AD 2021-16-15 Prohibits Carriage Of Cargo In The Aft Cargo Compartment When The Airplane Is Dispatched Or Released With Failed Electronic Flow Control

The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-8, 737-9, and 737-8200 (737 MAX) airplanes; and certain Model 737-800 and 737-900ER series airplanes.

This AD was prompted by the determination that the aft cargo compartment fire suppression capability is reduced if the airplane is dispatched or released with failed electronic flow control of air conditioning packs, as is currently allowed by these airplane models' master minimum equipment lists (MMELs). This AD prohibits the carriage of cargo in the aft cargo compartment when the airplane is dispatched or released with failed electronic flow control of air conditioning packs. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective August 9, 2021.

Supplementary Information: The FAA was notified by Boeing in March 2021 of a potential concern that the aft cargo compartment fire suppression capability is reduced on affected airplanes if the airplane is dispatched or released with failed electronic flow control of air conditioning packs, as is currently allowed by the existing FAA-approved MMEL of the affected airplane models. This MMEL allowance can result in the inability to contain a fire in the aft cargo compartment due to increased air leakage that degrades the fire suppression performance. A failed electronic flow control of air conditioning packs would significantly increase the pack airflow and cargo compartment air leakage. In April 2021, Boeing advised the FAA that such increased leakage could result in insufficient  concentration of Halon fire suppressant in the aft cargo compartment, which can result in the inability to contain a fire for the time necessary to divert to a suitable airport.

The FAA is issuing this AD to address failed electronic flow control of air conditioning packs, which can result in an uncontained aft cargo compartment fire due to insufficient cargo fire suppression capability. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov