Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Israel Aircraft Industries, Ltd., Model 1121, 1121A, 1121B, 1123, 1124, 1124A, 1125 Westwind Astra, and Astra SPX series airplanes. This proposal would require repetitive functional tests for proper operation of hydraulic fuses installed in the brake system and emergency hydraulic indicating system; and replacement of any discrepant hydraulic fuse with a new, improved unit. This proposal is prompted by the issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent failure of the hydraulic fuse to operate properly, due to internal corrosion, in the event of an external leak downstream of the fuse, which could result in loss of hydraulic systems.