{"id":"F2010L01095","name":"AD/RAD/91 Amdt 1 - Rockwell Collins TDR-94/94D Transponder - Air/Ground Discrete Inputs","slug":"ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":83276,"registerId":"commonwealth-F2010L01095-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Radio Communication and Navigation Equip","sectionType":"division","heading":"Radio Communication and Navigation Equipment","content":"### Radio Communication and Navigation Equipment\n\n| AD/RAD/91 Amdt 1 | Rockwell Collins TDR-94/94DTransponder - Air/Ground Discrete Inputs | 8/2010 |\n| ---------------- | ------------------------------------------------------------------- | ------ |\n\n```html\n

Applicability:

Rockwell Collins Mode S Transponders identified by type and Part Number (P/N) in Table 1.

Table 1

Type

P/N (all serial numbers)

TDR-94

622-9352-004, 622-9352-005, 622-9352-006, 622-9352-007, 622-9352-008, 622-9352-108, 622-9352-207, 622-9352-308 and 622-9352-408

TDR-94D

622-9210-004, 622-9210-005, 622-9210-006, 622-9210-007, 622-9210-008, 622-9210-108, 622-9210-207, 622-9210-308 and 622-9210-408

Note 1: These transponders are known to be installed on, but not limited to, the following aircraft models:

Manufacturer

Model

Avions de Transport Régional

ATR 42 and ATR 72, all models

Bombardier (formerly Canadair)

CL-600-1A11, CL-600-2A12 (601 Variant),
CL-600-2B16 (601-3A, 601-3R and 604 Variants), CL-600-2B19, CL-600-2C10, CL-600-2D15 and CL-600-2D24

Bombardier (formerly de Havilland Canada)

DHC-8, all models

Dassault Aviation

Mystère-Falcon 50 (including EX variant), Mystère-Falcon 900, Falcon 900EX, Falcon 2000 and Falcon 2000EX

Gulfstream

G-IV

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

Hawker Beechcraft (formerly Raytheon, Beech)

200 and 400 series, all models

SAAB

SF340A and 340B

Sikorsky Aircraft Corporation

S-92

Requirement:

1. For all affected aeroplanes (ie fixed wing) - If not previously accomplished in accordance with the original issue of this directive, verify that the transponder Air/Ground discrete input connections are installed in accordance with Table 1 of Rockwell Collins Service Information Letter TDR-94( ) SIL 07-1 dated
25 May 2007 (document reference 523-0809129-001000). If the wiring installation is not compliant with the information provided in Table 1 of the SIL, modify the aeroplane Air/Ground discrete input connections in accordance with approved aeroplane modification instructions.

Note 2: This Amendment is not applicable to aeroplanes that have complied with the following Service Bulletins (SB) or have had the following modifications embodied:

a. ATR aeroplanes modified in accordance with ATR (SB ATR42-34-0164 or SB ATR72-34-1093 (modification n° 05602), as applicable to aeroplane model, including those ATR aeroplanes on which modification n° 05602 was incorporated during production.

b. Bombardier CL-600-2B19 aeroplanes if modified in accordance with Bombardier SB 601R-34-146.

c. Bombardier DHC-8-100/200/300 series aeroplane if modified in accordance with MODSUM IS8Q2450012.

d. Dassault aeroplanes modified in accordance with Dassault Aviation SB
F50-457 (modifications M2966 and M2968), SB F50-469 (modification M2998), SB F900-354 (modification M3896), SB F900-368 (modification M5013), SB F900EX-239 (modification M3896), SB F900EX-270 (modification M5013), F2000-312 (modifications M2624 and M2632),
SB F2000-327 (modification M2468), SB F2000EX-043 (modification M2624) or SB F2000EX-084 (modification M2468).

2. For all affected helicopters - Verify that the transponder Air/Ground discrete input connections are installed in accordance with Table 1 of Rockwell Collins Service Information Letter TDR-94( ) SIL 07-1 dated 25 May 2007 (document reference 523-0809129-001000). If the wiring installation is not compliant with the information provided in Table 1 of the SIL, modify the aeroplane Air/Ground discrete input connections in accordance with approved aeroplane modification instructions.

\n```\n\n| | Note 3: EASA AD 2010-0067 refers. |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirement 1 - Before 26 March 2011. |\n| | For Requirement 2 - Within 12 months after the effective date of this Amendment. |\n| | This Amendment becomes effective on 10 May 2010. |\n| Background: | Airservices Australia, the Australian Air Navigation Service Provider (ANSP) together with other national ANSPs, have implemented Advanced Surface Movement Guidance & Control Systems (A-SMGCS) to improve the surveillance and control of on-ground aeroplanes and vehicles, providing conflict detection and alerting on runways. |\n| | In order to ensure proper and effective operation of the A-SMGCS, transponder replies to Air Traffic Control Radar Beacon System (ATCRBS) and All-Call interrogations must be inhibited when the aeroplane is on ground. |\n| | Rockwell Collins TDR-94 and TDR-94D Mode S Transponders have two Air/Ground Discrete inputs that may be connected to the aeroplane Weight-On-Wheels system. A connection to the Air/Ground #2 discrete will implement an inhibition of ATCRBS, ATCRBS/Mode-S All-Call and Mode-S Only All-Call replies when the aeroplane is on the ground. No on-ground reply inhibition occurs if the connection is to the Air/Ground #1 discrete. |\n| | An aeroplane with this transponder interface problem, if not corrected, does not meet the specifications of International Civil Aviation Organisation (ICAO) Annex 10 to the Convention on International Civil Aviation Volume IV Amendment 77 Section 3.1.2.10.3.10 - Inhibition of replies which would lead to degradation of the functioning of the A-SMGCS, could affect the ATC functions in tower, approach and en-route sectors, increase the risk of undetected runway incursions and endangering the aeroplane, its occupants and persons on the ground. |\n| | For these reasons, the original issue of this Directive required a check of the transponder Air/Ground discrete input connections and, in case of discrepancies, the accomplishment of corrective action. |\n| | Since the original issue of this Directive was issued, the European Aviation Safety Agency (EASA) has advised that the Applicability of EASA AD 2009-0097 only referred to ‘aeroplanes’ in which the affected transponders could be installed, inadvertently implying that no helicopters could be affected. Some helicopters (eg Sikorsky S-92) are also known to be equipped with the affected transponders and it has been determined that the unsafe condition addressed by that AD can also occur during taxiing (weight-on-wheels) of helicopters. |\n\n| | Since the original issue of this Directive reflected the requirements of EASA AD 2009-0097, this Amendment expands the applicability to include helicopters. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| | The original issue of this Directive became effective on 26 March 2010. |\n\n![](image.001.png)\n\nMike Higgins \nDelegate of the Civil Aviation Safety Authority\n\n16 April 2010","sortOrder":0},{"sectionNumber":"AD/RAD/91 Amdt 1","sectionType":"part","heading":"AD/RAD/91 Amdt 1","content":"## AD/RAD/91 Amdt 1","sortOrder":1},{"sectionNumber":"Rockwell Collins TDR-94/94DTransponder -","sectionType":"part","heading":"Rockwell Collins TDR-94/94DTransponder - Air/Ground Discrete Inputs","content":"## Rockwell Collins TDR-94/94D \nTransponder - Air/Ground Discrete Inputs","sortOrder":2},{"sectionNumber":"8/2010","sectionType":"part","heading":"8/2010","content":"## 8/2010","sortOrder":3}],"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"The amendment expands applicability beyond 'aeroplanes' to include helicopters (for example Sikorsky S‑92), because the unsafe condition (incorrect Air/Ground discrete wiring causing lack of on‑ground reply inhibition) can also occur during helicopter weight‑on‑wheels/taxiing. The original directive covered aeroplanes only; this Amendment explicitly adds helicopters and sets corresponding compliance timing."},"complexity_factors":["Applicability keyed to a list of specific transponder part numbers and many aircraft models (Table 1) which requires accurate fleet identification.","Cross‑references to Rockwell Collins Service Information Letter TDR‑94 SIL 07‑1 (Table 1) and multiple manufacturer Service Bulletins for exclusions (identification and technical mapping required).","Different compliance deadlines for aeroplanes and helicopters (timing and recordkeeping implications).","Requirement to implement modifications only via 'approved aeroplane modification instructions' introduces certification/engineering approval steps.","Technical nature of wiring verification/modification (maintenance/avionics skill and potential aircraft downtime).","Regulatory interplay with EASA AD 2009‑0097 / EASA AD 2010‑0067 and ICAO Annex 10 standards, requiring alignment with international standards."],"plain_english_summary":"This directive requires operators to check that Rockwell Collins TDR‑94/TDR‑94D transponder Air/Ground discrete wiring matches Rockwell Collins Service Information Letter SIL 07‑1 (Table 1) and to modify the wiring using approved modification instructions if it does not. It applies to specific transponder P/Ns installed on the listed aircraft types (with some exclusions where SBs/mods already exist). CASA set deadlines (aeroplanes: before 26 Mar 2011; helicopters: within 12 months). Operators pay for inspections and any corrective work to ensure proper ground‑reply inhibition for A‑SMGCS."},"summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This instrument is an amendment that expands the scope of the original AD/RAD/91 to include helicopters, in addition to the aeroplanes already covered."},"complexity_factors":["Amendment to an existing airworthiness directive","Expands applicability from aeroplanes to include helicopters","Involves a specific wiring configuration check against a manufacturer service information letter","Contains exemptions for aircraft already modified via listed service bulletins"],"plain_english_summary":"This amendment expands AD/RAD/91 to cover helicopters as well as aeroplanes fitted with certain Rockwell Collins TDR‑94/TDR‑94D Mode S transponders (e.g., Sikorsky S‑92). It addresses a wiring error that can prevent transponder reply inhibition on the ground, degrading A‑SMGCS and increasing runway‑incursion risk.\n\nOperators must verify the Air/Ground discrete input wiring and modify non‑compliant units per Rockwell Collins instructions within set compliance times (earlier deadline for aeroplanes, 12 months for helicopters); certain manufacturer‑modified aircraft are exempt."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original AD/RAD/91 only applied to aeroplanes (fixed-wing aircraft). This Amendment explicitly expands the scope to include helicopters after EASA determined that the unsafe condition could also occur during helicopter taxiing/weight-on-wheels operations. The Background section notes this was an inadvertent omission in the original EASA AD 2009-0097 that CASA had mirrored."},"complexity_factors":["Multiple nested applicability tables defining specific part numbers and aircraft models","Cross-references to external technical documents (Rockwell Collins Service Information Letter TDR-94 SIL 07-1)","Conditional compliance paths: different deadlines for fixed-wing vs rotary-wing aircraft","Exception clauses (Note 2) listing 4 categories of alternative compliance via specific Service Bulletins from different manufacturers","Technical aviation terminology requiring domain knowledge (Mode S, ATCRBS, A-SMGCS, discrete inputs, Weight-On-Wheels)","Amendment structure requires reading original AD plus this Amendment to understand full requirements"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific aircraft to check and potentially fix a wiring problem in their radio transponders.\n\n**What it does:**\n- Targets **Rockwell Collins TDR-94 and TDR-94D transponders** (specific part numbers listed) installed in certain aircraft\n- Requires verification that the transponder's \"Air/Ground\" wiring is connected to the correct input (Air/Ground #2, not #1)\n- If wired incorrectly, the transponder won't properly stop sending signals when the aircraft is on the ground\n\n**Why it matters:**\n- Modern airports use **A-SMGCS** (Advanced Surface Movement Guidance & Control Systems) — radar systems that track aircraft and vehicles on the ground to prevent runway collisions\n- If transponders keep broadcasting while on the ground, they clutter these systems and can mask real collision risks\n- This creates safety hazards: undetected runway incursions, confused air traffic controllers, and potential accidents\n\n**Who must comply:**\n- Operators of affected aircraft including: ATR 42/72, Bombardier CL-600 and Dash 8 series, Dassault Falcon jets, Gulfstream G-IV, Hawker Beechcraft 200/400 series, Saab 340, and Sikorsky S-92 helicopters\n- **Fixed-wing aircraft:** Must comply by 26 March 2011\n- **Helicopters:** Must comply within 12 months of 10 May 2010 (this Amendment's effective date)\n\n**What's new in this Amendment:**\nThe original directive only covered aeroplanes (fixed-wing aircraft). This Amendment **expands coverage to include helicopters** after discovering the same wiring issue affects them too (particularly the Sikorsky S-92)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs","history":"/api/acts/ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs/history","analysis":"/api/acts/ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs/analysis","conflicts":"/api/acts/ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs/conflicts","importantCases":"/api/acts/ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs/important-cases","documents":"/api/acts/ad-rad-91-amdt-1-rockwell-collins-tdr-94-94d-transponder-air-ground-discrete-inputs/documents"}}