EASA SIB 2008-27
FAA SAIB NM-08-15 - Embraer EMB-135 and EMB-145 Aeroplanes - Water Contamination of AHRS Computers
Summary
FAA SAIB NM-08-15 is a Special Airworthiness Information Bulletin addressing water contamination issues in the Attitude Heading Reference System (AHRS) computers installed on Embraer EMB-135 and EMB-145 series aircraft. The bulletin informs operators and maintenance personnel about reported service difficulties due to water condensation causing corrosion and potential failures in AHRS units. It references Embraer Service Bulletins 145-21-0036 and 145LEG-21-0006 for mitigation measures.
What Changed
This bulletin introduces awareness of water contamination risks affecting AHRS computers on Embraer EMB-135 and EMB-145 airplanes and recommends installing FAA-approved protective shields to prevent water ingress. It highlights the existing Embraer service bulletins that provide instructions for installing these protective devices. The bulletin does not mandate compliance but strongly recommends preventive actions to reduce the likelihood of AHRS failures.
Why It Matters
Water contamination of AHRS computers can lead to loss of critical attitude and heading information, impacting flight safety. For operators and maintenance organizations, understanding this risk is essential to maintain aircraft reliability and ensure continued safe operation. The bulletin helps compliance teams prioritize inspections and modifications to mitigate potential dual AHRS failures, which, although rare, could compromise flight instrumentation redundancy.
What To Do
Operators of Embraer EMB-135 and EMB-145 aircraft should review the FAA SAIB NM-08-15 and consider installing the FAA-approved protective shield assemblies as described in Embraer Service Bulletins 145-21-0036 Revision 03 and 145LEG-21-0006 Revision 01. They should also report any AHRS failures to their National Aviation Authority. Coordination with local FAA offices or equivalent authorities is advised for approval if operators develop alternative protective devices.
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