{"id":"F2006L00458","name":"AD/HS 125/177 - Hydraulic Over-Temperature Switch Fuse","slug":"ad-hs-125-177-hydraulic-over-temperature-switch-fuse","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":117158,"registerId":"commonwealth-F2006L00458-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"British Aerospace BAe 125 Series Aeropla","sectionType":"division","heading":"British Aerospace BAe 125 Series Aeroplanes","content":"### British Aerospace BAe 125 Series Aeroplanes\n\n| AD/HS 125/177 | Hydraulic Over-Temperature Switch Fuse | 4/2006 DM |\n| ------------- | -------------------------------------- | --------- |\n\n| Applicability: | Raytheon Model Hawker 800XP aeroplanes, serial numbers 258541, 258556, and 258567 through 258713 inclusive.                                                                                                                                                                                                                       |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. If not previously accomplished, carry out a general visual inspection to determine if a 20-amp fuse is installed in the hydraulic over-temperature switch electrical circuit on panel ZK in the rear equipment bay in accordance with the Accomplishment Instructions of Raytheon Service Bulletin SB 24-3724, dated May 2005. |\n|                | 2. If, as a result of Requirement 1 inspection, a 20-amp fuse is installed, replace it with a 3-amp fuse in accordance with the Accomplishment Instructions of the SB 24-3724.                                                                                                                                                    |\n|                | 3. If signs of damage are found contact the Raytheon Aircraft Company for applicable repair actions and carry out the specified repairs.                                                                                                                                                                                          |\n|                | Note: FAA AD 2006-02-03 Amdt 39-14455 refers.                                                                                                                                                                                                                                                                                     |\n| Compliance:    | For Requirement 1 - Within 50 flight hours or 30 days after the effective date of this Directive, whichever occurs first.                                                                                                                                                                                                         |\n|                | For Requirement 2 and 3 - Before further flight after the Requirement 1 inspection.                                                                                                                                                                                                                                               |\n|                | This Airworthiness Directive becomes effective on 24 February 2006.                                                                                                                                                                                                                                                               |\n\n| Background: | This Directive requires an inspection to determine if the correct fuse is installed in the hydraulic over-temperature switch electrical circuit on panel ZK in the rear equipment bay and, if necessary, the replacement of the existing fuse and the repair of any damage. The Directive follows advice from the United Sates Federal Aviation Administration (FAA) regarding a report of the installation of an incorrect fuse in the over- temperature switch electrical circuit during aeroplane maintenance. The Directive is issued to prevent possible heat damage to associated wiring and surrounding equipment, which could result in smoke or fire on the aeroplane, when the incorrectly rated fuse fails to blow. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n6 February 2006","sortOrder":0},{"sectionNumber":"AD/HS 125/177","sectionType":"part","heading":"AD/HS 125/177","content":"## AD/HS 125/177","sortOrder":1},{"sectionNumber":"Hydraulic Over-Temperature Switch Fuse","sectionType":"part","heading":"Hydraulic Over-Temperature Switch Fuse","content":"## Hydraulic Over-Temperature Switch Fuse","sortOrder":2},{"sectionNumber":"4/2006 DM","sectionType":"part","heading":"4/2006 DM","content":"## 4/2006 DM","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific safety defect identified by the FAA. It has not expanded beyond its original purpose of correcting a known maintenance error (wrong fuse installation) on a limited fleet of aircraft."},"complexity_factors":["Single, discrete safety issue addressed (fuse rating)","Only 3 specific serial number ranges affected","Clear, sequential requirements (inspect → replace if needed → repair if damaged)","Simple compliance timeline (50 flight hours/30 days for inspection, immediate for replacement)","No nested definitions or cross-referenced legislative provisions","Single external reference (FAA AD and manufacturer Service Bulletin) for technical instructions","No conditional exceptions or alternative compliance methods"],"plain_english_summary":"This CASA Airworthiness Directive mandates owners/operators of specific Raytheon Hawker 800XP aeroplanes (S/N 258541, 258556, 258567–258713) to inspect for and correct a potential electrical fault: a 20‑amp fuse may have been fitted in the hydraulic over‑temperature switch circuit instead of the required 3‑amp fuse.\n\nIt requires prompt inspection, replacement of any incorrect fuse with a 3‑amp unit, and repair of any heat damage to prevent wiring overheating, smoke, or fire."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The Directive does not broaden the regulated population or alter certification scope. It imposes a targeted maintenance requirement limited to listed serial numbers to correct an incorrect fuse installation (Applicability; Requirement). Compliance timing and repair routing to Raytheon modify operational procedures but do not change the aircraft's operating or certification scope."},"complexity_factors":["Narrow applicability: applies only to Raytheon Model Hawker 800XP aeroplanes, specific serial numbers (Applicability).","Simple technical remedy: visual inspection and fuse replacement from 20‑amp to 3‑amp (Requirement 1 and 2).","Operational scheduling constraint: inspection required within 50 flight hours or 30 days; replacement/repairs before further flight (Compliance).","Variable repair discretion: if damage is found, operator must contact Raytheon for applicable repair actions, introducing potential cost and repair-time variability (Requirement 3).","Cross-reference to FAA action: cites FAA AD 2006-02-03, indicating reliance on related foreign directive for context (Note/Background)."],"plain_english_summary":"This Directive requires operators of specific Raytheon Hawker 800XP aeroplanes (listed serial numbers) to inspect the hydraulic over-temperature switch circuit on panel ZK for a 20‑amp fuse and, if present, replace it with a 3‑amp fuse; any damage must be repaired per Raytheon instructions. Owners/operators pay for the inspection and repairs; approved maintenance organisations decide and perform the work. The inspection must be done within 50 flight hours or 30 days and replacement/repairs must be completed before further flight to prevent wiring heat damage or fire."},"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-hs-125-177-hydraulic-over-temperature-switch-fuse","history":"/api/acts/ad-hs-125-177-hydraulic-over-temperature-switch-fuse/history","analysis":"/api/acts/ad-hs-125-177-hydraulic-over-temperature-switch-fuse/analysis","conflicts":"/api/acts/ad-hs-125-177-hydraulic-over-temperature-switch-fuse/conflicts","importantCases":"/api/acts/ad-hs-125-177-hydraulic-over-temperature-switch-fuse/important-cases","documents":"/api/acts/ad-hs-125-177-hydraulic-over-temperature-switch-fuse/documents"}}