EASA SIB SAIB-2025-08
Indicating/Recording System - Erroneous Illumination of Cabin Altitude Warning Lights in High Altitude Landing Mode
Summary
The Special Airworthiness Information Bulletin SAIB: 2025-08 is an FAA advisory addressing erroneous illumination of cabin altitude warning lights in high altitude landing mode on Boeing 737-700 and 737-800 series airplanes with specific serial numbers. This bulletin provides information and recommended corrective actions but does not mandate compliance. It highlights issues related to wiring errors in previous Boeing Alert Service Bulletins affecting the cabin altitude warning system.
What Changed
SAIB: 2025-08 informs operators about the erroneous illumination issue caused by incorrect wiring in earlier Boeing Alert Service Bulletin revisions 1 through 3. It recommends corrective actions from Boeing Alert Service Bulletin 737-31A1332 Revision 5 to fix the wiring and prevent false warnings during high altitude landing mode. The bulletin clarifies that this issue does not currently warrant an airworthiness directive under 14 CFR part 39.
Why It Matters
This information is important for aviation professionals because erroneous cabin altitude warnings can lead to unnecessary pilot distractions or misinterpretations during critical flight phases. Operators and maintenance teams need to ensure the cabin altitude warning system functions correctly to maintain situational awareness and flight safety. Understanding the wiring correction helps avoid unnecessary maintenance or operational disruptions.
What To Do
Owners and operators of affected Boeing 737-700 and 737-800 airplanes should perform the wiring corrections specified in steps 34 and 35 of the Work Instructions in Boeing Alert Service Bulletin 737-31A1332 Revision 5 at the earliest opportunity. If the functional test from Revision 4 has already been completed, further action may not be necessary. Contact the FAA or Boeing for additional guidance if needed.