AD/CT7/13 - No. 3 Bearing

An Airworthiness Directive is a mandatory regulatory instrument issued by CASA under the Civil Aviation Act and associated regulations. It directs aircraft owners, operators, and maintainers to rectify a known unsafe condition. Non-compliance can render an aircraft unairworthy and expose the operator to enforcement action. The key aircraft component here is the No. 3 bearing, a part within the GE CT7-8A turboshaft engine that supports the rotor system and is subject to contamination by aluminium oxide. Aluminium oxide is a hard, abrasive particulate that can form in the engine’s front frame area, likely from the breakdown of aluminium components or from process residues. The AD’s background states that two bearing failures have been traced to this contamination; the directive’s purpose is to prevent further failures that could cause an in-flight engine shutdown. The term “cycles since new” means the number of operating cycles accumulated from the engine’s first entry into service. A cycle for a turboshaft engine is typically one start, one take-off power application, and one shut-down, but the AD does not define it; the GE maintenance manual would. Engines listed in Table 1 are 48 serial numbers, with the table showing some blank cells at the bottom, possibly indicating that those serial positions are not filled or that the table is incomplete. The AD does not explain the selection criteria for these serial numbers; presumably they fall within a certain production batch or time period associated with the contamination risk. The front frame is the engine’s forward structural housing; flushing it removes accumulated debris or contamination. The No. 3 bearing is a critical rotating component; replacement eliminates any existing contamination or wear. The prohibition on installing a bearing removed under this AD prevents the migration of a potentially contaminated or damaged part into another engine. The reference to FAA AD 2008-26-02 indicates that the United States Federal Aviation Administration issued a corresponding directive, and CASA has adopted it with possible modifications. The AD cites two technical documents: GEK 10517 (the shop manual) and Service Bulletin CT7-8 S/B 72-0017 Revision 02. These provide the detailed procedures, but the AD does not incorporate them by reference in the legal sense; rather, it requires compliance with the AD requirement, and the manuals serve as the approved means of compliance. The AD does not impose any reporting requirement, no record-keeping beyond the engine log entry, and no ongoing recurring inspection.

The primary duty bearers are the registered operators and owners of helicopters powered by GE CT7-8A turboshaft engines with any of the 48 serial numbers listed in Table 1. The AD notes that these engines are installed on - but not limited to - Sikorsky S92 helicopters. Therefore, any other aircraft type using that engine variant is also captured if it carries an affected serial number. The AD does not list aircraft registrations, so the operator must cross-reference engine serial numbers from the helicopter’s records against the table. The compliance cost falls on the operator or owner, who must bear the expense of removing the engine, performing the flush, procuring a new No. 3 bearing, and paying for labour. If the aircraft is on a lease or charter, the lessee or charterer may be contractually obligated, but the AD holds the registered operator ultimately responsible. Maintenance organisations that perform the work must be appropriately rated to work on CT7 engines; the AD does not mandate a particular repair station, only that the work follow the GE manual and service bulletin. The AD also indirectly affects General Electric as the engine manufacturer, as the directive relies on GE’s own service information. The prohibition on installing removed bearings affects parts suppliers and any entity that might otherwise refurbish and re-sell a used bearing. The AD is limited in scope: only those engines with specific serial numbers. All other CT7-8A operators are unaffected. That narrow scope means that the compliance burden is concentrated on a small number of operators, possibly those that acquired engines from a particular production run. For those operators, the compliance timeline of 6,200 cycles since new may be generous or tight depending on utilisation rates. A helicopter used for offshore oil and gas transport or emergency medical services may accumulate cycles quickly, requiring immediate grounding if the engine is near the threshold. The AD does not create any rights for third parties such as passengers or insurers, though the safety improvement (prevention of in-flight shutdown) indirectly benefits them. The CASA delegate who signed the AD (James Coyne) is the issuer, though the office itself is the enforcement authority.

The central duty is to comply with Requirement 1: for any engine with a serial number listed in Table 1, the operator must remove the engine from service, flush the front frame, and replace the No. 3 bearing within 6,200 cycles since new. That duty is absolute; the AD does not offer an alternative compliance timeframe, a waiver based on inspection, or a grace period beyond the 6,200 cycles. If the engine has already accumulated more than 6,200 cycles as of the effective date (9 April 2009), the duty becomes immediate: the engine must be removed before further flight. The operator has a right to rely on an engine log entry that shows the front frame was already flushed and the No. 3 bearing was replaced at some earlier point. If that log entry exists, no work is required. The AD does not specify who may make that log entry or what level of detail is required, but a competent person such as a licenced aircraft maintenance engineer would normally do so. The second duty (Requirement 2) prohibits installing any No. 3 bearing removed as detailed in Requirement 1. This prohibition applies after the effective date and is ongoing. It effectively mandates scrapping or quarantining the old bearing. The operator has no right to reinstall that bearing in any engine, regardless of condition. The AD does not expressly grant a right to apply for an alternative means of compliance (AMOC). However, under the broader regulatory framework (Civil Aviation Regulations 1988 or Civil Aviation Safety Regulations 1998, depending on which regime applies), operators may seek an AMOC from CASA. The AD itself does not list any exceptions. The operator also has the right to challenge the AD through judicial review or to seek a variation, but the AD text does not mention those avenues. The AD does not impose any record-keeping beyond the engine log entry; no separate report to CASA is required. It does not require the operator to notify CASA of compliance. The duty is to perform the physical action and to ensure the engine is not used unless compliant. Rights of the manufacturer or of other stakeholders are not addressed in the AD. The operator’s right to choose who performs the work is constrained only by the requirement to follow the GE manual and service bulletin; a licenced maintenance organisation would be expected to hold appropriate approvals.

The AD itself does not prescribe specific penalties, but non-compliance with an Airworthiness Directive is an offence under the Civil Aviation Act 1988 and the Civil Aviation Regulations. The maximum penalty can be substantial; for example, operating an aircraft that does not comply with an applicable airworthiness directive can attract civil penalties of hundreds of thousands of dollars for a body corporate, and criminal penalties including imprisonment for individuals in serious cases. The exact amounts depend on the specific regulation and any subsequent amendments, which are not detailed in the source. Enforcement is carried out by CASA, which has the power to issue infringement notices, seek civil penalty orders in the Federal Court, or refer matters for criminal prosecution. CASA may also suspend or cancel the aircraft’s certificate of airworthiness until compliance is demonstrated. The AD’s prohibition on installing removed bearings could also be enforced separately; any person who installs a bearing contrary to the AD may be liable. The AD creates strict liability in some jurisdictions: it is no defence that the operator did not know the engine serial number was on the list, though ignorance may affect the penalty. The practical risk for operators is that CASA may conduct surveillance or investigate after an incident; an unremedied AD would be a clear finding of non-compliance. The AD does not mention any right to cure or grace period after detection; each day of non-operation could constitute a separate offence. The 6,200 cycle limit is a hard threshold; if an operator exceeds it even by one cycle, they are in breach. The AD does not set out the criteria for CASA to grant an extension; that would be at CASA’s discretion under general regulations. There is no reference to any enforcement history for this specific AD in the source. Operators should also be aware that insurance policies may exclude cover if the aircraft is operated in non-compliance with an applicable AD, leaving the operator self-insured for any loss.

The AD operates within the framework of the Civil Aviation Act and regulations. It is a legislative instrument issued by a delegate of CASA, and it has the force of law. It interacts with the general airworthiness obligations under regulation 42 of the Civil Aviation Regulations 1988 or the equivalent in the Civil Aviation Safety Regulations 1998, which require the holder of an airworthiness certificate to ensure the aircraft is maintained in an airworthy condition. Compliance with an AD is a prerequisite for airworthiness. The AD also interacts with the regulatory regime for maintenance: the person who performs the flush and bearing replacement must be authorised under the appropriate maintenance organisation approvals or hold a licence with the relevant rating. The AD does not override other regulatory requirements; for instance, the installation of the new No. 3 bearing must also comply with any applicable airworthiness limitations in the engine’s type certificate data sheet. The AD specifically references the parallel FAA directive (2008-26-02 Amdt 39-15768). This indicates a system of bilateral recognition: CASA has adopted the FAA’s determination of an unsafe condition. In practice, if an operator holds both Australian and US registrations, compliance with the FAA AD may satisfy the CASA AD if the actions are equivalent, but the operator should confirm. The AD also references GE Aircraft Engines Service Bulletin CT7-8 S/B 72-0017, Revision 02, and the GE CT7-8 Shop Manual. These are proprietary documents; operators must have access to them. The AD does not incorporate them by reference in the legal sense (the full text is not reproduced), but compliance requires following those documents. The interaction with other ADs for the same engine type is not mentioned; if multiple ADs exist, each must be satisfied. The AD does not affect any contractual rights between operators and GE or between operators and their customers, though it may trigger force majeure clauses or require maintenance scheduling changes. There is no interaction with state or territory laws beyond general occupational health and safety for the maintenance work. The prohibition on installing a removed bearing may interact with trade practices laws if a supplier tried to sell the bearing as serviceable without disclosing the AD restriction, but that is indirect. The AD also does not mention any privacy or intellectual property issues.

The source document is AD/CT7/13, dated 26 February 2009, and it becomes effective on 9 April 2009. The AD itself does not indicate any prior amendments or earlier versions. The AD number is AD/CT7/13; the “13” suggests it is at least the thirteenth AD issued for this engine model, but that cannot be confirmed from the text. The document includes the notation “4/2009” in the heading, likely a CASA serial number for the year 2009. The source also references GE Aircraft Engines Service Bulletin No. CT7-8 S/B 72-0017, Revision 02, dated 14 May 2008, or earlier revision. That implies that the service bulletin has been revised, and the AD accepts the earlier revision as well. However, the AD itself is not shown as a revision of an earlier AD; it appears to be the original issuance. There is no mention of any superseded ADs, alternative compliance dates, or amendments. The FAA AD referenced (2008-26-02) was issued on 9 December 2008, so the CASA AD follows that by about three months. The CASA AD does not state that it supersedes any earlier CASA directive on the same subject. Without further CASA records, it is not possible to determine whether AD/CT7/13 has been amended, withdrawn, or superseded since 2009. The user provided only this single instrument; no subsequent amendments are in the source. For a practicing lawyer or operator, it would be essential to check the current version on the CASA website to see if this AD remains in force or has been replaced by a later directive, such as AD/CT7/20 or similar. The background investigation into two bearing failures is the stated trigger, but no amendment history is provided.

The source document makes no reference to any litigation. There is no mention of court cases, tribunal decisions, or administrative review proceedings related to this AD or to the underlying bearing failures. The AD itself is a straightforward corrective action with a clear factual background (two failures, contamination by aluminium oxide). It does not invite legal challenge on its face, though an operator could theoretically seek judicial review on grounds such as procedural error or unreasonableness. However, given that the AD is based on an FAA determination and issued under delegated authority, the likelihood of successful challenge is low. The absence of litigation history in the source does not guarantee that none has occurred; it simply means the text does not record any. Practitioners should conduct their own searches of Australian administrative law databases, particularly decisions of the Administrative Appeals Tribunal or the Federal Court, for any challenges to CASA ADs. Many ADs are accepted without litigation because the consequences of non-compliance (grounding, loss of licence) are severe, and the cost of compliance is often lower than the cost of litigation. The only potential litigation would be if an operator disputed the factual basis (e.g., that its engines were not within the affected serial number range or that the contamination theory was wrong). But the AD provides a safe harbour: if the engine log shows prior compliance, no further action is needed. That reduces the incentive to litigate. Also, the AD does not impose a financial penalty directly; it only requires work. An operator who believes the AD is unnecessary could apply for an AMOC rather than sue. No class actions or product liability claims are referenced, though one might imagine that the two original bearing failures could have given rise to claims against GE, but that is speculative and not in the source. The AD also does not mention any coronial inquest or accident investigation report; the background simply says “investigation for the root causes”. In summary, the source provides no litigation history for this specific AD.

Several aspects of this AD could trap an unwary operator or legal adviser. First, the applicability table includes blank cells at the bottom (rows with missing serial numbers). Those cells may indicate that no engine exists with those serial positions, or they may be typographical errors. An operator must check thoroughly; a blank cell does not mean the list is closed. The AD does not define “cycles since new”. For an engine that has been overhauled or had its cycle counter reset, it is unclear whether the AD refers to total cycles from new or cycles since last overhaul. Typically, “cycles since new” means from initial manufacture, but if an engine has undergone a major repair or replacement of the life-limited parts, the definition may change. The AD does not clarify. Second, the compliance threshold is 6,200 cycles since new, not 6,200 cycles from the effective date. An engine that is already at 6,200 cycles on 9 April 2009 must be removed immediately. There is no phase-in for engines near the limit. Third, the AD prohibits installing any No. 3 bearing removed as detailed in Requirement 1. It does not say “any No. 3 bearing removed under this AD” - it says “removed as detailed in Requirement 1”. If a bearing is removed for another reason (e.g., during an unrelated overhaul) but the engine is also on the list, is that bearing caught? The language could be read broadly: if the engine is on the list and the bearing is removed, the AD might deem that removal as being under Requirement 1, even if the operator intended a different purpose. That could lead to unintended scrapping of potentially serviceable bearings. Fourth, the AD does not require the operator to record compliance with CASA; only the engine log entry is mentioned. However, under other regulations, the operator may need to update the aircraft’s continuing airworthiness record and notify CASA if the aircraft is subject to an AD. Failure to do so could be an oversight. Fifth, the AD references “GE Aircraft Engines Service Bulletin No. CT7-8 S/B 72-0017, Revision 02, dated 14 May 2008, or earlier revision”. An earlier revision may contain different procedures. If an operator uses an earlier revision without checking that it is still acceptable, they might not fully comply. The AD says “or earlier revision”, so it permits using, say, Revision 01. But that older revision might not include all the necessary steps or might be superseded by Revision 02 for a reason. The AD does not warn about that. Sixth, the AD does not specify what constitutes a valid “flush”. The service bulletin likely details the procedure, but the AD itself is silent on how to verify that the flush was effective. Seventh, the AD applies to engines installed on any aircraft, not just the S92. An operator with a different helicopter type might overlook the AD if they do not track engine serial numbers diligently. Eighth, the AD is dated 2009; it may have been superseded or amended. Relying on this single document without checking current status could lead to compliance with an outdated requirement or missing a later mandate.

Compliance with AD/CT7/13 requires the operator to follow a sequence of steps, all grounded in the source text. Step one: identify the engine serial number(s) of each CT7-8A engine in the operator’s fleet. This should be cross-checked against the aircraft’s technical records. Step two: compare each serial number against Table 1 of the AD. Table 1 lists 48 specific serial numbers, though some cells are blank. If the engine’s serial number is not in the table, no further action is required for that engine under this AD. If the serial number is listed, proceed to step three. Step three: examine the engine log book. If the log records that the front frame was already flushed and the No. 3 bearing was replaced, then no further action is required. The AD does not require a minimum date for that record; any prior compliance suffices. However, the operator should confirm that the flush and replacement were performed in accordance with the GE service bulletin and shop manual, because the AD implicitly requires that level of quality. If the log does not show prior compliance, step four: determine the number of cycles-since-new for the engine. If the engine has accumulated 6,200 or more cycles since new as of the effective date (9 April 2009), the engine must be removed from service immediately and not flown again until the corrective actions are completed. If the engine has fewer than 6,200 cycles, it must be removed from service before it reaches 6,200 cycles. Step five: arrange for the engine to be removed and transported to an approved maintenance organisation. Step six: have the maintenance organisation perform the flush of the front frame in accordance with GE Aircraft Engines Service Bulletin CT7-8 S/B 72-0017 Revision 02 (or an earlier revision) and replace the No. 3 bearing in accordance with the GE CT7-8 Shop Manual GEK 10517. Step seven: ensure that the removed No. 3 bearing is not installed in any other engine. The operator should either scrap the bearing or clearly mark it as non-serviceable and quarantine it. Step eight: update the engine log book to record the flush and replacement. Include the engine serial number, the date, the cycles at which compliance occurred, the manuals used, and the signatures of the certifying staff. The log entry serves as the proof of compliance for future audits or lease inspections. Step nine: maintain a copy of the AD and the log entry in the aircraft’s continuing airworthiness record system. Step ten: if the operator wishes to use an alternative method of compliance (e.g., a different flush procedure or a later cycle limit), they must apply to CASA for an Alternative Means of Compliance (AMOC) before the deadline. The AD does not mention AMOC, so the operator should refer to the relevant regulation (likely CAR 39 or CASR Part 39). Step eleven: for engines that were already compliant before the AD, no further action is needed, but the operator should retain the log evidence. Step twelve: if the operator plans to sell or transfer the engine, ensure the log reflects the AD compliance status, as any future purchaser will rely on that. The costs include the direct labour and parts, the potential grounding of the aircraft for the duration of the maintenance, and the administrative cost of tracking cycles. The operator should also consider that the AD may trigger an earlier-than-planned overhaul if the engine is near the cycle limit, disrupting maintenance schedules.