{"id":"F2006B01986","name":"AD/A320/97 Amdt 1 - Airborne Ground Check Module Modification","slug":"ad-a320-97-amdt-1-airborne-ground-check-module-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41208,"registerId":"commonwealth-F2006B01986-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A320/97 Amdt 1 - Airborne Ground Check Module Modification","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)  \nAirbus Industrie A319, A320 and A321 Series Aeroplanes\n\nAD/A320/97\n\nAmdt 1\n\n  \nAirborne Ground Check Module Modification 12/99\n\nApplicability: All Airbus Industrie model A320 aircraft which do not have Modification 27728 or 27189 embodied.\n\nRequirement: Modify the Airborne Ground Check Module (AGCM) in accordance with the instructions of AIRBUS INDUSTRIE Service Bulletin A320-29-1086.\n\nNote: DGAC AD 98-537-124(B) R1 dated 22 September 1999 refers.\n\nCompliance: Before 31 December 1999.\n\nThis Amendment becomes effective on 2 December 1999.\n\nBackground: During two in-flight events and during one functional check of the AGCM of the Ram Air Turbine, a blockage of the low pressure check valve was observed. Such a blockage could lead to the loss of the blue hydraulic system when using the Ram Air Turbine. This amendment introduces additional applicability criteria.\n\nThe original issue of this Airworthiness Directive became effective on 25 March 1999.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment (Amdt 1) to an existing Airworthiness Directive, but it does not represent scope creep. The amendment merely 'introduces additional applicability criteria' — refining which aircraft are affected rather than expanding the directive's purpose. The original intent was to fix a specific mechanical defect in the AGCM, and this amendment continues that same safety purpose with more precise targeting."},"complexity_factors":["Very short document (approximately 200 words)","Only 1 defined term implicitly referenced (AGCM - explained in context)","Single, clear applicability criterion (aircraft without specific modifications)","Single compliance action (follow Airbus Service Bulletin)","No nested exceptions or conditional logic","No cross-references to other legislation beyond a reference to a French aviation authority document (DGAC AD) for information purposes","Straightforward deadline structure (calendar date)"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). ADs are legally binding instructions that aircraft owners and operators must follow to fix unsafe conditions in aircraft.\n\n**What it does:** This directive orders modifications to a specific piece of equipment called the **Airborne Ground Check Module (AGCM)** on certain Airbus A320 family aircraft. The AGCM is part of the system that controls the **Ram Air Turbine (RAT)** — an emergency backup power source that drops down from the aircraft in flight if the main engines fail.\n\n**The safety problem:** The directive was issued because the low pressure check valve in the AGCM could become blocked. If this happened during an emergency when the crew needed the Ram Air Turbine, the aircraft could lose its \"blue\" hydraulic system — one of three hydraulic systems that control flight surfaces. Losing this system in an already emergency situation creates serious safety risks.\n\n**Who must comply:** All operators of Airbus A320 aircraft that haven't already been modified with either **Modification 27728** or **Modification 27189** (factory updates that fix this problem).\n\n**What must be done:** Aircraft operators must modify the AGCM following the exact instructions in **Airbus Service Bulletin A320-29-1086** — a technical manual from the manufacturer detailing the repair procedure.\n\n**Deadline:** The modification had to be completed before **31 December 1999**.\n\n**Why it matters:** This directive prevents a potentially catastrophic failure chain. In an emergency where main power is lost, pilots rely on the Ram Air Turbine to maintain hydraulic pressure for flight controls. A blocked valve could disable this backup system when it's needed most, potentially leading to loss of aircraft control."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment introduces additional applicability criteria: the AD applies only to A319/A320/A321 aircraft that do not have Modification 27728 or 27189 embodied, thereby altering the scope of the original March 1999 directive."},"complexity_factors":["Narrow, clearly‑defined applicability: only A319/A320/A321 aircraft without Mod 27728 or 27189 (Applicability).","Single mandated technical action: modify the AGCM per Airbus Service Bulletin A320‑29‑1086 (Requirement).","Hard compliance deadline and effective date impose scheduling pressure (Compliance: before 31 December 1999; effective 2 December 1999).","Safety‑critical engineering issue: blockage of a low‑pressure check valve linked to loss of the blue hydraulic system when using the Ram Air Turbine (Background).","Amendment changes scope by adding applicability criteria compared with the original March 1999 AD (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators of Airbus A319/A320/A321 aircraft that do not have Modification 27728 or 27189 to modify the Airborne Ground Check Module (AGCM) following Airbus Service Bulletin A320‑29‑1086 by 31 December 1999 (Requirement; Compliance). CASA issued the AD to address observed blockages of a low‑pressure check valve that could cause loss of the blue hydraulic system when the Ram Air Turbine is used (Background). Operators bear the cost and scheduling burden of the mandated modification."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a320-97-amdt-1-airborne-ground-check-module-modification","history":"/api/acts/ad-a320-97-amdt-1-airborne-ground-check-module-modification/history","analysis":"/api/acts/ad-a320-97-amdt-1-airborne-ground-check-module-modification/analysis","conflicts":"/api/acts/ad-a320-97-amdt-1-airborne-ground-check-module-modification/conflicts","importantCases":"/api/acts/ad-a320-97-amdt-1-airborne-ground-check-module-modification/important-cases","documents":"/api/acts/ad-a320-97-amdt-1-airborne-ground-check-module-modification/documents"}}