COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
DHC-6 (Twin Otter) Series Aeroplanes
AD/DHC-6/33
Amdt 4
Elevator Root and Nose Ribs 4/92
Applicability: Model DHC-6 series.
Requirement: 1. Inspect the elevator root rib for cracks in accordance with de Havilland Service Bulletin 6/399 Revision E.
If cracking is present, incorporate de Havilland modification 6/1769 before further flight.
2. Incorporate de Havilland modification 6/1769.
Note: Transport Canada AD CF-82-21 R1 refers.
Compliance: 1. At intervals not to exceed 600 hours time in service, until modification 6/1769 is incorporated.
2. Prior to 1 January 1996 or 15 000 hours airframe time in service, whichever occurs later.
The compliance of the previous issue of this Directive was:
Unless already accomplished, inspect within 200 hours time in service after 31 October 1983, with repeat inspections at intervals not exceeding 600 hours time in service until modification 6/1769 is incorporated.
This Amendment is effective from 2 April 1992.
Background: Cracking has occurred in the elevator root rib. Amendment 4 is issued to align this Directive with a revision of the relevant Country of Origin AD which requires terminating action in lieu of ongoing repetitive inspections.
Overview
The Civil Aviation Regulations 1998, as amended by AD/DHC-6/33 Amendment 4, pertains to the DHC-6 (Twin Otter) series aeroplanes, specifically addressing the elevator root ribs and nose ribs. This legislation was enacted to rectify the issue of cracking in the elevator root ribs of these aircraft models. The problem that prompted this legislation was the occurrence of structural cracks in the elevator root ribs, which could compromise the safety of the aircraft during operation. The Australian Government, through the Civil Aviation Safety Authority (CASA), introduced this amendment to ensure compliance with the de Havilland modification 6/1769 and to align with the revision of the relevant Country of Origin Airworthiness Directive issued by Transport Canada. The policy objective behind this amendment is to enhance aviation safety by mandating specific modifications and inspections to mitigate the risk of structural failure in the elevator root ribs. This amendment is effective from 2 April 1992 and requires inspections and modifications to be carried out at intervals not exceeding 600 hours of time in service until the modification 6/1769 is incorporated.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Civil Aviation Safety Authority Schedule of Airworthiness Directives for the DHC-6 (Twin Otter) series aeroplanes. This regulation applies to all aircraft within the DHC-6 series, necessitating inspections and modifications to the elevator root ribs to ensure airworthiness. The requirement involves inspecting the elevator root rib for cracks in accordance with de Havilland Service Bulletin 6/399 Revision E and incorporating de Havilland modification 6/1769 if any cracking is detected before further flight. Compliance with these directives must occur at intervals not exceeding 600 hours of time in service until the modification is implemented and before 1 January 1996 or 15,000 hours of airframe time in service, whichever comes later. This amendment, which became effective from 2 April 1992, aligns with the Transport Canada AD CF-82-21 R1, reflecting international safety standards and addressing the issue of cracking in the elevator root rib.
Key Provisions
The Civil Aviation Regulations 1998, specifically Part 39 - 105, includes a schedule of airworthiness directives for various aircraft models, including the DHC-6 (Twin Otter) series aeroplanes. Amendment 4 (AD/DHC-6/33) addresses issues related to the elevator root rib and nose ribs of these aircraft. According to section 1, operators must inspect the elevator root rib for cracks in line with de Havilland Service Bulletin 6/399 Revision E. If any cracking is detected, de Havilland modification 6/1769 must be implemented before further flights are undertaken. Section 2 mandates the incorporation of de Havilland modification 6/1769, with reference to Transport Canada AD CF-82-21 R1.
The obligations imposed on the operators by these provisions are clear. Section 1 requires rigorous and regular inspections of the elevator root rib for any signs of cracks. This must be conducted in accordance with the specifications provided in de Havilland Service Bulletin 6/399 Revision E. Should cracks be found, the operator must immediately incorporate de Havilland modification 6/1769, ensuring the aircraft meets the required safety standards before any further operations. Additionally, Section 2 mandates that de Havilland modification 6/1769 must be implemented, regardless of whether cracks are detected. This is to ensure the long-term structural integrity and safety of the aircraft.
Failure to comply with these airworthiness directives can result in serious consequences. Section 3 outlines the compliance requirements, stipulating that inspections must be conducted at intervals not exceeding 600 hours of time in service until the modification 6/1769 is incorporated. Additionally, if the aircraft has not yet reached 15,000 hours of airframe time in service, inspections must be carried out before 1 January 1996. Breach of these requirements may lead to penalties, including fines or other sanctions as prescribed by the Civil Aviation Regulations. The specific penalties can vary but may include substantial financial penalties and potential grounding of the aircraft until compliance is achieved.