Stranded - AOG

iflyvfr

iflyvfr

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Sep 20, 2013
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1,794
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Columbus, OH
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Display name:
Greg
My beloved 172G is sitting at a strange airport tonight. The wx here was CAVU and I needed fuel so after dinner I departed Bolton (KTZR) straight out for the cheapest gas.

After refueling I pulled the master on and heard the gyros spin up. I grabbed the key and moved it to start and . . .everything shut down. The only thing I hear when I pull on the master switch is a 'clunk' in the engine compartment, which seems to be the master solenoid affixed to the front of the battery box. No power to anything.

I checked the wires on both the master and starter solenoids & they are snug. The battery terminals are too. I have an alternator conversion, the 50 amp circuit for that was pulled and reinserted to no effect. I also have a SkyTec starter. What has failed?

Note: I ate coleslaw last night but do not need a body concealed.
 
How old is the battery?

simple check, place a light across the battery poles, try to start the engine see what the light does. if it was bright with no load, and goes dim when there is a load, the battery is dead. find out why.
 
Tom-D said:
How old is the battery?

simple check, place a light across the battery poles, try to start the engine see what the light does. if it was bright with no load, and goes dim when there is a load, the battery is dead. find out why.
Click to expand...

Old airplanes are fun. Do Tom's test. If the light across the battery stays lit, the master contactor is shot. Very common in old airplanes. The contacts don't even have to get burned--they just oxidize with age. Any resistance on those contacts causes a massive voltage drop when the starter makes its huge current demand.

To make diagnosis harder, it's often an intermittent failure.
 
Dan Thomas said:
Old airplanes are fun. Do Tom's test. If the light across the battery stays lit, the master contactor is shot. Very common in old airplanes. The contacts don't even have to get burned--they just oxidize with age. Any resistance on those contacts causes a massive voltage drop when the starter makes its huge current demand.

To make diagnosis harder, it's often an intermittent failure.
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His aircraft the battery master is not in the start system. the Battery + lead goes directly to the skytech starter. battery master only powers the buss. that controls the start button.
bad connections of the battery terminals could cause this too, they are tight, but high resistant connection and can not carry the AMPS required by the starter.
This is either a bad connection, bad starter, or a bad battery. I'd guess starter, because the master relay is clicking. it usually won't on a dead battery.
 
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The battery is several years old. Gosh, it might be 5+. I've kept it on a battery tender pretty diligently throughout the years, it's a Gill sealed battery FWIW.

No problems with engine start, and AMP meter showed normal charge after start. I'm hoping a new master contactor will be the fix we need. Fortunately my buddy is an electrical engineer, so we will t-shoot and repair with my A&P.
 
iflyvfr said:
The battery is several years old. Gosh, it might be 5+. I've kept it on a battery tender pretty diligently throughout the years, it's a Gill sealed battery FWIW.

No problems with engine start, and AMP meter showed normal charge after start. I'm hoping a new master contactor will be the fix we need. Fortunately my buddy is an electrical engineer, so we will t-shoot and repair with my A&P.
Click to expand...

Do you have the master re-lay that has the clear plastic cover that is held on by a wire bail?
those have contactors that can be replaced.
or do you have the tin can type.
 
iflyvfr said:
No problems with engine start, and AMP meter showed normal charge after start. I'm hoping a new master contactor will be the fix we need.
Click to expand...


You really didn't hear Tom-D say that the contactor is NOT in the circuit for start?

Jim
 
weirdjim said:
You really didn't hear Tom-D say that the contactor is NOT in the circuit for start?

Jim
Click to expand...

If the master re-lay didn't close the starter would not have placed a load on the battery or its terminals.

Starter control is off the master re-lay. Starter rotate/crank the engine is direct to the battery.

every thing worked until he placed a load on the battery, and its connections.

then he tells us, that it started and every thing looked normal? to me that's a bad battery connection.
 
I'd wager that the ICAs for the battery were not complied with at the last annual.

That Gill is not a maintenance free battery.
 
Had something like this recently in a 172 and it was just a failed ground connection.
 
weirdjim said:
You really didn't hear Tom-D say that the contactor is NOT in the circuit for start?

Jim
Click to expand...

I have yet to see any airplane that has the starter or its contactor wired directly to the battery. All the airplanes I've ever worked on had the master contactor controlling everything except the clock and hourmeter, which are on tiny fuses. The pilot needs to be able to shut off any rogue circuit to eliminate fire risk if something shorts.

When I get back to work Tuesday I will check the 172G schematic and educate myself.
 
Dan Thomas said:
I have yet to see any airplane that has the starter or its contactor wired directly to the battery. All the airplanes I've ever worked on had the master contactor controlling everything except the clock and hourmeter, which are on tiny fuses. The pilot needs to be able to shut off any rogue circuit to eliminate fire risk if something shorts.

When I get back to work Tuesday I will check the 172G schematic and educate myself.
Click to expand...

Been awhile since I've flown a G..but I can say for fact that on our M and N models you won't be cranking if the master isn't on.
 
Dan Thomas said:
I have yet to see any airplane that has the starter or its contactor wired directly to the battery. All the airplanes I've ever worked on had the master contactor controlling everything except the clock and hourmeter, which are on tiny fuses. The pilot needs to be able to shut off any rogue circuit to eliminate fire risk if something shorts.

When I get back to work Tuesday I will check the 172G schematic and educate myself.
Click to expand...
Read the installation instructions for the skytch starter.
 
jesse said:
Had something like this recently in a 172 and it was just a failed ground connection.
Click to expand...
That could also be the problem.
The G has the 0-320-/150 horse Lycoming which has the starter under #2 cylinder with a long battery cable with a tin can starter relay. to energize that re-lay you need a live buss. he had that until he over loaded the battery or connections by trying to start.
 
jesse said:
Been awhile since I've flown a G..but I can say for fact that on our M and N models you won't be cranking if the master isn't on.
Click to expand...

That's a fact. he had starter control proven by his ability to engage the starter. the master re-lay was closed.
 
Dan Thomas said:
I have yet to see any airplane that has the starter or its contactor wired directly to the battery. All the airplanes I've ever worked on had the master contactor controlling everything except the clock and hourmeter, which are on tiny fuses. The pilot needs to be able to shut off any rogue circuit to eliminate fire risk if something shorts.

When I get back to work Tuesday I will check the 172G schematic and educate myself.
Click to expand...

this 172 is right at the change over so it may go thru the Master relay first.
http://www.google.com/imgres?imgurl...d=0CCEQMygAMABqFQoTCMTOqMSVjMcCFQx_kgodeLwAQA
 
Tom-D said:
That could also be the problem.
The G has the 0-320-/150 horse Lycoming which has the starter under #2 cylinder with a long battery cable with a tin can starter relay. to energize that re-lay you need a live buss. he had that until he over loaded the battery or connections by trying to start.
Click to expand...

I thought the G was powered by a 0-300. My H is and the H was the last year of the 0-300
 
two posts down... dirty termina1s and or 1ost a ground is my bet.
 
Luvrv8 said:
I thought the G was powered by a 0-300. My H is and the H was the last year of the 0-300
Click to expand...

You are absolutely right, 0-300-C or D which has the master relay on the front of the battery box just like the 170, if it isn't closed, nothing works. the battery cable comes directly off the battery + post to the relay, then off the relay to the starter + post which acts as the connection for the heavy wire to the Buss.
 
iflyvfr said:
My beloved 172G is sitting at a strange airport tonight. The wx here was CAVU and I needed fuel so after dinner I departed Bolton (KTZR) straight out for the cheapest gas.

After refueling I pulled the master on and heard the gyros spin up. I grabbed the key and moved it to start and . . .everything shut down. The only thing I hear when I pull on the master switch is a 'clunk' in the engine compartment, which seems to be the master solenoid affixed to the front of the battery box. No power to anything.

I checked the wires on both the master and starter solenoids & they are snug. The battery terminals are too. I have an alternator conversion, the 50 amp circuit for that was pulled and reinserted to no effect. I also have a SkyTec starter. What has failed?

Note: I ate coleslaw last night but do not need a body concealed.
Click to expand...

Most likely a problem in the solenoid contacts.
 
That sounds a like my car when the battery is dead or plate inside the battery failed.

Do you have the old high current landing lights? If you turn them on are they very dim?

If you can troubleshoot it down to a battery issue the next step is to make some phone calls and ask around and see if anyone on the airport has a battery you can borrow.
 
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SkyTec starters manufactured a couple of years ago had bad solenoids. I had a new ST-5 installed three years ago, and less than a year later the starter would just click, and not turn the engine. Luckily it was still under warranty, and I was stranded at my own field and not elsewhere.

This was a very common problem, I've heard, with SkyTec during that time frame.
 
iflyvfr said:
The only thing I hear when I pull on the master switch is a 'clunk' in the engine compartment, which seems to be the master solenoid affixed to the front of the battery box. No power to anything.
Click to expand...
No power to anything? As in no lights, no radio, no ammeter needle jump, no nutting? Then it's not the starter or anything related to just the starter as some might suggest.

If, as claimed, the battery goes directly to the starter and not through the master and neither the starter or anything else work, then it's probably not the master either.

Battery be dead, or you have a open circuit from the battery or the battery ground.
 
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Tom-D said:
Read the installation instructions for the skytch starter.
Click to expand...

I have installed seven or eight Skytec starters. The original starter cable goes to the starter. There are NO changes to the airframe circuitry.
 
Capt. Geoffrey Thorpe said:
No power to anything? As in no lights, no radio, no ammeter needle jump, no nutting? Then it's not the starter or anything related to just the starter as some might suggest.

If, as claimed, the battery goes directly to the starter and not through the master and neither the starter or anything else work, then it's probably not the master either.

Battery be dead, or you have a open circuit from the battery or the battery ground.
Click to expand...

Everybnody needs to go read the first post. When he pulled the master on, the gyros spooled up, and when he hit the starter eveything shut down. That is a classic voltage-drop situation caused by the starter's low resistance/high current demand, and any resistance between the battery and starter (including a dirty ground), or a weak battery, will do this. In old airplanes it's often a bad master contactor. If it was a bad starter contactor, the gyros wouldn't spool down.

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.
 
Why not just prop it? :dunno: or am I missing something. I started a 150 this weekend with a dead battery.
 
OK, I'll ask a stoopid question ...

Why are you stranded AOG when all you need to do is prop the sumbitch and fly it home where you have the tools and support groups of your home airport?

Thanks,

Jim

(Seems like DFH65 and I had the same exact thought at the same exact time. Sorry for the duplication. jw)
 
weirdjim said:
OK, I'll ask a stoopid question ...

Why are you stranded AOG when all you need to do is prop the sumbitch and fly it home where you have the tools and support groups of your home airport?

Thanks,

Jim

(Seems like DFH65 and I had the same exact thought at the same exact time. Sorry for the duplication. jw)
Click to expand...

If a guy hasn't handpropped, he should stay away from it until he's been trained. Too many inexperienced people have been hurt or killed doing it. Handproppers are a rare breed now.

Darwin is never far off, you know...
 
Dan Thomas said:
If a guy hasn't handpropped, he should stay away from it until he's been trained. Too many inexperienced people have been hurt or killed doing it. Handproppers are a rare breed now.

Darwin is never far off, you know...
Click to expand...

Agree, and there is considerably more room for error on a nosewheel airplane that was designed to start with a starter versus a tailwheel that was designed to be propped. The taildragger means as you pull through you're moving back from the airplane...not so with a nosewheel..and sometimes the prop isn't mounted to be in a good position on the compression stroke as well.

I have probably three to four hundred prop starts under my belt now on tailwheel aircraft that were designed to be started that way. I still consider it a risk and don't much enjoy it.

I probably have 10 or 20 on various 172 class aircraft. I do it if it needs to be done but I wouldn't make a habit of it..and it's just more risky IMO with the less than ideal angle.

I really dislike doing it on a six cylinder nosewheel. It can be done...and I've done it..but..you're just begging for something to go wrong.

I've heard of guys prop starting three bladed six cylinders but pretty sure I wouldn't be trying that unless my life depended on it.
 
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Dan Thomas said:
If a guy hasn't handpropped, he should stay away from it until he's been trained. Too many inexperienced people have been hurt or killed doing it. Handproppers are a rare breed now.

Darwin is never far off, you know...
Click to expand...

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
 
jesse said:
and sometimes the prop isn't mounted to be in a good position on the compression stroke as well.
Click to expand...

On any 4 or 6 banger I've ever propped, I have yet to find one that didn't give me the optimum prop location SOMEWHERE in the cycle of all the cylinders.

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
 
weirdjim said:
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
Click to expand...

I doubt anyone teaches that nowadays.
I sure wouldn't pay my instructor for that nonsense.
 
A 5 year old Gill? That itself could be an indication, battery problem.
 
weirdjim said:
You sure as hell wouldn't get a signoff for me for your checkride without that skill.

Jim
Click to expand...


It's a very rare skill for new pilots.

Many (most?) clubs and FBOs have a specific policy against it.

I'm talking Archers/Arrows/182s here, not a Cub.
 
weirdjim said:
You sure as hell wouldn't get a signoff for me for your checkride without that skill.

Jim
Click to expand...

I'm not going to teach someone how to prop our rentals, no way, no how. If it won't start because of the starter I don't want them flying it until I *KNOW WHY*. That's troubleshooting and systems knowledge they're simply not going to have at the private pilot level.

I have had a rental pilot call me before saying they're stranded and the starter won't start it. In that case I flew another airplane there, told them to take it home, and then did some troubleshooting followed by me ultimately propping it and bringing it home myself.
 
Luvrv8 said:
I thought the G was powered by a 0-300. My H is and the H was the last year of the 0-300
Click to expand...

Absolutely is the Conti O-300 with the contactor the tin can type mounted to the front of the battery box, and the starter contactor on the FW.
 
mtuomi said:
I doubt anyone teaches that nowadays.
I sure wouldn't pay my instructor for that nonsense.
Click to expand...
Yeah I was pretty much by my lonesome and have not been trained to do it. Respect thy prop.

Fortunately my friend is an electrical engineer and works with a lot of equipment, in addition to owning a farm so he's pretty handy with mechanicals and a voltmeter.

I did read some of the information about the SkyTec and have to wonder if that's going to end up being my problem.

We have a plan to go do some testing tomorrow after work and either prop it to get her home or replace the battery if it's the culprit.
 
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