AD/CON/84 Amdt 3 - Starter Adapter Assembly

The AD introduces several technical concepts that are central to understanding its operation.

Starter adapter assembly. This is the component that connects the starter motor to the engine’s crankshaft gear. According to the background, failures of this assembly have been associated with six service difficulty reports and one fatal accident. The directive treats the starter adapter as a separate tracked component with its own time-in-service intervals for inspection (400 hours TIS plus or minus 10 hours), distinct from the main engine inspection cycles.

Rough running. This is a specific condition defined in the AD as a sudden increase in perceived vibration levels that cannot be cleared by adjusting engine controls, particularly the fuel mixture setting. It is not a general vibration complaint; it must be sudden and not correctable by normal control adjustments. The AD provides cross-references to the aircraft manufacturer’s Airplane Flight Manual, Pilot’s Operating Handbook or Aircraft Owners Manual for further information. Importantly, rough running triggers an immediate grounding requirement (before further flight), and special flight permits are expressly prohibited for engines in this condition. This is a significant operational restriction.

Time in service (TIS). This is the standard aviation measure of cumulative operating hours since the component was new or last overhauled. The AD uses TIS for all compliance deadlines, either in absolute hours (e.g., 100 hours, 400 hours) or as a trigger for first inspection (e.g., 25 hours TIS after effective date). It also allows a tolerance of plus or minus 10 hours on recurring intervals, which provides some scheduling flexibility.

Mandatory Service Bulletin MSB94-4G. This is the TCM document that contains the detailed inspection, replacement and installation procedures referenced by the AD. The AD specifically requires the revision dated 31 October 2005, or later FAA-approved revisions. The bulletin is divided into parts: Part 1, Part 2, Part 3 and Part 4 (installation of bushing), and Part 5 (installation of service kit). The AD does not reproduce these procedures; it mandates compliance with them as if they were part of the directive itself.

Service kit P/N EQ6642 (new) or EQ6642R (rebuilt). This is the replacement part that must be installed at the next engine overhaul or starter adapter replacement. The AD explicitly states that installing this kit does not constitute terminating action for the recurring inspections required by other paragraphs. Therefore, even after the kit is fitted, the 100-hour (or 400-hour) inspection cycle continues.

Needle bearing P/N 537721 and bushing P/N 654472. The AD mandates that if the needle bearing (P/N 537721) is found installed in the crankcase during any inspection, it must be replaced with a bushing (P/N 654472) or an equivalent approved bearing. This is a one-time replacement (if found) and is linked to the Part 4 installation procedure in the bulletin.

Special flight permit prohibition. The AD explicitly states that special flight permits are prohibited for rough-running engines described in the AD. This means an aircraft with a rough-running engine cannot be flown to a maintenance facility under a ferry permit; it must be repaired in place before any further flight. This is a harsh but legally clear constraint.

FAA AD 2007-05-15. The Australian AD notes that it refers to the corresponding FAA airworthiness directive (AD 2007-05-15 Amendment 39-14976 dated 12 March 2007). This is the US equivalent directive, which the CASA AD is aligning with, likely to maintain bilateral airworthiness recognition.

The AD directly affects any person or organisation who owns, operates or maintains an aircraft powered by a Teledyne Continental Motors GTSIO-520 series reciprocating engine. The AD lists several aircraft types known to use these engines: Twin Commander (formerly Aero Commander) model 685, Cessna models 404, 411 series and 421 series, British Aerospace (Scottish Division) model B.206 series 2, and Aeronautica Macchi model AM-3. However, the applicability note says these engines are installed on, but not limited to, those models. Therefore any aircraft with a GTSIO-520 engine, regardless of make, is subject to the AD. This includes helicopters that might use the engine, though the listed models are all fixed-wing.

Aircraft owners bear the ultimate responsibility for compliance, which includes ensuring the required inspections and replacements are carried out within the prescribed time limits. For operators of commercial aircraft (e.g., charter operations, aerial work), the AD imposes operational constraints: an aircraft with a rough running engine cannot be flown under a special flight permit, and the 100-hour inspection cycle may cause downtime that disrupts revenue service.

Maintenance organisations, including repair stations and the licensed aircraft maintenance engineers (LAME) that perform the work, must have access to the TCM Mandatory Service Bulletin MSB94-4G (or later FAA approved revision) and must be able to source the specified parts: service kit EQ6642 or EQ6642R, and bushing P/N 654472 (or equivalent bearing). They must also be capable of performing the needle bearing replacement if found.

Parts suppliers are affected because the AD may increase demand for the starter adapter service kit and bushing. However, the AD does not require replacement of entire assemblies; only inspections and targeted component replacements.

Aircraft insurers may take the AD into account when underwriting risk. Non-compliance could be a factor in claims, particularly if a failure occurs that the AD was designed to prevent.

The AD also indirectly affects aircraft buyers and sellers. An aircraft cannot be sold as compliant if the AD actions are not up to date. The recurring nature of the inspections (every 100 hours or 400 hours) creates an ongoing maintenance liability that should be reflected in valuation.

Because the AD is issued by CASA, it applies to Australian-registered aircraft wherever they fly. It may also apply to foreign-registered aircraft operating in Australia if the AD is adopted by reference or enforced through bilateral agreements.

The AD imposes specific duties on the responsible person (typically the aircraft owner or operator) and confers certain rights regarding compliance.

Duty to inspect. For any GTSIO-520 engine, the responsible person must ensure that the inspection procedures in Parts 1, 2 and 3 of TCM MSB94-4G are performed at the prescribed intervals. This is not a one-time action; the inspections repeat at each 100-hour TIS or annual inspection, whichever comes first, with the plus or minus 10-hour tolerance.

Duty to replace and install. If during those inspections any component fails the specified criteria, it must be replaced. Additionally, if a needle bearing P/N 537721 is found in the crankcase, it must be replaced with bushing P/N 654472. And the service kit EQ6642 (new) or EQ6642R (rebuilt) must be installed at the next engine overhaul or starter adapter replacement.

Duty to ground rough running aircraft. Upon observing rough running as defined, the aircraft cannot be flown again until the inspections described in requirement 1 (Parts 1 and 3) are performed and necessary replacements are made. Special flight permits are prohibited, so there is no legal way to ferry the aircraft to a maintenance base. The only option is maintenance at the current location. This duty runs to the pilot in command as well as the owner.

Duty to track TIS accurately. Compliance deadlines depend on accurate time-in-service records for the engine and for the starter adapter. The owner or operator must maintain logs that show the precise TIS (hours) to determine the next due date. For engines with unknown TIS on the effective date, the AD requires inspections within 25 hours, which may force an immediate grounding if the aircraft is approaching its annual inspection.

Right to use later revisions. The AD requires compliance with MSB94-4G dated 31 October 2005 or later FAA-approved revisions. This means that if TCM issues an updated version of the service bulletin that is approved by the FAA, the operator may use that newer version instead of the 2005 version. However, the AD does not automatically approve later CASA revisions; it specifically references FAA-approved revisions. This could create a situation where a later revision is FAA-approved but not yet recognised by CASA. In practice, CASA tends to harmonise, but the AD text is explicit.

Right to use equivalent bearing. For the needle bearing replacement, the AD allows use of an equivalent approved bearing in place of the specific bushing P/N 654472. This provides some flexibility, but the equivalence must be approved, likely by CASA or the FAA following standard procedures.

Right to rely on earlier inspections. For engines that have already been inspected in accordance with the AD at any revision status, the first compliance interval starts from the next 100-hour TIS or annual inspection after the effective date. This means operators who were already compliant under Amendment 1 or 2 do not need to restart the clock from zero; they continue from where they are.

No right to defer due to parts shortages. The AD does not provide any extension or waiver for parts unavailability. If a required part is not available, the aircraft remains grounded until it is obtained. This is a significant commercial risk for operators of less common aircraft models.

The AD itself does not specify penalties. However, airworthiness directives issued under the Civil Aviation Act 1988 (Cth) and the Civil Aviation Safety Regulations 1998 (CASR) are legally enforceable. Non-compliance with an AD is a breach of the regulations and can attract both administrative and criminal penalties.

Under CASR 42.105 (as it stood in 2007), the operator of an aircraft must ensure that the aircraft is maintained in an airworthy condition and that all applicable ADs are complied with. Failure to do so is an offence. The maximum penalty for a contravention of a safety regulation can be significant, potentially up to hundreds of penalty units for an individual and more for a body corporate. A penalty unit in 2007 was $110; so 200 penalty units would be $22,000. However, for serious safety breaches, prosecution could lead to higher fines, and for individuals, imprisonment is theoretically possible under the Act for reckless endangerment, though rarely applied for AD non-compliance alone.

Additionally, CASA has the power to suspend or cancel an aircraft’s certificate of airworthiness or registration if it is not maintained in an airworthy condition. An aircraft that is not compliant with an AD is technically unairworthy. Flying such an aircraft is illegal and would expose the pilot and operator to enforcement action, as well as voiding insurance.

The AD provides its own immediate enforcement mechanism: the prohibition on special flight permits for rough-running engines. This means CASA cannot legally issue a permit to fly an aircraft that is rough-running, even for maintenance. If an operator attempted to fly without a permit, that would be an additional violation.

It is worth noting that the AD does not list any specific penalties for the maintenance organisation that performs incorrect inspections. However, a LAME who certifies an aircraft as compliant when it is not can face disciplinary action from CASA, including suspension or cancellation of their licence.

The enforcement reality is that CASA conducts audits and spot checks. For general aviation operators, AD compliance is often verified during regular maintenance inspections or when a certificate of airworthiness renewal is sought. For commercial operators, AD compliance is audited under their maintenance control manual and periodic surveillance.

There is no private right of action in the AD itself, but non-compliance could be used as evidence of negligence in civil litigation if an accident occurs. The background explicitly references a fatal accident report, so the stakes are high.

Ultimately, the economic cost of non-compliance includes not only potential fines but also the indirect costs of grounding, investigation, and reputational damage. For a small operator, a grounding due to non-compliance could be more expensive than the fine.

The AD explicitly references two external documents: TCM Mandatory Service Bulletin MSB94-4G (dated 31 October 2005 or later FAA-approved revisions) and FAA Airworthiness Directive 2007-05-15 Amendment 39-14976 dated 12 March 2007.

Relationship with the TCM Service Bulletin. The AD does not reproduce the inspection procedures; it incorporates them by reference. This means that the legal requirements of the AD are partially defined by the content of the service bulletin. If the bulletin changes (subject to FAA approval), the AD’s requirements may effectively change without a direct amendment to the AD text. However, the AD grants the right to use later FAA-approved revisions, so the operator must monitor both the TCM bulletin and FAA approval status.

Relationship with the FAA AD. The Australian AD states that it refers to the FAA AD. This suggests that the CASA AD is harmonised with the US directive, which is common for engines type-certificated in the US and used on Australian-registered aircraft. Operators should be aware that compliance with the Australian AD may not automatically satisfy all obligations under the FAA AD for aircraft operating in US airspace. Conversely, an aircraft that has complied with the FAA AD in the US might still need to ensure compliance with the Australian version for Australian registration.

Interaction with the Civil Aviation Safety Regulations. The AD is issued under the authority of the Civil Aviation Act and the associated regulations. It has legal force similar to a regulation. It would override any conflicting provisions in an aircraft’s maintenance manual or the manufacturer’s non-mandatory service information. However, the AD does not purport to amend the type certificate data sheet or the aircraft’s flight manual; it is an additional airworthiness limitation.

Interaction with other ADs. The AD does not cite any other ADs beyond the FAA reference. However, there may be other ADs applicable to the same airframe or engine (e.g., ADs for the propeller, airframe structure, or other engine components). Compliance with this AD does not relieve the owner from complying with all other applicable ADs. In particular, ADs that mandate overhaul intervals or life limits for related components (such as the crankshaft gear) might interact with the inspection cycles in this AD.

Interaction with normal maintenance schedules. The AD aligns its recurring inspections with the 100-hour or annual inspection intervals, whichever comes first. This reduces the incremental burden by dovetailing with existing maintenance events. However, the AD also imposes separate 400-hour cycles for the starter adapter, which may not coincide with other scheduled maintenance. Operators must carefully track the starter adapter TIS separately.

Interaction with flight operations. The AD’s prohibition on special flight permits for rough running engines is absolute. This overrides any other regulation that might allow a ferry permit for an otherwise unairworthy condition. Also, the AD does not provide any dispensation for test flights or positioning flights post-repair; the aircraft must be fully compliant before flight.

Interaction with insurance law. Non-compliance with an AD is likely to be a breach of policy conditions in aircraft hull and liability insurance. If an accident occurs and the AD was not complied with, the insurer may deny coverage. The AD’s reference to a fatal accident report underscores the severity.

The source document is Amendment 3 of AD/CON/84, and it provides limited details of the prior amendments.

Original AD/CON/84. The initial issuance date is not specified in the source, but the directive was first issued after the original series of service difficulty reports. The original AD would have mandated actions based on an earlier version of the TCM Service Bulletin (likely MSB94-4 or earlier revisions).

Amendment 1. Effective 2 November 2005. The source does not describe the content of this amendment. It is reasonable to infer that it updated the AD to reference a newer revision of the service bulletin or adjusted compliance times.

Amendment 2. Effective 22 December 2005. Again, no specific changes are noted in the source. The background states that Amendment 2 became effective on that date.

Amendment 3. Effective 10 May 2007. This is the current amendment. According to the background, the amendment makes reference to the latest revision of TCM service documents (MSB94-4G dated 31 October 2005) and the latest FAA AD 2007-05-15. The FAA AD itself is dated 12 March 2007, which suggests that the previous Australian amendment was referencing an older FAA AD. The FAA AD number is given as AD 2007-05-15 Amendment 39-14976.

The amendment history shows that the CASA AD has been updated at least three times in less than two years. This pattern suggests an evolving understanding of the failure mode and the appropriate corrective actions. It also imposes a compliance burden on operators who must check which amendment they are complying with, especially if they have already performed actions under an earlier amendment. Fortunately, the AD provides that engines inspected under any revision status continue the inspections from the next interval after the effective date of Amendment 3. That is, the prior work is not wasted; it counts.

There is no information in the source about any proposed or future amendments. The AD is still current as of 2007; for the purposes of this deep dive, we treat it as final. But in practice, operators should always check the CASA website for any further amendments or cancellations.

The amendment history is also relevant for understanding the progression of events. The original AD likely followed the earlier service difficulty reports; Amendment 1 and 2 were quick follow-ups; Amendment 3 incorporates the post-accident analysis. The fatal accident report mentioned in the background may have occurred after the earlier amendments were issued, prompting the latest revision.

The source document does not cite any litigation, nor does it refer to any court cases. This is typical for an airworthiness directive. ADs are technical regulatory instruments, not the subject of frequent litigation. However, there are several potential litigation contexts that are relevant to this AD.

Accident litigation. The background states that the AD results from six service difficulty reports and one fatal accident. In any civil litigation arising from that accident, the AD and its prior versions would be highly relevant as evidence of the known risk and the manufacturer’s and regulator’s response. If the accident aircraft was not in compliance with the AD at the time of the accident, that non-compliance could be a basis for a finding of negligence per se. Conversely, if the aircraft was compliant but the failure still occurred, product liability claims could be pursued against TCM.

Regulatory challenges. An owner or operator could theoretically challenge the validity of the AD on grounds such as procedural error or unreasonableness. However, under Australian administrative law, judicial review of CASA decisions is difficult. The test for a meritorious challenge would be very high, and there is no record of such a challenge to this particular AD in public databases. ADs are generally accepted as necessary safety measures.

Insurance litigation. If an accident occured and the aircraft was not compliant with the AD, an insurer might deny coverage. The insured could then sue the insurer for breach of contract, leading to litigation over whether the non-compliance was material and causal. Conversely, if the aircraft was compliant but the AD was later found to be inadequate, product liability claims against TCM or the engine rebuilder might arise.

Maintenance disputes. A licensed engineer who fails to perform the required inspections could be sued by the aircraft owner for breach of contract or negligence. The AD sets the standard of care; failure to comply with it would be prima facie negligence.

Administrative enforcement. CASA can issue infringement notices or initiate prosecution for non-compliance. An operator might challenge the penalty on grounds of factual error or lack of knowledge, but the AD is strict liability in nature. There is no reported case in the source.

In summary, while there is no known litigation history for AD/CON/84 Amdt 3 specifically, the AD is relevant in a variety of legal contexts. The absence of cited cases does not mean no cases exist; it means the source does not mention them. For the purposes of this deep dive, we must not invent any. The risk of litigation for non-compliance is real but not quantified.

Several traps and nuance points in this AD can easily trip up even experienced operators.

Rough running means immediate grounding with no ferry permit. The AD is absolute: special flight permits are prohibited for rough-running engines. Many operators assume they can get a one-time ferry permit to fly to a repair base. They cannot. The aircraft must be repaired on site before any further flight. This can be a major logistical and cost issue if the rough running occurs far from a maintenance facility that can handle a GTSIO-520 engine.

Kit installation does not end the recurring inspections. Many owners will assume that once they install the starter adapter service kit (EQ6642 or EQ6642R), the problem is solved and the recurring 100-hour inspections for rough running and Part 2/3 can stop. But the AD explicitly states that installing the kit is not terminating action for the inspections. This means you might be doing an engine tear-down or partial inspection at every 100 hours forever, unless a future AD says otherwise.

Plus or minus 10 hours is a tolerance, not a grace period. The AD allows recurring inspections to be performed at 100 hours “plus or minus 10 hours”. That means you can do the inspection at 90 hours or 110 hours. But if you go to 111 hours, you are out of compliance. The tolerance does not apply to the initial 25-hour deadline for engines not previously inspected; that is a flat “within 25 hours TIS” with no tolerance. Also, the 400-hour deadline for the starter adapter has a tolerance of plus or minus 10 hours, but only for the recurring interval; the initial 25-hour deadline for high-time adapters is strict.

Needle bearing replacement is conditional on finding it. The AD says “if … you find needle bearing P/N 537721, installed in the crankcase, replace it.” That sounds straightforward, but it creates a potential trap. If during an inspection you do not find that specific bearing (perhaps because the crankcase already has a bushing or a different bearing), you may still need to perform the other inspections. The AD does not require a search for the bearing; it only triggers a replacement if it is encountered during the required inspections. However, a cautious engineer might argue that you cannot confirm the absence unless you specifically look. The AD’s language does not mandate that you dig deeper; it only imposes the replacement duty when the bearing is found.

The compliance deadlines for the starter adapter are tied to its own TIS, not the engine’s TIS. This is a trap. The starter adapter may have a different time-since-overhaul record than the engine. If the adapter was replaced earlier, its TIS might be lower than the engine’s. Operators must track both separately. If they only track engine TIS, they might miss the 400-hour adapter inspection.

Multiple aircraft models, but not all listed. The AD says engines are installed on, but not limited to, the listed aircraft. That means if you have a homebuilt or an experimental aircraft with a GTSIO-520 engine, you are still caught. There is no exemption for non-type-certificated aircraft unless the AD specifically says so (it does not).

The term “equivalent approved bearing” is undefined. For the bushing replacement requirement, the AD allows use of an “equivalent approved bearing” instead of P/N 654472. But what constitutes “equivalent” and who approves it? The AD does not say. Likely it means an FAA or CASA approved alternative part. But a mechanic might think a simple oilite bushing of the same dimensions suffices, which could lead to non-compliance.

No relief for parts shortages. The AD does not mention any provision for extending compliance if the service kit or bushing is not available. If the parts are on backorder, the aircraft remains grounded until they arrive. This can be a significant risk for less popular models.

Later FAA revisions must be approved. The AD allows use of later FAA-approved revisions of MSB94-4. But if TCM issues a revision that is not yet FAA-approved, or if FAA approval is withdrawn, the operator cannot use it. They must stick with the 2005 revision or a later one with documented FAA approval.

Compliance with this AD requires a systematic approach combining technical maintenance actions and record keeping. Below is a step-by-step guide grounded in the AD’s text.

Step 1: Obtain current documents. Obtain the latest version of TCM Mandatory Service Bulletin MSB94-4G (dated 31 October 2005) or any later FAA-approved revision. Also obtain the corresponding FAA AD 2007-05-15 for reference. Do not rely on older revisions of the bulletin; the AD specifically requires the G revision or later.

Step 2: Determine TIS for the engine and starter adapter. Review the engine and aircraft logbooks to find the time-in-service on the effective date of 10 May 2007. Record both the engine total TIS and the starter adapter’s TIS separately. If the starter adapter’s hours are unknown, treat it as 400 or more hours.

Step 3: Assess current compliance status. Determine whether the engine has been inspected in accordance with this AD at any revision status. If yes, then the next recurring inspection is due at the next 100-hour TIS or annual inspection after the effective date. If no, the first inspection must be completed within 25 hours TIS or the next annual, whichever comes first. The recurring interval then becomes every 100 hours TIS plus or minus 10 hours or annual, whichever is first.

Step 4: Schedule the initial inspection. If the engine has not been inspected, schedule the inspection as soon as possible, but not later than 25 hours TIS or the next annual. This is a mandatory deadline with no tolerance. For starter adapters with 400+ hours or unknown TIS, comply within 25 hours TIS. For less than 400 hours, schedule for the point when the adapter reaches 400 hours (or at the first inspection, note it).

Step 5: Perform inspection per Parts 1, 2 and 3. Follow the procedures in the TCM bulletin for Parts 1, 2 and 3. These likely involve disassembly and inspection of the starter adapter drive and crankshaft gear area. Document the findings. If rough running is present, the inspection must be done before further flight and will probably require Part 1 and 3 only at that time, but Part 2 also must be done at some point (see requirement 2). However, the safest approach is to do all three parts together.

Step 6: Replace needle bearing if found. During those inspections, if you encounter needle bearing P/N 537721 in the crankcase, replace it with bushing P/N 654472 or an equivalent approved bearing using Part 4 of the bulletin.

Step 7: Install service kit at next overhaul or adapter replacement. If the engine is due for overhaul or the starter adapter is being replaced, install service kit P/N EQ6642 or EQ6642R using Part 5 of the bulletin. This is not required immediately unless those events occur after the effective date. Record the installation, but keep in mind the recurring inspections continue.

Step 8: Repeat inspections at intervals. For engines: perform the full inspection sequence (Parts 1, 2 and 3) at each 100-hour TIS (plus or minus 10 hours) or annual, whichever comes first. For starter adapters: inspect the adapter every 400 hours TIS (plus or minus 10 hours). Even if the kit is installed, these cycles continue.

Step 9: Maintain accurate records. Log each inspection date, TIS at inspection, findings, parts replaced, and the technician’s signature. This is critical for proving compliance to CASA or insurance auditors. The use of the tolerance band (e.g., 90-110 hours) must be recorded to show compliance.

Step 10: Monitor for changes. Check periodically for new revisions of the TCM bulletin or new FAA ADs. If a later FAA-approved revision is issued, you may switch to it, but you must ensure the procedures are compatible with the AD’s requirements. Also watch for any updates to the Australian AD itself.

Step 11: No flight if rough running develops. If the engine exhibits a sudden increase in vibration that cannot be cleared by adjusting mixture control, do not attempt to fly. The aircraft is grounded immediately. Do not apply for a special flight permit; it will be refused. Arrange for mobile maintenance or a tow to a hangar. After the rough-running event, perform the Part 1 and 3 inspections before any further flight.

By following these steps, operators can meet the obligations of AD/CON/84 Amdt 3 while minimising disruption. The key is to treat the AD as a continuing obligation, not a one-time fix.