55-25-02 de HAVILLAND: Applies to All Model 104 "Dove" Aircraft.
Compliance required as indicated.
Cases have occurred recently where cracks have been found in the left-hand front fin attachment brackets, P/N 4FS.1749 (Pre. Dove Model 7, "Individual fin attachment and rudder control pulley bracket"), and P/N 4FS.6781 (Dove Mod. 7, "To introduce single casting for front fin attachments and control pulley brackets"). The cracks generally emanate from the top rivet hole in the left row and pass through the flange.
The de Havilland Service strongly recommends inspection of the fin attachment brackets at an early date with which the FAA concurs and considers mandatory.
Inspect both front fin attachment brackets for cracks, using a magnifying glass after removing the paint, as soon as practical, but not later than the next 25 hours operation unless already accomplished, and thereafter at each check II (approximately 100-hour periods). Access can be made by enteringthrough bulkhead No. 5.
Should any cracks be found, install new front fin attachment and pulley brackets, P/N 4FS.9165 L. H. and 4FS.9166 R. H. (Ref. Dove Modification 903) and secure to bulkhead No. 6 using 2BA bolts and nuts or equivalent in the top six holes. Rivets are used in the other positions.
Repetitive inspection may be discontinued when the new front fin attachment and pulley brackets per Modification 903 are installed.
(de Havilland Technical News Sheet CT (104) No. 112, Issue 2, dated September 1, 1954, covers this same subject.)