This a emai lI recieved with some adive I thought I would share.

Thanks for the photos.
>
> Sorry about your disaster with the '339. Your photo
> shows that the stab was
> not properly adhered to the fuselage, there is no
> glue adhesion on 75% of
> the gluing surface on the stab. But, the spar and
> the alignment pins were
> firmly anchored in the fuse (they were notched to
> give a good keying surface
> for glue), as designed. But, while this contributed
> to the stab departing
> the fuse, I do not think this is the initiating
> cause of the loss of the
> airplane.
>
> Both front and rear alignment pins were ripped out
> of the stab, and the
> aluminum spar was sheared. which tells me that there
> was severe
> back-and-forth rocking before failure - most likely
> from a flexing or
> dislodged elevator linkage causing stab surface
> flutter. The aerodynamic
> trim tab effect on the stab amplified the elevator
> motion to destruction.
> The front alignment pin is anchored in a balsa block
> the stab, and the whole
> block ripped out, as did the rear alignment pin
> (note elongated hole and
> ripped bottom skin).
>
> You may find your servo mounting dislodged, and
> linkage damage as well - of
> course, it's going to be hard to distinguish from
> damage after the crash.
>
> I do not think that making the alignment pin anchors
> any stronger would have
> saved your airplane, unfortunately - IMHO the root
> cause of the failure was
> elevator surface flutter, and you would have lost
> control anyway. A
> stronger joint *might* have delayed the stab's
> departure from the airplane
> and allowed you to slow down enough to stop flutter
> (if it was springiness
> in the linkage and not servo mount failure).
>
> I will be recommending to customers to roughen up
> the stab-fuselage
> interface with #200 sandpaper for a better keying
> surface and then wiping
> down with denatured alcohol before gluing to remove
> any traces of mold
> release, for better adhesion. The same should be
> done on all servo mounts
> adhered to the inside of the fuse.
>
> In addition, extreme care should be taken to ensure
> a slop-free,
> mechanically "stiff" (i.e., non-springy) control
> linkage, to avoid exciting
> aerodynamic flutter in the elevator. I personally
> recommend 4-40 linkage
> hardware and a supported pushrod rather than a free
> floating pushrod, in
> case of a long pushrod run.
>
> Again, sorry for your loss, and thanks for the
> photos. Compliments on your
> very nice P-80 and the beautiful home in the
> background!
>
> As I am not on RCU, I would be indebted if you would
> post this message on
> the board for me. Thanks!
>
> Andy Low
> ElectroDynamics, Inc.
> Home of "No-Hassle" RC Products
> http://www.electrodynam.com