Fuel Control - PowerPoint PPT Presentation

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Fuel Control

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  1. Fuel Control S64F Model Helicopter 22-

  2. Engine Fuel Control • The engine fuel control has three inputs from the cockpit. • N1 from the N1 lever • Collective Bias from the mixing unit (COLLECTIVE) • N2 Beeper trim ( Flat Pitch Topping) • These inputs are adjusted and rigged at time of fuel control installation. 22-

  3. Engine Control Location 22-

  4. Power Control Adjustments • The engine controls are to be rigged after an engine, fuel control or any part of the engine control system is replaced. • After proper rigging of controls is done, the engine can be ground run and part power trim performed. • Before Starting the Engine perform a Fuel Shutoff Check • Ground idle speed check – refer to graph for proper range, idle usually at 43-44%. Adjust at idle TRIM screw. 5 clicks of screw is about 1% N1. • Check Bleed Band Closing Range • Flat Pitch Topping Check is done with N1 at full open and N2 at 100%. Actuate beeper switch to minimum, N2 should be 94%-97%. Actuate beeper switch to maximum, N2 should be 103%-107%. Adjustments are made on the Beeper trim motor. 22-

  5. Power Control Adjustments • The part power trim is done with a calibrated stop specific for each fuel control, and the Bias guns disconnected. The engine is trimmed at a specific EPR target. The adjustments to the MIL screw is done to achieve the specific EPR. Note: When adjusting the EPR down the MIL screw is turned Clockwise. In the down adjustment only turn 10 clicks past target and then back up to target. 22-

  6. Part Power Trim • To get the proper number of clicks, some math is required. EPR Below Target 1. Subtract recorded EPR from Target EPR 2. Divide Results by 0.007 Target EPR (1.54) – Recorded EPR ( 1.47) = 0.07 0.07 / 0.007 = 10 10 is the number of clicks to increase the MIL screw Counter ClockWise 22-

  7. Part Power Trim EPR Above Target 1. Subtract target EPR from recorded EPR 2. Divide Results by 0.007 Recorded EPR ( 1.70) - Target EPR (1.54) = 0.16 0.16/ 0.007 = 23 CW 23 clicks + CW 10 clicks + CCW 10 Clicks When adjusting in the CW direction, always go 10 clicks past and come back 10 click CCW to the correct adjustment. • This will take any slop out of the internal linkage. 22-

  8. Part Power Trim • Once the part power trim is done and the target EPR is met, reconnect the bias gun cables and adjust the bias to nominal (3/4 turn off of the stop) • The process of doing a part power trim is done to ensure that at full power the engine is developing maximum power (military) 22-

  9. MIL IDLE MILITARY MARK STOP IDLE SLOT PART POWER TRIM STOP 22-

  10. Engine Fuel System Outline • Description of fuel system on Engine. • Fuel Pump • De-Ice heater • Fuel Oil cooler • P & D • Fuel Manifold • Fuel Nozzles • Fuel Control • Green Tags (All information) • Fuel lubrication (importance of it) • 2. Trouble Shooting • Fuel pump • Pressure and Dump valve • Fuel control • 3. Shop Visit • Fuel Nozzle test • FCU (test bench) • 4. Overview • Test 22-

  11. Engine Fuel Pump Schematic Fuel De-Icer Bypass Valve Fuel In From Tank Orifice Plate Pt3Air Dumped Overboard Fuel De-Icing Heater Fuel Pump Butterfly Valve (Shown Open) Pt3 From Engine 22-

  12. Pressurizing & Dump Valve 22-

  13. P & D Schematic 22-

  14. Fuel Manifold & Nozzle 22-

  15. Fuel Control Internal 22-

  16. Engine Control Location 22-

  17. Component Description Differential Pressure Switch: The differential pressure switch closes as Differential pressure across the fuel filter increases past 4-5psid (28-34 kPa). The psi. differential indicates contamination and possible ice in the filter. Differential Pressure Indication Light: The differential pressure indication lights are located on the caution advisory panel. The lights are labeled “#1 ENG FUEL BY-PASS” and “#2 ENG FUEL BY-PASS”. 22-

  18. Fuel Differential Switch 22-

  19. Fuel System Schematic 22-

  20. MB 4-30a 22-

  21. 22-

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