an improved management approach to upgrade avionic system reliability

KLIVANS: AN IMPROVED MANAGEMENT APPROACH TO UPGRADE AVIONIC SYSTEMS RELIABILITY 23

An Improved Management Approachto Upgrade Avionic System Reliability

Larry S. Klivans were defined and subsequently authorized under the AWG-9production contracts for FY'72-FY'74. The primary goals

Key Words-Management, Operational reliability, Control plan, of this program were extremely ambitious in calling for anMeasurement, AN/AWG-9, Navy F-14 Tomcat, RAISE. increase of over 80 percent in the mean time between mission-

Reader Aids- essential failures without disrupting production deliveryPurpose: Case history schedules established prior to initiating this improvementSpecial math needed: None program.Results useful to: Reliability engineers and managers

DESCRIPTION OF RAISEAbstract-This paper presents an improved reliability-program man-

agement-approach for upgrading avionic system reliability. Manage-ment of the program was by means of an improvement control plan Objectves/Approachthat included continuously updated field performance data, the im-provements planned, and projections of the numerical reliability in- RAISE focused on reducing failures and operating anomaliescrease with the changes incorporated. The use of special teams regardless of frequency of occurrence, rather than on classicalworking concurrently to improve design, parts, and manufacturing reliability failure rate criteria. The approach included determi-processes is discussed. Presented are measured field results that verify ning the causes of malfunctions during manufacturing andthe effectiveness of these improvement efforts.

field use, and developing ways to eliminate those causes byconcurrently improving design change, part specification, and/or manufacturing quality or process control.

INTRODUCTION Figure 2 shows the RAISE program. Corrective action wasdefined and documented, and design and/or part improvements

The Hughes Aircraft Company, Phoenix Weapon System were verified by means of a test-analyze-fix program. AllEngineering Laboratory has devised and implemented a relia- corrective and/or improvement actions were then directlybility program management approach which has improved incorporated into inline production systems, and into prev-the AN/AWG-9 weapon control-system operational reliability iously delivered systems by field retrofit.and availability. This paper describes the key elements of The RAISE program had six dedicated teams to avoid dis-this approach and its results. rupting ongoing production and to focus efforts on achieving

The AN/AWG-9 system provides the weapon control func- increased system reliability.tion for the U.S. Navy F-14 Tomcat weapon system. Themajor functional subsystems in the AWG-9 are radar, control 2) Parts review 5) Analysisand display, computer, missile auxiliary, infrared, and mission 2) Parts review -) Aysisrecorder; the latter two items are optional. Figure 1 showthe AWG-9 installation in the F-14. The first four teams reviewed factory and field failures

The AWG-9 system began full scale production deliveries and/or anomalous performance experienced on developmental,in 1971 and initial production prototype deliveries in 1970. preproduction, and early production AWG-9 systems for theAs of 1976 May, over 250 systems have been delivered to the 1971 and 1972 calendar period and recommended improve-U.S. Navy. The system is deployed at U.S. Navy bases such ments. The analysis team provided reliability/maintainabilityas Miramar, Oceana, and Naval Missile Center, and on several (R&M) data (both raw and reduced) to help other team mem-aircraft carriers. System deployment has also been initiated bers monitor, understand, and measure R&M performance.for the Imperial Iranian Air Force at the initial operating The system test-analyze-fix team operated two systems on abase in Iran. 2-shift basis using simulated F-14 environments in order to

In 1972 July, during the first year of system production, observe and evaluate system, unit, and part failure modes anda change to the system specification incorporated a firm subsequently to evaluate and verify needed reliability improve-mean time-between-failures reliability requirement and a ments prior to design release for incorporation into inlineNavy fleet demonstration program to verify performance. To production or field retrofit. Figure 3 summarizes the RAISEavoid jeopardizing delivery schedules by this increase in rev program plan as related to key milestornes.quired system performance, a new (and possibly unique)program management approach was implemented. The pro- Special Team Actionsgram was given the acronym RAISE, standing for ReliabilityAvailability Improvement System Effort. The program efforts The special team approach permitted rapid development of

24 IEEE TRANSACTIONS ON RELIABILITY, APRIL 1977

UP

CONTROt-~~~S AND00" SDISPLY

MI.SSILEF AUXtl.lARIES POWYf F SUPPLiI>~TRES000Fig. 1. AWG-9 Weapon Control System.

design, specification, test, and process changes. Examples of lous performance of operating units within the computer andteam actions follow. controls and displays subsystems. The results were applied to

Design Review Team-Initial design-problem reviews were hardware and tactical software redesign to improve the reli-held for every unit in each of the weapon subsystems to de- ability of both of these subsystems and their associatedfine problem areas and needed changes. Intensive design- operator interface.change reviews were conducted where recommended and Analysis Team-Three forms of analysis were conducted.alternate design corrective-actions were assessed and approved. 1) All failure data were analyzed to understand failure modes

Parts Review Team-Part failure and replacement data and mechanisms and to assist in defining design changes andfrom the field and factory were evaluated. More than 16 extra testing where needed. 2) All flight test data weremonths of failure reports were reviewed to derive part-applica- documented, classified, and quantified. These data were usedtion changes and part-reliability upgraded specifications. As to provide individual unit trend charts displaying monthly re-a result of this activity, over 50 complex part types (mostly liability. 3) Each of the design changes was evaluated andwith multiple applications) were either upgraded or modified related to the known failure modes so that reliability-improve-to appropriately reduce failure rates. In addition, all inte- ment projections could be made for the system operationsgrated circuit, transistor, and diode specifications were up- subsequent to the improvement incorporation time-frame.graded to provide the higher reliability JANTXV or equiva- System Test-Analyze-Fix Team-The principal objectiveslent parts. were to evaluate the current reliability during simulated mis-

Manufacturing Review Team-Failure report data from all sion environmental conditions and to verify the adequacy ofpreviously fabricated and tested AWG-9 systems were eval- corrective changes. 621 simulated tactical missions were run,uated so that all manufacturing-related or induced failures representing 1741 hours of flight time and 1546 hours ofcould be identified. The current in-process failure and in- ground time. The MTBF of the test hardware was improvedspection records were assessed to determine quality or pro- to 23 hours from 12 hours.cedural related causes. Field failures were categorized asbeing caused by design, part, or manufacturing. For each Control Planproblem area, a combination of inspection, test, and processchanges was made to resolve specific failure causes. In addi- An important element of the RAISE program was thetion, bum-in and card-conditioning were either increased or reliability improvement control plan (RICP) that wasadded to all hybrids and circuit cards, to ensure more relia- developed for each unit in the system to provide the programble hardware in the unit fabrication and assembly phases. manager, the special team managers, the subsystem design

Anomaly Reduction Team-A special software diagnoistic managers, and the Naval Air Systems Command (NASC) andprogram (TRACE) was developed to investigate the anoma- Naval Air Development Command (NADC) personnel with a


FAILURE DATA 1972 1 1973 1 1974 1 1975

F-14 INSTALLATION |SYSTEM DELIVERIES FW71 (DWRI FY-72 (DXP) NFY-73 ENA) FY-74 IEWJ I

CALVERTON VLFULMFVENT

PROGRAM || MT.BFSYSTEM TEST HROPLNFLE DMTBEL SEGUN DO SYSTEM PLANNING ETDM

RELIABILITY DEMO AND COORDS

NS\\\\\\\\\\\< I|FHOGRAVYEVIE S I ODESIGN STATUS STATUS STATUS STATUS FINALPROGRAM REVIEWS 0

RELIABILITY TEST FY 72 FY'7CULVER CITY DEMO VERIF DEMO VERIF

RELIABILITYINTADTALSSYSTEM TEST ACTIVATION AQINITIA DAT LASOT

....... ~~~ANALYZE FIXACUSTN \/RP T

FACTOY DELIVERY LAST

PRELIM MINOR ENGR STARTED MAJOR UNITT MPROVEMENT

S......... x\\\\ SITS J\\\\ ........DESTiCN REVIEWS CHG RELS' REDESIGNED SYSTEMS j INLINE INCORPSITS ~~~~~~~~~~~~~~RELIABILITYPTMUGU ~~~~~~~~~~~IMPROVEMENTil~~~~~~~~~~~PMJUGU D ESIGNANDVERIFY |O C OV

ANOMALY SUBSYSTEM SYSTEM INVEST/FLIGHT TEST ~~~~~~~~~~~REDUCTIONUNTFIV/VERIF/MONITORING

PT MUGUCOMPLETE INITIAL

UNIT REVIEWS

ROVINGFAILURE REVIEW ~~~~~~~~~~~RELIABILITY WRA/SRA::ROVING FAILURE REVIEW m |REVIEW TEAM IMPROVEMENT REVIEW

COMPLETE PRO-

~~~~~~~~~~~~~~~~~~~~~~~~~~CUR EMENTSPEC:

CORRECTION ...UEMNSEC|||.I hIIH-REL PART

EVALUATION I

X ~~~~~~~~~~~~~~~~~~~~~~~RELIABILITY F 1MONITORING

ESI G PARTS/MPG TEAM CORRECTION ACTION

RELIABILITY PATUI/SBYTM/YTMFAILUREANALYSIS TEAM RATE TRACKING/ACTUAL VS PREDICTED

RELIABILITY |CONTROL PLAN Fig. 3. AWG-9 Reliability Improvement Program (FY'72-FY'74)

Summary Program Plan.INCORPORATION

operational failure data; these data were extrapolated to re-11WIflect the anticipated reliability once projected improvements

............. ........could be incorporated.VERIFICATION | The control plan evolved in two distinct steps. 1) Initial

definition of the necessary changes indicated by detailed analy-* 1 RELIABILITY u | | sis and review of all trouble and failure reports from the pre-

......SYSTEM = |MANUFACTURING vious 16 months' testing and use, followed by in-depth reli-':. '.f l l | g:......................::.-.::11abilitydesignreview for the problem areas within each unit.

2) Formulation of the detailed unit control plans, and manage-ment agreement to control the program by means of theseplans. A typical unit control plan (Figure 4) consists of four

Fig. 2. Raise Program Dynamic Process. major sections: A-Corrective change, B-Measurement, C-Pro-jected failure index, D-Unit failure index summary.

The corrective changes (Section A) were generated throughcommon mechanism for defining, controlling, and evaluating a series of design reviews which were oriented toward elimi-benefits of improvement efforts. The RICP presented a mov- nating specific failure modes/causes identified from field data.ing window measurement of current performance, the equip- As a supplement to these reviews, the most recent 8 monthsment improvements planned for incorporation, and the antici- of field experience were analyzed and the predicted failurepated measurement projections after incorporating these im- rates were updated. The changes were identified in categoriesprovements into the hardware. T^he data-time window used paralleling the special team functions to further focus thefor the RICP was limited in order to control closely the change effort. The prime purpose of Section B was to measure


vibration and it experiences two severe impact shocks on|DATE REVISED SU EDGRELIABILITYAPPRORVALS DATE | every flight from the aircraft carrier (one at catapult launch

B NOV 1972 IMPROVEMENTI14 NOV 1972 CONTROL PLAN l and another at landing arrest); it operates in several substan-1/2/73

a tially different modes with the same functional hardwareSECTION: A B C

CORRECTIVE INCORAO- MEASUREMENT MEASUREMENT elements, e.g. as a conventional pulse radar, a high power pulseCHANGE RATION (PY) LAST 2000 HRS1HAC FLT PROUJECTIO Doppler radar, and a unique continuous multiple-target track-FROM PLAN ADNATMUU FAILURE INDEXer adcnius

RELIABILITY RETRO INFY1Y7F73rd.REVIEWS FIT LINE FAILED ITEMS FKH FY'711 FY 72 FY 73 while-scan radar.

DESIGN DESIGN If AWG-9 mission-essential reliability, with a stress factorDUNN DIODE MID PARAMP PUMPfoofoeaigscmprd ttPARAMP PUMP '71 '73 SOURCE 1.0 0.2 0.2 0.2 for severity of operating environment, is compared to thatMULTIPACTOR MULTIPLIERIMPROVEMENT DIODES of a color TV, which ty ically contains only 500 electricalAND ARC M PDADJUSTED parts, operates in only one mode in a sheltered and con-PROTECTION '73

SEL-LMITR 71 73 DIODE SWITCH 0.5 0.5 0.5 0 'ad lmtd rciig nSELF-LIMITER 71 | 73|ILO|PARAM 2.0 0.5 0.5 0.5 trolled environment, an is limited to ceiving, ecoding, andPARTS73

LOW sgas siae qlHI-REL GAIN-REPLACED displaying television transmission sigmils, the estimated equi-WORKMANSHIP PARTS valent TV MTBF would have to be over nine years to beIMPROVED NONE T vin ae oe erQUALITY comparable to AWG-9 reliability.IMPROVED WORKMANSHIPWIRING NONEPROCESS - LEAKAGE,UNIT IMPROPER SHIELD 0.5 0.3 0.1 0.1IMPROVED ATTACHMENT R&M Design ChangesPROCESS - PARAMP.IARMPROE LOW GAI'N 1.5 1.0 0.5 0.3BONDVNG INTERMiTTENT During the RAISE program, over 90 design changes were

PROCESS PARAMP identified and authorized for incorporation into the FY 72-RESIDUAL RESIDUAL FY'74 AWG-9 systems. The following examples illustrate the

NOCHANGE ~~~~INTERM ITTENTAVAILABLE CAPACITORNING 0 L | type and extent of the reliability improvements.

Gunn Diode Oscillator-In the radar receiver, a complex__________________LSECTION 3 1 series of power amplifiers and frequency multipliers was used1TOTAL$ B.0 0.3 2.3 1.6UNIT NO[ 022 UNIT to provide a stable microwave frequency output; these devices

I ~~~~~~~~~~FAILUREBUDGET 3.5 3.0 2.5NAME RECEIVER-RADAR INDEX MARGIN - - - had a high failure rate. The circuitry was redesigned to in-corporate a Gunn diode oscillator operating at the final fre-

Fig. 4. RICP Completed Unit Plan for Radar Receiver. quency and, as a result, the part count was reduced from 115electrical components to only 14. A large gain in reliability(and reduced maintenance actions) was achieved.

the current failure level of those items for which changes Self-Limiting Diode Switch-One of the major failure modeswere planned so as to assess the anticipated improvement. in the radar receiver was complete burn-out or severe degrada-Section C provided the revised failure rate as a function of tion of a parametric amplifier and diode switch due to un-the incorporation schedule and the projected improvement wanted RF input from the transmitter during improperimpact on the failure rate of the change items. The unit blanking. The existing diode switch was replaced with a com-failure index (Section D) indicated the level of improvement pletely interchangeable, self-limiting diode switch whichdetermined from the total projected failure rate and the switches control signals and passively limits RF power.allocated failure rate for that unit. Unit failure rate budgets BeamScraper Gridded Traveling-Wave Tube (GTWT)-Radarwere based on an allocation of the allowable AWG-9 system transmitter reliability was appreciably improved by use of afailure rate. In the case of FY'71 production systems, the new GTWT designed to eliminate tube melts due to stray orminimum mean time between mission-essential failures defocused beam electrons. Essentially, a 'beam scraper' con-(MTBMEF) was 18 hours. For FY'72 and subsequent pro- sisting of a solid copper barrel was inserted between theduction systems, the minimum MTBMEF was increased to cathode and slow-wave structure to absorb the increased heat22 hours. resulting from stray and/or misfocused beam electrons and

The numerical control plan was a key element of the pro- transients caused by radar mnodulator failures. This scrapinggram because it provided a management gauge for assessing action has reduced the maximum temperature in the slow-wavepriorities and progress. Close management control was man- structure by as much as 800°F (4400C).datory since 22 hours MTBMEF is an ambitious reliability Antenna Coolant Lines-Antenna reliability was improvedobjective for a system which is as large and complex as the by modifying the coolant-line assembly. To achieve this, theAWG-9 weapon control system and which is subject to en- number of fittings was reduced by replacing 12 individualvironmental and handling extremes. For example, the tube assemblies with 4 integral assemblies, and the materialAWG-9 contains more than 46000 functional electrical parts was changed from aluminum to stainless steel to eliminate(excluding fasteners, brackets, enclosures, racks, etc.); it damaged or broken tube assemblies.operates in an extremely hostile environment varying from Radar Master Oscillator (RMO) Assembly-Reference os--60°F to +160°F (-50°C to +70°C) in temperature and dillator assemblies in the RMO were redesigned to eliminatefrom sea level to over 70000 feet (20 km) in altitude; it is or reduce spurious frequency oscillations that were vibration-subject to frequent high-Mach flight-buffeting and gun-fire induced and to improve FM sideband noise characteristics.


The redesigned assemblies provided thermal stabilization, and Reliability Demonstration Testa 60 percent reduction in the number of maintenance adjust-ments. The first measure of the success of the RAISE program

All of these changes were conceived and implemented by was provided by a U.S. Navy fleet demonstration test in theusing a preferred part concept which enabled incorporation spring and summer of 1974 by Navy personnel from VF-124of a directly interchangeable forward and backward retrofit (the F-14 training squadron) at the Miramar Naval Air Station.and/or inline system. This preferred part approach simplified Six F-14 aircraft and teni AWG-9 systems were used. Thesethe retrofit of hardware already produced and delivered to AWG-9 systems were produced originally at the Hughes Air-the field. craft Company's El Segundo manufacturing facility under

The time-phasing for inline incorporation of these changes the FY'71 contract. Because most of these systems had beendepended on development and verification lead times, ECP delivered at the time the RAISE program was authorized in(Engineering Change Proposal) preparation, Navy ECP appro- July 1972, all demonstration systems were retrofitted withval lead times, and system reliability requirement projections. negotiated reliability improvement modification kits prior toAssociated ground support equipment (GSE), logistics and the start of the demonstration. The balance of the FY'71support, and data efforts were authorized and initiated as and FY'72 systems was appropriately retrofitted. A 50 hourpart of RAISE to enable these areas to perform the engineer- per aircraft system shakedown period was needed to elimi-ing development and documentation needed to maintain nate all retrofit-induced defects and retrofit-caused aircraft/compatibility with AWG-9 reliability improvement modifica- crew interface problems.tions. Manufacturing implementation and the associated The test plan had a simple pass/fail criterion of ten orproduction effort needed to provide inline unit/system and less AWG-9 system mission-essential inflight failures duringretrofit kit deliveries for FY'72--FY'74 systems were autho- the 180 hour demonstration period. Four mission-essentialrized and performed. flight failures and four additional nonmission-essential failures

were logged during the 180 hour test period.VERIFICATION OF PROGRAM EFFECTIVENESS F MFour Mission-essential Failures:

Measurement Indices 1. Transmitter modulator (circuitry)2. Transmitter GTWT (open filament)

The AWG-9 specification reliability parameter is expressed 3. Receiver switch limiter (shorted)in terms of mission probability of success (Ps) at the system 4. Doppler filter circuit card (threshold adjustment)level. The specification requires that reliability be demon- Four Non Mission-essential Failures:strated by measuring the mean time between mission-essentialfailures (MTBMEF) in a fleet operating environment. The 1. Computer address panel light bulbMTBMEF is based on those failures that would abort or 2. LPRF processor circuit failure not related to flightappreciably degrade AWG-9 system performance in any of squawkits missions. MTBMEF and Ps are related through a system 3. Hand control half-action switch (high force)reliability math model. 4. Signal data converter circuit card (gain adjustment)

The Navy R&M data available from carrier deployment are The following table summarizes the demonstration MTBFnot detailed enough to calculate MTBMEF. Therefore, to en- data:sure that the MTBMEF could be derived, a control datasource was established at the Miramar NAS for operationalsystem usage. Navy maintenance actions forms (MAFs) arecollected daily at Miramar for both organizational and inter- AWG-9 Reliability Demonstration, Miramarmediate maintenance. These MAF data are entered into the March through September, 1974Hughes R&M computer terminal and the central R&M data Totalbank. Key R&M parameters are computed by means of Total Missioncomputer programs. These parameters are: Flight Verified MTBVF Essential MTBMEF

MTBMA (mean time between maintenance actions)Test Phase Hours Failures (hours) Failures (hours)

MTBR (mean time between removals) Shakedown 331 23 15.0 15 22MTBVF (mean time between verified failures) (pre-demo)MTBMEF (mean time between mission-essential failures) Deosrtn 18 8 2.5 44

R&M performance can be obtained via the computer pro-grams in terms of system, unit, assembly, and part perfor- Based on the demonstration phase data, the measuredmance. Data can be further examined in terms of block con- MTBMEF was 45 hours. T'he s-confidence level is 99 pecnfigurations to determine if incorporated improvements in- that the true MTBMEF is greater than the required 18 hours.crease the R&M.


Fleet Deployment Results block configurations. The following data show that the opera-tional reliability of the AWG-9 has continued to increase as

The first two operational F-14 squadrons were deployed on the design, process, and part changes have been incorporatedthe U.S.S. Enterprise following the successful completion of through either inline or retrofit actions. Block III is priorthe AWG-9 fleet reliability demonstration. The operational to incorporating the RAISE R&M improvements. Block IIIAavailability was over 90 percent for the 8-month deployment used the initial portion of R&M improvements defined by theperiod. RAISE program. Block IVA includes all of the RAISE prograni

Key reliability and maintainability indices were determined R&M improvements.for the AWG-9 systems installed in the Enterprise F 14 aircraftfor predeployment operations at Miramar NAS, deployment Block III Block IIIA Block IVAat sea, and postdeployment at Miramar. Shown below are (6000 Fliglht (2500 Flight (10560 Flightthese data along with a comparative measurement for other Hours) Hours) Hours)Miramar-stationed F-14 aircraft during the period the Enter- Parameters JAN - APR 1975 MAR 1975 -

prise was deployed.MTBMA 2.5 4.2 6.4

Enterprise Aircraft MTBR 3.2 4.9 7.0MTBVF 3.5 6.0 8.5

Miramar A/C Predeployed Deployed Post Deployed(2470 Flight (2348 Flight (2856 Flight (1015 Flight

Parameters Hours) Hours) Hours) Hours) CONCLUSION

MTBMA 3.2 3.2 1.4 2.1MTBR 4.9 5.9 2.4 3.6 The RAISE program approach is a viable and proven tech-MTBVF 7.1 8.5 3.2 5.1 nique that can appreciably improve weapon system operationalMTBMEF 27 25 16 21 reliability and availability even when initiated after system pro-

duction begins. It provides a structured approach suitable toimprovement of reliability and maintainability performance

The MTBMEF measures compare favorably with the demoon- in other major military and space avionics systems. Thestration value except for the deployment number. The lower fundamental RAISE program concepts include 1) concurrent,deployment reliability was due to repeated violation of official rapid, and all-inclusive action in the areas of design, parts,Navy operation procedures that resulted in frequent short manufacturing control, and testing, 2) quantification of specificperiods of operation without cooling and extended operation failure items/modes, 3) definition, authlorization, and controlwith marginal cooling. Subsequent postdeployment evaluation of required improvements, 4) verification tlhrough test-analyze-has shown that the excessive operating temperature for the fix, and 5) fleet demonstration of required system perfor-deployed AWG-9 systems has caused the reliability of those mance.particular systems to continue to be degraded due to theshortened life of the overstressed components. Larry S. Klivans; Huglhes Aircraft Company; 8433 Fallbrook Avenue;

A more recent data sample is available from the F-14 de- Building 265, Mail Station P-16; Canoga Park, CA 91304 USA

ployment aboard the U.S.S. Kennedy. The reliability for this LARRY S. KLIVANScruise was excellent and it demonstrates the continuing impact Academicresulting from the reliability improvement program as all sys- BSEE, UCLA - 1950tems are upgraded and proper operating procedures (for cool- MSEE, UCLA - 1952 (Automatic Control Systems)ing) are followed. The measured reliability indices from the MBA, Pepperdine University - 1971U.S.S. Kennedy F-14 operations for the Block IllA AWG-9 Executive Policy Institute - USC, 1976systems are shown below: 26 years in Aerospace Industry

2 years at North American Rockwell: Design Engineer F-86 FlightControl System

Predeployed Deployed 7 years at Northrop Corporation: Responsible for SNARK MISSILEOperations Operations Automatic Flight Control System Development(3971 Flight (4400 Flight 10 years Lockheed Aircraft Corporation: * Responsible for System

Parameters Hours) Hours) Engineering of Agena Satellite Automatic Checkout and LaunchIL KITI"lk---9- A .11 1 AControl Equipment at Factory and at Vandenberg and Cape Ken-MIBMA 3.2 4.9 nedy * Chief Engineer for Chleyenne Helicopter Avionics, Arma-

MTBR 5.0 6.6 ment and Fire Control Systems

MTBMEF 25 0* 32 0* ~~~~~~~~7years Hughes Aircraft Company: Programl Manager - EngineeringMTBMEF 25.0* 32.* & Test Programs - F-14, Phoenix Weapon System*Estimate base upon Miramar detailed Navy maintenance data Other

Over 25 papers on Electronic Circuit Development, Computer-General Operational Results Controlled Support Equipment, Avionics and Fire Control Systems

The effectiveness of the RAISE program is verified by com- Manuscript received 1975 November 13; revised 1976 August 28, 1976paring the reliability indices for the different system production October 16 non

an improved management approach to upgrade avionic system reliability

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