FAA Restricts 737 MAX Cargo Capacity Under Specific Scenario

Boeing 737 MAX fire suppression system
Credit: Sean Broderick/AWST

WASHINGTON—The FAA is ordering restrictions for Boeing 737 MAX and some 737 Next Generation models that would prohibit carrying freight in the aft cargo compartment if certain systems not critical for flight are malfunctioning.

An immediately effective airworthiness directive (AD) set for publication Aug. 9 will prohibit operators of affected 737s from carrying commercial cargo in the below-deck aft hold if the air-conditioning pack-flow control is not functioning. The change is effective Aug. 19.

The current 737 master minimum equipment lists (MMELs), last updated in April 2021 for the 737 MAX and July 2020 for all other variants, permit dispatch with an “electronic flow-control” issue. 

However, Boeing earlier in 2021 determined the issue could increase air leakage from the aft cargo compartment.  

During an event that triggers the compartment’s automatic fire-suppression system, the added air flow could lead to “insufficient concentration of Halon fire suppressant.” In the case of a fire, the scenario could put the aircraft at risk of reaching an alternate airport, the AD explained.

The only exceptions to the conditional cargo ban are “non-combustible and/or non-flammable empty cargo handling equipment, ballast and/or fly-away kits in the aft cargo compartment,” the FAA said.

Affected aircraft include all 737 MAX variants as well as most 737-800s and -900ERs rolled out starting in 2016. The FAA directive lists 663 affected aircraft on the U.S. registry.

Sean Broderick

Senior Air Transport & Safety Editor Sean Broderick covers aviation safety, MRO, and the airline business from Aviation Week Network's Washington, D.C. office.