Four years after investigators recommended that the FAA and Boeing develop retrofits for nacelles on older 737s, the agency has finally signed off on a plan that calls for the work to be done by August 2028. Boeing will start by finalizing service bulletins detailing the modification work by the end of 2024. Operators will then have until July 31, 2028—or another 43 months—to retrofit their fleets. The FAA confirmed its approval in an exemption granted to Boeing in early September. The formal exemption process was necessary to allow Boeing to introduce the series of changes incrementally, instead of having the entire redesign approved as a system before retrofits begin. This would put the individual modifications into the fleet more quickly, Boeing reasoned in its exemption request; the FAA agreed. Boeing 's 737 Next Generation (NG) nacelle redesign focuses on three main areas: new inlet spacers and fasteners, a fan cowl support beam, and a stiffer exhaust nozzle.