AD/INST/42 - KSA 470 Autopilot Servo Actuator

Applicability: The directive applies narrowly to Allied Signal Bendix/King Model KSA-470 autopilot servo actuators, specifically part numbers 065-0076-10 through 065-0076-15, serial numbers 0001-3081 inclusive. The AD lists a sample set of aircraft types and the corresponding part numbers and axis locations where these actuators are “known to be fitted” (for example, Raytheon (Beech) 400 Series KFC 400 with part 065-0076-11 on the yaw axis, Dassault Falcon 20 with part 065-0076-15 on the pitch axis, Learjet 31A KFC 3100 parts 065-0076-12/14/15 depending on axis, and so on). The list is presented as non-exhaustive: “The actuators are known to be fitted to, but not limited to the aircraft listed below.” That expands the practical scope beyond the enumerated aircraft to any installation matching the part and serial number criteria.

Mod 3: The operative technical remedy is the incorporation of “Mod 3.” The directive does not reproduce the Mod 3 technical steps; instead it requires that replacement be “with an actuator that incorporates Mod 3, in accordance with procedures in the applicable maintenance manual.” That links authorised compliance to the maintenance manual’s instructions rather than to instructions reproduced in the AD itself.

Two-fold mandatory effect: (1) retrofit/replacement of installed actuators to Mod 3 within a defined flight-time window; and (2) prohibiting installation of unmodified actuators after the effective date. The first is a corrective compliance requirement with a quantified metric (100 hours time in service), the second is a preventive control on parts circulation and future maintenance actions.

Safety mechanism: The background identifies the failure mode as loose roll pins inside the servo housing which can “fall out and become lodged in the output shaft, preventing this mechanism from disengaging.” The AD’s safety logic is: preventing loose pins (through Mod 3) removes the mechanical pathway that could cause the servo to jam, thereby reducing pilot workload and the risk of loss of control of the affected flight control axis.

Temporal and regulatory anchoring: The directive becomes effective on 18 June 1998 and expressly refers to FAA AD 98-08-20. The compliance timing and the prohibition on installation create immediate operational constraints from the effective date (installation ban) and a short-term compliance window (100 hours TIS) for fitted units.

Documentary dependency: The AD delegates detailed technical steps to the “applicable maintenance manual.” That creates a dependency on whatever the manufacturer’s or approved maintenance organisation’s manual prescribes for Mod 3 incorporation and for certification of the work.

Aircraft operators: Operators of any aircraft fitted with a KSA-470 actuator within the listed part-number/serial-number range must act. The AD lists specific aircraft manufacturers and models where these actuators are known to be fitted (Raytheon (Beech) 200/300/400 series with KFC 400, Dassault Falcon 20, Fairchild types, Learjet 31A with KFC 3100, Lockheed S-2 Tracker with KFC 325, Piper 400LS/PA-42-1000 and others). The AD qualifies that the list is not exhaustive, so any operator with the affected part/serial number combination is captured even if their aircraft is not on the printed list.

Maintenance organisations and approved engineers: The directive requires the replacement “in accordance with procedures in the applicable maintenance manual.” That makes maintenance providers the agents of compliance. Approved maintenance organisations, licensed engineers, and certifying staff carry responsibility for correct incorporation of Mod 3 and for logbook entries or other regulatory paperwork showing compliance.

Owners of spare parts and supply-chain actors: The AD forbids installing any actuator listed in the applicability statement that “has not had Mod 3 incorporated” on any aeroplane as of the effective date. This affects inventories held by spare-parts suppliers, overhaul shops, brokers and lessors. Stock that is not Mod 3-compliant becomes unusable for installation on aircraft covered by the AD. Supply-chain actors must either obtain Mod 3-compliant stock, perform Mod 3 on existing items per maintenance manual, or segregate and label non-complying stock to prevent inadvertent installation.

Regulators: CASA is the issuing authority and is the decision-maker for enforcement and interpretation. The AD references FAA action, so national regulators, continuing airworthiness authorities, or operators with cross-border operations must align with both CASA’s directive and the FAA’s referenced AD where applicable.

Pilots and flight operations: Pilots are indirectly affected because a failure mode the AD addresses , a servo actuator failing to disengage due to a lodged roll pin , can “result in an increased effort by the pilot to control the aircraft and possible loss of control of the affected flight control axis.” The AD reduces that mechanical risk, albeit by imposing maintenance and operational constraints.

Lessors and lessees: Leasing contracts may be affected because the AD imposes maintenance obligations within a short service-time window. The lessee or owner who is contractually responsible for continuing airworthiness will bear replacement cost and scheduling consequences unless contractually transferred.

Insurance underwriters and risk assessors: While not named, insurers assess exposure to regulatory non-compliance and elevated mechanical risk. The AD changes the risk calculus for aircraft with affected actuators until Mod 3 is incorporated.

Duties , what the AD requires

• Replace affected actuators: Requirement 1 states: “Replace the autopilot servo actuator with an actuator that incorporates Mod 3, in accordance with procedures in the applicable maintenance manual.” This is an affirmative replacement duty for any actuator within the Applicability list and serial numbers.

• Prohibition on installation of unmodified actuators: Requirement 2 is categorical: “An actuator, listed in the Applicability Statement, that has not had Mod 3 incorporated may not be installed on any aeroplane.” That prohibition takes effect “as of the effective date of this directive.”

• Compliance timing: The AD sets explicit compliance timelines. Compliance item 1 requires operators to complete replacement “within the next 100 hours time in service after the effective date of this directive.” Compliance item 2 sets the installation ban as effective immediately on the directive’s effective date.

• Follow maintenance manual procedures: The directive conditions work on the “applicable maintenance manual.” That places a duty on the maintenance agent to perform Mod 3 strictly in accordance with the manual’s procedures; the AD does not prescribe alternative procedures.

Rights and discretionary elements

• Right to perform Mod 3 in situ or install a Mod 3-compliant actuator: The AD requires replacement with an actuator that “incorporates Mod 3.” That permits two compliance pathways in principle: (a) modify the existing actuator to incorporate Mod 3 if allowed/possible per the maintenance manual, or (b) install a replacement actuator that already incorporates Mod 3. The AD does not force a new-purchase pathway exclusively.

• Right to rely on the maintenance manual: The AD explicitly anchors the technical method to the “applicable maintenance manual.” That limits arbitrary alternative procedures and gives the maintenance organisation the right to follow approved manufacturer/maintenance-approved methods.

• Procedural right to documentation: Implicit in aviation maintenance regulation (and consistent with the AD’s instruction to follow the maintenance manual) is that the work must be documented per regulatory maintenance record requirements. The AD itself, however, does not reproduce those logbook or release-to-service obligations; they remain those prescribed by the Civil Aviation Regulations and accepted maintenance practice.

Who decides and who certifies

• CASA issues the directive and establishes the effective date (18 June 1998). The maintenance organisation and certifying engineer decide the method within the maintenance manual’s instructions and certify the work as complete and airworthy.

Consequences of non-compliance

• The AD does not itself list civil penalties or criminal sanctions for non-compliance in the text provided. It is issued under CAR Part 39-107, so enforcement is within the regulatory framework, and non-compliance would expose operators to regulatory enforcement action under the CARs. The AD, however, specifies mandatory corrective action and timing that leave operators with no discretionary grace beyond the stated 100 hours TIS window.

Directive status and scope of enforcement

• The instrument is an airworthiness directive issued under the Civil Aviation Regulations 1998, Part 39-107. The directive is prescriptive: it requires specific remedial actions and imposes a prohibition on installation of non-Mod 3 actuators from the effective date. The AD’s text establishes the technical requirement and compliance timeline but does not specify specific monetary penalties, infringement notices, or criminal sanctions in the body of the AD itself.

Regulatory enforcement pathway (what the AD shows and what it does not)

• What the AD shows: CASA is the issuing authority and the AD is effective from 18 June 1998. The AD sets mandatory compliance steps and a compliance period. It cross-references FAA action as relevant context.

• What the AD does not show: The AD does not itself state the penalty regime or the procedural enforcement mechanisms that follow non-compliance, such as suspension of an operator’s certificate, grounding orders or pecuniary penalties. Those enforcement mechanisms, if any, would derive from the Civil Aviation Regulations and CASA’s enforcement policies and are outside the text of the AD provided.

Practical enforcement implications for operators

• Mandatory compliance: Practically, operators must document compliance (or a dispositioning action if applicable under CARs) to maintain the aircraft’s airworthiness status. An operator operating an aeroplane with an affected actuator that has not been modified by the compliance deadline would be operating a non-conforming aircraft under the AD’s terms.

• Installation control: The AD’s immediate prohibition on installing unmodified actuators shifts enforcement risk to maintenance actions. Certifying staff who install or sign for installation of an actuator that does not incorporate Mod 3 risk exposing the operator and maintenance provider to regulatory scrutiny for failing to follow an active AD.

• Supply-chain compliance enforcement: Suppliers and overhaul facilities holding stock of affected actuators that are not Mod 3-compliant must either update those items per the applicable maintenance manual or segregate and mark them to prevent installation on aircraft subject to the AD. If an operator inadvertently installs a non-Mod 3 actuator after the effective date, regulatory scrutiny will attach to both the operator and the maintenance provider.

Evidence and proof of compliance

• The AD’s language requires work “in accordance with procedures in the applicable maintenance manual.” Proof of compliance therefore relies on appropriate maintenance documentation: release-to-service certificates, logbook entries, and any modification records that show Mod 3 incorporation, together with serial-number traceability tying the replaced/installed actuator to an inventory record. The AD itself does not prescribe the exact documentary format.

Limits of conclusions from the AD text

• Because the AD does not enumerate specific enforcement sanctions, readers must consult the Civil Aviation Regulations 1998, Part 39 and CASA’s enforcement policies for precise enforcement actions and penalty regimes. The AD obliges action and establishes the compliance schedule; enforcement machinery and sanctions are set out elsewhere in the regulatory framework and are not stated in the AD text provided.

Relationship with Civil Aviation Regulations 1998

• Source authority: The AD is issued under the Commonwealth of Australia (Civil Aviation Regulations 1998), Part 39-107. The directive is thus a product of the CAR regulatory architecture. The AD’s mandatory nature and the compliance obligation flow from that legislative/regulatory grant of power.

Cross-reference to FAA AD

• The AD explicitly notes “FAA AD 98-08-20 Amdt 39-10469 refers.” That indicates a cross-jurisdictional alignment: CASA’s directive follows or mirrors an FAA directive addressing the same actuator failure mode. The AD’s background also cites FAA reports as the source of fault discovery (two reports of loose roll pins). This cross-reference means operators who operate internationally or in mixed-regulatory environments should be mindful of both CASA and FAA positions; however, the AD as issued by CASA is the operative Australian requirement.

Maintenance manual and continued airworthiness obligations

• The AD delegates the technical method to the “applicable maintenance manual.” That situates the AD within the broader regime that binds maintenance manual procedures as the technical standard for modifications. The maintenance manual is part of the continuing airworthiness framework; following it is part of an operator’s statutory obligations under the CARs to keep the aircraft in an airworthy condition.

Spares, parts and installations

• The AD’s installation prohibition interacts with laws and obligations regarding parts traceability, release-to-service procedures and maintenance releases. While the AD does not specify the paperwork, established regulatory practice is that any maintenance action must be recorded and certified. The prohibition will therefore affect how parts are stocked, sold and certified across the industry.

Contractual and commercial law interactions

• The AD creates obligations that cut across commercial relationships: aircraft lease agreements, sale contracts, maintenance contracts and warranties may specify which party bears the costs of compliance with ADs. The AD itself does not allocate cost; it imposes the compliance duty on the operator/owner as the party responsible for continued airworthiness under the CARs. Contractual allocation of the costs is therefore a matter for contract law and the parties’ agreements, not the AD text.

Insurance and liability interaction

• The AD addresses a mechanical failure mode that could cause loss of control. Insurers will view compliance (or non-compliance) with an active AD as central to risk assessments and claim handling. The AD’s effective date and compliance window create a clear benchmark against which insurers and courts could examine whether an operator met its continuing airworthiness duties; the AD text itself does not cover insurance consequences.

International operations

• Operators engaged in international operations need to reconcile CASA’s AD with foreign regulators’ directives (the AD itself references the FAA AD). The AD is the binding Australian regulatory instrument for Australian-registered aircraft or operations under CASA’s jurisdiction.

Text-provided history and effective date

• The AD text identifies a single issuance and effective date: “This airworthiness directive becomes effective on 18 June 1998.” No other amendments, supersessions, rescissions or variations are included in the text provided.

Cross-references and related instruments

• The AD explicitly notes that FAA AD 98-08-20 Amdt 39-10469 “refers.” That indicates an origin or parallel action by the FAA. The presence of the FAA reference indicates that Mod 3 and the safety rationale were also the subject of FAA action, but the AD does not reproduce the FAA AD text, nor does it indicate any amendment history resulting from that FAA action within Australia beyond the CASA AD itself.

Absence of subsequent amendments in the document

• The schedule entry contains no listed amendments, no re-issue dates, no errata and no superseding AD number. The AD should therefore be treated, from the text provided, as a standalone directive with one effective date and the specified requirements.

Implication for compliance tracking

• Because no amendment history is shown, operators must treat the AD as a live directive with the original effective date. In practice, operators should check CASA’s AD database and the Civil Aviation Regulations for any later revisions or superseding directives. The AD text itself contains no such update.

No litigation recorded in the text

• The AD document, as provided, contains no mention of litigation, appeals, judicial review, or dispute resolution arising from its issuance, interpretation or enforcement. The text includes the technical requirement, compliance timeline and background justification, but does not describe any legal challenges or court decisions.

How to interpret the absence

• The absence of litigation information in the AD does not mean disputes did not occur; it only means the instrument itself does not report any litigation. For an exhaustive litigation history, one would consult court records, administrative appeals to CASA, or other public records outside the AD. The AD text does not supply any case names, appeals outcomes or enforcement adjudications.

Operational relevance

• From a compliance standpoint, the absence of litigation detail in the AD means the directive’s obligations stand as written: replacement per Mod 3 and prohibition on non‑Mod 3 installations with the stated timing. Any operator assessing legal exposure must consider the CARs, general aviation regulatory enforcement mechanisms, and contractual obligations that could give rise to disputes , none of which are documented within this AD text.

Serial-number and part-number specificity

• The AD applies to part numbers 065-0076-10 through 065-0076-15 and serial numbers 0001 through 3081 inclusive. A common operational pitfall is misidentifying applicability by relying only on model designation or on an incomplete parts list. Operators must check part and serial numbers physically or via maintenance records. The AD’s applicability is defined by part and serial numbers, not solely by aircraft model.

Non-exhaustive aircraft listing

• The AD provides a list of aircraft where the actuators are “known to be fitted,” but explicitly states this list is not exhaustive. A common mistake would be to assume that absence of a particular aircraft model from the printed list means the operator is not affected. The controlling criterion remains part/serial match, regardless of aircraft model.

Immediate installation ban

• The AD’s Requirement 2 and Compliance item 2 impose an immediate prohibition on installing any actuator in the applicability statement that has not had Mod 3 incorporated “as of the effective date.” That means maintenance organisations cannot install unmodified spares from that date onwards. A trap for the unwary: spare-parts inventories must be audited and segregated to prevent inadvertent installation of non-Mod 3 parts.

100 hours TIS compliance window

• The replacement deadline is expressed as “within the next 100 hours time in service after the effective date.” Operators that track compliance by calendar time rather than flight hours risk missing the window. High-utilisation aircraft will reach 100 TIS quickly; low‑utilisation aircraft may take longer, but the compliance trigger is flight hours. Operators must plan maintenance scheduling to meet the 100-hour threshold.

Dependency on the “applicable maintenance manual”

• The AD requires that Mod 3 be incorporated “in accordance with procedures in the applicable maintenance manual.” If an operator or maintenance organisation lacks the correct revision of the maintenance manual, or if the manual’s instructions are unclear, that creates implementation risk. Failure to follow the maintenance manual’s exact procedure may render a Mod 3 work invalid for compliance purposes.

Spare parts and cannibalisation issues

• Removing the actuator for replacement and returning the aircraft to service with a spare requires that the spare be Mod 3-compliant. If an operator cannibalises a fleet for a Mod 3 unit, other aircraft may be left in non-compliance. The installation ban prohibits using non-Mod 3 parts on any aeroplane after the effective date, so cannibalisation creates cascading compliance problems unless all swaps are Mod 3-compliant.

Record-keeping and traceability

• Compliance proof will rest on accurate records linking serial numbers to modification statements. Gaps in serial-number traceability or incomplete maintenance documentation may create enforcement risk or grounding until the records can be remedied.

Supply constraints and scheduling pressure

• The AD’s short window (100 hours TIS) may generate demand spikes for Mod 3-compliant actuators or for authorised maintenance slots. That can cause scheduling pressure and potential grounding or restricted operations if operators cannot procure parts or maintenance capacity in time. The AD text does not provide transitional relief or extensions.

Potential interface with other required maintenance

• The AD does not preclude combining the Mod 3 replacement with other scheduled maintenance, but operators must ensure that combined work is performed and documented strictly per the applicable maintenance manual and regulatory requirements for release to service.

Interpretation of “replace” vs “modify”

• The AD’s wording is “Replace the autopilot servo actuator with an actuator that incorporates Mod 3.” That permits either replacing with a unit that already has Mod 3 incorporated or presumably performing the Mod 3 modification on an existing unit if the maintenance manual permits such a modification. Operators should confirm whether Mod 3 can be incorporated in the field or only at authorised repair facilities, and ensure release-to-service documentation reflects the final condition.

Step 0 , Immediate inventory and risk triage (Day 0 to Day 7)

• Identify affected units: Compile a parts and aircraft inventory listing every KSA‑470 actuator on the operator’s fleet, noting part number and serial number for each unit. The AD applies to part numbers 065-0076-10 through 065-0076-15 and serial numbers 0001-3081 inclusive.

• Segregate spares: Immediately segregate spare stock of the affected part numbers pending serial-number verification and Mod 3 status. Do not install any actuator from the applicability list unless Mod 3 incorporation is proven. The AD’s Compliance item 2 imposes a ban on installing non‑Mod 3 actuators “as of the effective date.”

• Identify high-utilisation aircraft: Prioritise aircraft likely to reach 100 hours TIS soon. The replacement deadline is “within the next 100 hours time in service after the effective date.”

Step 1 , Confirm maintenance manual procedure

• Obtain or confirm the latest “applicable maintenance manual” procedures for Mod 3. The AD mandates Mod 3 incorporation “in accordance with procedures in the applicable maintenance manual.” Ensure your approved maintenance organisation (AMO) or certifying engineer has the correct manual revision.

• Clarify whether Mod 3 is an in-situ modification or whether it requires replacement with a pre‑modified unit. The AD allows replacement “with an actuator that incorporates Mod 3” so either path should be validated against the maintenance manual and manufacturer guidance.

Step 2 , Logistics and procurement

• Assess parts availability: Contact OEMs, approved repair stations or authorised distributors for Mod 3-compliant actuators or for the parts and tooling necessary to perform Mod 3.

• Schedule maintenance slots: Given the 100-hour TIS window, plan maintenance downtime. For high-utilisation aircraft, urgency is higher. If multiple aircraft require work, prioritise by expected flight hours to the deadline.

• Contractual and cost allocation: Confirm who bears the cost under lease, purchase or maintenance contracts. The AD does not allocate cost; contractual arrangements will govern who pays for parts, labour and downtime.

Step 3 , Perform Mod 3 incorporation or replacement

• Use the applicable maintenance manual: Ensure every step follows the maintenance manual’s procedure to incorporate Mod 3. The AD conditions compliance on that manual.

• Certify the work: After completion, the authorised maintenance certifier must sign the appropriate release-to-service paperwork and make the entry required by the CARs, including serial numbers of the removed unit and of the unit installed/modified, and a statement that Mod 3 has been incorporated in accordance with the maintenance manual.

Step 4 , Record-keeping and parts control

• Update logbooks and records: Make explicit entries tying the Mod 3 incorporation to the actuator serial number, date, aircraft registration, and certifier identity. Retain manufacturer/repair-station paperwork that documents the Mod 3 work.

• Mark and segregate non-compliant stock: Any remaining non-Mod 3 spare parts should be labelled and segregated to prevent accidental installation. The AD prohibits installation of non-Mod 3 actuators after the effective date.

• Update maintenance tracking systems: Enter Mod 3 completion into aircraft maintenance tracking systems and notify relevant fleet managers and dispatch teams that the aircraft is compliant.

Step 5 , Verification and audit

• Internal audit: Run an internal audit to ensure no non‑Mod 3 actuators remain on aircraft or in ready spares intended for installations on aircraft subject to the AD.

• Cooperate with regulator if contacted: Retain documentation for regulatory inspection. Although the AD text does not list enforcement actions, CASA issued the directive; be prepared to demonstrate compliance.

Step 6 , Ongoing controls

• New purchases: Procure only Mod 3-compliant actuators or ensure any procured unmodified actuators are modified to Mod 3 prior to installation.

• Supplier contracts and warranties: Update purchase and repair contracts to require suppliers to deliver Mod 3-compliant units or to provide modification certification.

• Fleet policy: Adopt a fleet-wide policy preventing installation of non‑Mod 3 actuators and requiring traceability of serial numbers for all servo actuator replacements.

Suggested compliance checklist (practical)

1. Verify part number and serial number of installed actuator(s).
2. Confirm whether installed actuator already incorporates Mod 3 (document evidence).
3. If not Mod 3, schedule replacement/modification within 100 hours TIS of 18 June 1998.
4. Ensure maintenance action follows the applicable maintenance manual; retain procedure reference and revision number.
5. Record replacement/modification in aircraft logbook, include serial numbers and certifier identity.
6. Update parts inventory to show Mod 3 status; segregate or scrap non-compliant parts.
7. Notify operations and dispatch to avoid installing non-Mod 3 actuators.
8. Retain all supplier/repair documentation for regulatory review.

Practical notes on documenting Mod 3 incorporation

• The AD ties compliance to the maintenance manual. Certification should therefore include a statement that Mod 3 was incorporated “in accordance with the applicable maintenance manual” and identify the manual revision used.

• Where a replaced unit is returned to supplier or overhauled, maintain chain-of-custody documentation that shows the old unit’s serial number and the new/modified unit’s serial number, to preserve traceability.

• If the maintenance manual allows Mod 3 incorporation only at authorised repair stations, ensure those stations provide formal documentation that can be filed with the aircraft’s continuing airworthiness records.

Operational contingency planning

• If parts or authorised maintenance capacity are limited, consider temporary operational restrictions or prioritisation of aircraft that present higher safety risk or higher utilisation. Do not install non-Mod 3 actuators as that is prohibited as of the effective date.

• If uncertainty exists about an actuator’s Mod 3 status (for example ambiguous markings), treat the unit as non-modified until its history and certification can be verified.

Closing practical point

• The AD defines the technical fix (Mod 3) and the window for action (100 hours TIS), and it prohibits subsequent installation of non‑Mod 3 parts. Compliance therefore requires a coordinated effort across maintenance, parts procurement, records and operations to ensure timely, documented incorporation and to prevent inadvertent reintroduction of affected units.