There are detailed log books for the props until June 2002 when all four props were removed for work related to A.D. 81-13-06 in Canada, this work needs to be satisfied at an interval not exceeding 18 months.  It has been recommended that the props are removed and overhauled before the engines are started.  Weald Aviation Ltd. have prepared a plan for the overhaul and satisfaction of A.D. 81-13-06 of all four propellers in their on-site facility.