AD/UH-1/19 - Tail Rotor Slider

Several technical and regulatory concepts are central to understanding AD/UH-1/19.

CAGE code. The Commercial and Government Entity code is a five‑digit identifier assigned to suppliers, used in federal procurement and maintenance tracking. The AD treats CAGE code 15716 and 26098 as markers of sub‑standard sliders. Specifically, sliders bearing CAGE code 15716 or 26098, or with an illegible or missing code, are presumed suspect and require magnaflux inspection and eventual replacement. Sliders with a legible code other than those two numbers, and which are FAA approved, are accepted without further action. The CAGE code is therefore the primary screening mechanism.

FAA approved part. The AD repeatedly refers to “FAA approved airworthy T/R slider”. This means the part must have been manufactured under an FAA production approval (e.g., Parts Manufacturer Approval or Technical Standard Order) and must be in a condition for safe operation. The AD explicitly notes that T/R sliders manufactured by Forest Scientific, Inc. under a military contract do not meet OEM specifications due to excessive surface roughness from the machining process, making them ineligible for FAA approval. The AD juxtaposes the rough finish of a Forest Scientific slider with the Bell Helicopter Textron slider in Figure 1, which is incorporated by reference.

Magnaflux inspection. This is a magnetic particle inspection method used to detect surface and near‑surface cracks in ferromagnetic materials. The AD requires magnaflux inspection of suspect T/R sliders before further flight and then every 25 hours TIS. The compliance time for the initial inspection is immediate (“before further flight”), while the repetitive inspection interval is 25 hours. This imposes a recurring operational constraint on the helicopter.

Terminating action. Replacing the suspect T/R slider with an FAA approved airworthy slider (either without a CAGE code or with a legible code other than 15716 or 26098) ends all further requirements under the AD. That is, once the replacement is done, the helicopter is no longer subject to the 25‑hour repetitive magnaflux inspections. The AD does not specify any future surveillance beyond the terminating action.

Applicability. The AD applies to Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters, and to Southwest Florida Model SW204, SW204HP, SW205, and SW205A-1 helicopters, but only if they have a T/R slider with part number (P/N) 204‑010‑720‑3 or P/N 204010720‑3 installed. Helicopters with different part numbers or no such slider are not affected.

Effective date. The AD becomes effective on 23 November 2006. Compliance times are measured from that date, not from the date of issuance (12 October 2006). This gives operators a 42‑day window before the first 25‑hour record review requirement begins.

These concepts together define the scope of the directive, the engineering justification (surface roughness leading to crack initiation), and the regulatory pathway to compliance.

The AD directly affects owners and operators of the listed Bell and Southwest Florida helicopter models that have the specified tail rotor slider installed. Given the vintage of the models (UH‑1 variants dating from the 1960s-1970s and Southwest Florida conversions built from original Bell components), the affected population likely includes civil operators, government agencies (e.g., law enforcement, firefighting), agricultural spraying businesses, and vintage helicopter collectors. The AD also affects maintenance organisations that perform inspections and repairs on those helicopters.

Indirectly, the AD affects parts suppliers and distributors. Since sliders removed under the AD are permanently ineligible for installation, the supply of used (but potentially serviceable) sliders from other sources is curtailed. The directive creates a demand exclusively for FAA approved sliders that either have no CAGE code or have a code other than 15716 or 26098. Sliders with CAGE code 15716 or 26098 (likely Forest Scientific parts) are effectively banned, even if they pass magnaflux inspection in the interim. This imposes a compliance cost on the parts market and may force operators to purchase new or overhauled sliders from Bell Helicopter Textron or from alternate FAA approved sources.

Original equipment manufacturer Bell Helicopter Textron is affected in that its parts are deemed acceptable, whereas parts from a competitor (Forest Scientific) are treated as suspect. This creates a market advantage for Bell‑sourced sliders, though the AD’s justification is engineering‑based (surface roughness). The incentive for any alternative manufacturer to enter the market with an FAA approved slider is potentially strong, but the small fleet size may not support a dedicated production line.

The AD also affects the insurance and resale value of affected helicopters. A helicopter that cannot demonstrate compliance with the AD (e.g., because records cannot confirm the CAGE code or a replacement slider has not been fitted within the 1000‑hour/12‑month timeframe) loses airworthiness and cannot operate legally. This may strand aircraft, especially in remote operations where parts supply is slow.

Finally, the AD imposes a record‑keeping burden. Operators must not only perform the physical actions but also document the CAGE code review, magnaflux inspection results, and replacement details. These records must be retained as part of the helicopter’s maintenance history for future compliance checks or during sale.

The AD imposes several explicit duties on the helicopter owner or operator.

Duty to review records. Within 25 hours after the effective date (23 November 2006), the operator must review the helicopter’s maintenance records to determine the CAGE code of the installed T/R slider. If the records do not clearly state the CAGE code, the operator must remove the slider to physically inspect it for the code. This duty arises immediately and is time‑sensitive.

Duty to magnaflux inspect. If the CAGE code cannot be determined, is illegible, is absent, or is 15716 or 26098, then before further flight the slider must be magnaflux inspected for cracks. The first inspection is a “before further flight” action. Subsequently, if no crack is found, the inspection must be repeated at intervals not exceeding 25 hours TIS until the slider is replaced under paragraph 3.

Duty to replace. On or before accumulating 1000 hours TIS or 12 months after the effective date (whichever occurs first), the suspect slider must be replaced with an FAA approved airworthy slider that either has no CAGE code or has a legible CAGE code other than 15716 or 26098. If a crack is discovered during magnaflux inspection, replacement must occur before further flight.

Duty not to re‑install removed sliders. Any T/R slider removed from service under the requirements of this AD is permanently ineligible for installation on any helicopter. This imposes a disposal obligation and prevents the re‑use of suspect sliders in other aircraft, even if they later pass inspection.

Right to use an FAA approved slider. The operator has the right to install any T/R slider that meets the FAA approval criteria and that either lacks a CAGE code or bears a legible code other than 15716 or 26098. The AD does not prescribe a specific supplier; any FAA approved part meeting the specifications is acceptable.

Right to rely on records. If the records clearly show that the installed slider is an FAA approved part with a CAGE code other than 15716 or 26098 (for example, an OEM part from Bell Helicopter Textron), then no inspection or replacement is required. This right is conditional on the code being legible and verifiable.

Absent rights. The AD does not provide a mechanism for operators to seek alternative means of compliance (AMOC) or to extend compliance times. It does not mention any appeal or waiver process. In practice, CASA may grant AMOCs, but the directive itself does not address that. The AD also does not impose a duty to report findings to CASA or the manufacturer; the only duty is corrective action.

The AD itself does not specify monetary penalties or enforcement mechanisms, but as a mandatory airworthiness directive issued under the Civil Aviation Act 1988 (Cth) and the Civil Aviation Safety Regulations 1998 (CASR), non‑compliance constitutes an offence under the Act. Typically, operating an aircraft that does not comply with an applicable AD is a strict liability offence, with penalties that can include fines, suspension or cancellation of an Air Operator’s Certificate or Certificate of Registration, and in serious cases, criminal prosecution if the non‑compliance contributes to an accident.

Under CASR Part 39, which governs ADs, the operator must ensure the aircraft is airworthy before flight. Failure to comply with an AD is a breach of that duty. The penalty for operating a non‑airworthy aircraft under the Civil Aviation Act can be up to 200 penalty units (currently $31,300 per unit, though 2006 values were lower) for an individual and up to 1000 penalty units for a body corporate. Additionally, the Director of Public Prosecutions may bring charges for reckless or negligent conduct if the non‑compliance leads to harm.

Enforcement is typically reactive: CASA or its authorised officers may conduct ramp checks, review maintenance records, or investigate incidents. If a helicopter is found with a T/R slider that has not been replaced or inspected per the AD, the officer can issue a defect notice or ground the aircraft immediately. The operator bears the cost of lost revenue and any rectification before the aircraft can return to service.

There is also a potential civil liability exposure. If a T/R slider fails due to non‑compliance and causes injury or property damage, the operator and maintenance organisation may face tort claims for negligence per se. Compliance with the AD is a minimum standard; failure to adhere to it would be strong evidence of breach of duty of care.

The permanent ineligibility of removed sliders creates an enforcement incentive: once a slider is removed, it cannot be re‑installed, reducing the temptation to “save” a suspect part for other aircraft. However, the AD does not mandate a method of destruction or marking, so operators could theoretically attempt to pass off a removed slider as compliant by altering its CAGE code. That would constitute fraud and separate criminal offences under the Criminal Code.

AD/UH-1/19 directly references FAA AD 2006‑19‑05 (Amendment 39‑14762 dated 5 September 2006). The CASA AD is substantially similar in requirements, but it is a separate Australian instrument. Under CASR 39.015, CASA may issue an AD that adopts a foreign AD with or without amendments. Here, the CASA AD recites the FAA AD as a reference but sets its own compliance times and effective date. Compliance with the FAA AD does not automatically satisfy the CASA AD; an operator must comply with the Australian‑dated requirements.

The AD also interacts with the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations generally. Regulation 11.160 requires that an aircraft must be in an airworthy condition before flight. A non‑compliant T/R slider would render the aircraft unairworthy. Further, CASR Part 47 requires that the Certificate of Registration be accompanied by a maintenance release; a maintenance release cannot be issued if an AD is outstanding.

The AD also intersects with workplace health and safety laws in each state/territory. The magnaflux inspection process may involve hazardous chemicals or electrical equipment, requiring compliance with relevant safety regulations. The operator and maintenance organisation must ensure that personnel performing magnaflux inspection are appropriately trained and that the equipment is calibrated.

If the helicopter is used for commercial air transport, the Civil Aviation Orders (CAO) and Civil Aviation Advisory Publications (CAAP) may impose additional record‑keeping and reporting obligations. For instance, CAAP 1.10 requires operators to have a system to track AD compliance, including repetitive inspections.

Part‑145 maintenance organisations that perform the inspection or replacement must hold the appropriate approvals. The use of an unapproved maintenance organisation could void the AD compliance.

Finally, the AD may have implications for import and export of affected parts or helicopters. If a helicopter with a suspect slider is sold internationally, the buyer’s civil aviation authority may impose its own AD or require equivalent action. The permanent ineligibility of removed sliders effectively creates a restricted parts class.

The source document for AD/UH-1/19 is a single‑page instrument signed by James Coyne on 12 October 2006, effective 23 November 2006. There is no indication within the provided text that this AD has ever been amended. The AD number (AD/UH-1/19) and the date suffix (12/2006) suggest it is the 19th AD issued for the Bell UH‑1 series, dated 2006. No subsequent revisions, extensions, or variations are mentioned.

In practice, ADs may be amended to extend compliance times, add alternative means of compliance, or correct typographical errors. Such amendments are published as separate instruments (e.g., AD/UH-1/19 Amendment 1). However, none are referenced here, and the user has not provided any subsequent documents.

Given the age of the AD (2006), it is plausible that the compliance actions have long since been completed for all affected aircraft still in service. The AD is likely still in effect, but the terminating action (replacement with a compliant slider) means that helicopters that have been modified are no longer subject to the repetitive inspection requirements. The AD remains part of the type design data and must be recorded in the aircraft’s historical records.

The lack of amendment history may also indicate that the AD was correctly scoped and that no industry feedback prompted a relaxation of requirements. However, without access to CASA’s AD register or subsequent issuances, it is impossible to confirm. For the purposes of this deep dive, the AD is treated as a one‑time directive.

The source document does not reference any litigation, and no court cases are named. Given the AD’s narrow scope - a single part on a limited fleet of vintage helicopters - it is unlikely to have generated significant litigation. Most AD compliance disputes are resolved administratively through CASA’s internal review processes or through negotiated compliance agreements.

Potential areas of dispute could include the sufficiency of the engineering justification (the “two accidents” cited are not identified by report), the cost‑benefit analysis of mandating replacement of sliders that pass magnaflux inspection (the AD requires replacement even if no crack is ever found), and the adequacy of the transition timeline for operators with high‑utilisation helicopters (1000 hours may be reached in less than six months for intensive operations). However, none of these challenges are recorded in the provided text.

If any litigation did arise, it would likely be in the form of an appeal to the Administrative Appeals Tribunal (AAT) seeking a variation or stay of the AD, or a judicial review in the Federal Court on procedural grounds. The AD was issued under delegated authority; a challenge could argue that the delegate considered irrelevant matters or failed to consider the availability of alternative parts. Again, no such cases are mentioned.

The absence of litigation history in the source is not surprising. ADs are generally complied with by the aviation community to maintain airworthiness certifications, and the cost of challenging an AD often exceeds the cost of compliance, especially when the fleet size is small. The lack of litigation may also indicate that the AD was well‑reasoned and that no party had a sufficient economic interest to mount a legal challenge.

Several aspects of AD/UH-1/19 may catch operators off guard.

Simultaneous compliance times. The AD imposes a 25‑hour record review requirement and a separate 1000‑hour/12‑month replacement requirement. The 25‑hour clock starts from the effective date, but the magnaflux inspection and replacement times may overlap. If a operator fails to perform the record review by 25 hours, they may be flying with an unverified slider, exposing them to immediate grounding risk if inspected.

CAGE code ambiguity. The AD treats sliders with no CAGE code differently from those with a legible code other than 15716/26098. Bell Helicopter Textron sliders have a vibro‑etched part number but do not have a CAGE code marking on the part. The AD Note 3 explicitly states that these sliders are exempt from the CAGE code requirement and are acceptable. An operator unaware of this nuance might unnecessarily magnaflux a Bell slider. Conversely, a slider with any other manufacturer’s code that is legible and FAA approved is also acceptable without further action. The burden is on the operator to correctly identify the part.

Permanent ineligibility of removed sliders. Once a slider is removed under the AD, it cannot be installed on any helicopter, even on a different model that might not be affected by the AD. This creates a waste disposal issue and means that a slider that survives 1000 hours of inspection with no cracks must still be scrapped. This destroys value and may frustrate operators who see no apparent defect.

Interpreting “before further flight”. The magnaflux inspection requirement for suspect sliders is “before further flight”. If the helicopter is already airborne when the 25‑hour review identifies a suspect slider, the helicopter must land and not take off again until the magnaflux is done. This could cause operational disruptions, especially in remote areas where inspection equipment is not available.

No allowance for post‑replacement continued airworthiness. Once the terminating action is done, the AD’s requirements cease. But the operator still has ongoing airworthiness obligations under CASR Part 42 or Part 91, including any maintenance requirements for the new slider. The AD does not mandate any additional inspections for the replacement slider beyond standard practices.

Parts sourcing risk. With only one FAA approved slider manufacturer clearly identified (Bell Helicopter Textron), operators may face supply shortages, price increases, or long lead times. The AD does not require manufacturers to support the fleet indefinitely. An operator who delays replacement until the last moment may be grounded while waiting for parts.

Record‑keeping trap. The AD requires “review of the helicopter records to determine the CAGE code”. If the records are incomplete, the operator must remove the slider to visually inspect it. Removing a slider on an older helicopter may reveal additional issues (corroded fasteners, damaged parts) that expand the work scope and cost.

Interaction with other ADs. The AD notes that it refers to FAA AD 2006‑19‑05. If the helicopter also operates under a different civil aviation authority (e.g., EASA), additional requirements may apply. The operator must check the state of registry’s adoption.

Effective date versus compliance start. The AD becomes effective on 23 November 2006, but the first compliance action (record review) is “within 25 hours after the effective date”. An operator who flies 25 hours in the first week must rush to complete the review. Those who fly only 10 hours per month have more time for the review but still face the 1000‑hour/12‑month window for replacement.

Compliance with AD/UH-1/19 requires a systematic process, best documented in a worksheet or log entry. The steps are directly derived from the Requirement paragraph.

1. Record review (within 25 hours of 23 November 2006). Obtain the helicopter’s maintenance records. Identify the installed T/R slider part number and look for the CAGE code. If the records show a legible CAGE code other than 15716 or 26098, and the part is FAA approved, note this in the records as “AD/UH-1/19 - no further action - CAGE code XXXX, FAA approved”. If the records are ambiguous, proceed to step 2.

2. Physical inspection for CAGE code (if records insufficient). Remove the T/R slider per the manufacturer’s instructions. Clean the part and visually examine it for a stamped CAGE code. If the code is legible and not 15716 or 26098 (and the part is FAA approved), re‑install and record. If the code is illegible, absent, or is 15716 or 26098, proceed to step 3.

3. Magnaflux inspection (before further flight). Perform a magnetic particle inspection on the slider in accordance with ASTM E1444 or equivalent. If a crack is found, the slider must be replaced immediately with an approved slider before flight. If no crack is found, re‑install the slider and note that the helicopter must undergo repetitive magnaflux inspections every 25 hours TIS until replaced.

4. Scheduled replacement (on or before 1000 hours TIS or 12 months from 23 November 2006). Obtain an FAA approved airworthy T/R slider that either has no CAGE code or has a legible CADE code other than 15716 or 26098. The preferred source is Bell Helicopter Textron (P/N 204‑010‑720‑3 or 204010720‑3) or any other FAA approved supplier. Install the new slider per the maintenance manual. Update the records to reflect the installation, including the new slider’s part number, CAGE code (if any), and the date and TIS at installation.

5. Disposal of removed slider. Permanently mark the removed slider as “Not airworthy - per AD/UH-1/19”. Dispose of it in a manner that prevents re‑use (e.g., cut the part, mutilate, or return to the supplier as scrap). Do not sell or transfer the slider to another operator.

6. Record final compliance. Make an entry in the helicopter’s logbook stating that the terminating action has been completed, referencing AD/UH-1/19 and the replacement part details. No further inspections are required under this AD.

7. Ongoing surveillance (if replacement not yet done). For any helicopter that still has a suspect slider installed pending the 1000‑hour/12‑month deadline, the operator must schedule a magnaflux inspection every 25 hours TIS. Use a tracking system to ensure the interval is not exceeded. The cost and downtime of these repetitive inspections should be factored into operational planning.

Operators should consult a Part‑145 maintenance organisation accredited to perform magnaflux inspection and Bell helicopter maintenance. All records should be retained indefinitely as part of the aircraft’s permanent history, as future buyers or regulators may ask to see compliance evidence even after the AD is closed out.