AD/AS 355/60 Amdt 5 - Tail Rotor Blade Trailing Edge

First core concept is the “tail rotor blade trailing edge” as the component at risk. The background states that a separation of a trailing edge section occurred due to crack growth in the blade skin. That unbalance can cause tail rotor gearbox separation, which is a catastrophic failure mode. The directive addresses that specific failure mode. Second is the “ALF check”, meaning after last flight of the day. The inspection must be done at that point or, if multiple flights, at least every 10 flight hours. That is a recurring, short-interval inspection that imposes operational discipline on operators. Third is the reliance on the Eurocopter Alert Service Bulletin (ASB) No. 05.00.38 as the technical standard. The directive references Revision 2 for the inspection method and Revision 3 for the repair requirements, but also says “or later EASA approved revision”. That creates a dynamic obligation: if EASA approves a later revision of the ASB, the operator must use that later revision, even if CASA has not separately reissued this directive. Fourth are the Repair Sheets, specifically FR CN 376 and FR CN 453. These are French repair design sheets that define a specific repair procedure for blades with certain part numbers and serial numbers. The directive does not reproduce those sheets; operators must obtain them from the design approval holder (Eurocopter, now Airbus Helicopters) or via the ASB. Fifth is the concept of “Maintenance Release”. The directive requires that the AD be entered on the Maintenance Release as maintenance required. That entry triggers a legal obligation under the Civil Aviation Regulations to ensure the aircraft is airworthy before flight. Sixth is the distinction between “visually inspect” (a non-destructive check) and “repair” (a structural modification that restores airworthiness). Seventh is the role of the Pilot in Command. The directive permits a PIC to perform and certify the visual inspection, but only if they have been trained by an appropriately qualified person. That deviates from the usual rule that maintenance requires a licensed aircraft maintenance engineer (LAME). The PIC’s certification is limited to this specific visual inspection, not the repairs. Eighth is the incorporation by reference of an EASA Airworthiness Directive (EASA AD 2009-0039). The note says “EASA AD 2009-0039 refers”, meaning that the Australian AD is harmonised with the European AD. Operators must also be aware of the EASA AD, which may have different compliance times or additional requirements. Ninth is that the directive applies to specific part numbers only: 355A12-0031-01 through -14, 355A12-0040-00 through -08, and 355A12-0050-00 through -05. Other blades are not affected. Tenth is the compliance time structure: requirement 1 is ongoing (repetitive), requirement 2 is a one-off past deadline, and requirement 3 is a prohibition effective from 9 April 2009.

The directive directly affects operators of Eurocopter AS 355 helicopters. That includes commercial operators (e.g. charter, air taxi, medical, search and rescue), private owners, training schools, and any entity that leases or owns AS 355 models E, F, F1, F2, N and NP. It also affects maintenance organisations, both approved Part 145 and smaller operations that carry out maintenance under the operator’s own approval. The requirement for the visual inspection to be performed by the Pilot in Command (if trained) expands the pool of personnel who can carry out that task, which shifts some burden away from maintenance engineers. However, the repairs (requirement 2) and the installation prohibition (requirement 3) still require appropriately qualified maintenance personnel. Manufacturers (Eurocopter, now Airbus Helicopters) are affected indirectly because the ASB and repair sheets are their documents; they must keep those documents available and updated. The Australian Civil Aviation Safety Authority is affected as the regulator responsible for issuing and enforcing the directive. Any person importing or selling an AS 355 helicopter or tail rotor blade with the listed part numbers is affected by the installation prohibition: they cannot install a blade unless it has been inspected and repaired as required. The directive also affects insurers, who may condition coverage on compliance with all applicable ADs. Lessors and financiers may require proof of AD compliance as part of lease or loan agreements. The directive has an extraterritorial effect: it applies to any AS 355 helicopter on the Australian Register, and also to any foreign-registered helicopter operating in Australia under a permission or exemption, because the directive refers to the Civil Aviation Act. At the time of Amendment 5, no AS 355 NP helicopters were on the Australian Register, but the directive still affects any NP that enters the Australian Register later. The requirement to carry copies of the ASB and the directive in the aircraft imposes a paperwork burden on any flight crew using the PIC inspection option. Finally, suppliers of replacement blades are affected: they must ensure that any blade they supply with a listed part number has been inspected and repaired per the ASB, or the buyer will be prohibited from installing it.

The primary duty is on the operator or owner of an affected helicopter to ensure compliance with all three requirements. Under requirement 1, the duty is to perform the visual inspection at each ALF check and within each 10 flight hour interval. That duty is continuous and repetitive. Under requirement 2, the duty (as of 31 March 2009) was to accomplish the repair sheet instructions on specified blades. That is a one-off obligation, but if it was not done by that date, the helicopter is now non-compliant and cannot be flown until it is done. Under requirement 3, the duty is imposed on “no person” to install a listed blade unless it has been inspected and repaired per the ASB. That duty applies to any person, whether they are the operator, a maintenance organisation, a supplier, or a pilot installing a blade themselves. The directive also creates a duty to enter the AD on the Maintenance Release as maintenance required. That ensures traceability and triggers the pre-flight airworthiness check obligations under the Civil Aviation Regulations.

The directive confers a right on the Pilot in Command. The PIC may perform and certify the visual inspection, provided they have been trained to do so by an appropriately qualified person. That right is a limited derogation from the general rule that only a licensed aircraft maintenance engineer may certify maintenance. It reduces the cost and scheduling burden for operators because the PIC can perform the inspection without the need to schedule a LAME. However, the PIC’s certification is valid only for that specific visual inspection; it does not extend to the repairs or to the installation prohibition. The PIC also has the right (or duty in practical terms) to carry a copy of the ASB and the directive in the aircraft if the PIC option is used. The operator has the right to use the PIC option, but that is not mandatory; they may instead use a LAME.

The directive also implies a duty on the holder of the type certificate (Eurocopter) to keep the ASB and repair sheets available and updated. Operators have a right to receive those documents from Eurocopter or from CASA. The note referencing EASA AD 2009-0039 creates a duty on operators to be aware of any changes in that EASA AD, because the directive says “or later EASA approved revision” for the ASB. If EASA approves a later revision, the operator must comply with it, even if CASA has not separately issued an amendment. That creates a dynamic duty that requires operators to monitor EASA’s website or other sources for changes.

Failure to comply with an airworthiness directive issued under the Civil Aviation Act 1988 is not a minor administrative matter. The Civil Aviation Act, section 20(1), makes it an offence to operate an aircraft that does not comply with a direction given by CASA, including an airworthiness directive. The maximum penalty for an individual is 50 penalty units (at the time of issuance, one penalty unit was $110, so $5,500). For a body corporate, the penalty is 5 times that amount: 250 penalty units ($27,500). In addition, operating a non-compliant aircraft may result in the suspension or cancellation of the air operator’s certificate or the aircraft’s certificate of airworthiness. CASA can also issue a notice of proposed suspension (NOPS) or take immediate enforcement action under section 20AA if the non-compliance poses a serious risk to air safety. The directive itself does not specify penalties, but it is a legal instrument under the Act, so the penalty provisions of the Act apply.

The plaintiff (the regulator) must prove that the operator or person knew or ought to have known that the helicopter was non-compliant. However, under the Act, many provisions are strict liability in practice. If an operator fails to perform the visual inspection at the ALF check, that is a breach. If a PIC performs the inspection without having been properly trained, that is also a breach. If a maintenance organisation installs a blade without ensuring it has been inspected and repaired per the ASB, that organisation faces penalties.

Beyond criminal penalties, CASA can take administrative enforcement: it can issue a direction to ground the aircraft, impound the maintenance release, or refuse to issue a certificate of airworthiness renewal. Insurance policies often exclude cover if the aircraft is operated in breach of an airworthiness directive. In the event of an accident, the Civil Aviation Safety Regulations may allow the Australian Transport Safety Bureau (ATSB) to find that non-compliance with an AD was a contributing factor. That can expose the operator to civil liability under common law negligence or under the Civil Aviation (Carriers’ Liability) Act.

The directive also requires the AD to be entered on the Maintenance Release. False or misleading entries on a maintenance release are offences under regulation 42 of the Civil Aviation Regulations, with penalties similar to those for operating a non-compliant aircraft.

No specific enforcement history is provided in the source document. But given the potential for catastrophic failure (tail rotor gearbox separation), CASA is likely to treat non-compliance with this directive very seriously.

This airworthiness directive sits within the framework of the Civil Aviation Act 1988 and the Civil Aviation Regulations 1988 (CAR) and the Civil Aviation Safety Regulations 1998 (CASR). It is a direction issued under the authority of the Act. It supplements and overrides any conflicting provisions in the regulations or in the approved maintenance program for the aircraft. For example, if the approved maintenance program for an AS 355 calls for a tail rotor blade inspection only at intervals of 50 flight hours, this AD overrides that and mandates a 10 flight hour interval. The AD also interacts with the requirement for a “Maintenance Release” under CAR 42 and CASR Part 42. The directive must be entered on the release, and that entry becomes a mandatory maintenance requirement. Failure to have that entry may cause the aircraft to be unairworthy.

The directive references the Eurocopter Alert Service Bulletin and repair sheets. Those documents are not themselves law but are incorporated by reference. If an operator complies with the ASB and repairs, they are deemed to comply with the AD. The directive also references EASA AD 2009-0039. That is a foreign airworthiness directive that has no direct legal force in Australia, but by referencing it, the Australian AD creates a requirement to comply with it (or later revisions) as a standard. Operators must therefore be aware of EASA requirements as well as CASA’s.

The directive also interacts with the provisions of the Civil Aviation Act regarding “airworthiness”. Section 20 of the Act gives CASA the power to issue directions to ensure airworthiness. This AD is such a direction. If CASA later determines that the repair sheets are insufficient or that a different inspection method is needed, it could issue a new AD to replace or amend this one.

The interaction with the contractual framework is important. Leases, sale agreements, and loan covenants often require the aircraft to be maintained in accordance with all applicable ADs. Failure to comply with this AD could put the operator in default under those commercial contracts. The AD does not override contractual obligations; it adds to them.

Finally, the AD interacts with the Australian Transport Safety Bureau (ATSB) investigations. If an accident occurs involving tail rotor blade failure, the ATSB will examine compliance with this AD and may recommend prosecution or further regulatory action. The AD also interacts with international airworthiness frameworks. Australia is a signatory to the ICAO Chicago Convention, and ICAO Annex 8 requires each State to ensure that aircraft on its register comply with continuing airworthiness requirements. This AD is part of Australia’s compliance with that obligation.

Amendment 5 is the fifth revision of AD/AS 355/60. The source document provides background on the earlier amendments. The original AD was issued by the French civil aviation authority (DGAC) in response to a report of separation of a tail rotor blade trailing edge section. Amendment 1 introduced actions specific to blades installed on version N helicopters that are fitted with a 30mm trailing edge tab. Amendment 2 introduced requirements aimed at alleviating maintenance for tail rotor blades repaired as per Repair Sheet FR CN 376, as specified in the latest revision of the requirement document (the ASB). Amendment 3 added a new Repair Sheet (FR CN 453) and extended the repair accomplishment timescale accordingly, as specified in the requirement document. Amendment 4 introduced a correction to the compliance time for Requirement 1, but with no change to the technical requirements. Amendment 5 is the current version, issued in response to a new EASA AD which adds the Model AS 355 NP helicopter to the applicability. The technical requirements remain unchanged from Amendment 4; only the list of affected models was expanded. The source states that at the time this directive was issued, no AS 355 NP helicopters were on the Australian Register. That means the change was prospective: it brought the NP model within the scope so that if any NP is imported or registered, it must comply immediately. The amendment became effective on 4 June 2009. The compliance times for earlier amendments remain unchanged by this amendment - that is, the repetitive inspection interval (ALF check or 10 flight hours) and the one-off repair deadline (31 March 2009) continue to apply. The note that “compliance times remain unchanged” also means that if an operator had not yet complied with a requirement from an earlier amendment, they were still in breach even after Amendment 5. The amendment process appears to be managed by CASA, with the delegate David Villiers signing the directive on 17 April 2009.

There is no mention of any litigation in the source document. Airworthiness directives of this type (mandatory continuing airworthiness) rarely generate reported litigation in Australia, because they are technical and administrative. Challenges to an AD would be limited to judicial review in the Federal Court under the Administrative Decisions (Judicial Review) Act 1977 or under the common law. Grounds might include unreasonableness, procedural error, or jurisdictional error. However, CASA’s power to issue ADs under the Civil Aviation Act is broad and discretionary. The courts typically defer to CASA’s technical expertise. No known case arises from this specific AD. The source is itself a regulatory instrument; it does not discuss any prior court decisions. It is possible that a dispute could arise over the interpretation of the requirement, e.g. what constitutes “trained to do the inspection by an appropriately qualified person”, but no such dispute appears in the public record. The directive also applies only to a limited fleet of helicopters (AS 355s, which are not extremely numerous in Australia), so the likelihood of litigation is low. Operators who are aggrieved by the cost or inconvenience of compliance might complain to the Commonwealth Ombudsman or the Parliamentary committee on delegated legislation, but that would not be litigation. In short, the litigation history is effectively nil, and the directive has been in force since 2009 without apparent challenge.

Several aspects of this directive may catch operators unaware. First, the inspection is required at each ALF check, defined as the check after the last flight of the day. If a helicopter flies multiple flights in a day, the inspection must be done after the final one. But the directive also says “thereafter at intervals not exceeding 10 flight hours between two successive checks.” That means if the helicopter does not fly for several days, the 10 flight hour clock still runs from the last inspection. It does not reset after a period of no flight. So if the aircraft is parked for a month, the 10 flight hour limit has already passed and the operator must perform the inspection before the next flight, even if the aircraft has not moved. Second, the directive says “No person shall install tail rotor blades … unless they have been inspected and repaired, as necessary, in accordance with paragraph 2.B.1 of ASB No. 05.00.38 Revision 3, or later EASA approved revision.” That is a prohibition on installation, not a requirement that blades be inspected before each flight. If an operator has a blade stored in stock that has never been inspected under this AD, they cannot install it on a helicopter. This imposes a record-keeping obligation: all blades in inventory with the listed part numbers must have documentation showing they have been inspected and, if required, repaired. Third, the PIC inspection option is limited. The PIC must be trained by an “appropriately qualified person” - the directive does not define who that is. CASA guidance would likely accept a person with a LAME rating or a training organisation approved by CASA or Eurocopter. But if the PIC purports to self-train, that may not be sufficient. The burden of proving the training is adequate falls on the operator if audited. Fourth, the requirement to carry copies of the ASB and the directive in the aircraft when the PIC option is used is often overlooked. Failure to carry those documents could be a separate breach of the AD. Fifth, the directive states “This Directive shall be entered on the Maintenance Release as maintenance required.” If the AD is not entered, the aircraft may be deemed unairworthy even if the physical inspection has been done. Sixth, the directive references “later EASA approved revision” of the ASB. If EASA approves a Revision 4 that modifies the inspection method or repair criteria, the operator must comply with that revision immediately, even if CASA has not reissued the AD or published a new one. That means operators must monitor EASA’s website for changes applicable to the Eurocopter ASB. Seventh, compliance time for requirement 2 was “No later than 31 March 2009”. If an operator acquired a helicopter after that date with a blade that had not been repaired under FR CN 376 or 453, that operator is now non-compliant and must accomplish the repair before flight. The AD does not provide a grace period for new operators. Eighth, the directive does not allow for any alternative means of compliance without prior CASA approval. Operators who wish to use a different inspection method or interval must apply to CASA for an alternative means of compliance (AMOC) under the Civil Aviation Regulations, which can be a lengthy process. Ninth, the directive applies to specific serial numbers for certain part numbers. The requirement 2 language is complex: it applies to blades with part number 355A12-0050-00, -01, -02, -03, -04, -05 with serial numbers listed in ASB 05.00.38 Revision 3, or later EASA approved revision, and on blades with serial numbers below 8419 for which the annotation “repaired as per Work Card 64.10.00.872” or “repaired as per Work Card 64.10.20.712” is recorded on the log card. That means not all 0050 series blades need the repair; only those in the ASB list or below 8419 with those specific annotations. However, the inspection requirement (requirement 1) applies to all blades with listed part numbers regardless. So an operator must first determine if their specific blade needs repair, and then ensure it has been done.

Compliance with AD/AS 355/60 Amdt 5 requires the operator to take the following steps, in order:

1. Determine if the helicopter is within the applicability. The directive applies to AS 355 models E, F, F1, F2, N and NP. Check the aircraft type certificate data sheet to confirm the model. Also verify that the tail rotor blades installed or in inventory have part numbers listed in the applicability: 355A12-0031-01 through -14, 355A12-0040-00 through -08, 355A12-0050-00 through -05. If the blades have different part numbers, the directive does not apply to that aircraft, but note that the AD may still apply to blades stored for later installation.

2. Obtain a copy of Eurocopter Alert Service Bulletin No. 05.00.38, Revision 2 (or later EASA approved revision). Also obtain Revision 3 (or later) for the repair requirements. These can be obtained from Airbus Helicopters (formerly Eurocopter) or from the CASA website if published there. Also obtain the Repair Sheets FR CN 376 and FR CN 453, which are included in the ASB or available separately.

3. Perform the initial visual inspection of all affected tail rotor blades following the instructions in paragraph 2.B.1 of the ASB. Even if the aircraft has not flown since the AD became effective, the initial inspection must be done before further flight. The inspection may be performed by a Pilot in Command who has been trained by an appropriately qualified person, or by a licensed aircraft maintenance engineer (LAME). If using a PIC, ensure that the PIC has documentation of their training (e.g. a training record from a LAME or maintenance training course).

4. If a crack is found during the inspection, do not fly the helicopter. Accomplish the instructions in paragraph 2.B.2 of the ASB. That typically involves replacing the blade or performing a repair in accordance with the repair sheets. Only a LAME or an approved maintenance organisation may perform the repair. The PIC cannot certify a repair.

5. For blades with part number 355A12-0050-00 and its dash variants, check the serial number. If the serial number is listed in ASB 05.00.38 Revision 3 (or later), or if the serial number is below 8419 and the log card shows the annotation “repaired as per Work Card 64.10.00.872” or “repaired as per Work Card 64.10.20.712”, then the operator must accomplish the instructions of Repair Sheet FR CN 376 or FR CN 453. This is a one-time repair that should have been completed by 31 March 2009. If it was not done, it must be done now. If the blade has already been repaired under those repair sheets and the repair is documented, no further action is needed.

6. For any new or used blade that is to be installed on the helicopter (including replacement blades), ensure that the blade has been inspected and, if necessary, repaired in accordance with paragraph 2.B.1 of the ASB (Revision 3 or later). Do not install any blade with a listed part number unless you have written evidence (e.g. a maintenance release or log card entry) showing that it has been inspected and any required repair accomplished. This applies even if the blade comes from stock or from another aircraft.

7. Enter the AD on the Maintenance Release for the aircraft. The entry should state that AD/AS 355/60 Amdt 5 applies and that the required inspections and repairs have been completed. For ongoing compliance, note the repetitive inspection interval. The Maintenance Release must be updated each time a repetitive inspection is performed.

8. If the PIC performs the visual inspection, ensure that a copy of the ASB (the requirement document) and a copy of this directive are carried in the aircraft at all times. The pilot must also record the inspection in the aircraft log or the Maintenance Release, and sign it off.

9. Establish a system to track the repetitive inspections. The inspection is due at each check after the last flight of the day (ALF check). In practice, this means that after each flying day, the pilot or engineer must inspect the tail rotor blades. However, the directive also says “thereafter at intervals not exceeding 10 flight hours between two successive checks.” If the aircraft flies only one flight of less than 10 hours, the ALF check covers it. If the aircraft flies multiple flights totalling more than 10 hours without an ALF check, the 10 hour limit must not be exceeded. So the operator must also log flight hours and ensure that a check is performed before the 10 hour point is reached. This can be done by having the pilot perform the check at the end of each day, which will always be within 10 hours unless the aircraft flies more than 10 flight hours in a single day (unlikely for a helicopter but possible). If the aircraft is in a remote location and the pilot is not trained, the operator must ensure a trained person (PIC or LAME) is available.

10. Maintain records of all inspections and repairs. The records must be kept for the life of the blade or aircraft, as per CAR 42 and CASR Part 42. If the aircraft is sold or leased, provide the records to the new owner or operator.

11. Monitor EASA for any later revisions of ASB 05.00.38. If a new revision is approved by EASA, check whether the inspection method or repair requirements change. If they do, you must comply with the new revision even though the CASA AD has not been updated. This may require obtaining the new revision and revising your procedures.

12. If you believe there is an alternative means of compliance that provides an equivalent level of safety, you may apply to CASA for an AMOC. That application must be made in writing, and you must demonstrate that the alternative is at least as effective as the prescribed inspection and repair. Without an approved AMOC, you must use the exact methods in the ASB.

By following these steps, the operator can achieve and maintain compliance, avoid penalties, and ensure the airworthiness of the helicopter. Non-compliance is not an option given the potential for catastrophic failure and the legal consequences.