| flion |
08-07-2016 08:37 AM |
Quote:
Originally Posted by steve murray
(Post 1101194)
Sorry, can you educate me on what a sealed "CPC" is? I am probably 1 year + from working on firewall but trying to learn.
Thx
Steve
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Try here: http://www.omega.com/pptst/MTC_CONN.html. Actually, CPC is a bit of a misnomer because they are not plastic; they have aluminum bodies and a bundle shell (about 3" long) that serve to protect the connection from flame and heat. The pins themselves are bedded in a flexible synthetic material that is supposed to be fluid-resistant.
Understand that they are not flame-proof. But they are way better than Circular Plastic Connectors and probably as good as many of the other pass-throughs in common use, where the weak link is burn through of the wire insulation being passed. The idea of such devices (shields and such) is to minimize the exposure and grant a little extra time (seconds?) to deal with a fire incident.
So why not just use one of the simpler and much less expensive solutions available? When I had my landing incident in my RV-6A, I had to replace the fire-wall and a couple of the stringers behind it. This meant that I had to undo connections to thermocouples and sensors, etc. and thread them all back through the firewall. The worst were the connectors for the Lightspeed ignitions, 25-pin soldered connectors on the cold side to the crank sensor circuit board (potted connections) on the hot side. It took some large penetrations and creative shielding but I managed it. I also decided that the automotive approach of a connector at pass through was the way to go. In the -10, if I need to remove the engine, I won't have to decouple each individual CHT, EGT, etc. Instead, I will just have to undo the starter cable, grounding strap, and two bundle connectors (not mentioning fuel and oil lines). If (gods forbid) I have an incident similar to the one I had before, replacing the firewall won't involve a lot of wiring work. And I carried the idea through the plane. Replace a rudder? Just wire the rear strobe and trim servo to a CPC in the bottom fairing and attach to the connector already routed from the fuselage.
The downside of connectors is connector reliability and maintenance (plus initial expense). But you can select good quality connectors with some research and maintenance is not difficult during inspection. Consider the reliability of the connectors already in use in lighting systems, for example. But, as with everything else in experimental aviation, it is individual choice and preference.
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