53-08-01 NAVION: Applies to All Models Except Those Incorporating Palo Alto Airport Co. or Symon Engineering Co. Horizontal Stabilizer Modifications.
Compliance required by June 15, 1953, or next 100-hour inspection, whichever is first.
Inspect both 145-21404-1 and -2 front fittings on the horizontal stabilizer for proper rivet edge distance. If the entire outboard edge of the steel fitting extends past the outboard edge of the butt rib, no further action is required. On the other hand, if the edge of the fitting disappears behind the rib, it will be necessary to ascertain that at least 1/16 inch of material (steel fitting) extends beyond the edge of all rivet holes. Whenever the edge distance is found to be less than 1/16 inch, a new fitting should be installed with proper edge distance.
(A method of conducting the above inspection is described in Ryan Field Service Bulletin No. 19, dated February 16, 1953, which covers this same subject.)