AD/BELL 412/13 - Tail Rotor Trunnion Bearing Housing

Overview

The Civil Aviation Regulations 1998, specifically within PART 39 - 105, addresses the safety concerns related to the Bell Helicopter Textron 412 Series Helicopters through Airworthiness Directives. Enacted by the Civil Aviation Safety Authority, this regulation targets a critical issue identified in the tail rotor trunnion bearing housing of certain model 412 helicopters. The directive mandates that these aircraft undergo specific inspections and maintenance actions to mitigate the risk of structural failure, which could lead to excessive tail rotor vibration and potential loss of control. The policy objective is to ensure the continued airworthiness and safety of these helicopters by enforcing stringent compliance with the specified inspection and repair protocols. This legislative instrument was introduced to fill a significant safety gap identified in the operational integrity of the specified helicopter models. By requiring adherence to Bell Alert Service Bulletin No. 412-86-25, Revision A, the regulation aims to prevent catastrophic failures that could result from the substandard dimensions of the trunnion bearing housing end web. The directive mandates compliance within a critical timeframe, ensuring that the necessary inspections and repairs are performed either at the next 20-hour inspection or within 150 hours of time in service, whichever occurs first, following the issuance date of 31 July 1986.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses airworthiness directives for aircraft, including those issued by the Civil Aviation Safety Authority (CASA). This legislative instrument applies to a defined series of Bell Helicopter Textron 412 helicopters, namely those with serial numbers (S/N) ranging from 33001 to 33118, 33120, and 33121. The requirement outlined in AD/BELL 412/13 pertains to the tail rotor trunnion bearing housing and mandates compliance with Bell Alert Service Bulletin No. 412-86-25, Revision A. The directive necessitates action at the next 20-hour inspection and then at each subsequent 20-hour inspection until the specified conditions are met. Specifically, compliance must be achieved within 150 hours of time in service or 60 days from 31 July 1986, whichever comes first. This regulation ensures the airworthiness and safety of the affected helicopters by addressing a critical issue where the trunnion bearing housing end web was found below specified dimensions, potentially leading to excessive tail rotor vibration and loss of control. The scope of this Act is confined to the specified model and serial numbers of the Bell 412 helicopters, with no broader application to other aircraft or models.

Key Provisions

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, address the safety of Bell Helicopter Textron 412 Series Helicopters through Airworthiness Directives. One such directive, AD/BELL 412/13, pertains to the tail rotor trunnion bearing housing. This directive applies to all model 412 helicopters with serial numbers ranging from 33001 to 33118, 33120, and 33121. The requirement outlined in this directive mandates that operators must follow Bell Alert Service Bulletin No. 412-86-25, Revision A. Compliance is structured in two parts: Part I requires action at the next 20-hour inspection and then at every subsequent 20-hour inspection until Part II is fulfilled. Part II stipulates that the directive must be adhered to within 150 hours of time in service or within 60 days, whichever comes first, following 31 July 1986. The directive imposes several obligations on the operators of Bell Helicopter Textron 412 Series Helicopters. Firstly, operators must ensure that the actions detailed in Bell Alert Service Bulletin No. 412-86-25, Revision A, are carried out meticulously. This involves inspecting and potentially modifying the tail rotor trunnion bearing housing to meet the specified dimensions. The obligation extends to maintaining detailed records of all inspections and actions taken to comply with the directive. This ensures that the helicopter remains airworthy and reduces the risk of in-flight failure, which could lead to serious safety concerns. Failure to comply with the requirements of AD/BELL 412/13 can result in significant civil and criminal consequences. Under the Civil Aviation Regulations 1998, non-compliance may lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Civil penalties can include fines and other monetary penalties as determined by CASA. Furthermore, persistent non-compliance or severe violations may result in criminal charges, leading to imprisonment for individuals responsible for the oversight of the aircraft. The exact penalties are not specified in the text, but the potential severity underscores the importance of strict adherence to the directive. In summary, the AD/BELL 412/13 directive is a critical component of ensuring the safety of Bell Helicopter Textron 412 Series Helicopters. Operators are required to follow precise actions to address the tail rotor trunnion bearing housing issue, with significant obligations to maintain compliance and detailed records. The potential civil and criminal consequences for non-compliance highlight the necessity for rigorous adherence to the directive, thereby safeguarding the integrity and safety of air travel.