Spark Ignition Aircraft Engine Endurance Test of Aviation ... - FAA

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The exhaust rocker arm pins 1, 2, and 4 and intake pin 3 were slightly grooved. Figure 66 shows what was typically found, which is considered to be normal wear. Figure 66. Posttest Rocker Arm Pin Figure 67 shows the oil pump housing and oil pump gears at the end of the test. Wear was minimal and there was minimal varnish buildup. Figure 67. Posttest Oil Pump Housing and Oil Pump Gears Figure 68 shows the accessory housing with minimal varnish buildup. Figure 68. Posttest Accessory Housing 41
Visual observation of the intake tubes showed some discoloration with minimal amounts of varnish. 4. SUMMARY. A Lycoming IO360-C model engine, overhauled to new specifications, was used for a 150-hour endurance test on AGE-85. The fuel servo injector jet and distribution nozzles were enlarged, and the engine ignition timing was retarded from the standard setting for 100LL of 20° BTDC to 15°. The cylinder compression ratio was not altered from its standard configuration. The IO360-C engine was originally type certificated to operate on 100- or 100LL-grade ASTM D 910 fuels. The majority of the endurance test was run at maximum engine and oil temperatures with the mixture adjusted to attain best power. Power baseline comparisons were also performed on the engine using AGE-85 at the 15° BTDC ignition timing and ISO at the 20° BTDC timing. AGE-85 produced on average 4.3 (2.8%) more peak horsepower than ISO but required 39.7 lb/hr (56.5%) more fuel mass flow or 5.6 gal/hr (35.0%) more fuel volume flow. This is a consequence of two things: the AGE-85 having less energy density than ISO and the oxygen content of AGE-85. This increased fuel mass flow requirement resulted in a drop in peak power efficiency at the TO power setting, as measured by the BSFC from 0.471 lb/bhp hr for ISO to 0.700 lb/bhp hr for AGE-85. The average peak power BSFC was 0.470 lb/bhp hr for ISO and 0.716 lb/bhp hr for AGE-85. Best economy operations resulted in 2.6 (1.8%) more horsepower when operating on AGE-85 but required 32.3 lb/hr (55.8%) more fuel mass flow. The average efficiency at best economy was much lower for AGE-85 than ISO, with values of 0.415 lb/bhp hr for ISO and 0.640 lb/bhp hr for AGE-85. Operation at peak power on AGE-85 resulted in 20ºF higher average EGTs than ISO. Some of this was the result of retarding the ignition timing by 5° and of adjusting the cooling air pressure to maintain fixed CHTs. The best power average EGTs were found to be 136ºF rich of peak EGT for ISO and 110ºF rich of peak EGT for AGE-85. Air-to-fuel ratio data verified that AGE-85 peak power occurred at mixtures much richer than ISO. However, equivalence ratio data showed that these mixtures were leaner relative to stoichiometry than ISO. The mass densities were measured to be 5.7 lb/gal for ISO and 6.4 lb/gal for AGE-85. The current 100LL aviation gasoline has a standard mass density of 5.87 lb/gal. Using AGE-85 would increase fuel weight by 9% above that of 100LL for an equivalent volume of fuel and would reduce operating range by 35% from 100LL. 42
Page 1 and 2: DOT/FAA/AR-06/43 Office of Aviation
Page 3 and 4: 1. Report No. DOT/FAA/AR-06/43 4. T
Page 5 and 6: LIST OF FIGURES Figure Page 1 Oil F
Page 7 and 8: 46 Posttest Connecting Rod Bearing
Page 9 and 10: LIST OF ACRONYMS 100 low-lead 100LL
Page 11 and 12: more fuel volume flow. Future tests
Page 13 and 14: At the completion of the test, the
Page 15 and 16: The engine was installed in a test
Page 17 and 18: Table 4. Parameter Settings for End
Page 19 and 20: Figure 1. Oil Filter Inspection Fig
Page 21 and 22: Figure 4. Corrected Power at 2700 r
Page 23 and 24: Figure 8. Corrected Power at 2300 r
Page 25 and 26: Figure 10. Corrected BSFC vs Fuel M
Page 27 and 28: Figure 12. Corrected Power and Aver
Page 31 and 32: Table 8 provides a summary of the e
Page 37 and 38: output from all six cylinders. Pist
Page 39 and 40: The oil filter was cut open and the
Page 41 and 42: Figure 29. Top of Piston Face of Cy
Page 43 and 44: Figure 33. Bottom of Piston Face an
Page 45 and 46: Figure 39. Posttest Crankshaft Conn
Page 47 and 48: The camshaft lobes, shown in figure
Page 49 and 50: Figure 59 shows a combustion chambe
Page 51: Figure 63. Posttest Rocker Arm Show
Page 55 and 56: Future testing should address effec
Page 57 and 58: Table A-2. Middle and Rear Main Cra
Page 59 and 60: Table A-4. Valve Tappet Outer Diame
Page 61 and 62: Table A-10. Top Piston Ring Side Cl
Page 63: Table A-14. Intake Valve Seat Width

Spark Ignition Aircraft Engine Endurance Test of Aviation ... - FAA

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