There are several different makes and models of cylinder  hones. The burnishing hone is used only to produce the  desired finish on the cylinder wall. The more elaborate  micromatic hone can also be used to straighten out the  cylinder walls. A burnishing hone should not be used in an  attempt to straighten cylinder walls.  [Figure 10-31]  Since  the stones are only spring loaded, they follow the contour  of the cylinder wall and may aggravate a tapered condition.  Deglazing the cylinder walls is accomplished with the use  of a deglazing hone. A cross-hatch pattern must be placed  on the cylinder wall to allow for piston ring break-in. This  is accomplished by a deglazing hone turned by a drill being  moved in and out of the cylinder rapidly.  [Figure 10-32] After the cylinders have been reground or deglazed, or both,  check the size and wall finish, and check for evidence of  overheating or grinding cracks before installing on an engine. Before starting reassembly, all serviceable and new engine  components need to be cleaned, organized, and laid out in the  order they are to be assembled. A popular method of engine  assembly is for the engine to be assembled at one work station  with the same technicians completing the total assembly of  the engine. It is also important to refer to the parts catalog to  ensure that the correct hardware is used during the assembly  of the engine. The engine overhaul manual should be referred  to for information on the use of safety wire, self-locking  nuts, and torque values. During assembly, the components  should be pre-lubricated as the overhaul manual sets forth. It  is important to follow the manufacturer’s overhaul assembly  procedures completely and perform all checks and procedures  that are called for in the manual.  The procedures and equipment used in determining that  an engine is ready for airworthy service and is in excellent  mechanical condition, normally requires the use of a  test stand, or test cell, although the aircraft can be used.  [Figure 10-33]  The method of engine testing or run-in that  takes place during overhaul prior to delivery of the engine  is critical to the airworthiness of the engine. It must be  emphasized that engine run-in is as vital as any other phase  of engine overhaul, for it is the means by which the quality  of a new or newly overhauled engine is checked, and it is  the final step in the preparation of an engine for service.  Thus, the reliability and potential service life of an engine  is in question until it has satisfactorily passed the cell test. The test serves a dual purpose. First, it accomplishes piston  ring run-in and bearing burnishing. Second, it provides  valuable information that it used to evaluate engine  performance and determine engine condition. To provide  proper oil flow to the upper portion of the cylinder barrel  walls with a minimum loss of oil, it is important that piston  rings be properly seated in the cylinder in which they are  installed. The process is called piston ring run-in (break- in) and is accomplished chiefly by controlled operation of  the engine in the high-speed range. Improper piston ring  Cylinder Stone Figure 10-31.  Cylinder honing. Figure 10-32.  Cross-hatch pattern on cylinder wall. Figure 10-33.  Test stand.  Installation and Testing Engine Testing of Reciprocating Engines Reassembly 10-20