{"id":"F2006B06822","name":"AD/SD3-30/20 - Landing Gear Warning Horn","slug":"ad-sd3-30-20-landing-gear-warning-horn","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114686,"registerId":"commonwealth-F2006B06822-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SD3-30/20 - Landing Gear Warning Horn","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)  \nShort SD3-30 Series Aeroplanes\n\nAD/SD3-30/20 Landing Gear Warning Horn 12/86\n\nApplicability: All models SD3-30 with S/Nos. SH3002 through SH3107 and SH3109 through SH3120.\n\nRequirement: 1. Upon replacement of Lucas Horn P/No. V.0603L with Keystone Horn P/No.\n\nAC155F, relocate mounting of horn according to the requirements of Shorts SD3- 30 Service Bulletin SD330-32-114.\n\n2. For aeroplanes previously fitted with Keystone Horn P/No. AC155F, relocate mounting of horn according to the requirements of the document referenced in Para 1 above.\n\nCompliance: For Para 1: Upon replacement.\n\nFor Para 2: Within 30 hours time in service after 31 January 1987.\n\nBackground: Reports have been received that the Keystone P/No. AC155F landing gear warning horn is inaudible when located between station 3 and 13.45 on the aircraft top centre line.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's scope is limited to specified SD3-30 serial numbers and to the installation or presence of a specified horn part (Keystone P/No. AC155F) relative to a Lucas horn (Applicability; Requirement). It requires relocation per a named service bulletin and sets a compliance timing for already-fitted units (Requirement; Compliance). The AD does not expand obligations beyond those conditional actions and affected serial numbers stated in the source."},"complexity_factors":["Narrow applicability: specific aircraft serial number ranges reduce population affected (Applicability).","Action targets specific part numbers (Lucas P/No. V.0603L and Keystone P/No. AC155F), requiring accurate part identification (Requirement).","Compliance depends on following an external technical document (Shorts SD3-30 Service Bulletin SD330-32-114), introducing reliance on that bulletin's clarity and availability (Requirement).","Two conditional triggers: (a) upon replacement event; (b) for pre-existing installations, a short time-in-service deadline (30 hours after specified date) creates administrative tracking (Requirement; Compliance).","Operational implementation may require certified maintenance labour and aircraft downtime, creating a small practical burden on operators (Requirement; Service Bulletin referenced)."],"plain_english_summary":"This AD requires operators of specified Short SD3-30 serial numbers to relocate a Keystone landing‑gear warning horn (P/No. AC155F) to a different mounting per Shorts Service Bulletin SD330‑32‑114 because the horn can be inaudible when mounted on the top centre line between certain station positions. \n\nCompliance is mandatory under CASA Part 39; affected owners/operators must perform and fund the relocation (or do so within the stated TIS window if already fitted)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, targeted airworthiness directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (under 200 words)","Only 2 defined part numbers (Lucas Horn P/No. V.0603L and Keystone Horn P/No. AC155F)","Single cross-reference to one external document (Shorts SD3-30 Service Bulletin SD330-32-114)","Simple conditional structure: two scenarios (new installation vs. existing installation) with clear compliance timelines","No nested exceptions or complex definitional sections","Narrow applicability (specific aircraft serial numbers only)"],"plain_english_summary":"This is a **safety directive for specific aircraft** — the Short SD3-30 series aeroplanes (a type of small regional turboprop plane). It requires owners and operators to **move the landing gear warning horn** to a different location on the aircraft.\n\n**What the problem is:**\nThe original warning horn (made by Lucas) is being replaced with a different model (made by Keystone, part number AC155F). When this Keystone horn is installed in its original position — between certain points on the top centre line of the aircraft — **pilots can't hear it**. That's dangerous because the horn warns pilots if the landing gear isn't properly deployed for landing.\n\n**Who must do what:**\n- **For planes getting the new horn:** Move the horn to the correct position immediately when you install it.\n- **For planes that already have the Keystone horn installed:** Move the horn within 30 hours of flying time after 31 January 1987.\n\n**Why it matters:**\nAn inaudible warning horn means pilots might not realise their landing gear isn't down, risking a **gear-up landing** — a serious accident where the plane lands on its belly instead of its wheels."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sd3-30-20-landing-gear-warning-horn","history":"/api/acts/ad-sd3-30-20-landing-gear-warning-horn/history","analysis":"/api/acts/ad-sd3-30-20-landing-gear-warning-horn/analysis","conflicts":"/api/acts/ad-sd3-30-20-landing-gear-warning-horn/conflicts","importantCases":"/api/acts/ad-sd3-30-20-landing-gear-warning-horn/important-cases","documents":"/api/acts/ad-sd3-30-20-landing-gear-warning-horn/documents"}}