Repeat the cold cylinder test for the other magneto positions  on the ignition switch, if necessary. Cooling the engine  between tests is unnecessary. The airflow created by the  propeller, and the cooling effect of the incoming fuel/air  mixture is sufficient to cool any cylinders that are functioning  on one test and not functioning on the next. In interpreting the results of a cold cylinder check,  remember that the temperatures are relative. A cylinder  temperature taken alone means little, but when compared  with the temperatures of other cylinders on the same engine,  it provides valuable diagnostic information. The readings  shown in  Figure 10-56  illustrate this point. On this check,  the cylinder head temperature gauge reading at the time the  engine was shut down was 160 °C on both tests. A review of these temperature readings reveals that, on the  right magneto, cylinder number 3 runs cool and cylinders  5 and 6 run cold. This indicates that cylinder 3 is firing  intermittently, and cylinders 5 and 6 are dead during engine  operation on the plugs fired by the right magneto. Cylinders  4 and 6 are dead during operation on the plugs fired by the  left magneto. Cylinder 6 is completely dead. An ignition  system operational check would not disclose this dead  cylinder, since the cylinder is inoperative on both right and  left switch positions. A dead cylinder can be detected during run-up, since an  engine with a dead cylinder requires a higher than normal  manifold pressure to produce any given rpm below the cut-in  speed of the propeller governor. A dead cylinder could also  be detected by comparing power input and power output with  the aid of a torquemeter. Defects within the ignition system that can cause a cylinder  to go completely dead are: In interpreting the readings obtained on a cold cylinder  check, the amount the engine cools during the check must be  considered. To determine the extent to which this factor should  be considered in evaluating the readings, re-check some of  the first cylinders tested, and compare the final readings with  those made at the start of the check. Another factor to be  considered is the normal variation in temperature between  cylinders and between rows. This variation results from those  design features that affect the airflow past the cylinders. Turbine powerplant maintenance procedures vary widely  according to the design and construction of the particular  engine being serviced. The detailed procedures recommended  by the engine manufacturer should be followed when  performing inspections or maintenance. Maintenance  information presented in this section is not intended to specify  the exact manner in which maintenance operations are to be  performed but is included to convey a general idea of the  procedures involved. For inspection purpose, the turbine  engine is divided into two main sections: the cold and hot. Maintenance of the compressor, or cold section, is one of  concern because damage to blades can cause engine failure.  Much of the damage to the blades arises from foreign  matter being drawn into the turbine engine air intakes. The  atmosphere near the ground is filled with tiny particles of  dirt, oil, soot, and other foreign matter. A large volume of  air is introduced into the compressor, and centrifugal force  throws the dirt particles outward so that they build up to form  a coating on the casing, the vanes, and the compressor blades. Accumulation of dirt on the compressor blades reduces  the aerodynamic efficiency of the blades with resultant  deterioration in engine performance. The efficiency of the  blades is impaired by dirt deposits in a manner similar to that  of an aircraft wing under icing conditions. Unsatisfactory  acceleration and high exhaust gas temperature can result from  foreign deposits on compressor components. An end result of foreign particles, if allowed to accumulate  in sufficient quantity, would be inefficiency. The condition  can be remedied by periodic inspection, cleaning, and repair  of compressor components.  1.  Both spark plugs inoperative 2.  Both ignition leads grounded, leaking, or open 3.  A combination of inoperative spark plugs and  defective ignition leads 4.  Faulty fuel-injection nozzles, incorrect valve  clearances, and other defects outside the  ignition system Turbine Engine Maintenance Compressor Section Cylinder No. Right magneto Temperature readings Left magneto 1 2 3 4 5 6 180 170 100 145 70 60 170 175 170 60 155 45 Figure 10-56.  Readings taken during a cold cylinder check.  10-45