AD/CASA/26 Amdt 2 - Steering System Hydraulic Installation

The core concept is the “airworthiness directive” itself, a form of delegated legislation that mandates corrective action on aircraft type designs when an unsafe condition is identified. The directive references several technical documents that become legally binding. “Nose landing gear” or NLG refers to the forward landing gear assembly specific to the C-212 series. The directive requires “rework” of the NLG, meaning a set of detailed modifications described in CASA Service Bulletin 212-32-21 Revision 2. “Modification of the hydraulic steering system” refers to changes to the hydraulic components that control steering of the nosewheel, as defined in CASA Service Bulletin SB-212-32-22 Revision 2.

“Cable tension” is a measurement parameter for the steel cables that transmit pilot steering inputs to the nosewheel. The directive requires testing this tension and adjusting it if out of specification. The test must be performed in accordance with one of two specific CASA COM documents, each with a stated revision level. The choice between COM 212-172 and COM 212-173 depends on applicability, likely based on aircraft variant or modification status.

The “Aeroplane Flight Manual” or AFM is the approved document containing limitations, procedures and performance data for a given aircraft. The directive compels revision of the Limitations Section to include a specific procedural statement regarding rejected take-off (RTO) procedures in the event of nosewheel malfunction during the take-off run. This changes the operational envelope and crew procedures.

“Compliance” is expressed through both fixed calendar deadlines and recurring intervals. The original directive effective 17 March 2005 had deadlines: for Requirement 1, 30 May 2006; for Requirement 3, 17 September 2005 (six months after effective date). Requirement 2 is a continuing airworthiness requirement with an interval of 600 flight hours and an event-driven trigger when abnormal vibration occurs. Requirement 4 is an immediate prohibition from the effective date.

The directive distinguishes between the “original issue” and two amendments. Amendment 1 became effective 10 September 2005 and extended the compliance period for replacement of certain parts due to manufacturer supply constraints. This indicates that the original compliance timeline was not commercially feasible regarding parts availability. Amendment 2, effective 20 November 2008, corrected an error in the compliance section regarding the inspection interval following abnormal vibration. The exact error is not described, but the correction ensures that the vibration trigger is clearly part of the inspection requirement, not just the 600-hour interval.

“Service bulletins” and “COM documents” are manufacturer or CASA-issued instructions that are not normally legislative but become compulsory through the directive. The directive specifies precise revision levels and dates. Using an earlier or later revision is non-compliance unless explicitly allowed.

The directive also references Spanish AD 01/02. This indicates international harmonisation: the Spanish airworthiness authority issued an AD for the same design. The Australian directive may mirror or adopt the Spanish requirements, but the Australian AD stands as the independent legal requirement for Australian-registered aircraft.

“Abnormal vibration” is a trigger concept. The directive does not define objective criteria. It relies on pilot or maintainer judgment to identify vibration that is outside normal operating parameters. This creates potential subjectivity and compliance risk.

This directive directly impacts all owners and operators of Model C-212 series aeroplanes registered in Australia or operated under Australian regulatory authority. The C-212 is a light twin-turboprop transport aircraft manufactured by CASA (Construcciones Aeronáuticas SA) in Spain, first produced in the 1970s. The Australian fleet is small, likely comprising freight operators, parachute jump operators, regional passenger carriers, and possibly government agencies such as defence or border patrol. Each operator faces direct compliance costs: parts procurement, labour for modifications and inspections, aircraft downtime, and administrative burdens for updating the AFM and maintenance records.

Maintenance organisations that hold approvals under Part 145 of the Civil Aviation Safety Regulations (CASR) must have the capability and authorisation to perform the rework, modification, and cable tension tests. They must obtain the correct revision of each service bulletin and COM document. Their staff must be trained on the specific procedures. The directive imposes no obligations on the manufacturer directly, but the supply chain is affected: part suppliers and the manufacturer must produce the required modification kits and replacement parts. Amendment 1 was necessitated by the manufacturer’s inability to supply parts within the original compliance timeline, indicating that supply constraints can delay regulatory compliance and force extensions.

CASA is the regulator responsible for issuing, amending and enforcing the directive. Its inspectors verify compliance during audits and ramp checks. Aircraft that do not comply may be grounded, and enforcement action may follow. The Spanish aviation authority is indirectly affected because the directive references Spanish AD 01/02, suggesting coordination but also potential inconsistency if the two directives diverge.

Insurers and financiers are affected indirectly. Non-compliance with an airworthiness directive typically voids insurance coverage and may trigger loan defaults or reduce aircraft residual value. Lessors will require evidence of compliance before leasing or purchasing aircraft. Potential buyers must verify that all three requirements (including ongoing Requirement 2) have been satisfied with the correct document revisions.

The applicability clause is broad: “All Model C-212 series aeroplanes.” There are no exemptions for specific registrations, configurations, or operational categories. This includes aircraft used for private operations, commercial air transport, aerial work, or training. The directive applies regardless of whether the aircraft is currently flying or in storage: a stored aircraft must comply before returning to service.

The economic impact is concentrated on a small number of operators. For a fleet of one to five aircraft, the per-aircraft cost of the rework, modification, and cable tension test equipment can be significant relative to the aircraft’s value. The directive does not provide for cost recovery, subsidies, or alternative compliance options. Operators must bear the cost entirely. For some smaller operators, the directive may accelerate retirement decisions, affecting the supply of ageing aircraft in the Australian market.

The directive imposes four primary duties. First, the operator must ensure the NLG rework and hydraulic steering modification are accomplished in accordance with the specified service bulletins. This is a one-time action unless not previously performed. The phrase “unless previously accomplished” provides a right to rely on prior work, but the operator bears the burden of proof. They must have maintenance records demonstrating that the work was done using the correct bulletin revisions.

Second, the operator must perform the cable tension test at intervals not exceeding 600 flight hours, and whenever abnormal vibration of the nosewheel steering system occurs. This is a continuing duty that extends for the life of the aircraft. The operator must establish procedures to track flight hours and to detect and report abnormal vibration. The duty is triggered by vibration events, which rely on pilot or maintainer judgment. Failure to recognise abnormal vibration and initiate a test is a breach of the directive.

Third, the operator must revise the Limitations Section of the AFM to include the specified RTO procedure statement. This can be done by inserting a copy of the directive. The operator has the right to remove the copy later if a general AFM revision includes an identical statement. The duty is to ensure the limitation remains in the AFM at all times. If the AFM is later revised without that statement, the operator must reinsert the directive copy or otherwise include the limitation.

Fourth, the operator must not install any NLG that has not been reworked in accordance with paragraph (1)(a). This duty applies to any person installing an NLG on a C-212, including maintenance organisations. The duty is not limited to operators but extends to those performing installation. It effectively banns unmodified NLG from the fleet.

Operators have the right to choose which COM document to use for the cable tension test, but must select the applicable one based on the aircraft configuration. They do not have the right to deviate from the prescribed service bulletins or COM documents without obtaining an alternative means of compliance from CASA. The directive does not grant any general exemption power.

There is no right to an extension or waiver. The compliance deadlines are mandatory. If parts are unavailable, the operator cannot fly non-compliant; they must ground the aircraft or apply for a specific extension through CASA’s discretionary powers outside the directive.

The operator also has a duty to keep records of compliance. These records should demonstrate the date of accomplishment, the personnel or organisation involved, the part numbers and serial numbers of modified components, and the results of cable tension tests. The records must be available for inspection by CASA.

The directive does not specify penalty provisions itself, but it is issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998. Non-compliance with an airworthiness directive is an offence under CASR Regulation 42.030 (as in force at the time). Penalties include fines, imprisonment for individuals, and corporate fines. Additionally, CASA may suspend or cancel the aircraft’s certificate of airworthiness. That effectively grounds the aircraft. CASA can also issue a direction prohibiting operation until compliance is achieved.

Enforcement is carried out by CASA inspectors through audits, ramp checks, and investigation. They will review maintenance records and inspect the aircraft. If non-compliance is discovered, the inspector can issue a report leading to enforcement action. The directive does not provide for infringement notices (on-the-spot fines) but such mechanisms exist under the Act for minor breaches. However, non-compliance with a safety-critical AD is unlikely to be treated as minor.

The directive also creates a prohibition on installing unmodified NLG. A maintenance organisation that installs an NLG that has not been reworked may face enforcement action, including possible suspension of its maintenance approval. The operator who accepts the aircraft also bears responsibility.

Continuing non-compliance after a compliance deadline is a continuing offence. Each day of operation may constitute a separate breach. The directive does not offer a grace period.

The background notes that Amendment 1 extended the compliance period for certain parts because of manufacturer supply delays. This suggests that inability to obtain parts was considered a factor, but only at the regulatory level: individual operators cannot claim impossibility as a defence unless CASA has granted a specific extension. The directive does not contain a “force majeure” or impossibility defence.

In practice, the most likely consequence of non-compliance is grounding of the aircraft. CASA may issue a ground direction under Section 20BB of the Civil Aviation Act. The aircraft cannot fly until the directive is complied with. This imposes immediate economic loss.

Insurance consequences are severe. Most aviation insurance policies require compliance with all applicable ADs as a condition of coverage. If an accident occurs involving a non-compliant system, the insurer may deny coverage entirely, leaving the operator liable for hull loss, third-party damage, and personal injury claims. Criminal prosecution could also follow if the non-compliance contributed to an accident.

There is no reference to any defence of due diligence or reasonable mistake in the directive. Strict liability likely applies: if the required action was not performed by the deadline, the operator is in breach regardless of the reasons, subject to general criminal law defences such as honest and reasonable mistake of fact, but that would be difficult to establish given the clear wording.

This directive is a legislative instrument made under the Civil Aviation Act 1988. It sits within the hierarchy of aviation safety regulation. The general law requires that all aircraft hold a valid certificate of airworthiness and be maintained in an airworthy condition. Compliance with applicable ADs is a condition of airworthiness. This directive overrides any conflicting provisions in manufacturer maintenance manuals, operator manuals, or other guidance unless those provisions are more restrictive. If a later regulation or AD conflicts, the later instrument may supersede, but this directive remains in force until explicitly withdrawn or amended.

It interacts with CASR Part 42 (Continuing Airworthiness) and Part 145 (Approved Maintenance Organisations). Part 42 requires that operators have a system to track and comply with ADs. The directive specifies that the cable tension test may be performed using either COM 212-172 or COM 212-173; the operator must ensure that the chosen method is within the scope of their maintenance organisation’s approval. The directive also creates a requirement to revise the AFM, which is an approved document. Normally, changes to the AFM require CASA approval, but the directive itself provides the authority for that change. The operator must follow the procedure in the directive to incorporate the limitation.

The directive references Spanish AD 01/02. While the Spanish AD is not directly enforceable in Australia, it may be used by CASA as evidence of the unsafe condition or as a basis for the required actions. If the Spanish AD is later revised, that revision does not automatically affect the Australian directive; only an amendment to the Australian AD will change obligations. However, operators who also operate in Spain or under Spanish design authority may need to comply with both.

The directive does not explicitly displace any state or territory workplace health and safety laws, but those laws may impose additional obligations on persons performing the rework and modification, such as safe handling of hydraulic systems, pressure testing, and use of lifting equipment. The directive is silent on those matters.

There is no interaction with trade practices or competition law. However, the compliance cost may affect the value of C-212 aircraft and the market for their operation. The directive may lead to early retirement of aircraft if the cost of compliance is disproportionate to their remaining economic life. This could reduce competition in niche markets served by C-212s.

The directive also interacts with the aircraft’s type certificate. The modifications required by the service bulletins are likely already approved under the type certificate. The AD makes them mandatory. If the modifications have not been incorporated into the type design, the AD may require a supplemental type certificate or other approval, but the directive does not specify this.

Records of compliance must be made and retained in accordance with CASR Part 42. The directive does not alter those record-keeping obligations but adds specific items to be recorded, such as the revision of the service bulletin used and the date of accomplishment.

The source provides a clear amendment history. The original issue of AD/CASA/26 became effective on 17 March 2005. It contained the initial requirements to rework the NLG, modify the hydraulic steering system, test cable tension, revise the AFM, and prohibit installation of unmodified NLG. Compliance deadlines were set: Requirement 1 by 30 May 2006, Requirement 3 within six months of the effective date, and Requirement 2 ongoing at 600-hour intervals and after abnormal vibration.

Amendment 1 became effective on 10 September 2005, only about six months after the original. It extended the compliance period for replacement of certain parts. The background explains that this extension was due to the manufacturer being able to supply those parts in the required time frame. The implication is that the original compliance period was not feasible because the manufacturer could not deliver parts quickly enough. Amendment 1 did not change the substantive actions, only the deadline for part replacement. The other requirements remained in force unchanged.

Amendment 2 is the version provided and became effective on 20 November 2008, over three years after Amendment 1. Amendment 2 corrects an error in the compliance section. The error concerned the inspection interval following any abnormal vibration within the nosewheel steering system. The amendment clarifies that the inspection is required both at the 600-hour interval and whenever abnormal vibration occurs. This is not a substantive change to the requirement but a correction of ambiguous drafting. Operators who may have interpreted the original wording as requiring the inspection only at the 600-hour interval (and not after vibration events) would have been non-compliant if vibration occurred and no inspection was performed. Amendment 2 removes that ambiguity.

The source also shows that the directive references Spanish AD 01/02 dated 17 April 2002. That Spanish AD predates the Australian original by three years. It is likely that the Australian directive was modelled on the Spanish one, but with adjustments for Australian conditions, as reflected in the amendments.

The amendment history reveals that airworthiness directives are not static. They can be adjusted to address practical supply constraints and drafting errors. Operators must track amendments carefully. Relying on an outdated version could lead to non-compliance. For this directive, any operator who only held the original issue would be unaware of the part replacement extension from Amendment 1 and might have grounded the aircraft unnecessarily if they could not obtain parts in time, or worse, they might have missed the corrected wording from Amendment 2 and misinterpreted the vibration inspection trigger.

The effective date of Amendment 2, 20 November 2008, marks the date from which the corrected wording applies. Operators who achieved compliance before that date using the original wording would still be compliant if they properly interpreted the original, but to be safe, they should ensure their records reflect the amendment.

The source does not mention any litigation history. There is no reference to court cases, tribunal decisions, or legal challenges to the directive or its amendments. This is consistent with the nature of airworthiness directives: they are technical instruments typically enforced administratively rather than litigated. It does not mean that no legal action ever occurred, but the directive itself does not record any.

It is possible that an operator challenged the directive or its amendments in the Administrative Appeals Tribunal (AAT) or the Federal Court, but that would not be noted in the AD text. Such challenges are rare because ADs are usually issued after technical investigation and are difficult to contest on merits. An operator could argue that the directive is unreasonable or procedurally flawed, but the standard of review gives significant deference to CASA’s safety judgment.

The Spanish AD 01/02 may have been litigated in Spain or Europe, but that is outside the scope of this source.

The absence of litigation history can be interpreted as the directive being accepted by the industry without legal contest. That could indicate that the affected industry, being small, chose to comply rather than fight. Alternatively, it may be that any disputes were resolved informally with CASA, such as through extensions or alternative means of compliance requests. Amendment 1, which extended the compliance period for parts, may have been a response to pressure from operators rather than a court order.

In practice, operators facing compliance difficulties are more likely to apply for an alternative means of compliance or a time extension than to litigate. CASA has discretion to grant such relief. The directive itself does not mention an AMOC process, but it exists under the CASR.

The correction in Amendment 2 for an error in the compliance section could have been the result of an internal audit or operator feedback, not a court decision.

Therefore, we can state that no litigation is recorded in the source. This is a neutral fact but also a useful risk indicator: the directive has not been judicially tested, so its interpretation remains subject to CASA’s administrative interpretation. If disputes arise, there is no binding precedent to guide interpretation.

Several traps await operators and maintainers of C-212 aeroplanes under this directive. The most significant is the precise document revision requirement. The rework must use CASA Service Bulletin 212-32-21 Revision 2 dated 10 November 1987. The hydraulic modification must use SB-212-32-22 Revision 2 dated 28 July 1997. Using an earlier or later revision is non-compliance. Operators who perform the work “in accordance with” a later revision that includes additional changes may be in breach if the later revision is not explicitly allowed. The directive does not adopt revisions by reference to the latest revision; it fixes specific revisions.

The cable tension test can use either COM 212-172 Revision 4 or COM 212-173 Revision 3, but only those specific revisions. The operator must determine which applies. If the wrong document or wrong revision is used, the test is not compliant. The directive does not provide guidance on which COM document applies to which aircraft configuration. The operator must rely on the aircraft’s maintenance history or consult the manufacturer.

The phrase “unless previously accomplished” can lead to a false sense of compliance. Operators may assume that earlier NLG work satisfies the requirement, but that work must match exactly the specified bulletin revision. If the NLG was reworked using an earlier revision of the service bulletin, or using a non-CASA bulletin, the requirement is not met. The operator must trace records back to the specific bulletin.

The event trigger under Requirement 2 is “abnormal vibration of the nosewheel steering system”. The directive does not define “abnormal”. It relies on subjective assessment by the pilot or maintainer. There is no threshold, no vibration measurement standard. This creates uncertainty: a cautious operator may do a test after every slight vibration, increasing maintenance burden and downtime; a less cautious operator may dismiss vibrations as normal and miss a mandatory trigger. If an incident occurs, CASA may judge that a reasonable person would have considered the vibration abnormal, making the operator non-compliant retroactively.

The AFM revision requirement must include the exact statement as written. The directive allows inserting a copy of the AD. But the note says that if general revisions of the AFM include the same statement, the copy may be removed. The trap is that the general revision must include an “identical” statement. If the general revision uses slightly different wording (e.g., “perform” without quotes, or “initiate” instead of “initiate or 'perform'”), the limitation is not identical, and removing the AD copy would be non-compliant. Operators must compare the wording precisely.

Requirement 4 prohibits installation of an unmodified NLG from the effective date. This applies not only to new installations but also to re-installation of an existing NLG after removal. If an operator removes the NLG for other maintenance, they must ensure it is reworked before reinstallation, even if it was previously compliant. However, if the NLG was already reworked per (1)(a), it is fine. The trap is that an NLG that was never reworked cannot be installed even temporarily.

The compliance deadlines in the directive are not fully restated in the amendment. Amendment 2 changes the effective date and corrects wording but states that Requirement 1 remains “Before 30 May 2006” and Requirement 3 remains “Within 6 months after the effective date of the original issue”. For aircraft that entered the fleet after those dates, the deadlines have passed, meaning they must have been compliant at the time of entry, or now be non-compliant. New operators acquiring a C-212 must verify that Requirement 1 and 3 were accomplished before they took ownership. They cannot simply comply now because the deadlines are historical. The directive does not create a new deadline for new owners; it simply requires that the actions were previously accomplished. If not, the aircraft is grounded until the work is done, but the deadline in the directive is no longer enforceable as a future date; rather, non-compliance is a current condition.

Amendment 1 extended the compliance period for replacement of certain parts. But the extension was for “replacement of certain parts” not for the rework or modification. Operators may mistakenly think the entire compliance period was extended. They must read the background carefully to understand which parts were affected.

The directive references Spanish AD 01/02. That AD may have different compliance dates or additional requirements. Operators who rely solely on the Australian AD may miss a requirement that is incorporated by reference or considered part of the design standard. CASA could take the view that the Spanish AD is the underlying source, and any deviation from it is non-compliance. The interaction is unclear.

Finally, the directive does not provide an alternative means of compliance (AMOC) within its text. Operators who develop an equivalent solution must apply to CASA for an AMOC separately. This adds time and administrative burden.

Compliance with AD/CASA/26 Amdt 2 requires a systematic and documented approach. The operator must first obtain the full text of the directive and all referenced documents: CASA Service Bulletin 212-32-21 Revision 2, CASA Service Bulletin SB-212-32-22 Revision 2, and either CASA COM 212-172 Revision 4 or CASA COM 212-173 Revision 3. These documents are available from CASA or the aircraft manufacturer. The operator should verify the revision dates and ensure they hold the exact revision specified. Hold all documents in the aircraft technical records system.

For Requirement 1, the operator must determine whether the NLG rework and hydraulic steering modification were previously accomplished. Review maintenance records and logbook entries. Look for references to the specific service bulletin numbers and revision levels. If the work was done but with an earlier revision, it is not compliant. If compliant, record the evidence and place a notation in the compliance tracking system. If not compliant, arrange to perform the work. The work must be carried out by a Part 145 approved maintenance organisation with appropriate C-212 capabilities. The aircraft will need to be grounded for the duration. Parts may need to be ordered from the manufacturer. Note that Req 4 prohibits installation of unmodified NLG, so spare units must also be reworked before installation.

For Requirement 2, after initial compliance (which may be part of the same work package), establish a recurring inspection schedule. The 600-flight-hour interval should be tracked in the aircraft’s maintenance programme. Also establish a procedure for pilots and maintenance personnel to identify and report abnormal vibration of the nosewheel steering system. This could be a checklist item or a logbook annotation. Each test must be performed using the applicable COM document. The chosen COM document should be specified in the maintenance schedule. All test results and adjustments must be recorded.

For Requirement 3, insert a copy of AD/CASA/26 Amdt 2 into the Limitations Section of the AFM. Ensure the copy includes the statement from paragraph 3. If previous compliance was achieved by inserting the original AD or Amendment 1, verify that the statement in the AFM matches the current amendment. If the AFM already has a general revision that includes the identical statement, the copy may be removed, but retain evidence of compliance with the original requirement. The AFM revision must be recorded in the aircraft logbook and the AFM itself.

For Requirement 4, before installing any NLG, verify that it has been reworked in accordance with paragraph (1)(a). This applies to new, used, or overhauled units. Obtain a statement from the parts supplier or maintenance organisation that confirms the rework was done per the specified bulletin. Keep that documentation.

Maintain a compliance log that lists each requirement, its compliance status, the date of accomplishment, the document revision used, and the signature of the certifying person. Use a system to track the 600-flight-hour interval and the vibration trigger. Consider using a computerised maintenance management system.

Audit the work periodically. When CASA conducts an audit, have all records ready for review. Also, stay informed of any further amendments to this directive. Subscribe to CASA’s airworthiness directive notification service.

If there is any doubt about the applicability of a COM document or the meaning of “abnormal vibration”, seek clarification from CASA in writing. If parts are unavailable, apply for an alternative means of compliance or an extension before the deadline expires. Do not assume that impossibility of obtaining parts is a defence.

Finally, consider the economic impact. The cost of parts, labour, and downtime may be significant. Plan the work during a scheduled maintenance downtime to minimise additional lost revenue. For aircraft nearing end of life, evaluate whether compliance is economically justified or whether retirement is preferable. Weigh the cost against the safety benefit stated in the background: preventing failure of the auxiliary landing gear direction system and consequent reduced controllability. In any event, compliance is mandatory. The directive does not provide for exemptions based on economic hardship.