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.
McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters
AD/HU 369/109 Tail Rotor Gearbox Attachment 10/2002
Applicability: MD Helicopters Inc. Model 369D, 369E, 369F, and 369FF helicopters, modified in accordance with Aerometals Supplemental Type Certificate (STC) SH5055NM or SH4801NM.
Requirement: 1. Initial Inspection and bolt replacement:
- Carry out an inspection of the tail rotor gearbox attachment bolts to determine the part number.
b. If the part number cannot be determined or if the bolt is not P/N NAS1304- 26, replace the bolt with bolt, P/N NAS1304-26.
c. Torque the bolt to 100-110 in- lbs and apply slippage mark.
d. Remove the tailboom control rod and determine the number of threads protruding from each nutplate on the internal surface of the aft tailboom frame casing, P/N 369D23503, as shown in Figure 1 of this Directive. At least one thread must protrude. If more than four threads protrude, add an additional washer, P/N AN960D416, under the bolt head.
e. Torque the bolt to 100-110 in- lbs and re apply slippage mark.
2. Repetitive Inspection:
- Re check the attachment bolts for correct torque and re-torque if necessary.
b. Re apply slippage mark if re-torque is required.
Note: FAA AD 2002-13-05 Amdt 39-12793 refers.
Figure 1 – Inspection Location
Compliance: 1. Initial Inspection and bolt replacement:
Within 25 flight hours from the effective date of this Directive.
2. Repetitive Inspection:
Between 2 and 10 hours flight hours after initial inspections have been carried out, thereafter between 2 and 10 flight hours until no further bolt movement occurs during torque check.
This Airworthiness Directive becomes effective on 3 October 2002.
Background: The bolts that attach the tail rotor gearbox have been found to be of inadequate grip length. This Directive introduces an inspection and possible replacement of the bolts to ensure the integrity of the gearbox for safe operation of the helicopter.
James Coyne
Delega te of the Civil Aviation Safety Authority 23 August 2002
The above AD is notified in the Commonwealth of Australia Gazette on 11 September 2002.
Overview
The Airworthiness Directive issued by the Civil Aviation Safety Authority (CASA) in 2002 under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998) addresses a safety issue with the tail rotor gearbox attachment bolts of certain MD Helicopters Inc. Model 369D, 369E, 369F, and 369FF helicopters that have been modified in accordance with Aerometals Supplemental Type Certificate (STC) SH5055NM or SH4801NM. The problem identified was that the bolts attaching the tail rotor gearbox were found to be of inadequate grip length, which could compromise the integrity of the gearbox and thus the safe operation of the helicopter. This Airworthiness Directive mandates an initial inspection and, if necessary, replacement of the bolts to rectify the identified unsafe condition, with specific timelines for compliance to ensure that the corrective action is implemented without undue delay.
Scope and Application
The Airworthiness Directive (AD) issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 applies to specific models of MD Helicopters Inc. helicopters, namely the Model 369D, 369E, 369F, and 369FF, that have been modified according to Aerometals Supplemental Type Certificates (STC) SH5055NM or SH4801NM. The directive mandates actions to address an identified unsafe condition, namely inadequate grip length of the bolts attaching the tail rotor gearbox. This requirement extends to the inspection and possible replacement of the bolts, as well as ensuring proper torque settings and the correct number of threads protruding from the nutplates. The AD is applicable within the Commonwealth of Australia and was issued by the Civil Aviation Safety Authority (CASA) delegate, James Coyne, on 23 August 2002, and it became effective on 3 October 2002. The directive specifies the initial inspection and bolt replacement within 25 flight hours from the effective date, followed by repetitive inspections at intervals between 2 and 10 flight hours until no further bolt movement occurs during the torque check. This directive is not subject to any exclusions, exemptions, or thresholds, and its requirements must be strictly followed to ensure the safe operation of the specified helicopters.
Key Provisions
The Airworthiness Directive (AD) AD/HU 369/109, issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998, applies specifically to MD Helicopters Inc. Models 369D, 369E, 369F, and 369FF helicopters that have been modified according to Aerometals Supplemental Type Certificates (STC) SH5055NM or SH4801NM. The directive mandates a series of actions to address the identified issue of inadequate grip length in the tail rotor gearbox attachment bolts, which is critical for the safe operation of these helicopters. Section (a) of the AD specifies the circumstances under which the actions must be taken, while section (b) outlines the instructions for carrying out these actions. Section (c) indicates the timeline for compliance, with initial inspections and bolt replacements required within 25 flight hours from the directive's effective date.
The AD imposes several obligations on the operators of the specified helicopters. Firstly, it requires an initial inspection of the tail rotor gearbox attachment bolts to determine their part number. If the part number cannot be determined or if the bolt is not P/N NAS1304-26, the directive mandates that the bolt be replaced with one of the specified part number. Furthermore, operators must torque the bolt to a specified range of 100-110 in-lbs and apply a slippage mark. Additionally, the directive requires operators to inspect the number of threads protruding from each nutplate on the internal surface of the aft tailboom frame casing, P/N 369D23503. If more than four threads protrude, an additional washer, P/N AN960D416, must be added under the bolt head, followed by re-torqueing and reapplying the slippage mark. A repetitive inspection is also required between 2 and 10 flight hours after the initial inspections, continuing until no further bolt movement occurs during the torque check.
Failure to comply with the provisions of this Airworthiness Directive may result in civil or criminal consequences. The AD does not specify maximum penalties within the text, but non-compliance could potentially lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions may include fines, suspension or revocation of airworthiness certificates, and other regulatory sanctions. Operators are therefore obligated to adhere strictly to the timelines and instructions set out in the directive to ensure the continued airworthiness and safety of the affected helicopters.