4-18. GENERAL REPAIR INSTRUCTIONS (continued).
Fasteners. Replace any bolt, screw, nut, or fitting with damaged threads. Inspect tapped holes for thread
damage. If cross-threading or galling is evident, retap the holes for next oversize screw or stud. When
retapping will weaken the part or when the cost of a part makes retapping impractical, replace the damaged
part. Chasing threads with the proper size tap or die may often be enough.
Sheet Metal Repair. Repair minor skin cracks by installing patches.
Preparation. Remove grease from parts before installation.
Packing Installation. Lubricate all packing with a thin coating of lubricating oil before installation.
Slightly stretch packing and place into position. Rotate component on flat surface or uniformly press the
packing into position.
Gaskets. To provide added sealing for gaskets, coat both sides with sealant. Remove all traces of previous
gasket and sealant before installing new gasket.
Seal Rings. Coat seal rings with oil and carefully inset into their bores. If a seal ring must be installed
over threaded parts, temporarily wrap the threads with tape to protect the seal ring. Then remove the tape.
Bearings and Shafts. During
assembly of shafts and bearings
in housings, first mount the bearing
shaft. Then install the assembly by applying force to the shaft. When mounting bearings on shafts, always
apply force to the inner races of the bearings.
Bearing Lubrication. Lubricate bearings before reassembly with the
type of lubricant normally used
related housing or container. This will provide lubrication during the first run-in until lubrication from the
system can reach the bearings.