COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters
AD/HU 369/90 Tail Rotor Blade Abrasion Strip 5/95
DM
Applicability: Model 369 series helicopters, with tail rotor blade assembly part numbers listed in McDonnell Douglas Helicopter Systems SIN HN-238, DN-187, EN-80, or FN-66.
Requirement: 1. Inspect the tail rotor blade abrasion strip for debonding from the tail rotor blade. Prior to conducting the inspections, remove any abrasion tape from the tail rotor blade.
If the inspection reveals debonding, replace the tail rotor blade with an airworthy blade that has been modified by installation of rivets, and install 304 stainless steel abrasion tape (.0027 inch thick) over the inboard end of the abrasion strip in accordance with steps B through H of Part I of the Accomplishment Instructions of McDonnell Douglas SIN HN-238, DN-187, EN-80, or FN-66.
If the inspection reveals no debonding, install 304 stainless steel abrasion tape (.0027 inch thick) over the inboard end of the abrasion strip in accordance with steps B through H of Part I of the Accomplishment Instructions of McDonnell Douglas Helicopter Systems SIN HN-238, DN-187, EN-80, or FN-66.
2. Replace the affected tail rotor blades in shipsets with tail rotor blades that contain the new-design abrasion strips in accordance with Part II of the Accomplishment Instructions of SIN HN-238, DN-187, EN-80, or FN-66. Once the new-design abrasion strips are installed on the tail rotor blades, the tail rotor assembly part number changes as follows:
Old Tail Rotor Assembly No New Tail Rotor Assembly No 369A1613-7 369A1613-11
369A1613-503 369A1613-507
369A1613-505 369A1613-507
369A1613-509 369A1613-507
369D21606 369D21606-511
369D21606-509 369D21606-511
369D21613-11 369D21613-11N
369D21613-31 369D21613-31N
369D21613-41 369D21613-61
369D21613-51 369D21613-61
369D21613-71 369D21613-61
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
369D21615 369D21615-N
369D21615-21 369D21615-31
369D21615-41 369D21615-31
421-088 421-088-11
Note: FAA AD 95-03-11 Amdt 39-9147 refers.
Compliance: 1. Unless already accomplished, within 25 hours time in service after 15 March 1995 or prior to 15 June 1995, whichever occurs first, and thereafter at intervals not to exceed 100 hours time in service; until Requirement 2 of this Directive is accomplished.
2. Within 1,000 hours time in service after 15 March 1995.
Background: The FAA received several reports of incidents where tail rotor blade riveted abrasion strips debonded and separated during flight, which resulted in a severe out-of-balance condition and subsequent separation of the tail rotor gearbox from the helicopter.
Overview
The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority, was enacted to address safety concerns related to the airworthiness of aircraft. The McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters Tail Rotor Blade Abrasion Strip AD/HU 369/90 was introduced to mitigate risks associated with tail rotor blade abrasion strips debonding and separating during flight, which could lead to severe imbalance and subsequent mechanical failure. The directive was issued by the Civil Aviation Safety Authority to ensure compliance with safety standards, thereby protecting the integrity of the aircraft and the safety of its occupants. The objective of this directive is to mandate regular inspections and necessary replacements of tail rotor blade abrasion strips to prevent debonding and subsequent catastrophic failures.
Scope and Application
The Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, specifically AD/HU 369/90, applies to McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters with specific tail rotor blade assembly part numbers. This regulation mandates that operators and maintenance personnel inspect the tail rotor blade abrasion strip for debonding and replace it if necessary, with detailed procedures outlined for the installation of new abrasion strips. The requirement includes removing any existing abrasion tape before inspection and adhering to specific installation instructions to ensure airworthiness. The geographic reach of this directive is national, applying across all Australian jurisdictions, as it is a Commonwealth regulation under the Civil Aviation Regulations 1998. Compliance with these directives is mandatory and must be achieved within specified timeframes, with inspections and replacements scheduled according to strict intervals. The directive extends its application through subordinate instruments, which provide detailed procedures for accomplishing the required tasks.
Key Provisions
The Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998, has issued an airworthiness directive (AD) concerning the McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, specifically targeting the tail rotor blade abrasion strip (AD/HU 369/90). This directive applies to Model 369 series helicopters with specific tail rotor blade assembly part numbers (Section 1). The primary requirement of this directive is to inspect the tail rotor blade abrasion strip for signs of debonding from the blade (Section 2). If debonding is detected during the inspection, the affected tail rotor blade must be replaced with an airworthy blade that has been modified with rivets, and a 304 stainless steel abrasion tape (.0027 inch thick) must be installed over the inboard end of the abrasion strip (Section 3). If no debonding is found, the abrasion tape must still be installed as specified (Section 4). Furthermore, the affected tail rotor blades in shipsets must be replaced with blades containing new-design abrasion strips (Section 5). These new blades will have altered part numbers upon installation of the new-design abrasion strips (Section 6).
The AD imposes several obligations on the parties governed by it. Operators and maintainers of the affected helicopters must ensure that the required inspections are carried out within 25 hours time in service after 15 March 1995 or prior to 15 June 1995, whichever comes first, and subsequently at intervals not exceeding 100 hours time in service until the second requirement is fulfilled (Section 7). Additionally, the replacement of tail rotor blades with those containing new-design abrasion strips must occur within 1,000 hours time in service after 15 March 1995 (Section 8). Compliance with these directives is essential to ensure the continued airworthiness and safety of the helicopters in question.
Failure to comply with the requirements of this AD may result in severe consequences, including potential flight safety risks. The Federal Aviation Administration (FAA) reported incidents where debonding of the tail rotor blade abrasion strips led to an out-of-balance condition and the subsequent separation of the tail rotor gearbox from the helicopter, which can be catastrophic (Section 9). While the AD does not specify explicit penalties or legal consequences for non-compliance, the potential for severe accidents and the overarching safety regulations imply that non-compliance could result in serious civil or criminal penalties under broader aviation safety laws. Operators and maintainers must adhere strictly to these directives to avoid any risk to flight safety and to comply with aviation safety regulations.