COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Embraer EMB-120 (Brasilia) Series Aeroplanes AD/EMB-120/24 Aileron Mass Balance Weights 5/98 Applicability: All models EMB-120 aircraft. Requirement: Inspect in accordance with Embraer Service Bulletin 120-27-0077 Revision 01. Note: CTA AD 98-01-02 Amdt 39-826 refers. Compliance: For Part I of the Requirement Document: Within 150 hours time in service after 23 April 1998, and thereafter at intervals not to exceed 1,000 hours time in service until accomplishment of the inspection required by Part II of the Requirement Document. For Part II of the Requirement Document: Within 2,000 hours time in service after 23 April 1998 or one calendar year, which ever occurs first. This Airworthiness Directive becomes effective on 23 April 1998. Background: Investigation has revealed the possibility of a deformation occurring in the mass- balance weights of the aileron, which could eventually lead to a physical contact and possibly friction between the exposed end of the mass-balance weight with the adjoining attach fitting.