73-20-05 de HAVILLAND: Model DHC-6. Amdt. 39-1725. Applies to de Havilland Model DHC-6 Twin Otter Floatplanes, all Series, certificated in all categories, equipped with Canadian Aircraft Products Model 12000A or 12000B Floats installed prior to Float Serial No. 71.
1. Compliance is required within the next ten hours in service from the effective date of this Airworthiness Directive, unless already accomplished.
To prevent loosening and subsequent pullout failure of certain float to fuselage bolts, comply with accomplishment instruction of de Havilland Service Bulletin 6/296, Revision A, dated May 11, 1973, or an equivalent alteration approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.
This amendment is effective October 3, 1973.