AD/SWSA226/47 Amdt 3 - Hydraulic, Electrical and Oxygen System

Core concepts are inspection, modification, containment, and clearance management. The Directive distinguishes between repetitive inspections (Para 1 and Para 6), one-off hardware changes (Para 2 insulator and spiral wrap; Para 3 fluid purge and placard change), and system modifications (Paras 4 and 5) which may remove the need for recurring inspections for certain aircraft. The Directive deploys manufacturer service documents as normative references: Fairchild Service Bulletins SB No 24-021, SB24-03, SB No. 226-29-005, SB No. 226-35-003, and Service Notes 226-SN-145 and 227-SN-052, and it instructs conformity with the Fairchild Maintenance Manual for specified procedures (Para 1 H).

Clearances are specified quantitatively in the text. Oxygen lines must maintain a minimum 2-inch clearance from moving parts, and there is a desirable 6-inch clearance between oxygen tubing and electrical wires; if 6 inches is not achievable, electrical wires must be fastened so they are not closer than 2 inches to oxygen tubing (Para 1 H, L). The text specifies particular inspection methods, for example use of MIL-L-2556713 leak detector solution or equivalent as specified in the Fairchild Maintenance Manual to detect oxygen leaks (Para 1 H). Hydraulic fluid types are treated as safety-relevant: where MIL-H-5606 was used, aircraft in specified serial-number ranges must have the main hydraulic fluid drained and purged and placards changed to specify MIL-H-83282 (Para 3). The Directive also instructs inspection of hydraulic system pressure gauge and tubing with the system pressurised, and brake master cylinder flexible hoses with brakes pressurised (Para 1 C, E, F).

Compliance is time-bound. Initial inspections must be carried out within 65 hours time in service after 31 May 1984 unless already done in accordance with the original AD (Para 1 Compliance). Subsequent intervals for the repetitive inspections are not to exceed 260 hours time in service. Some requirements must be completed before further flight after specific dates (Paras 4 and 5 before further flight after 31 December 1985). The Directive also identifies a conditional relief path: aircraft modified per Paras 4 and 5 and equipped with anti-skid brake systems are exempt from Para 1 repetitive inspections; if modified per Paras 4 and 5 but not equipped with anti-skid, only inspection D (front pressure bulkhead area brake reservoir vent area) of Para 1 applies (Compliance).

Finally, cross-jurisdictional reference exists: the AD notes FAA ADs 83-19-02, 84-05-01 and 85-04-01 as referring matters, indicating overlapping regulatory actions elsewhere, while explicitly updating its own requirement documents and applicability (Note, Background).

The Directive applies to all model SA226T, SA226-T (B) and SA226-AT and SA226-TC, and all model SA227-AT, SA227-TT and SA227-AC aircraft, with additional serial-number-specific obligations in Paras 3 to 6 (Applicability and Paras 3-6). Owners, operators, maintenance organisations and licensed maintenance personnel responsible for these aircraft are the operationally affected parties. The aircraft serial-number ranges in Paras 3-6 create a narrower subset of aircraft requiring specific fluid conversions or system modifications: for example, Para 3 targets SA226-T s/nos T201 to T287; SA226-AT s/nos AT001 to AT066; SA226-TC s/nos TC201 to TC247 when MIL-H-5606 is used. Para 4 and Para 5 spell out separate overlapping and expanded serial ranges for hydraulic and oxygen system modification requirements, respectively, with differing S/N windows and model lists.

Maintenance providers will have to remove crew seats and glareshields to access wiring, consoles and plumbing (Para 1 A, J), and they will need competence in pressurised hydraulic and brake system inspections (Para 1 C, E, F) and oxygen-system leak detection using MIL-L-2556713 or equivalent per the Fairchild Maintenance Manual (Para 1 H). Persons performing Para 2 work must follow Fairchild SB No 24-021 and SB24-03, which suggests the need to source service bulletin instructions and possibly parts (Para 2). Where hydraulic fluid replacement is required (Para 3), procurement and correct placarding of fluid reservoirs is necessary. Modification Paras 4 and 5 direct compliance with specific Fairchild Service Bulletins revised 19 July 1985, so affected operators must either perform those SB-specified modifications or otherwise comply with the inspection regime where allowed.

Regulatory actors are the Civil Aviation Safety Authority, under the Civil Aviation Regulations 1998 Part 39 airworthiness framework, which issues and records the AD (header). While the Directive does not list monetary penalties, it imposes mandatory safety duties on operators and maintenance organisations; failure to comply would be non-conformity with an AD issued under Part 39.

Supply-chain parties are indirectly affected. For example, parts for phenolic insulators, spiral wraps, replacement hoses, hydraulic fluid MIL-H-83282 and applicable placards, and the Fairchild SB and Service Note documentation are required inputs. The note in the Background that changes were made on aircraft manufacturer recommendation indicates manufacturer engagement in the scope of work. Finally, the Directive identifies different obligation scopes depending on whether the aircraft has been modified and whether it is fitted with anti-skid brakes, which creates differing compliance pathways for the same type certificate holders and could affect operators' maintenance planning and capital choices.

Duties are explicit and prescriptive. Under Para 1 the operator or maintenance organisation must: remove both crew seats and necessary access panels to gain access to left and right console areas (Para 1 A); inspect circuit breakers, wiring, and wire terminals in each console for security, chafing, foreign matter, support or any other unsatisfactory condition (Para 1 B); inspect hydraulic tubing with the system pressurised for leaking, chafing, security and evidence of fatigue, and inspect support assemblies, opening the hydraulic fluid containment bag where required (Para 1 C); inspect the front pressure bulkhead area and brake reservoir vent for hydraulic fluid contamination and clean as necessary (Para 1 D); inspect hydraulic system pressure gauge and tubing for security and chafing with the system pressurised (Para 1 E); inspect brake master cylinder flexible hoses with the brake system pressurised (Para 1 F); check parking brake valve and cable for correct operation and condition (Para 1 G); visually check oxygen lines for separation from moving components and for leakage using specified leak detector solution and maintain minimum clearances (Para 1 H); ensure electrical cable looms near rudder pedals have adequate clearance through full range of travel (Para 1 I); remove the instrument panel glareshield and inspect wiring, plumbing and equipment behind the panel (Para 1 J); inspect instrument panel subpanels and associated attachments for condition and clearance (Para 1 K); inspect electrical cables near cockpit side panels and maintain desirable or minimum clearances between oxygen tubing and electrical wires (Para 1 L); and correct all discrepancies and remove hydraulic fluid contamination before further flight (Para 1 M).

Para 2 imposes a duty to inspect the generator control junction box J-box area and install a phenolic insulator and spiral-wrap cables according to Fairchild SB No 24-021 (SA226) or SB24-03 (SA227). Para 3 requires draining and purging main hydraulic fluid for specified serial-number aircraft using MIL-H-5606, and updating reservoir placards to MIL-H-83282. Paras 4 and 5 require modification of the hydraulic and oxygen systems respectively in accordance with Fairchild SB revisions dated 19 July 1985, for specified serial-number groups, with a note to inspect and possibly replace cushion clamps when changing hydraulic lines. Para 6 requires inspection, rerouting, repair or replacement of "sceet" hoses in side consoles per identified Service Notes.

Rights are implicit and limited to procedural choices that the AD allows. The Directive offers an alternative compliance pathway: aircraft modified per Paras 4 and 5 and fitted with anti-skid brakes are exempt from the Para 1 repetitive inspections; aircraft modified per Paras 4 and 5 but without anti-skid brakes are only subject to inspection D of Para 1 (Compliance). Operators therefore have the right to choose to perform the specified system modifications (and install anti-skid where relevant) to alter ongoing inspection obligations. The Directive also acknowledges prior compliance: work done in accordance with the original AD counts toward the current AD, and compliance with earlier paragraphs of a previous issue constitutes compliance with those paragraphs in this issue (Note).

Timing duties are explicit. Initial compliance windows are specified: Para 1 inspections within 65 hours time in service after 31 May 1984 unless already done, then at intervals not exceeding 260 hours; Para 2 within 65 hours after 31 May 1984; Para 3 within 30 hours after 12 November 1983; Paras 4 and 5 before further flight after 31 December 1985; Para 6 within 65 hours after 31 December 1985 and then (<=) 260 hours intervals. Finally, the Directive requires correction before further flight where leaks or contamination are discovered (Para 1 H, M).

The Directive is issued within the Civil Aviation Regulations 1998 Part 39 airworthiness framework and appears under the Civil Aviation Safety Authority Schedule of Airworthiness Directives header. The document itself does not set out monetary or criminal penalties, nor does it specify enforcement processes or sanctioning mechanics; it records mandatory obligations and compliance times. Because it is an airworthiness directive under Part 39, the requirement to comply is regulatory and non-discretionary in effect for the affected aircraft and operators. The source text does not enumerate the administrative or criminal penalties for non-compliance, or the enforcement procedures CASA will apply.

Enforcement mechanisms implied by the document are administrative and operational: the Directive prescribes work that must be accomplished within specified timeframes and that certain discrepancies must be corrected before further flight (Para 1 M). This creates a duty that affects airworthiness status; aircraft not complying with an AD cannot be considered in conformity with that AD and therefore may be grounded or restricted until work is done under typical regulatory enforcement practice. The Directive explicitly cross-references FAA ADs and Fairchild service documents, signalling regulatory alignment and identifying actions recognised internationally (Note and Paras 2-6 references). The document contains specific compliance windows and conditional reliefs tied to particular modifications and configurations; those conditional reliefs create a compliance status that is verifiable on inspection or maintenance records.

Operational enforcement will likely be through assessment of maintenance records and physical inspection against the AD requirements. The Directive requires removal of seats and glareshields for inspections, installation of insulators and wraps, hydraulic fluid purging and placard change, and system modifications per Fairchild SBs, all of which leave traceable maintenance actions and parts changes. The Directive requires that discrepancies and hydraulic contamination be corrected before further flight, producing a clear operational prohibition on continued flight where contamination or unsafe conditions are present (Para 1 M). The AD text does not describe appeal processes, rectification notices, or civil penalty schedules; those processes would be governed by the broader Civil Aviation Regulations and CASA administrative practice, which are not detailed in the source document.

The Directive is issued under and sits within the Commonwealth of Australia Civil Aviation Regulations 1998, Part 39 airworthiness directive regime, as shown in the Schedule heading. As drafted, it takes effect by imposing mandatory maintenance, inspection and modification requirements on affected aircraft; those obligations become part of the regulatory compliance matrix operators must observe under the broader aviation safety regulatory regime. The AD explicitly references and integrates manufacturer service documentation (Fairchild Service Bulletins and Service Notes) by requiring actions "in accordance with" those documents (Para 2, Para 4, Para 5, Para 6). That creates a direct regulatory dependency on the technical content of those service documents.

The Directive also cross-references FAA ADs 83-19-02 Amdt 39-4728, 84-05-01 Amdt 39-4822 and 85-04-01 Amdt 39-5005, indicating concurrent or related FAA regulatory actions (Note). The source document does not specify whether compliance with the referenced FAA ADs alone is sufficient, but it does indicate they are related reference material. The Directive clarifies that compliance with paragraphs 1 to 4 inclusive of the previous issue of this Directive constitutes compliance with paragraphs 1 to 5 of the current issue, which creates a retroactive recognition of prior compliance actions and an interaction between iterations of the AD (Note).

The AD mandates the use of specified military specification fluids and leak-detection agents as part of inspection and remediation work: MIL-L-2556713 for oxygen leak detection (Para 1 H), and a conversion from MIL-H-5606 hydraulic fluid to MIL-H-83282 for certain serial-numbered aircraft (Para 3). Those are technical standards; their application may require operators to comply with procurement, storage and handling requirements for those fluids under other regulatory regimes (for example hazardous goods handling), though the Directive itself does not elaborate those separate regulatory obligations.

Finally, the Directive instructs maintenance actions that may involve replacement parts, system modifications and placarding. The obligations to implement Fairchild Service Bulletins and Service Notes could require coordination between airworthiness regulators, designers or manufacturers if parts or modifications affect the type certificate or supplemental type certificates. The source text does not address approval pathways for alternative methods of compliance, engineering orders or minor design changes; consequently, any deviation from the specified service documents would likely require separate regulatory engagement consistent with Part 39 processes, not described in the Directive itself.

The document is labelled AD/SWSA226/47 Amdt 3, indicating this is the third amendment of the AD. The Background states that the Directive has been further amended to show the latest revision to the Requirement Documents and to introduce changes in the applicability. It also says repetitive inspections of "sceet" hoses located in the cockpit side consoles were added on the recommendation of the aircraft manufacturer to further reduce the possibility of cockpit fires. The Note explains that compliance with paragraphs 1 to 4 inclusive of the previous issue of this Directive constitutes compliance with paragraphs 1 to 5 of this issue.

Specific amendment actions included in Amdt 3 are the introduction of Para 6, which mandates inspection of "sceet" hoses per Fairchild Service Note 226-SN-145 dated 2 July 1985 for SA226 and Fairchild Service Note 227-SN-052 dated 2 July 1985 for SA227 (Para 6). The Requirement documents referenced by Paras 2, 4 and 5 are indicated as being revised; in particular, the service bulletins for hydraulic and oxygen system modifications are identified as "revised 19 July 1985" (Paras 4, 5). The AD also revises applicability and serial-number ranges for different inspection and modification requirements across Paras 3-5, suggesting that amendment 3 adjusted which serial numbers are subject to hydraulic fluid purging, hydraulic modification, and oxygen modification.

The compliance dates stated in the Directive reflect a sequence of prior AD activity: Para 3 uses an earlier compliance date of 12 November 1983, while Para 1 and Para 2 set initial compliance windows relative to 31 May 1984. Paras 4 and 5 set a "before further flight after 31 December 1985" deadline. These staggered dates indicate the AD has been updated across years and that earlier versions carried different deadlines or requirements for subsets of aircraft. The Note that earlier compliance with prior AD paragraphs counts toward compliance with this issue provides continuity for operators who already performed required actions under earlier amendments.

The Background specifically records the driver for amendment as manufacturer recommendation and the need to update requirement documents and applicability. No other historical detail or amendment rationale is provided in the source beyond that the additions aim to preclude the possibility of cockpit fires and to reflect revised service documents.

The source text contains no litigation history. It names no cases, provides no references to judicial review, appeals, prosecutions, or administrative disputes, and does not record any precedent or legal challenges to the Directive. The only external regulatory references are to FAA ADs and to Fairchild Service Bulletins and Service Notes. For litigation or adjudicative developments related to this AD or to the underlying safety issues, the source provides no information.

Given the absence of litigation material in the Directive text, practitioners seeking precedents, enforcement decisions, or interpretative rulings will need to consult CASA administrative records, court archives, or other contemporaneous documents outside this source. The Directive itself provides prescriptive technical instructions and compliance deadlines, but no record of legal proceedings, enforcement actions, or contested matters.

Precision in applicability is material. The Directive contains multiple overlapping serial-number ranges for different actions (Paras 3-6). Operators must match their aircraft model and serial number exactly to the ranges listed. For example, Para 3 covers SA226-T s/nos T201 to T287; Para 4 covers SA226-T S/Nos T201 to T275 and T277 to T291 and other ranges; Para 5 has yet different S/N ranges that overlap and extend beyond Para 4 ranges. Misreading or misapplying these serial-number windows could produce either unnecessary work or failure to perform work that is mandated for that airframe.

Care is required on clearance dimensions. Para 1 H and L prescribes minimum and desirable clearance distances between oxygen lines and moving parts or electrical wiring: minimum 2 inches clearance from moving parts; desirable 6-inch clearance between oxygen tubing and electrical wires, with a fallback requirement to secure wires so they are not closer than 2 inches if 6 inches cannot be maintained. These are prescriptive and not advisory, so inconsistent practice could leave an operator non-compliant.

Configuration differences change obligations. If the aircraft has been modified in accordance with Paras 4 and 5 and is equipped with an anti-skid brake system, the Para 1 inspections are not applicable; however, if modified per Paras 4 and 5 but not fitted with anti-skid, only inspection D of Para 1 applies (Compliance). Failure to verify or document the presence of an anti-skid system could result in performing unnecessary inspections or, conversely, omitting required inspections.

Some inspections require pressurisation. Para 1 C, E and F require hydraulic and brake system inspections with the systems pressurised. That requires appropriate safety precautions, experienced personnel, and possibly test stands or operational checks. Para 1 C also instructs opening the hydraulic fluid containment bag to inspect lines; this step introduces contamination risk and requires suitable clean procedures, and Para 1 M mandates removal of any hydraulic fluid contamination before further flight.

Specified materials and methods are required. The oxygen leak check requires MIL-L-2556713 leak detector solution or an equivalent as specified in the Fairchild Maintenance Manual (Para 1 H). The Directive does not define acceptable equivalents other than referring to the Fairchild manual; practitioners must obtain and follow the Fairchild manual for equivalency guidance. Similarly, Para 3 requires specific hydraulic fluid conversion from MIL-H-5606 to MIL-H-83282 and placard changes, so procurement and correct marking of reservoirs are mandatory.

Service documents are normative. Paras 2, 4, 5 and 6 direct actions "in accordance with" Fairchild SBs and Service Notes, some dated or revised on 19 July 1985 or 2 July 1985. If operators do not have the correct revision of these documents or cannot source parts specified in them, they must obtain the referenced revisions to perform compliant work. Deviations from the content of those documents are not authorised by the AD text.

Timing windows are historical and specific. The compliance dates are tied to 1983-1985 calendar dates and to time-in-service windows measured from those benchmarks. For example, Para 1 initial inspections were to be done within 65 hours time in service after 31 May 1984 unless already done under the original AD; recurring intervals are 260 hours. Practitioners dealing with these requirements today must interpret the historical compliance windows and confirm whether their aircraft have already satisfied the work under earlier AD issues. The Note that prior compliance with earlier AD paragraphs constitutes compliance with current paragraphs addresses this but requires documentary proof.

Finally, the AD references FAA ADs as related materials (Note). While those FAA ADs may inform inspection scope or parts, the Directive does not accept FAA AD compliance as a substitute for its own requirements unless earlier compliance is demonstrably equivalent under the specified paragraphs, so careful cross-referencing is required.

Follow the Directive's prescriptive sequence, referenced service documents, and timeframes. Minimum steps, grounded in the AD text, are:

1. Confirm applicability. Match the aircraft model and serial number against the Applicability section and serial-number-specific Paras 3-6. If previously modified or if work was done under earlier issues of this AD, gather the maintenance records demonstrating compliance, because the Note indicates certain previous compliance counts toward current requirements.

2. Perform Para 1 work within the stated initial window. Unless previously done in accordance with the original AD, carry out the Para 1 inspections within 65 hours time in service after 31 May 1984, and thereafter at intervals not exceeding 260 hours time in service (Compliance). The Para 1 tasks consist of:

   • Remove both crew seats and access panels to reach left and right console areas (Para 1 A).
   • Inspect circuit breakers, wiring and terminals for security, chafing, foreign matter, support or other unsatisfactory conditions (Para 1 B).
   • With hydraulic system pressurised, inspect hydraulic tubing, support assemblies and open the hydraulic fluid containment bag to inspect hydraulic lines (Para 1 C).
   • Inspect front pressure bulkhead area, especially brake reservoir vent, for hydraulic contamination and clean as necessary (Para 1 D).
   • Inspect hydraulic system pressure gauge and tubing with the system pressurised (Para 1 E).
   • Inspect brake master cylinder flexible hoses with brake system pressurised (Para 1 F).
   • Check parking brake valve and cable (Para 1 G).
   • Visually check oxygen lines for separation and for leakage using MIL-L-2556713 leak detector or an equivalent as specified in the Fairchild Maintenance Manual; maintain minimum clearances and correct leaks prior to further flight (Para 1 H).
   • Ensure cable looms near rudder pedals have adequate clearance throughout pedal travel (Para 1 I).
   • Remove instrument panel glareshield and inspect behind the panel (Para 1 J).
   • Inspect instrument panel and subpanels, plumbing, wiring and components for condition and clearance (Para 1 K).
   • Inspect electrical cables near cockpit side panels and maintain the 6-inch desirable clearance, or secure wires to be at least 2 inches from oxygen tubing if 6 inches is not achievable (Para 1 L).
   • Correct all discrepancies and remove hydraulic fluid contamination found, before further flight (Para 1 M).

3. Install J-box protection. For generator control junction box issues, inspect cables and terminals within and below the J-box, and install a phenolic insulator on the side of the J-box and spiral wrap on cables per Fairchild SB No 24-021 (SA226) or SB24-03 (SA227). Complete this within 65 hours time in service after 31 May 1984 unless already done (Para 2).

4. Drain and purge hydraulic fluid where required. For aircraft in the serial ranges and using MIL-H-5606 specified in Para 3, drain and purge the main hydraulic fluid and change the placards on both reservoirs to specify MIL-H-83282 within 30 hours time in service after 12 November 1983 (Para 3).

5. Modify hydraulic and oxygen systems per SBs. For aircraft listed in Para 4 and Para 5, perform hydraulic system modification per Fairchild SB No. 226-29-005 revised 19 July 1985 and oxygen system modification per Fairchild SB No. 226-35-003 revised 19 July 1985 respectively, before further flight after 31 December 1985. When changing hydraulic lines, inspect cushion clamps and replace as necessary (Para 4 note).

6. Inspect "sceet" hoses. Inspect "sceet" hoses in side consoles for condition and security and reroute, repair or replace as necessary in accordance with Fairchild Service Note 226-SN-145 (SA226) and 227-SN-052 (SA227). Initial inspection within 65 hours time in service after 31 December 1985 and thereafter at intervals not exceeding 260 hours time in service (Para 6).

7. Use specified materials and methods. For oxygen leak checks use MIL-L-2556713 leak detector solution or an equivalent as the Fairchild Maintenance Manual specifies (Para 1 H). For hydraulic fluid conversion use the specified MIL-H-83282 and update placards accordingly (Para 3). Follow the exact revisions of Fairchild SBs and Service Notes cited, which are treated as requirement documents in the Directive (Paras 2, 4-6).

8. Document and correct before flight. Correct any discrepancies and remove hydraulic fluid contamination before further flight as mandated (Para 1 M). Keep records to demonstrate that inspections, modifications and placard changes required by the AD have been completed, and retain service bulletin references and revision dates used to perform the work, as the Note and Background treat prior compliance as potential satisfaction of current requirements.

9. Use conditional relief appropriately. If the aircraft has been modified in accordance with Paras 4 and 5 and is equipped with an anti-skid brake system, the Para 1 inspections are not required; if modified but without anti-skid, only Para 1 D applies. Verify and document modification status and anti-skid equipment to substantiate any relief from repetitive inspection obligations (Compliance).

10. Coordinate with manufacturer documents and regulatory guidance. Obtain and apply the Fairchild Service Bulletins and Service Notes named in the Directive and ensure work is performed to the revisions specified. Where an operator contemplates an alternative method of compliance or equivalent procedure, engage with CASA under Part 39 processes, noting that the Directive itself requires actions "in accordance with" the referenced service documents.

These steps derive directly from the language of the Directive paragraphs and compliance section. Where the Directive requires specific testing solutions, fluid types or service bulletin revisions, obtain the exact items and document their application to support compliance evidence.