1969 Piper Cherokee alternator?

[jmarine225]

During a preflight yesterday, I realized my alternator was not charging at all. Output breaker popped and ammeter was dead. Appeared I was running on the battery only as the volt meter for a cigarette lighter charger started at 11.5 and went down to 10.3 before I shut it down. Tried a few different things to resolve it with no results. Any idea what alternator is the replacement or how I could find out? Also my AP told me it’s fine to fly it down to him (30 minute flight) as is, which I’m a little leary on.

 

[RyanB]

Any idea what alternator is the replacement or how I could find out? Also my AP told me it’s fine to fly it down to him (30 minute flight) as is, which I’m a little leary on.

Get one of the Plane Power lightweights. It’ll run you ~$800 plus labor.

 

[Bell206]

Output breaker popped and ammeter was dead.

May want to check the reason for the popped CB before your next flight.

 

[jmarine225]

May want to check the reason for the popped CB before your next flight.

the way I understand the electrical system as per the POH, if the output from the alternator isn’t adequate, it will pop the alternator output circuit breaker, then everything functions off the battery. When I push the breaker back in, there is no power and it pops again, reverting back to the battery.

 

[jmarine225]

Get one of the Plane Power lightweights. It’ll run you ~$800 plus labor.

thanks for the advice. Any idea on a model number or how to find the correct one for my plane? They are all listed by serial number or model number only.

 

[RyanB]

thanks for the advice. Any idea on a model number or how to find the correct one for my plane? They are all listed by serial number or model number only.

Your A&P will know, but there’s likely more going on than a bad alternator. Sounds like some troubleshooting is in order here.

 

[Bell206]

it pops again

FYI: the CB also tends to pop when there is a fault/short in the wire which is CB's primary purpose. So which reason is it, a short or SOP?

 

[Domenick]

Troubleshoot before replacement. It may be the belt, a broken mount, a loose wire/cable, ...

 

[jmarine225]

Yeah I’ll have him look at it. The belt is intact and has tension on it. I guess we shall see. Any thoughts about flying it as is?

 

[Bob Noel]

... Any thoughts about flying it as is?

I, for one, wouldn't fly it without knowing why the breaker pops and the alt isn't working, and having it fixed.

Why would you need to fly it?

 

[Magman]

My thought would be to charge the batt ( preferably out of aircraft)

and fly to your Tech if belt tension normal.

It could be several things and also find new sources of joy with cowl off.

That could entail multiple trips by your Tech.

Minimize electrical load once airborne. Ie Pitot Heat and Land Lite OFF.

 

[Doc Holliday]

So a possible electrical system short, and the advice is to charge up the battery and go fly for a 30 minute trip?

Yea, I mean, what could possibly go wrong?

 

[JAWS]

Any thoughts about flying it as is?

It is really easy to say "it is fine to fly as is" when the person saying it has zero liability in the actual decision.

From this side of the internet, a popped main circuit breaker is not a typical failure. If the plane needs to travel to be looked at, legally a ferry flight is needed. Would need to consider the airspace, comms, navigation, etc.

Good luck.

 

[Doc Holliday]

It is really easy to say "it is fine to fly as is" when the person saying it has zero liability in the actual decision.

From this side of the internet, a popped main circuit breaker is not a typical failure. If the plane needs to travel to be looked at, legally a ferry flight is needed. Would need to consider the airspace, comms, navigation, etc.

Good luck.

And an inspection by an A&P to insure the aircraft is safe for the flight.

So if the A&P is already there, and has inspected the aircraft, why not just go ahead and fix it?

Oh wait....I know...”That would be expensive”.

 

[murphey]

And an inspection by an A&P to insure the aircraft is safe for the flight.

So if the A&P is already there, and has inspected the aircraft, why not just go ahead and fix it?

No, the AP is a 30 min flight away.

 

[Doc Holliday]

No, the AP is a 30 min flight away.

Not if he gets a ferry permit.

But hey, just get advice from SGOTI, charge the battery and go launch.

A 30 minute flight is what? 50-60 miles? An hour drive?

 

[Dan Thomas]

the way I understand the electrical system as per the POH, if the output from the alternator isn’t adequate, it will pop the alternator output circuit breaker, then everything functions off the battery. When I push the breaker back in, there is no power and it pops again, reverting back to the battery.

You are misreading the POH. An underperforming alternator won't pop the breaker unless there's a serious overload or short somewhere.

Charging it and flying it is what one would do to save a life. To do it to save a couple of hour's A&P commute time is foolish, and besides that you don't know what further damage you're doing by flying it. If the alternator has just worn out its brushes, you need a $20 set of brushes. You keep running it and the brushes pop out of their holder and the springs behind them arc against the slip rings and chew them up and now you need a new alternator.

 

[Magman]

I understand where Dan and Doc are coming from.

My post reflects a little different as circumstances may vary and this is what I

would do. Not tell someone what to do.

OP implies that his A & P is reluctant to travel to his location.

Could be a lot of reasons for this.

It can be a rude awakening to find that everyone does not play nicey-nicey.

Will the A & P be allowed on the premises?

Does the A & P have to produce proof of insurance with the airport / FBO

as additional insured?

Does the A & P have the twice per year required TSA Training?

Since this would likely be addressed outside; does the A & Ps car have the required

sticker that allows access to the ramp? Could be a long way to carry tools.

Ramp fee? A Skyhawk was doing traffic show when down flap cable broke.

The pilot elected to land at nearby big airport. On the ground one side

with motor retracted normally. The other was held up in retracted position by;

you guessed it, Duct Tape in order to ferry. Skyhawk owner was informed if I set one foot

on the ramp the $300 Ramp Fee applied. And that was 20 years ago.


Local FSDO does not issue Ferry Permits. That is done by a DAR. ( Designated

Airworthiness Representative)

So for me to get a Ferry Permit (Special Airworthiness Cerificate) I have to

send a copy of my Ferry sign off and assure the US Registration is current.

Then the DAR will schedule the trip. DAR states he is bound to “ lay hands”

( his words) on the aircraft before issuing the Special Airworthiness Certificate.

Since the DAR is a civilian he does charge a reasonable fee plus mileage to travel

to- from the aircraft.

Of course this is all in the name of some sort of “ Safety “. So it must be good?


I was moving a Cherokee after some clown had addressed an Alternator problem.

When moving the prop I discovered a bolt was installed

incorrectly and jam the Alternator so the prop would not turn.

I cut the Belt and walked about 200 ft to the FSDO. maybe GADO?) and

obtained a verbal Ferry Permit ( ok - go ahead ) to the grass strip a short flight

away with electrics off after takeoff. Is the Statute of Limitations expired for

my dealings in Weapons of Mass Destruction?


if you don’t have to deal with some of this you should really consider yourself

very lucky!

 

[Doc Holliday]

You must have the only FSDO in the country that won’t issue a ferry permit.

 

[Bell206]

OP implies that his A & P is reluctant to travel to his location.

This reason, along with your other examples, is zero reason to fly an unairworthy aircraft. Period.

Local FSDO does not issue Ferry Permits. That is done by a DAR.

Agree 100% with Doc. And I’ve questioned you on this in the past. What FSDO? I’d like to call them.

DAR states he is bound to “ lay hands”

Really? Yet it’s rare, if non-existent, to see an FAA ASI “lay hands” on a ferry permit aircraft. The last 6 ferry permits I signed-off on were done via phone and email... and no visit from the ASI. What is so special about your FSDO that they will not perform the same? If it were me I'd be on the horn with the FSDO Office Manager or above to find the answer.

 

[rotormatic1]

DAR’s are required to do the safety for flight inspection for ferry flights... ASI’s are only required to do the inspection if an aircraft is damaged, otherwise, the ASI can delegate the safety for flight inspection to a certificated person (mechanic or repair station). A recent change is the ASI needs to review the log entry for the inspection before issuing the permit.

 

[Magman]

So a piece of paper makes all better?

You get a Ferry Permit because an airplane is not airworthy.

The paper will not fix that.

It will however; allow movement to a place where proper repairs can be made.

I have had no problems getting Field Approvals and Ferry Permits in the past.

The further back you go the less effective communications were.

When was the last time you used the Telegraph system?

However; things were a lot less formal and you could get things done.

Another concern is that some insurance policies require an additional

rider for a Ferry Permit. Won’t hurt to check.


Anyone that names particular persons or facilities on a Recreational Forum is crazy.

If you don’t believe me it’s not a big deal.

I have no idea of how many folks have to put up with some of these policies

but that’s not important to me . As I said; “ Consider yourself lucky if you don’t

have to deal with this,” Next time I get a hard copy on this I’ll send it to you.

I’m not “ The Administrator” so I can’t answer the “ why this way” question.

When the DAR says he has to “ lay hands” what choice do I have but to believe

him? Prior to a few years ago FSDO policy was the same as you state.

There is no burning desire for me to try to convince FAA that they are wrong so

why would I call?

Sometimes I say I was just barely an A & P.

A little earlier and it would have been an A & E.

The difference being the “ Anything. & Everything “

seemed to have a lot more latitude in decision making.

 

[Albany Tom]

Just a pilot with a bit of electrical knowledge. If it were mine, and I could determine that with the master switch off there was 0 load on the battery, and everything seemed mechanically OK with the alternator, I'd get a ferry permit and fly it with the master off. Charging the battery before the flight. If there's no way to fly it without electrics (you're under a class B or something), I wouldn't move it until the electrical system is fixed. 10.7v on a 12v lead acid battery is dead. Depending on the temperature, it should be 12.6 fully charged, no load. My bet, matching others on here, is that you have something else going on besides the alternator...might even be the battery itself.

Reading what I just wrote, it couldn't hurt to charge and test that battery as a first step. Pretty sure that's something you can do yourself as a maintenance item.

 

[Doc Holliday]

So a piece of paper makes all better?

You get a Ferry Permit because an airplane is not airworthy.

The paper will not fix that.

It will however; allow movement to a place where proper repairs can be made.

I have had no problems getting Field Approvals and Ferry Permits in the past.

The further back you go the less effective communications were.

When was the last time you used the Telegraph system?

However; things were a lot less formal and you could get things done.

Another concern is that some insurance policies require an additional

rider for a Ferry Permit. Won’t hurt to check.


Anyone that names particular persons or facilities on a Recreational Forum is crazy.

If you don’t believe me it’s not a big deal.

I have no idea of how many folks have to put up with some of these policies

but that’s not important to me . As I said; “ Consider yourself lucky if you don’t

have to deal with this,” Next time I get a hard copy on this I’ll send it to you.

I’m not “ The Administrator” so I can’t answer the “ why this way” question.

When the DAR says he has to “ lay hands” what choice do I have but to believe

him? Prior to a few years ago FSDO policy was the same as you state.

There is no burning desire for me to try to convince FAA that they are wrong so

why would I call?

Sometimes I say I was just barely an A & P.

A little earlier and it would have been an A & E.

The difference being the “ Anything. & Everything “

seemed to have a lot more latitude in decision making.

Does someone here know where to find a translator app for this?

 

[William Pete Hodges]

During a preflight yesterday, I realized my alternator was not charging at all. Output breaker popped and ammeter was dead. Appeared I was running on the battery only as the volt meter for a cigarette lighter charger started at 11.5 and went down to 10.3 before I shut it down. Tried a few different things to resolve it with no results. Any idea what alternator is the replacement or how I could find out? Also my AP told me it’s fine to fly it down to him (30 minute flight) as is, which I’m a little leary on.

The reason your AP suggested this is two-fold. 1. An electrical system is not necessary for flight safety or for sustained flight in most small airplanes. 2. He wants to put it in the shop where he has everything he needs to properly TS and repair it. I had a similar problem in my '68 Cherokee, and went through 3 rebuilt alternators with bad rotors before finally getting it resolved. Mine did not pop the breaker because the main diodes in the alternator were not shorted. Charge the battery, leave the alternator breaker off, start up and fly down there VFR with most of the electrical system turned off. Run the transponder and 1 radio. You'll be fine.

EDIT: I'd have him order a new or rebuilt alternator and have it on hand before I flew down. He should be able to replace it while you wait. Good luck.

 

[Matthew Rogers]

Does someone here know where to find a translator app for this?

You have to type it out using a typewriter on an actual piece of paper. One you do that, it makes more sense. But only if the "D" key sticks every 3rd time and when you press "H", both the H and J type at the same time.

 

[Bell206]

So a piece of paper makes all better?

You get a Ferry Permit because an airplane is not airworthy.

The paper will not fix that.

It will however; allow movement to a place where proper repairs can be made.

I have had no problems getting Field Approvals and Ferry Permits in the past.

The further back you go the less effective communications were.

When was the last time you used the Telegraph system?

However; things were a lot less formal and you could get things done.

Another concern is that some insurance policies require an additional

rider for a Ferry Permit. Won’t hurt to check.


Anyone that names particular persons or facilities on a Recreational Forum is crazy.

If you don’t believe me it’s not a big deal.

I have no idea of how many folks have to put up with some of these policies

but that’s not important to me . As I said; “ Consider yourself lucky if you don’t

have to deal with this,” Next time I get a hard copy on this I’ll send it to you.

I’m not “ The Administrator” so I can’t answer the “ why this way” question.

When the DAR says he has to “ lay hands” what choice do I have but to believe

him? Prior to a few years ago FSDO policy was the same as you state.

There is no burning desire for me to try to convince FAA that they are wrong so

why would I call?

Sometimes I say I was just barely an A & P.

A little earlier and it would have been an A & E.

The difference being the “ Anything. & Everything “

seemed to have a lot more latitude in decision making.

??? A simple "no" would have sufficed if you didn't want to answer the question.

When was the last time you used the Telegraph system?

1998. CAM -- Bolivia. The airport weather reports were sent/received via code and telegraph then. It was my 15 seconds of infamy when the airport manager let me send the last line of the noon weather report. You?

 

[Domenick]

...
EDIT: I'd have him order a new or rebuilt alternator and have it on hand before I flew down. He should be able to replace it while you wait. Good luck.

Without any troubleshooting?

 

[William Pete Hodges]

Without any troubleshooting?

1. The blown breaker indicates an alternator problem. 99% likely.
2. Leaving the breaker open is not causing further electrical issues as there is no other smoke or signs of electrical distress.
3. The battery is now the only power source and is of limited value
4. The battery does not run the engine, any engine systems except boost pump, and does not run flight controls. The boost pump works, right?
5. The travel time to the mechanic is a short fly, well within sustainable flight limits.
6. You really going to consider not replacing the alternator after this? Likely it has 2 or more shorted stator diodes.
7. The prop has to be removed to remove the cowling and replace the alternator.
8. Alternator power is not blowing the breaker. Battery power is.

Been there, done that. No regrets YMMV

 

[jmarine225]

1. The blown breaker indicates an alternator problem. 99% likely.
2. Leaving the breaker open is not causing further electrical issues as there is no other smoke or signs of electrical distress.
3. The battery is now the only power source and is of limited value
4. The battery does not run the engine, any engine systems except boost pump, and does not run flight controls. The boost pump works, right?
5. The travel time to the mechanic is a short fly, well within sustainable flight limits.
6. You really going to consider not replacing the alternator after this? Likely it has 2 or more shorted stator diodes.
7. The prop has to be removed to remove the cowling and replace the alternator.
8. Alternator power is not blowing the breaker. Battery power is.

Been there, done that. No regrets YMMV

In regards to this response, are you saying the alternator is not functioning and I’m running off the battery, which causes the alternator output breaker to trip? That’s as it seems to me as my voltage was dropping lower as it was running. Tried doing a run up to see if that would kick the alternator in to produce more power and nothing. Plus no output on the ammeter at all. The breaker thing is what confuses me. Why would that breaker trip if the alternator was bad?

 

[William Pete Hodges]

In regards to this response, are you saying the alternator is not functioning and I’m running off the battery, which causes the alternator output breaker to trip? That’s as it seems to me as my voltage was dropping lower as it was running. Tried doing a run up to see if that would kick the alternator in to produce more power and nothing. Plus no output on the ammeter at all. The breaker thing is what confuses me. Why would that breaker trip if the alternator was bad?

No.

1. Alternator is not working, so no power source other than battery.
2. Breaker is tripping because alternator is shorted and battery is backfeeding the short.

 

[William Pete Hodges]

A DC charging alternator is a 3 phase AC generator in y configuration. Each phase feeds output though a full wave bridge rectifier consisting of 2 power diodes. One positive and one negative making 6 power diodes total. If one of each shorts there is a direct short from B+ to B- ground. The battery sees this and feeds it at high current, tripping the breaker.

There is also a rotor, but it should only pull a small amount of amps or less. If the rotor opens or the regulator fails, the alternator stops charging but no short across the output. If one diode fails it will still charge but the output will be reduced and noisy with harmonics. If more fail a dead short of high Amp capacity exists and battery power blows the breaker. The battery can feed more than 300 Amps on the short.

 

[jmarine225]

No.

1. Alternator is not working, so no power source other than battery.
2. Breaker is tripping because alternator is shorted and battery is backfeeding the short.

So with this being said, you are figuring I need an alternator replacement? Belt is good and has tension on it.

 

[Bell206]

Been there, done that. No regrets YMMV

Curious. So after following your 8 step alternator troubleshooting method the OP installs a new alternator and the output CB still pops, what will you recommend to change next?

 

[BoButt]

The only time I have been denied a ferry permit was by an officious FSDO person requiring all AD's were complied with. Once a couple FSDO guys, one my PMI wanted to inspect the aircraft. It had no transponder and the gear was to be secured down and locked. and I was taking it to a busy Class C airport. I think they just wanted an excuse to have lunch at our airports Barf and Belch.

Regarding the suggestion for the PP alternator; Consider it requires twice the amperage of the old style. There is no free lunch. The original electrical system is often negatively affected. You already have unknown issues. Make sure they are resolved and all connections and wiring is ship shape.

As well as starting the engine,the battery is a back up device in case of loss of power. A fully charged battery should provide half an hour. Judicious use, more.

 

[Bell206]

requiring all AD's were complied with.

FYI: Unless an open AD has a provision for the issuance of SFP, all ADs are required to be complied with for a ferry flight with most FSDO's requiring a note that all ADs are complied with in the SFP "safe for flight" logbook entry.

 

[rotormatic1]

AD’s don’t always have the provision. After 2002, AD’s will state you can’t ferry the aircraft. The provision moved to the rule.

§ 39.23 May I fly my aircraft to a repair facility to do the work required by an airworthiness directive?
Yes, the operations specifications giving some operators authority to operate include a provision that allow them to fly their aircraft to a repair facility to do the work required by an airworthiness directive. If you do not have this authority, the local Flight Standards District Office of FAA may issue you a special flight permit unless the airworthiness directive states otherwise. To ensure aviation safety, FAA may add special requirements for operating your aircraft to a place where the repairs or modifications can be accomplished. FAA may also decline to issue a special flight permit in particular cases if we determine you cannot move the aircraft safely.

 

[BoButt]

FYI: Unless an open AD has a provision for the issuance of SFP, all ADs are required to be complied with for a ferry flight with most FSDO's requiring a note that all ADs are complied with in the SFP "safe for flight" logbook entry.

Well sorta, but that was twenty years ago.

 

[William Pete Hodges]

Curious. So after following your 8 step alternator troubleshooting method the OP installs a new alternator and the output CB still pops, what will you recommend to change next?

Not likely the problem will persist after changing the alternator, but that is why you test the alternator for cause of failure when you replace it. If the breaker is tripping either a short exists or the breaker is bad. The short could be in the wiring (not likely but possible) or in the alternator (very likely). If the alternator is shorted bad enough to trip a 35A breaker it will test bad with a low ohm ohmmeter or diode tester. Or you could simply wire a hot battery to it on the bench and watch the sparks fly. It is not really hard to figure this out in the shop. It is nearly impossible to figure it out from your arm chair.

Charge the battery, keep the breaker off, and fly it VFR to the shop.

 

[Bell206]

It is nearly impossible to figure it out from your arm chair.

And thats my point. You've "figured it out" from your arm chair keyboard per your posts above to the point the OP is asking you follow up questions. You've got the fault at 99% on the alternator without even seeing the aircraft and are so certain you've told the OP to buy another alternator to have on hand. I've made a lot of money fixing electrical problems on aircraft to where this problem could be as simple as the CB is old and trips at a lower amperage based on what the OP has stated. Yet you'd have the OP spend $100s on a new alternator, fly it illegally, and then have to explain to him why he needs a new CB as well. Makes no difference to me except I'd hate to see the OP possibly damage his new alternator without proper troubleshooting by following your advice.But to each their own.