{"id":"F2006B08667","name":"AD/CT4/1 - Fuel Contents Indication","slug":"ad-ct4-1-fuel-contents-indication","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51758,"registerId":"commonwealth-F2006B08667-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CT4/1 - Fuel Contents Indication","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)  \nPacific Aerospace Corporation CT/4 Series Aeroplanes\n\nAD/CT4/1 Fuel Contents Indication 9/99\n\nApplicability: Model CT/4, CT/4A and CT/4B series aeroplanes with Serial Numbers 001 through 077 and 097 through 114 inclusive.\n\nRequirement: 1. Re-calibrate and re-mark the fuel contents indicator in accordance with Pacific Aerospace Corporation (PAC) Service Bulletin PACSB/CT/117 Revision 1 dated 7 December 1998.\n\n2. Install a placard, in accordance with PACSB/CT/117 Revision 1, stating:\n\nWHEN FUEL INDICATOR READS ZERO, FUEL REMAINING IN TANK CANNOT BE SAFELY USED IN FLIGHT\n\nNote: CAA(NZ) AD DCA/CT4/6 refers.\n\nCompliance: 1. Prior to 31 December 1999.\n\n2. Prior to 31 December 1999.\n\nThis Airworthiness Directive becomes effective on 9 September 1999.\n\nBackground: This Directive provides action that ensures that the fuel quantity indicating system only displays useable fuel contents.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument specifies a narrow, technical change for a defined set of aircraft (Applicability) and prescribes two required actions with a compliance deadline (Requirement 1–2; Compliance). The text contains no amendment history or indication that the scope has been altered from an earlier version, so there is no evidence in the provided text that the scope has changed from original intent."},"complexity_factors":["Narrow applicability: specific models and tight serial-number ranges (Applicability).","Single technical procedure referenced externally: compliance depends on following PACSB/CT/117 Revision 1 (Requirement 1).","Two discrete, straightforward actions: recalibration/re-marking of gauge and installation of a placard (Requirement 1–2).","Hard compliance deadline with no alternative means of compliance described in the text (Compliance).","Cross-reference to a foreign regulator’s AD (CAA(NZ) AD DCA/CT4/6) which may require coordination (Requirement 2)."],"plain_english_summary":"Pacific Aerospace CT/4, CT/4A and CT/4B aeroplanes (S/N 001–077 and 097–114) must have their fuel quantity indicators recalibrated and a cockpit placard installed (per PACSB/CT/117 Rev 1) by 31 December 1999. Owners/operators pay and schedule the work. The directive ensures the gauge reads only usable fuel and gives pilots a clear warning when the indicator shows zero, reducing risk of misreading remaining unusable fuel."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific technical issue with fuel indication systems on a narrow range of aircraft. It has not expanded beyond its original purpose of ensuring accurate fuel quantity indication."},"complexity_factors":["Extremely short document (under 200 words)","Only 2 substantive requirements with clear deadlines","Single defined applicability range (specific serial numbers)","No nested exceptions or conditional logic","No cross-references to other legislation (only a reference to a New Zealand equivalent AD and a manufacturer service bulletin)","Straightforward compliance timeline (single fixed date for both requirements)"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's aviation safety regulator (CASA) for specific aircraft.\n\n**What it does:**\n- **Targets:** Pacific Aerospace Corporation CT/4, CT/4A, and CT/4B aircraft with specific serial numbers (001–077 and 097–114).\n- **Requires two actions by 31 December 1999:**\n  1. **Recalibrate and re-mark the fuel gauge** so it only shows fuel that can actually be used in flight (not fuel trapped in pipes or unusable corners of the tank).\n  2. **Install a warning placard** telling pilots that when the gauge hits zero, there's still fuel in the tank but it's not safe to fly with it.\n\n**Why it matters:**\n- Prevents pilots from accidentally running out of usable fuel mid-flight because they thought the gauge showed more than was actually available.\n- Addresses a discrepancy between what the fuel gauge displays and what fuel can reliably reach the engine.\n\n**Key concept:** \"Useable fuel\" — aviation fuel that can actually be pumped to the engine under all flight conditions. Fuel below the pickup point or in awkward tank corners may exist but be unusable, creating a dangerous gap between what the gauge shows and what keeps you flying."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ct4-1-fuel-contents-indication","history":"/api/acts/ad-ct4-1-fuel-contents-indication/history","analysis":"/api/acts/ad-ct4-1-fuel-contents-indication/analysis","conflicts":"/api/acts/ad-ct4-1-fuel-contents-indication/conflicts","importantCases":"/api/acts/ad-ct4-1-fuel-contents-indication/important-cases","documents":"/api/acts/ad-ct4-1-fuel-contents-indication/documents"}}