COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes AD/CESSNA 170/9 Amdt 1 Main Undercarriage "U" Bolts 11/67 Applicability: All 172, F172, FR172 and 175 series fitted with "U" bolts P/N 0541153. Requirement: 1. Visual: Inspect the main undercarriage "U" bolts P/N 0541153 type in situ for cracks or other damage and check that the "U" bolt retaining nuts are torqued to the values specified in the Cessna Service Manual. 2. Magnetic Particle: Remove the main undercarriage "U" bolts P/N 0541153 type and inspect by the magnetic particle method for cracks particularly in the radius of bends and in the root of the threads. Compliance: Visual: At intervals not exceeding 100 hours time in service. Magnetic Particle: At intervals not exceeding 500 hours time in service.