AD/TAY/8 Amdt 2 - Engine LP Fuel Tube

The central concept is an airworthiness directive issued under Part 39 of the Civil Aviation Safety Regulations 1998 (CASR). An AD is a mandatory regulatory instrument that requires the aircraft owner or operator to inspect, modify, repair, or replace a component within a specified timeframe, or before further flight, to correct an unsafe condition. AD/TAY/8 Amdt 2 follows the standard structure: applicability, requirement, compliance times, terminating action, effective date, and background. The directive is binding: non-compliance makes the aircraft unairworthy under the Civil Aviation Act and invalidates the aircraft's certificate of airworthiness.

A key mechanical concept is terminating action. The directive provides that replacement of both old fuel tube part numbers (JR33021 and JR26955) with the new improved tube (JR58112) terminates any further repeat inspections. This is a conventional AD design: rather than requiring indefinite periodic inspections, the directive incentivises a permanent fix by allowing operators to escape the ongoing inspection burden once the improved part is installed. The terminating action reference in the source cites Service Bulletin TAY-73-1592R1 dated 30 April 2003, suggesting that the replacement solution has been available since at least 2003, but the mandatory requirement to use it was imposed through successive amendments.

Another important concept is the distinction between time-since-new (TSN) and time-in-service (TIS). TSN refers to the total accumulated operating hours on the engine from its manufacture, while TIS tracks the hours accumulated since a specific event (such as the last inspection). The directive uses TSN to define the initial compliance deadline for relatively new engines (less than 4,000 hours TSN on the effective date or on 30 December 2005) and TIS to define the repeat inspection intervals (1,000 hours since last inspection). Operators must maintain accurate records of both metrics to determine exactly when each step is due.

The source also introduces the concept of approved data through reference to Rolls Royce Service Bulletins. The directive does not reproduce the inspection and replacement procedures; it requires compliance with the Accomplishment Instructions in the specified bulletins. Those bulletins are incorporated by reference and become legally binding. Operators must hold current copies of TAY-73-1553R3 (or TAY-73-1593R1), TAY-73-1669, and TAY-73-1592R1. Use of obsolete revisions (e.g., using an earlier version of TAY-73-1592) would not satisfy the directive.

The directive also reflects the concept of harmonisation with foreign airworthiness requirements. It notes that German LBA AD D-2002-358/6 (approved by EASA approval number 2005-4734 dated 31 May 2005) addresses the same unsafe condition. This is significant for operators with engines registered in multiple jurisdictions or maintained under Part 145 approvals that rely on foreign type certificate data sheets. Compliance with the foreign AD alone may not satisfy CASA's directive unless it is substantively identical, which it largely is given the cross-references.

The grac period for replacement illustrates a deliberate regulatory trade-off. The original AD (effective 16 July 2003) and Amendment 1 (effective 8 July 2004) required replacement by 30 June 2005. Amendment 2 extends that to 31 December 2005, and adds a further deferral for engines with less than 4,000 hours TSN on that date. This suggests either that the supply of improved tubes was constrained, or that CASA accepted that immediate grounding of large numbers of engines was disproportionate to the risk. The reduced inspection interval from 2,000 to 1,000 hours increases the short-term compliance burden but allows operators more time to schedule the replacement.

The directive directly affects any person or organisation responsible for the continuing airworthiness of aircraft fitted with Rolls Royce Tay series engines that fall within the specified model list: TAY 611-8, 620-15, 650-15 and 651-54. These engines are commonly installed on business jets (such as the Gulfstream IV series and the Fokker 100/70 regional airliner) and some military derivative aircraft. The effects cascade through several layers of responsibility.

Aircraft owners bear the ultimate financial liability for compliance. They must bear the cost of procuring the improved low pressure fuel tube (P/N JR58112) and paying for the labour to perform the inspections and replacement. They also bear the cost of lost revenue during downtime. If an owner leases the aircraft to a third-party operator, the lease agreement likely allocates compliance responsibility, but the regulatory duty attaches to the registered operator (the holder of the certificate of airworthiness). For aircraft operated under air operator certificates (AOCs), the AOC holder must ensure that all ADs affecting its fleet are complied with as a condition of its approval.

Maintenance organisations (whether Part 145 approved or under a maintenance control manual) must have access to the correct Rolls Royce Service Bulletins and must apply the Accomplishment Instructions precisely. They must also correctly interpret the compliance times, distinguishing between engines with less than or more than 4,000 hours TSN, and between the two engine groups (620-15/650-15 versus 611-8/651-54). Mistakes in applying the grace period could result in an aircraft being operated in a non-compliant state if the maintenance organisation fails to schedule the inspection within the required flight hours.

Parts suppliers and engine overhaul shops are affected indirectly. The improved tube P/N JR58112 must be available in the supply chain. If there is a shortage, operators may struggle to meet the 30 December 2005 deadline, exposing them to grounding risk. The directive does not provide for alternative parts; only the specified part number is acceptable.

Regulatory staff at CASA have a continuing role: they may need to issue further ADs if the terminating action proves insufficient, or if the improved part itself develops issues. They also handle requests for alternative means of compliance (AMOCs) if an operator cannot comply in the prescribed manner, although no such provision is explicit in this directive.

Insurers and lessors may rely on AD compliance as a contractual condition. An engine that is not AD-compliant may be deemed unairworthy, triggering insurance exclusions or breach of lease covenants. The presence of multiple AD amendments (original, Amdt 1, Amdt 2) creates a compliance trail that must be documented carefully to satisfy due diligence inquiries.

In economic terms, the directive imposes concentrated costs on a relatively small fleet of specialised aircraft engines. The benefits (reduced risk of in-flight flame-out due to fuel starvation) are diffuse but significant. The compliance burden falls disproportionately on operators with high-utilisation aircraft, because the 1,000-hour TIS interval triggers repeat inspections more frequently for such aircraft. Conversely, low-utilisation aircraft may face the replacement deadline (30 December 2005) before they hit 4,000 hours TSN, forcing a mandated replacement earlier than the risk profile might otherwise justify.

The directive imposes specific, non-delegable duties on the registered operator or the person responsible for continuing airworthiness. The primary duty is to perform each of the five enumerated requirements within the prescribed compliance times. This is not a recommended practice; it is a mandatory condition for maintaining the aircraft as airworthy.

The key duties are:

1. Duty to inspect P/N JR33021 for fretting - using the correct Service Bulletin. For TAY 620-15 and 650-15 engines, this must occur before further flight after the effective date (4 August 2005). For TAY 611-8 and 651-54 engines with more than 4,000 hours TSN, also before further flight. For engines with less than 4,000 hours TSN, inspection is due before reaching 4,000 hours TSN.

2. Duty to repeat the JR33021 inspection - at intervals not exceeding 1,000 hours TIS from the last such inspection.

3. Duty to inspect P/N JR26955 - within 1,000 flight hours after the effective date, using SB TAY-73-1669.

4. Duty to repeat the JR26955 inspection - at intervals not exceeding 1,000 hours TIS from the last such inspection.

5. Duty to replace both tubes with P/N JR58112 - by 30 December 2005, unless the engine has less than 4,000 hours TSN on that date, in which case replacement is due before reaching 4,000 hours TSN. The replacement must follow SB TAY-73-1592R1.

6. Duty to maintain records - the operator must retain evidence of compliance, including certification that the inspection or replacement was performed in accordance with the specified bulletins. This is implicit from the requirement that maintenance records must certify compliance.

The directive also creates a right to terminate repeat inspections by performing the terminating action (replacement). Once replacement is completed, the operator is no longer required to perform the 1,000-hour repeat inspections for JR33021 or JR26955. This is a valuable right because it converts a recurring compliance obligation into a one-time capital expenditure. Operators who delay replacement bear the burden of ongoing inspections, which themselves carry cost and risk of findings.

Another important right is the ability to rely on prior compliance with earlier versions of the AD or with the foreign LBA AD. The first sentence of the Requirement states that unless maintenance records certify compliance with cancelled AD/F100/57, AD/TAY/8, AD/TAY/8 Amdt 1, German LBA AD 2002-331 or 2002-358/2 (or the SBs referenced in those LBA ADs), the inspections must be performed. This creates a grandfathering mechanism: an operator who already complied with an earlier AD through action under the LBA AD does not need to reperform the initial inspection under this amendment, provided the records are adequate. However, the repeat inspections and replacement still apply if not already done.

The directive does not confer a right to delay compliance on grounds of cost, parts unavailability, or operational inconvenience. The enforcement regime treats non-compliance as a breach of the airworthiness regulations. The only formal avenue for seeking relief is an application for an alternative means of compliance (AMOC) under CASR Part 39. No explicit AMOC pathway is mentioned in this AD, but it is available by operation of law. Operators in genuine supply difficulty may approach CASA for an extension or an alternative method.

Non-compliance with AD/TAY/8 Amdt 2 triggers enforcement under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998 (CASR). The Airworthiness Directive itself does not specify penalties, but the legislative framework does. Failure to comply with an AD renders the aircraft unairworthy. Operating or permitting the operation of an unairworthy aircraft is an offence under regulation 42 of CASR, carrying a maximum penalty of 50 penalty units for an individual (currently $9,250, though the figure in 2005 would be lower) and 250 penalty units for a body corporate (approximately $46,250 at 2005 rates, depending on the penalty unit value). The court also has power to impose additional remediation orders.

Beyond financial penalties, the practical enforcement tool is grounding. CASA can issue a direction under subsection 20BA of the Civil Aviation Act directing the operator not to operate the aircraft until the non-compliance is rectified. This is typically the immediate consequence of an AD non-compliance discovered during a ramp check or airworthiness review. The aircraft's certificate of airworthiness may be suspended or cancelled, and the aircraft cannot fly until the defect is corrected and a release to service is issued.

CASA also has powers under Part 39 of CASR to take action. Regulation 39.023 provides that a person commits an offence if they operate an aircraft to which an AD applies without complying with the AD. The penalty is 50 penalty units. The same regulation applies to the operator and the pilot in command, so both entities may be liable.

Enforcement can also be indirect. For operators holding an air operator certificate (AOC), non-compliance with an AD may result in a finding under the operator's safety management system, leading to increased surveillance, suspension of the AOC, or denial of renewal. For maintenance organisations, performing work that does not comply with an AD can constitute a breach of maintenance regulations and may attract suspension of the organisation's Part 145 approval.

The directorate may also refer non-compliance to the Director of Public Prosecutions for criminal proceedings if there is evidence of reckless disregard or intentional falsification of maintenance records. The background of this AD refers to an in-flight double engine flame-out caused by a fuel leak from a partial disconnect. If a similar incident occurred on an aircraft that had not complied with the AD, the operator and maintenance personnel could face criminal charges under the aviation safety provisions of the Criminal Code (Cth) for endangering the safety of an aircraft.

From a free-market perspective, the enforcement regime is strict and leaves little room for cost-benefit analysis by the operator. The AD imposes a uniform solution regardless of individual usage patterns, maintenance history, or risk appetite. An operator who has never experienced a fuel leak and who believes the improved tube is not necessary for its specific fleet cannot opt out. The only flexibility is through the grace periods built into the compliance times. The enforcement mechanisms ensure that the state's safety assessment overrides private judgment, which is characteristic of prescriptive aviation regulation.

AD/TAY/8 Amdt 2 operates within a larger legal framework that includes domestic regulations, foreign airworthiness requirements, and contractual arrangements.

Domestic framework: The directive is issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998, specifically Part 39 (Airworthiness Directives). Part 39 incorporates ADs into the Australian regulatory scheme and gives them the force of law. The directive explicitly cancels AD/F100/57, which was the earlier AD addressing the same unsafe condition on the Tay 650 fleet. This cancellation streamlines the compliance record: operators who held compliance data under AD/F100/57 now need to ensure that their records align with the new requirements. AD/TAY/8 and its amendments replace the earlier directive entirely.

Interaction with foreign airworthiness requirements: The directive cross-references German LBA AD D-2002-358/6 (as approved by EASA approval number 2005-4734 dated 31 May 2005). This is significant because many Tay engines are type-certificated in Germany (the TAY is certified by the LBA as part of the engine's European type certificate). Operators who maintain aircraft to EASA standards may have already complied with the LBA AD. The directive recognises prior compliance with the LBA AD (or the bulletins referenced in it) as satisfying the initial inspection requirement. However, it does not automatically accept the LBA AD's compliance times for the repeat inspections and replacement. An operator who complied with the LBA AD should check that the maintenance records certify compliance in terms that match the CASA directive's requirements. The effective date for the CASA directive is 4 August 2005, while the EASA approval of the LBA AD is dated 31 May 2005. There is a gap of about two months during which an operator could have complied with the EASA-approved AD but still need to comply with the CASA AD separately if the aircraft is registered in Australia.

Interaction with manufacturer's service bulletins: The directive incorporates by reference three Rolls Royce Service Bulletins. The bulletins themselves are not law; they become mandatory only because the AD requires compliance with their Accomplishment Instructions. An operator who uses an earlier revision of the bulletins (e.g., TAY-73-1592 dated 30 April 2003 instead of the May 2005 revision) would not be in compliance. The directive specifies the exact revision numbers and dates. This raises a practical interaction: if Rolls Royce later issues a later revision of the bulletin, the operator cannot use it unless CASA amends the AD or issues an AMOC. The bulletins are incorporated as at a fixed point in time.

Interaction with airworthiness reviews and maintenance schedules: AD compliance is checked during the annual airworthiness review under CASR Part 43. The reviewer must verify that all applicable ADs are complied with and recorded. If an operator has not terminated the inspections or replaced the tubes by the deadline, the airworthiness review will not be passed. Similarly, the aircraft's maintenance schedule must incorporate the 1,000-hour repeat inspections as recurring items.

Interaction with sale or lease contracts: A prospective purchaser of a Tay-powered aircraft will conduct an AD compliance audit. Missing compliance with an AD like this one can reduce the aircraft's value or require the seller to indemnify the buyer. The presence of multiple amendments means a thorough compliance history is essential.

Interaction with other airworthiness directives: This AD applies only to the low pressure fuel tube. Other ADs may apply to the same engine models (e.g., for the high pressure fuel tube, gearbox, turbine blades). Operators must maintain a comprehensive AD status record, not rely solely on this document.

AD/TAY/8 has undergone three iterations since its initial issue. The source document is Amendment 2, dated 24 June 2005 and effective 4 August 2005.

Original issue - AD/TAY/8 became effective 16 July 2003. It cancelled AD/F100/57 (which applied only to the Tay 650 fleet) and extended applicability to other Tay series engines (TAY 611-8, 620-15, 650-15, 651-54). The original AD required inspection of low pressure fuel tube P/N JR33021 for fretting, with a repeat inspection interval of 2,000 hours TIS. Replacement of the tube with P/N JR58112 was required by 30 June 2005. The terminating action provision referenced SB TAY-73-1592R1 dated 30 April 2003.

Amendment 1 - Became effective 8 July 2004. The source does not reproduce the full text of Amendment 1, but describes it as adding an additional fuel tube that is required to be replaced. Based on the Amendment 2 text, that additional tube appears to be P/N JR26955. However, Amendment 1 did not include an inspection requirement for JR26955; it only required replacement. The compliance times for inspection and replacement did not change. Amendment 1 also confirmed the replacement deadline of 30 June 2005.

Amendment 2 (this directive) - Effective 4 August 2005. The key changes from Amendment 1 are:

1. Inspection requirement added for P/N JR26955 - Requirement 3 requires inspection within 1,000 flight hours after the effective date, and Requirement 4 requires repeat inspections at 1,000-hour intervals. Previously, only P/N JR33021 required inspection.

2. Repeat inspection interval reduced - from 2,000 hours TIS to 1,000 hours TIS. This applies to both JR33021 inspections.

3. Replacement deadline extended - from 30 June 2005 to 31 December 2005. The extension is only for the final replacement; the initial inspections and repeat inspections have shorter deadlines.

4. Grace period for low-time engines - engines with less than 4,000 hours TSN on 30 December 2005 may delay replacement until reaching 4,000 hours TSN. This grace did not appear in the original or Amendment 1.

5. Service Bulletin revisions updated - the bulletins referenced now include the 31 May 2005 revisions (TAY-73-1553R3, TAY-73-1593R1, TAY-73-1669, TAY-73-1592R1). The terminating action still references the 30 April 2003 revision of TAY-73-1592, which is consistent with the earlier version.

The amendment history reveals a regulatory learning process. The original AD focused on the fuel leak from JR33021. In-service experience apparently revealed that JR26955 also needed attention, first through replacement (Amdt 1) and later through inspection (Amdt 2). The reduction of the repeat inspection interval suggests that the 2,000-hour period was considered insufficient to detect fretting before failure. The extension of the replacement deadline and addition of the low-time grace period likely reflect supply chain constraints or recognition that grounding a large number of engines by 30 June 2005 would cause disproportionate disruption. The net effect is a more stringent inspection regime but more flexible replacement timing.

The source does not mention any litigation associated with AD/TAY/8 or its predecessors. No court cases are cited. This is typical for airworthiness directives: they are issued under delegated powers and are rarely challenged in court. Operators who disagree with the technical basis of an AD may make representations during the consultation period (if the AD is proposed) or apply for an AMOC, but legal challenges are uncommon because the cost of delay and the risk of grounding usually outweigh the benefit of disputing the directive.

However, it is possible that the underlying unsafe condition (fuel leakage leading to double engine flame-out) gave rise to civil litigation between the aircraft owner and the engine manufacturer, or between the operator and third parties, though no such cases appear in the public record connected to this specific AD. The AD's background describes an in-flight double engine flame-out that motivated AD/F100/57. That incident could have generated lawsuits in the United States (where the aircraft type is common) or in the European Union, but no information is provided.

In Australia, AD non-compliance can become an issue in criminal prosecutions under the Civil Aviation Act if an accident occurs and non-compliance is discovered. For example, in the investigation of an engine failure or fuel leak incident, investigators would check AD compliance records. If the AD was not complied with, the operator or maintainer could face charges under section 20A of the Civil Aviation Act (operating an aircraft in a manner dangerous to safety) or under the Criminal Code. No such known prosecution relates to this AD.

The practical significance of the absence of litigation is that the AD's requirements have been accepted as technically justified by the industry. Operators have complied rather than litigating. The amendments show that CASA adjusted compliance times and added inspection requirements in response to feedback, which may have forestalled formal disputes. The directive itself provides a termination option (replacement) that reduces the long-term compliance burden, which also mitigates resistance.

For the purposes of this deep dive, the litigation history heading confirms that no court has tested the validity or interpretation of this AD. The legal risks are therefore limited to enforcement action for non-compliance, not to challenges by operators against the AD.

Several traps in AD/TAY/8 Amdt 2 can catch out even experienced maintenance planners.

Trapping the grace period for low-time engines. For TAY 611-8 and 651-54 engines with less than 4,000 hours TSN on the effective date (4 August 2005), the initial inspection of JR33021 is not required before further flight; it is required before reaching 4,000 hours TSN. However, for TAY 620-15 and 650-15 engines, the initial inspection is required before further flight regardless of TSN. Do not assume the grace period applies to all models. The language for the 620/650 series has no TSN escape. An operator with a 620 engine that had 500 hours TSN on 5 August 2005 would need to inspect before dispatch that day.

Mixing up TIS and TSN. The repeat inspection interval uses TIS (time since last inspection), while the replacement grace uses TSN (time since new). An operator who resets the TIS clock after each inspection must not confuse TSN with TIS when determining when replacement is due. If an engine reaches 3,500 hours TSN on 1 November 2005, but has high daily utilisation, it might cross 4,000 hours TSN before 30 December 2005, triggering an earlier replacement obligation than the calendar deadline suggests.

Double inspection burden for JR26955. Requirement 3 (inspect JR26955) applies to all engines within 1,000 flight hours of the effective date. But if the engine has already been replaced with JR58112 under the terminating action, the JR26955 inspection is not needed because it is no longer installed. However, if the operator has only replaced JR33021 but not JR26955 (which would not be possible under the terminating action, as both must be replaced together), the separate inspection of JR26955 remains live.

SB revision control. The directive specifies exact revision numbers and dates for the Rolls Royce Service Bulletins. Using an earlier revision could invalidate the compliance. For example, the terminating action references SB TAY-73-1592R1 dated 30 April 2003 as the acceptable basis for terminating action. But the replacement requirement references SB TAY-73-1592R1 dated 31 May 2005. The terminating action will accept either revision? The text is ambiguous: the terminating action paragraph says replacement in accordance with SB TAY-73-1592R1 dated 30 April 2003 terminates further inspections. The replacement requirement (Requirement 5) says to replace in accordance with SB TAY-73-1592R1 dated 31 May 2005. In practice, the May 2005 revision supersedes the April 2003 revision, so using the later one is safe. But an operator who still has the April 2003 revision and uses it might argue they are complying with the terminating action, but not with Requirement 5. The safest course is to use the May 2005 revision for all actions under this amendment.

The cancelled AD/F100/57 trap. The directive says the initial inspection is not required if maintenance records certify compliance in accordance with cancelled AD/F100/57. But AD/F100/57 is cancelled. An operator who holds a compliance certificate referencing AD/F100/57 should verify that the compliance it achieved is fully equivalent to the initial inspection under this AD. The fuel tube populations may differ (F100/57 applied only to Tay 650, not 611-8). If the operator has a Tay 611-8 engine with a compliance record under AD/F100/57 that is plainly inapplicable, the records may be misleading.

Terminating action not retroactive. If replacement was performed before the effective date of this amendment, does it satisfy the requirement? The terminating action paragraph references SB TAY-73-1592R1 dated 30 April 2003. If an operator replaced both tubes in 2004 using that bulletin, they have already completed the terminating action. The 1,000-hour repeat inspections are not required. However, the operator must still have records proving that the replacement was done correctly. The requirement to inspect JR26955 (introduced by this amendment) may not apply if the tube was already replaced with JR58112 before the effective date. So prior replacement is advantageous.

The effective date gap. The directive is dated 24 June 2005 but becomes effective on 4 August 2005. Operators have about six weeks to prepare. For TAY 620-15 and 650-15 engines, Requirement 1 (inspect JR33021) is due "prior to further flight after the effective date" meaning the first flight after 4 August 2005 must not occur unless the inspection has been done. That is an immediate grounding requirement. Operators must ensure the inspection is scheduled before the aircraft flies on or after 4 August.

Compliance with AD/TAY/8 Amdt 2 requires a methodical approach using the directive, the Rolls Royce Service Bulletins, and accurate engine records. The steps below assume the operator has not already performed replacement.

Step 1: Identify applicable engines. Confirm that each engine model is one of TAY 611-8, 620-15, 650-15, or 651-54. Check the engine nameplate or type certificate data sheet. If the engine is a derivative not listed, apply for an AMOC if needed.

Step 2: Retrieve the correct Service Bulletins. Obtain Rolls Royce TAY-73-1553R3 (or TAY-73-1593R1), TAY-73-1669, and TAY-73-1592R1, all dated 31 May 2005. Ensure the maintenance organisation has these on hand. Do not rely on earlier revisions except for prior terminating action under the April 2003 revision.

Step 3: Assess current compliance status. Review maintenance records to see if any of the following have been done:

• Compliance with cancelled AD/F100/57, AD/TAY/8 (original), AD/TAY/8 Amdt 1, German LBA AD 2002-331 or 2002-358/2.
• Replacement of both P/N JR33021 and P/N JR26955 with P/N JR58112, per SB TAY-73-1592R1 (either revision).
• Inspection of P/N JR33021 per earlier SB. If terminating action (replacement) is already recorded, no further action is needed. If only partial compliance exists (e.g., JR33021 replaced but not JR26955), the termination is not achieved; both tubes must be replaced.

Step 4: Determine initial inspection timing. For each engine:

• TAY 620-15 or 650-15: perform initial inspection of JR33021 before further flight after 4 August 2005.
• TAY 611-8 or 651-54: if TSN is 4,000 or more, perform before further flight after 4 August 2005. If TSN is less than 4,000, schedule the inspection before the engine reaches 4,000 hours TSN. Perform the inspection per the Accomplishment Instructions of TAY-73-1553R3 or TAY-73-1593R1. Record the findings. If fretting is found, the tube must be replaced earlier than the 30 December 2005 deadline? The directive does not explicitly require immediate replacement upon finding fretting during inspection, but the presence of fretting is an unsafe condition that likely requires rectification before further flight under normal maintenance rules. Better practice: replace immediately if fretting is found.

Step 5: Perform JR26955 inspection. Within 1,000 flight hours after 4 August 2005, inspect P/N JR26955 per SB TAY-73-1669. This deadline is separate from the JR33021 schedule.

Step 6: Plan repeat inspections. Both inspections must repeat at intervals not exceeding 1,000 hours TIS since the last inspection. Enter these as recurring tasks in the maintenance schedule. The TIS clock starts from the date the last inspection was performed. For high-utilisation aircraft, a 1,000-hour interval may be less than one year. Track cumulative flight hours.

Step 7: Procure and replace. Order P/N JR58112. The replacement deadline is 30 December 2005, unless the engine has less than 4,000 hours TSN on that date, in which case replacement is required before reaching 4,000 hours TSN. Note that the grace period applies only to the replacement deadline, not to the inspection intervals. When performing replacement, use SB TAY-73-1592R1 (May 2005 revision). Ensure both old tubes are removed and replaced. Record the part number and serial number of the new tube.

Step 8: Record termination. Once replacement is complete, the repeat inspection requirements cease. The maintenance records should clearly state that terminating action per AD/TAY/8 Amdt 2 has been accomplished. No further inspections for these tubes are required.

Step 9: Maintain records. All inspection and replacement actions must be recorded in the engine logbook or aircraft maintenance records. The record should include the AD number, the requirement number, the Service Bulletin used, the date, TIS and TSN at the time, any findings, and the certifying engineer's details. These records are needed for airworthiness reviews and for any subsequent sale or lease.

Step 10: Review for other applicable ADs. This AD is only one. Ensure the fleet's AD status is managed using a competent tracking system that accounts for all ADs, including those on the same part numbers from other regulatory authorities.

If compliance proves impracticable due to parts shortage, an alternative means of compliance (AMOC) should be sought from CASA. The AMOC must demonstrate an equivalent level of safety. Given the directive's background of a double flame-out incident, CASA is unlikely to grant an AMOC that delays replacement significantly without compelling evidence.