Caution - solid copper tubing from engine to firewall

[Janekom]

Just wondering about the use of a solid copper wire (edited - should read tubing/pipe - sorry) from the engine to the firewall.
Recently we have seen an RV7A here in South Africa ( imported used ) had a catastrophic engine failure with a con rod through the crankcase! The reason - there was a solid cooper pipe (1/8" I think ) between the engine and the firewall from where it was connected to the oil pressure gauge.

Yesterday I have helped someone on a used RV6A ( also imported ) and this baby had the same copper wire for the oil pressure as well as the fuel pressure.

I really thought this is not a good idea and these should be done with a braided SS flexible hose.

What does the experienced guys say about this?

[AltonD]

There is considerable movement of the engine on start and shutdown. Also, there is always vibration. The solid copper tubing will fatigue and fail. It work hardens very easily. SS braided hose is the way to go.

[pierre smith]

...should copper tubing be used on either the oil pressure or fuel sender lines!

Pardon the pun but this is playing with fire!

Best,

[kevinh]

Speaking of this: I used the 1/8" copper tube for the primer lines (per van's suggestion and some certified planes). Should I periodically take it off and anneal it?

[JonJay]

Originally Posted by kevinh

Speaking of this: I used the 1/8" copper tube for the primer lines (per van's suggestion and some certified planes). Should I periodically take it off and anneal it?

As long as it is installed correctly with a few "loops" in the line between the engine and the firewall, normal inspection for cracks should be all you need.

[az_gila]

Originally Posted by kevinh

Speaking of this: I used the 1/8" copper tube for the primer lines (per van's suggestion and some certified planes). Should I periodically take it off and anneal it?

...the original poster mistook a 1/8 copper pressure line (instruments or primer) that is 1/8 tubing for a solid copper connection?

[Bavafa]

IMHO, it is the quickest way to get yourself into trouble, correction, big trouble.

[trib]

The 1/8" copper tubing isn't just Van's method, this is the standard engine installation method. When I installed mine, I put in 2 sets of two loops, at right angles to each other. Probably overkill but I wanted plenty of tubing to allow for vibration. The difference between the primer and oil pressure in the application of the copper tubing is that the primer is pressurized with fuel only when you are actually priming the engine, which you wouldn't be doing in flight, whereas the oil pressure would always be pressurized when the engine is running. While a failure would not be a good thing, you can see the difference.

[Neal@F14]

Solid copper lines are appropriate for plumbing a toilet, not an airplane.

But having said that, my 44 yr old Cherokee has solid copper lines for the oil pressure and fuel pressure guages... from the factory. But there is a section of flex hose in each one that connects to fittings on the engine to handle vibration.

PS: No jokes about a Cherokee being a flying toilet, please.

[Radomir]

Why would you build an RV-7A like that? Plans specifically call out for a flex hose for oil pressure (and fuel pressure too).

Had the pre-buy been done on this airplane?