Figure 7-7. Limits for Straightening Bent Propeller Flange
OVERHAUL MANUAL LYCOMING 76 SERIES AIRCRAFT ENGINES Section7
-REMOVEPROPELLERFLANGEBUSHINGBEFORE GRINDING.
MASKHOLESBEFOREPLATING.REPLACE \WITH NEWBUSHINGAFTERPLATING.
Figure 7-8. Reconditioning Crankshaft Oil
Seal Surface
7-40. After inspection, install the flange bushingsgs and then cadminum plate the ground surfaces of
the crankshaft flange. The plating, which should be 0.0005 inch maximum thickness, should be permitted to extend along the crankshaft own in
proper only in the area shown figure 7-7.
7-41. Reconditioning Worn Crankshaft Oil Seal Sur face. If haft oil
inspection personnel have found that the crankshaft seal surface on the shaft itself is damaged to the extent that the oil seal might leak, the following procedures are
ft.
submitted to recondition this area of the cranksha
1. Remove propeller flange bushings nkshaft
from crankshaft flange and note the locations of long and short buushingsreplacement. Do not scribe on shaft. Use Lycoming Special Tool ST-115 to remove flange bushings.
2.
Strip cadmium plate from propeller flange and the area of the oil seal by immersing the shaft in a solution of ammonium nitrate (one pound of ammonium nitrate for each gallon of water).
3.
Set up crankshaft in an external grinder and center carefully.
4.
Use a No. 54 grit wheel and grind the area between the propeller flange and the oil seal face to remove nicks and scratches. Depth of grind must not exceed 0.005 inch (0.010 inch u/s diameter).
NOTE
The grinding wheel, on the corner toward the propeller flange must be dressed to 0.05 inch radius while the op-posite side, toward oil slinger, must be dressed 0.13 inch radius. Both radii must blend perfectly. Do not permit the side of the wheel to touch the propeller flange or face of oil slinger. See figure 7-8.
5. A No. 54 or 60 grinding wheel will produce a finish of approximately 8 to 10 microns. The surface roughness of the oil seal area should not exceed 10 microns before polishing with crocus cloth.
Crankcase,Crankshaft andReciprocatingParts
6.
Polish the oil seal area of the shaft with crocus cloth while the shaft is rotated counter-clockwise when viewed from the flange (front) end of shaft. Do not move the cloth while polishing because the area must be free of spiral marks.
7.
Clean the shaft to remove all traces of grinding dust and mask the bushing holes in the flange.
8.
Cadmium plate (in accordance with AMS2400) the flange and oil seal area of the crankshaft as indicated in figure 7-8. Do not plate beyond the 0.13 inch radius.
9.
After plating, bake the crankshaft at 275°F. + 10°F. for 5 hours to eliminate possibility of surface embrit-tlement.
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