AD/CESSNA 170/83 - Alternate Static Air Source Valve

The directive implements several linked technical and administrative concepts that determine its reach and practical effect.

• Applicability defined by model and serial numbers. The AD uses two tables: Table 1 lists specific serial numbers of models that had the affected valve installed during manufacture and therefore require the physical inspection set out in Requirement 1; Table 2 lists a broader range of models and serial numbers that "could have had the affected part installed as a replacement part or from parts held as spares" and for which operators may either perform the physical inspection or check maintenance records to ascertain whether P/N 2013142-18 was fitted since 19 November 2007 (Table 1; Table 2).

• Focus on a single component fault mode. The technical failure mode is an identification placard placed over the valve's forward port, which is the inlet for static air reference to the alternate static air source selector valve. The placard obstructs the port, and this obstruction can cause erroneous readings from altimeter, airspeed and vertical speed instruments (Background). The AD therefore targets the port's accessibility and unobstructed status.

• Simple inspection protocol. Requirement 1 specifies how to inspect when physical inspection is required: seat adjustment (pilot and copilot seats as far aft as possible), then use of a flashlight and mirror to inspect that the forward port is clearly visible and not covered by the identification placard (Requirement 1.a and 1.b). Those procedural steps are part of the defined, minimum inspection method.

• Two compliance paths for some aircraft. For aircraft in Table 2, operators may either perform the physical inspection per Requirement 1 or inspect maintenance records to determine whether a P/N 2013142-18 valve has been fitted since 19 November 2007, in which case no further action is necessary if the valve has not been replaced (Requirement 2.a, 2.b; Requirement 3). Note 3 expressly allows the aeroplane operator who holds at least a private pilot’s licence to accomplish and certify the Requirement 2.b records inspection and determination.

• Pre-installation control over parts. Requirement 5 extends the control upstream: any P/N 2013142-18 valve installed as a modification or replacement part on or after the effective date must be inspected in accordance with Requirement 1 prior to installation. This introduces a supply-chain or installation gate for that part number.

• Temporal stringency. Compliance timings are immediate: Requirements 1-3 must be completed before further flight after the AD’s effective date; the placard removal in Requirement 4 must be completed before further flight after the Requirement 1 inspection; and Requirement 5 is effective "as of the effective date" (Compliance; Requirement 4; Requirement 5). The AD thus imposes immediate grounding until the minimal inspection is completed.

• Cross-reference to FAA AD and manufacturer actions. The AD notes the FAA AD 2008-10-02 and records that Cessna corrected parts held in stock but cannot verify how many affected assemblies were shipped to customers (Background; Note 4). CASA indicated it could not determine which aeroplanes had affected valves without inspection (Background). CASA also "varied the inspection requirements to allow the aeroplane operator to determine if a P/N 2013142-18 selector valve has been installed since 19 November 2007" (last paragraph of Background). That is the explicit policy divergence from the FAA AD manifested in the two-path approach for Table 2 aircraft.

The AD identifies affected parties precisely by reference to aircraft model and serial numbers, and by reference to the specific part number P/N 2013142-18. Practically, those who must act are:

• Owners and operators of Cessna 170, 172, F172, FR172 and 175 series aeroplanes listed in Table 1 and Table 2. Table 1 identifies a narrow set of serial numbers for which the affected valve was installed at manufacture and inspection is mandatory. Table 2 lists a broader set of model/serial combinations "that could have had the affected part installed as a replacement part or from parts held as spares" (Table 1; Table 2). The AD covers many sub-models (for example 172, 172R, 172S, F172 variants, FR172 variants, R172, P172, 172RG, etc.) and for several entries specifies "All S/Ns", while for others it provides serial ranges (Tables).

• Maintenance organisations, engineers and persons who install parts. Requirement 5 requires that any P/N 2013142-18 valve "installed as modification or replacement parts on or after the effective date of this Directive must be inspected in accordance with Requirement 1 prior to installation." This affects organisations that supply, store, or fit those parts.

• Aeroplane operators with at least a private pilot's licence. Note 3 permits the aeroplane operator, provided they hold at least a private pilot’s licence, to accomplish and certify the Requirement 2.b inspection of maintenance records. That allows certain operators to self-determine whether a stock or replacement part was fitted since 19 November 2007 without requiring a maintenance engineer to perform the records check.

• Regulators and delegates. CASA issued and delegated the AD (signed by James Coyne, Delegate of CASA). CASA is the issuer and custodian of compliance timing and any regulatory follow-up implied by the AD (signature and Background statements).

• Supply-chain entities that hold parts stocks. The Background states Cessna corrected parts in stock but could not verify how many assemblies left the factory with the placard improperly placed; CASA likewise cannot determine which aircraft have the valves without inspection. That places the burden on anyone holding spare parts or assemblies of P/N 2013142-18 to ensure they are inspected before installation (Requirement 5).

Who does not have to act: aircraft and parts not listed in the applicability Tables and parts that are not P/N 2013142-18 are outside the AD. But Table 2’s breadth means that many registrations are captured by the "All S/Ns" entries; operators must check the particular model/serial combinations to confirm applicability.

Concrete practical effects on affected parties: immediate grounding until inspection is completed (compliance for Requirements 1-3 is "Before further flight after the effective date"); possible removal and disposal of identification placards; potential administrative work to document the inspection or the maintenance-records check; and changes to installation practice (pre-installation inspection for P/N 2013142-18 parts fitted on/after the effective date).

The AD spells out discrete duties and one expressly stated conditional right (to self-certify the records check) for operators.

Duties

• Mandatory inspection for Table 1 aircraft. For aeroplanes listed in Table 1 the duty is to perform the physical inspection of the alternate static air source selector valve to "assure that the part number identification placard is not obstructing the port" by following Requirement 1, which prescribes seat adjustment and the use of a flashlight and mirror to view the forward port (Requirement 1; Requirement 1.a-1.b). Compliance timing: before further flight after the effective date (Compliance).

• Inspection or records-check for Table 2 aircraft. For aeroplanes in Table 2 the duty is either to perform the physical inspection in accordance with Requirement 1 (Requirement 2.a) or to inspect maintenance records to determine whether a P/N 2013142-18 valve has been fitted since 19 November 2007, in which case no further action is necessary if no such replacement has been made (Requirement 2.b). Compliance timing: before further flight after the effective date (Compliance).

• Further inspection triggered by records-check. If the records-check under Requirement 2.b shows that a P/N 2013142-18 valve has been installed, the operator must then inspect the valve in accordance with Requirement 1 (Requirement 3).

• Removal of obstructing placard. If, during any Requirement 1 inspection, the port is found obstructed by the part number identification placard, the placard must be removed from the valve body, discarded and it must be assured that the port is open and unobstructed (Requirement 4). Compliance timing: before further flight after the Requirement 1 inspection (Compliance).

• Pre-installation inspection obligation. Requirement 5 requires that any P/N 2013142-18 selector valves installed as modification or replacement parts on or after the effective date of the Directive must be inspected in accordance with Requirement 1 prior to installation. That effectively places a mandatory inspection gate on installations of that P/N after the AD's effective date (Requirement 5).

• Timings: Immediate. For Requirements 1, 2 and 3 the AD is explicit that they must be done "Before further flight after the effective date of this Directive." For Requirement 4, "Before further flight after the Requirement 1 inspection." For Requirement 5, the action is required "As of the effective date of this Directive" (Compliance; Requirement 4; Requirement 5).

Rights / permissions expressly in the text

• Limited operator self-certification. Note 3 permits the aeroplane operator to perform and certify the Requirement 2.b records inspection "provided that they hold at least a private pilot’s licence." That is a right to self-accomplish and certify the maintenance-records determination without requiring a maintenance engineer or similar holder of a higher maintenance authority to do it. The AD does not extend a similar right to physical inspection under Requirement 1; Requirement 1 prescribes inspection method but does not specify who must perform it.

Matters not specified in the AD (practitioner attention required)

• The AD does not specify the precise form or content of the certification or logbook entry required to record that an inspection/disposal has been performed. It prescribes the action and who may perform one type of records check but leaves standard maintenance recording practice to be applied.

• There are no explicit penalties, enforcement steps, or compliance audit mechanisms described within the AD text itself (no fines, sanctions or enforcement process are set out in this Directive text). The AD sets mandatory actions and timings, and the document is issued by a CASA delegate; regulatory enforcement mechanisms would reside in CASA’s broader airworthiness enforcement powers, but those are not detailed in the AD.

Operational consequences of the duties

• Aircraft affected by the AD and not yet inspected are grounded for "further flight" until the relevant inspection or records check is completed (Compliance). The burden falls on operators to perform immediate checks or to determine status through maintenance records; if an obstructing placard is found, the valve must have the placard removed and port cleared before further flight (Requirement 4). Operators fitting P/N 2013142-18 parts must build the inspection step into installation workflows (Requirement 5).

The Directive itself sets mandatory technical and timing obligations but does not set out explicit statutory penalties, nor does it articulate an enforcement regime within the text provided. The document is an Airworthiness Directive issued by the Civil Aviation Safety Authority (CASA), signed by James Coyne, Delegate of CASA, and it prescribes actions and deadlines (including immediate "Before further flight" timings). The AD therefore functions as a mandatory regulatory instrument within CASA’s airworthiness framework; however, the AD text contains no section that specifies fines, de-registration, or criminal penalties within the Directive itself.

What the AD does specify, and which bears on enforcement practice, is:

• Mandatory actions and short compliance windows. Requirements 1-4 impose immediate "Before further flight" obligations and Requirement 5 imposes a continuing pre-installation inspection duty for P/N 2013142-18 parts installed on/after the effective date (Compliance; Requirement 5). The short deadlines and grounding language make the AD operationally imperative, which in practice invites CASA oversight and follow-up.

• Delegation and signature. The AD is signed by a CASA delegate (James Coyne), which signals the normal administrative backing of CASA for the Directive (signature block and date). That indicates the AD is an official CASA instrument.

What the AD does not specify

• The AD contains no express penalty clauses (for example, no stated fines, suspension or penalties, and no procedure for notice, rectification periods beyond the specified compliance windows, or appeal mechanisms). Practitioners must therefore look to CASA’s broader statutory framework and enforcement instruments for the legal consequences of non-compliance.

• The AD does not describe an audit or inspection regime by CASA or third parties, nor does it describe record-keeping requirements beyond allowing the records check option for Table 2 and the note that a PPL-holder may certify that check (Note 3).

Practical implications for enforcement and compliance

• Because the AD requires "Before further flight" compliance, the practical enforcement lever is operational: an aircraft that has not complied should not be flown. CASA has the statutory capacity to ground aircraft, suspend certificates, or take enforcement action under broader aviation law; although the AD does not narrate those mechanisms, the mandatory nature of the AD plus its immediate compliance times mean that non-compliance is an operational safety matter likely to attract regulatory attention.

• The AD’s lack of internal penalty text places importance on accurate maintenance records and documented compliance. If a Table 2 operator relies on the records-check path under Requirement 2.b, that determination must be recorded and (if done by the operator) certified by someone holding at least a private pilot’s licence. That record will be central to an enforcement inquiry if CASA questions compliance.

• For parts suppliers and maintenance organisations, Requirement 5 creates a compliance gate: installing a P/N 2013142-18 valve on or after the effective date without first performing the prescribed inspection could be evidenced in installation logs and would therefore be a focal point in any enforcement exam.

In sum, the Directive prescribes mandatory inspections and timings but leaves the formal sanctioning mechanism to CASA’s broader regulatory powers; the Directive itself does not set out penalty provisions.

The AD explicitly cross-references the United States FAA Airworthiness Directive FAA AD 2008-10-02 Amdt 39-15508 (noted as becoming effective on 12 May 2008); Note 4 states "FAA AD 2008-10-02 Amdt 39-15508, which becomes effective on 12 May 2008, refers." That cross-reference signals trans-national regulatory coordination: CASA adopted an AD addressing the same defect and referenced the FAA action as related material. The Background explains the issue originated with FAA reports and manufacturer quality control checks and that Cessna corrected parts held in stock (Background; Note 4).

CASA’s AD also diverges in one practical way from the FAA AD by "varying the inspection requirements to allow the aeroplane operator to determine if a P/N 2013142-18 selector valve has been installed since 19 November 2007" (Background). That variation is operationalised in Requirement 2.b and Note 3, which permit a records-based determination for the Table 2 cohort and authorise a PPL-holder operator to certify that maintenance-records check. This demonstrates an interaction where CASA aligned with the FAA's safety concern while introducing a tailored compliance option relying on operator-maintenance record systems and limited operator self-certification.

The AD’s interaction with manufacturer obligations is also stated in the Background: Cessna reported corrections to parts held in stock but could not verify how many assemblies had been shipped with the placard incorrectly fitted, and CASA likewise could not determine which aeroplanes had affected valves without inspection (Background). The AD therefore interacts practically with manufacturer spare-part management and supply chains by imposing a pre-installation inspection duty for P/N 2013142-18 on parts installed on/after the effective date (Requirement 5).

On the domestic administrative law plane, the AD is an instrument of CASA. The AD does not quote the statutory powers under which CASA issues ADs, nor does it cite the Civil Aviation Act or associated regulations within the AD text; those statutory foundations exist outside the AD text but are not repeated here. Practitioners should therefore treat the AD as an operative CASA directive and consult CASA’s enabling legislation or regulatory guidance for enforcement mechanics, appeals or review avenues,those are not contained in the AD itself.

Practical cross-jurisdictional implications

• Operators that fly internationally or exchange parts between jurisdictions should note the cross-reference to the FAA AD. Cessna’s parts and affected serials are international; the AD references the FAA action and records that manufacturer stock was corrected. The AD does not compel operators to undertake actions beyond the stated requirements, but the cross-reference indicates the same technical defect is subject to measures in other jurisdictions.

• The AD’s note that P/N 2013142-18 replaced earlier P/Ns 2013142-9, -13 and -17 (Note 2) is significant for maintenance record searches and parts identification: technicians must check both the part number and any superseding history when applying the records-check option in Requirement 2.b.

Absent provisions and regulatory follow-through

• The AD does not state how CASA will monitor or audit compliance, nor does it provide express enforcement steps or refer to appeal processes. For those subjects, the AD must be read alongside CASA’s statutory enforcement powers and guidance documents, which are not quoted in the AD itself.

• The AD does not alter pilot licensing rules except to allow a PPL-holder operator to certify a records check; it does not relieve maintenance holder responsibilities under the broader maintenance and continuing airworthiness regulatory framework.

The Directive text supplied contains an issuance and effective date but no subsequent amendments within the text provided. The recorded timeline and amendment notes in the source are:

• Issuance/signature: The AD is dated 6 May 2008 and is signed by James Coyne, Delegate of the Civil Aviation Safety Authority (signature block, 6 May 2008).

• Effective date: The AD states "This Airworthiness Directive becomes effective on 13 May 2008." (Compliance).

• Reference to a related FAA AD: Note 4 references FAA AD 2008-10-02 Amdt 39-15508, which "becomes effective on 12 May 2008." The CASA AD therefore aligns temporally with the FAA AD and became effective one day later (Note 4; Compliance).

• Variation from FAA: The Background states that CASA "has varied the inspection requirements to allow the aeroplane operator to determine if a P/N 2013142-18 selector valve has been installed since 19 November 2007." That operational variation is embodied in the requirements (Background).

• No later amendments or revocations are included in the supplied text. The AD includes no textual history of prior versions or later revisions, nor does it list Ministerial or legislative amendments. The document as presented appears to be a single issuance AD with a fixed effective date and the specified requirements.

Practitioner implications of the stated history

• The AD’s single-issue nature and close coordination with FAA timing suggests it was a reactive directive issued in response to a specific manufacturing/quality control discovery at Cessna (Background). The AD text includes the essential dates necessary for compliance (effective date 13 May 2008 and the 19 November 2007 cut-off used in the records-check option).

• Because there is no amendment log in the supplied text, anyone needing the current legal status or any superseding directives must check CASA’s AD registry or the relevant aeronautical information publications for updates or recissions beyond the supplied document.

• The AD’s reference to a window of manufacture for affected placards (manufactured between 20 November 2007 and 18 February 2008) is included in the Background; that window assists in tracing affected parts, but the AD does not amend that window after issuance in the text provided.

If a practitioner needs to know whether any later amendments, supersessions or revocations occurred after this AD, they must consult CASA’s AD database or subsequent CASA publications, because the supplied document contains no further amendment history.

The supplied Airworthiness Directive does not include or reference any litigation history. The AD text contains background statements, applicability tables, requirements and notes, but no record of legal challenges, judicial review or tribunal proceedings relating to the AD itself. Specific points to note:

• No court cases or decisions are quoted or cited in the AD. The Background describes technical findings and manufacturer stock correction, but there is no mention of disputes, hearings, or litigation.

• The AD is presented as an administrative safety measure issued by CASA and signed by a delegate; the text does not include any reference to legal challenges or procedural objections raised by stakeholders.

• Practitioners seeking to know whether this AD was the subject of appeals, reviews, or enforcement proceedings should consult court records, regulatory enforcement registers, or CASA publications external to the AD. The AD text itself contains no litigation history.

Where litigation history would matter

• If an operator were to rely on a records-check to avoid physical inspection (per Requirement 2.b and Note 3), and CASA later took enforcement action, litigation history or precedent concerning CASA’s enforcement of ADs could inform strategy. The AD itself does not supply that history, so practitioners must look to broader CASA case material or judicial decisions about enforcement of ADs under the Civil Aviation Act and related regulations.

• Absence of litigation history in the AD does not imply absence of later disputes; it simply means none are recorded within this instrument.

The AD contains several practical and legal pitfalls that operators, maintenance organisations and compliance officers should treat as high priority. These are concrete, directive-derived issues that practitioners must watch for.

1. Immediate grounding risk. The compliance timing for Requirements 1, 2 and 3 is "Before further flight after the effective date of this Directive" (Compliance). That language means that affected aeroplanes that have not yet completed the required inspection or records-check are not to be flown beyond the effective date without compliance. Failure to appreciate that the AD imposes an immediate operational halt until compliance is achieved is a material operational risk.

2. Distinction between Table 1 and Table 2. Table 1 aircraft "had the affected part installed at manufacture" and therefore must undergo the physical inspection in Requirement 1. Table 2 aircraft "could have had the affected part installed as a replacement part or from parts held as spares" and are granted a records-check alternative (Table 1; Table 2; Requirement 2). Misclassifying an aircraft between the tables could lead to an incorrect compliance path and potential non-compliance.

3. Records-check is limited and certifiable only by certain persons. Note 3 permits the aeroplane operator, provided they hold at least a private pilot’s licence, to accomplish and certify the Requirement 2.b records inspection. The AD does not extend this authority to persons without at least a private pilot’s licence. Operators must ensure the person undertaking and certifying the records-check meets this threshold. The AD does not describe the required form of certification or the record entry language, so maintainers must adopt best practice documentation to evidence the operator’s determination.

4. Physical inspection technique matters. Requirement 1 prescribes concrete steps: "Adjust the pilot and copilot seats as far aft as possible" (Requirement 1.a) and "Use a flashlight and mirror to inspect the alternate static air source selector valve to assure the port on the forward end of the valve is clearly visible and not covered by the part number identification placard" (Requirement 1.b). The AD therefore anticipates limited access that requires seat movement and inspection aids. Failure to follow the prescribed technique could produce false negatives (declaring a port unobstructed when it is not) or false positives.

5. Discarding the placard. If the placard obstructs the port the AD requires removal and discarding of the placard (Requirement 4). That is a non-reversible physical alteration to the valve assembly and spare parts record; operators should document the removal and consider traceability implications for maintenance records and future part identification.

6. Pre-installation inspection obligation for parts installed on/after the effective date. Requirement 5 requires inspection before installation of any P/N 2013142-18 valve fitted as a modification or replacement part on or after the AD’s effective date. That duty places an upstream compliance step in installation workflows: technicians, parts managers and shops must check the part prior to fitting. Failure to do so could result in installing an uninspected part and non-compliance.

7. Part-number supersession and identification. Note 2 states "P/N 2013142-18 replaced P/Ns 2013142-9, -13 and -17." Practically this means that searching maintenance records for P/N history requires examination of superseded numbers. If a records-check only looks for earlier P/Ns or misunderstands supersession, the operator may erroneously conclude no P/N 2013142-18 was installed.

8. Manufacturer stock uncertainty. The Background records that Cessna corrected parts held in stock but "has no way of verifying how many of these assemblies were manufactured and sent to the field" and 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." That creates a latent information risk: even if an operator has not recorded a replacement, the aircraft might still contain an affected valve installed at manufacture or via an undocumented parts swap. The records-check path is permissible for Table 2 only if it establishes the absence of P/N 2013142-18 since 19 November 2007; inconsistent or incomplete records may not be relied on.

9. Instrumentation effect severity. The Background warns the condition "could result in the altimeter, airspeed and vertical speed indicators displaying erroneous indications" and "possibly result in loss of control." This is a high-consequence risk which explains the AD’s immediate timings. Practitioners must treat the technical risk as serious and ensure the inspection is completed properly and documented.

10. No specific penalty or recording format in the AD. The AD does not set out penalties nor specify the precise logbook entries or certification wording required. That leaves operators to rely on standard maintenance recording practice to evidence compliance. In a compliance audit or enforcement action, poor documentation could make it difficult to prove compliance, even if the physical inspection occurred.

11. Multiple affected series and "All S/Ns" entries. Table 2 contains many entries noted as "All S/Ns", which captures entire fleets of certain submodels. Operators must carefully map registration/serial numbers to the Table entries to determine applicability. Misreading the Table could lead to incorrect compliance handling.

12. Timing overlap with FAA AD. The AD references FAA AD effective 12 May 2008 whereas CASA’s AD becomes effective 13 May 2008. Practitioners operating internationally should note the near-simultaneous timing but also CASA’s variation in inspection approach for some aircraft. Cross-border operators should align with the most restrictive applicable requirement in their operating jurisdiction.

This section translates the AD’s requirements into concrete compliance steps, record-keeping practices and organisational checkpoints. Follow the AD’s own numbered requirements as the controlling source.

1. Establish applicability for your aeroplane(s).

• Locate the aircraft model and serial number and compare against Table 1 and Table 2 in the AD. Table 1 lists aircraft that "had the affected part installed at manufacture" and thus require the physical inspection of the valve (Table 1). Table 2 lists models and either specific serial number ranges or "All S/Ns" entries; these aircraft "could have had the affected part installed as a replacement part or from parts held as spares" and permit the records-check alternative (Table 2). Do not assume applicability; verify against the precise Table entries.

2. For Table 1 aircraft: perform Requirement 1 inspection prior to further flight.

• Adjust the pilot and copilot seats as far aft as possible (Requirement 1.a). This is a mandatory procedural step before attempting to access and view the forward port.

• Use a flashlight and mirror to inspect the alternate static air source selector valve to assure that the port on the forward end of the valve is clearly visible and not covered by the part number identification placard (Requirement 1.b). Follow iterative checks to ensure the inspection is thorough; use a second person if needed for lighting or to manipulate controls while observing.

• If the port is found obstructed by the part number identification placard, remove the placard from the valve body and discard it, and assure the port is open and unobstructed (Requirement 4). After placard removal, re-check the port to confirm unobstructed flow path.

• Record the inspection and any rectification in the aircraft maintenance log and, where applicable, the component history card or scheduled maintenance records. Although the AD does not prescribe a particular log entry format, contemporaneous entries should include: AD reference (AD/CESSNA 170/83), date and time of inspection, person performing the inspection, result (port obstructed / not obstructed), action taken (placard removed / no action required), and signature and licence or certificate held by the inspector. Retain photographic evidence where practicable to demonstrate the port’s condition before and after placard removal.

3. For Table 2 aircraft: choose the permitted compliance path and execute it before further flight.

• Option A (physical inspection): perform the same Requirement 1 physical inspection steps as described above (Requirement 2.a). If the port is obstructed, remove and discard the placard as per Requirement 4.

• Option B (records check): inspect the aircraft’s maintenance records to determine whether the alternate static air source selector valve has been replaced since 19 November 2007 with P/N 2013142-18 (Requirement 2.b). If the records show no replacement with P/N 2013142-18 since 19 November 2007, no further action is necessary under the AD for that aircraft. If the records show that a P/N 2013142-18 was installed since 19 November 2007, then the operator must perform the Requirement 1 physical inspection on the valve (Requirement 3).

• Note 3 allows the aeroplane operator to accomplish and certify the Requirement 2.b records inspection if the operator holds at least a private pilot’s licence. Ensure the certifying person holds the requisite licence and that the certification is documented in the maintenance records. Documentation should include the certifier’s name, licence number, date of the records inspection, the records examined, the conclusion (no P/N 2013142-18 installed since 19 November 2007 / P/N 2013142-18 installed), and their signature.

4. If a placard is removed, document and manage the component traceability.

• Requirement 4 mandates removal and discarding of the placard when it obstructs the port. Removing an identification placard affects traceability for the component and spare-part inventory. Make a maintenance entry noting the placard removal, the reason (AD/CESSNA 170/83 Requirement 4), date and person. If the part needs to be traced later, document the valve’s serial number and any other identifying marks before discarding the placard.

• Where organisational procedures require, affix an alternative, non-obstructive identification marking or record the part serial/P/N in the component records so future maintainers can identify the part without placing a placard over the port.

5. For installation of new or replacement P/N 2013142-18 valves post-effective date: inspect prior to installation.

• Requirement 5 requires inspection of P/N 2013142-18 valves installed as modification or replacement parts on or after the AD effective date, and the inspection must be performed in accordance with Requirement 1 prior to installation. That means before fitting a P/N 2013142-18 valve to any aeroplane, the installer must visually confirm that the forward port is unobstructed by the part number identification placard using the same seat adjustment and flashlight/mirror technique required for installed valves.

• Document the pre-installation inspection in parts logs, installation records and the aircraft maintenance log entry for the installation event, referencing AD/CESSNA 170/83 Requirement 5.

6. Retain evidence and plan for follow-up.

• Because the AD provides immediate "Before further flight" timings, plan inspections to avoid unnecessary operational downtime. Where feasible, coordinate inspections with scheduled maintenance or downtime. Ensure spare parts held in stock are inspected before installation and that stock records are updated to reflect inspected condition.

• Maintain photos where possible to show the port condition before and after any placard removal, and keep copies of maintenance-records checks completed under Requirement 2.b. If an operator relies on the records-check path and is later audited, robust documentation of the records inspected and the certifying PPL-holder will be decisive.

7. Verify part numbers and supersessions.

• Note 2 states P/N 2013142-18 replaced P/Ns 2013142-9, -13 and -17. When searching records under Requirement 2.b, examine records for the listed P/Ns and any supplier change history or part supersession notes to ensure no P/N 2013142-18 was installed under a different or superseded identifier.

8. Coordinate with parts suppliers and maintenance organisations.

• Notify parts suppliers and maintenance shops that P/N 2013142-18 valves must be inspected prior to installation if they are to be fitted on or after the effective date (Requirement 5). Where organisations hold stock of P/N 2013142-18 or the replaced P/Ns, they should inspect inventory and update stock records.

9. Consider safety and operational implications.

• The Background warns the defect could yield erroneous altimeter, airspeed and vertical speed indications and possibly loss of control. Treat the inspection as safety-critical and ensure the person doing the inspection is competent to identify the obstruction and perform the required remedial action. While Note 3 permits a PPL-holder to certify a records-check, physical inspections and placard removals are maintenance actions that should be performed by appropriately qualified maintenance personnel unless local rules and organisational approvals permit otherwise.

10. If in doubt, escalate to CASA guidance or maintenance authority.

• The AD text does not provide enforcement procedures, log-entry wording or appeals processes. Organisations uncertain about the interpretation of the AD, the required personnel qualifications to execute Requirement 1 physical inspections, or the necessary logbook statements should seek guidance from CASA or their nominated maintenance authority. Also confirm whether any subsequent CASA ADs or manufacturer service bulletins provide further detail or amendments.

By following the AD’s numbered Requirements, documenting each step carefully and coordinating with parts suppliers and maintenance organisations, operators can meet the AD’s immediate safety-improvement objectives and create an audit trail sufficient to demonstrate compliance in the absence of AD-specific penalty language within the Directive text.