AD/G1159/32 - Flap, Auxiliary and Thrust Reverser Hydraulic Shut-Off Valves - Inspection and Replacement

Overview

The Civil Aviation Regulations 1998, as amended by F2006B10035, address the critical issue of hydraulic system reliability in Gulfstream (Grumman) G1159 and G-IV Series aeroplanes, specifically targeting the auxiliary and thrust reverser hydraulic shut-off valves. Enacted by the Commonwealth of Australia, the regulations were introduced to ensure the safety and airworthiness of these aircraft by mandating the inspection and replacement of the aforementioned shut-off valves. The policy objective is to prevent the potential loss of all combined and auxiliary hydraulic system functions, which could occur due to the failure of the brazing of the solenoids fitted to the shut-off valves caused by fatigue. Compliance with the regulations is enforced by requiring inspections and actions to be performed within specified timeframes as detailed in Gulfstream Aerospace Customer Bulletin No. 349. This legislative instrument, issued by the Civil Aviation Safety Authority, is designed to mitigate the risk of in-flight system failures that could compromise the safety of the aircraft and its occupants. By mandating specific inspection and replacement procedures, the regulations aim to maintain the integrity of the hydraulic systems, ensuring that the aircraft remains airworthy and compliant with safety standards. The requirement to adhere to the manufacturer's bulletin underscores the importance of following detailed maintenance protocols to avert potential hazards associated with valve malfunctions.

Scope and Application

The Civil Aviation Safety Authority (CASA) has issued an Airworthiness Directive (AD) concerning the Gulfstream (Grumman) G1159 and G-IV Series Aeroplanes, specifically addressing the flap, auxiliary, and thrust reverser hydraulic shut-off valves. This directive applies to all models of these aircraft and any spares identified as part of the affected shut-off valve assemblies, with the specific part number 1159SCH211-7. The regulation aims to ensure the continued airworthiness of these aircraft by mandating inspections and replacements of the hydraulic shut-off valves to prevent potential loss of hydraulic system functionality. The directive requires compliance with Gulfstream Aerospace Customer Bulletin No. 349 and specifies that inspections must be carried out before further flight after 17 July 1984, with certain steps performed in accordance with the outlined actions in the requirement document, and inspections must not exceed intervals of seven days where specified. The geographic reach of this regulation is national, applying to all aircraft registered within Australia and operated under Australian jurisdiction. There are no stated exclusions or exemptions in this directive; it applies universally to the specified aircraft and parts. The application of this AD can be further detailed or modified through subordinate instruments issued by CASA.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives, addresses the maintenance and inspection requirements for Gulfstream (Grumman) G1159 and G-IV series aeroplanes. In particular, AD/G1159/32 mandates the inspection and replacement of flap, auxiliary, and thrust reverser hydraulic shut-off valves (section 8/84). This directive applies to all models and spares assemblies with part number 1159SCH211-7 (section 1). The requirement is derived from Gulfstream Aerospace Customer Bulletin No. 349 (section 2). Operators must comply with this directive by performing the initial inspection and necessary actions as specified in the requirement document before any further flight following 17 July 1984 (section 3). If the conditions in step 1C of the requirement document apply, inspections must be conducted no less frequently than every seven days (section 4). Operators of Gulfstream G1159 and G-IV series aeroplanes must ensure compliance with AD/G1159/32 by adhering to the specified inspection and replacement procedures. This involves closely following the Gulfstream Aerospace Customer Bulletin No. 349 to ensure that the shut-off valves are inspected and any necessary actions are taken before the aeroplane is flown again post 17 July 1984. If the specific condition outlined in step 1C of the requirement document applies, operators must conduct inspections at intervals not exceeding seven days. Failure to comply with these directives could result in serious safety risks, as the manufacturer has indicated that failure of the brazing of the solenoids fitted to the shut-off valves due to fatigue could lead to the loss of all combined and auxiliary hydraulic system functions. Failure to comply with AD/G1159/32 can result in severe civil and criminal penalties. Under the Civil Aviation Act 1988, non-compliance with airworthiness directives is an offence that can lead to significant fines and potential imprisonment. Specifically, the maximum penalty for contravening airworthiness directives can be substantial, reflecting the critical nature of these safety measures. Additionally, CASA has the authority to take enforcement actions, including grounding the aircraft until compliance is achieved, which can have significant operational and financial repercussions for the operator. These measures underscore the importance of adhering to the requirements set out in the airworthiness directives to ensure the continued safety and airworthiness of the aircraft.