{"id":"F2007L00378","name":"AD/CESSNA 750/2 Amdt 1 - Chafing of APU Fuel Tube Assembly","slug":"ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":63405,"registerId":"commonwealth-F2007L00378-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Cessna 750 (Citation X) Series Aeroplane","sectionType":"division","heading":"Cessna 750 (Citation X) Series Aeroplanes","content":"### Cessna 750 (Citation X) Series Aeroplanes\n\n| AD/CESSNA 750/2 Amdt 1 | Chafing of APU Fuel Tube Assembly | 3/2007 |\n| ---------------------- | --------------------------------- | ------ |\n\n| Applicability: | Cessna Model 750 Aircraft, Serial Numbers -0001 through -0256 inclusive. |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Perform a detailed inspection to verify the clearance and detect chafing of one of the Auxiliary Power Unit (APU) fuel tube assemblies in the tail cone area of the airplane due to the interference between the APU fuel tube and elevator flight control cables, hydraulic lines, and high temperature bleed air couplings as per provisions of Cessna Alert Service Letter (ASL) ASL750-49-09 Revision 2, dated 10 March 2005 or later FAA approved revisions.2. If chafing is detected, carry out corrective action per ASL750-49-09 Revision 2 or later FAA approved revisions.3. For airplanes having serial numbers -0001 through -0031 inclusive and -0033 through -0107 inclusive, replace the APU fuel tube in the tail cone area of the airplane with a new fuel tube Part Number 6756605-23, in accordance with Cessna Service Bulletin (SB) 750-49-05 Revision 1, dated 17 January 2000 or later FAA approved revision.Terminating ActionModifying the fuel line by installing new lines, fairleads, and clamping configurations in accordance with the Accomplishment instructions of Cessna SB 750-49-12 Revision 1 dated 3 August 2006 or later FAA approved revision terminates the repetitive inspection requirements of this AD.Note: FAA AD 2006-24-01 Amdt 39-14830 dated 3 November 2006 refers. This AD supersedes AD 2005-09-01. |\n| Compliance: | 1. For aeroplanes with serial numbers -0001 through -0240 inclusive, remains unchanged as within 25 flight hours or 48 days, whichever occurs first, after the 25 May 2005 (the effective date of the original issue of this AD) and then, repetitively at intervals not to exceed 250 flight hours or 3 months whichever occurs first. |\n\n| | For aeroplanes with serial numbers -0241 through -0256 inclusive, before further flight after the effective date of this AD and then repetitively at intervals not to exceed 250 flight hours or 3 months whichever occurs first.2. Before further flight.3. Within 25 flight hours or 48 days, whichever occurs first, after the effective date of this AD, but before carrying out inspection per Requirement 1 of this AD. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| | This Amendment becomes effective on 15 March 2007. |\n| Background: | There have been reports of chafed APU fuel tubes leaking into the tail cone area due to the interference between the fuel tube assembly and elevator flight control cables, hydraulic lines, and high temperature bleed air couplings. It is an area where ignition sources are present and there is no fire detection or extinguishing provisions. This interference and the resultant chafing may cause fuel leak and a fire.The actions specified in this AD address the safety risks associated with fire and resultant loss of aircraft.For certain aircraft serial numbers, this AD also requires replacing the APU fuel line.This Amendment adds additional aircraft serial numbers to the applicability section and introduces a terminating action to the repetitive inspections detailed in this AD. The terminating action involves replacement and modification of the fuel line installation.The original issue of this AD became effective on 25 May 2005. |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n2 February 2007","sortOrder":0},{"sectionNumber":"AD/CESSNA 750/2 Amdt 1","sectionType":"part","heading":"AD/CESSNA 750/2 Amdt 1","content":"## AD/CESSNA 750/2 Amdt 1","sortOrder":1},{"sectionNumber":"Chafing of APU Fuel Tube Assembly","sectionType":"part","heading":"Chafing of APU Fuel Tube Assembly","content":"## Chafing of APU Fuel Tube Assembly","sortOrder":2},{"sectionNumber":"3/2007","sectionType":"part","heading":"3/2007","content":"## 3/2007","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"This amendment expands the applicability to additional serial numbers (now covering -0001 through -0256) and introduces a terminating modification option (replacement/modification of the fuel line per SB 750-49-12) that, if implemented, ends the repetitive inspection requirement (Applicability; Requirement; Background)."},"complexity_factors":["Multiple serial-number groups with different compliance timings and requirements (Applicability; Compliance).","Repetitive inspection schedule with short intervals (250 flight hours or 3 months) and initial compliance windows (Compliance).","References to external manufacturer documents (ASL750-49-09, SB 750-49-05, SB 750-49-12) and FAA ADs; compliance depends on following later FAA-approved revisions (Requirement).","Availability of a terminating action (modification per SB 750-49-12) that changes ongoing obligations (Requirement).","Technical corrective actions include part replacement (PN 6756605-23) and installation/configuration changes, creating parts and workmanship dependencies (Requirement).","Safety-critical consequence (fuel leak and fire risk) increases enforcement and recordkeeping importance (Background).","Supersedes and amends a prior AD, requiring operators to track historical compliance and revised applicability (Background)."],"plain_english_summary":"This AD requires inspections of the APU fuel-tube assembly in the tail cone of Cessna 750 aircraft (serials -0001 to -0256), corrective action if chafing is found, and for certain serials a mandatory replacement or a terminating modification that ends repetitive inspections. It directs compliance with Cessna ASL750-49-09 and specified Service Bulletins.\n\nIt addresses fuel leaks near ignition sources; aircraft operators pay inspection and repair costs, must comply with inspection intervals, and can adopt the terminating modification to remove recurring inspections."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"This Amendment 1 expands the original AD's scope in two ways: (1) it adds aircraft serial numbers -0241 through -0256 to the applicability (originally only -0001 through -0240), and (2) it introduces a terminating action (permanent modification) that did not exist in the original 2005 issue, effectively changing the AD from an open-ended repetitive inspection regime to one with a defined endpoint."},"complexity_factors":["Multiple serial number ranges with different compliance timelines (-0001 to -0240 vs -0241 to -0256)","Nested conditional requirements: different actions for different serial number blocks","Cross-references to four external documents (Cessna ASL750-49-09 Rev 2, SB 750-49-05 Rev 1, SB 750-49-12 Rev 1, and FAA AD 2006-24-01)","Terminating action provision that modifies the ongoing obligation structure","Dual measurement compliance periods (flight hours OR calendar days, whichever comes first)","Amendment structure requiring understanding of what changed from original AD 2005-09-01"],"plain_english_summary":"This AD mandates inspections and corrective action for Cessna 750 Citation X jets (S/N -0001 to -0256) after discovery that an APU fuel tube can chafe against nearby lines and hot ducts, risking fuel leaks into an area without fire detection. Operators must inspect, repair as needed, and for earlier serials replace the tube before inspections; repetitive checks continue until the improved fuel‑line retrofit is installed to eliminate the fire hazard."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly","history":"/api/acts/ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly/history","analysis":"/api/acts/ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly/analysis","conflicts":"/api/acts/ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly/conflicts","importantCases":"/api/acts/ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly/important-cases","documents":"/api/acts/ad-cessna-750-2-amdt-1-chafing-of-apu-fuel-tube-assembly/documents"}}