EASA SIB 2008-84R1
Funkwerk Avionics (formerly Filser Electronic) TRT600 and TRT800 Series Transponders — Intermittent Loss of Detection, Insufficient Mode S Reply.
Summary
EASA Safety Information Bulletin 2008-84R1 addresses intermittent loss of detection and insufficient Mode S replies from Funkwerk Avionics TRT600 and TRT800 Series Transponders, including units formerly manufactured by Filser Electronic. These transponders are installed on various aircraft such as Cessna 150, 172, 182, 210, Diamond DA 20, Mooney M20J, Piper PA-28, and multiple sailplane models. The bulletin highlights issues affecting radar tracking and Mode S interrogation responses in European airspace.
What Changed
The bulletin updates the applicability of EASA Airworthiness Directive 2008-0158 to exclude the TRT800 low power version from the loss of detection issue and mandates a fix (Mod-Index 10) for high power TRT800A and TRT800H transponders under EASA AD 2008-0183. It also informs operators about a second issue involving reduced reply rates to Mode S interrogations, planned for transition in core European airspace starting April 2009, with no mandatory recommendations at this time.
Why It Matters
This information is critical for operators and maintenance organizations to ensure continued compliance with airspace requirements where Mode S transponders are mandatory. The intermittent loss of radar detection can lead to safety risks and operational restrictions, especially as European airspace moves towards pure Mode S interrogation. Understanding these issues helps in planning necessary upgrades and reporting occurrences to maintain safe and efficient operations.
What To Do
Operators of aircraft equipped with Funkwerk TRT600 and TRT800 Series transponders should comply with EASA AD 2008-0158 and AD 2008-0183, including installing the Mod-Index 10 fix for affected high power transponders. They should monitor for any unexpected radar tracking losses and report such events to EASA using Form 44 with detailed flight and transponder information. No immediate mandatory action is required for the reduced reply rate issue, but operators should stay informed about future updates.
AI-generated summary from official EASA source document. Always verify against the original.