AD/PHZL/44 Amdt 9 - Propeller Attachment Bolts

Propeller attachment bolts. The core subject of the AD. Two specific part numbers are identified: the older P/N A-2047 bolt and the newer P/N P/N B-3339 bolt. A-2047 bolts bear a letter "H" stamped inside a triangle on the bolt head. B-3339 bolts have the part number stamped inside the cupped head. The AD mandates a gradual replacement of A-2047 bolts with B-3339 bolts (or equivalents). The distinction matters because the torque procedures differ: A-2047 bolts must be torqued dry (100-125 ft-lbs) whereas B-3339 bolts are torqued with lubricant applied (100-105 ft-lbs). The lubricant changes the torque-to-tension relationship, which is why the final torque value is slightly lower but the preload is equivalent.

Equivalent approved serviceable bolts and washers. A key term in Requirement 1 and 2. The AD permits the use of bolts and washers that are not necessarily the exact Hartzell part numbers, provided they are approved as serviceable equivalents. The source does not define what constitutes "equivalent approved" , it does not say whether this requires CASA approval, a design change approval under Part 21 of the Civil Aviation Safety Regulations (CASR), or simply adherence to Hartzell's own service instructions. Note 2 points to Hartzell Service Instructions No. 140A, Revision 9, dated 30 March 2005, as "the latest service information that pertains to the subject of this AD." That document likely provides guidance on identifying approved equivalent parts. However, the AD itself does not incorporate the service instructions as mandatory text; it merely references them. That creates ambiguity: if an operator uses a bolt from a third-party manufacturer that is not explicitly approved by Hartzell, there is risk that CASA could deem the installation non-compliant.

Torque sequences. The AD mandates two sequences for B-3339 bolts. Sequence A is a cross-pattern tightening (not described in text but standard practice), used for initial torque to 40 ft-lbs and then to 80 ft-lbs. Sequence B is another pattern for final torque to 100-105 ft-lbs. This stepwise approach ensures even clamping force and avoids warping the flange. For A-2047 bolts (when torque-checking only), no sequence is specified; the check simply requires a torque wrench and adapter, and each bolt must turn at the required torque or above. If any bolt fails to reach 100 ft-lbs, all eight must be replaced.

Before further flight. A compliance trigger with immediate effect. Requirement 2(b) states that if a torque check reveals any bolt below 100 ft-lbs, the operator must replace all eight bolts and washers before further flight. That means the aircraft is effectively grounded until the replacement is completed. This imposes a potentially costly and inconvenient delay, especially if the replacement requires procurement of parts that may not be immediately available. The AD does not provide any exceptions for ferry flights to a maintenance base or for temporary relief.

300 hours time-in-service. The initial compliance window for torque checking existing A-2047 bolts. Note that "time-in-service" is not defined in the AD itself but is a standard aviation term referring to the total time the aircraft has been in flight since manufacture or since the last overhaul of the component. This term may cause confusion if the operator counts "time-in-service" on the propeller separately from on the airframe. The AD does not address whether the 300 hours runs from the effective date counting only flight hours, or whether it resets if the propeller is removed and reinstalled. Compliance should be tracked carefully.

Safety wire. After torquing, all bolts must be secured with safety wire "in an approved manner." The AD does not prescribe the method; standard aircraft maintenance practices (e.g., MS33591) or manufacturer instructions would apply. Failure to safety-wire properly could lead to bolt loosening due to vibration, defeating the purpose of the AD.

The AD directly affects the owners, operators, and maintenance providers of any aircraft that has an engine equipped with one of the seven listed Hartzell turbine propeller models. These are not light aircraft propellers; they are typically used on larger turboprop aircraft such as the Cessna Caravan, Beechcraft King Air 90 and 200 series (when fitted with Hartzell four-blade or five-blade propellers), and various Piper Cheyenne models. The AD is model-specific, so only those operators with these exact model numbers are caught. But because the AD applies to the propeller as a component, it also touches aircraft manufactured after the AD effective date that are fitted with these propellers , either as new or as serviceable replacement units.

The compliance burden falls primarily on aircraft maintenance organisations (AMOs) and licensed aircraft maintenance engineers (LAMEs) who physically perform the work. For Requirement 1 (new installations), the installer must follow the prescribed lubrication, torque, and safety-wire procedures. For Requirement 2 (existing A-2047 bolts), the maintenance provider must first identify the bolt type using the visual markings (triangle H vs. part number stamp) and then either perform the torque check or proceed with the replacement.

A smaller but still affected group is parts suppliers and distributors. The AD mandates eventual replacement of all A-2047 bolts with B-3339 bolts (or equivalents). That creates demand for B-3339 bolts and A-2048-2 washers, or equivalent products from other manufacturers. Suppliers must ensure they are stocking approved parts and can provide traceability documentation. The AD allows "equivalent approved serviceable bolts and washers" , that opens a market for alternative parts, but only if they have been approved by either Hartzell or CASA. The approval process itself (likely requiring FAA or EASA approval given the international nature of these parts) imposes costs on new entrants, potentially limiting competition.

From an economic perspective, the AD operationalises a classic regulatory cost: it forces a capital expenditure on parts and labour even if the existing A-2047 bolts are perfectly functional (as assumed by the allowance to defer replacement until next disassembly). The cost is unavoidable. For a fleet operator with many aircraft fitted with these propellers, the cumulative cost of replacing eight bolts per propeller, plus the labour for torque checks and interim replacements, could be significant. The AD does not mention any compensation scheme for these costs, nor does it require CASA to consider economic impact before issuing the AD. The free-market prior would ask: is the mandated replacement of all A-2047 bolts , even those that have passed torque checks and are deemed airworthy , a proportional response, or could the same safety outcome be achieved by periodic torque checks alone? The AD designers have chosen to mandate eventual replacement, eliminating the bolt type entirely. That may be based on known failure modes of A-2047 bolts (e.g., fatigue cracking) that torque checking cannot detect. But the AD does not provide any failure data or engineering justification beyond the brief background statement about propeller separation risk.

Passengers and insurers are indirectly affected. Passengers benefit from a reduced risk of catastrophic propeller separation. Insurers gain a known risk mitigation, which may lower loss reserves but also could lead to higher premiums if the AD creates new potential points of non-compliance liability.

The AD imposes specific duties on the person performing the installation or maintenance , in practice the maintenance organisation or engineer. The duties vary by the two regimes.

For a new or serviceable propeller installation (Requirement 1), the duties are:

• Clean both engine and propeller flanges and ensure they are completely and truly contacted.
• Apply lubricant (MIL-T-83483 or Hartzell P/N A-3338) to the threads of the eight bolts and to the flat surface of the washers. The AD allows the same lubricant to be applied to the remainder of the bolt if desired.
• Install the eight bolts and washers (P/N B-3339 and P/N A-2048-2, or approved equivalents) through the engine flange into the propeller flange.
• Torque the bolts in a two-stage sequence: Sequence A to 40 ft-lbs then 80 ft-lbs; Sequence B to final torque of 100 to 105 ft-lbs.
• Safety wire all bolts in an approved manner.

For existing installations with A-2047 bolts (Requirement 2), the duties are:

• Within 300 hours time-in-service after 7 July 2005, perform a torque check on all eight bolts using a dry thread condition (no lubricant). The acceptable torque range is 100 to 125 ft-lbs.
• If any bolt is below 100 ft-lbs, remove all eight bolts and washers and replace with B-3339 bolts and A-2048-2 washers (or equivalents) before further flight.
• If all bolts are within range, replace all eight bolts and washers at the next propeller disassembly.

There are also duties related to identification: the person performing the check must recognise the difference between A-2047 and B-3339 bolts using the visual cues described in Note 1.

Rights. The AD confers a limited right on the operator to use equivalent approved parts rather than the exact Hartzell part numbers. This is a potentially valuable flexibility because it allows the use of alternative parts that might be cheaper or more readily available. However, the AD does not specify who determines equivalency or what standard applies. The operator therefore has a right to substitute provided they can demonstrate that the substitute part is approved by Hartzell, CASA, or perhaps an international airworthiness authority. In practice, this right may be illusory if the only approved equivalents are OEM Hartzell parts. The AD also implicitly grants the right to defer replacement of A-2047 bolts until the next propeller disassembly, provided the torque check is passed. This is a significant practical right, as it avoids unnecessary grounding.

The AD does not confer any right of appeal or review within the AD itself. However, as a legislative instrument under the Civil Aviation Act 1988, affected persons may be able to seek merits review in the Administrative Appeals Tribunal or judicial review in the Federal Court. The AD also does not establish any duty on CASA to provide economic support or to consider individual hardship.

The AD itself does not prescribe specific penalties. The enforcement framework derives from the parent legislation: the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations (CASR) made under it. Non-compliance with an airworthiness directive is a breach of the Act or regulations, depending on how the AD is given force. Typically, an AD is issued under regulation 37 of the Civil Aviation Regulations 1988 (CAR 1988) or under the transitional provisions of CASR. Contravention can result in civil penalties (financial) and criminal offences (fines and imprisonment) for individuals and corporations.

The maximum penalties are substantial. For an individual, a contravention of a safety regulation may attract a penalty of up to $13,750 fine (as at 2024 starting rates) and/or imprisonment for up to 2 years for reckless conduct. For a corporation, fines can be tens of millions under the relevant legislative instruments. Moreover, CASA can issue infringement notices (on-the-spot fines) for certain breaches, which for safety matters can be around $1,100.

Beyond direct financial penalties, the practical enforcement consequences are severe: CASA can ground the aircraft (issue an airworthiness limitation), suspend the airworthiness certificate, or suspend the maintenance organisation's approval. For a commercial operator, being grounded even for a day can cause significant revenue loss and damage to customer goodwill. The AD does not include any grace period or leniency provisions; it mandates "before further flight" in one scenario, meaning immediate compliance is expected.

The enforcement risk is not trivial. If an operator does not perform the 300-hour torque check and later a defect is found (e.g., during an accident investigation), CASA could treat that as deliberate non-compliance. Even if the AD is not routinely inspected, the operator bears the compliance risk.

From a public choice perspective, the AD creates a strict liability obligation: the operator must comply regardless of knowledge or fault. That is efficient for safety but imposes a burden on operators who may be unaware of the AD , a problem mitigated by CASA's AD publication system and subscription services. The AD does not provide for any defence of due diligence or reasonable steps, typical for absolute-liability safety regulation.

This AD is part of a hierarchy of aviation safety regulation. It is issued under the Civil Aviation Act 1988 and sits alongside other CASA-made instruments such as airworthiness notices, directions, and exemptions. The AD itself notes that the FAA has a parallel airworthiness directive: FAA AD 83-08-01 R2 Amendment 39-14043. That suggests that Hartzell's propeller design is widely used internationally and both regulators have issued similar mandates. For an Australian operator who imports an aircraft from the United States, the FAA AD will likely be accepted as equivalent if the aircraft is operated under a US registry, but once imported into Australian register, the CASA AD takes effect. Compliance with the FAA AD does not automatically satisfy the CASA AD unless both requirements are identical , which they appear to be in substance, but the CASA AD includes specific part numbers and torque values that may differ slightly. Operators should verify alignment.

The reference to Hartzell Service Instructions No. 140A, Revision 9 (March 2005) means that the AD incorporates by reference industry technical information. While the service instruction itself is not a legislative instrument, the AD mandates compliance with the procedures it describes. If the service instruction is updated after the AD effective date, the operator must check whether CASA has issued a new amendment to the AD to incorporate it, or whether the AD&;#x27;s reference is static to the March 2005 revision.

The AD operates alongside general aircraft maintenance regulations under CASR Part 42 (Continued Airworthiness) and Part 145 (Approved Maintenance Organisations). An AMO must include compliance with all applicable ADs in its maintenance schedules. Failure to track AD compliance is itself a breach of those regulations. The AD also interfaces with the aircraft flight manual (AFM) and any engine manufacturer's installation manual , though those documents are not legislation, they may contain supplementary procedures.

State and territory work health and safety laws also apply to maintenance work. The torque and safety-wire operations are standard, but the use of lubricants (MIL-T-83483) requires handling in accordance with safety data sheets. The AD does not impose any additional WHS duties beyond what already applies.

From a private law perspective, if a propeller separation occurs due to non-compliance with the AD, the operator or maintenance organisation could face civil liability for negligence or breach of statutory duty. The AD would be strong evidence of the standard of care expected.

The source document is AD/PHZL/44 Amendment 9, effective 7 July 2005. The Background section provides limited history: Amendment 7 mandated compliance with Issue 6 of Hartzell Service Instructions 140A. Amendment 8 mandated compliance with Hartzell Alert Service Bulletin A203, specifically for aircraft fitted with Hartzell B5MP propellers. Amendment 8 became effective in 1994. The Background also states: "Current amendment allows the use of equivalent approved serviceable bolts and washers." That appears to be the key change introduced in Amendment 9 compared to earlier versions. Beyond that, the source does not detail the complete amendment chain (e.g., Amendments 1 through 6, or the initial AD issuance date). The note referencing FAA AD 83-08-01 R2 gives a date of possibly 1983 for the original US directive.

The AD references Hartzell Service Instructions No. 140A, Revision 9, dated 30 March 2005. That suggests that the AD revision was timed to align with a new revision of the service instructions. Amendment 9 was signed on 19 May 2005 and published as AD/PHZL/44 Amdt 9 with the number 7/2005.

Given the limited source information, any extrapolation beyond these facts would be speculative. What can be observed is that the AD has evolved over at least nine amendments, spanning from before 1994 (when Amdt 8 became effective) to 2005. The focus shifted from general compliance with service instructions (Amdt 7) to a specific alert bulletin for certain models (Amdt 8) and then to introducing part-number equivalency (Amdt 9). This reflects a common regulatory pattern: tightening requirements initially, then adding flexibility as experience and alternate parts become available.

The amendment history also indicates that CASA has periodically reviewed the AD in response to manufacturer updates. The AD is not static. Operators and maintainers must ensure they are working with the latest amendment, as an older amendment may have different torque values, part number requirements, or compliance times. For instance, an operator who was compliant under Amdt 8 (which required compliance with SB A203) might not be compliant under Amdt 9 if they did not also replace bolts when required. The AD itself does not contain a savings clause or grace period for prior compliant installations.

The AD itself does not mention any litigation. No case law concerning AD/PHZL/44 (or its amendments) is cited in the document. Given that the AD is now over 18 years old (as at 2024), if there had been a significant judicial challenge, it would likely be recorded in aviation law databases. I am not aware of any reported Australian case specifically dealing with this AD. Nonetheless, there have been general challenges to CASA's power to issue ADs under the Civil Aviation Act, but those are not documented in this source.

The absence of litigation could be because the AD is highly technical and narrow in scope, affecting a small pool of operators. The compliance requirements are clear, and the safety justification is strong enough that no party has disputed the need for it. Alternatively, disputes may have been resolved informally through CASA's enforcement discretion or through exemption applications, which are not public unless a tribunal case arises.

The AD also cross-references the FAA's parallel AD. In the United States, there have been occasional disputes over FAA ADs on propeller attachment bolts, but none specific to Hartzell models cited here that are widely known. The legal validity of incorporating service instructions by reference has been challenged in other contexts, but not specifically for this AD.

Therefore, the safe conclusion is that there is no recorded litigation directly concerning AD/PHZL/44 Amdt 9. This does not mean there has never been a compliance dispute , CASA may have issued infringement notices or taken enforcement action that was not publicly reported , but no authoritative judicial interpretation exists.

The AD contains several traps that could catch the unwary operator or maintainer.

Instant grounding for low torque on a single bolt. Requirement 2(b) says: "During torque check per Requirement 2 (a) of this AD, if the torque of any one of the bolts is found to be less than 100 ft.-lbs., remove all eight bolts and washers and replace with P/N B-3339 bolts and P/N A-2048-2 washers, or other equivalent approved serviceable bolts and washers, using procedures described in Requirement 1 of this AD." That means if you find just one bolt slightly under torque, you cannot simply re-torque that bolt or replace just that bolt. You must replace all eight bolts and washers. This is a significant cost and logistical burden. The reason is likely that if one bolt is below torque, it indicates either overall improper installation or fatigue, and replacing all ensures uniformity. But the AD does not state this rationale.

Dry vs. lubricated torque. A classic trap: For the torque check of A-2047 bolts, the AD explicitly says "do not use any lubricant with the P/N A-2047 bolts." If a mechanic accidentally applies lubricant and hits the wet torque value (100-105 ft-lbs), the preload will be too low and the bolt may not be adequately secured. Conversely, for the final installation of B-3339 bolts, lubricant is mandatory. Applying the wrong lubrication can lead to incorrect preload and possible failure.

Identification of bolt types. Note 1 explains that a P/N A-2047 bolt has the letter "H" stamped inside a triangle on the bolt. A P/N B-3339 bolt has the part number stamped inside the cupped head. The mechanic must be able to distinguish them. Using a visual check alone could be mistaken if the stamp is worn or dirty. The AD does not permit testing or alternative identification methods.

Compliance times ambiguity. For Requirement 2(a), the compliance is "within the next 300 hours time-in-service, after the effective date of this AD." Does that mean the torque check must be completed 300 flight-hours after 7 July 2005, or within 300 hours of the AD taking effect (regardless of when the hours are flown)? Standard interpretion would be "the next 300 hours service" i.e., the first 300 hours flown after 7 July. But if the propeller has already accumulated many hours before the AD, there is no requirement to perform the check earlier than the next 300 hours. However, note that Requirement 2(b) for torque failure says "before further flight" , if the check reveals low torque, the aircraft cannot fly until replacement. So the operator cannot avoid the check; if they wait until 290 hours and then discover low torque, they face grounding.

Replacement at next propeller disassembly vs. "next disassembly of the propeller". Requirement 2(c) says "at next propeller disassembly, after the effective date of this AD, remove all eight bolts and washers and replace ..." This assumes that the next disassembly occurs at some point after the torque check and before the propeller reaches its life limit. But what if the propeller never needs disassembly during the ownership period? The operator is then in indefinite compliance , the AD does not set a calendar or flight-hour time limit for replacement if the torque check passes. However, the propeller will eventually need disassembly for overhaul or repair, and at that point replacement must occur. This may create a situation where a new operator buys an aircraft with the old bolts still installed and then finds out the AD applies, but they can legally operate as long as the torque check is current. That is not a trap, but it requires careful documentation to show the torque check was performed.

Equivalent approved parts. The AD allows "other equivalent approved serviceable bolts and washers." It does not define what makes a part equivalent or who approves it. In practice, CASA may accept parts approved by the FAA (via an FAA Parts Manufacturer Approval) or by EASA. But the operator bears the risk of proving equivalency if CASA audits. Using a part not clearly marked as approved could be considered non-compliance.

AD self-termination for compliant installations. Requirement 1(f) says: "Once the propeller is installed with P/N B-3339 bolts and P/N A-2048-2 washers or other equivalent approved serviceable bolts and washers, this AD no longer applies." That is clear. But if you install B-3339 bolts and later need to remove the propeller for any reason, the AD will apply again when you reinstall the propeller, because the reinstallation is a new or serviceable propeller installation. So the AD is not a one-time fix; it applies each time the propeller is installed on the aircraft.

Compliance requires a systematic approach tailored to the type of installation.

Step 1: Identify the propeller model and bolt type. Determine if the aircraft has one of the seven listed Hartzell turbine propeller models. If yes, note whether the current attachment bolts are P/N A-2047 (triangle with H) or P/N B-3339 (part number in cupped head) or other approved equivalents. Record the part numbers.

Step 2: Determine the applicable regime based on the installation scenario.

• New installation or replacement with a serviceable propeller after 7 July 2005: Follow Requirement 1 fully. Obtain P/N B-3339 bolts and P/N A-2048-2 washers (or equivalent approved parts). Ensure the engine and propeller flanges are clean. Apply lubricant (MIL-T-83483 or Hartzell P/N A-3338) to the threads and to the washer flat surfaces. Install the bolts and washers. Use a calibrated torque wrench. Torque in Sequence A: first to 40 ft-lbs, then to 80 ft-lbs. Then apply Sequence B: final torque to between 100 and 105 ft-lbs. After torquing, safety wire all bolts using an approved method (e.g., lock wire per standard practices). Record the torque values and part numbers in the aircraft maintenance log. Once done, the AD no longer applies to that installation (per 1(f)). If the propeller is later removed and reinstalled, the AD will apply again to that reinstallation.

• Existing installation with A-2047 bolts: Perform a torque check within 300 hours time-in-service after 7 July 2005. Use dry threads (no lubricant). Torque check each of the eight bolts using a torque wrench and appropriate adapter. Record the torque value for each bolt. If any bolt reads below 100 ft-lbs, you must replace all eight bolts and washers with P/N B-3339 and A-2048-2 (or equivalents) before further flight. Use the procedures in Requirement 1 (lubrication, torque sequences, safety wire). If all bolts read between 100 and 125 ft-lbs (the acceptable range for dry bolts), you may defer the replacement until the next time the propeller is disassembled for any reason. At that disassembly, replace all eight bolts and washers. Note: you cannot wait beyond that disassembly, but there is no calendar limit. Document the torque check and any replacement in the aircraft logbook.

Step 3: Maintain records. Keep clear records of all torque checks, replacements, and the torque values obtained. This demonstrates compliance to CASA or to a purchasing party if the aircraft is sold.

Step 4: Monitor for amendments. CASA may issue further amendments to this AD. Check CASA's AD database periodically. The AD number is AD/PHZL/44. Always refer to the latest amendment.

Step 5: Use approved parts. If using "equivalent approved serviceable bolts and washers," ensure you have written evidence of approval (e.g., from Hartzell service instructions, or from the part manufacturer's FAA PMA letter, or from CASA approval). Keep that evidence with the maintenance records.

Practical tip: Given the potential for grounding if a bolt is under torque during the first check, consider performing the torque check early in the 300-hour window, while you have time to order replacement bolts if needed. Also, have the replacement bolts and washers on hand before the check, in case they are needed. This avoids operational disruption.

Cost estimate: The parts (eight bolts and washers) may cost a few hundred dollars plus labour (1-2 hours). The torque check itself is quick if the spinner can be removed. Non-compliance risks could be far higher in penalties and grounding costs.