57-24-01 WRIGHT: Applies to All TC18DA and TC18EA Series Engines.
Compliance required at next overhaul but not later than July 31, 1958.
To improve the durability of the impeller drive gear assemblies of the subject engines, intermediate impeller drive gear P/N 145316 must be replaced with P/N 138464 gear, or any gear approved after December 1, 1957.