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Looking for Piper drawing #15500 Electrical

Where did you come up with the numbers 60766-2 and 14224012??? Also--what are the numbers that are on each wire in the schematic that you have attached??? Is there a page that is missing that relates to those numbers??




DaCub-DaCub said:
This schematic matches the five jpeg's you posted of Dwg. 15500

There is one change I would take the liberty to make! I disagree with the routing of the starting current load being directed through the master contactor and in series with the starting contactor. This allows for a "single point of failure" something we take efforts to avoid in the electrical supply industry. This electrical design is totally dependant on the functionality of the master. The change would not be hard.

Simply seperate the two solenoids , feed them both batt + and make provision for independant switching of the Start contactor (key Switch).
In other words, eliminate the common wire to each sol (60766-2) and extend (14224012) to supply both solenoids in a parallel (+) feed.
Good luck with the project

PA18_elect_schem.jpeg
Click to expand...
 
Hold those thoughts--I have just found out last Sat that I will need to move some cub parts and two L-5 fuselages out of a hangar next to the one where the cub is located--the hangar sold so now I need to cram two fuselages and more cub parts into the work hangar!!!!

DaCub-DaCub said:
This schematic matches the five jpeg's you posted of Dwg. 15500

There is one change I would take the liberty to make! I disagree with the routing of the starting current load being directed through the master contactor and in series with the starting contactor. This allows for a "single point of failure" something we take efforts to avoid in the electrical supply industry. This electrical design is totally dependant on the functionality of the master. The change would not be hard.

Simply seperate the two solenoids , feed them both batt + and make provision for independant switching of the Start contactor (key Switch).
In other words, eliminate the common wire to each sol (60766-2) and extend (14224012) to supply both solenoids in a parallel (+) feed.
Good luck with the project

PA18_elect_schem.jpeg
Click to expand...
 
cubnut,
Please review Dwg. # 1 of 5 in your previous post.
This is an assembly drawing. Those #'s are assembly part #'s,
The numbers I ref'd 60766-2 and 142240-12 are ASSEMBLY NO'S
The schem. shows numbers that might be Circuit #'s, or Purpose #'s, or Location #'s, or Coupling #'s of a plug.
Your assumption of the existance of an additional list, as a legend, to interpret this document is appropiate, but I don't know of it. In any event, it matters not in the desire to utilize the schem. for the purpose of circuit topology.
If local experienced assistance might not be an option in your project completion, might I suggest, the wonderful benefits both you and your project would recieve from a trip to visit a major cub rebuild community and jaw-bone with the locals.
I probably need not tell you where you can find more projects and infinite quantity of knowledge from individuals who can't resist talk of such and are freindly but, Heven forbid, I would to have say the "A" word. Seriously, I want to convey the best wishes in the move and with your project and do seek experienced electrical assistance.
dC-dC
 
So here is the schematic from the late model (SN1809001 and up).

Electrical Schematic 809001.webp

Don
 

Attachments

  • Electrical Schematic 809001.webp
    Electrical Schematic 809001.webp
    362.7 KB · Views: 362
Hmmmmm! I appreciate you posting this schematic--I will work with it awhile and see what I can come up with.
 
Well that sucks. The 15499 drawing I ordered from Piper matches the schematic I posted for SN1809001 I posted. Except for the addition of a diode across the master solenoid.
 
Drawing #15499

Aerodon said:
Well that sucks. The 15499 drawing I ordered from Piper matches the schematic I posted for SN1809001 I posted. Except for the addition of a diode across the master solenoid.
Click to expand...

Interesting---I wonder which is better to have on hand--the schematic which is from the owners manual or an official Piper drawing???
 
Wondering what, if any advantages there are to using a Master Relay like the later model Super Cubs. Wiring a 1971 model now which has the starter relay and two 30 amp fuses feeding the main buss. I am looking at replacing them with a resetable circuit breaker but trying to decide pros and cons to a master relay. Ideas?
 
Steve Pierce said:
Wondering what, if any advantages there are to using a Master Relay like the later model Super Cubs. Wiring a 1971 model now which has the starter relay and two 30 amp fuses feeding the main buss. I am looking at replacing them with a resetable circuit breaker but trying to decide pros and cons to a master relay. Ideas?
Click to expand...

I can't think of a single reason for a master relay in a stock cub. Those things are needed only if you have very high loads the generator alone can't carry (e.g. landing gear / flap motor, electric hydraulic pumps, etc.).
 
When you turn the master switch off, there are no live wires going any further than the relay. With the double switch you have two live wires all the way to the wing root. Fused yes, but still live. Don
 
Aerodon said:
When you turn the master switch off, there are no live wires going any further than the relay. With the double switch you have two live wires all the way to the wing root. Fused yes, but still live. Don
Click to expand...

That is true: By the same token, you also have a live AND unfused generator wire going there. The solution is to move all that stuff out of the wingroot, not adding a master relay - IMHO.
 
When you turn the master switch off, the voltage regulator is turned off and no output from the alternator, no? Agreed, move power away from the fuel tanks, what were they thinking?
 
Aerodon said:
When you turn the master switch off, the voltage regulator is turned off and no output from the alternator, no? Agreed, move power away from the fuel tanks, what were they thinking?
Click to expand...

Not all master switches cut the generator field. Those that control only a master relay are SPST switches that cut only the ground path to the relay, and a need a separate switch to control the field. You could put both on a single DPST switch, but then you'll loose independent control of your power sources. Either way, you'll still have live, unprotected wiring in the cockpit (unless you put a field c/b ahead of the firewall). Also, a master relay is itself a load on your system.
 
This is a complete rebuild and I have removed the electrical from the wing root. It has the under seat battery and I believe I will install a circuit breaker accessible by the pilot at the battery and not add a master relay to the system. This is a simple electrical system with lights, radio and transponder. I also found out that it takes 3/4 of an amp just to hold the relay closed, this and my experience with failed master relays leads me to ask myself why I would need one. Thanks for all the feedback, as usual you guys made me think of things that I had not.
 
Last edited:
Steve Pierce said:
http://www.bandc.biz/pdfs/420-506_Indexed_Diagram_with_BOM.pdf
Click to expand...

A few things I don't like about B&C's wiring diagram:

Not sure you need them MOV's (but I don't know enough about them or their failure rate).

8 Amps is not much juice. It's probably enough to power a radio and a xponder, or nav/strobes + GPS but not both. Either way, nothing's left to recharge the battery. Normally, the total composite load should be not more than 80% of the generator capacity. Here, it's more like 2-300% (judging from the c/b ratings) without radios.

But what I really don't like is the way the mag switches are combined with the starter circuitry. A right mag switch fried by the starter solenoid power feed can kill that mag. Plus, depending on its proximity to the other mag switch, kill that mag too. Also, the starter is armed whenever the right mag switch is OFF and the left is ON. Normally, these are not issues as long as you don't inadvertently hit the starter button. But they could be with a shorted out MOV across the starter button contacts. Either way, you wont be able to motor the engine with the starter without the left mag switch ON.

- The diagram shows 2 DPST (ON-OFF) switches (Item 8, ) but the BOM lists DPDT ( (ON)-OFF-ON ) switches.

My 2c.
 
Aviator said:
....
- The diagram shows 2 DPST (ON-OFF) switches (Item 8, ) but the BOM lists DPDT ( (ON)-OFF-ON ) switches.

My 2c.
Click to expand...

you failed Schematic reading 101... item number 8 IS a DPDT switch... and each item L & R on schematic is one half/side of THAT DPDT switch shown that way for clarity as separate things......... they probably should have a dashed line box around the two.....
 
Is the master relay an explosion proof switch such that in an emergency with gas all over the place if you turn off the master there wont be any spark as opposed to an open switch?
 
I posted a link to an excellent training manual on switches earlier, but based on some of the bold statements in this thread I can only assume not everyone had a chance to read it. Note that a double throw ON-OFF-ON or (ON)-OFF-ON toggle switch always includes the center OFF position. Otherwise it's an ON-ON or (ON)-ON switch.

So here's that link again.
http://www.aeroelectric.com/Reference_Docs/Switches/CH_Switch_Training_Manual.pdf

qsmx440

They're usually well sealed, so they should keep out fumes and contain any internal arcing. When you turn it OFF you're (usually) just cutting the ground. But if your control wire touches ground somewhere else, it will power up the relay again.
 
Last edited:
I posted the diagram as an example of a simple electrical system. It is how a lot off aerobatic airplanes are wired. The keyed mag switch acheieves what is depicted in the magneto/starter part of this schematic.
 
Sorry, Steve; I thought you were looking for a critique of this wiring diagram for your rebuild. My mistake.:oops:
 
Just a word about installing a stall warning system in a cub.....Don't.....they don't work at the angles you are coming in at with a Borer type prop. My 77 had one installed at the factory. The CB has been pulled on it for twenty years... You can't adjust it enough to not go off, so you get to listen to it forever on final or steep climb-outs...One of the dumbest things Piper ever did to the PA-18.... Who needs a stall warning in a cub anyway? Must have been something the FAA required...
 
Just been asked by our licenced engineer for more details of the wiring diagram for my SuperCub (PA18-150 S/N 18-7509010) which we are completely rebuilding, he needs it for the workpack and as a start point for the additions we are going to need to make (transponder etc)

Have the appropriate one from the handbook also the later schematic.

The query is:

i). Has anyone decoded the supplementary numbers on the schematic, I can deduce that the SWG is listed in one box but what is the other boxed number on the schematic wire.

ii). Am I right in thinking that this is the best we can get, is anything more comprehensive out there for a PA18 wiring diagram?

Kind regards

Stew
 
Stew,

I have developed a CAD version for the wiring digram with my own modifications for the exact configuration as installed. I turned it into a two page drawing, one for electrics, and one for the avionics buss. Electrics have changes like the Plane Power alternator, Maxpulse light switch, strobes, etc. Avionics - your choice.

Some of the Piper drawing numbers are wire size, others are just wire numbers. Hard to differentiate, so I made my drawing more obvious.

I can modify to your exact configuration, send me an email: supercub180@gmail.com Don
 
Stew said:
Just been asked by our licenced engineer for more details of the wiring diagram for my SuperCub (PA18-150 S/N 18-7509010) which we are completely rebuilding, he needs it for the workpack and as a start point for the additions we are going to need to make (transponder etc)
Click to expand...

Really have me scratching my head on that one. But I'm sure that I have never wired a Cub as per the factory diagrams. To many improvements and to many changes since they were first drawn up. Not sure what your 'legal' situation is on that side of the pond but I've always just sat down and drawn up the diagram as needed.

Some things I always include are master and start relays with spike diodes. Wires sized as per tables in AC43.13. All switches and breakers moved to instrument panel. Separate main bus and avionics bus. DPST switch for master switch. It's actually a pretty simple layout for the airframe wiring.

Web
 
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