What was found
DURING A 100 HOUR INSPECTION, MECHANIC NOTICED CRACK IN THE WING SKIN IN MOST AFT OTBD SECTION OF LT WING. MECHANIC ALSO OBSERVED 2 RIVETS SHEARED THAT ATTACH THE OTBD AILERON HINGE BRACKET ASSY (CESSNA P/N 5021002-12) WHICH ARE SAME RIVETS THAT ATTACH THE TIP TANK SUPPORT BRACKETS (CESSNA P/N'S 0822600-29 AND -30 TO THE WING. THE MOST OTBD WING RIB WAS ALSO CRACKED IN THE MOST AFT LOWER SECTION (CESSNA P/N 0822040-17). TIP TANK STINGER (MOST AFT POINT) HAS SOME SLIGHT DAMAGE AS THOUGH IT STRUCK A SOLID OBJECT. AMOUNT OF WEIGHT WITH A FULL TANK OF FUEL BOUNCING ON THE TIP OF THE WING COULD ALSO BE A CONTRIBUTING FACTOR.