TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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(a) First production inspection. The first ten engines when completed, and after successful performance of the overhaul engine test schedule, shall have all cylinders, of each engine, inspected by borescope. If no evidence of scuffing is detected, the sampling inspection method may be applied. (b) Sampling inspection. Under this method, after successful performance of the overhaul engine test schedule, sample engines shall be selected for borescope inspection at the rate of one in every 25 engines or one per month when monthly production is less than 25. If scuffing of cylinder walls is detected, the five engines produced preceding the sample engine and the five engines produced after the sample engine will have all cylinders borescoped. Should there be evidence of scuffing as a result of this inspection, the inspector shall refuse acceptance of these engines and subsequent production engines, until required corrections have been made and evidence to this effect has been presented to inspector. (2) Refer to figures 4-126 through 4-141 to remove upper cover shroud plates. Remove as many fuel injection pump fuel tube support clamps as are accessible with the cover plates removed. Disconnect fuel injector fuel return hoses or tubes and fuel injection pump fuel tubes from injector nozzles (fig. 4-150) using extreme caution not to bend or kink the fuel tubes. (3) Loosen the fuel injector nozzles using open end fixed wrench - 5120-871-7198 (fig. 4- 152). Remove fuel injector nozzle and holder assemblies from the 12 cylinder heads (fig. 4- 153). To facilitate removal of No. 6L nozzle and holder assembly, remove the connector from the nozzle head. This will allow the necessary clearance with the shrouding to remove the nozzle and holder. (4) The relative position of the piston for borescoping the cylinders is in the down position or at the lowest most point of the downward stroke. This enables the inspection of the longest portion of cylinder bore affected by piston travel. To achieve this, the flywheel must be rotated using splined wrench - 5120-793-7895 (fig. 4- 51) allowing two pistons on each bank of cylinders to be in the down position and enabling the complete inspection of an engine with only three turns of the flywheel. The combinations of cylinders that can be inspected at one time are as follows: (a) Nos. 2 and 5 right bank, - 3 and 4 left bank, (b) Nos. 3 and 4 right bank, - 1 and 6 left bank, (c) Nos. 1 and 6 right bank and 2 and 5 left bank. To determine when the pistons to be checked are at the lowest point of the downward stroke, use a brass rod as a gage and insert it through the fuel injector nozzle opening in the cylinder head (fig. 8-5). When piston stroke is in the maximum down position, mark the gage rod at the point where the rod protrudes from the cylinder head nozzle opening. This will facilitate the proper positioning of the following cylinders to be checked. Note. Do not use borescope as a probe or gage in determining position of the piston in the cylinders. The instrument can easily be damaged when engine flywheel is rotated to position pistons for borescoping. (5) During inspection of the cylinders, it is recommended that a record be made of each cylinder checked and the position of any discrepancies noted. Relative position of a cylinder defect can be determined as though reading a clock with the top of the cylinder in the 12:00 position. A wear pattern beginning at the top of the cylinder and extending on a 30 degree angle clockwise, would be recorded as a wear pattern extending from the 12:00 to 1:00 position. 8-8