AD/CESSNA 170/85 - Alternate Static Air Source Selector Valve Placard

This AD operates around a small set of technical and regulatory concepts. Each concept matters because the AD ties a compliance action, a deadline, or an operational prohibition to it.

Alternate static air source selector valve, port obstruction

• The physical object at issue is the alternate static air source selector valve. The problem is not a structural failure but an installation error: the part number identification placard on P/N 2013142-18 can obstruct the valve port. The AD repeatedly instructs inspection to "assure that the part number identification placard is not obstructing the port" (Requirements 1, 2a, 3). Where obstruction is found, the AD requires removal of the placard from the valve body, discard of the placard, and assurance the port is open and unobstructed (Requirement 4).

Applicability criteria and part numbers

• Applicability is model-specific and time-specific. The AD applies to the aeroplane models listed in Table 1. It then uses two overlapping criteria to pick up affected aeroplanes: those initially delivered from the manufacturer between 1 January 1993 and 31 March 2008, unless modified in accordance with AD/CESSNA 170/83; and aeroplanes that have had a P/N 2013142-18 installed as a replacement part at any time after 1 January 1993, unless the AD/CESSNA 170/83 modification/rework applies. Note 2 clarifies that P/N 2013142-18 replaced earlier P/Ns 2013142-9, -13, and -17, so owners must be alert to legacy part-number mappings when assessing applicability.

IFR equipment and temporary operational prohibition

• The AD distinguishes aeroplanes equipped for flight under instrument flight rules. For these aeroplanes the AD offers two choices. The first is an inspection within the short window of 10 days (Requirement 2a). The second is installation of a temporary cockpit placard before further flight, with prescribed words and minimum letter size, that prohibits IFR operation and use of the alternate static air source (Requirement 2b). If the temporary placard option is chosen, an inspection must follow and the temporary placard removed before further flight after inspection (Requirement 3).

Service bulletins as compliance procedures

• The AD specifies that "the procedures required to accomplish this AD are detailed in" named Cessna service bulletins appropriate to the model (Note 3). That ties the mandatory actions to manufacturer-published maintenance procedures, indicating the technical means by which inspections and removals should be conducted.

Compliance windows and sequence language

• The AD sets explicit compliance times. Requirement 1 and Requirement 3 call for inspection "within the next 100 hours time-in-service (TIS) after the effective date of this AD or within the next 4 months after the effective date of this AD, whichever occurs first." Requirement 2a must be done "within the next 10 days after the effective date of this AD." Requirement 2b must be done "before further flight" after the effective date. Requirement 4 must be completed "before further flight after the inspection required in Requirements 1, 2a, and 3 of this AD." Requirement 5 applies "as of 10 days after the effective date of this AD." These deadlines impose different operational constraints depending on whether the aeroplane is IFR-capable and which compliance path is chosen.

Supply-side constraint

• Requirement 5 effectively creates a supply control: "When a replacement valve is needed, only install a P/N 2013142-18 alternate static air source selector valve that has been inspected and the port is found free from obstruction." The AD sets that as the operative rule from 10 days after the effective date. This limits the pool of acceptable replacement parts to those that have been inspected.

Safety rationale

• The Background section, citing FAA findings, states the operational risk: erroneous indications on altimeter, airspeed, and vertical speed instruments could lead the pilot to respond to incorrect information and possibly lose control. CASA reports that the FAA found reports of aeroplanes with P/N 2013142-18 valves whose port was obstructed, and that CPD shipped these parts between 1 January 1993 and 31 March 2008 (Background, Note 1).

Interrelation with previous ADs and FAA action

• The AD explicitly links to prior regulatory actions. It references AD/CESSNA 170/83, which addressed related installation issues, and the FAA ADs (FAA AD 2008-10-02, and FAA AD 2008-26-10 as a referring document). The AD uses those references both to define exemptions ("unless the modification/rework required in AD/CESSNA 170/83 has been done and the aeroplane remains in compliance with that AD") and to adopt findings from the FAA (Background).

In short, the main concepts are a narrowly defined hardware obstruction risk linked to a particular part number series, a model-and-time-limited applicability, a short set of required inspections and placarding options for IFR capability, manufacturer service bulletins as the technical compliance pathway, and a post-deadline restriction on installing uninspected replacement valves.

The AD identifies and affects a discrete set of participants. The parties who bear the obligations or face operational limitations are listed below, with the concrete mechanism by which they are affected taken directly from the AD text.

Owners and operators of the aeroplane models listed in Table 1

• Owners and operators of the specific Cessna models in Table 1 must determine whether their aeroplane falls within the AD’s applicability window: delivered between 1 January 1993 and 31 March 2008, unless they have already completed the modification/rework required by AD/CESSNA 170/83 and remain in compliance with that AD; alternatively, if the aeroplane has a P/N 2013142-18 valve installed as a replacement at any time after 1 January 1993, they are also captured unless AD/CESSNA 170/83 applies (Applicability). Practically, this requires owners to review delivery records, maintenance logs, and parts-fitment history.

Pilots conducting IFR operations

• For aeroplanes equipped for IFR, pilots are directly affected because one compliance route is to install a visible cockpit placard that prohibits IFR operation and the use of the alternate static air source until inspection is completed and the placard removed (Requirement 2b; Requirement 3). That temporary placard must read specific words in a minimum letter size and be placed in the pilot’s clear view. The operational consequence can be immediate: IFR flight is explicitly prohibited while that placard is installed.

Maintenance organisations, licensed engineers and certifying staff

• Maintenance organisations must perform the inspections per the AD and per the Cessna service bulletins named in Note 3. They will need to remove and dispose of obstructing placards from valve bodies where found, and to certify that replacement P/N 2013142-18 valves have been inspected and are unobstructed before installation once the 10-day post-effective-date restriction is in force (Requirement 4; Requirement 5). They must also ensure the inspection timing requirements are met and documented for continuing airworthiness compliance.

Parts distributors and stockholders, including Cessna Parts Distribution

• The AD notes that "the affected part was shipped from Cessna Parts Distribution (CPD) between 1 January 1993 and 31 March 2008" (Note 1). That means parts distributors and spare parts stockholders must review their inventories for P/N 2013142-18 valves and the earlier P/Ns that were replaced by -18 (2013142-9, -13, -17). The AD’s Requirement 5 creates an immediate supply-side condition: after 10 days following effectiveness only inspected valves may be fitted. Distributors holding uninspected valves thus have to either inspect and certify them or restrict their sale for installation.

Civil Aviation Safety Authority and regulators

• CASA is the issuing authority here, and the AD references FAA actions. CASA’s statement, "CASA has no way of determining which aeroplanes have the remaining problem alternate static air source selector valve assemblies installed without having all of the affected aeroplanes and spares stock inspected," indicates the regulator expects the affected parties to undertake inspections and report or record compliance (Background).

Operators with mixed fleets and clubs

• Operators that manage fleets, aero clubs, flying schools, and rental operations where IFR capability may be intermittently required must segregate aircraft by compliance status. Some aeroplanes in a mixed fleet may require immediate placarding, which reduces fleet availability for IFR flights, while others may be cleared. The AD’s compliance intervals and the 10-day restriction on installing replacement valves will be operational constraints.

Insurance and safety-management stakeholders

• Although not named in the AD, insurance underwriters and safety managers are affected in practice because the AD creates a documented risk and a regulatory compliance obligation. Failure to comply would be visible in maintenance records and could affect insurance coverage or safety assessments, though the AD text itself does not speak to insurance.

In sum, the AD affects aircraft owners/operators, IFR pilots, maintenance organisations, parts distributors and stockholders, and, indirectly, entities concerned with operational availability and safety oversight. The AD’s mechanism is that it imposes mandatory inspections, temporary operational prohibitions for IFR aircraft where chosen, disposal requirements, and a placed-based restriction on installing uninspected replacement valves.

The AD specifies a set of mandatory duties, precise compliance windows, and limited operational options for affected aeroplanes. The text itself sets duties but does not enumerate rights beyond the ability to choose between compliance paths for IFR aircraft. Each duty in the AD carries a specific timing constraint.

Primary duties

• Inspect the alternate static air source selector valve to ensure the part number identification placard is not obstructing the port. This inspection duty applies to "all affected aeroplanes that are not equipped for flight under IFR" (Requirement 1) and to IFR-equipped aeroplanes under Requirement 2a, and again where temporary placards have been used under Requirement 3. The AD prescribes different timing for these inspections depending on IFR capability: for non-IFR aircraft the inspection is to be done "within the next 100 hours time-in-service (TIS) after the effective date of this AD or within the next 4 months after the effective date of this AD, whichever occurs first" (Compliance for Requirement 1). For IFR a/c electing to inspect rather than placard, Requirement 2a requires inspection "within the next 10 days after the effective date of this AD" (Compliance for Requirement 2a).

• For IFR aircraft that cannot complete the inspection within the 10-day window, the AD allows an alternative but it is a strict operational prohibition: fabricate and install a placard that states "IFR OPERATION IS PROHIBITED" and "USE OF THE ALTERNATE STATIC AIR SOURCE IS PROHIBITED" in at least 1/8-inch letters in the pilot’s clear view, before further flight (Requirement 2b; Compliance for Requirement 2b). If an operator fits this placard, they must still perform the inspection under Requirement 3 within the general 100 hours or 4 months window, and remove the temporary placard before further flight after the inspection (Requirement 3).

• Where the inspection reveals the part number identification placard is obstructing the valve port, the AD requires removal of the placard from the valve body, discarding of the placard, and assurance the port is open and unobstructed (Requirement 4). Requirement 4 must be completed "before further flight after the inspection required in Requirements 1, 2a, and 3 of this AD" (Compliance for Requirement 4). That creates a pre-flight remediation duty.

• When a replacement valve is needed, only install a P/N 2013142-18 valve that has been inspected and its port found free from obstruction, effective as of 10 days after the AD's effective date (Requirement 5; Compliance for Requirement 5). This creates a forward-looking procurement duty: maintenance personnel must verify inspection status before installing the part.

Procedural duty imposed by service bulletins

• The AD instructs that "the procedures required to accomplish this AD are detailed in" specific Cessna service bulletins (Note 3). That places a duty on maintainers to use the manufacturer’s published procedures when carrying out the inspections and removals the AD mandates.

Documentary duties (implicit)

• While the AD text does not itemise record-keeping obligations beyond the completion of the tasks, typical airworthiness directive practice requires maintenance entries and logbook notations to show compliance. The AD’s deadlines and the Requirement 5 prohibition imply an operator must be able to demonstrate inspection of replacement valves prior to installation. The AD itself does not state the exact documentation format.

Choices the AD allows

• The AD offers one explicit choice for IFR-equipped aeroplanes: either inspect within 10 days (Requirement 2a) or install the prohibition placard and delay IFR operation until the inspection is completed and the placard removed (Requirement 2b and Requirement 3). This is the only operational choice the AD provides.

Limitations and prohibitions

• The AD prohibits installation of P/N 2013142-18 valves that have not been inspected and found unobstructed, from 10 days after the effective date (Requirement 5). That sets a prospective procurement prohibition, which affects parts supply and maintenance planning.

No affirmative entitlement to exemptions stated

• The AD does not provide a mechanism within its text for alternative means of compliance or for exemptions. It instead ties procedures to the Cessna service bulletins, which are referenced as the procedures for accomplishing the AD (Note 3). If operators seek alternative means, the AD text does not specify the route, so they would be dependent on CASA's usual administrative processes outside the AD text. The AD itself does not set out such a process.

Taken together, the AD establishes inspection, placarding, removal, disposal, and procurement duties with explicit timing, offers a single conditional operational choice for IFR aircraft, and ties technical compliance to manufacturer service bulletins. The AD text does not specify penalties, alternative means of compliance within the AD, or detailed record-keeping formats.

The AD text itself sets mandatory technical and timing requirements, but it does not set out specific monetary penalties, criminal sanctions, or an enforcement procedure within its own wording. The document contains the directive language necessary to obligate operators who fall within its applicability to carry out inspections, remove and discard obstructing placards, install temporary placards where prescribed, and restrict installation of uninspected replacement valves, with explicit compliance timelines. The AD states effective dates and compliance windows, for example "This Airworthiness Directive becomes effective on 16 January 2009" and the various compliance timing provisions for Requirements 1 through 5.

What the AD text does not do, and what therefore must be noted, is explicitly state enforcement mechanisms or penalties. There is no clause in the AD document that specifies fines, licence suspensions, administrative penalties, or criminal liability. The AD does, however, create clear mandatory actions and deadlines which CASA expects to be followed; an AD by its nature embeds regulatory obligations under the Civil Aviation regulatory framework, and failure to comply would be a regulatory non-compliance matter under that broader regime. The AD notes CASA’s inability to determine which aeroplanes or stock are affected without inspection, implying that compliance and inspection actions are the means by which CASA will collect evidence that the condition has been addressed (Background).

Practically, enforcement of ADs in civil aviation is carried out by the regulator through its standard compliance and enforcement mechanisms, which can include audits, notices, and, where applicable, regulatory sanctions under the enabling civil aviation legislation and regulations. The AD does not itself set those mechanisms out. Therefore, operators and maintenance organisations should assume that the AD is mandatory and that failure to meet the requirements could attract attention from the regulator and possible enforcement action, but the AD text does not enumerate the specific penalties or enforcement pathways.

The AD references FAA actions (FAA AD 2008-10-02 and FAA AD 2008-26-10) and the prior CASA AD/CESSNA 170/83. Those references indicate the AD is part of a coordinated set of airworthiness obligations across jurisdictions. Enforcement may therefore be relevant to cross-border maintenance or recognition of maintenance work done abroad, but the AD text does not detail extra-territorial enforcement procedures.

In short, the document mandates action, sets deadlines and operational limitations, but does not itself specify penalties or enforcement steps; readers must look to CASA’s broader regulatory framework for the specific enforcement modalities that would apply to non-compliance.

The AD explicitly interacts with other airworthiness directives, manufacturer service bulletins, and with FAA regulatory actions. The AD constructs its applicability and technical compliance pathway by cross-reference.

Relationship with previous CASA AD/CESSNA 170/83

• The AD conditions applicability on whether the modification/rework required in AD/CESSNA 170/83 has been done and the aeroplane "remains in compliance with that AD" (Applicability). That interaction means that aircraft which already complied with AD/CESSNA 170/83 and continue to meet its requirements are exempt from these new obligations insofar as the AD is aimed at parts/assemblies addressed by the previous AD. The AD does not reproduce AD/CESSNA 170/83, so operators must consult that earlier AD to determine whether they are exempt. This creates a direct interdependence: compliance status under AD/CESSNA 170/83 affects applicability here.

Reference to FAA ADs

• The AD cites FAA AD 2008-10-02 as the initial trigger for AD/CESSNA 170/83 and references FAA AD 2008-26-10 as a document that "refers" (Note 3). The Background section records the FAA’s reports of affected aeroplanes and spares stock. These cross-references indicate that CASA’s AD is part of an international safety response to a common technical fault, and they provide the evidentiary basis for CASA’s intervention. For operators, work done to comply with the FAA ADs or information derived from those FAA ADs will be relevant to assessing compliance. The AD therefore sits in a landscape of internationally coordinated airworthiness measures.

Manufacturer service bulletins as required procedures

• The AD does not provide step-by-step technical instructions in the AD text itself; instead it requires use of specific Cessna service bulletins for the procedures to accomplish the AD (Note 3). This makes the technical compliance pathway dependent on manufacturer documentation. From a legal perspective, the AD therefore operates by mandating adherence to private-sector technical standards, bringing manufacturer procedure documents into regulatory force for the purpose of this AD.

Parts supply rules and prior part numbers

• The AD notes that P/N 2013142-18 replaced P/Ns 2013142-9, -13, and -17 (Note 2), and that the affected part was shipped by CPD between specified dates (Note 1). That means parts stock acquired under earlier part numbers may have been superseded and are relevant to compliance. It also imposes a future constraint on installation of P/N 2013142-18 unless inspected (Requirement 5), which interacts with procurement law and contract fulfilment for maintenance providers, in that contracts for parts and maintenance must now incorporate the inspection status of replacement valves.

Interaction with maintenance certification and airworthiness records

• The AD imposes duties that must be reflected in maintenance actions. Although it does not itself spell out recordkeeping or certification formats, the requirement to perform inspections, to remove placards, and to only install inspected replacement valves means the maintenance release or logbook entries must reflect compliance. Those entries interact with statutory obligations about maintenance release documents and continuing airworthiness records, which sit in aviation regulation outside the AD.

No stated conflicts with other laws in the AD text

• The AD does not identify or resolve any potential conflicts with other laws or regulations. It neither cancels nor amends other ADs except by reference, and it conditions applicability on compliance with AD/CESSNA 170/83. Operators should therefore plan compliance with this AD while respecting the parallel obligations of other ADs, service bulletins, and national maintenance regulations.

Overall, this AD is not standalone. It ties directly to prior CASA and FAA ADs and to Cessna service bulletins. The practical effect is that compliance requires engaging with manufacturer technical procedures and with the recordkeeping and enforcement structures of civil aviation regulation.

The AD text itself contains only limited amendment-related material that is directly relevant. The document is dated 8 January 2009 and states that "This Airworthiness Directive becomes effective on 16 January 2009." It also contains explicit references to earlier airworthiness actions and to the FAA ADs that informed the CASA action. The relevant history and references set out in the AD are:

• AD issuance and effective date

  • Signed: James Coyne, Delegate of the Civil Aviation Safety Authority, 8 January 2009.
  • Effective: "This Airworthiness Directive becomes effective on 16 January 2009."

• Related CASA AD

  • AD/CESSNA 170/83 is referenced twice, first as the earlier AD issued in response to FAA AD 2008-10-02 and second as an exemption clause, "unless the modification/rework required in AD/CESSNA 170/83 has been done and the aeroplane remains in compliance with that AD" (Applicability). AD/CESSNA 170/83 therefore forms part of the amendment chain; AD/CESSNA 170/85 applies only where AD/CESSNA 170/83 is not in effect or has not been complied with.

• FAA ADs referenced

  • FAA AD 2008-10-02 is identified as the trigger for AD/CESSNA 170/83 in the Background.
  • FAA AD 2008-26-10 Amdt 39-15776 dated 15 December 2008 is referenced in Note 3 as a referring document. The AD describes FAA reporting and follow-up that led CASA to issue AD/CESSNA 170/85.

• Manufacturer service bulletins

  • The AD references the procedures required to accomplish the AD as detailed in:
    • Cessna Single Engine Service Bulletin SB08-34-02, Revision 1, dated 6 October 2008;
    • Cessna Caravan Service Bulletin CAB08-04, Revision 1, dated 6 October 2008;
    • Cessna Single Engine Service Bulletin SEB08-5, dated 13 October 2008;
    • Cessna Multi-engine Service Bulletin MEB08-6, dated 13 October 2008.
  • The AD requires compliance with these service bulletins "as applicable" and thereby integrates them into the AD’s enforcement of corrective procedures.

• No subsequent amendments recorded in the AD text

  • The AD document provided does not include any recorded amendments to AD/CESSNA 170/85 itself beyond the issuance and the embedded references to other ADs. There is no text in the AD indicating that it amends, replaces, or is superseded by another CASA action within the document. If operators need to know whether this AD was subsequently amended, superseded, or revoked, they must check CASA’s official AD register or other official publications for updates beyond this AD text.

• Notes clarifying part numbers and shipments

  • Note 1 states that the affected part was shipped from Cessna Parts Distribution between 1 January 1993 and 31 March 2008.
  • Note 2 states that P/N 2013142-18 replaced earlier part numbers 2013142-9, -13, and -17.

In practice, the amendment history relevant to users of this AD includes the preceding CASA AD/CESSNA 170/83, the FAA ADs that led to that earlier CASA AD and to the FAA follow-up, and the manufacturer service bulletins that provide the technical procedures. The AD itself records those cross-references but does not set out any later revisions or amendments to AD/CESSNA 170/85 in this text.

The AD text contains no litigation history. It does not reference any judicial decisions, complaints, judicial reviews, or court proceedings arising from AD/CESSNA 170/85 or from the related FAA ADs and CASA AD/CESSNA 170/83. The document is a regulatory instrument and its text is limited to the safety problem, the affected models and parts, the required inspections and remedial actions, and the service bulletins to be followed.

Because the AD is a regulatory instrument and does not itself record litigation, practitioners seeking litigation history or precedential court rulings that interpret, challenge, or enforce AD/CESSNA 170/85 must consult external sources: court registries, administrative law decisions, and CASA enforcement records. The AD text does not indicate whether any such challenges exist.

Given that the AD cross-references FAA actions, any litigation that arose from those FAA ADs would not be recorded in this CASA AD text, and again would need to be located outside this document. The AD does note that the FAA received reports of 15 aeroplanes "not previously affected by AD 2008-10-02" with obstructing P/N identification placards, and that the FAA informed that all P/N 2013142-18 valves shipped by CPD between specified dates "may have port obstruction." Those are factual statements in the Background section, not indications of litigation.

For practitioners, the absence of litigation history in the AD means that any legal questions about enforcement, interpretation of the AD’s applicability clauses, or disputes over compliance practices have no precedential treatment contained in the AD itself. Any such disputes would have to be researched in external case law or administrative decisions.

The AD contains a number of details and phrasing points that can create practical traps for operators, maintenance organisations, and parts suppliers. These are not legal opinions, but concrete implementation points drawn from the AD text that commonly trip up operators.

Applicability is model-specific and date-specific, and tied to a prior AD

• The AD applies only to the aeroplane models listed in Table 1. But that is not the end of the test. The AD applies to those models if they were "initially delivered from the manufacturer between 1 January 1993, and 31 March 2008, unless the modification/rework required in AD/CESSNA 170/83 has been done and the aeroplane remains in compliance with that AD; or have a P/N 2013142-18 installed as a replacement part anytime after 1 January 1993, unless the modification/rework required in AD/CESSNA 170/83 has been done and the aeroplane remains in compliance with that AD" (Applicability). Practically, that means operators must check both delivery dates and maintenance/parts-fit history and confirm whether AD/CESSNA 170/83 modification/rework has been done, and whether compliance with that AD has been maintained.

Spare parts stock and older part numbers

• Note 2 states that P/N 2013142-18 replaced P/Ns 2013142-9, -13, and -17. That means that parts recorded under older part numbers could be present in stock or already installed. The AD’s Requirement 5 limits installation of P/N 2013142-18 unless inspected, but it does not explicitly say how to treat earlier part numbers that were superseded. Operators should not assume that an earlier P/N is safe; rather they must confirm whether the valve assembly installed is one of the affected assemblies and whether its placard obstructs the port.

IFR placard sequence trap

• For IFR-equipped aeroplanes, Requirement 2b allows installation of a placard that reads "IFR OPERATION IS PROHIBITED" and "USE OF THE ALTERNATE STATIC AIR SOURCE IS PROHIBITED" in at least 1/8-inch letters, to be installed "on the instrument panel within the pilot’s clear view." The AD also requires, if placards were installed in accordance with Requirement 2b, that the valve be inspected and, "After doing the inspection, remove the placards installed in accordance with Requirement 2b of this AD before further flight" (Requirement 3). Operators must get the sequencing right: installation of the placard is a temporary measure to allow continued flight under VFR, but the placard must be removed after the inspection before flying again. Failure to remove or to sequence inspection and removal properly could result in an aircraft being operated contrary to the placarded limitation.

Differing compliance deadlines, "whichever occurs first"

• Requirements 1 and 3 use the phrasing "within the next 100 hours time-in-service (TIS) after the effective date of this AD or within the next 4 months after the effective date of this AD, whichever occurs first." This phrasing creates a sooner deadline depending on an aircraft’s utilisation. High-utilisation aircraft might hit 100 TIS in less than 4 months, pulling the deadline earlier. Operators must not rely solely on calendar time.

Replacement valve installation restriction

• Requirement 5 states, "When a replacement valve is needed, only install a P/N 2013142-18 alternate static air source selector valve that has been inspected and the port is found free from obstruction." The compliance timing for Requirement 5 is "As of 10 days after the effective date of this AD." That means that after that date a replacement P/N 2013142-18 cannot be installed unless it has been inspected. Stock that is held by parts shops or maintenance providers but not inspected cannot be fitted, which could create a sudden supply bottleneck for operators needing urgent repairs unless they ensure inspected spares are available.

Procedures mandatory but external

• The AD requires following Cessna service bulletins for the necessary procedures (Note 3). That is practically sensible, but it means that operators must have access to, and correctly apply, manufacturer service bulletins. The AD does not include the technical steps inside the AD text, so failure to follow the exact service bulletin procedure could lead to non-compliance.

CASA’s inability to identify affected units

• The AD states that "CASA has no way of determining which aeroplanes have the remaining problem ... without having all of the affected aeroplanes and spares stock inspected." That creates a diffuse compliance burden: every operator and stockholder must assume possible impact and inspect. Do not assume a part is fine simply because it came from a certain source; check.

Exact placard wording and minimum letter size

• The AD prescribes exact wording for the temporary IFR prohibition placard and a minimum letter size "at least 1/8-inch letters." Failure to use the exact wording or to meet the letter-size requirement could be construed as non-compliant.

Ambiguity about alternate means of compliance or variations

• The AD does not set out a route for alternative means of compliance within its text, nor does it provide examples of acceptable inspection evidence. Practitioners seeking to implement alternative inspection techniques or documentation should be aware they will need to consult CASA for formal acceptance as the AD text does not provide it.

No penalties within the AD text

• The AD contains no specific penalties, and does not detail enforcement mechanisms, so operators might mistakenly assume a breach has no consequence. In reality, the AD is a regulatory obligation and non-compliance will be a matter for the regulator, even though the AD does not state the sanction framework.

In short, the "gotchas" are concentrated around applicability checks, spare inventory, timing sequencing especially for IFR aircraft, precise placard text and size, and the requirement to use manufacturer service bulletins. Each of these is expressly stated in the AD text and can cause operational disruption if not handled deliberately.

The AD specifies discrete technical tasks, compliance deadlines, and referenced procedures. The following is a practical, stepwise compliance checklist grounded in the AD text that an operator or maintenance organisation can follow. It assumes the reader will consult the AD and the Cessna service bulletin appropriate to their aeroplane model for the detailed technical steps.

1. Determine applicability

• Consult Table 1 in the AD and identify whether your aeroplane model is listed. Confirm the aircraft’s initial delivery date from manufacturer records. If the aeroplane was initially delivered between 1 January 1993 and 31 March 2008, the AD applies unless the modification/rework required by AD/CESSNA 170/83 has been done and the aircraft remains in compliance with that AD.
• If the aircraft had a replacement alternate static air source selector valve fitted since 1 January 1993, check the replacement part number. If a P/N 2013142-18 valve has been installed as a replacement part anytime after 1 January 1993, the AD applies unless AD/CESSNA 170/83 modification/rework and continued compliance exists.
• Inspect maintenance records to confirm whether AD/CESSNA 170/83 was complied with and whether the aircraft remains in compliance with that AD.

2. Inventory spares and parts stock

• Inspect spare parts holdings and component inventories for P/N 2013142-18 and for the older P/Ns 2013142-9, -13, -17 which were superseded by -18 (Note 2). Treat all such spares as potentially affected unless they have been inspected and the port found unobstructed.

3. Choose the compliance path if IFR-equipped

• If the aeroplane is equipped for IFR flight choose between:
  • Requirement 2a: Inspect the alternate static air source selector valve to ensure the part number identification placard is not obstructing the port, to be done "within the next 10 days after the effective date of this AD."
  • Requirement 2b: Fabricate and install a temporary cockpit placard that states, in at least 1/8-inch letters, "IFR OPERATION IS PROHIBITED" and "USE OF THE ALTERNATE STATIC AIR SOURCE IS PROHIBITED," installed on the instrument panel within the pilot’s clear view, to be done "before further flight after the effective date of this AD." If this temporary placard is installed, the inspection per Requirement 3 must still be performed within the 100 TIS or 4-month window and the temporary placard must be removed after the inspection and before further flight.

4. Timing for non-IFR-equipped aeroplanes

• For aeroplanes not equipped for IFR, perform the inspection required in Requirement 1 "within the next 100 hours TIS after the effective date of this AD or within the next 4 months after the effective date of this AD, whichever occurs first."

5. Perform the inspection per the Cessna service bulletin

• Use the applicable Cessna service bulletin procedures: Single Engine SB08-34-02 Rev 1 (6 Oct 2008), Caravan CAB08-04 Rev 1 (6 Oct 2008), SEB08-5 (13 Oct 2008), or MEB08-6 (13 Oct 2008), as relevant to the model (Note 3). Follow the SB's detailed steps for disassembly, inspection of the valve body, removal of placards, and reassembly.

6. If obstruction is found

• If the inspection reveals the part number identification placard obstructs the valve port, remove the placard from the valve body, discard the placard, and ensure the port is open and unobstructed (Requirement 4). Do not return the aircraft to flight with an obstructed port; Requirement 4 is to be completed "before further flight after the inspection."

7. Replacement valve policy

• From 10 days after the AD’s effective date forward, when a replacement P/N 2013142-18 valve is needed, only install a valve that has been inspected and for which the port has been found unobstructed (Requirement 5). Maintain evidence of that inspection for the specific part being installed.

8. Record keeping and maintenance release

• Document the inspection in the aircraft maintenance records and logbook entries. Record the part numbers inspected, the inspection date, the inspector/organisation, and the outcome (port unobstructed or placard removed and discarded). If a temporary placard was installed for IFR mitigation, document its installation and subsequent removal after the inspection.

9. Spare and procurement management

• Segregate uninspected P/N 2013142-18 valves in stock until inspected. For any incoming P/N 2013142-18 valves acquired after the effective date, confirm and document their inspection status before installation. Update procurement processes to require inspection verification for P/N 2013142-18 prior to acceptance for fitment.

10. Operational controls

• For aircraft that have been placarded under Requirement 2b, implement procedural controls to prevent inadvertent IFR flight while the placard is installed, and maintain documentation proving the placard’s removal occurred only after inspection and rectification.

11. Communication with regulators and customers

• If you are a maintenance organisation or parts distributor, proactively notify affected customers/operators holding the models in Table 1 and those with spare stock of the required inspection obligations and the Requirement 5 restriction on installation of P/N 2013142-18 without inspection.

12. Follow-up and audit

• Given CASA’s statement that it cannot determine which aircraft and spares are affected without inspection, consider internal audits to ensure all affected assets have been checked and records are kept, to demonstrate compliance in future regulatory checks.

13. Consult CASA for uncertainties

• The AD itself does not specify alternative means of compliance within its text. If an operator wishes to pursue an alternative compliance method, or needs clarification on documentation or inspection acceptance criteria beyond the Cessna service bulletins, consult CASA for formal guidance, recognising the AD requires the procedures detailed in the named service bulletins.

By following the sequence above, and by keeping documentary proof aligned to each Requirement and its compliance timing, operators can demonstrate they have complied with the AD’s obligations. The AD ties the technical steps to manufacturer service bulletins and sets firm deadlines that are functionally enforceable under the civil aviation regulatory regime outside the AD text.