56-19-01 de HAVILLAND: Applies to All Model 104 "Dove" Aircraft.
Compliance required as indicated below.
A case has occurred in which the mild steel rivet locking the stud, P/N 4CF.607 to the spindle, P/N 4CF.603ND in the aileron differential pulley assembly has sheared, allowing the spindle to unscrew from the stud to such an extent that it, together with the pulley, was on the point of becoming disengaged from the pulley bracket.
To prevent a recurrence of this defect, compliance with Dove Modification No. 765 (installation of a H.T.S. pin for locking stud on aileron differential pulley spindle) is considered mandatory by the British Air Registration Board in which the FAA concurs. Accordingly, unless already accomplished, Modification No. 765 should be embodied on all Dove aircraft as soon as possible, but not later than October 15, 1956.
(Dove Modification 765 is covered in de Havilland Service Technical News Sheet CT (104) No. 114 dated November 1, 1954.)This supersedes AD 55-02-01.