47-43-03: Seaplane Spreader Struts

47-43-03 CESSNA: (Was mandatory Note 14 of AD-768-5.) Applies Only to 120 and 140 Seaplanes Operated Without Spreader Struts Between Floats. Compliance required prior to January 1, 1948. Due to the independent suspension of the floats, racking loads imposed by rough water operation can cause extensive structural damage. As a result, the following inspections and modifications are necessary: 1. Replace all loose and sheared rivets at the joints between the instrument panel and door posts and between the instrument panel and the fuselage skin with AD-5 rivets. In case of damage to the instrument panel at the sheared rivets, an 0.040-inch 24ST alclad channel, 1-inch wide with 5/8-inch flanges, extending the full length of the rivet pattern should be installed with one flange against and riveted to the skin and with the web picking up the rivets through the door post and panel. 2. Inspect the formed brace channel fittings which attach the front and rear door posts to the rear edge of the fuselage carry through spars for cracks in the flanges. If cracks are found the fitting should be replaced or repaired by stop drilling the crack and installing a flat 0.051-inch 24ST alclad strip, cut to the width and contour of the flange, with two or three AD-4 rivets above and below the crack. 3. Inspect the front carry through spar for cracks, particularly below the inboard bolt hole in the attachment of the door post to the spar. If cracks are found the channel should be replaced. 4. Inspect fuselage fitting, Cessna P/N 0440109, to which rear outboard float brace attaches, for cracks in flange at bolt head and along weld bead. Replace with new fitting if cracked. 5. Inspect fitting at fuselage, Edo P/N 88-S-145, to which front outboard float brace attaches, for cracks in weld at bend in top plate and at inboard end of insert where weld is ground off. If cracked, replace with revised fitting having three welded inserts at bend. 6.Replace inboard float brace struts to which outboard struts attach directly, with struts modified to incorporate a universal joint at the attachment of the outboard struts. 7. Add spreader struts, Edo P/N 88-5-175, and diagonal wires, Edo P/N 92-S-200-4, between the floats. 8. Rivet 0.051-inch 24ST alclad doubler, Cessna P/N 0440113, to the fuselage skin below each door just aft of the main landing gear bulkhead. If the fuselage skin is buckled in this area sufficient 1/4-inch rivets should be added to the standard pattern to remove the buckles. (Cessna Service Letters No. 45 dated July 30, 1947, and No. 47 dated August 15, 1947; Edo Drawing 88-03-00A, change 1, dated May 15, 1947; and Edo Service Bulletin No. 3 dated August 30, 1947, cover this same subject.)