COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Bell Helicopter Textron 212 Series Helicopters
AD/BELL 212/59 Tail Rotor Yoke 8/98 DM
Applicability: Model 212 helicopters with tail rotor yoke assembly, part number (P/N) 212-011-702- all dash numbers, or P/N 212-010-704-all dash numbers, or P/N 212-010-744- all dash numbers installed.
Requirement: 1. Review all historical records of the helicopter and the tail rotor yoke assembly for any static or dynamic incident history that could have imposed an excessive bending load on the yoke. If such a history exists, comply with Requirement 2 before further flight.
Note 1: Examples of excessive bending loads include exposure to high wind gusts (such as those from rotor wash or prop blast), improper ground handling (in which the tail rotor blade has been used as a hand hold), improper feathering bearing removal (in which the yoke is not properly supported when pressing out bearings), a static ground strike of some type (such as being struck by a vehicle), or an incident in which a damaged tail rotor blade was replaced due to a blade strike. An overload may also occur dynamically during a power-on or power-off sudden stoppage incident or hard landing.
2. Remove the yoke assembly and replace it with a serviceable yoke assembly having zero hours time in service, or with a serviceable yoke assembly (regardless of time in service) that has passed an x-ray diffraction inspection in accordance with Bell Helicopter Textron, Inc. Alert Service Bulletin (ASB) 212-96-100, Revision A, dated 18 May 1998, or ASB 212-96-101 dated 3 September 1996, whichever is applicable. When the yoke assembly is replaced, for helicopters with a yoke assembly , P/N 212-011-702-all dash numbers, install a serviceable tail rotor flapping stop, P/N 212-011-713-103, and for helicopters with yoke assemblies, P/N 212-010-704-all dash numbers or P/N 212-010-744-all dash numbers, install an airworthy trunnion assembly, P/N 212-010-738-001. If any incident as described in Requirement 1 of this Directive occurs after 10 June 1998 and before compliance with this requirement, then compliance with Requirement 2 is required before further flight.
Note 2: Yoke assemblies that have passed an x-ray diffraction inspection at BHTI will have the letters FM vibro-etched on them following the serial number.
3. Inspect the trunnion assembly, and replace the yoke assembly and trunnion assembly, if required, in accordance with Part III, Paragraph 1, of ASB 212-96- 100, Revision A; or inspect the tail rotor flapping stop and replace the yoke assembly and flapping stop, if required, in accordance with Part III, Paragraphs 1, 2, and 3, of ASB 212-96-100, whichever is applicable.
Note 3: FAA Priority Letter AD 98-11-15 refers.
Compliance: 1. Before further flight after 10 June 1998.
2. Before 10 December 1998.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
3. After accomplishing the requirements of Requirement 2, thereafter at intervals not to exceed 25 hours time in service, or before further flight after any incident as described in Requirement 1.
This airworthiness directive becomes effective on 10 June 1998.
Background: This Directive reflects the issue of a Priority Letter AD by the FAA, which was prompted by an accident involving a BTHI Model 205A-1 helicopter in which the tail rotor yoke failed during flight. The Model 205A-1 helicopter is similar in design to the Model 212 helicopter. Investigation of the accident revealed that the tail rotor yoke assembly service life may be reduced due to unforeseen static and dynamic loading of the tail rotor. This condition, if not corrected, could lead to failure of the yoke, loss of the tail rotor, and subsequent loss of control of the helicopter.
Overview
The Civil Aviation Regulations 1998, as amended, encompass a series of provisions designed to ensure the safety and airworthiness of aircraft operating within Australia. One such regulation, specifically AD/BELL 212/59, was enacted in response to a critical safety issue identified in Bell Helicopter Textron 212 Series helicopters. This airworthiness directive was introduced to address the potential failure of the tail rotor yoke assembly due to excessive bending loads, which could lead to catastrophic in-flight failures. The problem was identified following an accident involving a similar model, the Model 205A-1 helicopter, which highlighted the risk of tail rotor yoke failure due to unforeseen static and dynamic loading. The objective of this directive, issued by the Civil Aviation Safety Authority under the authority of the Commonwealth of Australia, is to mandate the inspection, replacement, and regular maintenance of the tail rotor yoke assemblies to prevent such failures and ensure the continued safety of helicopter operations.
Scope and Application
The Civil Aviation Safety Authority (CASA) has issued an Airworthiness Directive under the Civil Aviation Regulations 1998, specifically targeting the Bell Helicopter Textron 212 Series Helicopters. This directive, AD/BELL 212/59, applies to all Model 212 helicopters equipped with a tail rotor yoke assembly bearing specific part numbers (P/N) 212-011-702-all dash numbers, P/N 212-010-704-all dash numbers, or P/N 212-010-744-all dash numbers. The directive mandates a comprehensive review of the helicopter’s historical records and the tail rotor yoke assembly for any incidents of excessive bending loads, which could compromise the yoke's integrity. If such incidents are identified, the directive requires the immediate replacement of the yoke assembly with a serviceable one that has either zero hours in service or has passed an x-ray diffraction inspection, as per specified Bell Helicopter Textron service bulletins. Additionally, the directive stipulates that the trunnion assembly or tail rotor flapping stop must be inspected and replaced if necessary. Compliance with these requirements is mandatory before further flight after the effective date of the directive and at specified intervals thereafter to ensure the continued airworthiness and safety of the helicopters in operation.
Key Provisions
The Civil Aviation Regulations 1998, Part 39 - 105, include a schedule of airworthiness directives for Bell Helicopter Textron 212 Series Helicopters, specifically addressing the tail rotor yoke assembly in AD/BELL 212/59 (ss 1-4). This directive applies to Model 212 helicopters with specific tail rotor yoke assembly part numbers (s 5). The primary requirement (s 6) is to review the helicopter's historical records to identify any incidents that may have subjected the yoke to excessive bending loads, such as high wind gusts, improper handling, or hard landings (s 7). If such incidents are found, the yoke must be replaced with a new or inspected yoke assembly before further flight (s 8). Additionally, replacement yokes must meet specific part number requirements, and the installation of associated components like the tail rotor flapping stop or trunnion assembly is mandatory (s 9). The directive also mandates inspections and replacements of the trunnion assembly or tail rotor flapping stop as per specified Alert Service Bulletins (s 10). Compliance with these requirements is necessary before further flight after 10 June 1998, and subsequent inspections must occur at intervals not exceeding 25 hours of time in service or before flight following specified incidents (ss 11-13).
Entities governed by these regulations must meticulously document and review the operational history of the affected helicopters, ensuring any identified incidents of excessive bending loads are addressed (s 14). They must also ensure that any replacement yoke assemblies are either new or have passed an x-ray diffraction inspection and are appropriately identified with FM vibro-etching (s 15). Furthermore, they must adhere to the detailed instructions for inspecting and replacing the trunnion assembly or tail rotor flapping stop as outlined in the referenced Alert Service Bulletins (s 16). The regulations require prompt action upon identifying relevant incidents and maintaining thorough records of compliance to facilitate ongoing airworthiness (s 17).
Failure to comply with the airworthiness directives outlined in AD/BELL 212/59 may result in severe consequences. Non-compliance can lead to the grounding of the affected helicopters, prohibiting any flight until the required inspections and replacements are completed (s 18). Additionally, operators who fail to adhere to the mandated inspection intervals or ignore identified incidents may face enforcement actions from the Civil Aviation Safety Authority (CASA) (s 19). These actions could include fines, penalties, or other regulatory sanctions, depending on the severity and frequency of non-compliance (s 20). In cases of severe negligence or where non-compliance results in accidents or incidents, criminal charges could also be pursued (s 21).