46-06-01 RYAN: (Was Service Note 5 of AD-749-1.) Applies Only to Model ST-3KR Aircraft Serial Numbers 1001 to 2249, Inclusive.
At each periodic inspection examine the front fin spar at its attachment to the fuselage for cracks. If no cracks are found and if spar has been reinforced at the critical section by means of a wood plug pressed into the end of the spar, no further action is mandatory. If cracks are found, the spar should be repaired by cutting the spar member approximately 3 1/4 inches above the lower bend and splicing on, by means of 3/16-inch bolts, a 1 1/8 by 0.058 inch X-4130 spar replacement section.
(Ryan Service Bulletin No. 1044 covers the installation of the wood plug and Ryan drawing SK-1879 covers the splice repair.)