Okay what am I doing wrong?

pczar3 · #1 05-22-2011, 05:33 PM

After reducing about a 40 inch piece of stainless tubing from aircraft spruce into a single 10 inch piece that finally worked I decided to take on one of the fuel lines. I have... make that "had" a new expensive imperial bender from ACS and tried to make the first bend. A loud snap and some words not to be repeated here is all I could here ringing in my ears! I spoke to ACS because the bender is listed as okay for stainless but when I went to the Imperial site it is not listed for stainless

What do you folks use for bending tubing? The stainless is the 3/8 304 seamless with a .035 wall. Is this the wrong material for the FWF? If it is the correct stuff, what benders are you using? I already had the one break and those that look more suitable are much more expensive.
I was a mechanic for Chevy in my early years and never had trouble like this which leads me to my original question... what am I doing wrong?
Thanks,
Paul

flion · #2 05-22-2011, 05:51 PM

There should be NO tubing forward of the firewall (some exceptions are injection tubes or pushrod covers). Fluid lines should all be flexible. Aft of the firewall, it should be aluminum tube.

Wayne Gillispie · #3 05-22-2011, 06:56 PM

The only place I have ever used stainless and it was 1/4" was helicopter hydraulic servo lines. They have 3000 psi on them. I use Parker tubing benders, separate one for each size.

Walt · #4 05-22-2011, 07:15 PM

Quote:

Originally Posted by flion

There should be NO tubing forward of the firewall (some exceptions are injection tubes or pushrod covers). Fluid lines should all be flexible. Aft of the firewall, it should be aluminum tube.

If that was true then why does Lycoming provide a nice SS line for the prop governor

RV8R999 · #5 05-22-2011, 07:25 PM

no way! Only lines going from fixed connection points off the engine directly to the engine must be flexible because of vibration. Otherwise any other line can be tubing.

TS Flightlines · #6 05-22-2011, 09:28 PM

the bender that you broke? Ive got a 370 and a 470, and bend .035 & .049 stainless with no issues. What part of the bender broke??
Tom

flion · #7 05-22-2011, 10:37 PM

Quote:

Originally Posted by Walt

If that was true then why does Lycoming provide a nice SS line for the prop governor

I did say there were exceptions. However, my prop governor line is not stainless, it's flexible. So is the line from my fuel servo to the spider. And there are also primer lines and probably other examples. As RV8R999 said, lines off the engine to fixed locations must be flexible. I would also point you to the ongoing debate about the brake lines; many feel the tubing is too susceptible to cracking and replace them with flexible lines. I stand by my statement; the kit comes with aluminum tubing for fixed lines but flex lines are recommended FWF.

pczar3 · #8 05-23-2011, 06:34 AM

Quote:

Originally Posted by TS Flightlines

the bender that you broke? Ive got a 370 and a 470, and bend .035 & .049 stainless with no issues. What part of the bender broke??
Tom

Hi Tom, I just bought the 470 and the adjustable handle stops broke. I don't need to get into the flame war on tubing vs. flex. I used the stainless between the firewall bulkhead fitting and the gascolator, just like the Piper I fly. I just ran into a problem because the ACS site says the 470 will do stainless and the Imperial site does not have it listed in their product selector for stainless but the web page does! This was with the .035. 304 seamless.
Paul

TS Flightlines · #9 05-23-2011, 06:55 AM

no flame war Paul----just interested in how yours broke and mine hasnt.
Tom

Quote:

Originally Posted by pczar3

Hi Tom, I just bought the 470 and the adjustable handle stops broke. I don't need to get into the flame war on tubing vs. flex. I used the stainless between the firewall bulkhead fitting and the gascolator, just like the Piper I fly. I just ran into a problem because the ACS site says the 470 will do stainless and the Imperial site does not have it listed in their product selector for stainless but the web page does! This was with the .035. 304 seamless.
Paul

flion · #10 05-23-2011, 07:57 AM

Sorry, Paul, when you asked in the first post if you were using the right material, I took that as a more general question. I don't feel that anyone has flamed me and I hope no one feels I've flamed them. As for using stainless for fixed lines or how to bend them, I can't help you - I don't have experience with stainless lines other than the hand-bent lines from my FI spider. And despite my comments about flex lines forward the firewall, I don't see a problem with a hard line to the gascolator; it's worked in lots of production aircraft.