EASA SIB CE-09-32
Navigation: Cirrus Aircraft Under-Glareshield GPS/WAAS Antenna Mount
Summary
The Special Airworthiness Information Bulletin Navigation: Cirrus Aircraft Under-Glareshield GPS/WAAS Antenna Mount is an FAA informational bulletin addressing airworthiness concerns for Cirrus Models SR20 and SR22 airplanes equipped with GPS/WAAS antennas mounted under the glareshield. It highlights potential issues with antenna mounting robustness and signal loss due to airframe shadowing that may affect GPS/WAAS navigation service. The bulletin applies specifically to Cirrus aircraft using the original under-glareshield mounting location for GPS/WAAS antennas.
What Changed
This bulletin introduces awareness of potential loss of GPS/WAAS navigation service caused by the under-glareshield mounting method originally designed for non-WAAS antennas. It identifies two main concerns: the possibility of antenna detachment due to the 3M Dual Lock fastener system and signal attenuation from airframe shadowing affecting Localizer Performance with Vertical Guidance (LPV) operations. The bulletin recommends relocating antennas to upper fuselage external locations as per Cirrus Optional Service Bulletins.
Why It Matters
This information is important for aviation professionals because loss of GPS/WAAS navigation capability can compromise instrument approach procedures, especially LPV approaches, requiring reliance on less capable navigation systems. Operators and maintenance personnel need to ensure antenna mounting integrity and optimal signal reception to maintain navigation reliability and safety. Understanding these concerns helps prevent unexpected navigation outages and supports compliance with best practices.
What To Do
Owners and operators of Cirrus SR20 and SR22 airplanes with under-glareshield GPS/WAAS antennas should relocate the antennas to upper fuselage external locations following Cirrus Optional Service Bulletins SB 2X-34-23 R1 or SB 2X-34-24 R1. This relocation enhances mounting robustness and maximizes GPS/WAAS signal reception for improved navigation service availability. Stakeholders can obtain the service bulletins from Cirrus Design Corporation or their official website. No mandatory compliance deadline is specified.
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