Ed,
Van used to recommend only steel AN fittings on the lycomings until it was
pointed out that the brand new engines were shipped from the factory with some
flight critical aluminum at which time Van backed away from his recommendation.
Did the DIE variable length fly yet?
Bernie
----- Original Message -----
Sent: Thursday, March 04, 2004 4:00
PM
Subject: [FlyRotary] Re: Aluminum AN
fittings - Safety (was Re: [FlyRotary] Re: ready to start?
----- Original Message -----
From: "David Carter"
<dcarter@datarecall.net>
To:
"Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent:
Thursday, March 04, 2004 12:26 PM
Subject: [FlyRotary] Aluminum AN fittings
- Safety (was Re: [FlyRotary] Re:
ready to start?
>
Paul,
>
> You mentioned "aluminum 1/4 NPT to -6AN adapter".
It is my understanding
> that there is a real risk in using aluminum
fittings on engines due to
lack
> of "fatigue life" robustness of
aluminum, compared to steel AN fittings.
> There have been cases of
these aluminum fittings eventually breaking off
> where they are
threaded into the engine block.
>
> It is my understanding, from
reading the "lists" and articles in Kitplanes
&
> Sport Aviation,
that steel fittings are preferred over aluminum - that
> aluminum can
actually be considered a safety hazard.
>
> David
I suspect
that in case of an engine with lots of vibration such as an
Lycoming that
steel AN fittings are a prudent option. Most folks I know
flying
rotaries use Aluminum fittings and as yet, I have not hear of
one
failing. But then that might be because only Tracy has any
considerable
number of hours yet. In some cases - like fittings to
radiators - there is
little choice but to use aluminum
fittings. Something to keep our ears open
to anyone who has had bad
experience with aluminum fittings. Needless to
say any fitting
whether steel or aluminum should have minimum stress from
hose/tubing
attached to the fitting.
Ed Anderson
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