COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Gulfstream (Grumman) G1159 and G-IV Series Aeroplanes AD/G1159/37 Wing Plank Splice Between BL 135 and BL 156 9/94 Applicability: All model GII, GIIB and GIII aircraft. Requirement: Inspect the wing plank splice fail-safe channels and splice fittings on the lower middle and aft wing plank splices between BL 135 and BL 156, to detect cracks, in accordance with Gulfstream Customer Bulletin (GCB) 400A for GII aircraft, GCB 403A for GIIB aircraft, or GCB 114A for GIII aircraft. Note: FAA AD 93-01-18 refers. Compliance: Unless previously accomplished, inspect within 150 flight hours or 90 days from 18 August 1994, whichever occurs first. For those aircraft found to have cracks which are within the limits and conditions specified by the applicable GCB, re-inspect at intervals not to exceed 6 months, until repaired or replaced. Repair or replacement must be completed no later than the next regularly scheduled 18-month wing tank interior inspection. Thereafter, inspect in accordance with the Maintenance Manual requirements for this area. Background: This AD is prompted by reports of cracks in the fail safe channels and splice fittings of several GII and GIII aircraft, which extend beyond the limits of detection of the inspection method specified in the original issue of the Gulfstream Customer Bulletin applicable to each model aircraft. This AD mandates the Gulfstream requirement for an additional eddy current inspection to be performed if cracks are found using the original ultrasonic inspection.