The vertical fin on a C-150 is held on to the fuselage with a welded
steel bracket riveted into the aluminum structure. The welds are in
the corners where the stress is highest. The steel undergoes galvanic
corrosion when it is close to aluminum. These aircraft are being used
well beyond their original intended lifetime and this steel fitting was
cracked in the welds on the two 150s I'm familiar with. I thought it
was a recent AD or at least a recent service letter. They were
certainly not airworthy.

This should be checked at annual on any 150 since it is an area of
known service difficulty.

The 172s don't have this problem with the bracket as it is an aluminum
forging - not prone to corrosion.

It would be one thing to lose a rudder, but losing both the rudder and
vertical fin would be pretty exciting. It would be even worse if the
rudder cables kept the separated surfaces attached to the rest of the
airplane.