leaving the house and stayed on all day until the car died, but it’s not on now – I’m not real worried what the actual voltage curve looked like during the drive that day.

(All characters and events depicted in this post are purely fictional, even those based on real people or events)

[Colonel Sanders]

For some reason, chicks

- never check fluid levels
- never check tire pressure (or notice flats)
- never notice lights on the dash

They have guys to do that for them.

[DonutHole]

I've seen more than one ammeter that would not indicate properly. Using a simple voltmeter can verify things simply and easily. The cigarette plug in "analyzer" or GPS display is simple and cheap and can give the pilot more info to give to his AME for troubleshooting. Voltage is how an alternator is controlled. I personally care to know what the volts are doing when troubleshooting. My .02.

Im by no means an expert.. but I was under the understanding that the voltmeter in a gps will just tell you whether or not your battery voltage is static or draining.

I think I heard that there are a few components in the system, like an overvoltage control relay that takes the gen/alt offline if the voltage being fed back to the battery exceeds a predetermined amount. I also think I read somewhere that the voltage regulator controls the voltage (or is it resistance?) into the field which helps determine the final output of the generator/alternator.

Without knowing the field voltage, or if the overvoltage regulator is supplying the voltage regulator with power, how would you go about determining anything other than 'your battery is dying?'

[torquey401]

I was under the understanding that the voltmeter in a gps will just tell you whether or not your battery voltage is static or draining.

That was the point. Sorry that I did not make my point clearer. The pilot could easily find out what the battery voltage is when on the ground before start, after start, during run-up, at take-off, during climb, during cruise, during descent, etc, etc, etc. And most importantly when the fault occurs. It is a more accurate and reliable indication than relying on the ammeter alone. You have to know where the ammeter is wired in to understand what it is telling you. A pilot can use his GPS or a simplr plug in to find out more accurate and reliable information to give to the AME when it comes time to troubleshoot and fix the problem.

If you want to troubleshoot in the fast lane of a highway vs getting the vehicle to a safe location and then start fixing, go right ahead!

Since this whole thread started about a Piper Cherokee with an alternator problem, the original poster may want to check out http://www.nflite.com/ChargingSystem.html. Hope it can help.

[GyvAir]

I think we agree more than we disagree. More information - to a point - is usually a good thing. I've just never been hindered in troubleshooting a charging system by not knowing in-flight bus voltage, even when chasing an intermittent fault.

Thanks for the charging system link. That's a good article that pilots and AMEs alike could learn something new from.

Troubleshooting a dead charging system on a car on the side of the freeway? Don't know where you got that from. I'd even sacrifice a tire/rim or a towing charge rather than hang my ass out in 135km/h traffic to change a tire on an urban section of freeway, like I see a disturbing number of people try to do. You're not much safer standing in front of or behind a car in that situation.

No tongue in cheek here: In a system with the ammeter wired as a load meter as shown in the article, is there a likely scenario where you would see a negative indication on the meter?

[torquey401]

In a system with the ammeter wired as a load meter as shown in the article, is there a likely scenario where you would see a negative indication on the meter?

I doubt it. Maybe shorted diodes, but that would be pretty rare.

Troubleshooting a dead charging system on a car on the side of the freeway? Don't know where you got that from.

I got the impression from:

When my wife calls me from the side of the freeway to tell me that on the way back from the mall, she thought the headlights were getting dimmer and that the AC and mp3 player quit working and then the stupid car started running rough and finally quit in the fast lane – and oh yeah, there was this battery shaped light between the speedo and the tach that came on shortly after leaving the house and stayed on all day until the car died, but it’s not on now – I’m not real worried what the actual voltage curve looked like during the drive that day.

I apologize if I mis-took your comment.

I'm only trying to illustrate how I would go about chasing a problem such as this. Like in most things in life, others may have a different approach. In the end, as long as the things get fixed and everyone is safe, then the job is done.