Stranded - AOG

[iflyvfr]

Then again, I'll pass on some "sage" advice of my own that my first instructor failed to mention ... don't wear sandals ... don't prop on loose dirt or sand ... check ALL engine controls yourself and have a deal with the safety pilot that (s)he ONLY gets to touch the mag switch.

Jim

I will say this about sandals. A lady I know was wearing flip flops in her Cub and wrapped it around a windsock pole when they got tangled in the pedals.

So, I don't wear flip flops.

 

[tmyers]

Hand propping as part of ppl training. Would make for a good poll so Jim would know how silly that comment was.

Sent from my HTC6525LVW using Tapatalk

 

[Henning]

I will say this about sandals. A lady I know was wearing flip flops in her Cub and wrapped it around a windsock pole when they got tangled in the pedals.

So, I don't wear flip flops.

Yep, I kick mine off and fly barefoot if I'm wearing my flip flops, which is about 95% of the time around here.

 

[Dan Thomas]

Thanks for your "sage" advice. If the feller hasn't handpropped, or been taught to, then of COURSE he is out of his league doing so. That's true of anything not only in aviation but most "dangerous" activities in this world.

Second, if he got his certificate without being taught how to handprop an airplane, then I'd suggest he go get some of his money back from his instructor and spend it on training.

Jim

I have been handpropping non-electric airplanes since 1976. I have also handpropped trikes that had bad starters, and absolutely know that I would never assign a newbie to it. I have also handpropped a 185, and would only attempt it again if my life depended on it. I have taught handpropping to some students and was extremely concerned with the nonchalance with which some seemed to treat it, and gave it up. Nonchalance, or a macho attitude, will sooner or later get one chopped up.

How many students have you taught handpropping?

 

[weirdjim]

How many students have you taught handpropping?

Just about the same number I've taught spins and wind triangles with protractor and pencil. I suppose I could go back and count heads from 1970 on, but that seems to be a silly waste of time. I guess in a bit over a kilohour of instruction it has been a couple of dozen.

Quite frankly, for the clown that suggested a "poll" I really don't give a damn about polls or the results. There are lots of instructors out there; go find one that will let you slide by as you wish. And I do suggest that a read of Bach's "School For Perfection" might be on your library list.


Jim

 

[Tom-D]

As Tom siad, the light-across-the-battery test (or a voltmeter) should be done to eliminate the weak-battery factor. Then one can measure voltage drops across all connections, including across the master contactor studs, to isolate the fault.

Voltage DROP TESTs ?? holy cow now your talking electrical black magic to most owners.

 

[Tom-D]

For those of you who believe the engine should be started on a dead battery think of this. the generator or alternator can supply hundreds of amps, the battery will draws many as it can get during charge.

So the battery is dead, you start the engine, what will excite the field in the alternator? answer..Nothing. It will not charge the battery.

The generator on the other hand, will self excite, and go full out put right away. these old generators found on the 0-300 will only run 5-10 minutes at full rated AMPs before the smoke gets out. do you believe it requires more than 10 minutes to re-charge a dead battery?

 

[bnt83]

Quite frankly, for the clown that suggested a "poll" I really don't give a damn about polls or the results.


Jim

More diarrhea of the fingers. You might wanna wash your hands before picking your nose.

 

[Tom-D]

How many students have you taught handpropping?

Every one who asked.

 

[Anticept]

I'd also like to point out, if you use electronic ignition systems, you may not even be able to hand prop, or it will be extremely difficult to do so.

As for teaching hand propping we discuss it, but we don't go to the plane and teach it, nor encourage it. If a plane won't start normally, a renter doesn't need to be trying to start it by hand. Normally we just point them to youtube videos and reading material on the matter.

 

[iflyvfr]

For those of you who believe the engine should be started on a dead battery think of this. the generator or alternator can supply hundreds of amps, the battery will draws many as it can get during charge.

So the battery is dead, you start the engine, what will excite the field in the alternator? answer..Nothing. It will not charge the battery.

The generator on the other hand, will self excite, and go full out put right away. these old generators found on the 0-300 will only run 5-10 minutes at full rated AMPs before the smoke gets out. do you believe it requires more than 10 minutes to re-charge a dead battery?

I think what you're saying Tom is that equipped with an alternator, I'm not going to get a charged battery out of an engine start, which is not my intent or belief. With a generator I would burn it up as it tries to charge a dead battery.

FWIW, the battery was installed 3 years and 51 weeks ago and is a Concorde RG25XC, I misspoke re: brand. Up until last evening, it had never given me a lick of trouble and was (frequently) kept on an aviation BatteryMinder complete with a temp sensor.

 

[mtuomi]

You sure as hell wouldn't get a signoff for me for your checkride without that skill.

Jim

Typical hour-milking CFI talk.

"This is not in the PTS nor will you ever require this, but I won't sign you off unless you pay me $45 an hour to learn this".

 

[Tom-D]

I think what you're saying Tom is that equipped with an alternator, I'm not going to get a charged battery out of an engine start, which is not my intent or belief. With a generator I would burn it up as it tries to charge a dead battery.

FWIW, the battery was installed 3 years and 51 weeks ago and is a Concorde RG25XC, I misspoke re: brand. Up until last evening, it had never given me a lick of trouble and was (frequently) kept on an aviation BatteryMinder complete with a temp sensor.

just don't do it.

when you have discrepancies, get them fixed.

 

[Tom-D]

I think what you're saying Tom is that equipped with an alternator, I'm not going to get a charged battery out of an engine start, which is not my intent or belief. With a generator I would burn it up as it tries to charge a dead battery.

FWIW, the battery was installed 3 years and 51 weeks ago and is a Concorde RG25XC, I misspoke re: brand. Up until last evening, it had never given me a lick of trouble and was (frequently) kept on an aviation BatteryMinder complete with a temp sensor.

What was determined to be wrong. if you have said, I missed it.

 

[N801BH]

What was determined to be wrong. if you have said, I missed it.

I am all ears too....

 

[Tom-D]

Here you are, flying along, having just hand proped the engine to get it started, the AMP meter is showing a full charge rate.

all is good right?

Think of this, what gas is given off while a battery is being charged? isn't this gas captured in the battery box?

Is this a good thing?

How big of a bomb do you like to carry around?

 

[Anticept]

To answer for tom's question: for flooded cell batteries, it's hydrogen gas. When batteries are being charged at a high rate, they give off a lot of hydrogen gas due to electrolysis(?). This is one of the reason car manufacturers strongly recommend connecting the positive first, and removing it last, and attaching the negative to the frame somewhere away from the battery. This way, the spark will not ignite the gas.

They will also gas when being overcharged excessively.

Also, I'm pretty sure it's against regulation to take off without a minimum battery reserve. I'm not exactly sure where this is (I think part 21 or 23, which is enforced by the airworthiness certificate), but I know someone got violated in St Louis for hand propping a plane in front of an FAA ASI and then took off.

 

[Tom-D]

T
Also, I'm pretty sure it's against regulation to take off without a minimum battery reserve.

ah,, no,,, there isn't. lot's of no electric A/C out there.


What's always legal, isn't always safe, what is safe isn't always legal.

FAR 91.205, no battery listed. no battery = no required battery reserve.

 

[Anticept]

ah,, no,,, there isn't. lot's of no electric A/C out there.


What's always legal, isn't always safe, what is safe isn't always legal.

You make me want to go check this . I'll have to make some calls. Admittedly it was hearsay, but it was from a very reliable source. I'll fact check it!

And, I mean for aircraft that have electrical systems you silly

 

[Tom-D]

You make me want to go check this . I'll have to make some calls. Admittedly it was hearsay, but it was from a very reliable source. I'll fact check it!

And, I mean for aircraft that have electrical systems you silly

I'd like to see the reference.

 

[docmirror]

The generators on this engine are rated for a max of 20, 30, or 50 amps. Most likely a stock gen and 30 amps.

Amperage produced in a gen is proportional to the RPM of the engine. At low engine speeds, under 1200RPM the gen will put out a fraction of it's total rated production, maybe 12-15 amps on a 30 amp gen. If an alternator, if the field is energized it will produce rated full amps about 1500RPM, and the max RPM should be kept below 1000.

All battery boxes are vented. If a battery tray the battery cells are vented. Battery fire from hydrogen outgassing is very, very, very rare.

The voltage testing guide from Skytech starter people is really useful. It doesn't take much effort to run through it with a basic multimeter. Just be careful of the prop when running test #3 across the relays.

Don't prop a plane unless you are trained. If you are trained, propping a O-300 is about the most benign engine to hand prop.

If the engine starts after hand propping, run it for about 15-20 minutes, into the wind if poss with the engine below 1200RPM(1000 if alt equipped) and monitor the ammeter, it will show a charge rate of 8-15 amps.

Once it reduces down below ~8 amps at 1200RPM, run it up to static RPM and check it is charging at about 20 amps or better. You can now take off but monitor the ammeter on your trip. If the battery is somewhat discharged, it will gradually reduce charging amps as it flies. If the battery wasn't the problem, it will still show a modest charge rate, maybe 2-5 amps, depending on the rated amps of the gen.

 

[iflyvfr]

What was determined to be wrong. if you have said, I missed it.

Not yet determined. This occurred last night, we are headed there tomorrow after work to hopefully discover the cause.

 

[iflyvfr]

The generators on this engine are rated for a max of 20, 30, or 50 amps. Most likely a stock gen and 30 amps.

Amperage produced in a gen is proportional to the RPM of the engine. At low engine speeds, under 1200RPM the gen will put out a fraction of it's total rated production, maybe 12-15 amps on a 30 amp gen. If an alternator, if the field is energized it will produce rated full amps about 1500RPM, and the max RPM should be kept below 1000.

All battery boxes are vented. If a battery tray the battery cells are vented. Battery fire from hydrogen outgassing is very, very, very rare.

The voltage testing guide from Skytech starter people is really useful. It doesn't take much effort to run through it with a basic multimeter. Just be careful of the prop when running test #3 across the relays.

Don't prop a plane unless you are trained. If you are trained, propping a O-300 is about the most benign engine to hand prop.

If the engine starts after hand propping, run it for about 15-20 minutes, into the wind if poss with the engine below 1200RPM(1000 if alt equipped) and monitor the ammeter, it will show a charge rate of 8-15 amps.

Once it reduces down below ~8 amps at 1200RPM, run it up to static RPM and check it is charging at about 20 amps or better. You can now take off but monitor the ammeter on your trip. If the battery is somewhat discharged, it will gradually reduce charging amps as it flies. If the battery wasn't the problem, it will still show a modest charge rate, maybe 2-5 amps, depending on the rated amps of the gen.

Thanks for the information, I'm going to hunt down the voltage testing guide and bring it with me. I will be surprised if it is the battery but acknowledge it certainly could be. That's one thing that confuses me: the ammeter always showed a nominal charge, even last night. I check it every flight without fail. If the battery were failing, wouldn't the ammeter show a high charge rate after start?

I'll certainly post more after we find out what the problem is. The good news is we have A&Ps at the ready should we need to affect repairs in the field. We won't do anything unsafe or illegal.

 

[docmirror]

Thanks for the information, I'm going to hunt down the voltage testing guide and bring it with me. I will be surprised if it is the battery but acknowledge it certainly could be. That's one thing that confuses me: the ammeter always showed a nominal charge, even last night. I check it every flight without fail. If the battery were failing, wouldn't the ammeter show a high charge rate after start?

I'll certainly post more after we find out what the problem is. The good news is we have A&Ps at the ready should we need to affect repairs in the field. We won't do anything unsafe or illegal.

No, as batteries fail they go through a process of sulfation, where the plates gradually degenerate, and don't have enough surface area to maintain a good charge. The charge rate will actually decrease as the battery ages because it can't take as large, or fast of a charge anymore. Without going into all the details, they just 'wear out', and the chemistry no longer changes it's ionic property.

Go by Oreilly's and get a hydrometer, sometimes called a battery chemical tester. It's a little glassine bulb with a rubber squeeze on the top, and a little dipper neck. Open all the vent caps on the battery, stick the dipper tip into the fluid, squeeze the rubber cap and release to pull the battery fluid up into the glass envelope. There are four little colored balls in the bulb that will give the condition of the battery chemistry by the specific gravity. Check it first thing before you start messing with the electrical stuff. If none of the balls float, the battery is toast. Put the fluid back into the cell and rinse it with some fresh water, then go on to the next cell.

Check the voltage at the battery terminals, and record the voltage. Then go through that Skytech guide. Go back and record the battery voltage again. Compare it to the first reading, it should be pretty close. If it's much lower the battery is in poor condition, but depending on the plates, and the electrolyte, it could possibly be recharged.

Your battery will not blow up as long as the voltage regulator terminals are not stuck closed. The regulator on a generator is one of those black boxes with three wires sticking out of it like you used to see on an old chevy on the fender. It will limit the battery voltage charge to the limit of the charge rate of the battery specifically so it won't overcharge and damage or destroy a battery. They are set at the factory, and are not adjustable. Stuck regulator contacts is very rare.

Once the engine is running, just monitor the ammeter for what looks like normal conditions you are used to. It may require some high charge rate for the first few minutes. If the charge rate pegs on the meter, and stays there, shut the engine off and investigate the regulator, or just disconnect the wires and tape them up until you get home. The generator will not be producing power, so you don't have any electrical to run your panel stuff, leave the master off unless you really need some comm, or txp, or whatever, but conserve battery until you absolutely need it, and then turn on just what you need to be safe(nav, comm, GPS). Be prepared to run out of battery power, and have a backup plan.

 

[Tom-D]

All battery boxes are vented.

Not in the early 172s, they have a cover, two latches, grommets around the cables, and an acid drain tube, that's all.

And the master re-lay mounted to the front of it.

Push your luck if you like, IMHO its not a good idea to give the battery a high rate charge in the box.

Read the ICAs for your battery they will say to remove the battery for charging

 

[docmirror]

Not in the early 172s, they have a cover, two latches, grommets around the cables, and an acid drain tube, that's all.

And the master re-lay mounted to the front of it.

Push your luck if you like, IMHO its not a good idea to give the battery a high rate charge in the box.

Read the ICAs for your battery they will say to remove the battery for charging

That's not an acid drain tube. There is a vapor gap at the top of all flooded lead acid batteries(I presume this isn't a gel or sealed cell type). That little port at the box is the vent.

You're right that it's not a good idea to give any flooded lead acid battery a high charge rate if confined. More for the heat dissipation than the chemical concern. Batteries get pretty warm, even hot under high charge rates, but the regulator will manage it in all cases, provided the regulator contacts are not welded closed. I gave an example of that(pegged ammeter, shutdown), and way to avoid it by keeping the engine below 1200.

 

[Tom-D]

That's not an acid drain tube. There is a vapor gap at the top of all flooded lead acid batteries(I presume this isn't a gel or sealed cell type). That little port at the box is the vent.

His early Cessna 172 battery box has but 1 tube extending from it. that is drain tube it comes out at the very bottom of the box and dumps directly overboard below the fire wall.

Here is the picture, they are exactly the same for the 170 and early 172.

 

[Anticept]

I don't recall a battery box that has a vent tube at the bottom of the box (EDIT: Well look at that, Tom-D ), and I don't think the manufacturer would want it because acid spilling out into the airstream would be quite corrosive to anything it splatters on. The battery boxes do use a vent on the top, and in some installations, it leads into a jar containing baking soda or some other neutralizer for any aersolized or diffused acid (can't think of the right word), before venting overboard. I also believe the battery boxes are designed with a material or coating meant to resist battery acid in case of overflow

As for the boxes being vented for explosion: it is a low chance. Plus, I don't think there is anything in the battery compartment that could even ignite it (well, except in an old king air where the solenoid was installed IN THE BATTERY COMPARTMENT ). Still, if a plane is sitting on the ramp charging the battery before departure, then this could be a bit of a bigger issue... like in a piper or mooney where the battery is installed in the tail cone (mooney) or under the passenger seat (piper).

Interesting discussion

 

[docmirror]

Pretty sure that tube on the bottom is an air break to let fresh air in. There's likely some kind of vent at the top for the vapors to release. Unlikely they would leave it sealed with the vent at the bottom, but it's possible. Or, they use a tube in a tube, and the inner one goes to the top, and outer one at the bottom. Battery venting is pretty basic.

 

[Tom-D]

That's not an acid drain tube. There is a vapor gap at the top of all flooded lead acid batteries(I presume this isn't a gel or sealed cell type). That little port at the box is the vent.

You're right that it's not a good idea to give any flooded lead acid battery a high charge rate if confined. More for the heat dissipation than the chemical concern. Batteries get pretty warm, even hot under high charge rates, but the regulator will manage it in all cases, provided the regulator contacts are not welded closed. I gave an example of that(pegged ammeter, shutdown), and way to avoid it by keeping the engine below 1200.

The deco generator on the 0-300, is a 35 Amp, that is a pretty easy charge rate, but it will be the generator that will fail in flight, at 35 amps the battery will not be close to fully charged in the time allowed by your routine. and the voltage regulator will be charging the battery at a full charge rate of 35 amps. until the battery is above 13.2 volts.
If his 172 has a 50-0-50 gauge the needle will show the 35 amps, If his 172 has the 30-0-30 it will show a full deflection.

Here is another thought about a failing generator on the 0-300. the generator is driven by a gear that is connected to the generator by a simple love connector (2 little rubber blocks held in a cup) when it is over loaded, it destroys itself and falls into the accessory case along with the other gears. When the old Delco generator fails it usually over heats and unsolders the commutator which jambs the rotation of the armature.
I've made several thousand bucks pulling the generator to find pieces of the love connection missing, and then disassembling the accessory case by removing the two mags, the starter, tach cable, just to get to the accessory case then by removing it, to find the parts are in the oil sump, and it must come off too. you can't remove that with the engine in the mount.
Yeah,, go ahead push your luck. we A&Ps need the work.

 

[Henning]

For those of you who believe the engine should be started on a dead battery think of this. the generator or alternator can supply hundreds of amps, the battery will draws many as it can get during charge.

So the battery is dead, you start the engine, what will excite the field in the alternator? answer..Nothing. It will not charge the battery.

The generator on the other hand, will self excite, and go full out put right away. these old generators found on the 0-300 will only run 5-10 minutes at full rated AMPs before the smoke gets out. do you believe it requires more than 10 minutes to re-charge a dead battery?

Many alternators are self exciting as well, however that still doesn't mean you're in a good position if you don't know what is wrong.

 

[weirdjim]

Typical hour-milking CFI talk.

"This is not in the PTS nor will you ever require this, but I won't sign you off unless you pay me $45 an hour to learn this".

My fee is $15 an hour and has been for as long as I can remember. I don't do it for the money, obviously. My engineering feeds my body; my teaching feeds my spirit. You ought to think about it.

Jim

 

[Tom-D]

Pretty sure that tube on the bottom is an air break to let fresh air in. There's likely some kind of vent at the top for the vapors to release. Unlikely they would leave it sealed with the vent at the bottom, but it's possible. Or, they use a tube in a tube, and the inner one goes to the top, and outer one at the bottom. Battery venting is pretty basic.

I'm telling ya there is no venting done in the early 170/172 battery box other than to keep the inside pressure the same as the out side. There is no tube supplying air to the battery box, there is only 1 drain at the bottom of the box. which in many cases I see the plastic tube is turned brittle, broken and the acid has etched the fire wall from that point down to the fuselage skin.
And yes, the battery acid does get all over the belly when it is boiled out at a high rate charge.

 

[Tom-D]

Many alternators are self exciting as well, however that still doesn't mean you're in a good position if you don't know what is wrong.

Show me one STCed for, or a direct replacement for, the 172. there are several solid magnet brushless alternators sold on Spruce, but none are certified as a replacement for the generator on the 0-300/0-200
Now let's stay focused on subject, this isn't some " I got a better idea" thread.

 

[Henning]

Typical hour-milking CFI talk.

"This is not in the PTS nor will you ever require this, but I won't sign you off unless you pay me $45 an hour to learn this".

There two sides to that coin, the longer you are around aviation, the more you realize how incomplete the knowledge base for the PTS is. The PTS sets forth the MINIMUM standard, minimum. Minimum knowledge and skill should never be a goal post in aviation, and it's kinda why SP being bandied about as a "Easier and faster to get" as the reason people choose SP makes me cringe.

In my 40 hrs to PP we covered many things not in the PTS including spins and falling leaf stalls, didn't cost me an extra dime to learn them. Considering it takes 5 minutes to teach someone how to prop up a plane safely, that would be $3.75 at $45hr (although none of my instructors charged me beyond Hobbs). OTOH, I've made a few bucks over the years $20 at a time by propping around a dozen people up.

 

[Tom-D]

There two sides to that coin, the longer you are around aviation, the more you realize how incomplete the knowledge base for the PTS is. The PTS sets forth the MINIMUM standard, minimum. Minimum knowledge and skill should never be a goal post in aviation, and it's kinda why SP being bandied about as a "Easier and faster to get" as the reason people choose SP makes me cringe.

In my 40 hrs to PP we covered many things not in the PTS including spins and falling leaf stalls, didn't cost me an extra dime to learn them. Considering it takes 5 minutes to teach someone how to prop up a plane safely, that would be $3.75 at $45hr (although none of my instructors charged me beyond Hobbs). OTOH, I've made a few bucks over the years $20 at a time by propping around a dozen people up.

It's dangerous to give people just enough education to get them killed.

 

[mtuomi]

There two sides to that coin, the longer you are around aviation, the more you realize how incomplete the knowledge base for the PTS is. The PTS sets forth the MINIMUM standard, minimum. Minimum knowledge and skill should never be a goal post in aviation, and it's kinda why SP being bandied about as a "Easier and faster to get" as the reason people choose SP makes me cringe.

In my 40 hrs to PP we covered many things not in the PTS including spins and falling leaf stalls, didn't cost me an extra dime to learn them. Considering it takes 5 minutes to teach someone how to prop up a plane safely, that would be $3.75 at $45hr (although none of my instructors charged me beyond Hobbs). OTOH, I've made a few bucks over the years $20 at a time by propping around a dozen people up.

I agree with that. But being surprised its not taught, and saying he wouldn't sign a student for the practical test without that seems insane to me.
Definitely something that to me is more in the "can you teach me this" category, rather than "you have to learn this to be a pilot".

 

[Henning]

It's dangerous to give people just enough education to get them killed.

It's not rocket science. Plenty of people walk into props without having propped them up. You can't fix or train someone out of stupid.

 

[Tom-D]

I agree with that. But being surprised its not taught, and saying he wouldn't sign a student for the practical test without that seems insane to me.
Definitely something that to me is more in the "can you teach me this" category, rather than "you have to learn this to be a pilot".

Back in the day, you had to know how to go flying. J-3's for ever

 

[Tom-D]

It's not rocket science. Plenty of people walk into props without having propped them up. You can't fix or train someone out of stupid.

having some one walk into to a prop is a lot different than messing yourself up.
Here ya go sonny, this is your new sports car. that's the gas pedal. push it down to go fast. see ya, have a nice day.