AD FAA-2026-4660

The FAA is superseding Airworthiness Directive (AD) 2026-04- 05, which applied to all The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes. AD 2026-04-05 required revising the existing airplane flight manual (AFM) to provide the flightcrew with operating procedures (non-normal checklists) if a certain circuit breaker in the standby power control unit (SPCU) trips. Since the FAA issued AD 2026- 04-05, the FAA has determined that additional revisions to the AFM are necessary to address certain environmental control system (ECS) circuit breakers downstream of the SPCU that could also trip. This AD retains the requirements of AD 2026-04-05 and requires revising the existing AFM to provide the flightcrew with operating procedures (non-normal checklists) if certain ECS circuit breakers trip. The FAA is issuing this AD to address the unsafe condition on these products.