Don't rely on the L13 bulkhead. There is a SB out for material strength
on the bulkhead. Apparently some were manufactured using too soft a
material. If yours is affected then lateral loads are going to cause the
bulkhead to collapse.

We have had three failures in one year with bulkhead 14 deforming on the
L13. One was a ground loop, the others appear to be overstress from
landing on rough grass. Might be an idea to start using flaps on landing
(current procedure is to land with no flaps) - or maybe the summary is
to get our runway graded again...