EASA SIB 2012-08
Rockwell Collins TDR-94/TDR-94D Transponders — Erroneous Vertical Rate Information
Summary
EASA Safety Information Bulletin SIB No. 2012-08 addresses an issue with Rockwell Collins TDR-94 and TDR-94D Mode S transponders that transmit erroneous vertical rate information when interfaced with Air Data Computers using ARINC 575 inputs. This affects transponders with specific part numbers installed on various aircraft certificated under FAR, JAR, or CS Parts 23, 25, 27, or 29. The bulletin informs operators about the incorrect processing of vertical rate data which may impact Mode S Enhanced Surveillance capabilities.
What Changed
This bulletin introduces awareness of a known issue where the Rockwell Collins TDR-94/94D transponders transmit incorrect vertical rate values due to the way they process ARINC 575 data from the Air Data Computer. It references specific Rockwell Collins Service Bulletins that provide upgrades to correct this behavior. No mandatory regulatory action or Airworthiness Directive has been issued at this time.
Why It Matters
The erroneous vertical rate information can increase the workload for air traffic controllers relying on SSR Mode S ground interrogators, potentially affecting air traffic management. Aviation professionals, including operators and maintenance organizations, need to be aware of this issue to ensure accurate surveillance data and maintain operational safety. Understanding this helps in planning timely upgrades and avoiding potential surveillance discrepancies.
What To Do
EASA recommends that affected operators coordinate with Rockwell Collins to incorporate the applicable Service Bulletin upgrades for the TDR-94/94D transponders as soon as possible. Although the recommendations are not mandatory, implementing the upgrades at the earliest opportunity will help mitigate the transmission of erroneous vertical rate data. Operators should contact Rockwell Collins or EASA for further information and support.