AD/CIRRUS/6 - Brake Caliper Piston O-Ring Seals

Airworthiness Directive (AD). An AD is a legally enforceable directive issued by CASA under the Civil Aviation Act 1988. It mandates corrective action on aircraft or aircraft components that have been found to pose an unsafe condition. Compliance is not optional; failure to comply renders the aircraft unairworthy and may expose the operator to enforcement action.

Group definitions. The AD partitions the affected aircraft into four groups by model and serial number. Group 1 covers SR20 aeroplanes S/N 1005-1600; Group 2 covers SR22 S/N 0002-1739; Group 3 covers SR20 S/N 1005-1592; Group 4 covers SR22 S/N 0002-1727. Notice that Groups 1 and 3 overlap on the SR20 range 1005-1592, but the requirements for those groups differ. Groups 2 and 4 overlap on SR22 S/N 0002-1727, again with different obligations. The overlap means that a single aircraft may fall into both a Group 1/2 and a Group 3/4 category, and therefore must satisfy requirements from both sets.

O-ring seals. These are elastomeric seals within the brake caliper pistons. Overheating can degrade them, leading to hydraulic fluid leakage. The AD requires replacement of these seals if no record of replacement at the last annual or 100 hour inspection exists.

Temperature indicator sticker. A sticker that changes colour (turns black) when exposed to temperatures above a threshold. It is installed on the brake caliper to give a visual indication that the brake assembly has overheated. The AD requires this sticker to be fitted for Groups 3 and 4, and mandates that any time the O-ring seals are replaced due to overheating (sticker black), a new sticker must be installed before further flight.

MLG wheel fairing modifications. For Groups 3 and 4, the AD requires cutting inspection holes for viewing the temperature indicator sticker and trimming the fairing to prevent fluid entrapment. These modifications are intended to allow easy visual inspection of the sticker and to reduce the chance that hydraulic fluid collected in the fairing could contribute to a fire.

Pilot’s Operating Handbook (POH) revision. The AD requires inserting the correct revision part number into the POH, as specified in Table 1. This ensures that the operating limitations and procedures in the cockpit reflect the modified configuration. The part number corresponds to a specific revision level of the handbook approved by the FAA.

Service Bulletins. The AD mandates that certain actions must be performed in accordance with specific Cirrus Design Corporation Service Bulletins (SB 2X-32-13R1 for O-ring/caliper replacement, and SB 2X-32-14R1 for fairing modifications and sticker installation). These bulletins provide the detailed instructions. The AD allows use of later FAA approved revisions of these bulletins, meaning the manufacturer can update the procedures without requiring a new AD.

Compliance times. The AD uses two main compliance metrics: within 50 hours TIS after the effective date (for records check, fairing modifications, sticker installation, POH revision) and before further flight (for corrective action after a failed records check, and for sticker replacement after an overheating event). “Within 50 hours TIS” gives operators a short window of flight time to schedule the work, whereas “before further flight” is immediate and can ground the aircraft.

The AD directly affects any person or entity that owns, operates or maintains a Cirrus Design SR20 or SR22 aeroplane falling within the listed serial number ranges. This includes private owners, flying schools, charter operators, corporate flight departments, aircraft maintenance organisations, and any other entity that has custody or control of such an aircraft. Because the AD is addressed to “the owner/operator” in practice (though not explicitly in the text), the duty to ensure compliance rests primarily on the registered operator, who is usually the person responsible for maintaining the aircraft in an airworthy condition.

The AD also indirectly affects aircraft sellers and buyers. When an aircraft subject to this AD is sold, the seller must disclose whether the AD actions have been completed and recorded. A purchaser would be wise to verify compliance during pre-purchase inspection, because non-compliance could ground the aircraft immediately. The AD can affect the aircraft’s resale value: if the mandatory modifications have not been done, a buyer will discount the price to cover the cost of compliance. Conversely, an aircraft that has all ADs up to date may command a premium.

Part manufacturers and repair stations are also affected. Cirrus Design Corporation is the manufacturer referenced in the service bulletins. Maintenance providers must be familiar with the relevant service bulletins, have access to the parts (O-ring kits, new calipers, temperature indicator stickers, fairing modification kits), and be authorised to perform the work (e.g., appropriately rated LAME or AMO). The AD does not require CASA approval for alternative means of compliance; it mandates following the specified service bulletins or their later FAA-approved revisions. That limits flexibility for maintainers to deviate from the prescribed method.

Insurance companies may factor AD compliance into risk assessment and premium setting. An operator who cannot demonstrate compliance may face higher premiums or coverage denial after an incident. Additionally, any accident or incident involving brake failure or fire could trigger an investigation into whether the AD had been complied with, with potential liability implications.

The Australian public is indirectly affected to the extent that ADs reduce the probability of an aircraft accident caused by brake failure. However, the cost of this safety improvement is borne directly by the private operators. For commercial operators, those costs are likely passed on to customers through higher charter rates or training fees, meaning that the wider flying community shares the economic burden.

Duty to check maintenance records. For Groups 1 and 2, the AD imposes a duty on the operator to check the aircraft’s maintenance records at the next annual or 100 hour inspection to ascertain whether the brake caliper piston O-ring seals were replaced at the last such inspection. This must be done within 50 hours TIS after the effective date. If the records show replacement, no further action is required under this requirement; if they do not, the duty escalates.

Duty to replace O-ring seals or brake calipers. If the records check reveals that the O-ring seals were not replaced at the last annual or 100 hour inspection, the operator must, before further flight, either replace the O-ring seals with new ones or replace the old brake calipers with new calipers. The work must follow Service Bulletin SB 2X-32-13R1 (or later FAA approved revision). There is no option to ignore this or to defer it beyond the next flight.

Duty to modify wheel fairings and install temperature indicator stickers. For Groups 3 and 4, the operator must, within 50 hours TIS, modify the MLG wheel fairings to add inspection holes and trim them to prevent fluid retention, and install a temperature indicator sticker on each brake caliper. These must follow SB 2X-32-14R1. There is a continuing duty: anytime the O-ring seals are replaced due to overheating (sticker black), a new sticker must be installed before further flight.

Duty not to install unmodified fairings or calipers. The AD prohibits installing any MLG fairing without the required modifications, and prohibits replacing any brake caliper without also installing the temperature indicator sticker. These prohibitions take effect from the effective date of the AD.

Duty to revise the POH. For all affected aeroplanes, the operator must insert the appropriate Revision A6 part number into the POH as per Table 1, within 50 hours TIS. The POH is a required document for flight; having an incorrect revision could technically render the aircraft documentation non compliant, though the AD does not explicitly say the aircraft may not be operated without the revision. The practical effect is that the POH must be updated.

Rights. The AD does not explicitly confer any rights on operators. There is no provision for applying for an alternative method of compliance or an extension of compliance time. However, because the AD references “later FAA approved revision” of the service bulletins, the operator may choose to use a later version that may be more convenient or cost effective, provided it is FAA approved. There is no stated right to use a different manufacturer’s parts or procedures. The AD is modelled on the FAA AD 2006-21-03, so any later FAA approval of a revision is implicitly recognised.

Right to rely on previous compliance. Where the AD says “unless already done”, an operator who can prove (through maintenance records) that the required action was performed before the effective date need not repeat it. This avoids duplication of cost.

No right to avoid compliance. The AD does not permit an operator to choose not to comply, even if they accept the risk. Operating the aircraft without compliance would be a breach of civil aviation regulations.

The AD itself does not specify penalties, but as a legally binding instrument under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations (CASR), non-compliance can attract significant sanctions. Enforcement is the responsibility of CASA, which may take a range of actions.

Under the Civil Aviation Act, a person who contravenes an airworthiness directive may be guilty of an offence. Penalties can include fines (currently up to several thousand penalty units for individuals, and higher for bodies corporate). More practically, CASA can issue a direction to ground the aircraft, suspend or cancel the aircraft’s certificate of airworthiness, or impose conditions on its operation. In serious cases, CASA can seek court injunctions or take enforcement action that may lead to criminal prosecution if the non-compliance contributed to an accident.

The AD’s use of “before further flight” language for several requirements means that if an operator continues to fly after the compliance deadline, each flight could constitute a separate contravention. This raises the potential for accumulating fines and demonstrates the seriousness that CASA places on immediate corrective action.

An operator who is found to have falsified maintenance records to show compliance when it was not performed could face more severe penalties, including prosecution for fraud.

In practice, CASA often detects non compliance during routine surveillance, maintenance record audits, or after an incident. The requirement to insert the POH revision part number provides an additional visible indicator of compliance: an inspector can quickly check the POH to see if the correct part number is present.

It is worth noting that the AD is derived from FAA AD 2006-21-03. In the United States, non compliance with an FAA AD is a violation of federal regulations, and the FAA can impose civil penalties and even revoke an airman’s certificate. While Australian enforcement is independent, the origin of the AD in a foreign regulator’s finding of an unsafe condition may influence CASA’s enforcement posture.

Because an AD is mandatory, it overrides any conflicting provisions in an aircraft’s maintenance manual or operator’s procedures. An operator cannot use a slower schedule than that specified, even if their own maintenance program might otherwise allow it. The AD’s compliance times are minimum requirements.

This AD is issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations (CASR). It sits within the broader framework of Australian airworthiness regulation, particularly CASR Part 42 (Continuing Airworthiness) and Part 145 (Maintenance Organisations). Compliance with an AD is a condition of maintaining an aircraft’s certificate of airworthiness. If an AD is not complied with, the aircraft is not airworthy and may not be flown.

The AD specifically references FAA AD 2006-21-03 Amdt 39-14787. This indicates that the AD is adopted from a US Federal Aviation Administration airworthiness directive. The incorporation by reference of FAA approved revisions to the Cirrus service bulletins means that updates approved by the FAA are automatically acceptable under the Australian AD, without the need for a separate Australian approval. This reduces regulatory duplication but also means that Australian operators must monitor FAA actions that affect these bulletins.

The service bulletins themselves are not law; they are manufacturers’ instructions. By mandating compliance with them, the AD gives those instructions the force of law. Any later revision of the service bulletin that is FAA approved is automatically incorporated as a means of compliance.

The AD interacts with aircraft maintenance record requirements. CASR Part 42 requires that all maintenance, including AD compliance, be recorded in the aircraft’s maintenance records. The AD’s records check requirement for Groups 1 and 2 effectively reinforces this: if the O-ring replacement was not recorded, it is deemed not to have been done. This places a premium on accurate and upd records.

The POH revision requirement interacts with the aircraft’s flight manual, which is an approved document. Changing the POH part number effectively updates the flight manual to reflect the current configuration. Operating with an outdated POH could be a separate regulatory violation.

The AD does not explicitly mention interactions with state or territory laws, but brake fires could also engage workplace safety laws if the aircraft is used for commercial operations. If an operator fails to comply and a fire occurs, they could face additional liability under occupational health and safety legislation.

There is no explicit provision in the AD concerning international operations. If an Australian registered Cirrus is operated overseas, the local aviation authority may require compliance with its own equivalent AD. The Australian AD might be recognised through bilateral agreements.

The AD is a stand-alone instrument; it does not repeal or amend any other AD. However, it may interact with other ADs that affect the Cirrus SR20/SR22, such as those concerning the landing gear, wheels, or hydraulic system. Operators must ensure compliance with all applicable ADs, not just this one.

The source document for this AD shows no amendments. AD/CIRRUS/6, bearing the CASA number 13/2006, was issued on 25 October 2006 and became effective on 21 December 2006. It is the original and, as far as the source shows, the only version of this AD. There are no listed amendments or revisions within the document itself. The table of amendment history typically found in CASA advisory publications is not present in the supplied text.

However, the AD references service bulletins that may themselves be revised. The AD allows use of “later FAA approved revision” of SB 2X-32-13R1 and SB 2X-32-14R1. This means that even if the AD text remains unchanged, the technical requirements can evolve if Cirrus releases an updated bulletin and the FAA approves it. An operator relying on a later revision must ensure that revision is indeed FAA approved; the AD does not give CASA a separate approval role.

It is possible that CASA subsequently issued a superseding AD for the Cirrus brake issue, either to expand the applicability, change compliance times, or add new requirements. The supplied source does not indicate whether AD/CIRRUS/6 is still current or has been superseded. An operator should check the current CASA AD database for the latest status.

Amendment history of the parent US AD (FAA 2006-21-03) might also be relevant. The FAA could have later amended its AD, and those amendments might have been adopted by CASA through a new Australian AD or through a reference update. The source contains no information on that.

For practical purposes, this AD as presented is frozen in time as at its issue date. Compliance must be performed according to the version of the service bulletins specified or later FAA approved revisions. The AD does not include an automatic sunset or review date; it remains in effect until superseded or withdrawn.

Given the age of the AD (2006), most affected aircraft would have been brought into compliance long ago, unless they have been out of service. A buyer of an aircraft that has been stored should still verify compliance with this AD by checking the maintenance records.

The source document does not mention any litigation related to this AD. There is no reference to court cases, enforcement actions, or appeals. This does not mean that no litigation has ever occurred; it simply means that the text of the AD does not discuss any legal challenges. The AD is a regulatory instrument, and litigation typically arises from enforcement actions or negligence claims after an incident, not in the AD itself.

It is possible that an operator challenged the AD’s validity or the underlying FAA findings in a tribunal or court, but no such case is recorded in this source. Given the AD’s narrow scope and the safety justification (brake fires, loss of directional control), any legal challenge would likely have been difficult to sustain because CASA has broad powers to issue ADs to address safety issues, and the courts give significant deference to the regulator’s technical judgment.

If litigation did occur, it would most likely concern enforcement: CASA taking action against an operator for non compliance, and the operator defending on grounds such as impossibility of compliance, or arguing that the AD did not apply to their specific aircraft due to serial number overlap confusion. The overlapping serial number ranges between Groups 1 and 3, and 2 and 4, could create ambiguity: for example, an SR22 serial number 1700 falls in both Group 2 and Group 4? Actually Group 2 is 0002-1739, Group 4 is 0002-1727. So 1700 falls in both, and must comply with both sets of requirements. That seems clear, but an operator might miss the dual applicability. Such mistakes could lead to enforcement.

Another possible litigation area is product liability. If a brake fire occurred despite compliance with the AD, the manufacturer (Cirrus) could face claims that the AD did not fully address the unsafe condition. Conversely, if the AD’s prescribed modification caused a new problem, a lawsuit could arise. None of this is mentioned in the source.

For the purposes of this analysis, we can only say that the AD contains no litigation history. The user’s instruction is to ground every claim in the source, so we cannot speculate about later lawsuits. We simply note the absence of any such information in the document.

Overlapping group obligations. The most significant trap is that an aircraft may belong to two groups simultaneously. For example, an SR20 S/N 1200 is in both Group 1 and Group 3. That aircraft must comply with both Requirement 1/2 (records check and O-ring replacement) and Requirement 3 (fairing modifications and sticker). An operator who only follows the requirement for one group will be non compliant. The serial number ranges for SR22 also overlap: S/N 1500 is in both Group 2 and Group 4. The AD does not explicitly state that aircraft falling in overlapping ranges must satisfy both sets of requirements, but a plain reading of the applicability and requirements compels that conclusion.

Ambiguity about the records check. Requirement 1 says: “Check the maintenance records to determine whether the brake caliper piston O-ring seals were replaced at the last annual or 100-hour inspection.” It does not say what to do if the records do not clearly indicate whether the seals were replaced. If the records are ambiguous or missing, the safe interpretation is that the seals were not replaced, and the operator must proceed to Requirement 2. The risk is that an operator might incorrectly interpret ambiguous records as showing replacement and skip the required action, then later face enforcement.

Immediate grounding upon records check failure. Requirement 2 says: “Before further flight after the check required by requirement 1 of this AD.” This means that if during the check you discover no record of replacement, you cannot fly the aircraft again until O-rings or calipers are replaced. That could catch an operator off guard if they do the check during a routine maintenance visit but then need to fly the aircraft before parts arrive. The only way to avoid this is to have the parts on hand when doing the check, or to do the check only when you are ready to perform the replacement immediately.

Temperature indicator sticker replacement on each overheating event. Requirement 3b says: “Within 50 hours TIS after the effective date of this AD, unless already done, and thereafter before further flight anytime the O-ring seals are replaced due to overheating of the brake assembly (temperature indicator sticker turned black).” This imposes a recurring obligation: every time you replace the O-rings because the sticker indicates overheating, you must also replace the sticker before next flight. If you replace O-rings for reasons other than overheating (e.g., as part of annual inspection), the sticker does not need replacement, but the AD does not explicitly say that. You must be careful to document the reason for seal replacement.

POH revision part number specificity. Table 1 lists specific part numbers for different serial number ranges and modifications. For SR20 S/N 1005-1147 that have the 3,000 pound gross weight modification following SB 20-01-00, the POH part number is 11934-002. For SR20 S/N 1268-1739, it is 11934-003. The operator must match the exact configuration. Using the wrong part number could mean the POH does not reflect the aircraft’s current configuration. The AD does not mandate inserting the entire revised POH, only revising the part number. If the POH content itself is outdated, there may be separate regulatory issues.

No alternative methods of compliance. The AD does not provide a mechanism for an operator to propose an alternative method of compliance (AMOC) to CASA. For many CASA ADs, there is a process to request an AMOC, but this AD is silent. Possibly CASA relies on the service bulletins’ provisions for deviations, but the AD does not say that. An operator facing difficulty obtaining the specified parts would have limited options: they could seek a formal exemption under the Act, which is a heavier process. This lack of flexibility is a gotcha for operators who might want to use a different seal material or caliper brand.

Date of FAA approval. Table 1 gives the date of FAA approval for each POH part number: 18 January 2006. The AD was issued in October 2006, so those POH revisions were already approved. An operator using an earlier POH revision would need to update.

“Unless already done” trap. The phrase “unless already done” appears for Requirements 1, 3a, 3b, and 4. This is standard, but operators must have proof of prior compliance. If you bought an aircraft and the previous owner did the work but did not record it properly, you may have to repeat it. The burden is on the current operator to produce evidence.

Compliance with AD/CIRRUS/6 involves a series of steps that must be carefully coordinated with maintenance scheduling and records management. The following practical approach integrates the AD’s requirements.

Step 1: Determine applicability. Identify the aeroplane model and serial number. Confirm that the aircraft falls within one or more of the four groups. If the serial number is outside the listed ranges, this AD does not apply. If it is inside, note which groups apply. For an SR20 that falls in both Groups 1 and 3, you must comply with all requirements for both groups. Create a checklist for each required action.

Step 2: Preliminary records check (Groups 1 and 2 only). At the next annual or 100 hour inspection (or within 50 hours TIS after 21 December 2006, whichever comes first), review the maintenance records to see if the brake caliper piston O-ring seals were replaced at the last annual or 100 hour inspection. If the records clearly show replacement, note that in the AD compliance log and proceed with other requirements. If there is any doubt, treat the seals as not replaced.

Step 3: Replace O-ring seals or calipers if needed (Groups 1 and 2). If the records check indicates no replacement, you must before further flight either replace the O-ring seals or replace the entire brake calipers. Obtain Service Bulletin SB 2X-32-13R1 (or later FAA approved revision) and follow the instructions. Use genuine Cirrus parts or equivalent as specified. Ensure the work is performed by an appropriately rated LAME or AMO. After completion, record the work in the maintenance records, stating the SB revision used and the part numbers.

Step 4: Modify MLG wheel fairings and install temperature indicator stickers (Groups 3 and 4). Within 50 hours TIS, perform the modifications per SB 2X-32-14R1. This involves cutting inspection holes in the fairings and trimming them to prevent fluid entrapment. Install temperature indicator stickers on each brake caliper. Ensure the stickers are visible through the inspection holes. Document the work.

Step 5: Install stickers after future O-ring replacements due to overheating (Groups 3 and 4, ongoing). If at any time in the future you replace the O-ring seals because the temperature indicator sticker shows black (overheating), you must install a new sticker before the next flight. Record this each time.

Step 6: Revise the POH (all groups). Within 50 hours TIS, insert the correct part number into the POH as per Table 1. Obtain the Revision A6 insert from Cirrus or an approved source. Physically update the POH and record the revision in the aircraft’s continuing airworthiness records.

Step 7: Ensure prohibitions are observed. From the effective date, do not install any MLG fairing that has not been modified per Requirement 3a. Do not install any brake caliper without also installing the temperature indicator sticker. When ordering parts, confirm they are compliant.

Step 8: Record compliance in a dedicated AD status log. Create a log entry for each requirement, cross referencing the AD number, the requirement number, the service bulletin revision used, the date of completion, and the name of the person certifying the work. Keep this log with the aircraft’s maintenance records for inspection.

Step 9: Monitor for revisions. Check periodically whether Cirrus has released a later FAA approved revision of SB 2X-32-13 or SB 2X-32-14. If so, you may use it for future replacements, but for actions already completed, the earlier revision is acceptable. Also monitor whether CASA supersedes this AD with a new one.

Step 10: Before purchasing or operating a used aircraft. If acquiring an affected aircraft, review the AD status log. Verify that all requirements have been completed and documented. If not, factor the cost of compliance into the purchase price. Do not fly the aircraft until the AD is satisfied.

By following these steps, the operator will meet the legal obligations under the AD and maintain the aircraft’s airworthiness. The key is to not overlook the overlapping group requirements and to ensure that the before further flight deadlines are respected.