This Maintenance Tip relates to AD/VAT/10 Amdt 6 Landing Gear Attachment Bolts.
In the early days of the Airtourer there were some failures of the landing gear attachments. Victa's investigations included setting up a rig that simulated 1,000 landings. One of the points of failure was the attachment bolt that is the subject of the AD. There are two methods of compliance with the AD, firstly use of a special bolt as per AESL SB 031 which has a life of 350 hours or alternatively using a standard AN bolt with equivalent length and diameter. The Co-Op has a supply of the special bolts. They are more expensive than AN bolts but are manufactured to a much finer tolerance as well as having a waisted shank. If the AN bolts are used, caution is required to ensure that they do not become threadbound. This is where the unthreaded part of the shank fouls the thread on the wing attachment. Correct use of washers should avoid this damage. The special bolts have a waist on the shank to avoid this possibility.