AIR-FUEL RATIO CONTROL MAINTENANCE - CONTINUED
FUEL RATIO CONTROL AND GOVERNOR CHECK - CONTINUED
Work carefully around an engine that has been started. Failure to follow this warning may cause injury or
Start engine (TM 5-3805-248-10) and operate it for a minimum of five minutes to raise governor and engine tempera-
ture to normal operating temperatures.
Check leak-down rate of fuel ratio control (with engine operating at low idle) as follows:
Connect pressure shutoff valve, pressure regulator and air supply to fitting (40).
Apply 70 kPa (10 psi) air pressure to fuel ratio control.
Turn shutoff valve to OFF and check leak-down rate. Leakage of 3 psi (20 kPa) in 30 seconds is acceptable.
If leakage is more than 3 psi (20 kPa) in 30 seconds, fuel ratio control must be replaced before continuing to next
Keep 10 psi (70 kPa) air pressure on fuel ratio control for step 13.
Read indicator carefully because this reading will be a maximum for only a moment. Maximum indicator
reading is dynamic full torque fuel setting of engine. This setting is .02 in. (0.5 mm) greater than static full
torque setting given on engine information plate of later engines.
From low idle, rapidly move governor control shaft to full FUEL ON position and note reading on indicator. If dynamic
full torque fuel setting is not reached, increase air pressure to ensure there is full fuel ratio control movement. Do not
exceed 15 psi (100 kPa).
Read indicator carefully because this reading will be a maximum for only a moment.
Release all air pressure from fuel ratio control. Start at 900 RPM and rapidly move governor control shaft to full FUEL
ON position and note reading on indicator. Record maximum indicator reading. This is dynamic fuel ratio control set-
ting for engine.