{"id":"F2006B06243","name":"AD/PITTS S-2/14 - Fuselage Lower Longerons","slug":"ad-pitts-s-2-14-fuselage-lower-longerons","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47201,"registerId":"commonwealth-F2006B06243-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PITTS S-2/14 - Fuselage Lower Longerons","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPitts S-1 and S-2 Series Aeroplanes\n\nAD/PITTS S-2/14 Fuselage Lower Longerons 11/86 DM\n\nApplicability: All models incorporating spring leg main landing gear and which have exceeded 200 hours time in service.\n\nRequirement: Inspect the fuselage lower longerons for cracks in the area of the MLG leg attachment, left and right sides. Pay particular attention to the weld clusters immediately forward and aft of the MLG leg.\n\nCompliance: Within 50 hours time in service after 6 October 1986 and thereafter at each issue of a new Maintenance Release.\n\nBackground: One longeron has been found completely severed, and several have been found cracked, at the weld cluster aft of the MLG leg, at times in service ranging from 200 hours to 600 hours. One aircraft was also found to have cracks at the forward cluster.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive’s stated scope is limited to Pitts S-1 and S-2 series aeroplanes that incorporate spring-leg main landing gear and have exceeded 200 hours time in service. The text does not indicate any expansion or narrowing of that scope beyond the stated applicability."},"complexity_factors":["Narrow technical scope (specific part: fuselage lower longerons at MLG-leg weld clusters).","Clear applicability criteria (spring-leg MLG models with >200 hours TIS).","Simple, time-bound compliance schedule (50 hours after specified date, then at each Maintenance Release).","No layered compliance options or alternative methods specified.","Operational dependence on maintenance-release timing increases practical variability but not legal complexity."],"plain_english_summary":"What this does (mechanical change)\n\n- Requires visual inspection of the fuselage lower longerons (the structural members running along the bottom of the fuselage) on Pitts S-1 and S-2 series aeroplanes that have spring-leg main landing gear and have exceeded 200 hours time in service. (Applicability; Requirement)\n- The inspection must look for cracks on both left and right longerons in the area where the main landing gear (MLG) leg attaches, with particular attention to the weld clusters immediately forward and aft of the MLG leg. (Requirement)\n- Timing: the first inspection must be done within 50 hours time in service after 6 October 1986, and inspections must be repeated at each issue of a new Maintenance Release. (Compliance)\n\nWhy it was introduced (stated purpose)\n\n- The directive was issued because inspections found one longeron completely severed and several cracked longerons at the weld cluster aft of the MLG leg, with those cracks appearing between about 200 and 600 hours time in service; one aircraft also had cracks at the forward cluster. The background information is the stated reason for the inspection requirement. (Background)\n\nWho it affects and who pays\n\n- Directly affects owners/operators of Pitts S-1 and S-2 aeroplanes that have spring-leg main landing gear and that have exceeded 200 hours time in service. (Applicability)\n- The owners/operators bear the cost of carrying out the inspections and any repairs or grounding time that follow from findings. (Requirement; Compliance)\n\nHow it works in practice (incentives, compliance burden, decision points)\n\n- The rule creates a recurring maintenance obligation tied to the maintenance-release cycle: inspectors must check the specified weld clusters initially within a short hours window (50 hours after the specified date) and thereafter whenever a new Maintenance Release is issued. This imposes recurring inspection time and possible repair costs on affected owners/operators. (Compliance)\n- The inspection focuses on a small, well-specified area (weld clusters around the MLG-leg attachment), which narrows the physical scope of work but still requires competent maintenance personnel able to detect and assess cracks. (Requirement)\n- If cracks or a severed longeron are found, repair or replacement work will be required before the aircraft is returned to service; that work and any associated downtime are additional costs to owners/operators. (Background; Requirement)\n\nTrade-offs, implementation risks and administrative features\n\n- Trade-off: the directive trades ongoing inspection and repair costs and aircraft downtime for the intended reduction in the risk of structural failure at the MLG attachment area. (Background; Requirement)\n- Implementation risk: inspections can only detect visible cracks; smaller or internal defects may be missed without more intrusive inspection methods. The issuer has specified visual attention to the weld clusters but not a mandated nondestructive test method. (Requirement)\n- Administrative/operational point: recurring timing is tied to the issue of a Maintenance Release, so the cadence of inspections depends on operators’ maintenance schedules and the administrative process that issues those releases. (Compliance)\n\nEffects on private choice and market participants\n\n- The measure affects a narrow subset of aircraft owners/operators rather than the wider market for light aircraft. It increases maintenance obligations for those aircraft and therefore raises the marginal operating cost of continued use. (Applicability; Compliance)\n- Independent maintenance providers and certificated mechanics are the actors who will perform the inspections and any repairs; owners may choose different providers or to retire/modify affected aircraft as a cost-management response. (Requirement; Compliance)\n\nSource sections cited:\n- Applicability: identifies covered aircraft (all models with spring-leg MLG and >200 hours service).\n- Requirement: describes the inspection area and focus on weld clusters forward and aft of the MLG leg.\n- Compliance: sets the initial and recurring inspection timing (within 50 hours after 6 Oct 1986; at each new Maintenance Release).\n- Background: records findings of severed and cracked longerons and the hours in service when they were discovered."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standalone Airworthiness Directive with a single, focused purpose: addressing a known structural defect in a specific aircraft type. It has not expanded beyond its original safety intent."},"complexity_factors":["Single, specific aircraft type (Pitts S-1/S-2 series)","Clear applicability criteria (spring leg MLG + >200 hours TIS)","One primary requirement (visual/physical inspection of specific structural elements)","Simple compliance timeline (50 hours TIS after effective date, then recurring at MR issue)","No defined terms section, no cross-references to other legislation, no conditional exceptions","Background provided is factual and brief (3 sentences)","Total length: approximately 150 words"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of **Pitts S-1 and S-2 series aeroplanes** (a type of aerobatic biplane) to inspect a critical structural part — the **fuselage lower longerons** (the main structural beams running along the bottom of the aircraft body).\n\n**Who it affects:**\nAll Pitts S-1 and S-2 models that have:\n- **Spring leg main landing gear** (a specific type of undercarriage), AND\n- **More than 200 hours of flight time**\n\n**What must be done:**\n- Inspect the lower longerons for **cracks** near where the main landing gear attaches — both left and right sides\n- Pay special attention to the **weld clusters** (the joined metal sections) immediately in front of and behind the landing gear leg\n- First inspection due **within 50 flight hours after 6 October 1986**\n- Repeat this inspection **every time the aircraft gets a new Maintenance Release** (a document certifying the plane is airworthy, typically issued after major servicing)\n\n**Why it matters:**\nAircraft have been found with **completely severed longerons** and cracks appearing after just 200–600 hours of use. This is a serious structural failure that could lead to loss of the aircraft. The directive prevents catastrophic accidents by catching cracks before they cause structural collapse."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pitts-s-2-14-fuselage-lower-longerons","history":"/api/acts/ad-pitts-s-2-14-fuselage-lower-longerons/history","analysis":"/api/acts/ad-pitts-s-2-14-fuselage-lower-longerons/analysis","conflicts":"/api/acts/ad-pitts-s-2-14-fuselage-lower-longerons/conflicts","importantCases":"/api/acts/ad-pitts-s-2-14-fuselage-lower-longerons/important-cases","documents":"/api/acts/ad-pitts-s-2-14-fuselage-lower-longerons/documents"}}