56-22-02 HELIO: Applies to Model H-391B Aircraft, Serial Numbers 003 to 029 Inclusive.
Compliance required within next 100 hours.
Cases have been reported of finding cracked upper wing attachment thrust washers, P/N HS-15. These are special heat-treated washers installed beneath the head of the bolt attaching the top of the front wing spar to the carry-through structure. Accordingly, these washers must be replaced with new improved type procured from the airplane manufacturer.
(Helio Field Service Bulletin No. 13 dated July 18, 1956, covers this same subject and specifies the bolt torque requirements.)