{"id":"F2006B11131","name":"AD/LEARJET/15 - Refrigeration System Condenser Fan - Inspection and Replacement","slug":"ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56811,"registerId":"commonwealth-F2006B11131-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET/15 - Refrigeration System Condenser Fan - Inspection and Replacement","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)  \nGates Learjet 24 & 25 Series Aeroplanes\n\nAD/LEARJET/15 Refrigeration System Condenser\n\nFan \\- Inspection and Replacement\n\n  \n7/77\n\nApplicability: Model 24 with S/Nos. 24-100 to 24-356. Model 25 with S/Nos. 25-002 to 25-253.\n\nAnd any 23/24 or 25 Series Learjet which has had a Condenser Fan changed since 1 July 1977.\n\nRequirement: 1. Inspect the P/No. rubber-stamped on a blade of the refrigeration condenser fan.\n\n2. If the fan bears the P/No. 6608059-3, attach a placard worded as follows to the instrument panel adjacent to the refrigeration system control switch:\n\nWARNING\n\nDO NOT OPERATE REFRIGERATION SYSTEM UNDER ANY CIRCUMSTANCES ON THE GROUND OR IN THE AIR UNTIL FAN HAS BEEN REPLACED.\n\nNote: The correct fans have blades which taper in thickness towards the tip and bear the P/Nos. 6608059-2 or 6608059-4.\n\nor Gates Learjet SB 23/24/25-284.\n\nCompliance: Before further flight after 31 July 1977.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of addressing the faulty condenser fan."},"complexity_factors":["Very short document (under 200 words)","Only 2 main requirements (inspection and conditional placarding/replacement)","Simple conditional logic: IF part number = 6608059-3 THEN action required","Limited applicability: specific aircraft models and serial number ranges","No cross-references to other legislation or regulations (except mention of Civil Aviation Regulations 1998 Part 39)","No defined terms section","Single compliance date with no exceptions or extensions"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority. It applies to specific **Gates Learjet 24 and 25 series aircraft** (certain serial numbers, plus any that had their condenser fan replaced after 1 July 1977).\n\n**What it requires:**\n- **Inspect** the refrigeration system's condenser fan to check its part number\n- **If the fan is part number 6608059-3**, pilots must **install a warning placard** on the instrument panel next to the refrigeration controls. The placard must state that the refrigeration system cannot be used in the air or on the ground until the fan is replaced\n- **Replace the faulty fan** with the correct version (part numbers 6608059-2 or 6608059-4, which have blades that taper toward the tip)\n\n**Why it matters:**\nThe specified fan (P/No. 6608059-3) was apparently defective or unsafe — likely prone to failure that could damage the aircraft or cause in-flight emergencies. The directive forces immediate action: either ground the system with a visible warning, or replace the component.\n\n**Deadline:** Before any further flight after 31 July 1977."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD defines its scope within the instrument: it applies to specified Model 24 and 25 serial numbers and to any 23/24/25 Series Learjet that has had the condenser fan changed since 1 July 1977. The instrument itself does not indicate any amendment or change of scope from an earlier version; the scope is stated explicitly in the Applicability section."},"complexity_factors":["Narrow, specific applicability by aircraft model and serial numbers (Applicability)","Simple, discrete required actions: visual inspection of a stamped part number and a placard attachment, with replacement if a particular P/N is present (Requirement 1–2)","Immediate compliance deadline (before further flight after 31 July 1977) increases operational urgency but does not add procedural layers (Compliance)","Dependence on parts identification by P/N and availability of correct replacement fans introduces practical logistics (Note)","Reference to a service bulletin (Gates Learjet SB 23/24/25-284) for additional technical detail creates a secondary source to consult (Note)"],"plain_english_summary":"This AD requires owners/operators of specified Learjet 24 and 25 (and any 23/24/25 series fitted with a condenser fan since 1 July 1977) to inspect the refrigeration condenser fan P/N stamped on a blade. If it is P/N 6608059-3, attach the required warning placard and replace the fan (with approved P/Ns) before further flight. It grounds affected aircraft until compliance; costs fall to the owner/operator."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement","history":"/api/acts/ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement/history","analysis":"/api/acts/ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement/important-cases","documents":"/api/acts/ad-learjet-15-refrigeration-system-condenser-fan-inspection-and-replacement/documents"}}