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<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html>
<html>
<head>
<title>SR-71 - Section I: Description and Operation</title>
<link type="text/css" rel="stylesheet" href="sr71.css"></link>
</head>
<body>
<img src="images/title-1.jpg" alt="" />
<h1>Introduction</h1>
<p>This section describes SR-71A reconnaissance aircraft. <a href="1a.htm">Subsection 1A</a> describes the SR-71B.</p>
<section>
<h1>The Aircraft</h1>
<p>The SR-71 is a delta-wing, two-place aircraft powered by two axial-flow turbojet engines. The aircraft, built by the Lockheed California Company, features titanium construction and is designed to operate at high altitudes and high supersonic speeds. The aircraft has very thin wings, twin canted rudders mounted on top of the engine nacelles, and a pronounced fuselage "chine" extending from the nose to the leading edge of the wing. The propulsion system uses movable spikes to vary air inlet geometry. Surface controls are elevons and rudders, operated by irreversible hydraulic actuators with artificial pilot control feel. The aircraft can be refueled either in-flight or on the ground through separate receptacles that feed into a common refueling line. A drag chute is provided to augment the six-main wheel brakes. The aircraft is painted black to reduce internal temperatures when at high speed.</p>
<figure id="fig-1-1">
<img src="images/1-1.jpg" alt="" />
<figcaption>Figure 1-1: General Arrangement and Bay Locator Diagram</figcaption>
</figure>
<table border="1">
<tbody>
<tr>
<td>
<p>1</p>
</td>
<td>
<p>Right Chine Bay - Compt D (DEF A, C and M)</p>
</td>
</tr>
<tr>
<td>
<p>2</p>
</td>
<td>
<p>Right Forward Mission Bay - Compt L and N</p>
</td>
</tr>
<tr>
<td>
<p>3</p>
</td>
<td>
<p>Radio Equipment Bay - Compt R</p>
</td>
</tr>
<tr>
<td>
<p>4</p>
</td>
<td>
<p>Right Aft Mission Bay - Compt Q and T</p>
</td>
</tr>
<tr>
<td>
<p>5</p>
</td>
<td>
<p>Left Aft Mission Bay - Compt P and S</p>
</td>
</tr>
<tr>
<td>
<p>6</p>
</td>
<td>
<p>Electronics Bay - Compt E</p>
</td>
</tr>
<tr>
<td>
<p>7</p>
</td>
<td>
<p>Left Forward Mission Bay - Compt K and M</p>
</td>
</tr>
<tr>
<td>
<p>8</p>
</td>
<td>
<p>Camera Bay - Compt C</p>
</td>
</tr>
<tr>
<td>
<p>9</p>
</td>
<td>
<p>Pitot Mast</p>
</td>
</tr>
<tr>
<td>
<p>10</p>
</td>
<td>
<p>HF Antenna</p>
</td>
</tr>
<tr>
<td>
<p>11</p>
</td>
<td>
<p>Localizer Antenna</p>
</td>
</tr>
<tr>
<td>
<p>12</p>
</td>
<td>
<p>Radar or OBC Equipment - Compt A</p>
</td>
</tr>
<tr>
<td>
<p>13</p>
</td>
<td>
<p>Ejection Seat</p>
</td>
</tr>
<tr>
<td>
<p>14</p>
</td>
<td>
<p>Forward UHF Antenna (Left Side)</p>
</td>
</tr>
<tr>
<td>
<p>15</p>
</td>
<td>
<p>ANS Platform and Computer</p>
</td>
</tr>
<tr>
<td>
<p>16</p>
</td>
<td>
<p>IFF Antenna</p>
</td>
</tr>
<tr>
<td>
<p>17</p>
</td>
<td>
<p>Radar Recorder</p>
</td>
</tr>
<tr>
<td>
<p>18</p>
</td>
<td>
<p>Electrical Load Center</p>
</td>
</tr>
<tr>
<td>
<p>19</p>
</td>
<td>
<p>Air Refueling Receptacle</p>
</td>
</tr>
<tr>
<td>
<p>20</p>
</td>
<td>
<p>Mission Recorders</p>
</td>
</tr>
<tr>
<td>
<p>21</p>
</td>
<td>
<p>Technical Objective Camera</p>
</td>
</tr>
<tr>
<td>
<p>22</p>
</td>
<td>
<p>Technical Objective Camera or Radar Recorder</p>
</td>
</tr>
<tr>
<td>
<p>23</p>
</td>
<td>
<p>EIP</p>
</td>
</tr>
<tr>
<td>
<p>24</p>
</td>
<td>
<p>Aft UHF Antenna (Right Side)</p>
</td>
</tr>
<tr>
<td>
<p>25</p>
</td>
<td>
<p>Forward Bypass Doors</p>
</td>
</tr>
<tr>
<td>
<p>26</p>
</td>
<td>
<p>Porous Bleed Air Outlets</p>
</td>
</tr>
<tr>
<td>
<p>27</p>
</td>
<td>
<p>Drag Chute Receptacle</p>
</td>
</tr>
<tr>
<td>
<p>28</p>
</td>
<td>
<p>Roll and Pitch Mixer</p>
</td>
</tr>
<tr>
<td>
<p>29</p>
</td>
<td>
<p>CW Receive Antenna (DEF H)</p>
</td>
</tr>
<tr>
<td>
<p>30</p>
</td>
<td>
<p>Ejector Flaps</p>
</td>
</tr>
<tr>
<td>
<p>31</p>
</td>
<td>
<p>J-58 Engine</p>
</td>
</tr>
<tr>
<td>
<p>32</p>
</td>
<td>
<p>Movable Spike</p>
</td>
</tr>
<tr>
<td>
<p>33</p>
</td>
<td>
<p>VHF Antenna (Left Side)</p>
</td>
</tr>
<tr>
<td>
<p>34</p>
</td>
<td>
<p>SAS Gyros</p>
</td>
</tr>
<tr>
<td>
<p>35</p>
</td>
<td>
<p>Digital and AR1700 Recorders (EIP)</p>
</td>
</tr>
<tr>
<td>
<p>36</p>
</td>
<td>
<p>DEF H</p>
</td>
</tr>
<tr>
<td>
<p>37</p>
</td>
<td>
<p>Liquid Oxygen Containers</p>
</td>
</tr>
<tr>
<td>
<p>38</p>
</td>
<td>
<p>TACAN Antenna</p>
</td>
</tr>
<tr>
<td>
<p>39</p>
</td>
<td>
<p>DEF H Centerline Receive Antenna</p>
</td>
</tr>
<tr>
<td>
<p>40</p>
</td>
<td>
<p>UHF-ADF Antenna</p>
</td>
</tr>
<tr>
<td>
<p>41</p>
</td>
<td>
<p>Glide Slope Antenna</p>
</td>
</tr>
<tr>
<td>
<p>42</p>
</td>
<td>
<p>SLR Antenna</p>
</td>
</tr>
</tbody>
</table>
<h2>Dimensions</h2>
<table border="1">
<tbody>
<tr>
<td>
<p>Length (overall)</p>
</td>
<td>
<p>107.4 ft.</p>
</td>
</tr>
<tr>
<td>
<p>Height (to top of rudders)</p>
</td>
<td>
<p>18.5 ft.</p>
</td>
</tr>
<tr>
<td>
<p>Wing span</p>
</td>
<td>
<p>55.6 ft.</p>
</td>
</tr>
<tr>
<td>
<p>Wing area (reference)</p>
</td>
<td>
<p>1605 sq.ft.</p>
</td>
</tr>
<tr>
<td>
<p>Tread (MLG middle wheel centerlines)</p>
</td>
<td>
<p>16.67 ft.</p>
</td>
</tr>
</tbody>
</table>
<h2>Gross Weight</h2>
<p>The loaded gross weight of the aircraft varies from approximately 135,000 to over 140,000 pounds. Zero fuel weight varies from 56,500 to more than 60,000 pounds.</p>
<div class="note">
<p>Use SR-71 manual of weight and balance data applicable to specific aircraft to compute aircraft performance.</p>
</div>
</section>
<section>
<h1>Fuel</h1>
<p>The operating envelope of the JT11D-20 engine requires special fuel. The fuel is not only the source of energy but is also used in the engine hydraulic system. During high Mach flight, the fuel is also a heat sink for the various aircraft and engine accessories which would otherwise overheat at the high temperatures encountered. This requires a fuel having high thermal stability so that it will not break down and deposit coke and varnishes in the fuel system passages. A high luminometer number (brightness of flame index) is required to minimize transfer of heat to the burner parts. Other items are also significant, such as the amount of sulfur impurities tolerated. Advanced fuels, JP-7 (PWA 535) and PWA 523E, were developed to meet the above requirements.</p>
<p>JP-7 and PWA 523E contain one gallon of PWA 536 lubricity additive per 5200 gallons of fuel to ensure adequate lubrication of fuel hydraulic pumps.</p>
</section>
<section>
<h1>Engine and Afterburner</h1>
<p>Thrust is supplied by two Pratt & Whitney JT11D-20 bleed bypass turbojet engines with afterburners. (See <a href="#fig-1-2">Figure 1-2</a>.) The engines are designed for continuous operation at compressor inlet temperatures above 400°C, which are associated with high Mach flight. The engine has a single-rotor, nine-stage, 8.8:1 pressure ratio compressor utilizing a compressor bleed bypass at high Mach. When opened, bypass valves bleed air from the fourth stage of the compressor, and six ducts route it around the rear stages of the compressor, the combustion section, and the turbine. The bleed air re-enters the turbine exhaust around the front of the afterburner where it is used for increased thrust and cooling. The transition to bypass operation is scheduled by the main fuel control as a function of compressor inlet temperature and engine speed. The transition normally occurs in a CIT range of 85° to 115°C, corresponding to a Mach range of 1.8 to 2.0.</p>
<p>See <a href="4.htm">Section IV</a> for Complete List Of Bay Designations and Equipment Locations</p>
<p>When on the ground, or at low Mach numbers, engine speed varies with throttle movement when the throttle is between IDLE and slightly below the Military stop. At higher settings, up to maximum afterburner, the main fuel control schedules engine speed as a function of CIT and modulates the variable area exhaust nozzle to maintain approximately constant RPM. Throttle movement in the afterburning range only changes the afterburner fuel flow, nozzle position, and thrust. At high Mach number and constant inlet conditions, engine speed is essentially constant for all throttle positions down to and including IDLE. At a fixed throttle position, engine speed will vary according to main fuel control schedule when CIT (Mach) changes.</p>
<p>The engine contains a two-stage turbine. Turbine discharge temperatures are monitored by exhaust gas temperature indication. A chemical ignition system is used to ignite the low vapor pressure fuel. A separate engine-driven hydraulic system, using fuel as hydraulic fluid, operates the exhaust nozzle, chemical ignition system dump, compressor bypass, starting bleed systems, and Inlet Guide Vanes (IGV). The main fuel pump, engine hydraulic pump and tachometer are driven by the main engine gearbox. The afterburner fuel pump is powered by an air turbine, driven by compressor discharge air.</p>
<figure id="fig-1-2">
<img src="images/1-2.jpg" alt="" />
<figcaption>Figure 1-2: JT11D-20 Engine</figcaption>
</figure>
<table border="1">
<tbody>
<tr>
<td>
<p>1</p>
</td>
<td>
<p>Inlet Case</p>
</td>
</tr>
<tr>
<td>
<p>2</p>
</td>
<td>
<p>Variable IGV</p>
</td>
</tr>
<tr>
<td>
<p>3</p>
</td>
<td>
<p>Forward Compressor Section (4 stages)</p>
</td>
</tr>
<tr>
<td>
<p>4</p>
</td>
<td>
<p>Internal Bleeds (24)</p>
</td>
</tr>
<tr>
<td>
<p>5</p>
</td>
<td>
<p>Bypass Chamber</p>
</td>
</tr>
<tr>
<td>
<p>6</p>
</td>
<td>
<p>External Bleeds (12)</p>
</td>
</tr>
<tr>
<td>
<p>7</p>
</td>
<td>
<p>Chemical Ignition Tank (TEB)</p>
</td>
</tr>
<tr>
<td>
<p>8</p>
</td>
<td>
<p>Main Burner Injector Probe</p>
</td>
</tr>
<tr>
<td>
<p>9</p>
</td>
<td>
<p>Bleed Bypass Tubes (6)</p>
</td>
</tr>
<tr>
<td>
<p>10</p>
</td>
<td>
<p>Afterburner Spray Bar Rings (4)</p>
</td>
</tr>
<tr>
<td>
<p>11</p>
</td>
<td>
<p>Aft Engine Mount Ring</p>
</td>
</tr>
<tr>
<td>
<p>12</p>
</td>
<td>
<p>Afterburner Liner</p>
</td>
</tr>
<tr>
<td>
<p>13</p>
</td>
<td>
<p>Variable Area Exhaust Nozzle</p>
</td>
</tr>
<tr>
<td>
<p>14</p>
</td>
<td>
<p>Exhaust Nozzle Actuators (4)</p>
</td>
</tr>
<tr>
<td>
<p>15</p>
</td>
<td>
<p>Flame Holders (4)</p>
</td>
</tr>
<tr>
<td>
<p>16</p>
</td>
<td>
<p>Turbine Section and Bearing</p>
</td>
</tr>
<tr>
<td>
<p>17</p>
</td>
<td>
<p>Hydraulic Filters (2)</p>
</td>
</tr>
<tr>
<td>
<p>18</p>
</td>
<td>
<p>Burner Can (8)</p>
</td>
</tr>
<tr>
<td>
<p>19</p>
</td>
<td>
<p>Aft Compressor Bearing</p>
</td>
</tr>
<tr>
<td>
<p>20</p>
</td>
<td>
<p>Main Gearbox</p>
</td>
</tr>
<tr>
<td>
<p>21</p>
</td>
<td>
<p>Main Fuel Control</p>
</td>
</tr>
<tr>
<td>
<p>22</p>
</td>
<td>
<p>Main Fuel Pump</p>
</td>
</tr>
<tr>
<td>
<p>23</p>
</td>
<td>
<p>Reduction Gear Box</p>
</td>
</tr>
<tr>
<td>
<p>24</p>
</td>
<td>
<p>GV Actuators (2)</p>
</td>
</tr>
<tr>
<td>
<p>25</p>
</td>
<td>
<p>Front Compressor Bearing</p>
</td>
</tr>
<tr>
<td>
<p>26</p>
</td>
<td>
<p>Intel Case Island Cover</p>
</td>
</tr>
</tbody>
</table>
<h2>Maximum Rated Thrust</h2>
<p>
<span>Maximum rated thrust is obtained in afterburning by placing the throttle against the quadrant forward stop. The maximum afterburning</span>
<u>uninstalled</u>
<span>thrust of each engine at sea level, static condition, and standard day is 34,000 pounds. Takeoff thrust in maximum afterburner is illustrated in <a href="#fig-1-3">Figure 1-3</a> at sea level pressure altitude. It shows the variation in thrust with ambient temperature and the effect of airspeed during the takeoff acceleration.</span>
</p>
<figure id="fig-1-3">
<img src="images/1-3.jpg" alt="" />
<figcaption>Figure 1-3: Takeoff Thrust</figcaption>
</figure>
<h2>Partial Afterburning Thrust</h2>
<p>Afterburning fuel flow and thrust are modulated by moving the throttle between the Military detent and the quadrant forward stop. Minimum afterburning thrust is obtained with the throttle just forward of Military and is approximately 85% of maximum afterburning thrust at sea level and approximately 55% at high altitude. Afterburner ignition is automatically actuated when the throttle is advanced past the detent. The time required to obtain afterburner ignition after moving the throttle past the detent is a function of afterburner fuel manifold fill time. The fill time can be up to three seconds at sea level and up to seven seconds at altitude. Afterburner fuel flow is terminated when the throttle is retarded below the detent. The basic engine operates at Military rated thrust during all afterburning operation.</p>
<h2>Military Thrust</h2>
<p>Military thrust is the maximum non-afterburning thrust and is obtained by placing the throttle against the aft side of the Military detent. At sea level static conditions, military thrust is approximately 70% of maximum thrust. At high altitude, military thrust is approximately 28% of the maximum thrust available. <a href="#fig-1-4">Figure 1-4</a> illustrates the variation in military thrust with ambient temperature and airspeed at sea level pressure altitude.</p>
<figure id="fig-1-4">
<img src="images/1-4.jpg" alt="" />
<figcaption>Figure 1-4: Military Thrust</figcaption>
</figure>
<h2>Idle Thrust</h2>
<p>Idle thrust is the minimum non-afterburning thrust level. With the throttle in IDLE, the engine operates at approximately 3975 RPM up to 60°C (140°F). At higher ambient temperatures, RPM increases approximately 50 RPM per 1°C. Idle thrust is illustrated in <a href="#fig-1-5">Figure 1-5</a>, at sea level pressure altitude, for airspeeds typical of a landing and deceleration.</p>
<figure id="fig-1-5">
<img src="images/1-5.jpg" alt="" />
<figcaption>Figure 1-5: Idle Thrust</figcaption>
</figure>
<section data-title="Throttles">
<h3>Throttles and Throttle Settings</h3>
<p>Two throttle levers are located in a quadrant on the pilot's left forward console. The right throttle is mechanically linked to the right engine main fuel control. The left throttle is linked to the left engine afterburner fuel control. The afterburner and the main fuel controls are interconnected by a closed loop cable. The throttle quadrant has three labeled positions, OFF, IDLE, and AFTERBURNER, and an unlabeled Military power stop. See <a href="#fig-1-6">Figure 1-6</a>. The non-afterburning operating range of the engine is between IDLE and Military.</p>
<figure id="fig-1-6">
<img src="images/1-6.jpg" alt="" />
<figcaption>Figure 1-6: Throttle Quadrant</figcaption>
</figure>
<p>A spring-loaded push-button switch is located on the right throttle knob. When depressed, the pilot's microphone is connected to the selected radio transmitter.</p>
<p>A throttle air inlet restart switch is located on the inboard side of the right throttle. The switch is used for restarting both air inlets simultaneously.</p>
<h4>Off</h4>
<p>In the OFF position, the windmill bypass valve cuts off fuel from the burner cans and routes it back to the aircraft system. This provides cooling for engine oil, fuel pump, and fuel hydraulic pump when an engine is windmilling.</p>
<h4>Idle</h4>
<p>When a throttle is moved forward from OFF to IDLE, a roller drops over a hidden ledge at the IDLE position. This ledge prevents the engine from being inadvertently cut off when the throttles are retarded to IDLE. The throttles must be lifted to be moved from IDLE to OFF.</p>
<h4>Afterburner</h4>
<p>The throttle must be slightly raised and pushed forward to clear the Military stop before additional forward movement of the throttle can initiate afterburner ignition.</p>
<p>The AFTERBURNER range extends from the Military stop to the quadrant forward stop.</p>
<h4>Start</h4>
<p>There is no distinct throttle position for starting. Starting is accomplished by moving the throttle from OFF to IDLE as the engine is accelerated by the starter. As the proper engine speed is reached, fuel is directed to the engine burners by actuation of the windmill bypass valve and the chemical ignition system is actuated by fuel pressure.</p>
<h4>Throttle Friction Lever</h4>
<p>Throttle friction is controlled by a lever located on the inboard side of the throttle quadrant. Moving the lever forward, as the INCREASE FRICTION label indicates, progressively increases friction.</p>
<h4>TEB Remaining Counters</h4>
<p>Mechanical digital counters, aft of each throttle, indicate the number of TEB shots remaining for each engine. The counters are spring wound and set to 16 prior to engine start. Each time a throttle is moved forward from OFF to IDLE, or from Military to AFTERBURNER, the corresponding counter indication decreases by 1.</p>
<h4>Tachometers</h4>
<p>Tachometers for each engine are mounted on the right side of the pilot's instrument panel. They indicate engine speed in revolutions per minute by means of a main pointer and dial calibrated to 10,000 RPM, and a smaller dial and subpointer which make one complete revolution for each 1000 RPM. The tachometers are self-energized and operate independently of the aircraft electrical system.</p>
</section>
<section>
<h3>Engine Fuel System</h3>
<p>Engine fuel system components include the engine-driven fuel pump, main fuel control, windmill bypass valve and variable area fuel nozzles in the main burner section. (See <a href="#fig-1-7">Figure 1-7</a>.)</p>
<figure id="fig-1-7">
<img src="images/1-7.jpg" alt="" />
<figcaption>Figure 1-7: Engine and Afterburner Fuel System</figcaption>
</figure>
<h4>Main Fuel Pump</h4>
<p>The engine-driven main fuel pump is a two-stage unit. The first stage, a single centrifugal pump, acts as a boost stage. The second stage consists of two parallel gear-type pumps with discharge check valves. The parallel pump and check valve arrangement permits continued operation if either pump fails.</p>
<h4>Main Fuel Control</h4>
<p>The main fuel control meters main burner fuel flow, controls the bleed bypass, start bleed valves, IGV, and exhaust nozzle modulation. It regulates main engine thrust as a function of throttle position, compressor inlet air temperature, main burner pressure, and engine speed. The bypass, start-bleed valve positions and IGV are controlled as a function of engine speed, biased by CIT. Afterburner operation is always at Military-rated engine speed and EGT. The control has a remote trimmer for EGT regulation. There is no emergency fuel control system.</p>
<h4>Windmill Bypass and Dump Valve</h4>
<p>The windmill bypass and dump valve directs fuel to the engine burners for normal operation or bypasses fuel to the recirculation system for accessory, engine component, and engine oil cooling during windmilling operation. The valve responds to signals from the main fuel control. The valve opens to drain the engine fuel manifold when the engine is shut down.</p>
<h4>Fuel Nozzles</h4>
<p>The engine has an eight-unit can-annular combustion section with 48 variable-area, dual-orifice fuel nozzles. The nozzles are arranged in clusters of six nozzles per burner. Each nozzle has a fixed area primary metering orifice and a variable area secondary metering orifice, discharging through a common opening. The secondary orifice opens as a function of primary pressure drop.</p>
<h4>Combustion Chamber Drain Valve</h4>
<p>The main engine ignition system plumbing is equipped with a fuel purge or "Dribble Tee". This allows fuel from the main fuel pump interstage to flush residual ignition fluid (TEB) from the ignition probe. It prevents "coking" from occurring which would restrict the ignition probe and prevent engine ignition. Hence, fuel in small quantity should drain from the main burner case overboard drain fitting anytime there is fuel pressure to the engine pump inlet, due to fuel boost pump operation or tank pressure developed by the LN<sub>2</sub> fuel tank pressurization system. If fuel does not drain normally, either the chemical ignition system probe is plugged or the burner drain has malfunctioned. The normal leakage from the main burner case overboard drain should be confirmed before start. If the overboard drain is restricted, it will increase the "wetted" fuel area in the burner and could result in severe torching during engine start.</p>
<h4>Fuel Flow Indicators</h4>
<p>Fuel flow indicators for each engine, mounted on the right side of the pilot's instrument panel, display total fuel flow (engine and afterburner) plus tank return flow, if any. Dial calibrations are provided in 5000 pound per hour increments to 95,000 pph. Five center digit windows show fuel flow to the nearest 100 pph. Power for the indicators is supplied from the essential AC bus through the L and R FLOW circuit breakers on the pilot's right console.</p>
<div class="note">
<p>Tank return flow forms an appreciable portion of the indication when at or below Military.</p>
</div>
</section>
<section>
<h3>Afterburner Fuel System</h3>
<h4>Afterburner Fuel Pump</h4>
<p>The afterburner fuel pump is a high speed, single stage centrifugal pump. The pump is driven by an air turbine, operated by engine compressor discharge air. The compressor discharge air supply is regulated by a butterfly valve in response to the demand of the afterburner fuel control.</p>
<h4>Afterburner Fuel Control</h4>
<p>The hydromechanical afterburner fuel control schedules fuel flow as a function of throttle position, main burner pressure, and compressor inlet temperature. Fuel flow is metered to discharge fuel from the four concentric afterburner spray-bar rings.</p>
</section>
<section>
<h3>Fuel Derich System</h3>
<p>A derichment system on each engine protects against severe turbine over-temperature. If the respective EGT indicator reaches 860°C while the system is armed, the fuel/air ratio in the engine burner cans is automatically reduced (deriched). A signal from the EGT gage actuates a solenoid-operated valve which bypasses metered engine fuel from the fuel/oil cooler to the afterburner fuel pump inlet. See Figures <a href="#fig-1-7">1-7</a> and <a href="#fig-1-8">1-8</a>. Once actuated, the solenoid valve is held open until the system is turned off or rearmed. A red, flashing FUEL DERICH warning light illuminates when the valve for the respective engine is open.</p>
<p>Derichment at sea level decreases thrust approximately 5% in maximum afterburner; 7% at Military. Derichment during supersonic cruise decreases engine thrust approximately 45% in maximum afterburner (overall engine/inlet thrust loss is about 10% for the deriched engine since derichment has no effect on CIP) and may cause the afterburner to blow out. Continuous operation with the engine deriched does not harm the engine (provided derichment can reduce EGT to normal limits).</p>
<p>After an unstart, do not move the fuel derich switch from ARM unless inlet roughness has cleared and the inlet has restarted (CIP re-covered); otherwise, severe over-temperature can result. Do not attempt to relight the afterburner while deriched. Lighting the afterburner while deriched can result in engine speed suppression of up to 750 RPM.</p>
<h4>Fuel Derich Arming Switch</h4>
<p>A three-position FUEL DERICH arming toggle switch is located on the pilot's left instrument side panel. In the ARM (center) position, the derich circuit is armed and the derich solenoid valve will open and remain open if the respective EGT indication reaches 860°C. In the OFF (down) position, the derich solenoid valve is closed and the system cannot provide derichment. The REARM (up) position is spring-loaded and allows the pilot to rearm the fuel derich system without moving the switch to OFF. Power for the switch is furnished by the essential DC bus through the L and R FUEL DERICH circuit breakers on the pilot's left console.</p>
<h4>Fuel Derich System Test Switch</h4>
<p>A three-position toggle switch, labeled FUEL DERICH SYSTEM, is located on the pilot's left console. The switch is labeled L (left), R (right) and is spring-loaded to the center (off) position. When the switch is moved to the L or R position, the digital indication on the respective EGT gage slews toward 1198°C. When the EGT gage indication exceeds 860°C, the red jewel light in the gage illuminates; and, if the FUEL DERICH switch is in ARM, the respective fuel derich warning light flashes and the derich solenoid valve opens.</p>
<h4>Fuel Derich Warning Light</h4>
<p>Two red, flashing fuel derich warning lights are located on the right side of the pilot's instrument panel. A light flashes when the fuel derich system for the respective engine is activated (derich solenoid valve open) and continues flashing until the fuel derich system is rearmed or off.</p>
</section>
<section data-title="EGT Trim System">
<h3>Exhaust Gas Temperature (EGT) Trim System</h3>
<figure id="fig-1-8">
<img src="images/1-8.jpg" alt="" />
<figcaption>Figure 1-8: EGT Indication and Control System</figcaption>
</figure>
<h4>EGT Gages</h4>
<p>Two EGT gages, one for each engine, are located on the right side of the pilot's instrument panel. Each gage has a digital indicator that shows turbine discharge temperature from 0° to 1198°C, a HOT (red) and COLD (yellow) condition flag, a red "jewel" over temperature warning light that illuminates when the EGT digital indication reaches 860°C, and a power OFF warning flag. Each indicator receives power from the essential AC bus through its respective L or R EGT IND circuit breaker on the pilot's right console.</p>
<h4>EGT Trim Switches</h4>
<p>Two four-position EGT trim switches, one for each engine, are located on the pilot's left console. The positions are labeled AUTO (left), INCR (up), DECR (down) and HOLD (center). When a switch is held in INCR, a small electric motor on the engine fuel control increases the ratio of main burner fuel flow to main burner combustion pressure and thus increases the turbine discharge temperature (EGT). Holding a switch in DECR runs the motor in the opposite direction and decreases EGT. The switches have no effect on RPM as long as the nozzles are modulating to provide the scheduled engine speed. However, engine speed will increase (or decrease) with increasing (or decreasing) EGT when nozzle position is limited full closed (or open).</p>
<p>An EGT "permission" circuit prevents automatic trimming in either direction and manual uptrim when the respective throttle is positioned below Military or the engine is deriched. Manual EGT downtrim remains available even when the permission circuit is on (throttle below Military or engine deriched). Power for the trim motors is furnished by the essential AC bus through the L and R EGT TRIM circuit breakers on the pilot's right console. Power for the permission circuit is furnished by the essential DC bus through the L and R EGT circuit breakers on the pilot's left console.</p>
<h4>Automatic EGT Trim</h4>
<p>When an EGT trim switch is in AUTO, the respective throttle is positioned at or above Military, and that engine is not deriched, the permission circuit is opened (off) to allow automatic EGT trim. The electric trim motor for the respective engine regulates its main fuel control and automatically provides EGT within a 10°C nominal deadband. See <a href="#fig-1-9">Figure 1-9</a>.</p>
<figure id="fig-1-9">
<img src="images/1-9.jpg" alt="" />
<figcaption>Figure 1-9: Nominal EGT Schedule</figcaption>
</figure>
<p>If the EGT for an engine is either above or below the deadband, the system trims EGT toward its deadband. The rate of trimming depends on temperature deviation from the deadband. If EGT is more than 10°C above the deadband, the system downtrims at its maximum rate (approximately 8°C per second), and the HOT flag is displayed on the EGT gage. When the EGT is more than 10°C below the deadband, the system uptrims at 1°C per second and the COLD flag is displayed. When EGT is 10°C or less from its deadband, the system trims at only 1/3°C per second and the condition flags retract.</p>
<div class="caution">
<p>If EGT tends to hunt or has an abnormal tendency to uptrim or downtrim while AUTO is selected, the corresponding engine should be operated in manual trim and the condition reported following flight. An EGT over-temperature may occur if continued operation in AUTO is attempted.</p>
</div>
<div class="note">
<ul class="list-circle">
<li>
<p>The EGT condition flags do not operate when manual EGT trim is used.</p>
</li>
<li>
<p>With AUTO EGT selected, the COLD condition flag will not operate when the permission circuit is on (throttle below Military or deriched).</p>
</li>
<li>
<p>With AUTO EGT selected, the HOT condition flag will operate regardless of the condition of the permission circuit.</p>
</li>
</ul>
</div>
<p>
<span>Auto EGT is normally used during the engine trim check; however, if the system is obviously uptrimmed above normal limits,</span>
<u>reduce power</u>
<span>and manually downtrim prior to resetting military power.</span>
</p>
<p>The hot flag over-temperature warning circuit is continually energized when in AUTO EGT. A hot flag may appear at throttle positions below the permission switch and should be corrected by manually downtrimming or retarding the throttle.</p>
<p>Repeated rapid throttle movements forward and back through the permission switch operating range can cause military EGT to increase sufficiently to produce derichment. This EGT ratcheting is caused by a lag in thermocouple response and can be avoided by selecting manual trim when repeated rapid throttle movements to and below Military are expected.</p>
<p>Selecting the spring-loaded HOLD (center) position deactivates automatic trimming and maintains the existing EGT trimmer setting.</p>
<div class="note">
<p>When AUTO EGT is selected, a brief spurious flag indication may occur in response to the EGT and CIT conditions that existed when AUTO EGT trim was last used. Valid flag indications and normal AUTO EGT trim operation should occur within five seconds.</p>
</div>
</section>
<section data-title="Inlet Parameters">
<h3>Inlet Parameter Indications</h3>
<figure id="fig-1-10">
<img src="images/1-10.jpg" alt="" />
<figcaption>Figure 1-10: Nominal CIP Range</figcaption>
</figure>
<h4>Compressor Inlet Pressure (CIP) Gage</h4>
<p>The CIP gage, on the left of the pilot's instrument panel, has an L and R needle which indicate inlet static pressure at the face of each compressor, and a striped third needle that indicates expected normal CIP. The position of the striped pointer is governed by DAFICS using pressures sensed by the pitot-static system. The indication varies with Mach and KEAS so that the striped needle shows "normal" CIP for the flight condition. A substantial difference between the striped needle and actual CIP indicates improper inlet operation. Higher actual pressure at normal speeds and altitudes may produce unstarts. Lower pressure indicates poor pressure recovery due to improper spike and/or bypass door settings except at abnormal angles of attack or yaw conditions, where inlet operation is automatically biased to less than normal recovery. The spread between inlet CIP indications (L and R needles) should not exceed 1 psi. The needle can be used as a guide for bypass door settings during manual operation of one or both inlets; however, it is preferable to keep the L and R needles slightly below the "normal" indication to maintain a margin below unstart pressures. Automatic or manual inlet operation at pressures below the "normal" indication reduces aircraft range.</p>
<p>Power is supplied by the essential AC bus through the CIP circuit breaker on the pilot's right console.</p>
<h4>Compressor Inlet Temperature (CIT) Gage</h4>
<p>A dual indicating CIT gage is mounted on the left side of the pilot's instrument panel. L (left) and R (right) needles indicate the total (ram) air temperature forward of the first compressor stage in the corresponding engine inlet. Major calibrations are marked from 0°C to 500°C. The dial has 50° incremental markings below 300°C. Above 300°C, the gage has increased sensitivity and incremental marks are supplied for each 10°C. Slight differences between left and right CIT indications can be expected; however, differences of more than 15°C while at supersonic cruise speeds should be reported as a discrepancy. Power is furnished by the essential AC bus through the L and R CIT circuit breakers on the pilot's right console.</p>
</section>
<section data-title="Exhaust Nozzle & Ejector">
<h3>Exhaust Nozzle and Ejector System</h3>
<p>The variable-area, iris-type, engine after-burner nozzle is comprised of segments operated by a cam and roller mechanism and four hydraulic actuators. The actuators are operated by fuel hydraulic system pressure. The engine afterburner nozzle is enclosed by a fixed-contour, convergent-divergent ejector nozzle to which free floating trailing edge flaps are attached. In flight, the inlet shock trap bleed and aft bypass doors (when open) supply secondary airflow between the engine and nacelle for cooling. During ground operation, suck-in doors in the aft nacelle area provide cooling air. Intake doors around the nacelle, just forward of the ejector, normally supply tertiary air to the ejector nozzle when subsonic. The tertiary doors and trailing edge flaps are free to open and close with varying internal nozzle pressure (a function of Mach and engine thrust).</p>
<h4>Nozzle Actuation</h4>
<p>The exhaust nozzle control and actuation system is composed of four actuators to position the exhaust nozzle, and an exhaust nozzle control which modulates pressure at the actuators in response to engine speed signals from the main fuel control. The exhaust nozzle control is mounted on the aft portion of the engine.</p>
<h4>Exhaust Nozzle Position (ENP) Indicators</h4>
<p>Two ENP indicators, one for each engine, are located on the right side of the pilot's instrument panel. They are marked from 0 to 10 as an index of nozzle position from closed to open. Each indicator responds to an electrical transducer located near its exhaust nozzle. The transducer is cooled by fuel and is operated by the afterburner nozzle feedback link. Power for the indicators is supplied from the essential AC bus through the L and R ENP circuit breakers on the pilot's right console.</p>
</section>
<section data-title="Engine Bleeds">
<h3>Engine External and Internal Bleeds</h3>
<p>The internal bypass bleed control and actuation system consists of four two-position actuators to move the bleed valves and a pilot valve, within the main fuel control, to establish the pressure to the actuators. The pilot valve controls the bleed valve position in response to a mechanical signal from the main fuel control. Bleed valve position is scheduled within the main fuel control as a function of engine speed and CIT. The external bleed control and actuation system is similar to the internal bleed system, except that three actuators are used.</p>
</section>
<section>
<h3>Engine Inlet Guide Vanes (IGV)</h3>
<p>The engine compressor inlet case houses a two-position inlet guide vane (IGV) system. The guide vanes can be either in the cambered position, which is normal for cruise, or in the axial position which is normal for takeoff and acceleration to intermediate supersonic speed. The IGV axial position (parallel to the airflow) results in more thrust. Actuation to the cambered position occurs at a CIT of 85° to 115°C (about Mach 1.9) during acceleration. The cambered position is mandatory when operating continuously at CIT above 125°C (approximately Mach 2.0). Shifting is normally controlled by the main engine fuel control; however, the shift to the axial position from cambered is prevented if the IGV Lockout Switch is positioned to LOCKOUT. Refer to <a href="#fig-1-11">Figure 1-11</a> for IGV shift scheduling information.</p>
<figure id="fig-1-11">
<img src="images/1-11.jpg" alt="" />
<figcaption>Figure 1-11: Compressor Bleed and IGV Shift Schedule IGV/Bypass Bleed Functions</figcaption>
</figure>
<h4>IGV Lockout Switches</h4>
<p>The shift schedules for the internal bypass bleeds and the inlet guide vanes are identical. There is a positive locking feature which prevents unscheduled IGV shift to axial after the cambered position has been reached. In addition, two-position IGV lockout switches (one for each engine) on the pilot's right console, can lock out IGV shift from cambered to axial. With a lift-loc switch in LOCKOUT, the respective IGV is maintained in the cambered position regardless of internal bleed position. The LOCKOUT position is ineffective until the guide vanes are in the cambered position. The switches cannot cause or prevent IGV shift from axial to cambered. With IGV NORM selected, IGV shift occurs with internal bleed shift. Power for the IGV lockout solenoid circuits is supplied from the essential DC bus through the L and R IGV circuit breakers on the pilot's left console.</p>
<h4>Inlet Guide Vane Position Lights</h4>
<p>Two rotate-to-dim, amber inlet guide vane (IGV) position lights are installed on the right side of the pilot's instrument panel. An indicator is provided for each engine, identified by L or R adjacent to the appropriate light. An IGV light illuminates when the inlet guide vanes of the respective engine shift to the axial position as scheduled by the main fuel control. The light extinguishes when the IGV reaches the cambered position. Inlet guide vane position is sensed by a switch on the engine compressor case which operates when the guide vanes reach or leave the cambered position. Power for the lights is furnished by the essential DC bus through the WARN 2 light circuit breaker on the pilot's left console.</p>
<ol class="list-alpha">
<li>
<p>The IGV lights must be off (IGV cambered) during start and at idle.</p>
</li>
<li>
<p>The IGV lights must be on (IGV axial) for takeoff.</p>
</li>
<li>
<p>The IGV lights must be off (IGV cambered) above 150°C (approximately Mach 2.2).</p>
</li>
</ol>
</section>
<section>
<h3>Oil Supply System</h3>
<p>The engine and speed-reduction gearbox are lubricated by an engine-contained, "hot tank", closed system. The oil is cooled by circulation through an engine fuel-oil cooler. The oil tank is mounted on the lower right side of the engine compressor case. Tank volume is 6.7 US gallons. The oil tank is serviced to 5.15 US gallons. The oil is gravity-fed to the main oil pump which forces the oil through a filter and the fuel-oil cooler. The filter is equipped with a bypass in case of clogging. The oil is distributed to the engine bearings and gears from the fuel-oil cooler. Oil screens are installed at the lubricating jets for additional protection. Scavenge pumps return the oil to the tank where it is de-aerated. A pressure regulating valve keeps flow and pressure relatively constant during all flight conditions. Oil quantity warning lights are provided.</p>
<p>The approved oil is MIL-L-87100 (PWA 524). At low ambient temperatures, oil may be diluted with trichloroethylene, Federal Specification O-T-634, Type 1.</p>
<h4>Main Fuel-oil Cooler</h4>
<p>Engine oil temperature is controlled by engine fuel which passes through the main fuel-oil heat exchanger. A bypass valve in the cooler passes additional fuel around the cooler when engine requirements are greater than the flow capacity of the cooler (approximately 12,000 pounds per hour).</p>
<h4>Engine Oil Pressure Gages</h4>
<p>An oil pressure gage for each engine is provided on the right side of the pilot's instrument panel. Each gage indicates output pressure of the respective engine oil pump in pounds per square inch, using electrical signals from a fuel-cooled transmitter. The dials are calibrated from 0 to 100 psi in 5-psi increments. Power for the gages is furnished by the essential AC bus 26 volt instrument transformer through the L and R OIL PRESS circuit breakers on the pilot's annunciator panel.</p>
<h4>Engine Oil Temperature Lights</h4>
<p>The L and R OIL TEMP annunciator lights are not functional. The OIL TEMP lights only illuminate when the IND & LT TEST push-button switch is depressed.</p>
<h4>Low Oil Quantity Lights</h4>
<p>L and R OIL QTY warning lights, on the pilot's annunciator panel, illuminate when oil quantity in the respective engine oil tank is less than 2-1/4 gallons.</p>
</section>
<section>
<h3>Engine Fuel Hydraulic System</h3>
<p>Each engine is provided with a fuel hydraulic system for actuation of the afterburner exhaust nozzle, IGVs, and the start and bypass bleed valves. Fuel hydraulic pressure is also required to dump the chemical ignition system. An engine-driven pump maintains system pressures up to 1800 psi with a maximum flow of 50 gpm (approximately 19,700 pph) for transient requirements. Engine fuel is supplied to the pump from the main fuel pump boost stage. Some high-pressure fuel is diverted from the hydraulic system to cool the non-afterburning recirculation line and the windmill bypass valve discharge line. This fuel is returned to the aircraft fuel system. Low-pressure fuel from the hydraulic pump case is returned to the main fuel pump boost stage. Hydraulic system loop cooling is provided by the compensating fuel supplied by the main fuel pump.</p>
</section>
<section>
<h3>Accessory Drive System (ADS)</h3>
<p>An ADS is mounted forward of the engine in each nacelle. Its three major components include a constant speed drive, an accessory gearbox, and an all-attitude oil reservoir. Input power from the engine is transmitted to the ADS through a reduction gearbox on the engine and a flexible drive shaft. At the ADS, a constant speed drive unit converts the variable shaft speed to a constant rotational speed to power the AC generator. Two hydraulic pumps and a fuel circulating pump are also mounted on the ADS gearbox. The two hydraulic pumps supply power for the (A and L) or (B and R) hydraulic systems. The fuel circulating pump supplies fuel to the aircraft heat sink system. The speeds of these pumps vary directly with engine RPM.</p>
<p>The ADS is lubricated by an independent dry sump system with its own pump, using oil from an all-attitude reservoir. The reservoir is pressurized with nitrogen gas from the aircraft LN<sub>2</sub> system and supplies oil to the accessory gearbox, the constant speed drive, and the AC generator regardless of flight attitude. (Loss of the LN<sub>2</sub> supply to the ADS does not affect ADS operation.) The oil is cooled by circulation through a fuel-oil heat exchanger which is part of the heat sink system. Reservoir capacity is approximately 8 quarts.</p>
</section>
<section>
<h3>External Starter System</h3>
<p>An external starting unit is required for ground starts. This may be a compressed air supply, a self-contained gas engine cart, or a multiple air-turbine cart. The output drive gear of either cart connects to a starter gear on the main gearbox at the bottom of the engine. There are no aircraft controls for this system. It is turned on and off by the ground crew in response to instructions from the pilot.</p>
</section>
<section>
<h3>Chemical Ignition (TEB) System</h3>
<p>Triethylborane (TEB) is used for starting ignition of main burner and afterburner fuel. Catalytic igniters attached to the afterburner flame holders tend to maintain afterburner operation after initial ignition.</p>
<p>A 600 cc (1-1/4 pint) TEB storage tank is installed on each engine. The tanks are pressurized with nitrogen gas prior to flight to provide inerting and operating pressure. Special handling procedures are required for TEB as it will burn spontaneously with exposure to air above -5°C. The TEB tank is cooled by main burner fuel flow. A rupture disk is provided for each tank which will allow vaporized TEB and nitrogen gas to be discharged through the afterburner section if tank pressure exceeds a safe level. No indication of TEB tank discharge is provided to the flight crew.</p>
<p>At least 16 metered TEB injections can be made with one full tank of TEB. The system is controlled by engine fuel pressure signals while the engine is rotating. Throttle advancement from OFF to IDLE provides main burner ignition, and from Military into the AFTERBURNER range provides afterburner ignition. Main burner ignition occurs almost immediately during an air start with the engine windmilling. The time required to obtain afterburner ignition is a function of the afterburner fuel manifold fill time, (up to three seconds at sea level and seven seconds at altitude).</p>
<h4>Igniter Purge Switch</h4>
<p>An IGNITER PURGE toggle switch is located on the pilot's right instrument side panel. When the switch is held in the up position, a solenoid-operated valve supplies fuel-hydraulic system pressure to the chemical ignition system dump valve if the engine is rotating. This allows the TEB to be dumped into the afterburner section. While dumping, engine speed should be above 5000 RPM to avoid afterburner liner damage. The purge switch must be actuated for at least 40 seconds to dump a full load of TEB. At the end of the dump period, the switch should be released and re-cycled to clean out the lines. Electrical power for purging is furnished from the essential DC bus through the IGN PURGE circuit breaker on the pilot's left console.</p>
<figure id="fig-1-12">
<img src="images/1-12.jpg" alt="" />
<figcaption>Figure 1-12: Center Instrument Panel - Forward Cockpit</figcaption>
</figure>
<table border="1">
<tbody>
<tr>
<td>
<p>1</p>
</td>
<td>
<p>Spike Position Indicator</p>
</td>
</tr>
<tr>
<td>
<p>2</p>
</td>
<td>
<p>Pusher/Shaker Switch</p>
</td>
</tr>
<tr>
<td>
<p>3</p>
</td>
<td>
<p>Forward Bypass Position Indicator</p>
</td>
</tr>
<tr>
<td>
<p>4</p>
</td>
<td>
<p>Compressor Inlet Pressure Gage</p>
</td>
</tr>
<tr>
<td>
<p>5</p>
</td>
<td>
<p>RSO Bailout Switch</p>
</td>
</tr>
<tr>
<td>
<p>6</p>
</td>
<td>
<p>Temperature Indicator</p>
</td>
</tr>
<tr>
<td>
<p>7</p>
</td>
<td>
<p>RSO Ejected Indicator Light</p>
</td>
</tr>
<tr>
<td>
<p>8</p>
</td>
<td>
<p>Drag Chute Handle</p>
</td>
</tr>
<tr>
<td>
<p>9</p>
</td>
<td>
<p>Left Inlet Unstart Light</p>
</td>
</tr>
<tr>
<td>
<p>10</p>
</td>
<td>
<p>Compressor Inlet Temperature Gage</p>
</td>
</tr>
<tr>
<td>
<p>11</p>
</td>
<td>
<p>Airspeed - Mach Meter</p>
</td>
</tr>
<tr>
<td>
<p>12</p>
</td>
<td>
<p>Nosewheel Steering Engaged Light</p>
</td>
</tr>
<tr>
<td>
<p>13</p>
</td>
<td>
<p>KEAS Warning Light</p>
</td>
</tr>
<tr>
<td>
<p>14</p>
</td>
<td>
<p>Air Refuel Switch</p>
</td>
</tr>
<tr>
<td>
<p>15</p>
</td>
<td>
<p>Air Refuel Ready - Disc Push-button and Light</p>
</td>
</tr>
<tr>
<td>
<p>16</p>
</td>
<td>
<p>Angle of Attack Indicator</p>
</td>
</tr>
<tr>
<td>
<p>17</p>
</td>
<td>
<p>Standby Attitude Indicator</p>
</td>
</tr>
<tr>
<td>
<p>18</p>
</td>
<td>