 Depression after Washing
On Jul 6, 4:45 am, Dan_Thomas_nos...@yahoo.com wrote:
> On Jul 4, 4:56 pm, "Mike" <nos...@microsoft.com> wrote:
>
> > > Obviously, you haven't seen some of the things I have seen. One of the
> > > more tender, and more invisible spots on some airframes is where the
> > > horizontal stabilizer connects to the fuze. Many designs allow a
> > > tremendous moment arm for any non-balanced load on the stabilizer to
> > > stress the attachment points. This shows up as cracked spars on Cessnas,
> > > and I have seen stressed and cracked fittings from another airframe. How
> > > can this happen? Well on Cessnas it happens from folks using improper
> > > procedures to back the plane into a parking spot. It can also happen from
> > > innocent (but ignorant) bystanders, mowers, animal activity, or any of
> > > thousands of other posibilities.
>
> > I always give each side a good heave up and down for this very reason, so
> > such can easily be checked on the preflight for impending failure.
>
> A good heave up and down on the end of the stab of a 172
> flexes the center of the forward spar, eventually cracking it. A
> gentle bit of push-pull is all that's needed, to see if there's
> unusual tip travel. I bet your spar is cracked now. Many are. Cessna
> calls for stopdrilling the crack unless it has reached the spar
> flange, in which case it has to be repaired. I once flew a 172 that I
> subsequently found had a broken spar, busted clear through both
> flanges so that the skin was all that was holding it.
Why did your push-pull test not detect it? I prefer to give a shake
and feel the nature of surface response.
Cheers
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