Rev A Sept. 18, 2007 22- 1

Fuel Control

S64F Model Helicopter

Rev A Sept. 18, 2007 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.

Rev A Sept. 18, 2007 22- 3

Engine Control Location

Rev A Sept. 18, 2007 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.

Rev A Sept. 18, 2007 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.

Rev A Sept. 18, 2007 22- 6

Part Power Trim To get the proper number of clicks, some math is required.

EPR Below Target1. Subtract recorded EPR from Target EPR2. 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

Rev A Sept. 18, 2007 22- 7

Part Power TrimEPR Above Target

1. Subtract target EPR from recorded EPR2. Divide Results by 0.007

Recorded EPR ( 1.70) - Target EPR (1.54) = 0.16

0.16/ 0.007 = 23CW 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.

Rev A Sept. 18, 2007 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)

Rev A Sept. 18, 2007 22- 9

MIL IDLE

IDLESLOT

STOP

PART POWERTRIM STOP

MILITARYMARK

Rev A Sept. 18, 2007 22- 10

1. Description of fuel system on Engine.2. Fuel Pump

a. De-Ice heaterb. Fuel Oil coolerc. P & Dd. Fuel Manifolde. Fuel Nozzlesf. Fuel Controlg. Green Tags (All information)h. Fuel lubrication (importance of it)

2. Trouble Shootinga. Fuel pumpb. Pressure and Dump valvec. Fuel control

3. Shop Visita. Fuel Nozzle testb. FCU (test bench)

4. Overviewa. Test

Engine Fuel System Outline

Rev A Sept. 18, 2007 22- 11

Engine Fuel Pump Schematic

Fuel Pump

Pt3 From Engine

Butterfly Valve

(Shown Open)

Fuel De-Icing Heater

Pt3Air DumpedOverboard

Orifice Plate

Fuel De-Icer

Bypass Valve

Fuel In From Tank

Rev A Sept. 18, 2007 22- 12

Pressurizing & Dump Valve

Rev A Sept. 18, 2007 22- 13

P & D Schematic

Rev A Sept. 18, 2007 22- 14

Fuel Manifold & Nozzle

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Fuel Control Internal

Rev A Sept. 18, 2007 22- 16

Engine Control Location

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Differential Pressure Switch: The differential pressure switch closes as Differential pressure across the fuel filter increasespast 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”.

Component Description

Rev A Sept. 18, 2007 22- 18

Fuel Differential Switch

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Fuel System Schematic

Rev A Sept. 18, 2007 22- 20

MB 4-30a

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