59-10-09 PRATT & WHITNEY: Applies to Following Turbo Wasp JT3C-6 Engines: JT3C-6 Engines Prior to Serial Numbers P630735B, Except P630406B Through P630413B, P630607B Through P630609B, P630614B Through P630618B, P630623B Through P630635B, and P630637B. JT3C-6 Engines Prior to Serial Numbers P630742D, Except P629708D, P630612D, P630315D, P630317D, P630319D Through P630325D, P630610D Through P630613D, P630619D Through P630622D, and P630636D.
Compliance required as indicated.
As a result of two third-stage turbine blade failures, it will be necessary to replace by 300 hours' of blade operating time, the P/N 271303 blade prior to change J-3 and P/N 371603 blade prior to change C-3. Third stage turbine blades P/N 271303, change J-3 and P/N 371603, change C-3, or later, do not require this replacement.
(P&W Service Bulletin, Chapter 72-8 dated April 3, 1959, of the Heavy Maintenance Manual, P/N 367069 covers this same subject.)