Any rigid line needs special cushioned clamps to hold it to the engine. Reference the oil supply line to the prop on the Lyc IO360 engines. The line is alum/ss/steel, the fittings on both ends must be steel (to alum case!) and the clamps are specifically called out. This line carries high pressure prop oil from the governor on the back case to the transfer collar on the front case. HOWEVER, the lyc's have different vibration charactistics than the 13B/20B's so who knows? Just keep an eye on those rigid lines, and use cushions wherever you can.
Marc Wiese
>
> From: "kevin lane" <n3773@comcast.net>
> Date: 2004/08/25 Wed PM 05:01:42 GMT
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] more myths questioned!
>
> MessageOK, without stirring up a hornets nest-- could I safely run a rigid oil line to the redrive and back if both ends were rigidly engine mounted?  I would make sure there are bends in it for flex and well supported.  I have rigid brake lines on my -6a, with a 360 degree loop at the end, although admittedly, had one end crack, but I believe that was from a combination of multiple removals and later learning that my hangar partner's flange tool was actually automotive, not aviation. I've had no problems on my Lycoming otherwise with rigid lines.  I know some guys run flex lines everywhere, which seems heavy and expensive.
> Kevin Lane  Portland, OR
> e-mail-> n3773@comcast.net
> web-> http://home.comcast.net/~n3773
> (browse w/ internet explorer)
>   ----- Original Message -----
>   From: paul
>   To: Rotary motors in aircraft
>   Sent: Wednesday, August 25, 2004 9:26 AM
>   Subject: [FlyRotary] Re: Sorry Rusty - no bind
>
>
>
>     ----- Original Message -----
>     From: Russell Duffy
>     To: Rotary motors in aircraft
>     Sent: Monday, August 23, 2004 9:31 PM
>     Subject: [FlyRotary] Re: Sorry Rusty - no bind
>
>
>     please don't take this as being critical, I'm just asking - is it true or not that engine fittings should be steel, not aluminum?  or is that just a myth? does aluminum fatigue faster than steel?  what do certified piston planes use?
>     Kevin Lane  Portland, OR
>      
>
>     This is sort of a controversial subject.  There is probably an official FAA rule, or at least rule of thumb about only using steel fittings when there's relative motion on the two ends of a hose.  Of course screwing steel fittings, into an aluminum gear drive would also violate some dissimilar metal rules, so damned if you do, damned if you don't.  
>
>     Since I was schooled at the Van's Aircraft institute, I follow the more common sense rules.  If it's a small fitting, that isn't very strong, it's best to use steel.  If it's a fairly large fitting, then aluminum is plenty strong.  AN-6 is about the dividing line, and it comes down to whether there's much motion.  In the case of the drain fitting you see in the pic, there's no relative motion, so I feel aluminum is fine.  
>
>     Cheers,
>     Rusty (not an A&P, and don't even play one on TV)  
>
>     This topic was recently discussed on the canard aviator's website....seems that Lycoming is sending their brand new engines with aluminum fittings.  I agree, however that there is comfort in using steel for the smaller (-4) sizes.  I have -16 aluminum AN fittings for my radiator hoses, and it would take a sledgehammer to damage one of those aluminum fittings. The general consensus on the canard site was similar....steel for the smaller fittings, but aluminum was fine for -6 sizes and larger.  I guess they figure that if Lycoming can supply a certified engine with aluminum fittings, it's OK on our experimentals.  FWIW.  Paul Conner
>