{"id":"F2021L01225","name":"AD/RAD/92 Amdt 2 Rockwell Collins TDR-94/94D Transponder/Honeywell AZ800/810 Air Data Computer Selected Altitude Data Inputs","slug":"ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":102060,"registerId":"commonwealth-F2021L01225-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Radio Communication (including Emergency","sectionType":"part","heading":"Radio Communication (including Emergency Transmitters and Navigation Equipment)","content":"# Radio Communication (including Emergency Transmitters and Navigation Equipment)\n\n| AD/RAD/92Amdt 2 | Rockwell Collins TDR-94/94D Transponder/Honeywell AZ800/810 Air Data Computer Selected Altitude Data Inputs | 18/2021 |\n| --------------- | ----------------------------------------------------------------------------------------------------------- | ------- |\n\n```html\n

Applicability:

Rockwell Collins Mode S Transponders identified by type and Part Number (P/N) in Table 1 when installed in an aeroplane equipped with Honeywell AZ800 or AZ810 (all part numbers) air data computers (ADC) where the data bus interface between the Honeywell ADC and the Rockwell Collins transponder is providing the Selected Altitude data input to the transponder.

Table 1 - Transponders identified by Type and P/N

Type

P/N (all serial numbers)

TDR-94

622-9352-007, 622-9352-008 and 622-9352-108

TDR-94D

622-9210-007, 622-9210-008 and 622-9210-108

Note 1: These transponder/ADC combinations are known to be installed on, but not limited to, the following aeroplanes:

Manufacturer

Model

Avions de Transport Régional (ATR)

ATR 42 and ATR 72 series

Bombardier (formerly Canadair)

CL-600-2A12 (601 Variant), CL-600-2B16 (601-3A and 601-3R Variants)

de Havilland Canada (DHC)

DHC-8, Series 100, 200 and 300, all models

Dassault Aviation

Mystère-Falcon 900 series

Gulfstream

G-IV

Requirement:

1. Either:

a. Modify the transponder in accordance with the applicable Rockwell Collins Service Bulletin (SB) listed in Table 2 and Table 3.

or

b. Replace the transponder, with a TDR-94 unit identified by P/N
622-9352-309 or -409, or a TDR-94D unit identified by P/N
622-9210-309 or -409, as applicable in accordance with an approved aeroplane modification.

Table 2 - TDR-94 Transponders

Current P/N

New P/N(options)

Rockwell Collins Service Bulletin (SB) instructions to be used for modification

622-9352-007

622-9352-309

TDR-94/94D-34-506506 as in force from time to time.

622-9352-409

TDR-94/94D-34-507506 as in force from time to time.

622-9352-008

622-9352-309

TDR-94/94D-34-505506 as in force from time to time.

622-9352-409

TDR-94/94D-34-507506 as in force from time to time.

622-9352-108

622-9352-409

TDR-94/94D-34-505506 as in force from time to time.

Table 3 - TDR-94D Transponders

Current P/N

New P/N (options)

Rockwell Collins SB instructions to be used for modification

622-9210-007

622-9210-309

TDR-94/94D-34-506506 as in force from time to time.

622-9210-409

TDR-94/94D-34-507506 as in force from time to time.

622-9210-008

622-9210-309

TDR-94/94D-34-505506 as in force from time to time.

622-9210-409

TDR-94/94D-34-507506 as in force from time to time.

622-9210-108

622-9210-409

TDR-94/94D-34-505506 as in force from time to time.

\n```\n\n```html\n

Note 2: The words “as in force from time to time” require compliance with the most recent version of the referenced document.

2. Disable the Automatic Dependent Surveillance - Broadcast (ADS-B) function on TDR-94 transponders with P/N 622-9352-409 and TDR-94D transponders with P/N 622-9210-409 unless compliance with European Aviation Safety Agency (EASA) Acceptable Means of Compliance (AMC) 20-24 as in force from time to time or EASA Certification Specifications and Acceptable Means of Compliance for Airborne Communications, Navigation and Surveillance (CS-ACNS) as in force from time to time or United States of America Federal Aviation Administration (FAA) Code of Federal Regulations (CFR) 14CFR91.225 and 91.227 as in force from time to time has been demonstrated.

3. Transponders, identified by the Applicability Statement may not be installed in an aeroplane equipped with Honeywell AZ800 or AZ810 (all part numbers) ADC where the data bus interface between the Honeywell ADC and the transponder is providing the Selected Altitude data input to the transponder unless modified in accordance with Requirement 1.a.

Note 3: This Directive is not applicable to Avions de Transport Régional ATR-42 and ATR-72 aeroplanes on which the affected transponder and ADC installation has been done in accordance with an ATR design definition, although equipped with transponders and Honeywell AZ800 or AZ810 ADC as listed in the Applicability section of this Directive, since on these aeroplanes’ original architecture, the Selected Altitude is not provided by the ADC.

Note 4: This Directive is not applicable to de Havilland Canada DHC-8 Series 100, 200 and 300 aeroplanes, all models, on which the affected transponder and ADC installation has been done in accordance with the applicable de Havilland Canada Type Design definition, although equipped with affected transponders and Honeywell AZ800 or AZ810 ADC as listed in the Applicability section of this Directive, are exempt from having to meet the requirements of this Directive, since on these aeroplanes’ original architecture, the Selected Altitude is not provided by the ADC. This exemption does not apply to aeroplanes that have been modified to enable a digital link between the air data computer and the transponder.

Note 5: EASA AD 2009-0173R1 is the basis for this AD.

Compliance:

For Requirement 1 - Within 60 days after the commencement date of this AD, unless previously accomplished in accordance with a previous issue of this AD.

For Requirement 2 - Concurrent with the accomplishment of the Requirement 1 modification of the aeroplane.

For Requirement 3 - After the commencement date of this AD.

Commencement:

This AD commences on 10 September 2021.

Background:

The original issue of this Directive advised of a mismatch between the ARINC (formerly Aeronautical Radio Inc.) and General Aviation Manufacturers Association (GAMA) specifications for the Selected Altitude in Motion Bit of label 102 in certain Rockwell Collins TDR-94 transponders is causing incorrect transmission of the Mode-S Selected Altitude parameter.

This condition, if not corrected, could lead to invalid Selected Altitude data being transmitted to Mode S ground stations, creating disruptions in the Air Traffic Management process and potentially compromising aeroplane safety.

For the reasons described above, the original issue of this Directive required the modification or replacement of the affected transponders and prohibited reinstallation of unmodified units.

Amendment 1 of this AD continued those requirements and at the same time supplied relief from those requirements for operators of some DHC-8 aircraft.

Amendment 2 of this AD removes obsolete references and makes minor editorial changes to reflect current requirements.

\n```\n\n![Text\nDescription automatically generated](image.001.jpeg)\n\nDavid Punshon \nDelegate of the Civil Aviation Safety Authority\n\n27 August 2021","sortOrder":0},{"sectionNumber":"AD/RAD/92Amdt 2","sectionType":"part","heading":"AD/RAD/92Amdt 2","content":"## AD/RAD/92 \nAmdt 2","sortOrder":1},{"sectionNumber":"Rockwell Collins TDR-94/94D Transponder/","sectionType":"part","heading":"Rockwell Collins TDR-94/94D Transponder/Honeywell AZ800/810 Air Data Computer Selected Altitude Data Inputs","content":"## Rockwell Collins TDR-94/94D Transponder/Honeywell AZ800/810 Air Data Computer Selected Altitude Data Inputs","sortOrder":2},{"sectionNumber":"18/2021","sectionType":"part","heading":"18/2021","content":"## 18/2021","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":false,"description":"This is Amendment 2 of an existing Airworthiness Directive. The background section confirms the scope has remained consistent: Amendment 1 added exemptions for some DHC-8 aircraft, and Amendment 2 only 'removes obsolete references and makes minor editorial changes to reflect current requirements.' The core safety purpose—fixing the altitude data transmission issue—has not expanded beyond the original technical problem."},"complexity_factors":["Highly technical subject matter involving specific aviation hardware (transponders, air data computers, ARINC/GAMA protocols)","Multiple nested tables mapping current part numbers to new part numbers and corresponding service bulletins (Tables 1, 2, and 3)","Cross-references to external technical documents (Rockwell Collins Service Bulletins TDR-94/94D-34-505 through 507, EASA AMC 20-24, CS-ACNS, FAA 14CFR91.225/227)","Conditional logic with multiple compliance paths (modify OR replace)","Specific exemptions with caveats (Notes 3 and 4 exempt certain aircraft but with conditions)","Temporal compliance requirements (60 days, concurrent with modification, after commencement date)","Version tracking (Amendment 2) with references to previous amendments and their changes","Technical jargon requiring aviation engineering knowledge (Mode S, ADS-B, Selected Altitude in Motion Bit, label 102, data bus interface)"],"plain_english_summary":"This CASA Airworthiness Directive mandates a fix for certain Rockwell Collins TDR-94/TDR-94D transponders that, when paired with Honeywell AZ800/AZ810 air data computers, can transmit incorrect Selected Altitude data. It affects operators of listed transponder part numbers on types like ATR, Bombardier CL-600, Dash 8, Falcon 900, and Gulfstream G‑IV.\n\nWithin 60 days operators must modify or replace affected transponders (or fit -309/-409 variants); -409 ADS‑B must be disabled unless specific standards are met. Exemptions apply to some factory ATR/Dash 8 installations."},"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":6,"scope_assessment":{"changed":false,"description":"Amendment 2 makes editorial updates and removes obsolete references but preserves the original safety remit: require modification or replacement of affected transponders (and prevent reinstallation of unmodified units). Amendment 1 previously provided relief for some DHC‑8 aircraft; Amendment 2 does not materially change who is subject to the core requirements."},"complexity_factors":["Detailed technical applicability using multiple specific transponder part numbers and models (Tables 1–3) requiring precise inventory checks.","Two compliance routes: modify per Rockwell Collins Service Bulletins or replace with specified P/Ns, creating choice and implementation variance.","Conditional ADS‑B disablement for particular P/Ns unless compliance with EASA AMC 20‑24/CS‑ACNS or FAA 14 CFR 91.225/91.227 is demonstrated (cross‑jurisdictional certification dependency).","Exemptions for certain aircraft (ATR series; some DHC‑8 installations) based on original architecture, with exemptions voided if a digital link has been added — adds inspection and records complexity.","Time‑bounded compliance (modification within 60 days; ADS‑B action concurrent with modification) imposes scheduling and operational downtime pressure.","References to documents “as in force from time to time” (most recent SBs/standards) create ongoing document‑tracking and version‑compliance tasks.","Prohibition on reinstalling unmodified units after the commencement date increases lifecycle and supply‑chain constraints for operators.","Requirement that replacements/modifications be done in accordance with an approved aeroplane modification increases administrative and approval burdens."],"plain_english_summary":"This airworthiness directive requires operators to either modify or replace specified Rockwell Collins TDR‑94 and TDR‑94D transponders when they receive Selected Altitude data from Honeywell AZ800/AZ810 air data computers, or to disable ADS‑B on certain part numbers unless international certification criteria are met. It affects aircraft owners/operators with those transponder/ADC combinations because incorrect Selected Altitude transmissions can be sent to Mode S ground stations, which the directive says may disrupt air traffic management and affect safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec","history":"/api/acts/ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec/history","analysis":"/api/acts/ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec/analysis","conflicts":"/api/acts/ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec/conflicts","importantCases":"/api/acts/ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec/important-cases","documents":"/api/acts/ad-rad-92-amdt-2-rockwell-collins-tdr-94-94d-transponder-honeywell-az800-810-air-data-computer-selec/documents"}}