{"id":"F2007L01056","name":"AD/DO 228/11 - Honeywell CAS 67A ACAS II - LBA STC SA1310","slug":"ad-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":65007,"registerId":"commonwealth-F2007L01056-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Dornier 228 Series Aeroplanes","sectionType":"division","heading":"Dornier 228 Series Aeroplanes","content":"### Dornier 228 Series Aeroplanes\n\n| AD/DO 228/11 | Honeywell CAS 67A ACAS II - LBA STC SA1310 | 5/2007 |\n| ------------ | ------------------------------------------ | ------ |\n\n| Applicability: | Model 228-100, 228-101, 228-200, 228-201 and 228-212 aeroplanes, all serial numbers except 8191, 8232, 8233, 8244 and 8245, modified in accordance with Luftfahrtbundesamt (LBA) Supplemental Type Certificate (STC) No.SA1310 before 31 January 2005.                                                                                                                                                                                                                                                                                |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Modify the Honeywell CAS67A Airborne Collision Avoidance System (ACAS) II, installed under LBA STC SA1310, in accordance with Aerotechnic Vertriebs und Service GmbH Service Bulletin DO228-119780-0104 Revision 2 dated21 December 2006.                                                                                                                                                                                                                                                                                             |\n|                | Note: EASA AD 2007-0059 refers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| Compliance:    | Within 200 flight cycles or 8 weeks, whichever comes first, after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                                               |\n|                | This Airworthiness Directive becomes effective on 10 May 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Background:    | The European Aviation Safety Agency (EASA) has received advice from the STC holder that in earlier installations of the ACAS II system there were no isolation diodes installed in the heading and attitude valid lines. The absence of an isolation diode in the valid lines can prevent the valid flag to come up even if a gyro fault exists. The problem has only been detected for heading valid lines but could equally affect the attitude valid lines.                                                                        |\n|                | With installation of the ACAS II, the heading and attitude valid lines have to be connected to the TPU67A Processor. On valid state, the signals are +28VDC. On invalid, the signals are open. This condition of direct connection (without an isolation diode installed) of the valid lines to the TPU67A, if not corrected, could cause the TPU67A to feed current into the open stated valid lines. This prevents the flag to appear even if the gyro is invalid, providing the flight crew with erroneous navigation information. |\n\n|     | For the reasons stated above, this Directive requires the installation of isolation diodes into the signal lines to the TPU67A to prevent reverse feed of the valid lines. |\n| --- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n16 March 2007","sortOrder":0},{"sectionNumber":"AD/DO 228/11","sectionType":"part","heading":"AD/DO 228/11","content":"## AD/DO 228/11","sortOrder":1},{"sectionNumber":"Honeywell CAS 67A ACAS II - LBA STC SA13","sectionType":"part","heading":"Honeywell CAS 67A ACAS II - LBA STC SA1310","content":"## Honeywell CAS 67A ACAS II - LBA STC SA1310","sortOrder":2},{"sectionNumber":"5/2007","sectionType":"part","heading":"5/2007","content":"## 5/2007","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It addresses a specific wiring defect in a specific avionics installation on specific aircraft. There is no evidence of scope creep; the directive remains tightly focused on the isolation diode modification."},"complexity_factors":["Highly specific technical scope: applies only to one aircraft type (Dornier 228) with one specific modification (LBA STC SA1310) installed before a cutoff date","Multiple exclusion criteria: five specific serial numbers excluded, plus date-based applicability filter","Single technical requirement with reference to external technical document (Service Bulletin DO228-119780-0104 Rev 2)","Cross-reference to European regulation (EASA AD 2007-0059) for context but not for compliance","No defined terms section, no nested conditional logic, no exceptions to exceptions","Clear compliance deadline with simple alternative calculation (flight cycles OR weeks)"],"plain_english_summary":"This AD requires owners of certain Dornier 228 aircraft fitted under LBA STC SA1310 (before 31 Jan 2005) to install isolation diodes in the Honeywell CAS67A ACAS II wiring. The diodes prevent a wiring fault from hiding warning flags when a gyro is faulty, avoiding pilots flying with incorrect heading/attitude. Compliance: within 200 flight cycles or 8 weeks after 10 May 2007 (some serials excluded)."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD remains narrowly focused on correcting a specific wiring omission in ACAS II installations under LBA STC SA1310. It does not expand obligations beyond installing isolation diodes on the identified aircraft. The directive implements the STC holder's reported fix and does not grow the original purpose into unrelated regulatory requirements."},"complexity_factors":["Short, single-issue directive focused on one hardware fix (isolation diodes).","Clear applicability limited to specific Dornier 228 models and to installations under a single STC (SA1310) with five serial-number exceptions.","Single compliance action referenced to one service bulletin (DO228-119780-0104 Rev 2).","Simple compliance window: 200 flight cycles or 8 weeks, whichever comes first.","Minor cross-reference: notes EASA AD 2007-0059 and the LBA STC; no large network of interdependent provisions or multiple conditional branches."],"plain_english_summary":"**What this directive does (mechanically)**\n\n- This Airworthiness Directive (AD) requires a specific hardware modification to Honeywell CAS67A ACAS II units that were installed under Luftfahrtbundesamt (LBA) Supplemental Type Certificate (STC) SA1310 on certain Dornier 228 aeroplanes.\n- The modification is the installation of isolation diodes in the \"heading valid\" and \"attitude valid\" signal lines to the TPU67A processor. The required work is to be done by following Aerotechnic Vertriebs und Service GmbH Service Bulletin DO228-119780-0104 Revision 2 (dated 21 December 2006). (See \"Requirement\" in the AD.)\n- Compliance deadline: install the diodes within 200 flight cycles or 8 weeks, whichever comes first, from the AD's effective date (the AD became effective 10 May 2007). (See \"Compliance\".)\n\n**Who this affects**\n\n- Aircraft owners/operators of Dornier 228 models 228-100, 228-101, 228-200, 228-201 and 228-212 that have been modified under LBA STC SA1310 prior to 31 January 2005. Five serial numbers are excluded (8191, 8232, 8233, 8244 and 8245). (See \"Applicability\".)\n- Maintenance organisations and technicians who must perform the modification and record compliance.\n- The STC holder and parts suppliers who provide the service instructions and diodes (the AD points to the STC holder's advice and the service bulletin). (See \"Background\" and the service bulletin reference in \"Requirement\".)\n\n**Why it matters (stated purpose and practical effect)**\n\n- The AD is issued because the STC holder reported that earlier installations omitted isolation diodes in the valid (\"valid flag\") lines. Without diodes, the TPU67A processor can back-feed current into an open (invalid) signal line, causing the system to show the navigation \"valid\" flag even when a gyro has failed. (See \"Background\".)\n- Installing isolation diodes prevents reverse current flow and therefore prevents the ACAS II unit from displaying a misleading \"valid\" indication when the underlying gyro is invalid. The AD therefore changes the aircraft's wiring and maintenance requirements to remove this specific failure mode.\n\n**Costs, incentives and trade-offs (practical implementation notes)**\n\n- Who pays: the aircraft owner/operator pays for parts, labour and aircraft downtime required to fit the diodes and carry out testing and paperwork.\n- Who decides: the regulator mandated the action; maintenance providers decide scheduling and perform the work to the service bulletin; the STC holder and parts suppliers decide parts availability and technical details in the service bulletin.\n- Compliance burden: a single hardware change per affected aircraft plus associated inspection and paperwork. The AD prescribes a short compliance window (200 flight cycles or 8 weeks), which concentrates scheduling pressure on operators.\n- Opportunity cost: aircraft may be temporarily unavailable while the modification is performed; operators must prioritise the work ahead of other maintenance to meet the deadline.\n- Implementation risk: low technical complexity (installation of diodes), assuming qualified maintenance personnel and parts are available. Risk rises if parts are scarce or maintenance slots are limited.\n- Effects on private enterprise: small, discrete cost for affected operators; maintenance shops gain short-term work. The AD does not alter operating rules or permissions beyond the mandatory equipment change.\n\n**Other notes**\n\n- The AD cross-references EASA AD 2007-0059 and is based on the STC holder's safety advice. (See \"Note: EASA AD 2007-0059 refers\" and \"Background\".)\n- The problem was observed on heading valid lines but could equally affect attitude valid lines; the AD requires diodes for the relevant lines to address both possibilities.\n\n(References in this summary are to the AD text headings: \"Applicability\", \"Requirement\", \"Compliance\" and \"Background\".)"},"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-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310","history":"/api/acts/ad-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310/history","analysis":"/api/acts/ad-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310/analysis","conflicts":"/api/acts/ad-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310/conflicts","importantCases":"/api/acts/ad-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310/important-cases","documents":"/api/acts/ad-do-228-11-honeywell-cas-67a-acas-ii-lba-stc-sa1310/documents"}}