Electrical Power - AFM Operating Procedures - Amendment
- Published
- Effective
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Affected operators must revise their Boeing 737-8, 737-9, and 737-8200 airplane flight manuals by February 24, 2026, to incorporate the new and revised non-normal operating procedures related to the BAT BUS SECT 2 circuit breaker trip. Flightcrews should be trained on these updated procedures to manage potential in-flight temperature control failures. Comments on the AD can be submitted until April 10, 2026.
Summary
EASA AD US-2026-04-05 is a final airworthiness directive issued by the FAA addressing electrical power and airplane flight manual (AFM) operating procedures for all Boeing 737-8, 737-9, and 737-8200 models. It responds to in-flight incidents of uncontrollable excessive cabin and flight deck temperatures caused by a tripped circuit breaker in the standby power control unit (SPCU). This directive mandates revisions to the AFM to include specific non-normal checklists for flightcrew to manage this condition.
What changed
This new airworthiness directive introduces a requirement to revise the existing AFM operating procedures to provide flightcrew with specific checklists to follow if the BAT BUS SECT 2 circuit breaker in the SPCU trips. It adds three procedures, including a revised 'Cabin Temperature Hot' procedure, a new procedure for when the BAT BUS SECT 2 circuit breaker trips, and an existing quick reference handbook procedure for pack control. This AD is an interim action pending further rulemaking and potential modifications.
Why it matters
This AD is critical for aviation professionals because it addresses a safety risk where excessive temperatures in the cabin and flight deck could incapacitate flightcrew and passengers, potentially compromising safe flight and landing. Operators and maintenance teams must ensure compliance to prevent in-flight environmental control system failures. The directive also signals forthcoming changes as additional circuit breaker issues are evaluated and manufacturer modifications are developed.
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