{"id":"F2006B07238","name":"AD/T-28/1 - Horizontal Tailplane","slug":"ad-t-28-1-horizontal-tailplane","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49100,"registerId":"commonwealth-F2006B07238-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/T-28/1 - Horizontal Tailplane","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)  \nNorth American Aviation T-28 Series Aeroplanes\n\nAD/T-28/1 Horizontal Tailplane 4/96\n\nApplicability: All T-28 series aircraft which do not have tailplane reinforcement TO 1T-28-569 incorporated.\n\nNote: Reinforced tailplanes will have ‘D-10’ marked on the tailplane data plate.\n\nRequirement: 1. Remove the elevator and outboard ends of the horizontal tailplane. Visually inspect the aft face of the forward spar and all ribs between the forward and rear spar for signs of cracks. A flexible borescope may be used to assist access.\n\nInspect both inboard and outboard faces of each rib. Refit or repair all access openings in the tailplane before returning the aircraft to service.\n\n2. Remove fairings, as required, to gain access to the forward horizontal tailplane to fuselage attachment fitting. Visually inspect the attachment fitting for cracks or working rivets. Refit fairings before returning the aircraft to service.\n\nCompliance: 1. Inspect in accordance with Requirements 1 and 2 before 5 hours time in service after 28 March 1996, or before 20 June 1996, whichever occurs first. Re-inspect at intervals not to exceed 50 hours time in service or 1 year, whichever occurs first.\n\nBackground: The Warbirds Maintenance Review Board has received a report of a T-28 aircraft with cracks in the tailplane ribs and forward tailplane attachment fitting. The Board has recommended issue of a Directive to inspect unmodified tailplanes on Australian registered T-28 aircraft for similar cracks.\n\nThe T-28 aircraft has a history of horizontal tailplane failures. Investigation of the failures by the manufacturer has shown that the design standard in use at the time may not meet applied service loads. The manufacturer has recommended that all tailplanes are strengthened to meet a later design standard. When details of the modification are received this Directive may be amended accordingly. It has been reported that the aircraft found with cracks had not been modified.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific structural safety issue on a single aircraft type (T-28). The background section mentions potential future amendments if strengthening modifications become available, but this represents anticipated evolution rather than scope creep."},"complexity_factors":["Single, specific aircraft type (T-28 series) with clear applicability criteria","Only 2 defined inspection requirements with straightforward procedural steps","Simple compliance timeline with clear deadlines (5 hours/20 June 1996) and recurring interval (50 hours/1 year)","Minimal cross-referencing — only references to specific technical modification numbers (TO 1T-28-569) and data plate markings","No nested exceptions or conditional logic — either your aircraft has the reinforcement or it doesn't","Short document (approximately 250 words) with single purpose"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of North American T-28 Trojans without the TO 1T-28-569 (D‑10 marked) reinforcement to inspect the horizontal tailplane for cracks — removing the elevator to examine internal ribs, spars, and attachment points — and to repair if defects are found. \n\nInspections must begin immediately (within 5 flight hours after 28 Mar 1996 or by 20 Jun 1996) and repeat every 50 flight hours or annually. It responds to past tail failures that can cause in‑flight separation."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive stays within the original safety purpose set out in the Background: to find and repair cracks in unmodified T-28 horizontal tailplanes and attachment fittings. It does not expand to other aircraft types or to additional structural elements beyond the tailplane and its forward attachment. The only future-scope clause is a note that the AD may be amended when modification details are supplied; that is an administrative contingent change, not a present expansion of scope."},"complexity_factors":["Single aircraft type (North American T-28 series) with one narrow applicability exception (tailplanes modified per TO 1T-28-569 / marked D-10)","Short, discrete steps for inspections (remove elevator/outboard tailplane sections; inspect specified spar faces and ribs; remove fairings; inspect attachment fitting)","One combined initial compliance window with two conditions (within 5 hours TIS after 28 March 1996 OR before 20 June 1996, whichever is earlier)","Recurring inspection interval with two alternative triggers (every 50 hours TIS OR 1 year, whichever occurs first)","No technical definitions or many cross-references; minimal conditional logic beyond the initial timing and the retrofit exception","Contingent statement that the AD may be amended when modification details are received (future conditionality)"],"plain_english_summary":"**What this directive does**\n\n- This Airworthiness Directive (AD) orders specific inspections of the horizontal tailplane on North American T-28 series aeroplanes that have NOT had a particular strengthening modification (Technical Order 1T-28-569) fitted. Aircraft that have been strengthened will have \"D-10\" on the tailplane data plate and are outside the requirement (see \"Applicability\").\n\n**Who it affects**\n\n- Owners and operators of Australian-registered T-28 aircraft without the TO 1T-28-569 tailplane reinforcement.\n- Maintenance organisations and mechanics who perform the work, and parts suppliers if repairs or strengthening are required.\n\n**What you must do (mechanics of the rule)**\n\n- Requirement 1: Remove the elevator and the outboard end sections of the horizontal tailplane and visually inspect the aft face of the forward spar and every rib between the forward and rear spar for cracks. A flexible borescope may be used to help see into restricted areas. Inspect both the inboard and outboard faces of each rib. Any access openings opened for inspection must be refitted or repaired before the aircraft returns to service.\n\n- Requirement 2: Remove any fairings needed to access the forward horizontal tailplane-to-fuselage attachment fitting. Visually inspect that attachment fitting for cracks or \"working\" (loose/moving) rivets. Refit the fairings before returning the aircraft to service.\n\n- Compliance timing: Carry out the initial inspections either within 5 hours time-in-service after 28 March 1996 or before 20 June 1996 — whichever comes first. After the initial inspection, repeat inspections at intervals not exceeding 50 hours time-in-service or 1 year, whichever occurs first.\n\n**Why it matters (stated purpose and practical implications)**\n\n- Stated purpose: The directive was issued after a report of cracks in the tailplane ribs and the forward tailplane attachment on a T-28; the manufacturer has concluded older tailplane designs may not meet later-applied service loads and recommends strengthening. The AD directs inspections to find cracks before they lead to failure.\n\n- Who pays and who decides: Aircraft owners/operators pay for the inspections, any repairs, downtime and any subsequent retrofit. The Civil Aviation Safety Authority enforces the AD (this is an operator-level mandatory requirement under the AD). Maintenance providers decide how to perform the inspections and repairs to meet the AD.\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: labour to remove elevator/fairings, borescope use or other inspection equipment, possible repairs or rivet replacement, and recurring inspection costs every 50 hours or annually. Aircraft downtime during inspections and repairs is an additional cost.\n\n- Incentive to modify: Operators who fit the strengthening modification (TO 1T-28-569) and obtain the corresponding tailplane data-plate marking (\"D-10\") are outside the applicability of this AD and avoid the recurring inspection requirement. That creates a concentrated incentive for affected owners to pay once for a retrofit to avoid repeated inspection costs.\n\n- Implementation risk: The inspections rely on visual examination (with optional borescope). Detection depends on technician skill and access; hidden cracking could be missed without adequate access or nondestructive testing. Repairs must be completed before returning to service to restore airworthiness.\n\n- Effects on private choice and markets: The AD increases recurring maintenance demand for operators running unmodified T-28s; it also creates billable work for maintenance organisations. The retrofit route shifts costs from recurring inspections to a one-time modification expense.\n\n**Operational note**\n\n- The AD may be amended later when full details of the strengthening modification are provided by the manufacturer (the directive states it may be updated once modification details are received)."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-t-28-1-horizontal-tailplane","history":"/api/acts/ad-t-28-1-horizontal-tailplane/history","analysis":"/api/acts/ad-t-28-1-horizontal-tailplane/analysis","conflicts":"/api/acts/ad-t-28-1-horizontal-tailplane/conflicts","importantCases":"/api/acts/ad-t-28-1-horizontal-tailplane/important-cases","documents":"/api/acts/ad-t-28-1-horizontal-tailplane/documents"}}