COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell UH-1 Series Helicopters AD/UH-1/2 Tail Rotor Slider 4/97 DM Applicability: All models. Requirement: Measure the outside diameter of the splined shaft (barrel) of the slider Part Number 204-010-720-3, or Part Number 204-010-720-003 at two points that are 90 apart on the outside circumference, at ½" to 1" from either end of the slider. Replace any slider which measures less than 1.300". Note: FAA AD 97-01-06 refers. Compliance: Within 5 hours time in service after 12 February 1997. Background: US Army "Breakout" spares of this item have been discovered with less than the minimum wall thickness. This Directive is to prevent a possible fatigue failure of a defective slider which would result in the loss of the tail rotor.