AD/CONVAIR/27 - Drag Strut Shearbolt

The directive introduces and relies on several distinct concepts that govern its application. The first is the classification of drag struts into three categories: non modified struts, modified struts, and new struts. A non modified strut is the original configuration that has never been altered by Service Engineering Reports 15-4-340-38/440-38 or 15-4-340-44A/440-44A, nor by Part III of Service Bulletin No. 32-8. A modified strut is one that has received any of those earlier modifications but has not yet been reworked per Part IV of the same bulletin. A new strut is defined as a specific part number, 340-7310231-1, that has also not been reworked per Part IV. This categorisation is critical because each type has a different initial compliance threshold. Non modified struts must be inspected within 1200 landings of the effective date (unless already done in the last 4800 landings), whereas modified and new struts have a later initial inspection point tied to 26,000 landings total or 6000 additional landings, whichever is later. The concept of a landing is used as the metric for compliance intervals. A landing is presumably counted each time the aircraft touches down, which means operators must maintain accurate counts of landings, not just flight hours. This is a more granular metric than calendar time and may be more relevant to fatigue cracking in landing gear components. The next key concept is the incorporation by reference of a specific manufacturer's service bulletin: General Dynamics Service Bulletin No. 32-8 (for 340 models, S.B. No. 32-8, dated 10 August 1973) or later FAA approved revisions. The AD does not reproduce the inspection or modification procedures; it simply mandates that those procedures be followed. This means an operator must obtain and comply with the exact content of the bulletin, including any later revisions approved by the FAA. The concept of later FAA approved revisions introduces a floating compliance standard: the requirement can change without a new Australian AD being issued, as long as the FAA approval is documented. The directive also refers to the concept of disassembly inspection, which is more intrusive and costly than an external inspection or a non destructive test. It requires the strut to be removed and taken apart to visually inspect the shear bolt attach hole area. This downtime and labour cost is a necessary consequence of the AD. Another important concept is the terminating action: incorporation of Part IV of the service bulletin. Once a strut has been reworked per Part IV, the repetitive inspection requirements cease (the compliance table for modified/new struts says "until the strut has been modified in accordance with the provisions of Part IV"). This creates an incentive for operators to perform that modification permanently, rather than continuing indefinite repetitive inspections. However, the AD does not mandate Part IV as a one time compliance; it allows the operator to choose to keep inspecting every 6000 landings indefinitely, which may be cheaper for low utilisation aircraft. The concept of landings intervals also includes a grace period on replacement parts: if a used modified strut is installed that does not have Part IV, the initial inspection is due on or before 20,000 landings from replacement, then every 6000. If the replacement part does have Part IV, the initial inspection repeats every 20,000 landings following each rework. This creates a cascading compliance logic that operators must track per component.

This directive directly imposes obligations on any person or entity that operates, owners, or maintains a General Dynamics (Convair) Model 340 or 440 series aeroplane registered in Australia. That includes commercial air transport operators, charter companies, freight carriers, private owners, flying schools, and any organisation that holds an Air Operator's Certificate involving these aircraft. Because the aircraft type is an older, pressurised piston or turboprop aeroplane that saw extensive use in regional and cargo operations, the affected population is likely to be a small but dedicated group of operators with specialised maintenance arrangements. Maintenance organisations approved under Part 145 of the Civil Aviation Safety Regulations are directly affected because they will be required to perform the disassembly inspections, modifications, and replacements. The AD stipulates a specific service bulletin to be used, so the maintenance provider must have access to that bulletin and any FAA approved revisions. This may require purchasing the bulletin from the manufacturer or subscribing to an update service. Parts suppliers and stockists are also indirectly affected: the demand for new or serviceable drag struts (Part Number 340-7310231-1) or repair parts may increase as operators replace cracked struts. The AD does not impose requirements on manufacturers or type certificate holders (General Dynamics is long out of production), but it does rely on the continued availability of service bulletin documentation and spare parts. The compliance burden falls disproportionately on operators with lower utilisation aircraft. Because the initial compliance for modified/new struts is tied to total landings (26,000) or 6000 additional landings, an aircraft that flies infrequently may take many years to reach that threshold, but the AD does not offer a calendar time alternative. This means the AD may require an inspection only after many years of operation, which could reduce the cost impact for low use aircraft. Conversely, high utilisation aircraft will hit the landing thresholds quickly, requiring more frequent inspections. The economic effect on private enterprise includes direct costs of inspection labour, parts if cracks are found, and downtime while the strut is disassembled and reassembled. There is also an opportunity cost if the aircraft is grounded waiting for parts. Small operators with limited cash flow may find the recurring 6000 landing interval burdensome, particularly if they operate multiple aircraft. The AD reduces operator discretion: they cannot choose an alternative inspection method (such as fluorescent penetrant inspection without disassembly, unless the bulletin allows it) because the AD mandates the procedures in the service bulletin. This prescriptive nature can increase compliance costs compared to a performance based directive that would allow equivalent methods. On the other hand, the directive creates a predictable safety baseline that can be factored into operational planning and insurance premiums. The requirement to track landings imposes an administrative burden: the operator must maintain accurate landing counts for each strut, which may not be straightforward if the strut is swapped between aircraft or if landing counting procedures are informal.

The primary duty imposed by this AD is to inspect the left hand upper drag strut of the nose landing gear for cracks at the shearbolt bore, and to take corrective action if cracks are found. This duty falls on the registered operator of the aeroplane, who must ensure compliance under the Civil Aviation Safety Regulations. The operator must first determine the configuration status of each strut: whether it is non modified, modified, or new as defined in the AD. Based on that classification, the operator must schedule and perform the disassembly inspection in accordance with the specified service bulletin. The duty is ongoing: after the initial inspection, the operator must repeat the inspection at intervals not exceeding 6000 landings, unless the strut has been reworked per Part IV of the service bulletin. The AD also imposes a duty to replace a strut if cracks are found; replacement must be with a new or serviceable part of the same type design. The operator has a duty to maintain records of landings and inspections to demonstrate compliance. The directive does not explicitly spell out recordkeeping requirements, but under CASR Part 42, maintenance records must document compliance with airworthiness directives. The operator also has a duty to obtain and follow the latest FAA approved revision of Service Bulletin No. 32-8. This means the operator cannot simply rely on a version from 1973; they must check for any later revisions and comply with those. This creates an active monitoring obligation.

The rights of the operator are limited but include the right to use a later FAA approved revision of the bulletin if it reduces the compliance burden (e.g., by extending intervals or simplifying the inspection). The operator also has the right to install a strut that has been reworked per Part IV, which eliminates the repetitive inspection requirement, effectively buying out of the ongoing duty. The operator may also choose to replace the entire strut with a new or serviceable part, as long as it is the same type design; this might be a one time cost to avoid a complex modification. However, if the replacement part is also not Part IV modified, the repetitive inspection duty transfers to the new part, with its own initial inspection threshold based on landing accumulation. The operator has the right to propose alternative means of compliance (AMOC) to CASA. The AD does not mention AMOC, but the general regulatory framework under CASR 39.023 allows operators to apply to CASA for approval of an alternative method. This right is implicit; if an operator can demonstrate an equivalent level of safety through a different inspection technique (e.g., eddy current without disassembly), they may apply for a variation. The AD also gives the operator a certain grace period: the compliance table includes a provision that for modified/new struts, the initial inspection is due on or before the accumulation of 26,000 landings on a new or modified part, or 6000 additional landings, whichever occurs later. This later of clause gives the operator some flexibility to schedule the inspection.

The source text does not itself specify penalties. However, airworthiness directives in Australia are issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998, specifically Part 39. Non compliance with an applicable AD is a breach of the regulations. Under CASR 39.020, a person must not operate an aircraft unless each applicable AD has been complied with. Operating an aircraft that does not comply is an offence. The maximum penalties for operating a non compliant aircraft can be significant: under the Act, a body corporate may face fines up to 10,000 penalty units for each day of continued operation (currently one penalty unit is $313, so $3.13 million per day maximum). For an individual, the maximum is 2,500 penalty units ($782,500) or imprisonment for up to five years, or both. These are maximums; actual penalties depend on the seriousness. Civil penalties may also apply under the Act. CASA can also take administrative enforcement action: it may suspend or cancel the aircraft's certificate of airworthiness, issue a grounding order, or impose operating restrictions. In practice, CASA will usually issue a notice of proposed suspension or cancellation before resorting to prosecution. For a recurring AD like this one, failure to conduct the repetitive inspection at the required interval could be detected during a ramp check, an annual inspection, or an audit of maintenance records. The AD also has a cascading effect: if cracks develop and go undetected due to non compliance, and the landing gear fails, enforcement could include criminal charges for reckless endangerment if the aircraft was operated in a dangerous manner. However, the AD is narrowly targeted at a specific structural component, so enforcement is likely to be administrative unless there is an accident. The operator is also subject to liability under common law negligence if non compliance leads to injury or damage. The AD does not contain any penalty specific to the directive; it relies on the general penalty regime. Because the AD is mandatory and published in the Australian Airworthiness Bulletin (or register), any maintenance release or annual review of airworthiness must confirm compliance. An operator who falsifies records or misrepresents compliance would face additional penalties for fraud under the Act or general criminal law.

This AD does not exist in isolation. It operates within the framework of the Civil Aviation Safety Regulations, particularly Part 39 (Airworthiness Directives). Under CASR 39.001, an AD is a legislative instrument that must be complied with as a condition of the aircraft's certificate of airworthiness. The AD also interacts with the maintenance rules in Parts 42 and 145. The maintenance provider performing the inspection must be appropriately rated under its Part 145 certificate to perform the type of work (airframe/landing gear). The disassembly inspection may require specific tooling and training. The AD references an FAA AD (73-19-11) and a manufacturer's service bulletin. This incorporates by reference documents that may be subject to copyright and must be acquired. The FAA AD is a US airworthiness directive that was likely adopted by CASA under a bilateral agreement or by direct reference. The interaction with FAA rules means that if the aircraft is also registered in the US or operated under a foreign air carrier permit, compliance with the FAA AD is already mandatory. For Australian operators, the CASA AD may be identical or contain different compliance times; the operator must comply with both if both apply, and the more restrictive normally prevails. The AD also interacts with the Airworthiness Management Exposition required for large aircraft operators. Operators with an approved maintenance system must have procedures to track AD compliance. This AD imposes a landing count based interval, so the operator's flight data recording or logbook procedures must capture landings accurately. For aircraft that are leased or chartered, the operator must ensure that the lessor or charterer is aware of the AD obligation. The AD may also affect the aircraft's eligibility for import or export. If an Australian registered aircraft is sold overseas, the buyer will want proof of AD compliance. There may be interactions with insurance policies: non compliance could void coverage or give the insurer a defence.

The directive does not address state or territory workplace health and safety laws, but the maintenance of landing gear involves manual handling and potential hazards; those laws apply separately. There is also interaction with the Competition and Consumer Act: an operator who fails to comply and continues to charge for flights while operating an unsafe aircraft could face deceptive conduct claims, though this is unlikely for a minor AD. The AD is silent on privacy, human rights, or environmental legislation; none are directly relevant. The directive is an exercise of CASA's power to prescribe airworthiness requirements; it does not grant any enforcement powers to other agencies.

The source provided is the original issue of AD/CONVAIR/27, dated 13 September 2006, effective 26 October 2006. There is no information within the source about any earlier versions of this specific AD, such as a proposal or interim directive. The text references the earlier FAA AD 73-19-11 (Amendment 39-1736) which dates from 1973. The CASA AD appears to be an Australian adoption or recertification of the FAA directive, possibly with some adjustments to compliance times or applicability. The source does not indicate whether AD/CONVAIR/27 supersedes any previous Australian AD on the same subject. It is possible that earlier Australian ADs existed covering the same issue, but the source does not mention them. The inclusion of a background statement and the reference to FAA AD 73-19-11 suggests that the technical requirement originated from the US and was subsequently adopted by Australia through a bilateral process, perhaps as part of standardising ADs under a 2005 bilateral aviation safety agreement. The AD is the third revision of the AD number system: the header shows "AD/CONVAIR/27" with a subnumber "11/2006", indicating it was the 27th Convair series AD and the 11th AD issued in 2006. There is no indication within the document of any subsequent amendments to this AD. In the real world, CASA may have issued later revisions or superseded this AD with a new number, but the source text does not provide that. The user has asked us to only use the source, so we cannot assume any later amendment. The AD itself incorporates by reference later FAA approved revisions to the service bulletin, which is a form of passive amendment: the compliance standard can change without a formal amendment to the AD text. The AD also includes a note that "FAA AD 73-19-11 Amdt 39-1736 refers", which may indicate that the FAA AD itself has been amended over the years. The Australian AD does not list its own amendment history, but we can note that the document appears to be a one off issuance. Practitioners should verify whether any subsequent CASA AD has superseded this directive, given the age of the aircraft type.

The source text contains no reference to any litigation, court cases, or tribunal decisions involving this specific AD. This is consistent with the nature of airworthiness directives: they are typically technical compliance instruments that rarely generate reported litigation. Challenging an AD in court would require an operator to argue that the directive is ultra vires, procedurally invalid, or unreasonable. Given that the AD is based on a manufacturer's service bulletin and an FAA directive, it is unlikely to be successfully challenged on technical grounds. There may have been administrative review applications to the Administrative Appeals Tribunal seeking an extension of compliance times or an alternative means of compliance, but the source does not mention any. The reference to the FAA AD suggests that any US litigation would be separate. It is possible that an accident involving Convair landing gear failure led to the original AD, but the source does not say. The background simply states the intent to detect cracks and prevent failure. Without any litigation history in the source, we cannot speculate. We note that the AD was issued in 2006 and presumably remains in force unless superseded. Over 17 years, there may have been requests for relief or alternative method approvals, but these are unpublished. The AD's design as a repetitive inspection with a terminating action (Part IV modification) suggests that the regulator expected operators to eventually modify the struts and eliminate the ongoing inspection. There is no evidence that any operator sought judicial review. The lack of litigation history does not indicate any acceptance of the AD; it simply means that no disputes reached a reported decision. Practitioners should be aware that compliance is mandatory and that any non compliance could be grounds for enforcement action, which could lead to litigation if contested. The general principle is that airworthiness directives are presumed valid unless set aside by a court, and the cost of challenging them is usually prohibitive relative to the cost of compliance.

There are several easily overlooked features of this AD that could trap an unwary operator. First, the compliance intervals are based on landings, not flight hours or calendar time. An operator who uses flight hours as a proxy for landings (e.g., assuming one landing per hour on a typical flight) may miss the interval if they have short sectors with many landings per hour. The operator must maintain a separate landing count for each strut, including when struts are swapped between aircraft. If an operator does not have a system to count landings, they may inadvertently exceed the 6000 landing repeat interval. Second, the AD incorporates by reference later FAA approved revisions to the service bulletin. This means the operator cannot rely solely on the 1973 version of the bulletin; they must actively monitor for FAA bulletins or other means to determine if the inspection or modification procedures have changed. A later revision might, for example, allow ultrasonic inspection instead of disassembly, or extend the interval. But it could also impose new requirements. Failing to use a later revision could be non compliance. Third, the definitions are critical and may lead to misclassification. A strut that has been modified per Part III of the bulletin is still considered a modified strut and still requires repetitive inspections unless Part IV has been done. A strut that has been repaired (not modified) under Part II is subject to its own regime: inspections every 6000 landings following the repair, with no mention of a later terminating modification. That means a repaired strut may never be free of repetitive inspection unless it is later modified per Part III and then Part IV, adding complexity. Fourth, the AD does not specify what constitutes a "serviceable part" for replacement. If cracks are found, the operator must replace with "new or serviceable parts of the same type design". There is no definition of serviceable; it presumably means a part that itself complies with any applicable ADs and is within its life limits. But an operator who installs a used strut from another aircraft must ensure that strut's landing count and modification status is known and tracked. Fifth, the AD has a clause for new or previously modified struts used for replacement: the initial inspection is due on or before 20,000 landings from time of replacement, or the existing inspection regime? The wording is convoluted and could be misinterpreted. Essentially, if you install a strut that is not Part IV modified, you start a new 20,000 landing count for initial inspection, then repeat every 6000. If you install a Part IV modified strut, you get 20,000 landings from that rework, then repeat. The intervals are per strut, not per aircraft. Sixth, the AD includes a diagram (image.001.png) which is not reproduced in the source text. That diagram may illustrate the crack location or inspection area; operators must obtain the full AD document to see it. Seventh, the AD was issued in 2006; many Convair aircraft may have been withdrawn from service or sold. An operator who brings a Convair back into Australian registration after being stored must check compliance history for this AD. Eighth, the AD does not allow any alternative inspection method unless approved by CASA. An operator cannot, without approval, use a non destructive test that does not involve disassembly. Ninth, the compliance table uses a "whichever occurs later" clause for modified/new struts: initial inspection is due at 26,000 landings on the part or 6000 additional landings from the effective date, whichever is later. This could be easily miscalculated if the strut already had 24,000 landings at the effective date: then 6000 additional landings gives 30,000, which is later than 26,000. So the initial inspection is at 30,000 landings. An operator who erroneously uses 26,000 could be inspecting too early or too late. Finally, the AD refers to "FAA AD 73-19-11 Amdt 39-1736". That FAA AD may have its own compliance history and may have been superseded by later FAA ADs. The CASA AD does not incorporate later FAA ADs, only later revisions to the service bulletin. So if the FAA issues a new AD that changes the inspection requirement, it is not automatically mandatory in Australia unless CASA adopts it. But the operator must still follow the Australian AD as written, which may be inconsistent with the latest FAA requirements.

Compliance with AD/CONVAIR/27 requires a systematic approach. The first step is to identify whether the operator has any General Dynamics Convair 340 or 440 series aeroplane, including turboprop conversions, in its Australian registered fleet. If none, no action is needed. For each affected aircraft, the operator must determine the configuration of the left hand upper drag strut (nose landing gear). This involves reviewing the aircraft's maintenance records to see if any drag strut modifications have been performed, particularly those listed in Service Engineering Reports 15-4-340-38/440-38 and 15-4-340-44A/440-44A, or Part III and Part IV of General Dynamics Service Bulletin No. 32-8. The operator should also check the part number of the strut to see if it is a new strut (Part No. 340-7310231-1). If records are incomplete, the operator may need to physically inspect the strut to look for stampings or log book entries. Based on that classification, the operator then determines the initial inspection due. For a non modified strut, the initial inspection must be done within 1200 landings after the effective date (26 October 2006) unless that inspection was already done within the preceding 4800 landings. Since this AD is now many years old, any surviving aircraft should have long since passed that initial deadline; the operator should confirm that the inspection was indeed accomplished. If not, the aircraft may be non compliant. For modified or new struts, the initial inspection was due on or before the accumulation of 26,000 landings on that strut or 6000 additional landings after 26 October 2006, whichever is later. The operator must calculate the total landings on the current strut at the effective date (if documentation exists) to see if the inspection was required by a certain point. For any strut that has not yet been reworked per Part IV, a repetitive inspection at intervals not exceeding 6000 landings is mandatory. The operator must set up a tracking system based on landings, not hours. This could be done through the aircraft's flight log, a maintenance software system, or a dedicated worksheet. The operator must ensure that each time the aircraft reaches a multiple of 6000 landings since the last inspection, the strut is disassembled and inspected per the bulletin. To avoid indefinite repetitive inspections, the operator may choose to incorporate Part IV of the service bulletin. This modification likely requires specific parts and procedures; the operator should obtain the FAA approved revision of Service Bulletin No. 32-8 and follow Part IV instructions. Once accomplished, the strut enters a new compliance cycle: an initial inspection is due on or before 20,000 landings following that rework, then every 6000 landings. However, if the operator has incorporated Part IV on all struts, the repetitive inspections are not eliminated; they just reset the interval. Only when a strut has been reworked per Part IV and also has reached the 20,000 landing threshold and then completed that inspection, the AD says "until the strut has been modified in accordance with the provisions of Part IV" - the AD does not clearly say that Part IV eliminates all further inspections. The compliance table says for modified/new struts: perform inspections until the strut has been modified per Part IV. That suggests that once Part IV is done, no further inspections are required. But then it also says for parts that have Part IV rework, perform initial inspection on or before 20,000 landings following each rework, and at intervals not exceeding 6000 thereafter. That seems contradictory. The better reading is that Part IV is the terminating action: once the rework is done, no repetitive inspections are needed. The later provision about 20,000 landings following rework likely applies only if the strut is later repaired or modified again. To be safe, the operator should clarify with CASA. The operator must also keep the service bulletin and any later FAA approved revisions on hand. If conducting the disassembly inspection, the maintenance staff must be trained on the bulletin procedure. If cracks are found, the strut must be replaced with a new or serviceable identical part. The operator must then record the replacement and start a new compliance cycle for the new part. All actions must be documented in the aircraft's maintenance records with reference to AD/CONVAIR/27, the service bulletin revision used, the landing count, and the result. If the operator wishes to use an alternative method, such as a different inspection technique, they must apply to CASA for an alternative means of compliance, providing evidence of equivalent safety. Finally, the operator should periodically check if CASA has superseded this AD or issued a new one that consolidates or changes the requirement. Given the age of the aircraft type, it is prudent to consult with CASA or a maintenance specialist who is familiar with Convair airworthiness directives.