C wrote:
Working on a 100hour just a month before the annual is due -- my
mechanic and I lifted the back seat to look at the cabling underneath.
Lo and behold -- we found a "tear" in an aluminum bulkhead under the
back seat.

The bulkhead is under the back of the rear seat and doesn't appear to
be structural as it is thin aluminum. But there is a steel brace
coming in from the flap area of the wing and rivited to the lower
outside corner of the aluminum bulkhead.

I'd be carefull jumping to the conclusion that's it isn't structural.
That steel plate is the rear wing attach fitting. And I believe the
bulkhead that it's attached to is considered the "rear spar carry through"
(like a "mini" spar). Cherokee's have a large center spar, but also have
a front and rear attach point and carry through. The front carry through
is behind where your heels sit when you're in the pilot's seat (under the
plastic trim pieces). The rear one is where you describe.


However on mine, just next to the steel brace on the baggage door side
-- there is a inch long tear up from the bottom of the bulkhead and a
small buckle in the aluminum brace above the tear. Its like there was
a terrific upwards stress on the bottom corner of the bulkhead where
the steel is rivited and it tore the aluminum bulkhead upwards.

There was a person on the Cherokee Chat (see Jay Honeck's post) a few
weeks ago that had very similar crack and he posted pictures. I hope this
isn't the beginning of a trend, or we'll be seeing an AD soon.

You're correct in assuming a "terrific upward stress", although I would
have hoped that a hard landing or bad turbulence wouldn't have caused such
damage. You'll want to make sure you have a very competant mechanic fix
this. Wing departure, or severe twist, while in flight would really suck.
You might want to show this to your local FSDO, too. I hate to encourage
and AD, but this could be a problem we might not want to ignore.

--- Jay


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