NBSIR 76-10516^)

A Prototype Automated Test

System for J52 Engine Fuel

Controls

Part 1 . Hardware Systems

Summary

David W. Baker*

Alfred L. Koenig**

Victor Brame, Jr.*

Institute for Basic Standards*

Institute for Computer Sciences and Technology**

April 1976

Final

Prepared for Naval Air Systems Command

Department of the Navy

Washington, D. C. 20361

NBSIR 76-1051

A PROTOTYPE AUTOMATED TEST

SYSTEM FOR J52 ENGINE FUEL

CONTROLS

PART1. HARDWARE SYSTEMS

SUMMARY

David W. Baker*

Alfred L Koenig**

Victor Brame, Jr.*

Institute for Basic Standards*

Institute for Computer Sciences and Technology**

April 1976

Final

Prepared for Naval Air Systems Command

Department of the Navy

Washington, D. C. 20361

c^T OF ^

U.S. DEPARTMENT OF COMMERCE. Elliot L. Richardson, Secretary

James A. Baker. Ill, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Acting Director

ABSTRACT

Hardware subsystems are described which have been developed by NBS

and added to a manually controlled test stand, CID Model 15730, and

which together comprise the test system. Digital computer control

is used which incorporates a vendor supplied real time software

operating system, extended and adapted to the hardware subsystems

by NBS. When applications software is complete, the system will

be suitable for production testing of J52 engine fuel controls.

Test parameters under computer control are shaft speed, burner air

pressure and compressor inlet pressure, along with systems used solely

for measurement of fuel control discharge and supply flowrates and

eight fuel control pressures. The operator controls the test through

a subsystem equipped with a CRT, a teletypewriter, and a set of backlighted display lamps. The hardware and software systems have been

designed for multistand control, and hardware requirements for control

of up to five stands by one computer are discussed briefly.

Key Words: Automated test equipment; Automated test equipment for

jet engine fuel controls; Digital computer controlled test

equipment; Jet engine fuel control test equipment; Minicomputer

applications; Minicomputer controlled test equipment; Supervisory

control
CONTENTS

Page

1. Introduction 1

2. Hardware Systems Overview 2

3. Systems Design 5

3.1 NC Speed Control 5

3.2 PB Pressure Control 8

3.3 PT2 Pressure Control 11

3.4 WF and I«7T Measuring Systems 11

3.5 Pressure Measuring Systems 14

3.6 Operator/Machine Interaction 14

3.7 Test Stand Control and Power Flow 20

3.8 Purge Air System 22

4. References 25

Appendix A. Five Stand Design .26

Appendix B. Primary Hardware Components 28

Appendix C. Glossary 31

- ii -
FIGURES

1. J52 System Hardware Configuration 3

2. CID Model 15730 Test Stand Console With Prototype 4 Operator Control/Display Panel

3. J52 Computer System 5

4. NC Speed Control 7 5. PB Pressure Control 9

6. PT2 Pressure Control 12

7. WF and WT Measuring Systems 13

8. Pressure Measuring Systems 15

9. Operator Control/Display Panel 15

10. CRT and Lamp Display Panel IP

11. Pendant Station for Step Motor Manual Control 19

12. Test Stand Power Flow and Control Sequence 21

13. Purge Air Circuit and Interlock Locations 23

14. Power Flow to Automated Systems, Safety Interlocks 24

Control

15. J52 System Auxiliary Racks 1 and 2 27

- iii -
ACKNOWLEDGEMENTS

The prototype test system has been developed and built under a program

sponsored and supported by the Department of the Navy, Naval Air Systems

Command, Code AIR5343, headed by Mr. Thomas Lyle. Participation and

assistance rendered by Mr. William Haight, NBS Division 213.06, and

Mr. John Hazzard, 213.04, in design of the Operator Panel; by Mr. Kenneth

Benson and Mr. James Melvin, 213.06, during installation of the test

stand and automation components; by Mr. Louis Palombo and Mr. James

McNally, 650.01, for computer interface construction and hardware systems

cabling; and by Miss Pat Beall, 213.06, and Mrs. Susanne Bussard, 213.00,

for manuscript typing is gratefully acknowledged.

- iv -
1. INTRODUCTION

A prototype automated test system has been developed and built at tlu> National Bureau of Standards for use in the adjustment and calibration

of J52 engine fuel controls. A manually operated production test stand,

installed and operational at NBS, has been put under digital computer

control by the addition of hardware subsystems, and by extension and

adaptation of real-time operating system (RTOS) software. The stand.

Model CID 15730, was built by Cox Instruments Division of the Lynch

Corporation* and RTOS was supplied by Interdata Incorporated, the computer

vendor. To complete the software system, application software suitable

for production testing of J52 engine fuel controls will be needed. Such

software has been designed but has not been written. Earlier documentation

[1]** includes RTOS as extended and adapted by NBS and the design of the

necessary application software.

The purpose of this report is to summarize the hardware systems in this

prototype system from a general functional and design point of view. Some

estimates of performance under computer control are included and these are subject to verification when complete application software is available.

Design details covering the computer interfacing and description of the

computer system configuration are given in [2]. Automated systems' electrical

hydraulic and pneumatic circuitry; stand power distribution and control

circuit diagrams; subsystem design and wiring diagrams; interconnecting

cabling lists and parts lists are given in [3] along with a list of hardware

vendor technical manuals for the components used. Design of components and

assemblies with complete mechanical detail design and dimensioning is not

presented. A glossary is included herein to define special terms. As

requested by the sponsor, the computer system and software systems have

been designed and configured for control of up to five stands. See Appendix

A and [1]. This report together with [2] and [3] are intended to serve as basic documents for duplication of this prototype system or for addition

of hardware subsystems to control additional test stands.

Two important fuel control test parameters presently remain manual control

parameters. These are power lever angle PLA, and compressor inlet temperature

TT2 , For a fully effective automated test system, these too should be automated.

Automation of PLA should be straight forward, using for example, step motor

control to position the input shaft on the fuel control. However, to speed

up present testing, automation of TT2 would logically require simulating the

output of the present fuel control temperature bulb system, a slow responding

system requiring several minutes to settle at the desired setpoint value.

This simulation would involve a change in test philosophy and test procedure

for this control, along with special hardware designed to mate to the fuel

control. Such an approach, however, is not new to the fuel control test

industry, and should be investigated in this program.

* Certain commercial equipment or products are identified in this report

in order to adequately specify the design. In no cases does such

identification imply recommendation or endorsement by the National

Bureau of Standards, nor does it imply that the material identified

is necessarily the best available for the purpose.

** Numbers in brackets refer to references given at the end of this document

- 1 -
The role automated testing is likely t industry, along with brief discussions

functions of fuel controls are given e

o play in the fuel control calibration

of present testing techniques and

Isewhere, e.g. [4] and [5].

2. HARDWARE SYSTEMS OVERVIEW

Figure 1 shows the prototype hardware system connected to the fuel control

and pertinent test stand systems. Test parameters which are under computer

control are NC speed, PB pressure, and PT2 pressure, with additional systems

for measurement of fuel control supply flow or total flow WT, metered fuel

flow WF and various fuel control pressures and differential pressures. All

parameters are read out as needed one at a time through a multiplexer system

and preset counter, both under computer control. The blocks denoted PLA

Input System and TT2 Input System are planned for future expansion and are not included in the present prototype system, as noted above. These are believed necessary for a fully effective automated test system.

The Operator Panel is equipped with a set of display lamps which indicate

hardware and software systems status, a cathode ray tube (CRT) display

system dedicated to fuel control test information including display of

required values, operator inputs and test results, and a teletypewriter

(TTY) for operator command inputs and hardcopy printout. Through the test

stand relays, the computer can turn off the stand (stand emergency stop)

and it can control the stand between conditions of drive stopped and stand

systems unpressurized to stand systems fully pressurized and operative.

The Pendant Station is used to manually control step motors in the various

input systems.

Stand systems controlling the total flow schedule, boost pressure level,

nozzle discharge pressure schedule, and fuel temperature remain unchanged.

Indirect control of total flow WT is implemented through direct control of

NC speed. PLA position and TT2 temperature (bath system) are currently

manual parameters. Automation of TT2 would logically use a simulation

approach positioning the fuel control temperature sense servo piston directly

in place of the temperature (bulb) sensing system. Transfer between stand

and automated systems is a manual operation.

The blocks at the top of Figure 1 show the computer system, defined to

include the processor, a line printer, a paper tape reader and punch unit,

a teletypewriter, a fixed head disc data storage unit, a clock module, and

the device interfaces. This system is believed adequate for the end user who would be primarily concerned with changes in test specifications only,

and who would be supplied with the software systems already programmed as

a turn- key job.

Figure 2 shows the test stand console with the prototype Operator Panel

located at the right, with the fuel control mounted on the stand drive

pad at left center, and with the stand controls and instrumentation

normally used by the operator located between these two items.

- 2 -
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- 4 -
Figure 3 shows the computer system (from left to right) with the line printer;

the teletypewriter; the processor with its display panel, the high speed

paper tape reader/punch unit, and the disc all housed in CPU Cabinet 1; and the preset counter, V/F converters, and a card file with interface

boards all housed in CPU Cabinet 2.

The computer system consists of an Interdata Model 70 processor with

64K bytes of core memory, a Pacific Micronetics Model 1-011-12B fixed

head disc with 2.1 megabytes capacity, a Centronics Model lOlA printer

rated at 165 characters/sec, a Teletype Model KSR-37 TTY rated at

15 characters/sec, and an Interdata Model 7-413 high speed paper tape

reader/punch unit rated to read 300 and punch 63 characters per second.

Additional details for the computer system and test stand automation

systems components are listed in Appendix B.

Except as noted below, the prototype system has been assembled using

primarily off-the-shelf components. The device Interfaces for the

display lamps, the CRT, the TTY, the Test Stand Relays, the Dual

Multiplexer and the Counter were designed and constructed at NRS,

Division 650.01, and the signal conditioners for NC and WT signals in

213.06. The NC, PB and PT2 step motor Interfaces were purchased from

Technology Incorporated from designs used in the Navy TF30 fuel control

test stand automation program, and the disc Interface was purchased

from Pacific Micronetics. The PB Input regulator is a modified design

by Moore Products.

In addition to systems for control and measurement, and for operator

interaction, suitable systems* are needed to ensure safe operation for

all hardware located at the test stand console area, a hazardous location

where hydrocarbon vapors are always present, classified as Class 1, Group

D, Division I in the National Electrical Code (NEC) [6]. All pressure

and flow transducer equipment have been housed in totally-enclosed explosion

proof boxes or purchased in such housings conforming to the NEC. All other

equipment have been located in air purged enclosures in accordance with

the requirements of the NEC. The purge air system added along with the

automation hardware is discussed below.

3. SYSTEMS DESIGN

3.1 NC Speed Control

Figure 4 shows the NC speed input and readout systems, controlling NC

speed under computer control in the range 50 to 4200 rpm, and to zero. For manual stand control, transfer switch item EA 537* is set in the MAN

position, and the operator controls NC through stand console potentiometers

Ell and E19**. For computer control, the transfer switch is set in the

COMP position. NC control will be implemented through applications software.

A supervisory software control loop has been used successfully in similar

systems and is recommended here. This loop starts with reading current

NC through the pulse pickup, followed by calculating the number of motor

* Item numbers with prefixes EA and A refer to components added to the

CID 15730 stand for the automated system, as listed in [2]

** Item numbers with prefix E or no prefix refer to original stand system

components as listed in [7].

_ 5 -

FUEL

CONTROL

MAN/COMP

STAND

SPEED

POTS

Ell, E19

TRANSFER

SWITCH

EA5 37

STAND

VARIABLE

SPEED

DRIVE

E508

PULSE

PICKUP

EA528

AUTOMATED

SPEED POT

EA523B

3f

START

RELAY

CLUTCH, A52 3

IE

NC LIMIT

STEP MOTOR SWITCHES

EA523A EA52 3C

VARIABLE

SPEED

DRIVE

EA52 3

PENDANT

STATION

NC MOTOR

INTERFACE

NC SIGNAL

CONDITIONER

EA504

DUAL

MULTIPLEXER

FREQUENCY

SECTION

PRESET

COUNTER

MULTIPLEXER

INTERFACE

PROCESSOR

MULTIPLEXOR BUS

COUNTER

INTERFACE

FIGURE 4. NC SPEED CONTROL

- 7 -
steps necessary for setting NC to the next desired value. The motor would

then be run in the appropriate direction about 90 percent of this amount,

NC speed would be read again, and the process repeated several times. Thus,

NC would be set in an iterative fashion to within a program-stored tolerance.

Features of this system include counting step motor pulses in hardware,

incorporation of high and low speed limit switches, and incorporation of a pendant station housing controls with which the operator can conveniently

control the NC drive manually along with computer control. The low speed

limit switch is set for zero speed and thus is used for start up and for

control to zero speed.

Under computer control, the time necessary to control to a desired value

to within a tolerance of 1 rpm is estimated should not exceed about 14

seconds for a full scale speed excursion of 4200 rpm, allowing time for

several NC reads and for the settling time of the drive after each motor

run, and using a constant slew rate of about 800 rpm/sec. This slew rate

is set by a manual potentiometer (pot) adjustment on the step motor variable

speed drive system, but is also limited by the individual test stand variable

speed drive characteristics. Although the motor interfaces purchased included

time delay circuitry, drive settling times are best Implemented through

software time delays for each drive as stored in a table of constants called

TASK COMMON. This will result in a more flexible and usable automated

production test system. Manual control of NC with the Pendant Station along

with computer control will result in no speed "bumps". However, transfer

between the stand speed pots and the automated speed pot should preferably

be accomplished at zero speed to avoid possible large step speed inputs

to the stand.

For details concerning programming of NC, see [1], Volume 1, Sections 5,

8.4, 8.7, and 9, Attachments A, B, C and H. Details concerning interface

design are given in [2], and system circuit diagrams are given in [3].

3.2 PB Pressure Control

Automated PB inputs are generated in the range 5 to 300 psia* using the

system shown in Figure 5. Under software control using an approach similar

to NC, a supervisory control loop would be used in which PB is varied by

the step motor driven pressure regulator PB REG, and read out through the

system consisting of the PB transducer, a dedicated DC to frequency (V/F)

converter, the Dual Multiplexer, and the preset counter. Control to a set

point would be accomplished in a iterative fashion, running the step motor

several times with PB reads in between until the desired value is set to

within a programmed tolerance.

To convert to SI units, multiply the pressure psia units by 6.895 to

obtain corresponding pressure in kilopascals absolute.

- 8 -
TRANSFER

VALVE

A501

HIGH

PRESSURE

AIR

SUPPLY

PB

REG

A525

TRANSFER

VALVE

A502

REG

55

VAC

REF

VAC

EXH

FUEL

CONTROL

PB AIR

PILOT

BOOSTER

580

REG

55

LIMIT PIi SWITCHES STEP MOTOR

EA52 5B EA52 5A

PB

TRANSDUCER

SYSTEM

EA512

V/F

CONVERTER 2

EA518

VARIABLE

SPEED

DRIVE

EA525

PENDANT

STATION

PB MOTOR

INTERFACE

PROCESSOR

MULTIPLEXOR BUS

DUAL

MULT IP-LEXER

FREQ. SECTION

PRESET

COUNTER

MULTIPLEXER

INTERFACE

COUNTER

INTERFACE

FIGURE 5. PB PRESSURE CONTROL

- 9 -
Valves A501 and A502, located inside the stand console, transfer PB between

the Ml and manual regulator REG 55 and the automated system. Stand regulator

REC; 568 serves both systems as a pressure reducing regulator for air supply

to the active PB regulator. PB pressure is always fed to stand pilot booster

580 which transmits PB to the back pressure valve in the nozzle discharge

system. Since the exhaust pressure VAC EXH for the motor driven regulator

PB REG varies with PB load, a low pressure regulated input VAC REF is needed

to insure short term stability of the regulated output. This reference

signal is nominally set in the range 1 to 3 psia. The pressure reducing

regulator REG 568 limits forward leakage flow to the load, necessary to ensure PB control at the low end of the range. It senses PB and controls

the pressure differential across PB REG (and REG 55) to about 25 psi.

Limit switches directly connected to the step motor shaft prevent over ranging at both high and low PB pressures, with status signals to the

computer through the PB motor interface. When under computer control,

the stand operator can vary and set PB manually with the Pendant Station.

Under computer control, it is estimated the time to set PB to within a programmed tolerance* through an excursion of 200 psi will not exceed

about 17 seconds. Smaller PB excursions will take less time; for example,

an excursion of 20 psi is estimated would not require more than 6 seconds.

The available slew rate for setting PB is about 20 psi/sec. The control

times allow for several reads of PB and for PB system settling time or lag.

The maximum lag for the prototype system is about 1 second which occurs at

low PB in the range 5 to 10 psia. This lag is due to the time it takes for

air in the PB load circuit between PB REG and the fuel control' to exhaust

to VAC EXH, limited by sonic flow within parts of the regulator itself.

This regulator, Moore Model 40AE450(M66) , was purchased with increased

exhaust flow capacity as modified by Moore Products. A dedicated vacuum

pump, 8 CFM capacity, is used with the PB system to prevent interaction

with the PT2 system. This pump has been added to the stand console system.

Caution

To avoid possible high PB step inputs to the fuel control, transfer

with valves A501 and A502 between the stand PB regulator 55 and the

automated system should occur with the high pressure air supply turned

off.

Detailed information needed for programming PB control is included in [1]

;

see Volume 1, Sections 5, 8.7, and 9, Attachments A, B, C and I. Details

concerning interface design are given in [2] , and system circuit diagrams

are given in [3]

.

* As given in [1], the tolerances are 0.05 psi for PB < 100 psia, and 0.10

for PB >_ 100 psia.

- 10 -
3.3 PT2 Pressure Control

Automated PT2 inputs In the range 1 to 30 psia are generated with the

system shown in Figure 6 with the motorized regulator PT2 REG. This

system is functionally similiar to that for PB control including use

of a supervisory control approach. Minor differences include control

to closer tolerances (to 0.01 psi) , incorporation of a dedicated pressure

reducing regulator REG A538 rather than sharing a reducing regulator with

the stand system, and no requirement for a vacuum reference signal for

PT2 REG. Again, a dedicated vacuum pump, 3.5 CFM capacity, for VAC EXH

is used, isolating the PT2 and PB systems. This is the pump originally

installed in the stand console.

Under computer control, it is estimated no more than about 16 seconds

maximum will be required to set PT2 through an excursion of 20 psi. This

uses a slew rate of about 2.9 psi/sec, as set by manual pot adjustment

on the PT2 variable speed drive system, and allows for similar PT2 system

lags or settling times (about 1.5 seconds in the range 1 to 2 psia).

Smaller PT2 excursions will require less time, for example an excursion

of 2 psi should not require more than about 6 seconds for control to

the set point.

Detailed information needed for programming PT2 control is included in

[1]; see Volume 1, Section 5, 8.7, and 9, Attachments A, B, C and I. Details concerning interface design are given in [2], and system circuit

diagram are given in [3].

3.4 WF and WT Measuring Systems

Discharge flow from the fuel control is measured by the WF Turbine Meter

system as shown on Figure 7. This system consists of a turbine meter

WF METER, a flow straightener section upstream, a section of straight

tubing downstream, and the WF signal conditioner whose output is fed to

the preset counter through the Dual Multiplexer. Measurements of WF can

be made in the range 300 to 11,000 Ib/hr* to an uncertainty not exceeding

0.5 percent of rate. The approach is to determine meter frequency by

measuring the period required for a predetermined number of pulses. In

this way, adequate resolution is obtained in 0.5 second nominal, an interval

sufficient for a steady sample of the (fluctuating) flow, and much less

than the time it would take to measure frequency directly at low flow rates.

The necessary predetermined number of pulses will vary with flow rate and

is first determined by a preliminary, or sample period count taking 0.2

second nominal. Thus, an accurate measurement of WF will require about

0 . 7 second

* To convert to SI units, multiply the flow rate in Ib/hr by 0.4536 to

obtain corresponding kg/hr.

-11 -
LOW PRESSURE

AIR SUPPLY

TRANSFER

VALVE

A503

REG

54

REG

A538

PT2

REG

A524

VALVE

63

FUEL

CONTROL

TRANSFER

VALVE

A504

VAC

EXH

AIR

VENT

REG

54

PT2

PT2

TRANSDUCER

SYSTEM

EA511

LIMIT

SWITCHES

EA524B

PENDANT

STATION

PT2

STEP MOTOR

EA524A

VARIABLE

SPEED

DRIVE

EA524

PT2 MOTOR

INTERFACE

MULTIPLEXER

INTERFACE

DUAL

MULTIPLEXER

FREQUENCY

SECTION

\ PRESET

COUNTER

\ COUNTER

INTERFACE

PROCESSOR

MULTIPLEXOR BUS

FIGURE 6. PT2 PRESSURE CONTROL

- 12 -
FLOW STRAIGHTENER

FUEL FROM

HEAT EXCHANGER 581

WF

METER

EA501

STRAIGHT

TUBING

TO STAND

WF METER 76

WF SIGNAL

CONDITIONER

EA502

WF SIGNAL

CONDITIONER

EA504

FUEL FROM

(FILTER 525

TO

FUEL

CONTROL

WT METER E509

PROCESSOR MULTIPLEXOR BUS

1

DUAL

MULTIPLEXER

FREQUENCY

SECTION

PRESET

COUNTER

COUNTER

INTERFACE

MULTIPLEXER

INTERFACE

FIGURE 7. WF AND WT MEASURING SYSTEMS

- 13 -
Total flow WT, the inlet supply flow rate to the fuel control, is obtained

using the turbine meter item E509 originally installed in the stand. The

meter output signal is connected to the Dual Multiplexer through an added

signal conditioner. In this case, a direct pulse count for 0.5 second

gives sufficient resolution for this measurement. Stand item E512 Control

Unit is shown for reference. WT measurements in the range 1000 to 15,000

Ib/hr to an uncertainty not exceeding 1 percent of rate are made with

this system.

Details for use of the WF and WT meters under software control are given

in [1], Volume 1, Section 9, Attachments B, F (for WF) and G (for WT)

.

Circuit diagrams for these systems are included in [3].

3 . 5 Pressure Measurement Systems

Measurements of burner pressure limiter pressure PC, differential pressures

Dl and D2 , and gauge pressures PI, P2, and P3 are made through the system

as shown on Figure 8. The PC transducer is dedicated to the burner pressure

limiter measurement, but the other transducer systems are shared with various

test parameters as needed.* All of these transducer systems employ a DC

voltage output and share V/F Converter 1 as fed through the Dual Multiplexer.

These transducers are rated at 0.15 percent of range including linearity,

hysteresis and repeatability. Additional information including ranges are given in Appendix B herein. Other signals, variable frequency pulse rates

for NC, PB, PT2, WF, WT and spares are shown for reference purposes. Procedures

for making pressure measurements under computer control are given in [1],

Volume 1, Section 9, Attachments B and I. Circuit diagrams for these systems

are given in [3]

.

3 . 6 Operator/Machine Interaction

The stand operator communicates with the automated test system through

the Operator Control/Display Panel (Op Panel) located at the right hand

side of the stand console as shown on Figure 9, and through the Pendant

station for step motor manual control. The Op Panel contains a teletypewriter (TTY) for command input, and hardcopy printout at 15 characters per

second; a Cathode Ray Tube Display (CRT) system capable of display of 640

characters; and a Display Lamp Panel having 36 displays used for short

messages

.

The CRT system is used for the display of fuel control test information

including test point number, automated test mode, input and observed

parameter data, and message data such as stand operator action or instructions. Utilization of the CRT during test point processing is

discussed in detail in [1], Volume 1, Section 4.10. This system is composed

of a 23- inch size video monitor Electrohome Model EVM-23 and a character

generator Digi-Log Model 209. Characters are approximately 0.5 inch high

* Symbols Dl, D2, PI, P2 and P3 designate automated system hardware only,

and are not fuel control test parameter designations. See [1], Volume

I, Section 9, Attachment A which lists both test parameters and automated

system hardware.

-14 -
i \ i 1 1 1 PC Dl D2 PI P2 P3

EA510 EA5 05 EA506 EA509 EA507 EA508

j

TRANSDUCER SYSTEMS

OPERATOR-PATCHED

D AND P INPUTS

REFERENCE INPUTS

NC, PB, PT2, WF, WT

SPARES (4)

PROCESSOR MULTIPLEXOR

BUS

DUAL

MULTIPLEXER

DC SECTION

V/F

CONVERTER 1

EA517

I

DUAL

MULTIPLEXER

FREQUENCY

SECTION

I

PRESET

COUNTER

I

COUNTER

INTERFACE

MULTIPLEXER

INTERFACE

FIGURE 8. PRESSURE MEASURING SYSTEMS

- 15 -

and each is formed by a 5x7 dot matrix. Sixteen lines of 40 characters

each can be displayed at a maximum of 872 characters/second (9600 baud

data rate, 11 bit code). With nominal software overhead time, about 1 second will be required to fill the screen. The character height affords

easy viewing for the operator at any position in his work area. Controls

for adjustment of screen quality are available behind the lower access

door without power shutdown of the Op Panel or program interruption.

Removal of the front or rear panel does require power shut do\<m, as interlocked through a purge air pressure switch as discussed below. See

Figure 10 for a view of the CRT and Display Lamp Panel with the front

panel removed.

The TTY (Teletype Model KSR-37) is positioned with the keyboard 14 inches

forward of the CRT so that the printed page is easily viewed and to allow

opening of the TTY case. The lever system shown on the left of the TTY

activates a mechanical switch which shuts off TTY power when the case is

opened. The TTY electrical service unit (ESU) is located in the lower

chamber of the Panel.

The Display Lamp Panel (Technology Inc. Model 112) is used to output status

information for automated hardware systems including indicators for purge

air and equipment power; error conditions for the processor, for hardware

I/O, and for illegal stand operator commands; and for status of the parameters

under control, namely NC, PB, PT2, WF, WT, and future PLA and TT2 . Indicated

status includes step motor high and low limits, motor control (running)

status including overshoot indication, and parameter in-tolerance and out-oftolerance status at the set point. Use is made of red, green and yellow

lamps, and on/off and flashing modes. Figure 10 shows the status messages

for this display panel. Detailed specifications on use of this display panel

are given in [1], Volume 1, Section 4.11. All lamps except those indicating

purge air and power status are under program control. Further, all control

and tolerance lamps can be disabled as a group with an added internal switch

in the upper chamber of the Op Panel, an NBS modification. Thus with this

flexibility, production experience and operator preference can be deciding

factors whether or not these two sets of lamps are in use continuously.

Figure 11 shows the Pendant Station for step motor manual control. With

the stand under computer control with the ACJET system, the stand operator

can, at any time, conveniently control each step motor individually except

during those periods when the motor is actually being run under computer

control. . Changing between manual and computer control is bumpless. The

operator selects a parameter (NC, PB or PT2) by a knob switch; the direction

(forward or reverse) through a rocker switch; and then one of three motor

slew speeds or jogs the motor, all through a set of four momentary push

buttons. Slew speeds include FAST, which enables a full scale traverse

ranging from 8 to 10 seconds depending upon parameter selected, a MEDIUM

slew speed ranging from 20 to 30 seconds for full scale, and SLOW, which

normally enables satisfactory control to a setpoint. In addition, the JOG

position enables closer control with discrete numbers of motor pulses output

for each switch actuation. Although not shown on the controls, possible

expansion to include operation of motors for PLA and TT2 control has been

included in the design.

- 17 -

FIGURE 11. PENDANT STATION FOR STEP MOTOR MANUAL CONTROL

- 19 -
This station is mounted on a flexible hose near the center of the stand

console and allows the operator to control these motors from positions

within a reasonably large part of his normal work area. This hose houses

the necessary electrical conductors and also conducts purge air to the

Pendant Station.

3.7 Test Stand Control and Power Flow

A set of computer-controlled relays are used to control the following

stand functions or systems: stand emergency stop, fuel boost pump power,

fuel high pressure pump power, vacuum pumps power, and stand variable

speed drive DC controller power. Also, operation of the fuel control

manual/normal transfer system is similarly under computer control.

Figure 12 depicts power flow for these systems. For manual control of

the test stand, computer control of stand emergency stop through relay

Kl and the purge air interlock through pressure switch PSl are both made

inactive by manual switch FA537 located in the stand electrical control

cabinet, and with no computer control relays Kn energized, all stand

systems are operated normally through stand controls. Pressure switch

PSl, which senses the purge air supply pressure, is the primary interlock

between the test stand and the automated systems when under computer control

since it interlocks with stand relay CRl controlling power to the stand

control circuit.

The computer controlled relays are connected to duplicate the operation

of the stand momentary push button switches and when under computer control,

each relay is actuated momentarily upon receipt of a command byte from the

computer. Thus, stand systems manual stop and start push buttons are always

active and the operator is never "locked out".

Under computer control, power to the stand variable speed drive DC controller

is controlled through the low limit switch on the NC step motor. Thus,

start up must occur from zero speed, duplicating manual stand operation.

To stop the drive alone, NC motor must be driven to the low limit position

under computer control, or the operator must actuate the Vairiable Speed Drive

stop button.

Two pairs of relays, K8 through Kll, control operation of the fuel control

manual/normal transfer system. These are latching type relays duplicating

operation of stand toggle switches. Relays KIO and Kll control power to

the AC and DC power supplies for this system, and K8 and K9 control the

transfer. The latter pair are interlocked to override stand switch E2

position. Thus, computer control overrides manual control, except the

computer cannot de-energize the power supplies should stand toggle switches

E2 or E9 be closed.

Caut Ion

The operator should keep stand switches E2 and E9 in the "off"

position except when needed manually.

Computer software will keep these relays unenergized except when fuel control

manual/normal transfer is needed,

- 20 -
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3 . 8 Purge Air System

All electrical or electronic equipment added to the test stand console

have been installed in accordance with the National Electric Code, i.e.

either housed in totally enclosed explosion proof boxes or located in

purged air enclosures as required in [6]. The pressure and flow transducer

equipment have all been located in explosion proof boxes or purchased

in such housings.

Figure 13 shows the flow circuit through the air purged enclosures and

the physical location of all safety interlock switches. A centrifugal

blower, rated 865 CFM at 6 inches of water, supplies purge air from an adjacent nonhazardous area. Three temperature switches (TS) and four

pressure switches (PS) sense enclosure air temperature and pressure at

the locations indicated. This system operates at pressures considerably

higher than pressures corresponding to 0.1 inch of water column, the

required minimum, principally because pressure switches which operate

satisfactorily at 0.1 inch are generally less available and more expensive.

To avoid excessive pressures in the upper and lower chambers of the Op

Panel, pressure is sensed in the purge air supply line with restrictions

as shown adjusted so that opening either chamber actuates its pressure

switch. Purge air for the TTY flows from the lower chamber of the Op

Panel up through a cable slot passage via a special adaptor box at the rear of the TTY. Mechanical switches (MS) are located at the lower chamber

door and on the TTY cover, both of which can be opened without tools.

Figure 14 summarizes 120V AC power flow to the automated systems hardware

as controlled by the safety interlocks. All control occurs through 12V

DC relays, two of which are the time delays shown. As noted previously,

pressure switch PSl is the primary Interlock between the test stand and

the automated systems. It Interlocks with stand relay CRl controlling

power to the stand control circuit and when under computer control, purge

air must be "on" before the test stand and the automated hardware in the

hazardous area at the stand console can be energized. To allow sufficient

time for purging prior to power up, time delays are used; one dedicated

to the Op Panel TTY, so that opening up the TTY cover for paper adjustment

for example will only power down the TTY, and one dedicated to the CRT/

Displays and the PB/PT2 Motor Box as shown. When a "Fault" occurs (enclosure

open or temperature high) , power is automatically restored only through

the appropriate time delay once the Fault is cleared (trouble corrected)

.

All other automated hardware are powered directly through Auxiliary Racks

1 and 2 located in a nonhazardous area. Detailed power distribution

circuitry is Included in [3].

- 22 -
PURGE AIR

SUPPLY

r

EA53 0

EA531

EA532

EA534

PSl

PS2

PS3

PS4

NON HAZARDOUS

AREA

FLOW

RESTRICTIONS (4)

TS3 EA526

PB/PT2

MOTOR

BOX

PENDANT

STATION

HAZARDOUS

AREA

OP PANEL

UPPER CHAMBER

CRT, DISPLAYS

MSI EA536

TTY

TSl EA52 7A

MS2 EA535

OP PANEL

LOWER CHAMBER

TTY ESU

FIGURE 13. PURGE AIR CIRCUIT AND INTERLOCK LOCATIONS

- 23 -
I

12DVC

SUPPLY

12 0VAC

1

PURGE AIR "ON"

MONITOR WITH PSl,

INTERLOCKS WITH

STAND RELAY CRl

I

TIME

DELAY 2

(TDR2)

TIME

DELAY 1

(TDRl)

MONITOR TTY

PS2, TSl,

MSI AND MS

FAULT

POWER

DOWN

CLEAR

FAULT

TDRl

RESET

MONITOR

CRT/DISPLAYS

PS3 AND TS2

FAULT

POWER

DOWN ^

CLEAR

FAULT , TDR2

RESET

12 0VAC

OP PANEL

TTY ESU

POWER UP

STATUS

TO CPU

STATUS

TO CPU

OP PANEL

CRT/DISPLAYS

POWER UP

120VAC

PB/PT2

MOTOR BOX

POWER UP

MONITOR

PB/PT2

MOTOR BOX

PS4 AND TS3

FIGURE 14. POWER FLOW TO AUTOMATED SYSTEMS, SAFETY INTERLOCKS CONTROL

- 24 -
4 . REFERENCES

1. ACJET, Accessory Calibration for Jet Engine Tuneup , Volumes 1

through 10, William C. Haight and Helen Wood Hawes, National Bureau

of Standards, Washington, D.C. [A software system submitted to

Naval Air Systems Command under the J52 Engine Fuel Control Test

Stand Automation Program, May 21, 1975]

2. A Prototype Automated Test System for J52 Engine Fuel Controls;

Part 2, Computer System Configuration and Interfacing, Alfred L.

Koenig, National Bureau of Standards^

3. A Prototype Automated Test System for J52 Engine Fuel Controls;

Part 3, System Design and Installation, David W. Baker, Alfred L.

Koenig and Victor Brame, Jr., National Bureau of Standards*

4. An Automated Prototype Test System for Aircraft Engine Fuel Controls,

Design and Operating Experience, David W. Baker and Alfred L. Koenig,

National Bureau of Standards, Washington, D.C. 20234, Proceedings

for 13th Annual Technical Symposium, Washington D.C. Chapter Association

for Computing Machinery, June 20, 1974

5. An Automated Tuneup, Calibration of Jet Engine Fuel Controls, William

C. Haight and Helen Wood Hawes, Automatic Support Systems Symposium

for Advanced Maintainability, IEEE, Oct. 30-Nov. 1, 1974. See also

[1], Volume 1, Section 0

6. National Electrical Code, 1971, National Fire Protection Association,

NFPA No. 70

7. Operation and Service Instructions with Parts Catalog for Model

CID 15730 Stand Assembly, Fuel Control Test, Type 84654, Serial

Nos. 130016-1, -2, 8 December 1971, DoD Contract No. NOO-383-71-

C-5576, Cox Instrument Division of Lynch Corporation, Detroit,

Michigan

8. User's Manual, Interdata Incorporated, publication No. 29-261R03

9. Real Time Operating System (RTOS) Reference Manual, Interdata

Incorporated, publication No. 29-240R07

* For additional information, contact the author (s). Work on this document,

in preparation at the publication of NBSIR-76-1051, has been suspended

while changes in this automation program are under consideration by the

sponsor.

- 25 -
APPENDIX A

CONFIGURATION FOR FIVE STAND OPERATION

The computer system has been designed and configured to accommodate up

to 5 automated test stands as follows. With reference to Figure 3, CPU

Cabinet 1 has slots available for 5 CRT Display interfaces and 5 Op Panel

TTY interfaces with sufficient power supply capacity available to handle

the full complement. CPU Cabinet 2 has sufficient room to accommodate

card files and power supplies for up to 5 stands. If the number of stands

automated does not exceed three, Cabinet 2 may also house the electronic

counters and frequency converter equipment, but for four or more stands

a third CPU cabinet will be needed for these items.

The computer multiplexor bus has been regenerated with bus buffers

sufficient to drive the computer peripherals and one set of stand

automation interfaces. When additional stands are automated, one more buffer must be added in CPU Cabinet 1; an expansion chassis slot has

been reserved for this. In Cabinet 2 a card file, complete with bus

buffer and interfaces, is required for each additional stand automated.

Also, additional power supplies will be needed, one for each card file.

Each additional CID 15730 stand automated will require a set of stand

automation devices as listed in Appendix B, item III, along with necessary

housing components including a PB/PT2 Motor Box, a PB/PT2 Transducer Box,

a Resistor Box, an Op Panel enclosure and one each of Auxiliary Racks 1 and 2 (see Figure 15). Other equipment needed include an additional

vacuum pump for the PB system or equivalent capacity if more than one stand served by one pump is desired, and a set of transfer valves for

the PB and PT2 systems are needed. A detailed parts list comprising

a stand automation device set is contained in [3]

- 26 -

APPENDIX B

PRIMARY HARDWARE COMPONENTS

Hardware components listed Include the computer system and components

for one test stand. Each additional test stand requires an additional

set of stand automation devices, item III. Where applicable, device

interface supplier and model number are shown in parenthesis.

Manufacturer and Model

I. A Central Processor Unit (CPU)

with 64k bytes of core memory

with options:

1. Power fail with auto restart

2. Automatic Memory Protect

3. Selector Channel

4. Universal Clock Module

5. Cabinets (two)

1 1 . Peripherals

1. Disc memory, 2.1 M bytes

2. Console teletypewriter, 15

char/sec

3. High-speed paper tape reader,

300 char/sec, and High-speed

paper tape punch, 63 char /sec,

unit

4. Line printer, 165 char/sec

III. Stand Automation Devices:

1. Operator teletypewriter,

15 char/sec

Interdata 70

M70-100

M70-101

M7 0-103

M48-000

M49-004

M49-005 '

Pacific Micronetics 1-011-128

(Progress Electronics Co. of

Oregon, IS 4-10)

Teletype KSR-37

(NBS Design, 650.01, 2/15/73)

Interdata 7-413

(includes interface)

Centronics lOlA

(Interdata M46-202)

Teletype KSR-37

(NBS Design, 650.01, 2/15/73)

- 28 -
10,

Operator CRT display (video

monitor) , and character

generator, 9600 baud

Display lamp p anel, 36 status

message display units

Reed Relay dual multiplexer,

10 channels for DC inputs

10 channels for pulse rate inputs

Preset counter, 5 digits

DC Voltage to frequency

converters (2 each)

Test stand control relay unit,

12 relays under computer control

Stepping motors with variable

speed drives, for NC speed, and

PB and PT2 pressure input systems

Potentiometer, 2000 ohms

for NC input system

Pressure regulators for

PB and PT2 input systems

Electrohome EVM-23,

Digl-Log 209

(NBS Design, 650,01, 5/3/73)

Technology Inc. 112

(NBS Design, 650.01, 10/21/74)

NBS Design, 650.01, 10/31/73

(includes interface)

Eldorado 1411

(NBS Design, 650.01, 11/9/73)

Anadex DF-100

NBS Design, 213.06, 7/15/74

(NBS Design, 650.01, 9/13/74)

USM Responsyn HDM-150-1600-8

1 each for NC and PT2

HDM-1600-800-4 , 1 for PB

(Technology Inc. 71E45572)

Beckman Helipot 7603

Moore Products 40AE450(M66)

1 for PB

Models 44-50 and 40AE50

1 each for PT2

11. Transducers for Data Acquisition

Parameter

WF

WT

NC

PB

Instrument

Turbine meter, 0.5

to 65 gpm; signal

conditioner and flow

straightener

Turbine meter,

5.0 to 50 gpm; and

signal conditioner

Pulse pick up; and

signal conditioner

Pressure transducer

0-300 psia,

and servo amplifier

Manufacturer and

Model

Cox Instrument ANC-16;

104-026 and 60043-16

Cox Instrument AN-16-2;

NBS Design, 213.06, 2/26/74

Electro 3045A;

NBS Design, 213.06, 2/26/74

Bell and Howell

4-332-0168

1-169

- 29 -
Parameter

PC

PT2

Dl

D2

PI

P2

P3

PLA

TT2

Instrument

Pressure transducer

0-300 psia

Pressure transducer

0-50 psia

Pressure transducer

0-100 psid

Pressure transducer

0-200 psid

Pressure transducer

0-1000 psig

Pressure transducer

0-1000 psig

Pressure transducer

0-200 psig

Future

Future

Manufacturer and

Model

Rosemount

1107A5AIF,A

Bell and Howell

367667-0100

Rosemount

1151DP6A12MB

Rosemount

1151DP7A12MB

Rosemount

1151GP8A12MB

Rosemount

1151GP8A12MB

Rosemount

1151GP7A12MB

12. Cabinets and Housings

Auxiliary Racks 1 and 2

Operator Control/Display Cabinet

PB/PT2 Motor Box

PB/PT2 Transducer Box

Resistor Box

Emcor, ESQ Series,

Frame No. SFR 127A

Electronic Enclosures

NBS Design, 213.06,

1/24/74

Hoffman

A-363012LP

Killark

XB-12168

Adalet

XlF-030903

- 30 -
APPENDIX C

GLOSSARY AND SYMBOLS

Sjonbols are given where used, and synonyms, symbols and alternate names are cross referenced.

Symbol

ACJET ' Accessory Calibration for Jet Engine Tuneup, the

acronjmi given to the software system designed and

generated for this application [1]

APPLICATIONS SOFTWARE

The programs created and/or tailored to process

the requirements of a specific application. In

the ACJET system, these programs include: (1) the

application user tasks through which all test stand

control, data acquisition and data output occurs,

and all fuel control test requirements are met;

(2) the test executive which interfaces between

the operating system RTOS and user application

tasks, and which is primarily charged with

processing test stand operator inputs; (3) the

data base management tasks, since data base

organization is applications oriented; and (4)

the test stand automation device test programs.

AUXILIARY RACK 1, 2 • • • AUX RACK 1, 2 • •

•

Designated cabinets housing stand automation

hardware components.

BOOST PRESSURE

Stand fuel pressure, approximately 30 psig, generated

by a centrifugal pump and needed to assure a positive

pressure at the high pressure pump inlet.

BURNER PRESSURE PB

Air pressure signal fed to the fuel control which

simulates air pressure at the engine compressor

discharge/burner section.

- 31 -
Symbol

BURNER PRESSURE LIMITER PRESSURE PC

The fuel control burner pressure signal which actuates

the PB limiter. In the J52 engine, when the total

burner case differential pressure (PB - ambient pressure)

exceeds a preselected maximum, the PB signal to the

control burner pressure sensor assembly is reduced by

bleeding through the limiter valve to ambient pressure,

resulting in a reduction in fuel flow and engine speed

which prevents combustion chamber pressure from

approaching the maximum safe value.

CARD FILE

Chassis purchased from Technology Incorporated (TI)

to house stand automation device interfaces purchased

from TI.

CATHODE RAY TUBE DISPLAY SYSTEM CRT

A system for displaying alphanumeric information on the screen of a cathode ray tube. The system consists

of a character generator, a video monitor and an interface to the processor.

CENTRAL PROCESSOR UNIT CPU

That portion of the computer system which responds to

a sequence of instructions for arithmetic and logical

processing of data and for controlling or responding

to external devices.

CLOCK MODULE LFC

PFC

The computer system peripheral which includes a line

frequency clock used to provide time of day information

and a precision interval clock which may be used as an interval timer.

COMPRESSOR DISCHARGE PRESSURE PB

See BURNER PRESSURE.

COMPRESSOR INLET AIR TEMPERATURE TT2

Liquid bath temperature which simulates air temperature

at the engine compressor inlet sensed by the fuel control

TT2 bulb.

COMPRESSOR INLET PRESSURE PT2

Air pressure signal fed to the fuel control which

simulates air pressure at the engine compressor inlet.

- 32 -
COMPRESSOR INLET TEMPERATURE

See COMPRESSOR INLET AIR TEMPERATURE

COMPUTER SYSTEM

The system comprised of the CPU and its display panel,

the console teletypewriter, the fixed head disc, the

line printer, the high speed paper tape reader/punch

unit, and the device interfaces.

COMPUTER SYSTEM CABINET 1, 2, • •

• Designated cabinets housing computer system components,

and certain stand automation hardware components

including the electronic counter(s), and V/F converter(s

[CPU Cabinet 2

• •

• ]

CONTROL DRIVE SPEED

See FUEL CONTROL SHAFT SPEED.

CPU, see CENTRAL PROCESSOR UNIT.

CPU CABINET 1, 2 • • • See COMPUTER SYSTEM CABINET 1, 2 •••

CRT, see CATHODE RAY DISPLAY SYSTEM.

DC TO FREQUENCY CONVERTER

The electronic unit which converts variable DC voltage

level to a nominally proportional variable frequency

pulse rate.

DEVICE CONTROLLER

See INTERFACE.

DEVICE INTERFACE

See INTERFACE.

DISC MEMORY

A bulk data storage device consisting of a rotating

disc surfaced with a magnetic material. Data is stored

on the surface as small magnetized areas arranged in

circular tracks around the disc. Data on a given

track is written or read sequentially as the disc

rotates.

DISCHARGE FLOWRATE

See FUEL CONTROL DISCHARGE FLOWRATE.

DISPLAY LAMPS

See DISPLAY LAMP PANEL.
Symbol

DISPLAY LAMP PANEL

A back-lighted lamp assembly dedicated to status

indication for automated parameters and hardware, > and for error conditions for the processor and for

operator command input.

DISPLAYS

See DISPLAY LAMP PANEL.

DUAL DC/ FREQUENCY MULTIPLEXER SYSTEM

The portion of the prototype measurement system

consisting of a dual multiplexer and a DC to

frequency converter. One section of the multiplexer

is used to switch DC signals to the converter. The

other multiplexer section is used to switch AC signals,

including the converter output, to the preset counter.

DUAL MULTIPLEXER

A device with two separate but interdependant reed

relay switching units. Each unit connects multiple

inputs, one at a time, to a common output.

ELECTRICAL SERVICE UNIT ESU

A unit supplied with each teletypewriter consisting

of a chassis containing electronic modules and power

supplies necessary for controlling all the functions

of the keyboard and typing unit.

ESU, see ELECTRICAL SERVICE UNIT.

EXPLOSION PROOF BOX OR ENCLOSURE

A totally enclosed box, normally containing electrical

or electronic equipment, constructed to withstand an explosion or combustion of a hazardous air/vapor mixture.

Such boxes are normally of heavy construction and include

mating closure surfaces sufficiently large to quench any

products of combustion escaping to the outside world.

FUEL CONTROL

The jet engine accessory which meters or schedules fuel

flow to the engine burners as required for the engine

to deliver necessary thrust. Such thrust is dictated

by the position of the pilot's power lever in the cockpit

and by particular operating conditions of the engine,

normally shaft speed, burner pressure, and compressor

inlet air pressure and temperature.

- 34 -
Symbol

FUEL CONTROL DISCHARGE FLOWRATE WF

The metered fuel flowrate discharging from the fuel

control and flowing to the engine burners.

FUEL CONTROL MANUAL/NORMAL TRANSFER

The process within the (J52 engine) fuel control whereby

fuel control metering is transferred between two states,

namely

Normal - in which the metering functions are all

automatic except for PLA input, and

Manual - in which the metering is performed

primarily through PLA input, with

automatic compensation through PT2

only

Usually, the pilot transfers to Manual only during an emergency or when the Normal system malfunctions.

FUEL CONTROL SHAFT SPEED NC

Input shaft speed from the test stand variable speed

drive which simulates engine accessory drive input.

FUEL CONTROL SUPPLY FLOWRATE WT

The fuel flowrate entering the fuel control from the

test stand high pressure supply system. The engine

high pressure fuel pump is simulated by scheduling

and controlling WT as a function of NC speed.

HIGH SPEED PAPER TAPE READER/PUNCH UNIT (Reader) HSPTR

The computer system peripherial which retrieves/ (Punch) HSPTP

stores data on paper tape.

HSPTP; HSPTR, see HIGH SPEED PAPER TAPE RF.ADER/PUNCH UNIT.

INLET BULB TEMPERATURE TT2

See COMPRESSOR INLET AIR TEMPERATURE.

INTERFACE

Electronic circuitry necessary to provide electrical

and logical compatibility between the computer processor

and an external device.

LFC, see CLOCK MODULE.

LINE PRINTER LP

The high speed printing device to which the processor

transmits all characters of a line as a unit.

LP, see LINE PRINTER.

- 35 -
MANUAL CONTROL PENTANT STATION

See PENDANT STATION.

METERED FUEL FLOW

See FUEL CONTROL DISCHARGE FLOWRATE.

MOTOR BOX

An explosion proof or air-purged enclosure in which one

or more step motors are mounted and housed

Kn, see TEST STAND RELAYS,

MULTIPLEXER

The electronic unit or circuitry through which data

from several sources is selected to be transferred

over a common channel to a device that processes or stores the data. The channel may be a single line

or a group of lines.

MULTIPLEXOR BUS (Interdata term)

The channel through which the processor communicates

with external devices. The channel consists of

16 bi-directional data lines, 8 control lines, 5

test lines, and an initialization line.

MUX, see MULTIPLEXER.

MUX BUS, see MULTIPLEXOR BUS.

NC, see FUEL CONTROL SHAFT SPEED.

NOZZLE DISCHARGE SYSTEM

The system of restrictions and valves in the fuel

control discharge circuit of the test stand console

which simulates the engine burner nozzles, scheduling

control discharge pressure as a function of flowrate

WF.

OP PANEL, see OPERATOR CONTROL/DISPLAY PANEL.

OPERATING SYSTEM

A computer program which handles all the housekeeping

or overhead tasks within a computer so that programs

can be as independent from hardware details as possible.

The operating system also sets standard conventions so that programs are compatible with one another [8]

- 36 -
OPERATOR CONTROL/DISPLAY PANEL

The primary device through which the stand operator

communicates with the automated test system. This

unit contains a TTY for command input and hardcopy

printout, a CRT, and a display lamp panel.

OPERATOR PANEL

See OPERATOR CONTROL /DISPLAY PANEL.

OS, see OPERATING SYSTEM.

PENDANT STATION

The device through which the operator manually controls

individual step motors for parameters NC, P^ and PT2,

and future FLA and TT2

PB, see BURNER PRESSURE.

PC, see BURNER PRESSURE LIMITER PRESSURE.

PFC, see CLOCK MODULE.

PLA, see POWER LEVER ANGLE.

POT

Short form for potentiometer.

POWER LEVER ANGLE

The angular shaft position input to the fuel control

which simulates the aircraft pilot's power lever command.

PRESET COUNTER

An electronic counter capable of having its counting

mode and count time interval (pre) set under computer

control

PRESSURE REDUCING REGULATOR

A pressure regulator whose function is to throttle

or reduce pressure in a fluid line.

PRESSURE REGULATOR

A flow device which produces a controlled output

pressure in the range set by the supply and exhaust

pressures and as a function of an input reference

(force) . Inputs include a mechanically loaded spring

and /or a pressure signal.

- 37 -
Symbol

PROCESSOR CPU

See CENTRAL PROCESSING UNIT.

PT2, see COMPRESSOR INLET PRESSURE.

PULSE PICKUP

A magnetic type transducer which generates electrical

pulses when operating In a variable reluctance magnetic

circuit; used In this system together with a spur gear

on the NC speed shaft to generate the NC speed signal.

PURGE AIR

Air containing no hazardous vapors supplied at slight

positive pressure to a box or enclosure, normally

containing electrical or electronic equipment, located

In a hazardous environment. With normal leakage, no hazardous vapors accumulate In the box and a safe

operating environment is preserved.

READER/PUNCH (Reader) HSPTR

See HIGH SPEED PAPER TAPE READER PUNCH UNIT. (Punch) HSPTP

RESISTOR BOX

An explosion proof or air purged enclosure housing

certain pressure transducer load resistors.

RTOS

A real time operating system supplied by Interdata

modified by NBS and adapted to hardware components

used in this application. This system provides for

Interleaving the execution of a number of programs

while still being responsive to the occurrence of

real time events [9]

SPEED NC

See FUEL CONTROL DRIVE SPEED.

STAND

See TEST STAND.

STAND CONSOLE

See TEST STAND CONSOLE.

STAND CONTROL CABINET

See TEST STAND ELECTRICAL CONTROL CABINET.

STAND EMERGENCY STOP

The test stand console control used to de-energlze

the stand systems simultaneously.

- 38 -

i
Symbol

STAND VARIABLE SPEED DRIVE

The test stand subsystem which generates NC speed

drive, including a DC motor driven at variable

speed and the necessary controller electronics

including speed feedback using a DC tachometer.

STEP MOTOR

A precision rotary, bidirectional positioning device

which is driven by electrical pulse inputs. The

output shaft position varies exactly in proportion

to the number of input pulses in incremental angular

steps.

STEP MOTOR DRIVE VSD

See STEP MOTOR VARIABLE SPEED DRIVE.

STEP MOTOR VARIABLE SPEED DRIVE VSD

Refers to terminology used by Responsyn (USM

Corporation) to denote the drive and control electronics

unit generating step motor pulses. This electronics

unit involves a manual pot adjustment to vary motor

pulse or slew rate.

STEPPING MOTOR

See STEP MOTOR.

TELETYPE TTY

See TELETYPEWRITER.

TELETYPEWRITER TTY

A data terminal capable of sending and receiving

alphanumeric information. It includes a typing

or printer unit, and a keyboard unit.

TEST STAND

The assembly of equipment used to flow test jet engine

fuel controls. It provides means to simulate and set

engine operating conditions, and instrumentation to

measure input and output parameter values. The primary

parameters include NC, PB, PT2, TT2, WF, WT and various

pressures and differential pressures.

TEST STAND CONSOLE

The part of the test stand containing the fuel flow

circuitry, involving the supply and nozzle discharge

systems, the actuator elements for simulating the

engine conditions, the parameter measuring instruments,

and the mounting pad for the fuel control. The console

is always located in a hazardous environment for liquid

hydrocarbons, as classified by the National Electric

Code.

- 39 -
Symbol

TEST STAND ELECTRICAL CONTROL CABINET

The part of the test stand containing components such

as the controller for the variable speed drive system,

motor starter relays, and electronic control units and

power supplies. This cabinet is always located in a nonhazardous location.

A set of relays under computer control with which

the following stand functions or systems are controlled:

stand emergency stop, fuel boost pump power, fuel high

pressure pump power, vacuum pumps power, and stand

variable speed drive DC controller power. Also,

operation of the fuel control manual/normal transfer

system is under computer control through relays in

this set. Letter "n" denotes relay number.

TOLERANCE

The assigned value which establishes the range to which

an input parameter is controlled at its setpoint. For

example, for a setpoint of 50, control to within the

range 49.95 to 50.05 would satisfy test requirements

where 0.05 is the assigned tolerance.

TOTAL FLOW WT

See FUEL CONTROL SUPPLY FLOWRATE.

TRANSDUCER BOX

An explosion proof or air purged box housing one or more transducers.

TT2, see COMPRESSOR AIR INLET TEMPERATURE.

TTY, see TELETYPEWRITER.

VARIABLE SPEED DRIVE

A system capable of controlled operation over a range

of speeds, between minimum and maximum RPM.

TEST STAND RELAYS Kn

V/F, see DC TO FREQUENCY CONVERTER

VOLTAGE TO FREQUENCY CONVERTER

See DC TO FREQUENCY CONVERTER.

V/F

VSD, see STEP MOTOR VARIABLE SPEED DRIVE.

WF, see FUEL CONTROL DISCHARGE FLOWRATE.

WT, see FUEL CONTROL SUPPLY FLOWRATE.

USCOMM-NBS-DC - AO -
U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 76-1051

2, Gov't Accession

No.

3. Recipient's Accession No.

r4. TITLE AND SUBTITLE

A Prototype Automated Test System for J52 Engine Fuel

Controls

1 Part 1. Hardware Systems Summary

5. Publication Date April 1976

6. Performing Organization Code

7. AUTHOR(S^

David W. Baker, Alfred L. Koenig, and Victor Brame, Jr.

8. Performing Organ. Report No. NBS 213,06

9. PERFORMING ORGANIZATION NAME AND ADDRESS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2130462

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Naval Air Systems Command

Department of the Navy

Washington, D.C. 20361

13. Type of Report & Period

Covered

Final

14. Sponsoring Agency Code

NAVATT?

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual stxmmary ol most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.)

Hardware subsystems are described which have been developed by NBS and added to a manual controlled test stand, CID Model 15730, and which together comprise the test

system. Digital computer control is used which incorporates a vendor supplied real

time software operating system, extended and adapted to the hardware subsystems by

NBS. I-Then applications software is complete, the system will be suitable for

production testing of J52 engine fuel controls. Test parameters under computer

control are shaft speed, burner air pressure and compressor inlet pressure, along

with systems for measurement of fuel control discharge and supply flowrates and

eight fuel control pressures. The operator controls the test through a subsystem

equipped with a CRT, a teletypewriter, and a set of back-lighted display lamps.

The hardware and software systems have been designed for multistand control, and

hardware requirements for control of up to five stands by one computer are discussed

briefly.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only tfie first letter of Oie first key word unless a proper name; separated by semico/ons; /Automated test equipment? Automated test equipment for jet

engine fuel controls; Digital computer controlled test equipment; Jet engine

fuel control test equipn^nt^ Minicomputer applications? Minicomputer

18. AVAILABILITY \Z2 Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

FY For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIED

1

' Order From Sup. of Doc, U.S. Government Printing Office Washington. D.C. 20402. SD Cat. No. C13

20. SECURITY CLASS

(THIS PAGE)

22. Price

1

! Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED

USCOMM-DC 29042-P74