The following text from Aviation Week is not unique to the aircraft
pictured:
05/16/1960. The H-43 was grounded May 9th because of limited clearance
between rotors and tail fins, which have been hit by blades.
06/06/60. The fix to this problem was to replace the top 10 in (2.39
m) of the tail with a light plastic material that will not damage
rotors if they strike it.
09/12/1960. Production models eliminate the middle tail and replace it
with two shorter vertical stabilizers on each side.