48-02-01 BELL: Applies to All 47B Series, Through Serial Number 78.
Compliance required before next 25 hours of operation.
Reinforce the tail rotor drive shaft bearing hangers by riveting reinforcement plates, Bell P/N 47-267-001-152, -153, -154, -155, -156, and -157, to the appropriate hangers with AN 470- AD3-4 rivets.
(Bell Service Bulletin 47C56 dated September 10, 1947, also covers this subject.)