AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Sikorsky S- 76 Series Helicopters
AD/S-76/71 Rotor Brake Disc 4/2003 TX
Applicability: Model S - 76A, B, and C helicopters.
Requirement: 1. Determine the manufacturer of each rotor brake disc (RBD) by examining the part number (P/N) markings and accomplish the following requirements based on the identification of the RBD.
- If the P/N is 76363-09101-102, the manufacturer is Goodyear. No further action is required by this directive.
b. If the P/N 76363-09103-102 is pressure stamped on the RBD, the manufacturer is BF Goodrich. No further action is required by this directive.
c. If the P/N 76363-09103-102 is electrolytically etched on the RBD, the manufacturer is Parker Hannifin Corporation (PHC).
- For each PHC RBD with a P/N 76363-0913-102 and serial number (S/N) other than 38 through 379, remark the P/N as 76363-090103-105 using the vibropeen method. After remarking no further action is required.
ii. If the RBD serial number or the manufacturer cannot be determined and for RBD’s with P/N 76363-09103-102 and S/N’s 38 through 379, reidentify or mark the P/N as 76363-09103-104, or replace the RBD in accordance with requirement 3 of this directive.
2. For RBD’s with P/N 76363-0103-104, inspect the RBD for cracks as detailed in Figure 1.
- If a crack is found extending through the entire RBD thickness as detailed in Figure 1, View A, replace the RBD with a serviceable RBD other than P/N 76363-09103-104.
b. If 2 or more surface cracks are found located between adjacent boltholes as shown in Figure 1, View B, replace the RBD with a serviceable RBD other than P/N 76363-09103-104.
c. If a surface crack, or surface cracks are found separated by boltholes as shown in Figure 1, View C, replace the RBD with a serviceable RBD other than P/N 76363-09103-104, or deactivate the RBD before further flight.
Note 1: Short “glazing” cracks are not a cause for rejection.
3. Replace the PHC RBD, P/N 76363-09103-104 with a serviceable RBD other than P/N 76363-09103-104.
Figure 1 RBD Inspection Limits.
Note 2: FAA AD 2003-04-15 Amdt 39-13064 refers.
Compliance: 1. Before further flight.
2. Before the first flight of the next day following any day in which the RBD was used.
3. Within 60 days from the effective date of this directive.
This Airworthiness Directive becomes effective on 4 March 2003.
Background: Certain rotor brake discs were found to be manufactured using an incorrect heat treatment process of the disc. This can lead to premature cracking and subsequent failure of the discs. This directive requires identifying certain discs, inspection of these discs and eventual replacement of these discs. Failure of the disc could cause damage to the rotor blades, nearby hydraulic and fuel lines, and subsequent loss of control of the helicopter.
James Coyne
Delegate of the Civil Aviation Safety Authority 28 February 2003
The above AD is notified in the Commonwealth of Australia Gazette on 4 March 2003.
Overview
The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive AD/S-76/71 on 28 February 2003, under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998). This directive addresses an unsafe condition identified in certain rotor brake discs (RBD) of Sikorsky S-76 Series helicopters, specifically those manufactured using an incorrect heat treatment process. Such manufacturing errors can lead to premature cracking and failure of the discs, potentially resulting in damage to rotor blades, hydraulic and fuel lines, and loss of control of the helicopter. The directive aims to ensure the airworthiness of affected aircraft by mandating the identification, inspection, and replacement of certain rotor brake discs, as specified in the directive. The policy objective is to mitigate the risk of in-flight failure by enforcing timely corrective actions, thereby enhancing aviation safety.
Scope and Application
The Airworthiness Directive (AD) issued under subregulation 39.1 (1) of CAR 1998 applies to all Sikorsky S-76A, B, and C series helicopters. This AD mandates specific actions to address an unsafe condition identified in the rotor brake discs (RBD) of these helicopters. The directive is applicable to any person or entity that owns or operates these helicopter models within the Commonwealth of Australia. The scope of the AD is geographically confined to Australia, but its compliance requirements are mandatory for all relevant aircraft within this jurisdiction. The AD does not explicitly state any exclusions or exemptions but specifies particular actions based on the identification of the RBD's manufacturer and serial number. The directive extends its application through detailed instructions on disc inspection and modification, with specific timelines for compliance. Any non-compliance with this AD could result in the grounding of affected helicopters until the specified actions are completed.
Key Provisions
The Airworthiness Directive (AD) issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998) specifies detailed requirements for certain Sikorsky S-76 Series Helicopters. This AD, designated AD/S-76/71, pertains specifically to the rotor brake discs (RBD) of models S-76A, B, and C helicopters. The directive's applicability is clearly outlined in the first section, which mandates that the following requirements must be met for these particular helicopter models (section 1). The directive requires operators to determine the manufacturer of each rotor brake disc by examining the part number (P/N) markings. Based on the manufacturer identified, operators must follow specific instructions: if the P/N is 76363-09101-102, manufactured by Goodyear, no further action is necessary. If the P/N 76363-09103-102 is pressure stamped, manufactured by BF Goodrich, no further action is necessary. However, if the P/N 76363-09103-102 is electrolytically etched, manufactured by Parker Hannifin Corporation (PHC), operators must remark the P/N as 76363-090103-105 using the vibropeen method. For RBDs with P/N 76363-09103-102 and serial numbers (S/N) other than 38 through 379, no further action is required once remarked. If the serial number or manufacturer is unidentifiable, operators must reidentify or mark the P/N as 76363-09103-104, or replace the RBD as per requirement 3.
The AD imposes specific obligations on operators of Sikorsky S-76 Series Helicopters. Operators must ensure that the rotor brake discs are identified correctly by examining the part number markings and following the specified actions based on the manufacturer. For PHC-manufactured discs with serial numbers 38 through 379, operators must either reidentify the part number or replace the disc. Operators must also inspect the RBDs for cracks as detailed in Figure 1. If any cracks extending through the entire thickness or multiple surface cracks are found, the RBD must be replaced with a serviceable RBD other than P/N 76363-09103-104. If surface cracks are found separated by boltholes, the RBD must either be replaced or deactivated before further flight. Short "glazing" cracks are not considered a cause for rejection.
Breaching the requirements of this Airworthiness Directive can lead to significant consequences. Operators must comply with the directive before further flight, before the first flight of the next day following any day in which the RBD was used, and within 60 days from the effective date of this directive (section 3). Failure to comply with these requirements could result in the continued operation of potentially unsafe aircraft, leading to severe safety risks, including damage to the rotor blades, hydraulic and fuel lines, and loss of control of the helicopter. Non-compliance may also result in enforcement actions by the Civil Aviation Safety Authority (CASA), which could include fines, penalties, or other regulatory measures. The directive emphasizes the importance of adhering to these requirements to ensure the continued airworthiness and safety of the affected helicopter models.