What was found
DURING THE NORMAL INSPECTION INTERVAL, CRACKS WERE FOUND IN THE WING RIBS WHERE THE INBOARD AILERON HINGE PLATES (PN 105-100011-51) AND THE OUTBOARD AILERON HINGE PLATES (P/N 105-100011-51) ATTACH. THE SAME PROBLEM HAS BEEN FOUND ON OTHER AIRCRAFT OF SAME MODEL. REPAIRS WERE MADE BY FABRICATING A DOUBLER FOR EACH RIB. ON A PREVIOUS AIRCRAFT, ALL FOUR RIBS WERE REPAIRED WITH DOUBLERS EVEN THOUGH ONLY THREE WERE DETERMINED TO BE CRACKED. THE UNCRACKED RIB NEVER CRACKED WITH THE DOUBLER INSTALLED.