MIL-PRF-62439 Fuel Control, Main ElectrohydraulicThis specification covers an electrohydraulic main fuel control used in the gas turbine engine of the M1 tank, referred to herein as "assembly." The assembly is an electrohydraulic device which converts electrical commands to fuel flow and power turbine stator \(PTS\) inlet guide vane \(IGV\) actuator flows and pressures. This assembly also contains the PTS and IGV electrical feedback components.

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MIL-PRF-62439B(AT)

3.4.3 Maximum fuel flow. The assembly shall supply a fuel flow of 799�16 pph

(see 4.5.3.3).

3.4.4 High pressure relief valve operation. The assembly shall provide a pressure relief

valve to limit the pressure at the control discharge port to 1150�25 pounds per square inch gage

(psig) (see 4.5.3.4).

3.4.5 Fuel flow schedule. The assembly shall schedule fuel flow in accordance with

figure 3, with null current set to 275�5 milliamperes (mA) at 0.144 volts root mean square

(Vrms) (see 4.5.3.5).

3.4.6 Cutoff valve and check valve operation. The assembly shall provide a combination

cutoff and fuel flow check valve. The cutoff valve shall be normally open and energized closed

with leakage not to exceed 5 cubic centimeter per minute (cm3/min) at 920�10 psig. The check

valve shall open at 54�5 psig with leakage not to exceed 0.25 cm3/min at 40 to 42 psig

(see 4.5.3.6).

3.4.7 Power turbine stator (PTS) feedback voltage output. The assembly shall provide

an electrical feedback signal proportional to the positioning of the PTS feedback lever. The

position shall be 5.135 to 5.145 inches (in.) in accordance with 12286971. The relationship of

the PTS secondary voltage versus this dimension, for an excitation voltage of 5.773 Vrms on the

primary, shall be as follows:

Specified dimension

PTS secondary voltage

5.140�0.001 in.

1.2499�0.0192 Vrms

6.122�0.001 in.

0.1192�0.0577 Vrms

For specified pin definition, see figure 1 (see 4.5.3.7).

3.4.8 Inlet guide vane (IGV) feedback voltage output. The assembly shall provide an

electrical feedback signal proportional to the positioning of the IGV feedback lever. The

position shall be 5.465 to 5.475 in. in accordance with Drawing 12286971. The relationship of

the IGV secondary voltage versus this dimension for an excitation voltage of 5.773 Vrms on the

primary shall be as follows:

Specified dimension

IGV secondary voltage

5.470�0.001 in.

0.0769�0.0115 Vrms

7.040�0.001 in.

1.2302�0.0346 Vrms

For specified pin definition, see figure 1 (see 4.5.3.8).

3.4.9 PTS actuator flow. The assembly shall provide a relative flow between ports 7 and

8, in accordance with Drawing 12286971, as a function of electrical current to the PTS solenoid.

The relationship of electrical current to the flow shall be as follows (see 4.5.3.9):