AD/G2T1/1 - Induction System Inspection

The Directive is organised around a small set of technical concepts and compliance mechanics drawn directly from the AD text.

Applicability. The AD is limited to Great Lakes Aircraft Company Model 2T-1A-1 and 2T-1A-2 aeroplanes fitted with a Lycoming IO-360-B1F6, AIO-360-B1G6 or AEIO-360-B1G6 engine. The applicability is explicit: if the engine models listed are not installed, the AD does not, on its face, apply (the AD’s applicability box lists those engine models).

Inspections and corrective hierarchy. The AD sets a sequence of inspections followed by conditional corrective actions:

• Inspect the induction elbow drain fitting for blockage (Requirement 1). If blocked or restricted (weld area or not drilled through), remediate by creating/opening a No.10 (0.193 inch) hole at the fitting location (Requirement 2).
• Inspect the alternate air door for distortion, heat damage and cracks (Requirement 3). If any damage is found, repair or fabricate a new door in accordance with the three figures included in the Directive (Requirement 4).
• Inspect the induction system for air-filter cleanliness, distortion, security, and damage from backfire or induction-system fire (Requirement 5). If problems are found, repair, replace or modify affected components (Requirement 6).

Time in Service (TIS) and compliance timing. The AD uses the aviation maintenance metric “time in service (TIS)”, defined in the table as the compliance clock for inspections and intervals. Requirements 1, 3 and 5 must be done within 25 hours TIS after the effective date; Requirements 3 and 5 must then be repeated at intervals not to exceed 100 hours TIS. Requirements 2, 4 and 6 are “before further flight” actions, i.e. they must be completed prior to the next flight if the corresponding inspection reveals defects.

Technical specification for corrective action. The AD prescribes a specific drill size where a hole must be drilled: No.10 (0.193 inch). For the alternate air door, the AD requires repair or fabrication “in accordance with Figure 1, Figure 2 and Figure 3 in this Directive.” The Directive therefore combines a prescriptive numeric specification (drill size) with a reference to illustrative/design figures for door fabrication and repair.

Relationship to FAA AD. The text includes a note that FAA AD 2004-25-22 Amendment 39-13910 refers. The AD therefore signals that the CASA directive tracks or incorporates by reference issues identified by the FAA in that amendment. The Directive’s background also explicitly states it was issued “following advice from the FAA” about reports of induction system damage on the specified engines.

Stated safety objective. The AD includes a background statement that the specified actions are “intended to prevent the aircraft induction system from becoming blocked or restricted, which could result in engine failure. This failure could lead to loss of control of the aeroplane.” That statement identifies the risk the AD is addressing: blockage/restriction of the induction airflow, and consequent engine performance loss.

Administrative details. The AD identifies itself by code AD/G2T1/1, carries the date 2/2005, and the date of signing 6 January 2005, with an effective date of 17 February 2005. The Directive is signed by a delegate of the Civil Aviation Safety Authority.

Owners and operators. The Directive applies to the owners and operators of Great Lakes Model 2T-1A-1 and 2T-1A-2 aircraft that have one of the listed Lycoming engines installed: IO-360-B1F6, AIO-360-B1G6 or AEIO-360-B1G6. The applicability language in the AD is explicit and limits the covered population to those model/engine combinations.

Maintenance organisations and mechanics. Licensed maintenance personnel or maintenance organisations that perform the inspections and carry out the corrective actions are materially affected. The AD requires visual inspections and, in some cases, repair, fabrication or drilling a No.10 (0.193 inch) hole in the induction elbow. Those tasks will typically fall to appropriately authorised aircraft maintenance technicians. The AD does not specify who is authorised to perform the work, nor does it prescribe certification levels in the text; it prescribes the physical acts to be completed.

Regulators and inspectors. The Civil Aviation Safety Authority is the issuing authority; the AD is signed by a CASA delegate (David Punshon). CASA, or its delegated representatives, are stakeholders for implementation and monitoring. The AD makes reference to FAA material, so foreign regulators and those responsible for maintaining conformity with international guidance may need to consider the FAA AD referenced.

Pilots and operators scheduling flights. The compliance structure includes "before further flight" requirements (Requirements 2, 4 and 6). Where an inspection uncovers a defect requiring a “before further flight” remedy, operators must ground the aeroplane until the corrective work is completed. That affects flight planning and potential revenue or availability for those who operate the aircraft commercially or privately.

Costs fall primarily on owners/operators. The AD prescribes inspection intervals and remedial work that will require labour and, in some cases, parts or fabrication of new alternate air doors. Costs are therefore borne by the aircraft owner/operator or the maintenance organisation contracted by them. The AD itself does not allocate funding or compensation. The directive also imposes operational costs: aircraft downtime for inspections, possible grounding while corrective work is carried out, and recurrent inspections (Requirements 3 and 5 at intervals not exceeding 100 hours TIS).

Parts suppliers and fabricators. Requirement 4 directs repair or fabrication of a new alternate air door “in accordance with Figure 1, Figure 2 and Figure 3 in this Directive.” Where repair requires fabrication, that work may involve parts suppliers or fabricators to replicate or produce parts consistent with the figures provided.

Limitations and scope. The Directive’s scope is narrow and engine-specific. Aircraft owners/operators whose aeroplanes do not have the specified Lycoming engines are not within the AD’s stated applicability and therefore not subject to these mandatory inspections under this AD as it is written.

Duties established by the Directive. The AD sets out specific duties for operators/maintainers of affected aircraft:

• Inspect the induction system drain fitting in the induction elbow below the fuel injector for blockage/restriction (Requirement 1). This inspection must be completed within 25 hours TIS after the AD’s effective date.
• If blockage/restriction is found as described, open the restricted hole or drill a No.10 (0.193 inch) hole at the fitting location (Requirement 2). This corrective action must be completed before further flight after the inspection.
• Inspect the alternate air door for distortion, heat damage and cracks (Requirement 3), to be done within 25 hours TIS after the effective date and thereafter at intervals not to exceed 100 hours TIS.
• Repair or fabricate a new alternate air door where damage is found, and do so “in accordance with Figure 1, Figure 2 and Figure 3 in this Directive” (Requirement 4). The repair or fabrication must be completed before further flight following the inspection.
• Inspect the induction system for cleanliness of the air filter, for distortion, for security, and for damage from backfire or induction system fire (Requirement 5). This inspection is within 25 hours TIS after the effective date and then at intervals not to exceed 100 hours TIS.
• Repair, replace or modify all affected components where the air filter is dirty or any distortion, damage or lack of security is found (Requirement 6). This corrective action must be done before further flight.

Timing obligations and operational consequence. The AD draws a clear line between scheduled inspections (within 25 hours TIS, and recurring inspections at 100-hour intervals) and immediate grounding until corrective actions are completed (before further flight). Therefore, if an inspection reveals a defect that triggers Requirements 2, 4 or 6, the aircraft must remain on the ground until repaired in accordance with the AD.

Specific technical duty. The Directive prescribes an explicit drill size for use if the induction elbow hole is not drilled or is restricted: No.10 (0.193 inch). That numeric prescription is a mandatory technical specification in the AD text.

Reference to figures for repair/fabrication. For alternate air door defects, the AD requires repair or fabrication “in accordance with Figure 1, Figure 2 and Figure 3 in this Directive.” Those figures form part of the mandatory instructions for the design or repair of that component.

No explicit rights or exemptions set out. The AD text does not set out rights of appeal, exemptions, or alternative means of compliance (AMOC) within the table presented. It also does not include express waiver or deviation processes in the text supplied. The only cross-reference is to the FAA AD. The absence of explicit procedural rights in the AD text means any rights to seek an alternative compliance approach or relief would need to be pursued under the broader regulatory regime or administrative mechanisms that are not described in this Directive text.

Effective date. The AD becomes effective on 17 February 2005; compliance windows are measured from that effective date. The AD is signed by a CASA delegate dated 6 January 2005.

Documented purpose. The Directive explicitly states its intended safety purpose: to prevent induction system blockage or restriction that could lead to engine failure and possible loss of control. That stated purpose underpins the duties set out in the AD.

Textual absence of penalties. The Directive text does not specify penalties, fines, or a sanctions regime for non-compliance. The AD itself, as provided, states the inspections, corrective actions and compliance timings, but contains no express enforcement provisions or penalty clauses within the document content.

Issuing authority. The Directive is issued by the Civil Aviation Safety Authority and is signed by a delegate (David Punshon). The document header and signature identify CASA as the issuing authority, and the AD is presented as an official CASA Airworthiness Directive. That establishes the administrative provenance and formal status of the instruction, but the text does not contain enforcement measures.

Operationally relevant enforcement implication. Because the AD prescribes actions that are tied to airworthiness (inspections and corrective work to prevent engine failure), an operator who does not perform the required inspections and corrective work will, on the face of the AD, remain out of compliance with the directive. The AD does not state the consequences of such non-compliance within the document itself; it does not, in the supplied text, describe processes for enforcement action, grounding orders, licence implications, or civil penalties.

No on-face specification of monitoring or audit mechanisms. The AD does not describe how CASA will monitor compliance, audit maintenance records, or validate that inspections and corrective actions have been completed. The Directive also does not state whether operators are required to submit compliance reports or prove completion to CASA.

Reference to FAA AD. The AD notes that FAA AD 2004-25-22 Amdt 39-13910 refers. The presence of the FAA AD reference may be relevant in enforcement or compliance assessment contexts, but the Directive itself does not specify how CASA will treat or use that FAA AD for enforcement purposes.

Practical consequence for airworthiness status. The AD links its actions to prevention of engine failure and loss of control; while the AD does not spell out enforcement steps, the prescriptive nature of the requirements and the “before further flight” mandates create clear operational constraints. If an operator fails to perform an inspection or to carry out required before-flight repairs after finding defects, that operator would be in breach of the AD’s prescriptive instructions, even though the Directive text does not list the specific legal penalties for such breach.

Reference to FAA material. The sole explicit cross-reference in the Directive is to FAA AD 2004-25-22 Amendment 39-13910, which the AD notes "refers." The background also states the Directive was issued following advice from the FAA regarding reports of damage. The functional interaction identified in the AD text is that CASA’s AD aligns with or follows FAA findings and remedial measures as documented in that FAA AD. The AD does not quote or reproduce the FAA AD text; it only notes the reference.

No other statutory cross-references in the text. The supplied Directive does not cite or reference any Commonwealth aviation statutes, regulations, or civil aviation instruments beyond its own identification as a CASA Airworthiness Directive. It therefore does not, in the text provided, describe how it amends or interacts with other Australian regulatory instruments.

No mention of certification, approvals, or alternative means of compliance. The Directive does not set out how operators could obtain an alternative means of compliance, an exemption, or an approval for a different repair method. It also does not reference maintenance manual requirements or other certification instruments (for example, type certificates, maintenance programme approvals or continuing airworthiness manuals) in the text supplied.

Interplay with maintenance practice. By prescribing technical actions (inspections, a specific drill size, repair or fabrication "in accordance with" provided figures), the AD will affect maintenance programmes and scheduled tasks for affected aircraft. The AD mandates inspection intervals for the alternate air door and induction-system checks; operators will need to incorporate those intervals into their maintenance schedules. The AD text does not, however, specify whether these intervals supersede or augment existing maintenance programme intervals; that relationship is not described in the Directive.

No explicit civil or criminal law interaction described. The AD does not refer to or invoke any civil penalty, licence suspension, criminal sanction or specific enforcement process. How any non-compliance would interact with broader regulatory enforcement powers or aviation safety legislation is not stated in the document supplied.

Jurisdictional note. The AD is a CASA instrument; its applicability and enforcement implications will be within CASA’s jurisdiction as the issuing authority. The AD’s referencing of a FAA AD indicates transnational coordination on a technical safety issue, but the Directive itself does not set out a mechanism for relying on FAA enforcement measures or for harmonising any penalties or administrative actions between jurisdictions.

Identifiers and dates. The Directive is identified as AD/G2T1/1 and dated 2/2005 in the header. The body of the Directive includes the statement "This Airworthiness Directive becomes effective on 17 February 2005." The document bears a signature block attributable to a CASA delegate, David Punshon, dated 6 January 2005.

No prior amendments shown. The text supplied does not include earlier versions, amendment notes, superseded AD identifiers, or a revision history. The AD header shows "2/2005" which appears to be the issue code or serial date label for this Directive. There is no in-document chronology of prior iterations or subsequent amendments.

Reference to FAA amendment. The AD includes a note that refers to "FAA AD 2004-25-22 Amdt 39-13910." That Federal Aviation Administration amendment is the only external regulatory instrument identified in the Directive, and it forms part of the factual background that led to CASA issuing this AD. The AD text does not state that it amends or replaces any previous CASA AD.

No sunset, review or revision timetable in the text. The Directive sets inspection intervals (25 hours initial window and 100-hour recurring intervals for some inspections) but does not contain an expressed provision for review, scheduled amendment, or revocation. The text supplied does not indicate whether CASA intended a future review or how the AD might be rescinded once affected aircraft had reached compliance or once engineering changes had been made.

No record of consolidation in this document. There is no consolidation note, erratum or annex indicating updates to figures or technical detail. The AD, as supplied, includes Figures 1-3 which are referenced for fabrication/repair of the alternate air door. There is no record in the supplied text of those Figures being amended, replaced, or superseded.

Summary. The supplied AD shows a single issuance with signing on 6 January 2005 and an effective date of 17 February 2005, and it references an FAA AD as background. The Directive text contains no internal amendment history or later modification records.

No litigation referenced or included. The Directive text provides no indication of any litigation having been brought in relation to this AD, nor does it contain references to judicial decisions, administrative appeals or dispute resolution proceedings arising from the AD.

No cases named. The AD does not cite case law, decisions or precedents. The only external document referenced is FAA AD 2004-25-22 Amendment 39-13910; that is an administrative instrument rather than a judicial decision.

No record of challenges or legal commentary in the text. The AD contains only the prescriptive requirements, compliance times, and the background statement. It does not describe any history of legal challenge, petition for relief, or any administrative appeal process connected to this particular AD.

Implication for legal practitioners. The absence of litigation material in the AD means there is no source-provided judicial interpretation to guide disputes about the AD’s meaning, scope, or enforceability in the supplied text. Any legal challenge, interpretation dispute, or appeal related to the AD would need to be identified from other sources outside the Directive document itself.

Narrow applicability may cause missed scope. The AD applies only to Great Lakes Model 2T-1A-1 and 2T-1A-2 aeroplanes fitted with the three specified Lycoming engines. Aircraft owners or maintenance managers must check engine type before assuming applicability. If engine type is incorrectly assumed or not verified, the wrong compliance posture could result.

Immediate grounding when defects are found. Requirements 2, 4 and 6 are mandatory corrective actions that must be completed "before further flight" if the antecedent inspection finds defects. Practically, that means an aeroplane discovered to have a blocked induction elbow drain fitting, a damaged alternate air door, or an unclean/unsafe air filter must not be flown until repair, drilling, replacement or fabrication is complete. Operators should anticipate potential grounding and schedule inspections at times that minimise disruption.

Subjective inspection criteria. Several inspection mandates use terms that are descriptive and potentially subjective: "cleanliness of the air filter", "distortion", "security", "damage from backfire or induction system fire", and "heat damage and cracks" for the alternate air door. The AD does not provide quantitative thresholds for these descriptors; maintenance personnel will need to exercise judgement about what constitutes a reportable defect, guided by accepted maintenance standards and the AD’s safety intent.

Prescriptive drilling size. Requirement 2 specifies a No.10 (0.193 inch) drill if the induction elbow hole is not drilled through or is restricted in the weld area. That prescriptive technical specification leaves little room for deviation: if the hole is restricted or not drilled through, the AD directs the use of that drill size. There is no alternative size or acceptance criteria provided in the AD text.

Figures are mandatory but not described in text. Requirement 4 requires repair or fabrication "in accordance with Figure 1, Figure 2 and Figure 3 in this Directive." The AD therefore depends on the details contained in those figures. If a recipient of the AD does not have access to or cannot interpret the figures, they will lack the detailed dimensional/design instructions the AD makes mandatory. The figures are integral to compliance for alternate air door repair/fabrication.

Timing windows and recurring inspections. Requirements 1, 3 and 5 must be performed within 25 hours TIS after the effective date, with Requirements 3 and 5 recurring at intervals not to exceed 100 hours TIS. Operators that miss the initial 25-hour window will face questions about retrospective compliance; the AD does not specify remedial steps if the initial inspection window is missed.

No specified means of alternative compliance or deviation. The AD text does not provide an explicit mechanism for an alternative means of compliance (AMOC) or for seeking approval of different repair methods. Where an operator or designer believes an alternative fix is appropriate, the AD does not describe the procedural path to obtain CASA approval within the document itself.

No penalties or enforcement detail stated. The AD does not set out penalties, reporting obligations, or enforcement processes, so recipients cannot rely on the text of this Directive alone to understand enforcement risk or administrative steps following non-compliance.

Dependency on FAA material. The AD refers to FAA AD 2004-25-22 Amdt 39-13910. The CASA Directive is brief and relies partially on the FAA’s earlier work for background. Absent examination of the FAA AD, an operator may miss related instructions, broader background, or alternative details that could affect implementation.

Potential for misinterpretation of "security". The AD requires inspection for "security" of the induction system. That term could refer to fastenings, clamps, or attachment points; the AD does not define it. Maintenance personnel should ensure inspection covers mechanical fastening and retention systems for induction components.

Scope limitation to specific engines only. The AD is tightly engine-specific. If aircraft have engine variants that are similar but not the three model numbers listed, the AD text does not apply. That creates a compliance decision point for aircraft with non-listed engines but similar induction hardware: the AD does not mandate inspection for them.

Documentation not mandated in the AD text. The Directive itself does not set out a recordkeeping requirement or require reporting of compliance. Absent a compliance-report requirement in the AD, operators still face operational and safety incentives to document inspections and corrective actions, but that documentation obligation is not contained in the Directive text itself.

Follow the AD’s sequence and timing precisely. The AD sets out discrete inspections and conditional corrective actions with defined compliance windows. The basic compliance steps are:

1. Verify applicability. Confirm the aeroplane is a Great Lakes Model 2T-1A-1 or 2T-1A-2 and that it is fitted with a Lycoming IO-360-B1F6, AIO-360-B1G6 or AEIO-360-B1G6 engine. The AD’s applicability box is explicit about the covered engine models.

2. Requirement 1 , Induction elbow drain fitting inspection. Within 25 hours TIS after the AD effective date, visually inspect the induction system drain fitting located in the induction elbow below the fuel injector for any blockage or restriction. If no restriction is found, no immediate corrective action under Requirement 2 is necessary.

3. Requirement 2 , Remedial drilling if required. If Requirement 1 finds the hole blocked or restricted in the weld area or not drilled through the elbow, open the restricted hole or drill a No.10 (0.193 inch) hole in the elbow at the fitting location. This corrective action must be completed before further flight after the inspection that revealed the condition.

4. Requirement 3 , Alternate air door inspection. Within 25 hours TIS after the AD’s effective date, visually inspect the alternate air door for distortion, heat damage and cracks. Thereafter, repeat this inspection at intervals not to exceed 100 hours TIS.

5. Requirement 4 , Alternate air door repair/fabrication. If the Requirement 3 inspection identifies any distortion, heat damage or cracks, repair or fabricate a new alternate air door in accordance with Figure 1, Figure 2 and Figure 3 included in the Directive. The repair or fabrication must be completed before further flight following the inspection.

6. Requirement 5 , Induction system inspection for filter and damage. Within 25 hours TIS after the AD’s effective date, inspect the induction system for cleanliness of the air filter, for distortion, security and damage from backfire or induction system fire. Repeat this inspection at intervals not to exceed 100 hours TIS thereafter.

7. Requirement 6 , Repair/replace/modify components found defective. If Requirement 5 identifies a dirty air filter, distortion, damage or lack of security, repair, replace or modify all affected components before further flight.

Use the specified technical parameters. Where the AD prescribes a measurement (No.10 drill, 0.193 inch), use that specification. For alternate air door fabrication or repair, follow Figures 1-3 as the AD prescribes.

Plan for grounding risk and maintenance scheduling. Because several corrective actions must be completed before further flight when defects are found, schedule initial inspections at a time that will allow for the possibility of repairs or parts replacement without unduly disrupting operations. Allocate labour, tooling (for drilling), and access to fabrication resources for the alternate air door if required.

Ensure competent maintenance personnel perform work. The AD requires visual inspections, drilling and possible fabrication. Assign these tasks to appropriately qualified and authorised maintenance personnel consistent with the operator’s regulatory and organisational maintenance approvals. The AD does not describe qualification levels; organisations must deploy personnel authorised under their own regulatory frameworks.

Obtain and use the Figures. Requirement 4 explicitly requires repair or fabrication “in accordance with Figure 1, Figure 2 and Figure 3 in this Directive.” Ensure the maintenance team has a clear copy of those Figures and applies them precisely when repairing or fabricating an alternate air door.

Document completed inspections and corrective actions. The AD itself does not impose a recordkeeping requirement in the supplied text, but operators should (as a practical matter) record the date, time in service at inspection, findings, corrective actions taken (including drill size used and fabrication references), and the person or organisation who performed the work. Such documentation will be the primary evidence that the AD’s requirements have been satisfied, should any administrative query arise.

Coordinate with the FAA AD where relevant. The AD notes FAA AD 2004-25-22 Amdt 39-13910 refers. Review that FAA AD for any technical detail, background, or advice that may bear on repair methods, especially if the FAA AD contains supplemental details not reproduced in the CASA AD.

Incorporate recurring inspections into maintenance scheduling. Requirements 3 and 5 require repeat inspections at intervals not to exceed 100 hours TIS following the initial 25-hour inspection. Update the aircraft’s maintenance schedule or inspection plan to include those recurring checks to maintain ongoing compliance with the AD’s interval requirements.

Treat “before further flight” conditions as grounding events. If an inspection reveals the conditions that trigger a before-flight corrective action, do not operate the aircraft until the specified remedial work is done.

If in doubt, seek clarification from CASA. The AD text does not describe a process for alternative methods of compliance or waivers. If an operator believes a different repair method or timing is necessary, or if Figures 1-3 are ambiguous, seek formal guidance or instruction from CASA or other authorised regulatory representatives rather than deviating from the AD’s prescriptive requirements.

Retain parts and evidence where appropriate. Where repairs involve component replacement or fabrication, retain removed parts, materials specifications, and fabrication drawings (including references to the AD Figures) until the maintenance record is closed. This supports transparency and traceability of the corrective action adopted to meet the AD’s instructions.

Summary of minimum actions. The minimum compliance route is: confirm applicability, perform the three initial inspections within 25 hours TIS, perform any required before-flight corrective actions immediately, and thereafter perform the alternate air door and induction-system inspections at intervals not to exceed 100 hours TIS, with repairs or replacements implemented when defects are found.