On Thu, 30 Apr 2009 15:18:38 -0700 (PDT), Oliver Arend
wrote:

It is the wing struts.

Taken from:http://rgl.faa.gov/Regulatory_and_Gu...visoryCircular...

23.369 Rear lift truss (Amendment 23-48

[...]“Wing struts” are usually loaded in tension (for positive load factor conditions)—except during negative “g” maneuvers or gusts, inverted flight conditions (aerobatic maneuvers), landing, and taxi. In these latter cases, the struts can be loaded in compression; therefore, they are subject to Euler column buckling phenomena. Even when on the ground, the airplane rear lift truss (or strut) can experience significant compression loads if the airplane has a tail wheel. This is especially true when the airplane is tied down or is taxiing downwind.

So from what I understand the wing strut (as on most Cessna SEP, like
http://www.fly365.co.uk/images/cessna152-gbhwa.jpg) may under certain
circumstances be subjected to a higher compression load if the plane
is oriented away from the wind (especially with a tailwheel - higher
AOA) than it would be within the regular V-n flight envelope?

we get accustomed to thinking about aerofoils blunt end forward.
sharp end forward still works to generate lift but with less
efficiency.

just mentally stand on your head and look at the wing in a tailwind.
it is sitting there in the breeze at a few degrees angle of attack,
and it will generate lift compressing the strut.
a taildragger sits with much more angle of attack (remember we're
upside down) and will generate more lift force.

back up the right way now...
generally the rear strut of the two is a smaller section than the
front strut and is more subject to buckling failure than the leading
strut. this is just a calculation verifying that there isnt a problem.