TELEDYNE CONTINENTAL AIRCRAFT ENGINE …

1 TELEDYNE CONTINENTAL AIRCRAFT ENGINE TELEDYNE INDUSTRIES, INC. 1989 TELEDYNE CONTINENTAL MOTORSA ircraft ProductsPO Box 90 Mobile Alabama 36601 Member of GAMAG eneral AviationManufacturer s Associationservice bulletin10 March 1989 SUBJECT:COMPRESSOR belt SHEAVE ALIGNMENT AND belt TENSIONING MODELSAFFECTED: IO-520-BA, BB; TSIO-520-L, LB, WB, UB, BE; IO-550-BCOMPLIANCE:When a replacement starter drive assembly, idler sheave or compressoris installed or when premature belt replacement is belt replacement on the above engines can usually be attributed to improperalignment of the sheaves and/or improper belt tensioning. The problem of improper alignmentand/or improper belt tensioning can be corrected per the following instructions:1.

2 Place the alignment bar (Borroughs Tool Number 8082) around the driver sheavecausing the extended end to overlay the upper portion of the compressor outer the alignment is correct, the extended end will fall within of the center of thebottom of the sheave groove. If the alignment bar does not fall within of the centerof the bottom of the sheave groove, remove the driver sheave and place as many (up tothe maximum of 5) inch shims, P/N 646064-20, on the starter shaft as are requiredto achieve the correct alignment between the driver sheave and compressor the alignment bar. Lubricate the threads of the 12 point self-locking nut withclean 50 weight ENGINE oil and torque to 450-500 inch pounds and recheck ENGINE from turning during 1:Borroughs Tool 8082 should be checked for flatness prior to each use.

3 This canbe done by laying it on a surface table or similar flat 2:If the driver sheave retaining nut is anything other than a 12 point self-locking nutP/N 649924 it should be replaced and torqued per Paragraph the alignment bar around the idler sheave causing the extended end to overlay thelower portion of the compressor outer sheave. When the aligment is correct theextended end of the alignment bar will fall within inch of the center of the bottom ofthe sheave groove. If the alignment bar does not fall within inch of the center ofthe bottom of the sheave groove, remove the idler sheave and place as many (up tomaximum of 5) shims, P/N 643956-20, between the idler spacer and the bearingas are required to achieve the correct alignment between the idler sheave andcompressor sheave.

4 Remove the alignment bar. Tighten the screw to a torque value of800 to 850 inch pounds and recheck the sheave alignment.(continued)M89-6 Supersedes M88-6 Technical Portions AreFAA Approved10 March 1989M89-6 Page the jam nut on the adjusting bolt and the idler pulley slide nut. The idler pulleyslide nut should be loosened only enough to allow the slide to move freely. Theadjusting bolt should be turned out far enough to allow installation of the the the idler pulley snugly against the belt and tighten the adjusting bolt finger tight intoits socket. At this stage, the idler pulley should be rotatable by hand under the the adjusting bolt two full turns. Secure the adjusting bolt jam nut (275-325 inchpounds) and the idler pulley slide nut (300-350 inch pounds).

5 That the belt tension is 50-70 lbs by one of the following a direct reading belt tension gage such as Burroughs tool No. belt deflection under a 5 lb load at the center of the longest belt span, correctdeflection is .3 - .4 belt tension is not within the above tolerance, loosen the adjusting screw jam nut andthe idler pulley slide nut and readjust the tension, one full turn of the adjusting screwresults in about a 10 pound change in belt NOT OVER TIGHTEN BELTA fter approximately five (5) hours of operation, recheck belt tension, and adjust as required tomaintain 50-70 pounds belt tension.(continued)W A R N I N G:10 March 1989M89-6 Page 3