AD 50-09-01

50-09-01 NORTH AMERICAN: Applies to all Army Model BC-1A, AT-6, -6A, -6B, - 6C; Navy SNJ-2, -3 and -4 Aircraft.

To be accomplished prior to original certification.

Inspect the horizontal stabilizer rear spar connection for cracked fittings and the installation of shims as follows:

(1) Remove the fuselage to vertical stabilizer fairing assembly and the rear fairing assemblies at the horizontal stabilizer.

(2) Remove the 1/4-inch bolts which attach the rear spar connection fitting to the spar assembly.

(3) Remove paint from connection fittings and inspect for cracks. Check with a machinist's square or other means to determine if fitting is preset. Replace any cracked or preset fitting and repaint all others. New fittings may be made of 24 ST or X4130 bar stock to the same dimensions as the old fittings.

(4) Inspect the fit between the spar and the sides of the base fitting with a feeler gage. Also inspect the fit between fitting P/N 77-21021 and the spar. If gaps exist, shims are necessary.

(5) Fabricate 24ST shims 3 1/8 inches x 15/16 inch and of necessary thickness, and place on either side of spar flanges maintaining a parallel overall dimension to fit inside of fitting P/N 77-21021 within maximum clearance of 0.010.

(6) Drill holes through the shims to match those in the fitting. Remove all chips and reinstall the various parts.

(North American Service Bulletin dated March 6, 1946, covers this subject also.)

This supersedes AD 45-44-03.