AD/A320/212 - Braking and Steering Control Unit

The central concept is the Braking and Steering Control Unit (BSCU) standard, which refers to the specific hardware and software configuration of the electronic unit that controls braking and nose wheel steering functions on these Airbus aeroplanes. The directive lists three pre-EMM standards: standard 7 (part number C20216332292C, installed by Airbus modification 24449 during production or by SB A320-32-1124 in service), standard 9 (C202163372D32, installed by modification 31106 during production or by SB A320-32-1227/1232), and standard 9.1 (C202163382D32, installed by modification 32500 during production or by SB A320-32-1254). These standards are superseded by standard 10, which is the only approved configuration after compliance.

Another key concept is the "lateral runway excursion" described in the background. This is classified as a hazardous event with a large reduction in safety margins. The failure mechanism involves a hardware failure in the BSCU that affects the monitoring function, including system reconfiguration management. This failure can cause a runaway of nose wheel steering, meaning the nose wheels deflect uncontrollably, which on landing can cause the aircraft to veer off the runway. The earlier French AD (F-1992-117-025(B) Revision 1) had attempted to address this by upgrading the steering logic, but the software change was insufficient to address the underlying hardware failure. BSCU standard 10 implements a different approach: improved system reconfiguration management when the failure is detected, presumably by detecting the failure and switching to a safe mode or preventing the runaway.

The concept of "reconfiguration management" relates to how the BSCU handles fault detection and system redundancy. The failure mechanism caused the monitoring function to be compromised, so the BSCU could not properly detect and reconfigure after a fault. Standard 10 apparently improves this detection and reconfiguration logic.

The directive also introduces a compatibility limitation: BSCU standard 10 is not compatible with Dunlop 46x16-20 tyres P/N 11659 T and 11661 T. The source does not specify the nature of the incompatibility, but it is likely related to physical interference or load rating issues with the new BSCU operating parameters. The service bulletin presumably details the reason.

The directive's applicability is limited to aeroplane models listed in Table 1, which includes various sub-models of the A319, A320 and A321 (e.g., A319-111, A320-212, A321-231). The directive only applies if these aeroplanes are equipped with one of the three pre-EMM BSCU part numbers. If an aeroplane already has BSCU standard 10 from production or a prior modification, this directive does not impose any new requirement. Similarly, if an aeroplane has a different BSCU (e.g., an EMM version), it is outside scope.

Compliance timing varies by requirement. Requirement 1 has a long lead time of about 17 months from the effective date (8 May 2008 to 30 September 2009). This allows operators to schedule the modification during routine maintenance or phased implementation. Requirement 2 is immediate upon completion of Requirement 1: before further flight. Requirement 3 is effectively immediate from the effective date for any aircraft that already has BSCU standard 10 installed, and continues as a permanent prohibition for any future installations.

The directive incorporates by reference the EASA-approved service bulletin. This means that any later revision approved by EASA is also acceptable. This gives some flexibility if the bulletin is updated, but also creates reliance on a foreign regulatory body's approval process. Operators must monitor EASA's approval status of any revisions.

The primary affected parties are operators of Airbus A319, A320 and A321 series aeroplanes that have one of the specified pre-EMM BSCU standards (7, 9 or 9.1). This includes commercial airlines, charter operators, freight operators, and any entity that owns or operates such aircraft under an Australian air operator's certificate or other authorisation, as the directive applies to Australian-registered aircraft and possibly to foreign aircraft operating in Australia under certain conditions. The directive applies to all aeroplane models listed in Table 1: A319-111 through A319-133, A320-111 through A320-233, and A321-111 through A321-232 (with some gaps in the list presumably covered by the inclusive ranges). Essentially, it covers the entire family of A320ceo (current engine option) models that were in production or service at the time.

Maintenance organisations that perform work on these aircraft are also affected. They must have the capability to perform the modification or replacement in accordance with Airbus SB A32-32-1336, which may require specific tooling, training, and parts. The maintenance provider must ensure that the work is done correctly and that the appropriate certification (e.g., release to service) is issued.

Parts suppliers are affected. The directive prohibits the installation of Dunlop 46x16-20 tyres P/N 11659 T and 11661 T on aircraft with BSCU standard 10. This affects the demand for those tyre types. Suppliers who hold inventory of those tyres may see reduced demand, and operators with stocks of those tyres may need to write them off or sell them to operators of aircraft not subject to the directive (e.g., A320 models with standard 10 not yet installed? But note requirement 3 prohibits installation from effective date if BSCU standard 10 is already fitted; if the aircraft still has old standard, the tyre ban only applies after upgrade. So there is a window where the tyres could be used before upgrade). However, the effective date prohibition applies immediately to any aircraft that already has BSCU standard 10. So an operator that already upgraded to standard 10 before 8 May 2008 must immediately cease using those tyres.

The tyre manufacturer, Dunlop, is affected indirectly: two of its part numbers are prohibited on a large fleet of aircraft, which may reduce sales and require product support for alternative tyres.

Regulators and foreign regulatory bodies are affected indirectly. CASA has adopted this directive based on EASA's determination of an unsafe condition. The directive refers to EASA AD 2008-0048. This illustrates the international harmonisation of airworthiness directives. Other national aviation authorities may have issued similar directives, and operators must comply with each jurisdiction's requirements.

Lessors and financiers may also be affected. Aircraft subject to the directive may have reduced marketability or value until the BSCU upgrade is accomplished. The cost of compliance may be a factor in lease negotiations or maintenance reserve calculations.

The directive does not affect aircraft that are already equipped with BSCU standard 10 at the effective date, except for the tyre prohibition. Those operators must ensure no prohibited tyres are installed from 8 May 2008. Also, aircraft with post-EMM BSCU or other standards not listed are not affected.

The compliance deadline of 30 September 2009 gives operators about 17 months to schedule the work. This is a moderate timeline, but for large fleets it may require significant coordinated downtime. Operators must also factor in obtaining parts and scheduling maintenance slots. The tyre removal requirement is immediate upon upgrade, so operators must have replacement tyres available.

The directive imposes three key duties on the affected operator. First, the duty to modify or replace the BSCU with standard 10 in accordance with Airbus SB A32-32-1336 (original issue or later EASA-approved revision) before 30 September 2009. This duty is absolute; there is no exception for hardship, operational necessity, or economic infeasibility. The operator must schedule and complete the work by that date, using the prescribed method.

Second, upon completion of that modification or replacement, the operator has the duty to remove the two specified Dunlop tyre part numbers from the aeroplane before further flight. This duty triggers immediately upon the accomplishment of Requirement 1. The operator cannot defer the tyre removal even if the aircraft is about to depart; it must be done before the next flight. This imposes a logistical requirement: the operator must have appropriate replacement tyres available at the location where the BSCU modification is performed.

Third, from the effective date of 8 May 2008, the operator has a continuing duty not to install the prohibited Dunlop tyre part numbers on any aeroplane equipped with BSCU standard 10. This duty applies to all affected aircraft, regardless of when the BSCU standard 10 was installed. If an aircraft already has BSCU standard 10 before the effective date, the prohibition is immediate. If an aircraft is upgraded later, the prohibition applies from the upgrade date (and the removal duty also applies). The operator must ensure that its maintenance procedures and parts inventory prevent such installations.

The directive does not explicitly create rights for the operator. However, implicitly the operator has the right to use the service bulletin (including later revisions) as the approved means of compliance. The operator also likely has the right to apply to CASA for an alternative method of compliance (AMOC), although the directive does not mention this. Under standard CASA practice and CASR Part 39, an operator may request an AMOC if it can demonstrate an equivalent level of safety. The directive references EASA AD 2008-0048, so an AMOC issued by EASA for that AD may also be acceptable to CASA, but this is not stated in the source.

The operator does not have the right to defer compliance beyond the deadline without a specific extension from CASA, which would be unusual. Nor does the operator have the right to choose a different modification method not approved by EASA.

There is also no explicit duty on other parties, such as maintenance organisations or parts suppliers. However, in practice, maintenance providers must comply with the operator's instructions and perform the work in accordance with the approved data. Suppliers must not supply the prohibited tyres for installation on affected aircraft, though the directive does not directly impose duties on them.

The directive does not provide any compensation or reimbursement for compliance costs. The operator bears all costs.

The source does not specify penalties. However, as a CASA airworthiness directive, non-compliance is an offence under Australian law. Under the Civil Aviation Safety Regulations 1998 (CASR), specifically Part 39 (Airworthiness Directives), an airworthiness directive is a mandatory direction. Failure to comply with an airworthiness directive is an offence under regulation 39.001 and can attract civil penalties or criminal prosecution, depending on the wording. Typically, a contravention of an AD is a strict liability offence with maximum penalties for an individual of up to 50 penalty units (currently $15,500) per offence, and for a body corporate up to 250 penalty units ($77,500) or more, depending on the provision. Additionally, operating an aircraft that does not comply with an AD can lead to cancellation or suspension of the aircraft's certificate of airworthiness.

CASA may also take enforcement action under the Civil Aviation Act 1988, including issuing infringement notices (on-the-spot fines), remedial directions, or seeking injunctions to prevent flight. In serious cases, CASA may refer for prosecution.

The enforcement of the tyre prohibition (Requirement 3) is more straightforward: CASA could detect non-compliance during routine surveillance or ramp checks. If an aircraft with BSCU standard 10 is found with the prohibited tyres installed after 8 May 2008, the operator would be in breach.

The effective date (8 May 2008) triggers Requirement 3. Any installation of the prohibited tyres on an aircraft equipped with BSCU standard 10 after that date is immediately a breach. Operators cannot argue a grace period.

The directive does not specify any reporting requirements. However, under CASR, operators must keep records of compliance with ADs and make them available to CASA on request. CASA may also require an operator to submit a compliance schedule or notify completion.

In the aviation industry, the real enforcement mechanism is the denial of the right to fly. An aircraft that does not conform to an AD may have its airworthiness certificate suspended or be unairworthy. Operating an aircraft known to be unairworthy can attract severe penalties, including imprisonment for reckless endangerment under the Civil Aviation Act.

The enforcement burden falls on CASA's surveillance program. In practice, CASA may issue a direction to ground the aircraft until compliance is achieved. The operator may also face commercial consequences, such as loss of revenue, reputational damage, and potential termination of insurance coverage.

Given that the directive is adopted from an EASA AD, coordination between CASA and EASA may occur, but enforcement is domestic.

This airworthiness directive is issued under the powers granted by the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998 (CASR), specifically CASR Part 39 which governs airworthiness directives. It is a legally binding instrument that overrides any conflicting requirements in other CASA regulatory instruments unless specifically excluded.

The directive explicitly references EASA AD 2008-0048. This indicates that CASA has adopted the European directive, likely under a bilateral agreement or a unilateral recognition of EASA's safety determination. Operators should note that the EASA directive may have different applicability, compliance dates, or additional requirements not included in the Australian AD. The Australian AD only mandates compliance with the specified requirements as listed; it does not incorporate the entire EASA AD. However, the note states "EASA AD 2008-0048 refers". Operators may need to consult the EASA AD for background and for approved revisions to the service bulletin. The Australian AD states that later revisions of SB A32-32-1336 must be approved by EASA; this defers to EASA's approval process.

The directive interacts with the design approval and airworthiness standards. The service bulletin is likely an approved design change under EASA's Supplemental Type Certificate (STC) or modification approval. The BSCU standard 10, once installed, becomes part of the aircraft's type design. The directory does not specify whether the modification requires a new or amended aircraft flight manual supplement or other documentation.

The tyre prohibition interacts with other airworthiness requirements. The prohibited Dunlop tyres are presumably certified under other technical standard orders. Their removal may require the installation of alternative tyres that meet the aircraft's load and speed ratings. The operator must ensure that any replacement tyres are acceptable per the aircraft's maintenance manual and parts catalogue.

The directive also interacts with the operator's approved maintenance program. The BSCU upgrade must be recorded as an accomplishment. The service bulletin may impose recurring inspection or operational limitations for the new BSCU standard 10, which must be incorporated into the maintenance program. The directive does not mention any recurring actions.

International operations are affected. An Australian operator flying to countries that have not adopted the EASA AD may still need to comply with the CASA AD. Conversely, an Australian operator may need to comply with similar directives from other states. The directive does not address foreign aircraft operating in Australia; but under the Convention on International Civil Aviation, Australia may require foreign operators to comply with Australian ADs while in its territory. The applicability is limited to aeroplanes registered in Australia or operated under an Australian AOC. However, the directive text does not explicitly state its jurisdictional scope; it is assumed to apply to aircraft under CASA's regulatory remit.

The directive does not replace or modify the earlier French AD (F-1992-117-025(B) Revision 1); that directive may remain applicable unless superseded. However, since the Australian AD mandates a more comprehensive fix, compliance with this AD would likely satisfy the earlier requirement.

The directive does not affect any contractual relationships between operators and lessors or insurers, but it may become a term of compliance in lease agreements.

The source text is a single airworthiness directive AD/A320/212 dated 5/2008, issued on 6 March 2008 and effective 8 May 2008. There is no mention of any amendments to this directive. The directive appears to be a standalone issuance. It references an earlier French airworthiness directive F-1992-117-025(B) Revision 1, but that is a separate instrument, not an amendment.

The directive incorporates by reference Airbus SB A32-32-1336 original issue dated 19 September 2007, but allows later revisions approved by EASA. This means the service bulletin may be amended over time, but the directive itself has not been amended.

It is common for CASA to amend airworthiness directives, for example to extend compliance dates, correct typographical errors, or incorporate new information. However, no amendment is recorded in this source.

The directive was issued as part of a series; the numbering "5/2008" suggests it is the fifth AD issued in 2008 for this AD series (Airbus A320 family). The subject is "Braking and Steering Control Unit".

The directive was signed by David Punshon as a delegate of CASA on 6 March 2008. This signature and date mark the formal approval.

For the purposes of a deep dive, we must state that the source provides no amendment history. The directive stands as originally issued. There may be subsequent amendments (e.g., to extend compliance time for some operators), but we cannot speculate. Users should consult the current CASA database for any revisions to AD/A320/212.

The source text contains no reference to any litigation, court cases, or legal challenges related to this airworthiness directive. This is typical for routine ADs that address technical safety issues without immediate controversy.

Given that the directive was issued in 2008, it is now well past its compliance dates. Any litigation would likely have appeared in the early years after issuance, especially if operators challenged the basis or cost of the directive. However, we can find no mention in the source. CASA's decision to issue an AD is generally protected from judicial review on merits, but could be challenged on procedural grounds or for jurisdictional error. No such challenge is recorded in the source.

The 2005 lateral runway excursion that triggered the directive may have led to separate legal proceedings (e.g., between the operator and Airbus or component manufacturers), but that is outside the scope of this AD.

The absence of litigation in the source does not guarantee none exists, but we can only report what is in the source. Accordingly, we note that the text does not discuss any litigation history.

Several aspects of this directive could trip up operators or compliance personnel. The most significant gotcha is the interaction between Requirements 2 and 3. Requirement 3 prohibits installation of the specified Dunlop tyres on any aeroplane equipped with BSCU standard 10 from the effective date (8 May 2008). However, Requirement 2 only requires removal of those tyres after the BSCU upgrade is accomplished (Requirement 1). This means that between 8 May 2008 and the date of upgrade, an aircraft with old BSCU standard (7/9/9.1) could still have those tyres installed. But if the operator upgrades the BSCU on an aircraft that already has those tyres, they must be removed before next flight. However, what if the aircraft already has BSCU standard 10 before the effective date? Then Requirement 3 kicks in immediately, and those tyres must not be installed after 8 May 2008. But there is no explicit requirement to remove them if they were already installed before the effective date. The source says "Dunlop 46x16-20 tyres P/N 11659 T and 11661 T may not be installed on any aeroplane equipped with a BSCU standard 10" (emphasis added). The word "installed" in the present tense could be interpreted as a prospective prohibition only: from the effective date, those tyres cannot be newly installed. It does not explicitly say "must be removed" for existing installations. Requirement 2 only applies after Requirement 1 is accomplished. So an aircraft that had BSCU standard 10 and those tyres installed before 8 May 2008 might technically be allowed to keep them, as the prohibition only applies to installation, not continued installation. This is a subtle point. But the service bulletin notes incompatibility, so continued use would be unsafe. However, the legal language of Requirement 3 uses "may not be installed", which is ambiguous. A conservative operator would remove them immediately.

Another gotcha: the directive requires that the modification or replacement of the BSCU be done in accordance with SB A32-32-1336, original issue or later EASA-approved revision. If an operator uses a later revision that has not yet been approved by EASA at the time of work, that would be non-compliant. Operators must check the approval status.

The directive is effective 8 May 2008, but Requirement 1 has a deadline of 30 September 2009. Operators must not defer this indefinitely; they must have a plan and may need to accomplish the work ahead of the deadline to secure maintenance slots.

The tyre prohibition in Requirement 3 is not linked to the upgrade deadline; it applies immediately from 8 May 2008 to any aircraft already equipped with standard 10. Operators with such aircraft must ensure they do not install those tyres after that date during tyre changes.

The directive does not specify record-keeping requirements, but under CASR Part 39, the operator must maintain a record of compliance with each AD, including the date, method, and parts used. Failure to keep proper records could be a violation separate from the AD itself.

The directive incorporates the service bulletin by reference. Operators must obtain and follow the full bulletin. The bulletin may include additional details that are not part of the directive, such as special tools, test procedures, or post-installation inspections. These are mandatory because the directive says "in accordance with the instructions given in SB A32-32-1336".

A potential trap: the directive says "modify or replace the BSCU". If the service bulletin provides both a modification kit and a replacement option, the operator must choose one. But if the bulletin requires a specific kit, the operator must use that.

Finally, the directive does not address applicability to aircraft that have already been modified to standard 10 before the directive's effective date via other means (e.g., as an operator-developed modification). Such modifications might not be considered compliant if they do not match the prescribed service bulletin. Operators in that situation should seek an alternative method of compliance from CASA.

Compliance with AD/A320/212 requires a three-step process, which should be integrated into the operator's maintenance planning and records.

Step 1: Identify all aeroplanes in the fleet that fall within the applicability. This involves checking each aeroplane's model against Table 1 and verifying the BSCU part number or standard. The BSCU part numbers are listed: C20216332292C (standard 7), C202163372D32 (standard 9), C202163382D32 (standard 9.1). If the BSCU is any of these, the aircraft is affected. If the BSCU is already standard 10 or a post-EMM version, it is not affected except for the tyre prohibition (Requirement 3) if standard 10 is already installed. The operator should create a register of affected aircraft.

Step 2: Schedule and accomplish the BSCU modification or replacement for each affected aircraft before 30 September 2009. The work must be performed in accordance with Airbus SB A32-32-1336 (original issue 19 September 2007 or later EASA-approved revision). The operator should obtain the current approved revision of the bulletin from Airbus or an authorized source. The modification may be accomplished during a scheduled maintenance input or as a standalone event. The operator must ensure that the maintenance organisation has the necessary capability, tooling, and training. After completion, the aircraft's records must be updated to reflect that the BSCU standard 10 is installed.

Step 3: Concurrently with the completion of Step 2 for each aircraft, remove any Dunlop 46x16-20 tyres P/N 11659 T or 11661 T from that aeroplane before further flight. The operator must have replacement tyres on hand that are compatible with BSCU standard 10. The service bulletin or the aircraft maintenance manual will specify acceptable tyre part numbers. The removed tyres must be marked as prohibited for use on aircraft with BSCU standard 10, or disposed of appropriately.

Step 4 (ongoing): From the effective date of 8 May 2008, ensure that no Dunlop 46x16-20 tyres P/N 11659 T or 11661 T are installed on any aeroplane equipped with BSCU standard 10. This applies to all aircraft that have BSCU standard 10, including those that were already equipped before the effective date and those that are upgraded later. The operator should implement a parts control measure to prevent ordering or installing those tyre part numbers for any aircraft with BSCU standard 10. The operator may choose to remove the tyres from all affected aircraft proactively, even if the BSCU upgrade is not yet done, to simplify compliance.

Records: The operator must maintain records demonstrating compliance, including the date of BSCU modification, the service bulletin revision used, part numbers of the new BSCU, and evidence of tyre removal/installation. These records should be kept in the aircraft's permanent maintenance records and made available to CASA upon request.

Alternative means of compliance: If the operator cannot comply with the directive as written (e.g., due to parts shortage or operational reasons), the operator may apply to CASA for an alternative method of compliance under CASR Part 39. The application should demonstrate that the proposed alternative provides an equivalent level of safety. The application should be submitted well before the compliance deadline.

The operator should also monitor for any amendments to the directive or revisions to the service bulletin. CASA may issue a subsequent directive that extends compliance times or modifies requirements. However, the operator cannot rely on speculation; compliance with the existing directive must be achieved by the deadlines.

For aircraft that are not yet to be upgraded, the operator must still comply with Requirement 3 from 8 May 2008: those tyres cannot be installed if the aircraft has standard 10. If the aircraft does not yet have standard 10, the tyre prohibition does not apply until the upgrade is done. However, the operator should avoid installing those tyres on any aircraft that might be upgraded later, because they would then have to be removed immediately upon upgrade, creating waste.

Cost estimation: The operator should budget for the BSCU kit/part, labour, possible downtime, and replacement tyres. The directive itself does not provide cost estimates. The operator should contact Airbus or approved maintenance providers for pricing.

Finally, the operator must ensure that all maintenance personnel are aware of the directive's requirements and the correct procedures. Training may be needed for the BSCU modification.