AD/ROTAX/22 Amdt 1 - Camshaft Hydraulic Tappet Wear

The central concept is the airworthiness directive (AD), a mandatory notice issued by CASA under the Civil Aviation Regulations to correct an unsafe condition. This AD is a continuing airworthiness requirement that operates as a law: it imposes duties that, if not followed, make the aircraft illegal to fly. The directive is focused on a specific unsafe condition: increased wear between the camshaft and the hydraulic valve tappets. The wear is detectable only by inspecting the magnetic plug for metal particles. The magnetic plug is a component in the engine lubrication system that collects ferrous debris; the AD sets a threshold of metal parts larger than 3 mm as the trigger for mandatory investigation and rectification. The directive uses terminating action as a concept: once the operator installs the improved parts kit (P/N 881.831 containing tappet P/N 854.095), the recurring inspection obligations cease. This is a one-off compliance cure. The AD also relies on incorporation by reference of technical documents: BRP-Rotax ASB-912-051 and ASB-914-034, both dated 13 October 2006, or later approved revisions. These documents specify the precise inspection procedure, including the interpretation of Figure 1 and Figure 2. An operator must obtain these documents to comply. The directive defines applicability not only by serial number range but also by modification history: engines that had camshaft or tappet replacement in the specified period are caught regardless of serial number. Conversely, engines fitted with the improved tappets (P/N 854.095) during production, or subsequently via the spare part kit, are exempt. The exemption is verified by modification number references listed on the engine release certificate: 85-05 for 912 A, F50-05 for 912 F, S34-04 for 912 S, and F45-04 for 914 F engines. The directive also introduces a concept of previous compliance credit: operators who complied with Requirement 2 of the original issue (the 5-hour/1 March 2007 inspection) are considered compliant with the equivalent requirement in this amendment. This prevents double inspection but also means that an owner who missed the original deadline cannot be forced to turn back time; the amendment simply says that past compliance is acceptable. The background section, though not legally operative, explains that the manufacturer introduced a new tappet that eliminates the need for inspections, so the amendment limits requirements to engines not fitted with that tappet. This illustrates that the AD is a dynamic instrument responding to part improvements.

The directive directly affects aircraft owners and operators who fly aircraft powered by Rotax 912 A, 912 F, 912 S or 914 F engines falling within the specified serial number ranges: Rotax 912 A engines serial number 4,410.681 to 4,410.712; 912 F engines 4,412.912 to 4,412.921; 912 S engines 4,923.263 to 4,923.380; and 914 F engines 4,420.595 to 4,420.637. Additionally, any engine on which the camshaft or hydraulic valve tappets have been replaced between 1 January 2006 and 1 December 2007 is caught, regardless of its original serial number. This secondary trigger creates a larger pool of affected engines: for example, an older 912 S with a higher serial number that had a replacement camshaft fitted during a repair in mid-2006 would be covered even though its serial number is outside the primary range. The directive also affects engine repair shops, maintenance organisations and mechanics who perform inspections or replacements. They must be familiar with the ASB documents, the 3 mm threshold, and the precise inspection procedure. They also bear liability if they fail to detect metal particles that later cause engine failure. Aircraft manufacturers and supplemental type certificate holders are indirectly affected because the installation of these engines was done either by the aircraft manufacturer or via supplemental type certificate modification. However, the AD places no direct duty on them. Parts suppliers who stock or distribute the P/N 881.831 kit (containing tappet P/N 854.095) will see increased demand as owners seek terminating action to escape recurring inspections. The directive also affects CASA itself as the regulator, which must manage compliance enforcement, record-keeping and potential responses to non-compliance. From a free-market perspective, the directive disproportionately burdens small aircraft owners who may use their aircraft recreationally or commercially. The inspection and potential rectification costs are direct compliance expenses not offset by any subsidy. Owners who had already fitted the improved parts before the effective date are exempt, giving them a competitive advantage over those with older engines. The directive also has a geographic dimension: it applies to Australian registered aircraft, but the engines are manufactured by BRP-Rotax in Austria; operators in Australia must comply with Australian law, which may conflict with or add to requirements in other jurisdictions. However, the directive supersedes EASA AD 2006-316-E, implying harmonisation with European standards. The 5-hour initial inspection deadline (originally 20 October 2006 but effectively already past) creates retrospective compliance obligations: an owner who bought an affected engine second hand in 2008 would still need to ensure the inspection was done or perform it immediately. This creates transaction costs and uncertainty for buyers of used aircraft.

The directive imposes four distinct duties. First, inspect the magnetic plug before further flight after the effective date (3 July 2008), unless the inspection was previously accomplished. This is a one-time initial duty tied to the amendment’s effective date, but note that Requirement 1 requires it before further flight after the effective date, regardless of any previous inspections. Second, repeat the inspection as detailed in Requirement 2: within 5 hours of operation after 20 October 2006 but not later than 1 March 2007, and thereafter at every oil change. The wording creates ambiguity: the 5-hour/1 March 2007 deadline is in the past, so an owner today would need to have complied by that date; if not, they are in breach. The note says previous accomplishment with Requirement 2 of the original issue is acceptable, but it does not say what happens if the owner missed that deadline. The safest reading is that the owner must still perform that initial inspection as soon as possible, but the text is not explicit. Third, investigate and rectify the cause of any metal parts greater than 3 mm detected during an inspection. This must be done before further flight. The duty does not specify the method of investigation; it relies on the ASB documents for the procedure. Fourth, do not install an engine listed in the applicability section unless the magnetic plug has been inspected per Requirement 1. This duty binds anyone installing an engine, whether the owner, a mechanic or a seller. The directive also creates a right to terminate the recurring duties by installing the P/N 881.831 kit. Once installed, the engine is no longer subject to the inspection requirements. This is a conditional right: the operator must purchase and install the kit at their own expense. There is no duty to do so; the operator may choose to continue with ongoing inspections indefinitely. However, if metal is detected during an inspection and the cause cannot be rectified without the kit, the operator would effectively be forced into the terminating action to return the engine to service. The directive also implies a right to rely on previous compliance by accepting past accomplishment of Requirement 2 from the original AD. An owner who has records showing the inspection was done within 5 hours after 20 October 2006 and before 1 March 2007 can claim compliance without repeating that step. There is no explicit right to appeal or request an alternative method of compliance (AMOC) within the text itself; however, CASA’s standard procedures for alternative compliance would apply under the broader regulatory framework. The directive does not confer any right to compensation for the cost of compliance or for grounding due to metal detection. The operator bears all costs.

The directive does not specify a penalty amount or enforcement mechanism; that is left to the general provisions of the Civil Aviation Regulations and the Civil Aviation Act 1988. As a legislative instrument, an airworthiness directive is legally binding. Operating an aircraft in contravention of an AD renders the aircraft unairworthy and its certificate of airworthiness invalid. The pilot-in-command and the operator face potential enforcement action. Under the Civil Aviation Regulations, it is an offence to operate an aircraft that does not comply with an airworthiness directive. Penalties can include fines of up to 50 penalty units (currently $13,750 for an individual, higher for a body corporate) per offence, plus possible court-imposed orders. CASA may also issue a direction to ground the aircraft, suspend the operator’s certificate, or take other administrative action. The practical effect is that non-compliance stops the aircraft from flying. The directive itself contains no civil penalty provisions, criminal penalties, or sanctions beyond making continued operation illegal. However, the directive does contain an important enforcement trigger: if metal particles greater than 3 mm are detected and the operator fails to investigate and rectify before further flight, that flight would be illegal. CASA could prosecute for each flight. The directive also places a duty on maintenance organisations: if they sign off an aircraft that has not complied with the AD, they may be liable for issuing a false maintenance release. The enforcement risk is highest for commercial operators who use the aircraft for hire or reward, as they have a higher duty to maintain compliance records. For recreational owners, the risk is lower but still real: a CASA audit or a post-accident investigation would uncover non-compliance. The directive does not create any whistleblower or self-reporting incentives; an operator who discovers past non-compliance cannot retrospectively fix it without facing potential enforcement. The terminating action (installing the kit) does not forgive past non-compliance; it only stops future obligations. An operator who missed the 1 March 2007 initial inspection is technically in breach even after installing the kit, though in practice CASA would likely treat installation as a cure. The cost of enforcement - both for CASA and for the operator - is a deadweight loss, but it serves to create a credible deterrent. From a free-market viewpoint, the penalty structure (fines, grounding) is a blunt instrument that does not differentiate between a minor paperwork error and a genuine safety risk. However, CASA has discretion in prosecution.

The directive explicitly states that it supersedes EASA AD 2006-316-E and the previous CASA AD/ROTAX/22 original issue. This means that any obligations under those earlier instruments are replaced by this amendment. Operators who had been complying with the EASA directive are now required to comply with the Australian version, though the substantive requirements are nearly identical. The directive also incorporates by reference two technical documents: BRP-Rotax ASB-912-051 and ASB-914-034. These become legally binding to the extent they are cited. Any later approved revision of those documents is also incorporated, creating a dynamic reference that changes without a new AD - operators must track revisions. The directive does not mention the Civil Aviation Act or Civil Aviation Regulations directly, but it is issued by a delegate of CASA under those laws. The AD must be read together with the airworthiness provisions of the Civil Aviation Regulations (specifically Part 4A or Part 42, depending on the age of the aircraft). It also interacts with any other ADs that apply to the same engine or aircraft. For example, if another AD requires a different inspection interval for the oil system, the stricter requirement would apply. The directive does not create any interaction with workplace health and safety laws, but the inspection and rectification work must be done by appropriately licensed engineers under the Civil Aviation Safety Regulations. The directive does not reference the Trade Practices Act or competition law, but the requirement to purchase the P/N 881.831 kit from BRP-Rotax (or its authorised distributors) may raise issues if the kit is priced monopolistically. There is no option for a competing design unless an STC holder develops an alternative. The directive also interacts with insurance contracts: an aircraft flown in non-compliance with an AD may have its insurance coverage voided for any claim. Similarly, a buyer purchasing an aircraft subject to an outstanding AD may have a claim for misrepresentation if the seller did not disclose non-compliance. The directive does not establish a private right of action, but non-compliance would be evidence of negligence in a civil suit. The directive may also be relevant to cross-border operations: if an Australian-registered aircraft flies overseas, the AD remains binding on the Australian operator, but the foreign state may also require compliance with its own version of the AD. If the foreign state does not recognise the Australian AD, the operator may face conflicting obligations. The directive does not harmonise with any New Zealand or US FAA AD, but the rotax engines are widely used and similar ADs likely exist elsewhere.

The source text is itself an amendment: it is identified as AD/ROTAX/22 Amdt 1, which amends the original AD/ROTAX/22. The original AD was likely issued in 2006 as CASA’s adoption of EASA AD 2006-0316 (renumbered 2006-316-E). The exact date of the original issue is not given, but the compliance dates refer to 20 October 2006 as the effective date of the original issue. The amendment was prepared on 22 May 2008 and takes effect on 3 July 2008. The amendment’s key change is narrowing the applicability to exclude engines fitted with P/N 854.095 hydraulic tappets, either at production (identified by modification numbers on the release certificate) or through installation of the P/N 881.831 spare part kit. The original AD had applied to all engines in the serial number ranges without that exclusion. The background explains that the manufacturer introduced a new tappet that does not require the inspections. Therefore, the amendment removes engines with that tappet from the mandatory inspection regime. This is a deregulatory change for those owners, reducing their compliance burden. The amendment also adds a note stating that engines with the improved tappets are not affected. The amendment does not change the inspection requirements themselves; it only updates the applicability and adds the terminating action concept. The original AD had no terminating action; operators were required to inspect indefinitely. The amendment introduced the ability to end recurring inspections by installing the kit. This is a significant change because it gives owners an option to escape the recurring cost. The amendment also refines the compliance language: Requirement 2 says “remains unchanged as detailed in the original issue”, implying that the wording is the same, but the structure is now clearer because the terminating action is separate. The amendment also adds Note 3 to confirm that previous compliance with Requirement 2 of the original issue is acceptable, avoiding duplication. There is no mention of any transitional period for operators who had already purchased the kit before the amendment. The amendment history shows that the AD is living instrument that evolves as the manufacturer improves parts. This is typical for ADs: they are not static. However, the amendment does not explain why the original AD did not include the terminating action from the start. Possibly the kit was not available in 2006.

The source text does not mention any litigation. No court cases are referenced, and there is no suggestion that the AD has been challenged in Australian courts. This is not surprising, as airworthiness directives are typically challenged only on procedural grounds, and the small number of affected engines (hundreds) makes broad litigation unlikely. The AD was issued by a delegate of CASA, which has statutory authority to issue ADs. Any judicial review would require showing that the decision was ultra vires, procedurally unfair, or unreasonable in the administrative law sense. The narrow and technical nature of the AD makes such claims difficult. There is no indication of any pending litigation or disputes over this specific AD. However, there may be civil cases arising from engine failures where the AD is relevant as evidence of the required standard of care. For example, if an engine failed because the magnetic plug was not inspected, and the operator had not complied with the AD, that would be powerful evidence of negligence. Conversely, if an engine failed despite full compliance, the AD could be used to show that the operator took reasonable precautions. There are no known Australian cases specifically on this AD, but the broader jurisprudence on airworthiness directives confirms they are binding and non-compliance is a per se airworthiness issue. The lack of litigation history suggests that most operators have chosen to comply rather than challenge the AD. The costs of litigation would exceed the cost of compliance (inspection or kit installation). The smaller owners would have little financial incentive to contest the AD in court. The fact that the amendment itself was issued after consultation (implied by the delegate signature) suggests the original AD may have been amended in response to feedback from industry, avoiding the need for litigation. The absence of litigation does not mean there is no controversy; it may simply mean that the compliance burden is manageable or that affected parties lack resources to sue. From an economic perspective, litigation is a social cost; the fact that it has been avoided is a net benefit, but it also means that any ambiguities in the AD have not been judicially resolved. For example, the interplay between the 2006 compliance date and the 2008 effective date could be litigated if a strict regulator attempts to prosecute an owner who bought an affected engine in 2009 without a record of the initial inspection.

Several features of this directive can trap the unwary. First, the retrospective compliance date: Requirement 2 refers to an inspection that must have been done “within 5 hours operation after 20 October 2006 but not later than 1 March 2007”. Any engine that has accumulated hours since that date without that inspection is technically in breach. The AD does not provide a “catch-up” provision; it simply says previous accomplishment is acceptable. An owner who buys an affected engine secondhand in 2024 with no records of that initial inspection faces an unclear situation: should they perform the inspection now (even though it is years late) or assume the engine is non-compliant? The safest course is to perform the inspection immediately, but the AD does not explicitly authorise that. Second, the before further flight trap: Requirement 1 requires the magnetic plug inspection before further flight after 3 July 2008. That means even if the owner just did the 5-hour inspection in 2007, they must do another one before the first flight after 3 July 2008. This is easy to miss if the owner thinks the 2007 inspection was sufficient. Third, the serial number ranges appear narrow, but the additional trigger for engines that had camshaft/tappet replacement between 1 Jan 2006 and 1 Dec 2007 significantly widens the net. An engine with serial number outside the listed ranges could still be covered. An owner must check the engine’s maintenance history, not just the data plate. Fourth, the modification number references for identifying engines with P/N 854.095 tappets are only on the engine release certificate, not on the engine itself. If the release certificate is lost, the owner cannot prove exemption. The operator might need to contact BRP-Rotax for records. Fifth, the ASB documents are not reproduced in the AD; the operator must obtain them separately. If the operator does not have access to ASB-912-051 or ASB-914-034, they cannot comply with the inspection procedure. The AD says “or later approved revision”, but the operator must ensure they have the correct revision. Sixth, the 3 mm particle threshold may be misinterpreted: the AD says “metal parts greater than 3mm” as detailed in Figure 1 and 2 of the ASB. But the ASB figures likely include dimensions and shapes. An operator measuring only the longest dimension might think a 2.9 mm particle is safe, but the ASB might define greater than 3 mm as any dimension exceeding 3 mm. The AD does not specify whether it is length, width, or diameter. The cross-reference is critical. Seventh, the terminating action is only valid if the kit P/N 881.831 is installed. It is tempting to assume that installing any hydraulic tappet P/N 854.095 (e.g., as a single part) suffices, but the AD specifies the full kit. The kit includes additional components. Eighth, the effective date of the amendment is 3 July 2008, but the AD itself says “This Amendment becomes effective on 3 July 2008”. However, the compliance wording for Requirement 1 says “Before further flight after the effective date of this AD”. That means any flight after 3 July 2008 must have the inspection done if not already accomplished. An aircraft that flew on 2 July 2008 without the inspection is not in breach; but if it flies on 4 July 2008 without the inspection, it is. Ninth, the directive does not provide any alternative method of compliance (AMOC) procedure. Operator cannot simply get an exemption from CASA without a formal AMOC, which is not mentioned. Finally, the oil change interval is not defined by the AD; operators must follow the engine manufacturer’s recommended oil change schedule. If oil changes are less frequent than the 5-hour inspection, the 5-hour requirement acts as a floor. After the terminating action is taken, no further oil change inspections are required.

Compliance requires a multi-step process tailored to the specific engine. Step one: determine applicability. Check the engine data plate for the model and serial number. If the engine is within the listed serial number ranges for its model, or if the camshaft or hydraulic valve tappets were replaced between 1 January 2006 and 1 December 2007, then the AD applies. Check also the engine release certificate for modification numbers 85-05, F50-05, S34-04 or F45-04. If those numbers are present, the engine is not affected. Also check if the engine has had the P/N 881.831 kit installed; if so, no further action. Step two: obtain the ASB documents. Contact BRP-Rotax or an authorised distributor for copies of ASB-912-051 (for Rotax 912 series) or ASB-914-034 (for Rotax 914 series), dated 13 October 2006 or later approved revision. These documents detail the magnetic plug inspection procedure. Step three: perform the initial inspection before further flight after 3 July 2008. Drain the oil or access the magnetic plug as per the ASB. Inspect the plug for metal particles. Remove any particles and measure them. If no particles larger than 3 mm are found, record the inspection and proceed. If particles larger than 3 mm are found, do not fly. Investigate the cause according to the ASB and rectify. This may involve disassembling the engine to inspect camshaft and tappets. Step four: establish a repeating inspection schedule. The AD requires an inspection within 5 hours of operation after 20 October 2006 and not later than 1 March 2007. If that deadline is past, the operator should still perform that inspection as soon as possible to bring the engine into compliance. Then inspect at every oil change thereafter. The oil change interval is not specified by the AD; follow the engine service manual. Keep a logbook entry showing compliance with each inspection, including the date, hours, result (no metal, or metal found and rectified). Step five: consider terminating action. To stop the recurring inspections, purchase and install the P/N 881.831 spare part kit from BRP-Rotax. This requires removing the cylinder heads to replace the hydraulic valve tappets and possibly the camshaft. The work must be done by a licensed aircraft maintenance engineer. After installation, record the part numbers in the engine logbook. The AD then no longer applies. Step six: maintain records. Keep all logbook entries, release certificates, and copies of the ASB documents. If selling the engine, provide these records to the buyer. The buyer will rely on them to prove compliance. Step seven: monitor for revisions. The AD incorporates later approved revisions of the ASB documents. If BRP-Rotax issues a new revision, the inspection procedure may change. Periodic checking of CASA’s airworthiness directive database is prudent. The cost of compliance includes labour for inspections (estimated 1-2 hours per inspection at a typical workshop rate of $150-$200 per hour, plus oil change costs if the inspection coincides with normal maintenance). The terminating kit cost may be $500-$1,500 depending on availability and currency exchange. For a recreational aircraft flying 100 hours per year with oil changes every 50 hours, ongoing inspection costs would be roughly $300-$800 per year plus possible downtime. The terminating action is a capital cost that eliminates these recurring costs after the first year.