{"id":"F2006B06512","name":"AD/RAD/58 Amdt 1 - AlliedSignal CAS-81 TCAS II","slug":"ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48099,"registerId":"commonwealth-F2006B06512-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/RAD/58 Amdt 1 - AlliedSignal CAS-81 TCAS II","content":"![](image.001.png)  \nRadio Communication and Navigation Equipment\n\nAD/RAD/58\n\nAmdt 1\n\n  \nAlliedSignal CAS-81 TCAS II 7/98\n\nApplicability: AlliedSignal Commercial Avionics Systems CAS-81 Traffic Alert and Collision Avoidance Systems (TCAS), with serial numbers below 6066.\n\nNote: CAS-81 TCAS II equipments are known to be installed on, but not limited to, the following aircraft series:\n\nAerospatiale ATR-42, ATR-72\n\nAirbus Industries A300, A310, A320, A321, A330 and A340 Beech 1900 and BE-65 through BE-90\n\nBoeing 727, 737, 747, 757, 767 and 777\n\nConvair CV-580\n\nde Havilland DHC-7 and DHC-8\n\nEmbraer EMB-120\n\nFairchild F227\n\nFokker F28 Mk 100, Mk 1000 and Mk 4000\n\nGeneral Dynamics Convair 340 and 440 Gulfstream G-159 and G-IV\n\nLockheed L1011\n\nMcDonnell Douglas DC-8, DC-9, DC-10, MD-11 and MD-80 Rockwell International NA-265-65\n\nSAAB 340\n\nShorts 360\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nRequirement: Amend the Limitations Section of the Aircraft Flight Manual to include the following:\n\n“In order to ensure that the audio output of the CAS-81 TCAS operates properly, accomplish the following:\n\n    Prior to the first flight of the day; prior to the accumulation of 10 hours of uninterrupted power; and at the mid-point of any one flight scheduled to exceed 10 hours: Cycle the power to the TCAS Processor via the circuit breaker or power bus.\n\n    b. Prior to taxi before take-off: Initiate the TCAS functional test in accordance with the procedures in the Aircraft Flight Manual to verify the operational condition of the CAS-81 TCAS.”\n\nAlternately,\n\nIf the aircraft manufacturer has substantiated 30ºC as a maximum ambient for the TCAS processor location amend the Limitations Section of the Aircraft Flight Manual to include the following:\n\n“In order to ensure that the audio output of the CAS-81 TCAS operates properly, accomplish the following:\n\nPrior to each flight of up to 18 hours duration, reset the TCAS circuit breaker and conduct a TCAS self-test.”\n\nNote 1: Applications for an amendment to the Aircraft Flight Manual should be made to the local CASA District Airworthiness Office.\n\nNote 2: Tests may be performed by a flight crew member.\n\nNote 3: Modification of the TAP-81A TCAS processor receiver in accordance with AlliedSignal Service Bulletin TPA-81A-34-82 dated January 1996 or TPA-81A-34-84 dated January 1996 is considered an optional terminating action for the requirement of this Directive. Following incorporation of the modifications the Flight Manual amendment may be removed (see Note 1).\n\nNote 4: FAA AD 95-26-15 R1 Amdt 39-9824 refers.\n\nCompliance: The original compliance of ‘Effective 3 January 1996’ remains unchanged.\n\nThis amendment becomes effective on 18 June 1998.\n\nBackground: The FAA has received reports of failure of the audio output of CAS-81 TCAS. This condition could result in the CAS-81 TCAS failing to perform its collision avoidance function.\n\nThe original issue of this Directive required a revision to the Aircraft Flight Manual to provide the flightcrew with procedures to cycle power to the TCAS processor via the circuit breaker or power bus and to perform a TCAS functional test to verify proper operation of the TCAS.\n\nThis Amendment amends the title of the Directive, identifies the serial number range of the effected equipment and introduces an optional terminating action, whereby the original flight manual amendment may be removed. It also introduces an alternative flight manual amendment, which may be used if the aeroplane manufacturer has substantiated 30º C as a maximum ambient temperature for the TCAS processor location.\n\nThe original issue of this airworthiness directive became effective on 3 January 1996.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment stays within the original scope of addressing CAS-81 TCAS audio failures. It refines and adds options (alternative procedure based on temperature, optional terminating action via hardware modification) but does not expand beyond the original safety purpose of ensuring TCAS audio functionality."},"complexity_factors":["Single, specific technical subject matter (one TCAS model)","Clear applicability criteria (serial numbers below 6066)","Two distinct compliance pathways with straightforward conditions","Limited cross-referencing (only one FAA AD reference)","No nested definitions or interpretation sections","Procedural requirements are step-by-step and operational rather than legalistic","Background section provides clear rationale"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of aircraft fitted with AlliedSignal CAS-81 TCAS units (serial numbers <6066) to add flight‑manual procedures to prevent loss of TCAS audio warnings—either frequent power‑cycling and functional tests or, if the processor location is proven ≤30°C, a less frequent reset-and-self‑test regime. It also allows a permanent hardware modification per AlliedSignal service bulletins to remove the temporary procedures. This addresses the risk of pilots not hearing collision alerts."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment expanded and clarified the original AD. Compared with the original requirement (which required an AFM revision for power-cycling and functional testing), the amendment: identifies the affected equipment by serial number (below 6066); introduces an alternative AFM amendment that applies if the aircraft manufacturer substantiates a 30°C maximum ambient at the TCAS processor location; and adds an optional terminating action — specific AlliedSignal service-bulletin modifications — after which the AFM amendment may be removed. These additions broaden the compliance paths (allowing either operational changes, manufacturer substantiation or hardware modification) and therefore alter the range of choices available to operators compared with the original single-path requirement."},"complexity_factors":["Single-topic airworthiness directive focused on one equipment model and specific serial-number range","Two alternative compliance procedures (regular power-cycle + in-flight check; or reset + self-test if 30°C substantiation provided)","Optional terminating action via incorporation of manufacturer service bulletin (two bulletin references)","Multiple affected aircraft types listed (broad applicability across fleets)","Several administrative cross-references (CASA AFM amendment process, FAA AD reference)","Limited conditional logic (ambient-temperature substantiation required for alternative) but few nested exceptions"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- It requires operators of AlliedSignal CAS-81 TCAS II units (Traffic Alert and Collision Avoidance System), with serial numbers below 6066, to change the Aircraft Flight Manual (AFM) limitations to add procedures that ensure the TCAS audio output works correctly.\n\n- The required procedures are either:  \n  - Cycle the TCAS processor power (via circuit breaker or power bus) before the first flight of the day, before 10 hours of continuous power, and at the mid-point of any flight longer than 10 hours; and run the TCAS functional test before taxi for take-off.  \n  - Or, as an alternative if the aircraft manufacturer can show the TCAS processor location will not exceed 30°C, reset the TCAS circuit breaker and do a self-test before each flight of up to 18 hours.\n\n- As an optional terminating action, fitting the TAP-81A processor receiver modifications described in AlliedSignal Service Bulletin TPA-81A-34-82 or TPA-81A-34-84 (January 1996) lets an operator remove the AFM amendment.\n\n- The AD applies to CAS-81 TCAS II units installed on many airframes (examples listed in the AD include ATR, Airbus A300–A340 families, various Beech, Boeing series, Embraer EMB-120, Fokker, Saab 340, Shorts 360, and others). The AD identifies the affected equipment by serial number (below 6066).\n\n- Compliance timing: the original effective compliance date (3 January 1996) remains; this amendment took effect 18 June 1998. Applications to amend the AFM are handled by the local CASA District Airworthiness Office; flight crew may perform the tests.\n\n**Who this affects**\n\n- Aircraft operators and owners who have AlliedSignal CAS-81 TCAS II units with serial numbers below 6066 installed on their aeroplanes.  \n- Flight crews, who are required to perform the specified power-cycle and functional tests (or the alternate reset/self-test) as part of flight preparation and during long flights.  \n- Maintenance organisations and engineers if they choose to perform the optional hardware modification described in the AlliedSignal service bulletins.\n\n**Why it matters (stated purpose and practical implications)**\n\n- Stated purpose: the FAA received reports that the CAS-81 TCAS audio output has failed in service; without correct audio output the TCAS collision-avoidance function could be degraded. The directive therefore imposes operational checks to reduce the chance of undetected audio failure.\n\n- Practical implications and trade-offs:  \n  - Safety mechanism: the AFM changes make the crew perform repeated power cycles and pre-taxi functional tests to catch audio failures early.  \n  - Operational cost and burden: operators bear the time cost of extra checks (pre-flight and during long flights), potential dispatch delays if a test fails, and possible additional maintenance. For long flights this may require mid-flight actions that interrupt normal crew duties.  \n  - Option to remove ongoing burden: installing the AlliedSignal hardware modification removes the AFM amendment requirement but incurs direct modification cost, downtime, and possibly parts/installation scheduling.  \n  - Manufacturer role and approvals: the alternate, less-frequent procedure is only available if the aircraft manufacturer substantiates a 30°C maximum ambient for the processor location; that requires manufacturer testing or engineering substantiation and CASA acceptance.  \n  - Regulatory process: AFM amendments require CASA approval (local District Airworthiness Office), so there is administrative work and some discretionary review at CASA.\n\n**Who pays, who decides, and what behaviour changes**\n\n- Who pays: the aircraft operator/owner pays the ongoing compliance costs (crew time, potential delays), and pays if choosing the hardware modification (parts, labour, downtime).  \n- Who decides: CASA enforces the AD and approves AFM amendments; the aircraft manufacturer can decide whether to substantiate the 30°C ambient alternative; AlliedSignal provides the service bulletins for the optional terminating modification.  \n- Behaviour changes: flight crews must add power-cycle and functional test steps to pre-flight and in-flight procedures (or the alternate reset/self-test); maintenance may implement the service-bulletin modification to stop the need for those manual checks.\n\n**Implementation and risk considerations**\n\n- Compliance monitoring: CASA administers AFM amendments and could require proof of compliance; operators must document checks and any failures.  \n- Substitution effects: operators may prefer the one-time hardware modification to avoid repeated operational checks, creating demand for parts and approved installers.  \n- Operational risk: required mid-flight power cycles or tests on long sectors are workable but add crew workload and create modest operational friction.  \n- Capture of benefits/costs: the safety benefit (reducing undetected audio failures) is concentrated on passengers and operators; the cost is concentrated on operators (time, maintenance, modification expenses).\n\n(Referenced parts: Requirement and Notes, including Note 3 which identifies AlliedSignal Service Bulletin TPA-81A-34-82 / -84 as the optional terminating action, and the Applicability block identifying serial numbers below 6066 and affected aircraft series.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii","history":"/api/acts/ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii/history","analysis":"/api/acts/ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii/analysis","conflicts":"/api/acts/ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii/conflicts","importantCases":"/api/acts/ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii/important-cases","documents":"/api/acts/ad-rad-58-amdt-1-alliedsignal-cas-81-tcas-ii/documents"}}