58-25-04 HELIO: Applies to Models H-391B and H-395 Aircraft Incorporating Three Fin Hinge Attachments.
Compliance required not later than next 100 hours operation or March 31, 1959, whichever occurs first.
Failure of the fin upper hinge attachment has been reported. Accordingly, the following inspection and replacement programs are required:
Inspect the fin top hinge and attachment details. Cracked parts must be replaced; uncracked parts may be reinstalled. In any case, new reinforcement gussets (P/N 391-022-001-16) must be installed.
(Helio Service Bulletin No. 18 covers this subject.)