AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CT7/10 Amdt 1 and issues the following 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.
General Electric Turbine Engines - CT7 Series
AD/CT7/10
Amdt 2
Propeller Gearbox(PGB) 7/2004
Applicability: General Electric Aircraft Engines (GEAE) CT7 series turboprop engines with propeller gearboxes (PGBs) identified by serial number (SN) in Table 1 of GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated 27 July 2001, and Table 1 of GEAE CT7 Turboprop Alert Service Bulletin (ASB) CT7-TP S/B 72-A0466 dated 17 April 2003. These engines are installed on, but not limited to, SAAB 340 series aeroplanes.
Requirement: 1. Inspect the propeller gearbox (PGB) oil filter impending bypass button (IBB) for extension. If PGB oil filter IBB is extended, replace the oil filter and carry out inspections in accordance with 3.A of the Accomplishment Instructions contained in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0453,dated 27 July 2001.
2. Replace left and right-hand idler gears in accordance with the Accomplishment Instructions GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452, dated 27 July 2001.
3. If the PGB is mated to a Hamilton Standard propeller and the left and right-hand idler gears have not been replaced in accordance with the Accomplishment Instructions contained in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452,dated 27 July 2001, replace the PGB.
Note: FAA AD 2004-07-09 Amdt 39-13553 refers.
Compliance: For Requirement 1: Unless previously accomplished, initial inspection within 50 hours time-in-service (TIS) after the effective date of this AD and thereafter on each day of aircraft operation until compliance with Requirment 2 or 3 of this Directive is achieved.
For Requirement 2: At next workshop visit of the PGB after the effective date of this AD.
For Requirement 3: Before accumulating an additional 2,000 engine flight hours after the 6 August 2003, the effective date of amendment 1 of this Directive.
This Amendment becomes effective on 8 July 2004.
General Electric Turbine Engines - CT7 Series
AD/CT7/10 Amdt 2 (continued)
Background: This AD is prompted by an on-going investigation that concluded that low-time PGB removals are due to accelerated wear of the PGB idler gears, rather than improperly hardened PGB input pinions. The actions specified in this AD are intended to prevent separation of the PGB left and right-hand idler gears, which could result in uncontained PGB failure and internal bulkhead damage, possibly prohibiting the auxiliary feathering system from fully feathering the propeller on certain PGB’s.
Amendment 1 clarified the applicability and, for administrative reasons, brought forward the effective date by one day.
This amendment includes additional PGB and PGB gears as detailed in the reference documents. There are no changes to the inspection requirements.
James Coyne
Delegate of the Civil Aviation Safety Authority 28 May 2004
The above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.
Overview
The Civil Aviation Safety Authority (CASA) has enacted the Airworthiness Directive AD/CT7/10 Amdt 2, effective 8 July 2004, to address safety concerns identified in General Electric Aircraft Engines (GEAE) CT7 series turboprop engines with propeller gearboxes (PGBs). This directive was introduced in response to an ongoing investigation that found low-time PGB removals were due to accelerated wear of the PGB idler gears, rather than improperly hardened PGB input pinions. The policy objective is to prevent separation of the PGB left and right-hand idler gears, which could result in uncontained PGB failure, internal bulkhead damage, and potentially prohibit the auxiliary feathering system from fully feathering the propeller on certain PGBs. CASA has revoked the previous AD AD/CT7/10 Amdt 1 and issued this amendment to clarify applicability and bring forward the effective date by one day, while also including additional PGB and PGB gears as detailed in the referenced documents. The directive requires specific actions such as inspecting and replacing the oil filter and idler gears, and, if applicable, replacing the PGB, in accordance with the instructions set out in the referenced service bulletins.
Scope and Application
The Airworthiness Directive (AD) AD/CT7/10 Amdt 2 applies to specific General Electric Aircraft Engines (GEAE) CT7 series turboprop engines with propeller gearboxes (PGBs) that are identified by serial numbers listed in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452 and Table 1 of GEAE CT7 Turboprop Alert Service Bulletin (ASB) CT7-TP S/B 72-A0466. These engines are predominantly installed on SAAB 340 series aeroplanes. The AD mandates specific actions to address the identified unsafe condition, including inspecting and, if necessary, replacing the propeller gearbox oil filter impending bypass button and idler gears, as well as the entire PGB under certain circumstances. Compliance with the directive involves conducting these actions within specified timeframes and conditions, such as within 50 hours time-in-service after the effective date of the AD, at the next workshop visit, or before accumulating additional engine flight hours. The AD extends across the Commonwealth of Australia and is enforced by the Civil Aviation Safety Authority (CASA) under its legislative powers as outlined in the Civil Aviation Safety Regulations 1998. This AD does not include any stated exclusions or exemptions but is subject to the broader regulatory framework of the CASR 1998, which may provide additional context or requirements through subordinate instruments.
Key Provisions
The Airworthiness Directive (AD) AD/CT7/10 Amdt 2, issued by the Civil Aviation Safety Authority (CASA) delegate, specifically addresses the maintenance of General Electric Aircraft Engines (GEAE) CT7 series turboprop engines installed on aircraft such as the SAAB 340 series. Section 1 (Applicability) specifies that the directive applies to certain CT7 series turboprop engines identified by serial numbers listed in GEAE CT7 Turboprop Service Bulletin CT7-TP S/B 72-0452 and CT7-TP ASB 72-A0466, dated 27 July 2001 and 17 April 2003 respectively. Section 2 (Requirement) outlines three main actions that must be taken to address potential safety concerns: the inspection of the propeller gearbox (PGB) oil filter impending bypass button (IBB) for extension and subsequent replacement if necessary, the replacement of left and right-hand idler gears, and the replacement of the PGB if it is mated to a Hamilton Standard propeller and the idler gears have not been replaced. These actions are detailed in the Accomplishment Instructions of the referenced service bulletins.
The obligations under this AD include conducting the specified inspections and replacements as per the defined timeframes. For Requirement 1, an initial inspection must occur within 50 hours of time-in-service after the directive's effective date and subsequently on each day of aircraft operation until compliance with Requirement 2 or 3 is achieved. Requirement 2 mandates the replacement of the left and right-hand idler gears at the next workshop visit of the PGB following the directive's effective date. Requirement 3 requires the replacement of the PGB before accumulating an additional 2,000 engine flight hours after the effective date of 6 August 2003. These obligations are designed to ensure that the specified maintenance actions are performed in a timely and effective manner to mitigate the risk of PGB failure.
Failure to comply with the AD may result in serious safety consequences, including uncontained PGB failure and internal bulkhead damage, which could prevent the auxiliary feathering system from fully feathering the propeller on certain PGBs. While the legislative instrument does not explicitly state civil or criminal penalties for non-compliance, non-compliance with CASA directives generally can lead to enforcement actions, including fines, suspension or revocation of certificates, and potential criminal charges in cases of severe non-compliance that result in accidents or significant safety breaches. The directive’s purpose is to ensure the airworthiness of affected aircraft by addressing specific safety issues related to the PGB and its components.