EASA SIB 2012-15R1
Airbus A318, A319, A320 and A321 aeroplanes — VHF Interference on 135.985 and 135.97 MHz
Summary
EASA Safety Information Bulletin 2012-15R1 addresses VHF radio interference issues on frequencies 135.97 MHz and 135.985 MHz affecting Airbus A318, A319, A320, and A321 aeroplanes. The bulletin informs operators about interference caused by certain Electronic Instrument System 1 Display Units, which generate background noise detectable by flight crews. It provides information on the origin of the interference and references Airbus Service Bulletin A320-31-1105 for corrective actions.
What Changed
This revision of EASA SIB 2012-15 adds a reference to a second affected Display Unit part number related to the VHF interference issue. It updates the information to include reports of interference on additional VHF transceivers beyond VHF1, specifically VHF2 and VHF3, as observed at Zurich airport in 2011. The bulletin clarifies that the safety concern remains classified as minor and does not warrant mandatory Airworthiness Directive action.
Why It Matters
The interference can increase flight crew workload due to background noise on critical communication frequencies, potentially impacting operational safety and efficiency. Operators and maintenance organizations need to be aware that unmodified spare Display Units may still be installed, perpetuating the problem. Understanding this issue helps ensure timely preventive maintenance and communication reliability, especially in areas like Zurich airport where interference has been reported.
What To Do
Operators of Airbus A318, A319, A320, and A321 aeroplanes equipped with Electronic Instrument System 1 Display Units part numbers 3906130302 or 3906130402 and using frequencies 135.97 MHz or 135.985 MHz should consider replacing affected Display Units following Airbus Service Bulletin A320-31-1105. Flight crews should apply the Flight Crew Operating Manual procedure to switch to unaffected VHF transceivers if interference occurs. Any observed interference on VHF1, VHF2, or VHF3 should be reported to Airbus for further assessment.