AD/ATR 42/24 - Flaps - 45 Degree Configuration

The primary operational concept is the “45‑degree flaps configuration”. On the ATR 42, deploying flaps to 45 degrees provides a steeper approach path and lower landing speed, potentially beneficial at short runways. However, the AD arises from a risk identified in the background: a tailplane stall caused by ice accretion on the tail surface combined with flaps at 45 degrees and approach‑speed flying. That condition can produce an uncontrollable nose pitch‑down at low altitude. The AD therefore defines two distinct states of flaps use: “normal operations” (max 30 degrees) and “emergency operations” (45 degrees permitted only by captain’s decision under strict conditions). The AFM Temporary Revision No. 51 is the central document that redefines the limitations and performance sections of the EASA‑approved AFM. It does not itself grant airworthiness approval for routine 45‑degree use; as Note 2 clarifies, the new Appendix 20 “Landing with Flaps 45°” is “only ATR guidance and recommended information” and can be used only if a national aviation authority separately grants an operational exemption. That subtlety means the AD does not eliminate the possibility of exemption entirely, but it raises the bar: the exemption is now a matter for each national authority, and the AFM provides guidance rather than approval. The mechanical concepts include the “red colour mechanical stop” installed on the flaps control lever, which physically prevents selecting 45 degrees during normal operations. This stop is tied to the speed‑limits placard, which lists VFE (flaps extended speed) limitations. The placard must state the emergency speed limit for the 45‑degree setting as 130 knots. The AD relies on several ATR service bulletins: SB ATR42‑27‑0008 (the original restriction and mechanical stop installation), SB ATR42‑27‑0080 (the now‑prohibited exemption modification), and SB ATR42‑27‑0099 (a later bulletin for specific aircraft). The concept of “manufacturing serial number” (MSN) determines applicability for certain requirements. Four MSNs (027, 102, 106, 214) are singled out because they had previously been modified per the exemption bulletin and must now be reversed. Two other MSNs (097, 403) require direct modification per SB ATR42‑27‑0099 regardless of prior status. The AD also introduces the concept of “icing conditions” as a trigger for the emergency use prohibition: even in an emergency, the 45‑degree flaps setting cannot be used if the aircraft has encountered icing during the flight or is not clear of ice. This introduces an operational judgment call for the captain. Another key concept is the supersession of the previous regulatory regime. The DGAC AD F‑1986‑130‑003, which had allowed exemptions, is now no longer applicable. The AD notes that old directive is listed in Table 1 of AD/ATR 42/1, and operators must determine applicability of each AD in that table; but because F‑1986‑130‑003 is superseded, it should be considered inoperative. Finally, the compliance concept distinguishes between short‑term (7 days for the AFM revision) and medium‑term (6 months for physical modifications). This staggered approach acknowledges the practical need to update flight manuals quickly while allowing time for hangar work.

The primary duty‑holders are operators and owners of ATR 42‑200, 42‑300, and 42‑320 aircraft registered in Australia or operated under Australian‑issued certificates. Because the AD is issued by CASA, it applies to any aircraft within CASA’s regulatory jurisdiction, including those operated by Australian air operators and those registered in Australia but operated overseas. The AD also indirectly affects maintenance organisations that perform the required modifications, since they must possess the relevant EASA‑approved service bulletins and have the capability to install mechanical stops and update placards. Flight crew are directly affected: the revised AFM imposes new restrictions on flap usage, and the emergency‑use provision requires the captain to assess whether icing conditions have been encountered and whether the aircraft is clear of ice before selecting 45 degrees in an emergency. This changes cockpit procedures and decision‑making. The AD most heavily affects operators who had previously obtained an operational exemption from their national aviation authority to use flaps 45 degrees at specific airfields. Such operators must now reverse that configuration: they must undo the modification that removed the mechanical stop and install the restriction. This is costly and may affect operational flexibility at short runways. The AD specifically identifies aircraft with manufacturing serial numbers 027, 102, 106, and 214 as having been modified per SB ATR42‑27‑0080; those operators have a direct requirement to undo that modification. Also affected are operators of MSN 097 (if not previously modified per SB ATR42‑27‑0008) and MSN 403, both of which must modify per SB ATR42‑27‑0099. Operators of aircraft that already have the mechanical stop and correct placards are not required to take further action beyond verifying compliance and ensuring Mod 01314 is not installed. The AD affects ATR as a manufacturer: operators are directed to send accomplishment reports back to ATR after embodying the required service bulletins, and to contact ATR for procedures if discrepancies are found. This imposes an administrative obligation on ATR to respond and provide corrective instructions. The AD also indirectly affects national aviation authorities other than CASA. Because Note 2 contemplates that an NAA could still grant an operational exemption for using the 45‑degree flaps setting, the AD creates a tension: the aircraft’s AFM now states that such use is only for emergencies, but an NAA exemption could allow it for normal operations at specific airfields. This may lead to inconsistent regulatory outcomes across jurisdictions, especially for Australian‑registered aircraft operating overseas under bilateral agreements. Finally, CASA itself is affected as the issuing authority, responsible for monitoring compliance, potentially auditing maintenance records, and taking enforcement action for non‑compliance. The AD was signed by a delegate of CASA, so CASA is the enforcing body.

The AD imposes several mandatory duties on operators and owners. The most time‑critical duty is to revise the AFM by incorporating Temporary Revision No. 51 within 7 days of the effective date (16 July 2008). This is a duty to update documents, and it applies to all aircraft, regardless of whether they already have the mechanical stop. The second duty is to physically modify the aircraft within 6 months to restrict flaps to a maximum of 30 degrees in normal operations. This duty is differentiated by aircraft configuration and serial number. For aircraft that have not embodied Mod 01192 or SB ATR42‑27‑0008, the duty is to install the mechanical stop and new placards per the latest revision of that service bulletin. For aircraft with MSN 027, 102, 106, and 214 that were modified per SB ATR42‑27‑0080, the duty is to undo that modification and install the restriction per SB ATR42‑27‑0099. For MSN 097 (if not previously modified per SB ATR42‑27‑0008) and MSN 403, the duty is to modify per SB ATR42‑27‑0099. For all other aircraft, the duty is to check that the mechanical stop is installed and the placard reads correctly; if not, the operator must contact ATR to restore the approved configuration. A further duty is to refrain from installing Mod 01314 or implementing SB ATR42‑27‑0080 on any aeroplane. This is a continuing prohibition. Operators also have a duty to send accomplishment reports back to ATR after embodying the service bulletins. There is no explicit duty to file reports with CASA, but the AD itself is a CASA directive, so CASA may require proof of compliance during audits. In terms of rights, the AD does not create new rights but confirms a limited right for the captain to use the 45‑degree flaps configuration in an emergency, subject to two conditions: that icing conditions have not been encountered during the flight and that the aircraft is clear of ice. This is a qualified operational right. The AD also preserves a theoretical right for an operator to seek an operational exemption from a national aviation authority for using flaps 45 degrees at specific airfields, as indicated in Note 2. However, this right is severely constrained: the AFM itself does not approve such use, and the Appendix 20 is only “guidance”. The exemption would need to be granted separately, and the operator would then have a non‑standard AFM configuration. The AD does not provide any right to delay compliance or to seek reimbursement for modification costs. Notably, the AD does not include a provision for alternative means of compliance (AMOC) or a procedure to request an extension. This lack of flexibility imposes a strict duty: if an operator cannot comply within 6 months, the aircraft may become unairworthy. The only explicit avenue for resolving discrepancies is to contact ATR, not CASA, for the restoration procedure.

The AD itself does not specify penalties; it is a directive issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998 (CASR). Breach of an airworthiness directive is a serious regulatory offence. Under the Civil Aviation Act, operating an aircraft that does not conform to an applicable AD may result in civil penalty provisions, often with maximum penalties in penalty units (currently $313 per unit for individuals and higher for bodies corporate). For example, CASR 42.525 (if applicable to this vintage aircraft) makes it an offence to operate an aircraft unless the AD has been complied with. More broadly, operating a non‑compliant aircraft is likely a contravention of the airworthiness requirements under Part 4A of the Act, exposing the operator to enforcement action that may include infringement notices, enforceable undertakings, or court‑imposed penalties. CASA can also suspend or cancel an air operator’s certificate or an aircraft’s certificate of airworthiness if the AD is not complied with. The AD is signed by James Coyne as a delegate of CASA, which indicates CASA’s formal adoption of the directive. Enforcement is typically reactive: CASA conducts routine surveillance of maintenance records and may inspect aircraft for placard and mechanical stop compliance. Given the AD’s age (2008), most operators likely have complied, but for any aircraft still found non‑compliant, CASA could issue a direction to ground the aircraft until compliance is achieved. The practical risk for an operator is that a non‑compliant aircraft could be denied insurance coverage or found to be unairworthy in a post‑accident investigation, leading to liability for damages. The AD does not create any private right of action, so passengers or third parties cannot sue directly for breach of the AD. However, breach of an AD is likely to be evidence of negligence in a civil tort claim for personal injury or property damage. The AD’s background references a training‑flight incident involving pitch control loss; that factual background may be used in litigation to establish foreseeability of harm. The AD’s prohibition on installing Mod 01314 also means that any person who does so knowingly may be facing penalties for contravening a direction. There is no provision for criminal penalties in the AD text, but the underlying Act provides for up to 5 years imprisonment for reckless conduct that endangers the safety of an aircraft. In practice, enforcement for this specific AD is likely to be administrative rather than criminal, unless there is evidence of deliberate non‑compliance that led to an accident.

This AD operates as a specific, mandatory requirement under the Australian regulatory framework for airworthiness. It sits beneath the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998. It is issued by a delegate of CASA, and compliance is a condition of holding a certificate of airworthiness for the affected aircraft. The AD explicitly supersedes DGAC France AD F‑1986‑130‑003, which had previously applied to these aircraft. That earlier French AD was listed in Table 1 of AD/ATR 42/1, which is a general directive requiring operators to determine the applicability of each listed foreign AD. Because this Australian AD now directly mandates the same subject matter, the old French AD is no longer applicable for Australian‑registered aircraft. However, AD/ATR 42/1 itself remains in effect for other listed directives. Operators must still comply with all other applicable ADs on that list, except where superseded. The AD also references EASA AD 2008‑0124, noting that this Australian AD “refers” to that European directive but does not adopt it wholesale. The EASA AD is the originating safety action; CASA has essentially mirrored it for Australian jurisdiction. This means operators who have already complied with the EASA AD may have already met the Australian requirements, provided the service bulletin revisions and deadlines align. However, the Australian AD has its own effective date and compliance times, so operators must ensure they meet the Australian deadlines, not the EASA ones. The AD interacts with the broader network of continued airworthiness directives for the ATR 42. For example, AD/ATR 42/1 requires operators to maintain a register of applicable ADs. This AD must be added to that register and tracked for compliance. The AD also interacts with the operator’s maintenance program under CASR Part 42 or 145. The physical modifications (mechanical stop installation, placard replacement) are likely to be categorised as modifications requiring approval from CASA or a delegated maintenance organisation. Because the AD mandates specific service bulletins, the work can be performed by a Part 145 approved maintenance organisation using the instructions in those bulletins. The AD also interacts with flight operations rules. The AFM revision must be incorporated into the operator’s flight manual and must be carried on board. The restriction on flap usage may affect landing performance calculations and required runway lengths, which are part of the operator’s operations manual under CASR Part 121 or 135. Operators who previously relied on the 45‑degree flaps at short runways must now reassess their network and may need to add new restrictions or even discontinue operations to certain airfields. This AD does not explicitly override any state or territory laws, but it is a federal instrument that prevails in matters of aviation safety. It does not create any interaction with consumer law or competition law, though the cost of compliance may affect smaller operators disproportionately, which is a competitive issue. Finally, the AD interacts with international obligations: Australia is a signatory to the Chicago Convention, and CASA’s adoption of ADs harmonises with EASA standards, facilitating cross‑border recognition of airworthiness.

The AD itself is a single, final directive with an effective date of 16 July 2008. There is no indication in the source text that this version has been amended since issuance. However, the AD supersedes an earlier French AD, DGAC F‑1986‑130‑003, which had been revised at least once (Revision 1 in April 1997). That earlier AD had a long history: originally issued after the training flight incident, it initially prohibited use of flaps at 45 degrees except in emergency, and then mandated installation of a mechanical stop via Mod 01192. Later, the DGAC allowed operational exemptions via Mod 01314. The current AD effectively reverses that exemption allowance. The Australian AD itself may have been preceded by earlier editions of AD/ATR 42/24? The source does not show any revision number or previous version. It is simply labelled “AD/ATR 42/24” and “9/2008 DM”. The “DM” likely stands for “Directive Modification” or similar internal code. There is no indication that this AD has been reissued or amended since 2008. Given its age, it is possible that CASA or EASA have issued superseding directives, but the user provided only this text. Therefore, for the purposes of this analysis, the amendment history is limited: the AD replaced the earlier French AD regime and established the current restriction. Operators should verify whether a more recent AD for the same subject exists, such as an EASA AD that may have been updated or a later CASA AD that supersedes this one. However, based solely on the source, there is no amendment history within the AD itself. The AD does include a note that EASA AD 2008‑0124 supersedes the DGAC AD, but that is a separate instrument. The Australian AD’s own amendment history is not documented in the text. Typically, CASA ADs are published in the Federal Register of Legislation and may be amended by a subsequent AD or by a CASA instrument. A search beyond this source would be needed to determine if AD/ATR 42/24 has been varied. The source indicates a single signing date (10 July 2008) and effective date (16 July 2008), with no subsequent dates. So the analysis here must assume that this is the operative version as provided. For a practising lawyer or compliance professional, checking whether this AD has been replaced or amended is a critical step, but it cannot be answered from this source alone.

The source text does not refer to any litigation concerning this AD, nor does it reference any court cases. There are no case names, court decisions, or tribunal reviews mentioned. Given the AD’s specific technical nature and issuance date of 2008, it is unlikely to have generated significant public litigation. Airworthiness directives are generally challenged rarely, and when they are, the challenge would typically be an application to the Administrative Appeals Tribunal (AAT) for review of CASA’s decision, or a judicial review in the Federal Court. The threshold for review is limited: CASA must have made a mistake of law, or the decision must be unreasonable. In the context of a safety directive, courts give significant deference to the regulator’s assessment of risk. No AAT decisions or Federal Court rulings citing this specific AD are publicly known. The background incident (a training flight causing pitch control loss) may have been the subject of an internal investigation or a confidential report, but it is not a litigation. The AD itself is a preventive measure, not a response to a lawsuit. However, the AD could be relevant in later civil litigation if an accident occurs involving a non‑compliant aircraft. In such a case, the plaintiff might argue that breach of the AD was negligence per se. But that would be a future use, not a history. The AD has also not been the subject of any coronial inquest or public inquiry, as far as is publicly known. It is also possible that the AD was adopted without controversy, given that it merely reinstates restrictions that were in place before the exemption route was created. The only potential source of litigation would be an operator whose aircraft was grounded due to non‑compliance, but no such case has surfaced. Therefore, the litigation history for this specific AD is effectively nil. This is typical for a narrow, technical airworthiness directive. Practitioners should note that the lack of litigation does not imply the AD is legally insignificant; it merely means that compliance has been straightforward enough that no disputes have reached the courts.

Several subtle but important points in the AD can catch out an unwary operator or maintenance organisation. First, Note 2 states that the new Appendix 20 in AFM TR No. 51 “does NOT constitute any airworthiness approval to conduct Normal Operations with Flaps at 45°”. The appendix is only guidance for use in case an individual NAA exemption is granted. This means an operator cannot simply rely on the appendix as a basis for routine use, even if the captain decides it is safe. The exemption must come from the operator’s national aviation authority, and even then, the AFM does not sanction it. This creates a potential regulatory gap: an operator might obtain an exemption but still be in violation of the AFM limitation unless the exemption explicitly overrides the AFM. The AD effectively forces any 45‑degree use (outside emergency) to be an exceptional, non‑standard operation. Second, Requirement 7 prohibits the future installation of Mod 01314 or SB ATR42‑27‑0080. That is a permanent prohibition. However, the AD does not explicitly require the removal of Mod 01314 from aircraft that already have it; instead, Requirements 3 and 4 for specific MSNs require undoing the modification. For other aircraft with Mod 01314 but not in the listed MSNs, the AD is silent. Requirement 6 covers “all other ATR 42 not addressed by Requirements 2, 3, 4 & 5”. That requirement is to check that the red mechanical stop is installed and the placard states the emergency speed. If an aircraft has Mod 01314 (which removed the mechanical stop), it would not have the red stop, so a discrepancy would be found, requiring the operator to contact ATR for a restoration procedure. So the AD does indirectly mandate removal of Mod 01314 from all aircraft, but only through the check procedure. An operator might mistakenly think that if their aircraft is not one of the specific MSNs, they can keep Mod 01314 as long as they file for an exemption. That is wrong. Third, the compliance deadline for Requirement 1 (AFM revision) is only 7 days, which is very tight. Operators must obtain TR No. 51 and physically insert it into each AFM within a week. Failure to do so renders the aircraft non‑compliant even if the physical modification is still in the 6‑month window. Fourth, the AD does not specify what happens if the required service bulletin is not yet available in the operator’s language or if the operator cannot source the parts within 6 months. There is no explicit alternative means of compliance. This could ground an aircraft. Fifth, for aircraft with MSN 027, 102, 106, and 214, the AD requires “undoing changes introduced by SB ATR42‑27‑0080”. That bulletin had allowed the removal of the mechanical stop. Reversing it likely requires re‑installing the stop and possibly replacing parts. This may be more complicated than a straightforward modification. Sixth, Note 4 clarifies that DGAC AD F‑1986‑130‑003 is no longer applicable, but AD/ATR 42/1 still requires operators to determine applicability of each AD in Table 1. An operator might fail to mark that old AD as superseded, leading to confusion or duplication of effort. Seventh, the AD refers to “EASA approved revision” for the service bulletins. If an operator uses a revision that is not EASA‑approved (e.g., an earlier revision approved only by DGAC), that might not satisfy the requirement. Eighth, the AD requires sending accomplishment reports to ATR. If the operator fails to do so, the modification is still effective, but the manufacturer may not update its records, which could cause issues with future ADs or resale. Finally, the AD was issued in 2008 and may now be superseded by later ADs. Relying solely on this text without checking for updates could lead to non‑compliance with current requirements.

Compliance requires a phased approach. The first action must occur within 7 days of the effective date (16 July 2008): each affected aircraft’s AFM must have Temporary Revision No. 51 inserted. The operator must obtain TR No. 51 from ATR (or from CASA or the applicable source). The revision changes the limitations and performance sections to restrict 45‑degree flaps to emergency use only under specified conditions. The operator should also delete pages concerning Mod 01314 if they exist. The TR must remain in the AFM until a normal EASA‑approved AFM revision contains identical information; at that point, the normal revision may replace the TR. Within the same 7‑day window, the operator should also ensure that the flight crew is briefed on the new limitations and the emergency‑use conditions. The second set of actions must be completed within 6 months. The operator must first identify the specific aircraft configuration by manufacturing serial number and modification status. For aircraft that have not embodied Mod 01192 or SB ATR42‑27‑0008 at any revision: obtain SB ATR42‑27‑0008 Revision 6 (or later EASA‑approved revision) and follow its accomplishment instructions to install the red mechanical stop on the flaps control and affix new speed‑limits placards. After embodiment, send the accomplishment report to ATR. For aircraft with MSN 027, 102, 106, and 214 that were modified per SB ATR42‑27‑0080: obtain SB ATR42‑27‑0099 original issue or later EASA‑approved revision. Follow its instructions to undo the earlier modification, restrict flaps to 30 degrees, and install new placards. Send the report to ATR. For aircraft MSN 097 (if not previously modified per SB ATR42‑27‑0008) and MSN 403: modify per SB ATR42‑27‑0099 directly. For all other aircraft not covered by the above: inspect the flaps control to verify that the red mechanical stop is installed. Check the speed‑limits placard to confirm it reads: “EMER: (45°). 130 kt”. If any discrepancy is found, contact ATR to obtain the procedure to restore the aircraft to the approved configuration. Do not install Mod 01314 or implement SB ATR42‑27‑0080 on any aircraft. The operator should also update its AD compliance register to reflect the completion of these actions, and mark DGAC AD F‑1986‑130‑003 as superseded. The maintenance organisation performing the work should hold the appropriate EASA or CASA approvals for the modifications. All work must be recorded in the aircraft maintenance log. The operator should also review its operations manual to ensure that any reference to the previous 45‑degree flaps exemption is removed or updated to reflect the new limitation. For any future emergency use of 45 degrees, the operator must ensure that pilots are trained on the conditions: no in‑flight icing encountered and aircraft clear of ice. Finally, the operator should periodically verify that no subsequent AD has superseded or modified the requirements, especially given the age of this directive.