AD/G164/19 Amdt 1 - Fuel Shut-Off Control - Modification

The central concept is the airworthiness directive, a legally enforceable repair or inspection mandate issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations. Non-compliance means the aircraft is no longer considered airworthy and cannot be lawfully operated in Australia. The AD targets a specific unsafe condition: the risk of inadvertently moving the fuel shut-off valve past its intended ON detent to a hidden OFF position. This is a design or rigging problem that the modification corrects by physically limiting the valve's rotation. The stop-plate (P/N A1552-71) is a small mechanical bracket that prevents the control lever from travelling beyond the ON position. The AD mandates installation per a specific service bulletin from the manufacturer, Schweizer Aircraft Corp., dated 1982. That service bulletin provides the engineering instructions. Another key concept is time-in-service (TIS) which measures flight hours. Compliance is measured not by calendar time but by hours flown, which creates different urgency for high-utilisation operators versus low-use aircraft. The AD also introduces a prohibition on certain parts: the Gemini valve P/N 3/4-86-6-RT-6 (A3580-1). This valve may be installed only after the stop-plate modification is completed. The implication is that the valve itself may be safe when used with the correct stop-plate but could be unsafe without it. The amendment introduces a split applicability: Table 1 aircraft (a narrow range of serial numbers per model) retain their original compliance date; Table 2 aircraft (all other G-164 models and serial ranges not previously covered) gain a new compliance deadline. This split reflects the fact that the original AD did not cover all variants. The AD also invokes harmonisation with the United States FAA airworthiness directive system, referencing FAA AD 2007-12-02. The note that the FAA AD supersedes FAA AD 82-07-04 shows that the US regulator updated its requirements and CASA followed. The amendment was issued by a delegate of CASA under statutory authority, as the signature of Charles Lenarcic indicates. The effective date of the amendment is 25 October 2007, meaning inspections and modifications must be scheduled from that date.

This AD directly affects any person or entity owning, operating, maintaining, or modifying a Schweizer (Grumman) G-164 series aeroplane registered in Australia. The model range includes the G-164 (the original model), G-164A, G-164B, G-164B with 73-inch wing gap, G-164B-15T, G-164B-20T, G-164B-34T, G-164C, and G-164D with or without the 73-inch wing gap. The serial numbers are specified in two tables. Table 1 covers a relatively small subset of serial numbers: G-164A 1726A through 1730A; G-164B 335B through 659B; G-164C 1C through 44C; G-164D 1D through 22D. These are aircraft that were already covered by the original 1982 AD. Table 2 covers all other G-164s not listed in Table 1, plus all G-164s (original model), all G-164B-15T, all G-164B-20T, all G-164B-34T, and the remaining G-164As, G-164Cs, G-164Ds, and G-164Bs not in Table 1. So any Ag-Cat operator in Australia must check their aircraft's model and serial number against these tables. The AD also affects maintenance organisations and licensed aircraft maintenance engineers (LAMEs) who must perform the modification, certify it, and make the appropriate logbook entries. Parts suppliers and distributors are affected because the AD prohibits the installation of the Gemini valve unless the stop-plate is fitted, which may reduce demand for that valve or require it to be sold only with a stop-plate. The AD indirectly affects insurers because non-compliance could void hull or liability coverage. It may also affect prospective buyers of used Ag-Cat aircraft, who will need to verify compliance during pre-purchase inspections. Importers bringing G-164 aircraft into Australia will need to ensure the modification is done or scheduled before entry into service. The compliance burden falls most heavily on operators with high-time aircraft because the 100-hour window may arrive quickly. Operators of low-use aircraft may have more calendar time but still must track hours. The amendment expands the pool of affected owners, since many G-164s built after 1982 were not previously required to have the stop-plate. This means owners who thought their aircraft was compliant because it was not listed in the original AD must now carry out the modification. There is no exemption for private or recreational operators; the AD applies equally to all.

The primary duty is the obligation to modify the fuel shut-off control. For owners of Table 1 aircraft, compliance was due within 100 hours TIS after 30 June 1982. This AD does not change that obligation; it reaffirms it. For owners of Table 2 aircraft, the duty is to complete the modification within 100 hours TIS after 25 October 2007. There is no right to delay beyond that period. The second duty is a negative obligation not to install the Gemini fuel shut-off valve P/N 3/4-86-6-RT-6 (A3580-1) on any aeroplane unless the stop-plate is already installed. This duty takes effect as of the next 100 hours TIS after the effective date, meaning that operators who already have that valve installed must ensure it is accompanied by the stop-plate. Operators who wish to install that valve in the future must first install the stop-plate. Operators have the right to use an FAA-approved equivalent stop-plate rather than the exact P/N A1552-71. This provides some flexibility if the original part is unavailable. However, the AD does not specify what constitutes an FAA-approved equivalent; it presumably requires a part approved under a supplemental type certificate or other FAA acceptance. The AD also grants the right to comply early; there is no prohibition on performing the modification before the 100-hour deadline. Owners who are already due for other maintenance may choose to combine the work. There is also an implicit right to seek an alternate means of compliance under the general provisions of the Civil Aviation Safety Regulations, although the AD itself does not mention it. Operators may apply to CASA for an alternative method of compliance if they can demonstrate an equivalent level of safety, but that is a separate regulatory process. The duty to maintain records is inherent: the modification must be entered in the aircraft logbook, including the part number, service bulletin reference, and certification. The AD does not explicitly require notification to CASA upon compliance; normal maintenance records suffice for inspection purposes. The operator has the right to delegate the physical work to a licensed maintenance organisation, but remains ultimately responsible for ensuring compliance before flight. The AD does not create any right to compensation for the cost of compliance from the manufacturer or regulator; it is a safety regulation with no compensation provision.

This AD does not itself specify penalties, but non-compliance with an airworthiness directive issued under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations carries serious consequences. Under the Act, operating an aircraft that is not airworthy is an offence. An AD is legally binding; failure to comply makes the aircraft unairworthy. The maximum penalty for a contravention of a safety regulation under the Act can include fines for individuals and corporations, and in the most serious cases imprisonment for up to five years under section 20A of the Act for reckless conduct causing endangerment. More commonly, CASA may issue infringement notices with fines, or suspend or cancel the registration or airworthiness certificate of the aircraft. The practical enforcement mechanism is that maintenance organisations, pilots, and operators are required to check for compliance during regular inspections and annual reviews. The aircraft's logbook should contain evidence of compliance. If an aircraft is found during a ramp check or a maintenance audit to be non-compliant, the operator can be directed to ground the aircraft until the modification is completed. The AD also has a self-enforcing aspect: because the modification is a prerequisite for the aircraft to be considered airworthy, a pilot who operates without it could be in breach of their licence conditions. The AD references an FAA AD, which may trigger additional enforcement if the aircraft is operated in the United States under a bilateral agreement. The likelihood of prosecution depends on CASA's enforcement priorities, but the high cost of an accident or incident caused by the unaddressed fault would likely attract regulatory interest and potential civil liability. The AD does not grant any amnesty period beyond the 100-hour deadline; once the deadline passes without compliance, the aircraft is in breach. The penalty structure provides a strong deterrent: the cost of the stop-plate (likely a few hundred dollars) plus labour is trivial compared to the potential fines and grounding costs. Enforcement is also indirect: insurers may refuse to cover accidents arising from non-compliance, and purchasers of used aircraft will discount the price to reflect the outstanding modification.

This AD sits within a hierarchy of aviation safety legislation in Australia. The primary enabling law is the Civil Aviation Act 1988, which establishes CASA's power to issue airworthiness directives. The Civil Aviation Safety Regulations (CASR) Part 39 specifically deals with airworthiness directives and makes compliance with them mandatory. This AD is subsidiary to those regulations and has the force of law. It also interacts with CASR Part 43, which governs maintenance standards. The modification must be performed in accordance with the approved service bulletin, and the work must be certified by a LAME or an approved maintenance organisation. The AD does not override any other maintenance requirements; it adds a specific additional requirement. The cross-reference to the FAA AD 2007-12-02 indicates an interaction with foreign aviation law. Australia and the United States have a bilateral airworthiness agreement that allows CASA to adopt FAA ADs with modifications. This AD is explicitly based on the FAA version but tailored for Australia; the note says the FAA AD refers and that it supersedes FAA AD 82-07-04. Operators with aircraft that are also registered in the US or that fly under reciprocal recognition may need to comply with both versions, but this AD harmonises with the FAA version. The AD also implicitly interacts with product liability law. If an accident occurred due to the fuel shut-off issue, the manufacturer could face liability claims, but compliance with the AD may limit that exposure. For the operator, failure to comply could be used as evidence of negligence in a civil suit. The AD also interacts with contracts of insurance. Most hull and liability aircraft insurance policies require the aircraft to be maintained in an airworthy condition in accordance with all applicable ADs. Non-compliance would likely void coverage for any incident involving the fuel valve or related systems, and could potentially void coverage entirely. The AD may also interact with state and territory workplace health and safety laws, especially for aerial application businesses, since the modification relates to an operational safety issue. The AD does not, however, override the Competition and Consumer Act 2010; it simply mandates a specific part, but operators may use equivalents subject to FAA approval, which limits anticompetitive effects. The AD does not interact with the Privacy Act or human rights legislation; it deals solely with mechanical modifications.

The amendment history is contained within the AD itself. The original AD/G164/19 came into effect on 30 June 1982. That original AD was a CASA directive, presumably mirroring the earlier FAA AD 82-07-04. The original AD applied only to a limited set of models and serial numbers, namely those listed in Table 1. The amendment now before us is Amdt 1, which was issued on 29 August 2007 by Charles Lenarcic, a Delegate of CASA, and became effective on 25 October 2007. This amendment does two things. First, it adds significant new applicability by listing in Table 2 all remaining G-164 models and serial numbers that were not previously covered. Second, it updates the compliance requirement for those newly added aircraft, giving them 100 hours TIS after the effective date. For the original Table 1 aircraft, the compliance deadline remains unchanged: 100 hours TIS after 30 June 1982. The amendment also strengthens the prohibition on the Gemini valve by linking it to the stop-plate requirement. The background statement in the AD says: "The original issue of this AD became effective 30 June 1982." The amendment itself is the work of a single amendment; there is no evidence of subsequent amendments. The AD notes that it supersedes FAA AD 82-07-04, through adoption of FAA AD 2007-12-02. The effective date for the FAA AD was 6 August 2007, meaning CASA was acting promptly to harmonise. The amendment was published in the CASA AD compilation for November 2007, as indicated by the "11/2007" notation in the header. The amendment number "Amdt 1" suggests that there was only one amendment to AD/G164/19, and no later amendments have superseded it as of the date of this analysis. The original 1982 AD would have been issued under the earlier regulatory framework. The use of the current CASA delegated authority signature shows that this AD is a post-Corporate model CASA document. There is no mention of any state or territory variation. The amendment history is relevant because some operators may have assumed their aircraft was not subject to any AD because their serial number was outside the original table; this amendment corrects that assumption.

There is no litigation history disclosed in the source text. The AD does not cite any Australian legal cases, and there is no reference to any court challenge to the original 1982 AD or this 2007 amendment. This is not surprising. Airworthiness directives are rarely challenged in court because they are technical safety instruments issued under delegated legislation, and operators generally comply rather than litigate. The cost of compliance is usually far lower than the cost of a legal challenge, and the regulatory framework provides limited grounds for judicial review. A party could theoretically challenge an AD on the basis that it is beyond power, procedurally unfair, or irrational, but such challenges are extremely uncommon in the Australian aviation context. The absence of cited litigation does not mean none occurred, but the source does not contain any. It is likely that the mandated modification was accepted without court contest. The AD's reference to the FAA AD might, however, be relevant in any US litigation involving the G-164 fuel shut-off system, but that would be a separate jurisdiction. The AD itself could be used as evidence in civil litigation if an accident occurred and one party alleged that the modification should have been performed earlier. However, the AD is not itself a subject of litigation. The original FAA AD 82-07-04 and the superseding FAA AD 2007-12-02 might have been the subject of private discussions with the FAA, but no public litigation is recorded. The fact that CASA adopted an amendment 25 years after the original suggests a long period without incident that might have prompted the expansion. Again, no litigation. The AD does not create any private right of action; it is a public law regulatory instrument. Enforcement actions by CASA for non-compliance could be appealed to the Administrative Appeals Tribunal (AAT) or challenged in the Federal Court, but such appeals would be based on the alleged non-compliance rather than the AD's validity. The AD's litigation history, based on the source, is nil.

Several traps await an unwary operator. Different compliance deadlines for different aircraft: Table 1 aircraft were supposed to be compliant by 1982, but many may still be flying without the modification. The AD does not automatically require those Table 1 aircraft to comply now; it says the requirement "remains unchanged as: Within the next 100 hours TIS after 30 June 1982". A strict reading means that if a Table 1 aircraft never had the modification done, it has been non-compliant since 1982, and every flight since then is illegal. That is a serious gotcha: a pre-1982 G-164A in Table 1 that was bought recently and the logbook shows no stop-plate installation is instantly unairworthy. The operator must treat it as a grounding condition, not a 100-hour grace period. Table 2 aircraft get a new 100-hour deadline, but that clock runs from 25 October 2007. For an aircraft that has flown 50 hours since that date, the operator has 50 hours remaining. The prohibition on the Gemini valve is separate: it requires compliance "as of the next 100 hours TIS after the effective date". So if an operator has that valve already installed, they need to ensure the stop-plate is fitted within 100 hours. But if they are fitting the valve for the first time, they must have the stop-plate already installed before the valve goes on. Which stop-plate exactly? The AD says stop-plate P/N A1552-71 or "FAA-approved equivalent". An operator cannot simply use any stop-plate; it must be the exact part or one approved by the FAA. Using a home-made stop-plate would not satisfy the AD. Service bulletin date: The required service bulletin is Schweizer Aircraft Corp. Ag-Cat Service Bulletin No. 78 dated 26 January 1982. That bulletin is now over 40 years old. The operator must obtain a copy and follow it precisely. The bulletin may be difficult to find but is essential. No exception for modified aircraft: If the aircraft has been modified with a different fuel shut-off system that prevents the problem, does that satisfy the AD? The AD does not provide a blanket exemption; it mandates a specific stop-plate. An alternative is only valid if it is an FAA-approved equivalent, not just any other design. Logbook entry: The modification must be recorded with the service bulletin and part numbers. A simple note "stop-plate fitted" may not be deemed sufficient by an inspector; the entry should reference the AD, the bulletin, the part number, and the date and hours at compliance. Foreign aircraft: If a G-164 is imported from the US after 2007, the FAA AD would have required the stop-plate, so it should already be done. But if it was imported earlier, it might not have the modification. The operator must verify regardless. Low-time aircraft: If an aircraft flies only 10 hours per year, the 100-hour deadline may take many calendar years, but the aircraft cannot fly beyond 100 hours TIS after the effective date without compliance. Tracking TIS accurately is essential. Gemini valve already installed: If an operator discovers they have the Gemini valve but no stop-plate, they must not fly unless they can complete the stop-plate installation within the remaining hours. This could cause unexpected downtime.

Compliance requires a systematic approach. Step one: Identify the aircraft. Confirm the model and serial number from the aircraft's registration certificate, type certificate data plate, and maintenance records. Consult Table 1 and Table 2 of the AD to determine which group the aircraft falls into. This determines the compliance deadline. Step two: Check existing records. Has the stop-plate P/N A1552-71 or an FAA-approved equivalent already been installed? Look for a logbook entry referencing Schweizer Service Bulletin No. 78, a part number, and an installation date and hours. If the entry is present and shows compliance within the required timeframe, no further action is needed. Step three: If not compliant, schedule the modification. Obtain the stop-plate from an authorised supplier. The part may be available from aircraft parts suppliers or through the manufacturer's support network. An FAA-approved equivalent must be verified to have FAA acceptance. Do not use a substitute without written evidence of FAA approval. Step four: Perform the installation. Only a licensed aircraft maintenance engineer (LAME) or an approved maintenance organisation should carry out the work. Follow Schweizer Service Bulletin No. 78 exactly. The stop-plate must be fitted to the fuel shut-off valve control mechanism to prevent clockwise movement past the ON position. Step five: Inspect the Gemini valve if fitted. If the aircraft has a Gemini fuel shut-off valve P/N 3/4-86-6-RT-6 (A3580-1), the stop-plate must be installed before further flight, or within the 100-hour TIS window if it was already installed before the AD effective date. If the aircraft does not have this valve, the AD still requires the stop-plate anyway. Step six: Document the work. The LAME must make a detailed entry in the aircraft maintenance logbook. The entry should state: "Compliance with AD/G164/19 Amdt 1: Installed stop-plate P/N A1552-71 (or equivalent) per Schweizer Service Bulletin No. 78. Installation completed at [hours TIS] on [date]." If the aircraft is Table 1 and the work was performed after the 1982 deadline, the entry should note that compliance was overdue and the aircraft was not airworthy for flights in the interim. Step seven: Review ongoing obligations. The AD does not have recurring inspection requirements; it is a one-time modification. However, if the stop-plate is later removed for any reason (e.g. during a major overhaul), it must be reinstalled before flight. Step eight: Maintain records permanently. Keep the logbook entry and a copy of the service bulletin with the aircraft records. These may be requested during a CASA audit or when selling the aircraft. Step nine: Verify during purchase. Buyers of a used G-164 should check for compliance before transfer of ownership. A non-compliant aircraft may need immediate grounding and modification at the buyer's expense. Step ten: Use only approved parts for future installations. Never install a Gemini fuel shut-off valve without first ensuring the stop-plate is present. Purchase of that valve should be accompanied by evidence of stop-plate installation.