( Reaffirmed 2001 )
IS : 9692( Part 7 )  1984
Indian Standard
GUIDE ON MAINTAINABlLITY
PART 7 COLLECTION,
DATA RELATED
OF EQUIPMENT
OF
ANALYSIS
TO MAINTAINABILITY
AND PRESENTATION
Reliability
of Electronic and Electrical Components Sectional Committee, LTDC 3
Chairman
and Equipment
Indian
Members
PROE S. SAWATE Institute of Technology,
Kanpur Representing
ADDITIONAL DIRECTOIL, STANDARDS Railway Board ( Ministry of Railways ) (S&T),RDSO JOINT DIRECTOR, STANDARDS ( S & T )III, RDSO ( Alternate ) All India Radio, New Delhi Snm S. P. BHATIKAR SH~I K. B. MENON ( Alternate ) National Physical Laboratory DR K. C~ANDBA (CSIR ), New Delhi SARI CRAI~ANJIT SIX(IH Hindustan Aeronautics Ltd, Hyderabad Wa CDR K. SURIZSHBABIJ ( Alternate ) Peico Electronics and Electricals Ltd, Bombay DR P. K. DUTTA SURI V. NARAY~NAN ( Alternate ) National Test House, Calcutta SH~I R. P. GROSR Snnr B. C. M~KIXERJEE ( Alternate ) Instrumentation Ltd, Kota SHRI A. P. GUPTA Snn~ I. S. SULAKH ( Alternate ) Overseas Communication Services, Bombay SHRI R. K. JAYADIZV SI~RI HARDEV SINCTE( Alternate ) Ministry of Defence ( DGI ) BRIU L. G. KETRAX LTCOL V. K. KIIANNA ( Alternate) The Radio Electronic & Television Manufac. SHRI S. P. KULKAI~NI turers' Associatton, Bombay SHRI S. M. KHU~SALE ( Alternate ) Electronics Corporation of India Ltd, Hyderabad SRRI K. M. MANICAD Snm B. BHASKAR RAO ( Alternate ) Directorate General of Civil Aviation, New Delhi 15~1 D. C. MEHTA SHRI R. V. &RANK ( Alternate ) ( Continued on page 2 )
0 Cobright
INDIAN STANDARDS
1985 INSTITUTION

t
This publication is protected under the Indian Cofiyright Act ( XIV of 1957 ) ana reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.
IS:9692(Part7)1984 (Continuedfrom
pug6 1 ) RefirssGnling
Mcmbsrs
SHRI H. V. MEHTA Posts and Telegraphs Board, New Delhi SHRI S. KALYALINOAX ( Alternate ) Indian Electrical Manufacturers' Association, SHRI S. R. MEHTA personal capacity ( Department of Elsctrical Engineering, Indian Institute of Technology, Kharag ur ) SHRI K. R. ANANDAXUMARAR NAIR LucasT 4 S Ltd, Madras SHRI C. RANQANATH~N ( Altarnate ) Bha~~mh~omic Research Centre, Trombay, SHRI D. V. PETXCAR SHRI A. K. BABAR ( Altcrnats) SHRI P. S. K. PRASAD SHRI K. RAMGIOPAL SHRI SIHARAN DE ( Altarnata ) SHRI R. SOMASUNDARAM
I
SXRI T. C. GOSALIA DR K. B. MIEHA
(
Alternate )
In
Bharat Electronics Ltd, Bangalore ISRO Satellite Centre.( ISAC ), Bangalore Directorate of Technical Development Production ( AIR ), Ministry of Defence and
SHRI R. N. S~ARMA ( Alternuts ) SHIZI H. C. TEWARI Central Electricity Authority, New Delhi SHRI D. P. SINHA ( Altarnate ) Ministry of Defence ( R & D ) BRIC+.J.VAR~HE~E &RI P. K. SHUKLA ( Alternatc ) . Indian Telephone Industries Ltd, Bangalore SHRI B. VIRESALIN~AM SHRI V. MUTBAIAII ( Alternate ) Department of Electronics, New Delhi PR R. P. WADHWA SHRI E. G, NAQARAJAN ( Altcrnafc ) Director General, IS1 ( ExoJcio Member ) SHRI N. SRINIVA~AN, Director ( Electronics ) ( Secretary )
Study of Statistical Problems of Reliability of Electronic and Electrical Items Subcommittee, LTDC 3 : 1
COnVen6r
DR P. K. DUTTA Membars BRIGIR. C. DHINQRA
Peico Electronics ElecGtr;i;
& Electricals
Ltd, Bombay ( North ),
yh!gional e
Test Laboratory
SHRI S. MITRA ( AltcrnatC ) Ministry of Defence ( DGI ) LTCOL G. R. MALHAN MAJ RAJAN MANNIL ( Alternate 1 Telecommunication Research Centre, New Delhi Snnr N. C. MISIIRA SHI~I T. S. KUPPUSWAMI ( Alternate ) Indian Statistical Institute, Hyderabad SHRIV. NARAYANA Bharat Electronics Ltd, Bangalore SERI P. S. K. PRASAD ISRO Satellite Centre ( ISAC 1. Bantxalore Snn~ K. RAMUOPAL Ministry of Defence ( R`& D ) " " SH~I P. K. SHUKLA NaticDnaa. Phystcal Laboratory ( CSIR ), New DR Y. V. SOMAYAJULU e 1 SHRI V. N. S~AKMA ( Alternate)
2
IS I 9692 ( Part
7 )  1984
Indian Standard
GUIDE ON MAINTAINABILITY
PART 7
OF EQUIPMENT
OF
COLLECTION, ANALYSIS AND PRESENTATION DATA RELATED TO MAINTAINABILITY
0.
FOREWORD
Institution on 16 July 1984, after the draft finalized by the Reliability of Electronic and Electrical Components and Equipment Sectional Committee had been approved by the Electronics and Telecommunication Division Council. 0.2 This guide is intended to make recommendations for the standardization of maintainability practices, and to stimulate ideas in the maintainability field. Organizations acquiring items will find the guide useful in assisting them in defining maintainability requirements and in associated Item suppliers will benefit from use of the guide, gaining programmes. an understanding of the requirements for achieving and verifying maintainability objectives. 0.3 This standard, Part 7 in the series on ` Guide on maintainability of equipment ' is intended to present a suggested approach for the collection, The other ,analysis and presentation of data related to maintainability. parts of this standard are as follows: Part 1 Introduction Part 3 Maintainability Part 5 Maintainability Part 6 Maintainability to maintainability requirements programme studies during the design phase verification in specifications and contracts Part 2 Maintainability
0.1This Indian Standard ( Part 7 ) was adopted by the Indian Standards
Part 4 Test and diagnostic procedures
0.4 In the preparation of this standard, assistance has been derived from the IEC Document 56 ( Secretariat ) 157 Draft' Guide on maintainability of equipment: Part 7 Collection, analysis and presentation of data related to maintainability `, issued by the International Electrotechnical Commission ( IEC ) . 3
IS : 9692 ( Part
0.5
7 )  1984
This standard is one of a series of Indian Standards on reliability of A list of standards electronic and electrical components and equipment. published so far in this series is given on 4th cover page.
1, SCOPE 1.1 This standard ( Part 7 ) gives information presentation of data related to maintainability. 2. TERMS AND DEFINITIONS on collection, analysis and
2.1 For the purpose of this standard, the following definitions shall apply in addition to those specified in IS : 1885 ( Part 39 )1979* and IS : 76901975t. 2.1.1 Maintenance Policy  A description of the interrelationship between levels of maintenance, indenture levels, and lines of maintenance to be applied for the maintenance of an item. 2.1.2 Maintenance to a specific item. 3. INTRODUCTION 3.1 Maintainability related data are required at several points during the It is the objective of this part of item life cycle for evaluation purposes. the guide on maintainability of equipment to provide an overview of the considerations to be taken in the collection, analysis and presentation of maintainability related data, 3.2 Collection, analysis and presentation of maintainability related data may be required during and at the completion of design and during item Such data are typically submitted by the item production and operation. supplier to the intended user in a maintainability data report which presents the data along with the supporting rationale. Key maintainability characteristics of I concern are corrective and preventive maintenance downtime and manhours. Maintenance support information should also be provided defining the personnel and facilities required. 3.3 In the presentation of maintainability related data, it is important to consider the maintenance concept, the definitions of terms, the description of data sources, the analysis procedures, and the method for displaying the data. The suggested scope for each of these factors is outlined in this part of the guide.
*Electrotechnical vocabulary: Part 39 Reliability of electronic and electrical items ( jirst r.wi&w ) . *Mathematical guide to the terms and definitions for reliability of electronic equipment and components ( or parts ) used therein.
Come/d 
Application of a general maintenance
policy
4
IS : 9692 ( Part 7 )  1984 4. MAINTENANCE CONCEPT DEFINITION
4.1 In order to provide a clear understanding of the maintainability related data to be presented, it is essential that the item maintenance concept for which the data is applicable is defined. The type of information that typically is required to describe the applicable maintenance concept is illustrated in Appendix A. 5. DATA SOURCES 5.1 General  Maintainability related several sources such as the following: data may be developed from
a) Historical data from similar items, b) Item design/manufacturing data, and c) Item demonstration and field data. 5.1.1 Points for consideration ate given in 5.2 to 5.4, in describing each of these data sources
5.2 Historical Data  The origin of the historical data ( field operation, repairshop experience ) and the item on which they are based should be described and the rationale for their applicability to the current item presented. Methods used to collect the data along with training and skill level of maintenance personnel observed should be stated. Differences that could be expected to effect the applicability of historical data to the item under consideration should be discussed [ see IS : 9692 ( Part 6 )1983* 1. Historical data should primarliy be used during the concept definition phase for specification purposes. In later phases of the item life cycle, they should be considered in relation to actual data gained on the current item itself. 5.3 Item Design/Manufacturing Data  If maintainability related data are developed from data generated during the design/manufacturing phase ( development tests, manufacturing or assembly lines ) through the use of design analysis or prediction, the method used shall be identified. A discussion should be provided of how the method was selected and applied along with noting any possible limitation in data accuracy. Item qualification and acceptance with regard to maintainability should primarily be based on dcsign/mahufacturing data.
*Guide on maintainability of equipment: Part G Maintainability verification.
5
IS : 9692 ( Part 7 )  1984. 5.4 Item Demonstration and Field Data  Maintainability related data may be developed from demonstration tests conducted using prototype hardware or from data generated during item use ( repair workshop, field operations ). Methods of selecting maintenance actions, data monitoring and recording techniques should be described. Skill level of maintenance personnel and the training they had received should be noted. Several maintainability verification techniques have been stipulated in The feedback of demonstration and field data IS : 9692 ( Part 6 )1983*. is the primary basis for sustaining engineering activities during the inservice phase of the item life cycle. 6. ANALYSlS PROCEDURES
6.1 When presenting maintainability related data for the purpose of testing the compliance with stated maintainability requirements as well as for determination purposes, the analysis procedures used should be described. The points of concern include the following: a) Data editing, analysis, computation. and
b) Distribution c) Parameter
6.1.1 Data Editing  Actions taken to assure the accuracy, completeness and validity of the data should be described. If any censoring is performed, the rules used and reasons for performing these operations should be presented. related data is to be 6.1.2 Distribution Analysis  If the maintainability treated parametrically it is necessary to determine the distribution of the basic data. The method to be used in testing the distribution form should be described along with the rationale for its selection. Common methods for distribution analysis include the Chi square, KolmogorovSmirnov and graphical tests. Appendix B to this standard provides further information on distribution analysis methods. 6.1.3 Parameter Computation  The basis for computing all maintainability parameters to be presented should be stated. If selected parameters are to be computed on a cumulative or interval basis, the method to be If maintainability mathematical models are to used should be detailed. be used, they should be fully described. Appendix B provides guidance on the computation of the arithmetic and geometric means, confidence limits and selected fractiles for the lognormal, normal and multimodal distributions, which are most commonly used in maintainability. For other distribution types, corresponding values can be found in statistical textbooks.
*Guide on maintainability of equipment: Part 6 Maintainability verification
6
IS:9892
7. DATA DISPLAY
(Part 7)1984
7.1 Maintenance
data displays are typically developed for the following:
a) Corrective actions, and b) Preventive actions. In addition, maintenance support data should be presented to provide necessary background information. 7.2 Correcthe Maintenance  Corrective maintenance time is typically expressed in active repair time comprised of several subelements. Appendix C presents a typical summary recording of the details of a series The form of active repair elements included in corrective maintenance. provides for identifying the failed unit ( unit reference ), the type of failure considered ( fault ), the technician(s) performing maintenance ( name ) , the number of men required, and the several elements of downtime. It would be applicable for data derived from development or operational tests. Data derived from historical or prediction sources may be presented on the basis of expected average ( mean ) or median values rather than by individual tasks. Appendix D illustrates tl:,: form that data from these sources could take along with summarized ( averaged ) test data. In this form, for each major sub unit of the item, the average If desired, active repair time is shown along with its standard deviation. selected fractiles could be displayed in lieu of the standard deviation, that is, 95th fractilc. Other parameters sometimes used to characterize certain aspects of corrective maintenance include the following: a) Automatic failure detection ratio ( item operating ), b) Automatic failure recovery ratio, c) Automatic or manual failure localizing with accuracy of 1 to n plug in units, d) Efficiency of automatic or manual repair procedures, and e) Mean or fractile active recovery time. Average values for these parameters may be derived from historical or prediction sources and summarized test data. 7.3 Preventive Maintenance  Presentation of preventive maintenance data requires that the duration of the tasks be identified along with their frequency. Appendix E illustrates the form to present these data. Preventive maintenance times are usually expressed as active preventive maintenance time. Observed nonactive preventive maintenance down time can be added when necessary. To aid maintenance planning estimated maintenance manhours for each task are also desired, In addition to the detailed task information an overall summary of preventive maintenance times should be presented, 7
IS : 9692 ( Part 7 )  1984
support data may be 7.4 Maintenance Support Data  Maintenance required to aid the item user to properly plan for its support. Appendix F illustrates the type of information that may be required. Principal data elements should be supported by information on the recommended maintenance concept, training requirements, special tools, or other support equipment and technical documentation used. Additionally the item maintenance requirements should be detailed in terms of major maintenance tasks to be performed and the requirements for personnel skills and support equipment, along with their impact on downtime and manhours. Further parameters such as the following can sometimes be used to cover certain maintenance support aspects and may be added as required: a) Mean or fractile administrative b) Mean or fractile administrative c) Spare parts usability ratio, d) Mean or fractile delivery time of spare parts repair, and e) Mean or fractile delivery time of software repair. recovery time, repair time,
APPENDIX ( Clause 4.1~~)
A
EXAMPLEOFTHEMAINTENANCEC~NCEPTINF~RMATION
ITEM REFERENCE _ ITEM DESCRIPTION _ 
DATE
M'IAIXTEUANCE CoNcmT a
Lmcs
OF
M XlliTli.NAXCE*
REPLACEMENT LEVEL
SKILL REQUWEMENTS
SUPPORT EQUIPMENT REQIJIXEMENTS
TECHNICAL DOGUHENTATION REQUIREIENTS
TR AININQ REQUIREMENTS
1.
OnItem
(Organizational )
2.
Local ( Intermediate )
3.
Depot
*Lines of maintenance use location.
are illustrative
only.
The
lines used should be consistent with item maintenance
needs and
IS t 9692 ( Part
7 )  1984
APPENDIX
B
( CZau.ses 6.1.2 and 6.1.3 )
MAINTENANCE Bl. LOGNORMAL DATA ANALYSIS METHODS
DISTRIBUTION
Bl.1 A random variable x has a lognormal probability distribution if the logarithm of the variable is distributed normally. The lognormal probability density function is: f(x)= ~~~1;;exp{~(~0g~~B)`j,0 = geometric mean = ee _ e'Us E= ell + &,e, where sp is normal deviate
=
properties
of the log(81 (9) (10) (11) (12)
(13) The lognormal is a positively skewed distribution, with degree of skewness increasing as us increases. From the above formulae, it is seen, that mode < median < mean. Because of the parameters 8 and us, the lognormal is a relatively flexible distribution. B2. NORMAL DISTRIBUTION
Coefficient of variation
I
z'p
_cc
Jk
`d2 &
= ( e@ 1 )
B2.1 The probability density of the normal distribution is given by: f(x)= Parameter U&e 4 p+)' , _ x
For ~1, a fi percent I\ ( CLtp,
confidence
interval
is given by:
n1
&,G,
;
+
tp,
n1
&,/n
)
(19)
with ( n 
where t,, nl is the p fractile degrees of freedom. For u*, a p percent confidence )*@
of the t distribution
 1)
interval
is
(nl ( where (R x2pp1
,
3
(nl)
X&
is
n1 >
(20)
the Xs distribution with
Xs p,, nl is the of freedom X,
pi
fractile
of
1 ) degrees The p fractile
XP =
and pi 
& = p.
is given by:
tpfJ
p +
(21)
where (22)
(23) Values distribution. B3. for xp may be obtained from standard tables for the normal
MULTIMODAL
DISTRIBUTION
B3.1 Due to the nonhomogeneous nature of the design for some items, the observed maintenance time distribution may be found to have two or more modes. Such cases may be identified if the composite data fails to pass a may be accomplished lognormal goodnessoffit test. A further verification by separating the data into logical groups based on its design source and performing standard statistical tests to determine if the sample data groups If the populations are judged to be came from different populations. different and also determined to be individually lo~normal, the procedures If they are determined outlined in subsequent paragraphs may be used. to be from different groups but not lognormal, the appropriate distribution form should bc substituted for the lognormal distribution in the method outlined.
12
IS : 9692 ( Part 7 )  1984
The probability distribution N types of maintenance times is: functio.1 pdf, of a mixed ( X ) where m, . . . . . . .., + distribution of
pdf of maintenance
The
ml
f(x)
=
mlfi
( X
> +
times of type
+ ..,...... i and
mN fN
fi mN
ml +
( X ) is the
= 1.
values may be estimated
by the relationship:
i=
c
(24)
h
1
where Ai = failure rate of type i. type of maintenance exp [ >2a,B actions be denoted ( log0 x 4 )`I by: Let the pdf of the ith
fi
( X)
=
x
uii
ui =
2~_
7r
(25) (26) (27)
with mean
pi =c! Oi+Ui*/2
and variances Then
+a,8 e28 1 ( &Ql)
distribution
mlfl ( x) +
the pdf of the mixed
f( with mean x) P = =
of maintenance
......... + mN PN
. ..+mN(
times X is
( x >
mNfN
(28) (29)
ml PI ,t ...... ... +
and
variance
v =
ml
( aIs +
~1~ ) +
ai,+
p:)


vz (30)
The fi fractile mPl for X,,
X0 is determined ( X, ) +
by solving ( X,
dz
. . . . . . . . . + "kFN
) 
J' distribution function
(31)
of
where Fi ( X ) =
ith type of maintenance
action.
I
X
ofl (cl
is the
Solution of this equation for X, may not be obtained in closed form but a numerical procedure may be uPed. One simplified approach* based
*I. B~JRB; A useful Application to Simulation, Distribution approximation to the Nornal Technoaetrics, 9, 1967, pp 647651. Function with
13
n : 9692 ( Part 7 )  1984 on a closed form approximation below: for the normal distribution is presented
a) Choose a tolerance factor, TOL such that estimates of X, which yield percentile values differ by not more than TOL from the true value of p are acceptable ( for example, TOL = 0.005 ). b) Choose an initial value for X,, c) For each type of maintenance log,
ZI = .
say Xx.
One possibility times.
is the
smallest p fractile of the N types of maintenance time, compute
x;  ei
Ql
(32)
d) Calculate .hf ?= c i =l
ml [ 1 + ( 0.644 669 3 + ~161 984ti )4*`JT4 l8*1@
( 1 
e)
If
I Y 
fi ) 1 <
pth
TOL
then
Xp*
(33)
is the estimated
percentile.
If the absolute difference be increased. lhample: Assume parameters:
exceeds the tolerance
factor,
repeat steps
(c) and (d) with new values of Xp*,
If r < 1  &, the next X*p should
If r < 1  fi,, XP" should be decreased. two types of maintenance, 61 = 3.0 Q1 = 0.5 ml = 0.7 with the following e1 = 1.0 u1 = o2 ml = O3 Applying the above logalognormal
The 90th percentile for the mixture is desired. rithm yields 90th percentile value of 34. B4. DISTRIBUTION ANALYSIS METHODS
B4.1 Tests for the distribution form using the sample data may employ such techniques as Chi square, KolmogorovSmirnov, or graphical procedures employing special graph papers. Of these methods, the KolmogorovSmirnov or dtest is considered superior and will be described in more  detail.
*I. BURR;
Application
A useful approximation to the Normal Distribution to Simulation, `Tahnomctrics 9, 1967, pp 647651.
Function
with
14
IS : 9692 ( Part 7 )  1984 The dtest is accomplished by plotting the hypothesized theoretical distribution ( for example, lognormal ) using, as appropriate, the observed data for parameter estimation ( for example, mean and standard deviation ). About this theoretical distribution, boundaries are constructed which are f. d probability units. Table 1 provides a limited set of thed values which are selected, based on data sample size and the Jevel of significance (a ) for which the test is to be conducted. The observed data distribution If the observed function passes outside the boundaries at is next plotted. any point, then the hypothesized theoretical distribution is not consistent Conversely, if the observed function always remains inside with the data, the boundaries, the hypothesis concerning the underlying distribution can not be rejected. To illustrate the use of the technique, ane xample is p:ovided. Table, 2 presents a set of observed data which will be tested for the lognormal distribution. The natural log of each observed time was taken and the mean 9 and the variance us of the log values computed. Using these values, a theoretical lognormal distribution was plotted in Fig. 1. Selecting a 5 percent significance level, with the sample size of ten, the tabled critical d value was found to be 0.41 ( see .Table I ). Since the estimates of e and us are used in generating the theoretical distribution, this value is corrected by multiplying it by O67 yielding a result of d = 0.295. The observed maintainability the nonparametric equation: function was calculated by the use of
$(X,)=k n+
where x,
1
(34)
= observed time of the ktb ordered maintenance = estimated probability that a maintenance pleted within Xk time units, and number of observed maintenance actions.
action,
"F ( X& )
action is com
n=
Figure 1 shows the observed and theoretical distribution along with the KolmogorovSmirnov boundaries. It is seen that the observed distribution falls within the boundaries indicating that the data could have arisen from a lognormal population with a parameter B = 3.19, (r = 0,358. 15
IS : 9692 ( Part 7 )  1984
TABLE SL No.
1 CRITICAL
SAMPLE SIZH (2) 5 10 15 20 30 40 50
VALUES
OF d, KOLMOGOROVSMIRNOV ( ClauseB4.1 ) LEVEL OF SIGNIFICANCE ( a ____ __ h0.10 0'05 (4) (5) 0'510 0'565 0'368 0'410 0'304 0.338 O264 0'294 0.22 0'24 0.19 o21 0'17 0'19 1.22 c 1'36 =z d/n )
TEST
(1) i) ii) iii) iv) v) vi) vii) viii) Over
rl.0'15 (3) 0,474 O342 0283 0,246 0.20 O18 0'16 1.14 77
____ 0'01 (6) 0'669 0'490 0'404 O356 0.29 0'25 0.23
~
1.63 _ d/n of the NOTE  The d values shown are based on a complete specification hypothesized distribution. If sample data is used to estimate the parameter(s), multiply the tabled dvalue by 0'80 for testing the exponential and by 0.67 for testing the normal distribution. 50
THEORETICAL 1
TIME Fro. 1 EXAMPLE
(MINUTES) ANALYSIS
DISTRIBUTION
16
IS t 9692 ( Part 7 )  1984
TABLE 2 SAMPLE MAINTENANCE DATA SET
( Clause B4.1 )
RANK, k
OBSERVED TIME&
IN(Xk)
F(Xk)
CUYULATIVE PBOBABILITY
(1) i)
ii) iii) iv) v) vi) vii) viii) ix) x)
(2)
10 15 17 18 20 22 27 35 50 75
(3) 2'30 2.70 2.83 2.89 3.00 3.09 3.30 3'56 3.91 4'32
(4) 0'091 0.182 O273 0.364 O454 0.548 0'636 0'767 O818 0'909
Mean ( X ) = 28'9 minutes. Mean = ( 0 )  3'19 f time being given in minutes. Variance ( us ) = 0'358 t
17
APPENDIX ( Clause 7.2 )
ACTIVE
TASK NGJIBER UNIT REFERENCE FAULT
C
REPAIR
NAME
TASK DATA
StiMMiRY
FORM
NCMBER ACTWE REPAIR TIB~ESUB ELEMENTS( HOURS ) oF MEN r___h_________, Diagnosis TechniRestoCheck ManTotal cal ration hours Delay 1 2 0.2 o7 0.1 0.2 0'1 0.2 0'1 0.2 0.5 1.3 0.5 2'6 
1 2 3
LRA* 1 LRA*I LRA+5
CRI C24 
APPENDIX ( Clause 7.2 )
ACTIVE
UNIT DI~QNOSIS TIME REFERENCE r*, Avg. Std. Dev.
D
REPAIR
TIME
SUMMARY
FORM
FINAL CHECK TIME TOTAL TIXE cYh_? T._*~ Std. Dev. Avg. Avg. Std. Dev. 0'1 0'2 0.05 0'05 0.5 1.3 0'05 0.09
TECHNICALDELAY C*7 Std. Dev. Avg. 0'1 0.2 0'05 0'05
RESTORATION TIME C_h___~ Avg. Std. Dev. 0.1 0'2 ..0.05 0.05
LRA*1 LRA*5
O2 0.7
o05 0.1
+LRA 
Line replaceable assembly.
APPENDIX ( CZazLse 7.4 )
EXAMPLE
ITEXREFERENCE
F
OF MAINTENANCE
SUPPORT
DATE
DATA
ITEM DESCRIPTION
ITEX FUNCTION
MAIXTEX_~NCE
CONCEFT
TRAINSQ
CONDITIONS
SPECIAL TOOLS, TEST oa SUPPOXT EQUIP~~ENT UsED
TECESICAL DOCGB~ENTATIONUSED
ITEM
MAINTENANCE
CONDITIONS TYPE ACTION PERSONNEL SUPPORT SKILL EQUIPMENT TASK FREQUENCY MANHOURS PERTASK TOTAL MANKouR~
LINE OF REFERENCE DESCRIPTION MAINTENANCE I~T~BER