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 CASR 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.
McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters
AD/HU 369/111 Tail Rotor Blade Pitch Horn 6/2003
TX
Applicability: Model 369A, D, E, H, HE, HM, HS, F, and FF helicopters; with tail rotor blades, part number 369D21640-501, 369D21641-501, 369D21642-501, 369D21643-501, 500P3100-101, 500P3100-301, 500P3300-501, or 500P3500-701, installed.
Requirement: 1. Perform a one-time visual inspection of each tail rotor blade pitch horn for a crack or corrosion in the area indicated by Note 2 in Figure 1 of this Directive. Paint removal in accordance with Note 1 of Figure 1 of this Directive is not required for the visual inspection.
2. This Directive establishes a new retirement life of 400 hours time in service for affected tail rotor blades. For helicopters with an affected tail rotor blade installed that has between 390 and 700 hours time in service, remove and replace the tail rotor blade with a serviceable blade.
3. Revise the helicopter Airworthiness Limitations section of the maintenance manual to indicate the new retirement for affected tail rotor blades.
For helicopters with a tail rotor blade installed that has more than 700 hours time in service, a one-time special flight permit to fly to a repair facility may be issued only upon completion of an eddy current surface scan of each affected pitch horn (refer Figure 1). Paint removal in accordance with Note 1 of Figure 1 of this Directive is required for the surface scan. If a crack is found, before further flight, replace the cracked tail rotor blade with a serviceable blade.
Compliance: 1. Before further flight after 17 April 2003.
2. Within 10 hours time in service after 17 April 2003.
3. Before 30 April 2003.
This Airworthiness Directive becomes effective on 17 April 2003.
Background: The FAA received two reports of cracked tail rotor blade pitch horns that failed during flight. In both occurrences, the pilot was able to land the helicopter without further incident. Investigation revealed that the cause of the failures was a fatigue crack in the pitch horns that developed before the tail rotor blade reached its retirement life.
David Villiers
Delegate of the Civil Aviation Safety Authority 16 April 2003
The above AD is notified in the Commonwealth of Australia Gazette on 17 April 2003.
Overview
The Civil Aviation Safety Authority (CASA) issued the Airworthiness Directive AD/HU 369/111 on 16 April 2003, as a legislative instrument under subregulation 39.1(1) of the Civil Aviation Safety Regulations 1998 (CASR 1998). This directive addresses safety concerns related to the tail rotor blades of McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, specifically targeting those with certain part numbers. The directive was introduced following reports of cracked tail rotor blade pitch horns that failed during flight, prompting the need for stringent safety measures to prevent similar incidents in the future. The policy objective of this directive is to ensure the continued airworthiness of affected helicopters by mandating specific inspections, replacements, and maintenance manual updates to mitigate the identified safety risks.
Scope and Application
The Airworthiness Directive issued under the Civil Aviation Safety Regulations 1998 applies specifically to McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, including models 369A, D, E, H, HE, HM, HS, F, and FF, which are equipped with tail rotor blades bearing certain part numbers. The directive mandates a series of inspections, replacements, and documentation updates to ensure the continued airworthiness and safety of these helicopters. The requirement to perform a visual inspection for cracks or corrosion in the tail rotor blade pitch horns applies to all specified models, regardless of their current location within Australia. The directive also sets a new retirement life of 400 hours for affected tail rotor blades, with specific instructions for blades that have accumulated between 390 and 700 hours of service. For blades exceeding 700 hours, a special flight permit may be granted following an eddy current surface scan, provided that any detected cracks are rectified before further flight. The compliance timeline dictates that inspections and necessary actions must be completed before further flight after April 17, 2003, with specific deadlines for certain actions to be met within 10 hours of the directive's issuance and before April 30, 2003, for the update of the helicopter's maintenance manual. This directive is effective from April 17, 2003, and its scope is enforced across the entire Commonwealth of Australia.
Key Provisions
The Airworthiness Directive (AD) AD/HU 369/111 mandates certain actions to address safety issues identified with the tail rotor blade pitch horns of the McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters (section 1). Specifically, the AD requires a one-time visual inspection of each tail rotor blade pitch horn for cracks or corrosion, as detailed in the requirement section (section 2). Additionally, a new retirement life of 400 hours time in service is established for affected tail rotor blades. For helicopters with blades between 390 and 700 hours time in service, the blades must be removed and replaced with serviceable ones. For those with blades over 700 hours time in service, a special flight permit to fly to a repair facility may be issued after a detailed eddy current surface scan of each affected pitch horn, which requires paint removal.
The AD imposes several obligations on the parties governed by it. Firstly, operators of the specified helicopters must conduct the required visual inspection and, if necessary, replace tail rotor blades as per the new retirement life specified (section 2). Secondly, they must revise the helicopter Airworthiness Limitations section of the maintenance manual to reflect the new retirement life. Lastly, for helicopters with blades over 700 hours time in service, a special flight permit can only be issued after the completion of an eddy current surface scan of each affected pitch horn, and any cracked blade must be replaced before further flight (section 3).
Failure to comply with the AD may lead to several consequences. Although specific civil or criminal penalties are not detailed within the AD, non-compliance could result in the aircraft being deemed unairworthy, leading to grounding of the helicopter. This could have significant operational and financial repercussions for the operators. The AD’s aim is to ensure that all specified actions are taken to prevent potential unsafe conditions that could compromise flight safety.