The Federal Aviation Administration (FAA) has unveiled a new directive aimed at addressing a fresh electrical issue discovered in the Boeing 737-8 and 737-9 MAX aircraft, specifically concerning the Standby Power Control Unit (SPCU).

Despite over a decade of developmental and design efforts, a series of single point failure scenarios continue to emerge, exacerbated by overlooked defects in design and production during both the initial certification and the subsequent 20-month re-evaluation period. Notably, as of January 2024, there have been reports of at least three emergency landings by United Airlines triggered by faulty Engine Anti-Ice (EAI) system warnings.

The Aviation Safety Advocacy Group has expressed strong criticism of the FAA’s recent approval for the continued operation of MAX aircraft amidst unresolved critical safety concerns. These concerns extend beyond the incident involving an Alaska Airlines Flight 1282, where a door plug malfunctioned.

A newly identified fault necessitates modifications to the aircraft’s Standby Power Control Unit (SPCU). This marks the third instance of Boeing identifying significant electrical issues within the SPCU since the aircraft was cleared to fly again following an extensive and rigorous 20-month re-certification process by the FAA, which was initiated in response to two devastating crashes that resulted in the loss of 346 lives.

The chronology of issues related to the Standby Power Control Unit (SPCU) includes the following key events:

• On April 7, 2021, shortly after the 737 MAX was reintroduced into service, the FAA received notification from Boeing about critical design alterations to the P6 panel assemblies, prompting an immediate safety concern. By April 9, 2021, Boeing had advised grounding the affected fleet. Investigations revealed compromised electrical bonding impacting the SPCU and EAI systems, potentially leading to a cascade of critical system failures. (Source: FAA Airworthiness Directive (AD) 2021-09-08, issued on April 30, 2021)
• On August 7, 2023, Boeing alerted the FAA to another serious issue where a loss of electrical grounding through the P6 panel could result in SPCU failure. A design oversight removed a crucial redundant grounding path to the SPCU tray, introducing a critical point of failure with potential for various flight deck issues and loss of functionality.
• By August 10, 2023, the FAA announced an urgent safety concern regarding the EAI system. Operating EAI in dry conditions for extended periods could severely damage the engine inlet cowl due to overheating, particularly given the introduction of a new composite material for the MAX. (Reference: FAA AD 2023-15-05, dated August 10, 2023)
• On February 14, 2024, the FAA proposed an additional AD to address a failure risk within the SPCU that could lead to unreported loss of control and issues with the EAI systems.

The accumulation of Airworthiness Directives, manufacturing defects, safety reports from both the FAA and NASA, requests for engineering exemptions, and reported in-flight incidents highlight a concerning trend of safety risks associated with the 737 MAX aircraft.

The Aviation Safety Advocacy Group is calling on DOT Secretary Buttigieg and FAA Administrator Whitaker to reassess the safety of the 737 MAX fleet, advocating for a halt to their operation until all significant safety concerns are thoroughly addressed.