{"id":"F2006B06460","name":"AD/R44/10 Amdt 1 - Main Rotor Blade","slug":"ad-r44-10-amdt-1-main-rotor-blade","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47932,"registerId":"commonwealth-F2006B06460-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/R44/10 Amdt 1 - Main Rotor Blade","content":"![](image.001.png)  \nRobinson R44 Series Helicopters\n\nAD/R44/10\n\nAmdt 1\n\n  \n\nMain Rotor Blade 14/98 DM\n\nApplicability: Model R44 helicopters, serial numbers 0002 through 0486, with main rotor blades part number (P/N) C016-1 installed.\n\nRequirement: 1. Inspect the main rotor blade skin around both inboard trim tab alignment rivets as follows, referring to Figure 1 of this Directive:\n\n    (a) Remove all paint around both rivets, exposing an area of approximately ¾ inch in diameter, at the inboard trim tab on the top and bottom of each blade (four places per blade). Use 180 grit or finer abrasive paper, followed by 600 grit or finer paper to eliminate course sanding marks. Sand only in a spanwise direction. Do not use chemical paint strippers.\n\n    (b) Inspect the blade skin around the rivets on the blade upper and lower surfaces (four locations) using a dye penetrant method.\n\nNote 1: Chordwise cracks in the paint up to 2 inches long which are located along either inboard or outboard edge of the trim tab are acceptable.\n\n    (c) Clean the sanded areas prepared with 111-trichloroethane or methyl ethyl ketone and then apply clear lacquer to seal the unpainted areas.\n\nNote 2: Do not bend the inboard main rotor blade tabs from their present position or utilise them for any subsequent blade tracking adjustment.\n\n    2. Thereafter, using a 5-power or higher magnifying glass, visually inspect the upper and lower blade skin surfaces around the inboard trim tab rivets (four locations) for cracks.\n\n    3. Replace main rotor blades P/N C016-1 with main rotor blades P/N C016-2.\n\nNote 3: Robinson Service Bulletin SB-28, dated 18 June 1998, refers.\n\nNote 4: Installation of a set of main rotor blades, P/N C016-2, constitutes terminating action for the requirements of this Directive.\n\nNote 5: FAA Priority Letter AD 98-22-16 refers.\n\nCompliance: 1. Unless already accomplished, within 5 hours time in service after November 4 1998.\n\n    2. Before the first flight of each day, or at intervals not to exceed 5 hours time in service, whichever occurs first.\n\n    3. Replace the main rotor blade before further flight if a crack, other than as described by Note 1, is found when inspected as per requirement 1 or 2, otherwise replace before 1 December 1998.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nThis amendment becomes effective on 4 November 1998.\n\nBackground: The FAA received a report of an incident in which a pilot heard a loud noise and felt severe vibrations while hovering, resulting in a forced landing. Upon inspection, a crack was found in a main rotor blade that started at the mid-span inboard trim tab and ran chordwise to the spar where it turned along the spar for about an inch. The crack originated from a trim tab alignment rivet hole in the blade skin.\n\nSubsequent investigations revealed that the manufacturing process utilised to drill the trim tab alignment rivet holes in the main rotor blade skin can allow a fatigue crack to originate at these holes and propagate in the skin. This condition, if not corrected, could result in failure of the main rotor blade and subsequent loss of control of the helicopter.\n\nThis amendment adds a requirement to replace the affected main rotor blades. Examination of the cracked main rotor blade has indicated that a crack may develop in any of the affected blades. As it has not been possible to determine how quickly the crack progressed, it is not possible to maintain the airworthiness of the blade through inspection. It is therefore necessary to remove the affected main rotor blades from service.\n\nThe initial issue of this Airworthiness Directive became effective on 5 June 1998.\n\n![](image.002.png)\n\nFigure 1","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"This is Amendment 1 to an existing Airworthiness Directive. The original directive (effective 5 June 1998) required only inspections. This amendment significantly expands the scope by adding a mandatory replacement requirement for all affected blades, acknowledging that inspection alone is insufficient to maintain airworthiness. The Background section explicitly states this shift: 'This amendment adds a requirement to replace the affected main rotor blades' and 'it is not possible to maintain the airworthiness of the blade through inspection.'"},"complexity_factors":["Single, specific technical subject matter (main rotor blade inspection/replacement)","Clear sequential requirements (numbered 1-3) with sub-paragraphs","5 defined terms or references (part numbers, serial numbers, chemical names, service bulletin reference)","Multiple compliance deadlines creating conditional obligations (immediate, recurring, and final replacement dates)","Cross-reference to FAA directive and manufacturer service bulletin for context","Technical procedures requiring specialised knowledge (dye penetrant inspection, specific sanding grits, chemical cleaners)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of early Robinson R44 helicopters (S/N 0002–0486) with main rotor blades P/N C016-1 to carry out urgent inspections and to replace those blades with improved P/N C016-2 blades.  \n\nIt responds to a manufacturing defect that causes fatigue cracking near rivets, which led to severe vibration and a forced landing; inspections are temporary risk-mitigation, but replacement is the permanent safety fix."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. The amendment widens the Directive’s scope compared with the initial issue by moving from inspection/monitoring to mandatory removal and replacement of the affected blades. The Background and Requirement 3 make clear that, because crack growth rate could not be reliably determined, simply inspecting blades was judged insufficient; the amended Directive therefore requires replacing P/N C016-1 blades with P/N C016-2 by a fixed date (1 December 1998) and treats installation of the new blades as terminating action. The change increases direct costs and operational impact on owners/operators by forcing replacement rather than permitting indefinite continued service with frequent inspections."},"complexity_factors":["Limited applicability: specific serial number range (0002–0486) and single affected blade part number (P/N C016-1).","Three-tiered requirements: immediate inspection/repair steps (Req. 1), recurring inspections (Req. 2), and mandatory replacement (Req. 3).","Procedural technical detail: exact sanding dimensions (approx. 3/4 inch diameter), grit sequence (180 then 600), sanding direction (spanwise only), prohibition on chemical paint strippers, and specified solvents for cleaning.","Tolerance/exception: Note 1 permits paint-only chordwise cracks up to 2 inches in certain locations.","Terminating action: installation of P/N C016-2 blades ends the Directive obligations (Note 4).","Tight compliance windows: 5 hours time-in-service initial compliance; recurring inspections before first flight or every 5 hours; final replacement deadline of 1 December 1998.","Reference dependencies: cross-references to Robinson Service Bulletin SB-28 and FAA Priority Letter AD 98-22-16.","Operational constraint: explicit prohibition on bending tabs for tracking (Note 2) introduces indirect operational impacts on maintenance practices.","Use of a 5× magnifier for recurring inspections — a specific inspection standard rather than a general visual check.","Inclusion of a figure (Figure 1) for locating inspection points — requires use of the drawing for correct compliance."],"plain_english_summary":"**What this instrument does**\n\n- This Airworthiness Directive applies to Robinson R44 helicopters, serial numbers 0002 through 0486, only when the main rotor blades with part number (P/N) C016-1 are installed. (See “Applicability”.)\n\n- It requires immediate and repeated inspections of the blade skin around the inboard trim tab alignment rivets, specific cleaning and sealing steps, and replacement of all affected blades with the revised part P/N C016-2. (See \"Requirement 1–3\" and Notes.)\n\n**Key actions required (mechanics/operators must do these)**\n\n- Within 5 hours time-in-service after 4 November 1998: remove paint around each of the two inboard trim tab rivets on the top and bottom of each blade (four spots per blade), sand carefully spanwise using 180 grit then 600 grit, do not use chemical paint strippers, inspect with a dye-penetrant method, clean with specified solvents, and seal the bare areas with clear lacquer. (Requirement 1(a)–(c).)\n\n- Thereafter: before the first flight each day, or at intervals not exceeding 5 hours time-in-service (whichever is sooner), visually inspect the four prepared locations on each blade with a 5× (or higher) magnifier for cracks. (Requirement 2.)\n\n- If any crack (other than paint cracks described in Note 1) is found at an inspected location, replace the blade before further flight. In all cases, replace C016-1 blades with P/N C016-2 blades by 1 December 1998. Installation of a set of C016-2 blades ends (terminates) the Directive’s requirements for that helicopter. (Requirement 3 and Notes 4–5.)\n\n- Do not bend the inboard trim tabs from their present position or use them for blade tracking adjustments. (Note 2.)\n\n**Who is affected**\n\n- Owners and operators of Robinson R44 helicopters with serial numbers 0002–0486 that still have main rotor blades P/N C016-1 installed.\n- Maintenance organisations and certificated mechanics who perform inspections and blade replacement.\n\n**Why it matters (the safety mechanism)**\n\n- Investigations found that drilling of the trim tab alignment rivet holes can allow fatigue cracks to start at those holes and propagate in the blade skin. A reported incident involved severe vibration and a forced landing after a blade crack was found originating at a trim-tab rivet. The Directive treats the inspection-only approach as insufficient because the crack growth rate could not be reliably predicted; replacement of the affected blades is therefore mandated. (Background and Requirement 3.)\n\n**Practical effects, incentives and trade-offs**\n\n- Who pays: owners/operators bear the cost of inspection labour, materials and of replacing blades (purchase price, installation labour, and aircraft downtime).\n- Who decides: maintenance providers carry out the inspections and replacements; the Directive leaves no substantive discretion to defer the actions beyond the specified tolerances and time limits.\n- Behavioural change: daily (or every-5-hour) pre-flight inspections in addition to an immediate one, followed by mandatory replacement by a fixed date unless a crack forces earlier replacement.\n- Compliance burden: technical and procedural steps (careful sanding in a specified direction, dye-penetrant inspection, use of specific cleaning solvents, sealing with lacquer, use of a 5× magnifier), and an explicit prohibition on using the tab for tracking adjustments.\n- Market effects: concentrated financial cost on operators of affected serial-numbered helicopters; potential short-term supply/delivery pressure for replacement blades (P/N C016-2) and for qualified maintenance slots. These are the direct implementation costs; the Directive imposes no price controls or subsidies.\n- Risk and trade-offs: the Directive reduces the risk of in-flight blade failure by removing a suspect blade design from service, at the cost of parts, labour and operational interruption. It also reduces reliance on inspection because the rate of crack growth could not be bounded.\n\n**Specific conditional allowances and exceptions**\n\n- Paint-only chordwise cracks up to 2 inches along the inboard or outboard trim tab edge are acceptable (do not require replacement). (Note 1.)\n- Replacing all blades with P/N C016-2 is identified as terminating action for the Directive’s inspection and replacement requirements. (Note 4.)\n\n**Cross-references and documentation**\n\n- The Directive refers to Robinson Service Bulletin SB-28 (18 June 1998) and to FAA Priority Letter AD 98-22-16 for related technical guidance. A figure illustrating the inspection locations (Figure 1) is included.\n\n(References in this summary correspond to the Directive’s \"Requirement\" and \"Note\" numbering and to the Background section.)"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-r44-10-amdt-1-main-rotor-blade","history":"/api/acts/ad-r44-10-amdt-1-main-rotor-blade/history","analysis":"/api/acts/ad-r44-10-amdt-1-main-rotor-blade/analysis","conflicts":"/api/acts/ad-r44-10-amdt-1-main-rotor-blade/conflicts","importantCases":"/api/acts/ad-r44-10-amdt-1-main-rotor-blade/important-cases","documents":"/api/acts/ad-r44-10-amdt-1-main-rotor-blade/documents"}}