Firewall Amphenol Connectors


 

Started my wiring diagrams and lists, over 40 wires coming thru the firewall alone which raised this question ... Any of you used Amphenol connectors at the firewall, for ease of taking off the engine and clean install?
If so, I am lost in the different types there are ... anyone can help with this? What type for signal and low voltage wires?

For reference, here is what the DarkAero guys did ... https://youtu.be/-_zEcFkdq6Y?t=508

HAPPY 4TH,

Robert
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Jay Scheevel
 

I use several Amphenol “type” of conectors to make my engine wiring fully disconnect-able at the firewall. Some of these connectors (AN quality) are pricey, but they allow me to disconnect everything at the firewall, and I have done this several times now with relative ease.

 

You can get creative. I made my own thermocouple connectors (EGT,CHT) for example. You will want to know that when connecting thermocouple wires at the firewall, you need to maintain the same thermocouple metal throughout the connector’s conductors (same metal as in the thermocouple wire on both sides of the firewall), if you change metals inside of the connector, the hot side connection and the cold side connection will NOT cancel out. After I hand built my thermocouple connectors, I found out that Amphenol makes TYPE J and TYPE K metal compatible connectors. After I looked up the price ($$$$--Jet A/C stuff), I realized I probably was stayed a little richer to build my own.  Another way to handle this if you do not want to use metal-matched connectors as your disconnect, you will want to make sure that connector is entirely away from the firewall, so it is a constant temperature. Does not have to any particular temperature, you just want the connector and the wires at the same temp on either side of the junction, so the dielectric will cancel. Read Bob Nuckols  book for details on why.

 

So, to sum up, I would suggest running EGT and CHT through their own connectors (for reasons stated above), running all of your low current/signal wiring through connector/connectors of your preference (coax or shielded wire is always a good idea for signal wires). Give your high current…starter connections their own dedicated post connectors and make sure heavy enough wire is used throughout (marine catalogs are a good place to find these firewall post connectors). Use a nice braided strap to get your engine back to ground the starter. Give your alternator its own specific wire connectors and passthrough’s of their own, and make sure wire gauge is appropriate for the alternator output. Put a slow burn fuse or breaker on the alternator output that will limit current consistent with the max alternator output.

 

My 2 cents worth.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Robert Schmid
Sent: Sunday, July 3, 2022 12:47 PM
To: main@Q-List.groups.io
Subject: [Q-List] Firewall Amphenol Connectors

 

Started my wiring diagrams and lists, over 40 wires coming thru the firewall alone which raised this question ... Any of you used Amphenol connectors at the firewall, for ease of taking off the engine and clean install?
If so, I am lost in the different types there are ... anyone can help with this? What type for signal and low voltage wires?

For reference, here is what the DarkAero guys did ... https://youtu.be/-_zEcFkdq6Y?t=508

HAPPY 4TH,

Robert
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Jay Scheevel
 

A couple other things. On a composite aircraft there is no grounding to the airframe. This is a good thing, in my opinion, since a lot of metal plane builders get caught with noisy electronics because they are grounding things all over the airframe. You want to run a dedicated ground wire to a specific ground point for every device. The avionics should all ground to a common ground block. I kept my avionics ground block for only avionics and my “miscellaneous electrics” use a different dedicated ground block.  Starter ground wire should “home-run” all the way back to the main battery solenoid. Long wires and minimum gauge wire will only mean you have less cranking voltage, so with respect to your starter cables, if you can keep your cable runs as short as possible and the gauge as heavy as possible, that makes for a strong reliable start.

 

That makes 4-cents

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Robert Schmid
Sent: Sunday, July 3, 2022 12:47 PM
To: main@Q-List.groups.io
Subject: [Q-List] Firewall Amphenol Connectors

 

Started my wiring diagrams and lists, over 40 wires coming thru the firewall alone which raised this question ... Any of you used Amphenol connectors at the firewall, for ease of taking off the engine and clean install?
If so, I am lost in the different types there are ... anyone can help with this? What type for signal and low voltage wires?

For reference, here is what the DarkAero guys did ... https://youtu.be/-_zEcFkdq6Y?t=508

HAPPY 4TH,

Robert
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


 

Thanks a lot Jay, very helpful especially around the alternator and higher voltage cables. Did you see this picture?



--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.


Anthony P
 

I went through this process last fall (for the 4th or 5th time in my life).  Fairly painful unless you like unwanted puzzles.

You can get the P/Ns from the catalogs and plug them in here: https://www.trustedparts.com/en  to get a list of retailers that actually have stock.  This was crucial as no single vendor had the parts to make even one side of the connector.

I also use DigiKey and Mouser heavily to cross check the compatibility of my choices and revise.

If you have an avionics shop with proven compatible parts on the shelf that they are familiar with, use them even if twice the cost of what you can find on the internet.

I was quite determined to get the correct crimp-style thermocouple pins and sockets, and was finally successful after about a week's worth of time and probably two calendar months.  https://www.electroenterprises.com

There are many series and lots of variation within the series, so do your homework.  (see comment about avionics shop)  There are many types of strain reliefs, back-shells, custom heath shrink boots, coatings, and exit angles for all of these. Special clocking is also something to keep an eye on. Some connector P/Ns come with back-end bits, and some don't.  Sometimes hard to get proof of what's actually included and secondary orders might be necessary.  

These people are used to dealing with defense and aviation manufacturers with large quantities.  You will be annoying to them, but just keep pushing.  Keep the fact that you only want quantity 1 or 2 until as late in the conversation as you can.  Don't tell them your application.


--
Q2 N86KL


Michael Dunning
 

You'll probably want to look through here while you're at it for your FWF control runs: http://www.doubleteeproducts.com/doubleteefirewallproducts/
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Richard Thomson
 

    Hi Rob,

    The RDAC for my MGL EFIS is designed to be mounted engine bay side of the firewall, so there is only the CAN BUS twin cable and power cables going rearward ( plus a few discretes).   

    All the EGTs and CHTs are kept within the bay. much cleaner install.

    Rich T.

On 03/07/2022 19:46, Robert Schmid wrote:
Started my wiring diagrams and lists, over 40 wires coming thru the firewall alone which raised this question ... Any of you used Amphenol connectors at the firewall, for ease of taking off the engine and clean install?
If so, I am lost in the different types there are ... anyone can help with this? What type for signal and low voltage wires?

For reference, here is what the DarkAero guys did ... https://youtu.be/-_zEcFkdq6Y?t=508

HAPPY 4TH,

Robert
--
Robert "TheFrisco" Schmid
(408) 805-5450

www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com

Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.