Front Of Engine

Figure 2 Location of Coatings Within Engine which were run at the beginning and end of the 500-hour test. These parameters were monitored for only one uncoated cylinder (cylinder 1) and one coated cylinder (cylinder 12).

A 500-hour engine test protocol was developed by the AAR with the assistance of the engine manufacturers, the oil refining companies, and the technical representatives from the railroads as a cost effective means of_ screening for early failures. Fuels and/or components subjected to and failing the 500-hour test are dropped from further consideration while successfully passing the test would make them candidates for extended in-service testing.

For the 500-hour test, the engine is continuously cycled through a two hour regime consisting of 75 minutes at full power (Notch 8), 15 minutes at half power (Notch 4) and 30 minutes at idle speed. Some minor modifications were made in the test protocol to meet the specific needs generated by the ceramic tests. These modifications included ramping the engine speed slowly from idle to Notch 8 over a period of 16 hours to allow seating of the new parts. Engine performance and cylinder temperature data were collected at each notch position. The engine was allowed to break in for 48 hours before the first performance test was undertaken. An outline of the 500 Hour test is contained in Table VI. (6)

Several fuels were used during the 500-hour test. The first 57 hours of the test were run using DF-2 fuel oil. From test hour 58 through 471, fuels that were left over from other tests were consumed. This included 280 hours of operation on a blend of residual fuel/ DF-2, however, at no time did the No. 6 content of the blend exceed 5 percent by volume. Only DF-2 was used during the second performance test (final) and during the ramp down period in order to remove deposits that may have been generated by the heavy fuel blends. The final nine hours of the test were spent ramping down by operating the engine for one hour in each Notch position from Notch 8 to idle. At the conclusion of the 500-hour test, the engine was torn down for the inspection and analysis of the coatings.

Test Results Preliminary indication of how well the ceramic coatings were surviving was provided by borescope inspections made at each 100 hour interval coupled with an analysis of crankcase oil samples taken every 50 hours throughout the test. The first two borescope inspections provided good visual information revealing no signs of cracking or wear of the ceramic coatings. Normal carbon buildup in the combustion chamber obscured the coatings, making detailfKi inspection of the coatings impossible during the remaining inspections. However, the borescope inspections were continued to

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