SECOND QUARTERLY DATA REPORT FOR RELIABILITY AND MAINTAINASILIT.-ETC U)SEP al M4 S PLOTKA

UNCLFE AA-CFT-81-43 lA NL

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hprt No. DOT/FAA/CT-S1/43 L Y tSECOND QUARTERLY DATA REPORT FOR RELIABILITY

AND MAINTAINABILITY EVALUATION OF THE BASIC WIDEMICROWAVE LANDING SYSTEM AT WALLOPS ISLAND, VIRGINIA

Marvin S. Plotka

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DATA REPORT

: , SEPTEMBER 1981

.J Document is available to the U.S. public through

~the National Technical Information Service,Springfte~d, Virginia 22 161

~Prepared for

U. S. DEPARTMENT OF TRANSPORTATIONFEDERAL AVIATION ADMINISTRATION

TECHNICAL CENTER

Atlantic City Airport. Now Jersey 11114116

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NOTICE

This document is disseminated under the sponsorship ofthe Department of Transportation in the interest ofinformation exchange. The United States Governmentassumes no liability for the contents or use thereof.

The United States Government does not endorse productsor manufacturers. Trade or manufacturer's names appearherein solely because they are considered essential to

the object of this report.

Technical keport Oocuonteion Pago

1. Report No. 2. Government Accession No. 3. Recipient's Cotolo -

FAA-CT-81-43 6

JECONDJ$UARTERLY DATA JEPORT FOR J&ELIABILITY A14 Se.AItNTAINABILITY VALUATION OF THE JASIC .IE pECROWAVE 6. Performing 0rganization Cede

- LANDING SYSTEM ATY.ALLOPS ISLAND, VIRGINIA. ACT-100

/ i Performing Oganization Report Me.7. Author,%) .- ' * .. .,

9. Perfor,,,i,,'A ,ga action Name and Address 10. Work Unit No. (TRAIS)Federal Aviation Administration 075-325-490Technical Center 11. Contract or Grant No.

Atlantic City Airport, New Jersey 0840513 Tyeo R prt ndP idC vrd__. 13. Type Oi Report end Period Covered

)2. Sponsoring Agency Nome and AddressU.S. Department of Transportation D ata Xept ,.......Federal Aviation Administration Augl--- Oc t 8OSystems Research and Development Service -. ponsortng gcy t-oeWashington, D.C. 20590

15. Supplementary Notes

16. Abstract

This is the second quarterly data report on the reliability and maintainabilityevaluation of the Basic Wide Microwave Landing System located at Wallops Island,Virginia. It covers the period August 1 through October 31, 1980. Chargeablefailures are listed, and calculated reliability values are presented. System andsubsystem mean time between failure (MTBF) and mean time to repair (MTTR) measuredvalues are included. System MTBF's are compared with predicted and specifiedvalues.

17. Key Words 18. Distuibtution Statement

Basic Wide MLS Document is available to the U.S. publicMLS through the National Technical InformationPDME Service, Springfield, Virigina 22161

19. Security Clessif. (of this report) 20. Security Clessif. (of this poeg) 21. No. of Pages 22. Price

Unclassified Unclassified 20

Form DOT F 1700.7 (8-72) Reproductiotn of completed page authorized///

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TABLE OF CONTENTS

Page

INTRODUCTION 1

Purpose I

Background 1

DISCUSSION 1

BIBLIOGRAPHY 3

APPENDICES

A - Chargeable Failures List

B - First Quarterly Data Reporting Period Data Tables

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LIST OF TABLES

Table Page

1 MLS and PDME System Unit Types, Failures and Maintenance 4(August 1 to October 31, 1980)

2 MLS Subsystems Enclosures, Failures and Maintenance 5(August 1 to October 31, 1980)

3 MLS Subsystems Failures and Maintenance 6(August 1 to October 31, 1980)

4 MLS and PDME Systems Failures and Maintenance 6(August 1 to October 31, 1980)

5 MLS and PDME Systems Unit Types, Failures and Maintenance 7Summation (May 21 to October 31, 1980)

6 4MLS Subsystems Enclosures, Failures and Maintenance Summation 8(May 21 to October 31, 1980)

7 MLS Subsystems Failures and Maintenance Summation 9(May 21 to October 31, 1980)

8 4MLS and PDME Systems Failures and Maintenance Summation 9(May 21 to October 31, 1980)

9 Basic Wide MLS and PDME Specified, Predicted, and Summated 10Measured MTBF Values

iv

INTRODUCTION

PURPOSE.

The purpose of this project is the evaluation of the Microwave Landing System (MLS)Basic Wide System at Wallops Island, Virginia, to determine the operational sub-system and system Mean Time Between Failures (MTBF) and Mean Time to Repair (MTTR).Failure rates are to be calculated. All the values will be compared with thosepredicted by the contractor. Reliability and maintainability weak points orproblems areas will be determined. This data report documents the evaluation databetween the dates of August 1 and October 31, 1980.

BACKGROUND.

A reliability and maintainability project, No. 075-725-490, entitled "Reliabilityand Maintainability (R&M) of Basic Wide MLS at Wallops Island (NASA)," wasestablished at the Federal Aviation Administration (FAA) Technical Center in May1980 under the Landing System Technical Program Document No. 07-115. Reliability

* Engineering Section (ATC-152) personnel were assigned to support the effort underthe technical administrative direction of the program manager (ACT-100E). Data

* collecting commenced on May 21, 1980, for the MLS and the Precision DistanceMeasuring Equipment (PDME) at the site.

DISCUSSION

In the first quarterly data report (report No. FAA-CT-81-14, dated April 1981), apresentation was made on the project data collection, reduction, and analysis.

The chargeable failure test data for quarterly report period August I toOctober 31, 1980, are shown in tables 1 through 4, progressing from equipment unitsin table 1 through the system level in table 4. The summed chargeable failuretest data for the period May 21 through October 31, 1980, are shown in tables 5through 8. The equipment levels progress from equipment units in table 5 throughthe system level in table 8. In table 9, the MTBF specified, predicted, andsummated measured values for the Basic Wide MLS and PDME are presented.

At the element and enclosure level, all failures which meet the criteria for beingcounted as chargeable are used in the data calculations. The Bendix Corporation'sreliability model definitions are used in computing subsystem and system valuesbecause of equipment designed graceful degradation. Appendix A is a chargeablefailure list including the date, definition, and explanation. Appendix B includesall the tabulated data reported in the first quarterly data reporting period

(May 21 through July 31, 1980).

Within this second reporting period failures occurred which did not meet all thecriteria for being counted as chargeable. All of these failures caused the sub-system or system to not transmit. The azimuth subsystem had 29 nonchargeablefailures, and the elevation subsystem had 59 nonchargeable failures. Twenty-two ofthe elevation subsystem nonchargeable failures were due to the azimuth subsystem's

1-

not transmitting. When the azimuth subsystem is down (not transmitting), itdoes not transmit sychronization or timing signals via the intrasite cable to theelevation subsystem. If the elevation subsystem does not receive the synchroniza-tion and timing signals, it goes into executive fault and does not transmit. Ifthe synchronization and timing signals remain off for more than 5 minutes, theelevation subsystem stops trying to restart automatically and remains down untilmanually restarted. Most of the downtimes of the respective subsystems related tothese nonchargeable failures were attributed to the technician's not being on duty(nights and weekends). The PDME system had no nonchargeable failures.

Included in the nonchargeable failures were four main-base momentary power outages.They were a complete loss of power to the MLS equipment for I to 2 seconds asrecorded on the Rustrak recorder. The effects of the momentary power outages onthe MLS subsystems varied from 0.08 hour to 38.5 hours. Most of the extended timeloss was due to the incidents occurring at night or on the weekend when the site'stechnical person was not on duty. The automatic restart circuits in each subsystemattempted for 5 minutes to reactivate the equipment after the return of power. Ineach of these momentary power outages various signals remained in the executivefault status for a period exceeding 5 minutes. Thus, the MLS subsystems remaineddown and required manual intervention to return them to operation. The totaltime lost by the azimuth subsystem was 45.58 hours. The total time lost by theelevation subsystem was 85.75 hours. The PDME system lost only momentary time,returning to service with the return of power; and, subsequently, it was down onlyfor the actual power loss period.

The intrasite signal cable between the azimuth and elevation subsystems wassevered by construction equipment. The time lost by the elevation subsystem inthis incident was 95.25 hours and is considered nonchargeable. The intrasite cablecarries the synchronization and timing signals from the azimuth subsystem shelterto the elevation subsystem shelter. When these signals are not actively present atthe elevation subsystem, it goes into the executive fault status.

The total MLS azimuth subsystem downtime due to preventive maintenance (PM)is considered nonchargeable and consisted of 4.48 hours during this reportingperiod. The MLS elevation subsystem had 3.77 hours of downtime due to PM andan additional 3.70 hours of downtime due exclusively to the PM on the ILS azimuthsubsystem. When PM is being performed on the elevation subsystem, the azimuthsubsystem is unaffected. When the azimuth subsystem is down for PM, no synchroni-zation or timing signals are transmitted via the intrasite cable to the elevationsubsystem, causing the elevation subsystem to go into the executive fault status.PM done on the azimuth and elevation subsystems is independent of the PDME systemand vice versa. No PM was done on the PDME system.

The air-conditioners and heaters had no chargeable or nonchargeable failures.There is one air-conditioner and heater in each of the azimuth and elevationsubsystems' electronics shelters of which there is one in each subsystem. Theazimuth subsystem's guidance antenna has two air-conditioners and heaters, andthe elevation subsystem's guidance antenna has one air-conditioner and heater.

Remote control panels were installed in the air traffic control (ATC) tower.In a normal ATC installation, these remote control panels would have controlof the MLS equipment when the respective subsystem is not in maintenance. At thisinstallation, the normal duty hours of the tower personnel and the MLS site techni-cal person were the same. In addition, since the MLS is not a production item,

2

some portion of it is usually being worked on by the site technical person.Therefore, the MLS was usually left in the local control status, requiring manualintervention at the site each time a subsystem required restarting. By virtue ofthe MLS technical persons being on the base, an MLS subsystem malfunction could beresponded to within approximately 15 minutes. In addition, by virtue of theremote control panels, the ATC tower personnel would know of the MLS subsystem'scontinued nontransmitting status and could notify the site technical person.

The next report will cover the data collection period of November 1, 1980, throughJanuary 31, 1981.

BIBLIOGRAPHY

Bendix Communications Division, Antenna Subsystem, Basic Wide Ground Equipment,Microwave Landing System, Preliminary Technical Manual, Operation and MaintenanceInstructions, Volume I, Contract DOT-FA78WA-4180, T16830.1, Baltimore, Maryland:Bendix Corp., March 1980.

Bendix Communications Division, Ground Electronics Subsystem, Basic Wide GroundEquipment, Microwave Landing System, Preliminary Technical Manual, Operation andMaintenance Instructions, Volume I, Contract DOT-FA78WA-4180, T16830.3, Baltimore,Maryland: Bendix Corp., March 1980.

Bendix Communications Division, Ground Subsystem, Basic Wide Ground Equipment,Microwave Landing System, Preliminary Technical Manual, Operation and MaintenanceInstructions, Volume 1, Contract DOT-FA78WA-4180, T16830.2, Baltimore Maryland:Bendix Corp., March 1980.

Bendix Communications Division, Microwave Landing System Phase III, (Basic WideConfiguration), Final Report, Volume I, Contract DOT-FA78WA-4180, Report No.MLS-BCD-R-4180-1, Baltimore, Maryland: Bendix Corp., December 1980.

Bendix Communications Division, Microwave Landing System Phase III, (Basic WideConfiguration), Final Report Volume II, Contract DOT-FA78WA-4180, Report No. MLS-BCD-R-4180-1, Baltimore, Maryland: Bendix Corp., December 1980.

Cardion Electronics, Distance Measuring Ground Station Equipment, Model 8974A,Volume I, Instruction Book, Holtzville, New York: Cardion Electronics, 1977.

Cardion Electronics, Distance Measuring Ground StaLion Equipment, Model 8974A,change notice A, Holtzville, New York: Cardion Electronics, September 1979.

Plotka, M. S. and Apostolakis, G. C., Test Plan for the Reliability and Maintain-ability Evaluation of the Basic Wide Microwave Landing System at Wallops Island,Virginia, Report No. FAA-CT-80-187, Atlantic City Airport, New Jersey: FAATechnical Center, July 1980.

Plotka, M. S., First Quarterly Data Report for the Reliability and Maintainabilityfor the Evaluation of the Basic Wide Microwave Landing System at Wallops Island,Virginia, Report No. FAA-CT-81-14, Atlantic City Airport, New Jersey: FAA TechnicalCenter, April 1981.

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TABLE q. BASIC-WIDE MLS AND PDME SPECIFIED, PREDICTED, AND SUMMATED MEASUREDMTBF VALUES

Specified Predicted Summated MeasuredItem MTBF MTBF MTBFNo. Equipment (hours) (hours) (hours)

1 MLS system 1,500 1,632 475.83(azimuth andelevation)

2 MLS azimuth 3,000 3,030 1,145.67subsystem

3 MLS elevation 3,000 3,539 951.67

subsystem

4 PDME system 3,000 2,965* 1,846.79

*The predicted values is for a DME-1 which is commercially available. It does not

take into account the modifications made to the DE-l converting it into a PDME.

10

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APPENDIX ACHARGEABLE FAILURES LIST

(Related to Table 1)

AUGUST 1, TO OCTOBER 31, 1980

Table 4 Failure FailureItem No. Item No. Date Failure Description and Correction

I Azimuth antenna enclosure electronics

1 and 2 10/27 to During an engineering change test earlier this10/28/80 month, transients occurred in the azimuth

subsystem. In repairing the subsystem andbringing it up to operational status, the off-line test was run. Phase shifter positions+48 and +54 were indicated to have failed. Inposition +48 phase shifter serial number (SIN)57 was removed and S/N 172 was installed. Inposition +54, phase shifter SIN 165 was removed,and S/N 45 was installed. There has been nofeedback from Bendix Corp. as to why and whacin the phase shifters went bad. Correctivemaintenance time, 1.0 hour.

3 10/31/80 The nelf-test error was indicated in the beamsteering unit. Used procedure in manual TexasInstruments (T.l.) 6830.1 for searching read-only-memory (ROM) location. Found phase shifterposition +47 was causing the error. Visual inspec-tion showed phase shifter position +48 to have itsfault light emitting diode on. Removed phaseshifter SIN 172 and installed SIN 61. There hasbeen no f eedback from Bendix Corp. as to why andwhat in the phase shifter vent bad. Correctivemaintenance time, 0.5 hour.

2 Azimuth antenna enclosure air-conditioners

none

3 Azimuth antenna monitor antenna

none

4 Azimuth electronics rack

19/9/80 The monitor panel data link fault indicated.Trouble shooting showed the BDA board WA) in theremote control panel located in the air trafficcontrol tower to be defective. Pulled defectiveBDA board and replaced it with a spare. Foundintegrated circuit U12 (55113) to be defective on

A-1

the original board. Ordered a new replacementfor U12. No subsystem downtime since it wasoperating in the local control mode. Correctivemaintenance time for reinstating the remotecontrol panel to operational status was 1.0 hour.

5 Azimuth electronics rack air-conditioner

none

6 Elevation antenna enclosure electronics

none

7 Elevation antenna enclosure air-conditioner

none

8 Elevation antenna monitor antenna

none

9 Elevation electronics rack

1 8/4/80 The amplitude modulator fault indicator showed thisas a maintenance fault. The amplitude modulatormodule in the radio frequency drawer, 1A1AIA2A3,was found defective. It was replaced with a spare.Corrective maintenance time, 1.67 hours.

2 9/25/80 Monitor timing executive fault occurred inter-mittently. Troubleshooting the problem foundintermittent contact between the WCZ boardand its chassis connection. The board number islAIA1A4A14. Adjusted tension of board connectorcontacts and reinserted the respective WCZ board.Reset the local control switches, and the systemwas operational. Corrective maintenance time,

5.33 hours.

10 Elevation electronics rack air-conditioner

none

Li PDME antenna

none

12 PDME electronics rack

1 8/15/80 The replay delay fault was intermittent. Trouble-shooting localized the problem to board 1A2A4.Isolated problem to a cold solder joint on resistorIA2A4R46, which was resoldered. No similar reoc-curence of the problem since then. Corrective

maintenance time, 0.75 hour.

A-2

APPENDIX B

FIRST QUARTERLY DATA REPORTING PERIOD

DATA TABLES

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