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Tail NAV Light Electrical Issue: One Step Forward, Two Steps Back


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Hi all,

Note/Edit: After seeing @carusoam's post below, I just wanted to clarify that we are working with an A&P on this project and so we need everything done up to a quality that he will sign off on...

We are the (two) new owners of a 1969 M20F (N9150V) which we bought in December from @Stephen after we found his posting here on Mooney Space and after @Culver LFA ferried it from MO to Oakland, CA. Its a nice flying machine, but like anything that age it has a few things we need to deal with. Right now we are working on a tail nav/strobe replacement and could use a little advice both on resolving the initial problem and then the problem we created when started "fixing" things.

Issue 1: Tail NAV light is out, plastic is damaged. Initial diagnosis: Light assembly is old, maybe has water damage and has failed. Solution: Replace it with a Whelen Orion 500v. Result: Strobe works, NAV light still not working.

Debugging1: The voltage on the strobe is ~12v and the NAV light works on this as expected. The voltage on the NAV circuit is sometimes 9.5 or maybe 11.5 or maybe 8, but always varying moment to moment. When connecting the NAV light to the NAV circuit the votage drops from whatever voltage it was showing down to 1 or 1.5v.

Analysis: OK so we should have done this test before buying a replacement light(!). I looked at the filament in the incandescent bulb and verified it was not broken and so I *assumed* that the internal electronics had failed and did not consider or fully test the circuit itself.

Debugging2: So initial troubleshooting shortcomings aside, we were able to determine that something was going on on the positive side of the circuit and and started to dig into the NAV light schematics in the maintenance manual (page 9-81 image below) to start breaking it down into bite size chunks. We already had verified that there was no continuity and extremely high resistance from the NAV light switch to the tail. So the first chunk was to test from the tail to the first connection (#1 in "Schematic LN-1" screenshot below) where we verified continuity and measured very low resistance. We noted a little bit of corrosion in the pins (#5 in photo below) and sprayed it with electrical connector cleaner and wiped the mail connectors as best we could. So first section was tested good, from the plug (male) connectors to the tail cone...

image.thumb.png.0b75020886406fbf852cc6b5c6ea819d.png

 

Then umm... wait a minute, why is that dangling wire there? Wait, why is the master switch no longer turning the power on? OK, we can no longer work on issue #1 because we need to address the problem we just created which is...

Issue2: Total electrical  power loss/master switch no longer turns on power.  

Analysis: Dangling wire labeled "20PB10A18" (#3 in schematic below, #6 in photo below)) was connected to "N" hole in receptacle (#2 in schematic PB-1 below) became brittle and broke off when we disconnected (and wiggled and moved around) plug 20-PB09B (#5 in first photo below) from receptacle 20-PB08B (#4 in 1st photo below).

image.thumb.png.65cb1d658f2e1a0aeaf7df746f6e71a2.png

 

image.thumb.png.0af36357a1a584971ff13a2152f3b49a.png

 

(Would be) Resolution: Remove pin with jury rigged extractor and replace it with um, a thing um size um... and this is where we get stuck...

image.png.5eaf49ac27132ab3880abfe2a6b43a10.png

Questions related to issue #2:

What size pin is this and where does one go to find a replacement? I am sure if I had the size I could find it, but a supplier name could be helpful. Also, these were crimped rather than soldered which surprised me- thoughts on the replacement? If the wire seems to be too brittle over more than just the last quarter inch when we strip it back, should we consider replacing the length? If so what is appropriate wire/part number for that? How do we go about labeling it for posterity?

Now that that is settled and power will soon be restored we can get back to the original issue...

Meandering Thoughts and Questions related to issue #1:

Having isolated and confirmed continuity downstream of the plug, the problem is either the contacts within the plug/receptacle assembly of upstream to the switch. Left and right NAV/strobes are fine and both go through that connection. Access to the second "flight panel" plug/receptacle (Schematic 1-  20LP06A/20LP07A respectively) is pretty onerous. In fact, while I can see up into the rats nest of wires behind the panel that there are a couple of candidate connectors, it is unclear which is which and how one would go about disconnecting them- there just is not any real access or good visibility. Maybe I am looking in the wrong place. To bypass access issues and having to dig the hole we are in even deeper, would it be a legal approach to go straight from the NAV switch, which is accessible, and put in a new wire that goes directly from there to the receptacle side of #1 in the upper schematic- in other words when re-wiring something does it need to be replace a like with a like? And regardless of legality, would it be unwise to that? I can't see anything about that that would be unsafe and that would make it a much more painless speedy fix. And are there better (AMP?) connectors that the black plastic ones- should we consider replacing the assembly now that we have it out- that seems like if might be more trouble than its worth, but would not want to waste the opportunity if it should be done...

One step forward, two steps back...

Any advice on how to proceed?

Johnny

 

 

 

 

 

Edited by johnnyu
Clarification of A&P involvement
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Advisory Circular AC No: 43.13-1B ACCEPTABLE METHODS, TECHNIQUES, AND PRACTICES - AIRCRAFT INSPECTION AND REPAIR is the reference I would use for your legal question. A&P will want some reference to substantiate the repair. I think you will be able to extract the old pin, install new and repair the connector. I also think you could abandon the pin, leave the connector in place for the remaining wires and bypass for your broken wire. Use 2 aviation butt splices, a piece of aviation electrical wire of same AWG  and an aviation connector. Same result, same functionality, approved components at the same location. As long as A&P approves of repair it seems this would be easier and you won't break the rest of the wires in the process.

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Aircraft connections are crimped, not soldered. Crimp connections (properly done) hold up better under vibration. Solder can wick up the wire and form a weak spot where the solder ends. Make sure you use the correct crimp tool for the pins. Warning: quality crimp tools can be scary expensive. 

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3 hours ago, PT20J said:

Aircraft connections are crimped, not soldered. Crimp connections (properly done) hold up better under vibration. Solder can wick up the wire and form a weak spot where the solder ends. Make sure you use the correct crimp tool for the pins. Warning: quality crimp tools can be scary expensive. 

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That is really good to know!

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31 minutes ago, M Terry said:

Is the AWG of the wire indicated by the part number?

that wire to the battery is 20PB10A18, in fact all the wires on that page start with 20 and end with 18. are the 20AWG, or 18AWG?

I believe that the wire code is AABBCCDEE

AA = model/serial number range

BB = Circuit function [PB = Power - Battery (output and control)]

CC = Wire sequence

D = Configuration

EE = Wire size

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You will find things soldered on your aircraft, usually it’s supplied components that come that way.

Many want to believe that a soldered and heat shrunk joint is the best, but they woud be incorrect, it’s vibration thst causes the wire to break right at the end of the solder as the solder has no give, a crimped joint will hold up better.

‘I’m not aware of Aviation specific butt splices, at the factory I worked at they had used for years regular just crimp splices, I had then change to Ancor brand butt splices and terminals as they use hot glue lined shrink wrap. so you crimp the terminal just like normal. but then hit it with a heat gun, this both shrinks the plastic tight, but also melts the hot glue which forms an airtight seal, but also adds an adhesive bond thst helps keep the crimp from being pulled on.

‘In my opinion they are vastly superior, but be careful as there are a lot of Chinese knock offs that are much lower quality, be sure to only get Ancor brand, Amazon, Home a depot, Lowe’s and also most Marine stores as it’s primary target is boats as it’s a waterproof and therefore a corrosion proof connection.

‘If you do much wiring, you want good ratcheting crimpers and a good one may be the second most expensive tool in your box, depending on what you have in there

Edited by A64Pilot
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14 hours ago, johnnyu said:

Hi all,

We are the (two) new owners of a 1969 M20F (N9150V) which we bought in December from @Stephen after we found his posting here on Mooney Space and after @Culver LFA ferried it from MO to Oakland, CA. Its a nice flying machine, but like anything that age it has a few things we need to deal with. Right now we are working on a tail nav/strobe replacement and could use a little advice both on resolving the initial problem and then the problem we created when started "fixing" things.

Issue 1: Tail NAV light is out, plastic is damaged. Initial diagnosis: Light assembly is old, maybe has water damage and has failed. Solution: Replace it with a Whelen Orion 500v. Result: Strobe works, NAV light still not working.

Debugging1: The voltage on the strobe is ~12v and the NAV light works on this as expected. The voltage on the NAV circuit is sometimes 9.5 or maybe 11.5 or maybe 8, but always varying moment to moment. When connecting the NAV light to the NAV circuit the votage drops from whatever voltage it was showing down to 1 or 1.5v.

Analysis: OK so we should have done this test before buying a replacement light(!). I looked at the filament in the incandescent bulb and verified it was not broken and so I *assumed* that the internal electronics had failed and did not consider or fully test the circuit itself.

Debugging2: So initial troubleshooting shortcomings aside, we were able to determine that something was going on on the positive side of the circuit and and started to dig into the NAV light schematics in the maintenance manual (page 9-81 image below) to start breaking it down into bite size chunks. We already had verified that there was no continuity and extremely high resistance from the NAV light switch to the tail. So the first chunk was to test from the tail to the first connection (#1 in "Schematic LN-1" screenshot below) where we verified continuity and measured very low resistance. We noted a little bit of corrosion in the pins (#5 in photo below) and sprayed it with electrical connector cleaner and wiped the mail connectors as best we could. So first section was tested good, from the plug (male) connectors to the tail cone...

image.thumb.png.0b75020886406fbf852cc6b5c6ea819d.png

 

Then umm... wait a minute, why is that dangling wire there? Wait, why is the master switch no longer turning the power on? OK, we can no longer work on issue #1 because we need to address the problem we just created which is...

Issue2: Total electrical  power loss/master switch no longer turns on power.  

Analysis: Dangling wire labeled "20PB10A18" (#3 in schematic below, #6 in photo below)) was connected to "N" hole in receptacle (#2 in schematic PB-1 below) became brittle and broke off when we disconnected (and wiggled and moved around) plug 20-PB09B (#5 in first photo below) from receptacle 20-PB08B (#4 in 1st photo below).

image.thumb.png.65cb1d658f2e1a0aeaf7df746f6e71a2.png

 

image.thumb.png.0af36357a1a584971ff13a2152f3b49a.png

 

(Would be) Resolution: Remove pin with jury rigged extractor and replace it with um, a thing um size um... and this is where we get stuck...

image.png.5eaf49ac27132ab3880abfe2a6b43a10.png

Questions related to issue #2:

What size pin is this and where does one go to find a replacement? I am sure if I had the size I could find it, but a supplier name could be helpful. Also, these were crimped rather than soldered which surprised me- thoughts on the replacement? If the wire seems to be too brittle over more than just the last quarter inch when we strip it back, should we consider replacing the length? If so what is appropriate wire/part number for that? How do we go about labeling it for posterity?

Now that that is settled and power will soon be restored we can get back to the original issue...

Meandering Thoughts and Questions related to issue #1:

Having isolated and confirmed continuity downstream of the plug, the problem is either the contacts within the plug/receptacle assembly of upstream to the switch. Left and right NAV/strobes are fine and both go through that connection. Access to the second "flight panel" plug/receptacle (Schematic 1-  20LP06A/20LP07A respectively) is pretty onerous. In fact, while I can see up into the rats nest of wires behind the panel that there are a couple of candidate connectors, it is unclear which is which and how one would go about disconnecting them- there just is not any real access or good visibility. Maybe I am looking in the wrong place. To bypass access issues and having to dig the hole we are in even deeper, would it be a legal approach to go straight from the NAV switch, which is accessible, and put in a new wire that goes directly from there to the receptacle side of #1 in the upper schematic- in other words when re-wiring something does it need to be replace a like with a like? And regardless of legality, would it be unwise to that? I can't see anything about that that would be unsafe and that would make it a much more painless speedy fix. And are there better (AMP?) connectors that the black plastic ones- should we consider replacing the assembly now that we have it out- that seems like if might be more trouble than its worth, but would not want to waste the opportunity if it should be done...

One step forward, two steps back...

Any advice on how to proceed?

Johnny

 

 

 

 

 

I may have some pieces of 18 ga wire, with that pin crimped on it left over from my avionics upgrade. I will be out at the hangar  tomorrow, I will check. If I do I will send it to you and you can splice the wire down stream of the connector.

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Welcome aboard to the first post people..!  :)

 

Some tidying up to be covered...

MS has some pretty talented people... some talented people have joined today...

 

When doing PM on your certified planes... speak openly when following the rules...

example of the PM rule for private pilots...

https://www.boldmethod.com/learn-to-fly/regulations/your-guide-to-preventative-maintenance-what-you-can-fix/

 

Often... as PPs we neglect to mention we are working with our mechanic...  or are a mechanic...  or logging the work properly...

 

It helps the image of MS... when references are tossed in...

I’m getting data for my mechanic...

My mechanic is signing this off in the logs...

 

Add a few extra words that show you are familiar with the rules every now and then...

 

This will help somebody less fortunate from thinking...   “everyone else is doing this... why can’t I?”

 

PP thoughts only, not a mechanic... or web master...

 

Best regards,

-a-

 

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20 hours ago, carusoam said:

Welcome aboard to the first post people..!  :)

 

Some tidying up to be covered...

MS has some pretty talented people... some talented people have joined today...

 

When doing PM on your certified planes... speak openly when following the rules...

example of the PM rule for private pilots...

https://www.boldmethod.com/learn-to-fly/regulations/your-guide-to-preventative-maintenance-what-you-can-fix/

 

Often... as PPs we neglect to mention we are working with our mechanic...  or are a mechanic...  or logging the work properly...

 

It helps the image of MS... when references are tossed in...

I’m getting data for my mechanic...

My mechanic is signing this off in the logs...

 

Add a few extra words that show you are familiar with the rules every now and then...

 

This will help somebody less fortunate from thinking...   “everyone else is doing this... why can’t I?”

 

PP thoughts only, not a mechanic... or web master...

 

Best regards,

-a-

 

We are definitely working with our mechanic, with his advice, inspection, and sign off of each aspect of the work.

found a supplier for the pins: https://www.newark.com/

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50 minutes ago, johnnyu said:

Does anyone have a recommendation on a crimper that they are happy with in terms of quality? You can find some really cheap ones on Amazon and you can also go to TE and find some that are $500+.

I think the 8 pin avionics crimpers would work if you set the crimp correctly. You would probably have to hold the pin in the correct position.

https://www.ebay.com/itm/251195694843?chn=ps&mkevt=1&mkcid=28

 

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2 hours ago, johnnyu said:

Does anyone have a recommendation on a crimper that they are happy with in terms of quality? You can find some really cheap ones on Amazon and you can also go to TE and find some that are $500+.

The DMC tools are the good ones, but they're expensive and used ones are hard to find, and you need to make sure it's either the right one for what you need or has the proper barrel(s) for you application(s).  They are really good for the job, though.

I've never used one but the Stein Air tool seems to be a go-to for some occasional users:

https://www.steinair.com/product/4-way-indent-crimper/

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6 hours ago, EricJ said:

The DMC tools are the good ones, but they're expensive and used ones are hard to find, and you need to make sure it's either the right one for what you need or has the proper barrel(s) for you application(s).  They are really good for the job, though.

I've never used one but the Stein Air tool seems to be a go-to for some occasional users:

https://www.steinair.com/product/4-way-indent-crimper/

That one only goes to 20 gauge terminals. The one I referenced above does 18 gauge terminals.

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56 minutes ago, N201MKTurbo said:

That one only goes to 20 gauge terminals. The one I referenced above does 18 gauge terminals.

Thanks for pointing that out.

 

2 hours ago, N201MKTurbo said:

That one only goes to 20 gauge terminals. The one I referenced above does 18 gauge terminals.

@N201MKTurbo- The P/N for the plug side of the connector is 201298-1 which takes AMP Type II connectors. Its unclear to me if the crimper you noted above will do that- it lists Deutsch-style connectors. And tools that look analogous also mention Deutsch and Amphenol connectors interchangeably. Is AMP II an equivalent?

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2 minutes ago, johnnyu said:

Thanks for pointing that out.

 

@N201MKTurbo- The P/N for the plug side of the connector is 201298-1 which takes AMP Type II connectors. Its unclear to me if the crimper you noted above will do that- it lists Deutsch-style connectors. And tools that look analogous also mention Deutsch and Amphenol connectors interchangeably. Is AMP II an equivalent?

I don’t know for sure. But there is a good likelihood it will work. The 4 or 8 pin crispers have adjustments for how far they crimp. The other function of the crimper is to hold the pin in the center of the pins at the correct height. If the crimper won’t hold it at the correct height, you can just hold the pin and wire in the correct position while you actuate the crimper. It is a bit harder, but not that hard. After all you only need to crimp one pin.

I would get a few extra pins to practice with.

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8 hours ago, johnnyu said:

Thanks for pointing that out.

 

@N201MKTurbo- The P/N for the plug side of the connector is 201298-1 which takes AMP Type II connectors. Its unclear to me if the crimper you noted above will do that- it lists Deutsch-style connectors. And tools that look analogous also mention Deutsch and Amphenol connectors interchangeably. Is AMP II an equivalent?

I don't believe that the crimper that @N201MKTurbo references crimps the 164164-1 pins that fit the connector you referenced. The crimper you need for those pins is something like the Molex 0638190901 that DigiKey sells. I have a much cheaper version that is non-ratcheting that I have had for a long time. I can't find a reference to it but it cost about $40.00 dollars. The Molex 0638111000 looks like it will work although I wouldn't want to do a lot of pins with it. If you zoom in to either picture of the Molex crimpers you can see that the crimp is designed to roll the flat metal over to capture the wire and insulation.

If you are anywhere near Huntsville, AL I will be happy to crimp the pins for you or lend you my crimper.

Jim

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3 minutes ago, jcovington said:

I don't believe that the crimper that @N201MKTurbo references crimps the 164164-1 pins that fit the connector you referenced. The crimper you need for those pins is something like the Molex 0638190901 that DigiKey sells. I have a much cheaper version that is non-ratcheting that I have had for a long time. I can't find a reference to it but it cost about $40.00 dollars. The Molex 0638111000 looks like it will work although I wouldn't want to do a lot of pins with it. If you zoom in to either picture of the Molex crimpers you can see that the crimp is designed to roll the flat metal over to capture the wire and insulation.

If you are anywhere near Huntsville, AL I will be happy to crimp the pins for you or lend you my crimper.

Jim

The crimper you show will work with the type 3 pins the type 2 pins need the 4 jaw crimper.

image.png.49360a69282504d21248fc225647e083.png

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3 minutes ago, N201MKTurbo said:

The crimper you show will work with the type 3 pins the type 2 pins need the 4 jaw crimper.

image.png.49360a69282504d21248fc225647e083.png

Interesting. When I look up that connector on the Newark website it shows a 164164-1 pin which fits the crimper I referenced. The one you referenced certainly fits the pin that you show. I wonder if there are multiple pins that fit that connector. Probably need to make sure to order the crimper and pin as a matched set.

Jim

Edited by jcovington
Change website to Newark.
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Just now, jcovington said:

Interesting. When I look up that connector on the Digikey website it shows a 164164-1 pin which fits the crimper I referenced. The one you referenced certainly fits the pin that you show. I wonder if there are multiple pins that fit that connector. Probably need to make sure to order the crimper and pin as a matched set.

Jim

The OP said they were going to use AMP Type II pins. Which looks like what was in there before. They are the best.

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Just now, N201MKTurbo said:

The OP said they were going to use AMP Type II pins. Which looks like what was in there before. They are the best.

Agree. The Type II pins are better and it does appear to be what he removed from the connector. I followed the reference he gave to the Newark site. My concern was that he would buy the Newark referenced pins and have the incorrect crimper.

Jim

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We’ve ordered the Amp type II parts and a crimping tool similar to the above that handles the Deutsch style solid barrel pin. I’ll report back on if it is compatible and creates a quality crimp. Looking at the CAD drawings of both types shows that they are close in dimension but not the same.

Johnny

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