International Journal of Engineering & Technology IJET-IJENS Vol:13 No:02 104

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1 Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No:0 10 Applaon of a Mehodology for Measurng Aerospae Pars by Ulrason Consderng he Measuremen Unerany hrough Analyal and Mone Carlo Smulaon Mehod SILVA, B.C.A, CEFET/RJ Brazl, MOTTA, M.S. CEFET/RJ Brazl, and OLIVEIRA, J.E.F., IFPE Brazl Absra The purpose of hs work s o presen a mehodology o ensure he merologal onfdene durng measuremen of aerospae pars by ulrason, fousng he hkness measuremen of an arplane wng skn. Ths mehodology nvolves from he rera used o perform he seleon of a proper measuremen sysem (ulrason) o he esablshmen of a onformy zones, usng he Mone Carlo smulaon for he unerany measuremen deermnaon. I wll be shown, hrough expermenal analyss, ha mnor varaons n he seps of he proposed mehodology ould refle n relevan qualy loss of he measuremen resul and, n addon, by no o onsderng a reals onformy zone, he aerospae ndusry wll be subjeed o wo possble msakes: he approval of wng skn hkness ou of he allowable lms, ompromsng, herefore, he passengers, rew and arplane safey; or he rejeon (repar requesed) of a wng skn hkness whn spefaon lms, msakenly affeng n he manenane oss. Based on he above menoned onex, he mehodology proposed n hs work objes o preven ha boh suaons may our n he nspeon prae, n reals oss. Index Term Ulrason measuremen, measuremen unerany, Mone Carlo smulaon, aerospae ndusry. I. INTRODUCTION ULTRASONIC nspeon of arplane ndusry plays an mporan role from boh a safey and eonom aspe, sne only mnor arplane open-up aessbly s usually requred, provdng nspeons wh he arplane on he lne (FAA, 1975). owever, n he aerospae ndusry, several arrafs sop s serve o arry ou dealed nspeons of her sruural members and sysems, nludng he power plan. The sop o manenane of he arraf s responsble for ensurng he orre operaon of all omponens and o provde seury. Among several manenane serves o be performed n he arraf durng a hek, he orroson preven SILVA, B.C.A was wh Cenro Federal de Eduação Tenológa Celso Sukow da Fonsea (CEFET/RJ), Avenda Maraanã, 9 Ro de Janero/RJ , Brazl (e-mal: bruno.bas@gmal.om). MOTTA, M.S., Jr., s wh Cenro Federal de Eduação Tenológa Celso Sukow da Fonsea (CEFET/RJ), Avenda Maraanã, 9 Ro de Janero/RJ , Brazl (e-mal: mmoa6@gmal.om). OLIVEIRA, J.E.F s wh IFPE, Avenda Professor Luz Frere, 500 Cdade Unversára Refe/PE , Brazl (e-mal: jefoefepe@yahoo.om.br). and onrol s he one of he mos mporan sne nludes mehods of nspeon and asks o preven orros on n all arraf areas, suh as fuselage, wngs e. The Corroson s a major enemy of arraf manenane, sne redues he sruural member negry and, f no orreed n me, may resul n loss of member and flgh safey. The general proedure of orroson removal n sruural members onsss n denfyng he affeed member hru arraf manenane manuals, removng he damage usng a proper proedure, vsually nspeng and performng nondesruve nspeons. One of he nondesruve ess arred ou s he hkness measuremen of a sruural affeed member. The evaluaon of remanng sa and fague srengh of he affeed par s performed by omparng he mnmum remanng hkness wh he allowable lms as saed n he arraf ehnal manuals. In he above menoned proedure, he seps relaed o remanng hkness measuremen by ulrason esng and resuls assessmen are he ral seps. They requre exreme are sne an onan several errors omng from no esmaed uneranes of he measuremen proedure, resulng n a wrong deson by ehnan or engneer. If he measuremen does no our wh relably, he aons o be aken may be ompleely wrong, affeng he flgh safey and nreasng he ndusry oss subsanally. In hs ase, s neessary he esablshmen of rera n order o ensure he merologal onfdene. Ths s he goal of he mehod proposed n hs work. II. ESTABLISMENT OF A CONFORMITY ZONE Aordng o Bennh (00), n several suaons, he ndusres are measurng wrong parameers wh hgh auray and are akng desons regardng he produ qualy n hs bass. The same problem ours n he arraf manenane ndusry, where he merology plays a relevan role durng all manenane proess, suh as damage evaluaon, une up of sysems, adjusmen of pars e. (SILVA, 01). On he oher hand, n he ndusres, nludng avaon, here s a very ommon prae of approvng pars when he measuremen s whn he spefaon zone or spefaon nerval, whh s defned as he zone where he values of he par haraers vary and nlude he spefaon lms (UNE-EN ISO 15-1, 1998); dsregardng he measuremen unerany IJET-IJENS Aprl 01 IJENS

2 END Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No:0 105 range of he nsrumen or sysem measurng. Ths prae an lead hs organzaon o wo ypes of problem: rejeon of pars OK o use, or approval of defe pars. The frs ase drely mpas he organzaon and he seond drely affes he usomer and, ndrely he organzaon. To mnmze hose problems, he sandard ISO 15-1 (UNE-EN ISO 15-1, 1998) presens a sysema o verfy ha a known haraers wll mee or no a spefaon, bu hs me, by onsderng no he spefaon lms only, bu also, he nfluene of he measuremen sysem, hrough he expanded measuremen unerany. Graphally, hs sysema s shown n Fg. 1. Analyzng he Fg. 1, an be verfed ha s dvded n wo phases (desgn and verfaon) and n four zones: spefaon zone or range; unerany area or range; onformane zone or range, and non-onformane zone or range. affeng he resul auray. Thus, several arplanes are beng repared due o rejeon of pars OK and ohers are beng reurned o serve wh defe pars. III. PROPOSED METODOLOGY In order o perform measuremens wh merologal onfdene, s proposed n hs paper, he mehodology, as shown n Fgure. One seleed he ulrason nsrumen, he nex sep s o albrae he respeve nsrumen, usng albraed referene sandard bloks. Afer he measuremens have been aken wh a repeon a leas fve mes a eah pon, should be used sasal rera for deeon of oulers, n order o oban a reals sample se. The nex sep s relaed o measuremen unerany deermnaon, usng he ISO GUM (GUM, 00) mehodology or usng Mone Carlo smulaon. In hs paper, he alulaon wll be arred ou by he wo mehods. The las sep onsss n esablsh a onformane zone for he referred measuremen. Calbrae he referene sandards a a RBC laboraory Calbrae he ulrason nsrumen Deermne he measuremen unerany (nhered) aordng o ISO GUM Carry ou he measuremens (a leas 5 n eah pon) Tune up he ulrason nsrumen aordng o skn nomnal hkness Idenfy n he produon drawng he nomnal hkness of he skn Corre he sysema errors of he measuremen (usng he erfae of albraon) Evaluae he resuls usng Chauvene, Dxon or Grubbs rera Deermne he measuremen unerany aordng o ISO GUM Par approved? Compare wh manufaurer allowable lms Esablsh he onformy nerval Fg. 1. Esablshmen of onformane and non-onformane zones aordng o UNE-EN ISO 15-1 (1998). Durng desgn phase, s esablshed he spefaon range whh presens as oulers he upper spefaon lm (USL) and he lower spefaon lm (LSL). owever, f he measured value falls n one of hese lms, should be onsdered he expanded measuremen unerany, whh reaes he onformane zone. In hs zone s guaraneed ha eran haraers wll mee he dmensonal desgn requremens; as well as he non-onformane zone whh s he area ha s no fulfllng he desgn requremens (ISO 80, 199). Through he orre mplemenaon of hs model, an be noed a noeable gan n he produ manufaurng n aordane wh he spefaon, mpang n rades and dspues (NIELSEN, 1999). In he avaon ndusry he oulers (USL and LSL) are defned hrough he produon drawng of he par and he ehnal manuals provded by he manufaurer. Currenly, when a hkness measuremen value (ulrason nspeon) falls n one of hose oulers, he expanded measuremen unerany s no usually onsdered durng he evaluaon of resuls. Then he onformane zone s wrongly reaed, Perform a repar or replae he par wh a new one (onsul he manufaurer) Fg.. Proposed mehodology for hkness measurng of aerospae pars by ulrason. IV. EXPERIMENTAL PROCEDURE The expermen smulaed a real suaon of remanng hkness measuremen by ulrason afer orroson removal from a wng skn of Arbus A10 arplane. To aomplsh hs expermen, was fabraed a es spemen wh he same hkness, maeral, fnshng and olerane as orgnal wng skn. Ths es spemen was blended ou, smulang a loal orroson removal. The Fgure shows he appearane of es spemen used for he expermen. I was randomly hosen fve pons nsde he blended ou area and wo pons ousde hs area (regon whou rework), refleng whh would be he skn nomnal hkness. I was arred ou fve repeons of ulrason measuremen n eah hosen pon. The Fgure shows he hosen pons for he expermen. The Table 1 shows he values found durng he measuremens. The Fgure 5 shows he ross seon appearane of he es spemen on he hosen pon (nsde he reworked area). The pon hosen pon for he approah of hs sudy was he number #, whh he average value s equal o 0,765 and IJET-IJENS Aprl 01 IJENS

3 0,765 0,787 Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No:0 106 he sandard devaon s equal o 0,005. Fg.. Tes spemen used on he expermen. Fg.. Pons hosen on he spemen for he expermen. Pon Measuremen REW ORK BOUNDARY LINE k l m j TABLE I ULTRASONIC MEASUREMENT RESULTS. j k l m n o p 1 s 0,760 0,767 0,769 0,765 0,767 0,78 0,78 nd 0,760 0,76 0,765 0,767 0,765 0,786 0,785 rd 0,759 0,766 0,76 0,769 0,760 0,78 0,78 h 0,760 0,76 0,76 0,768 0,76 0,78 0,785 5 h 0,760 0,76 0,76 0,768 0,76 0,78 0,785 Avg (μ),000 0,765 0,765 0,767 0,76 0,78 0,785 Sd dev. (σ) 0,0005 0,0011 0,005 0, ,0055 0, ,00055 (Values n nhes). Fg. 5. Tes spemen ross seon showng he reworked regon. A. Tes for Ouler Deeon The fve values analyss was performed usng he sofware known as ANAYSIS, onsderng he followng rera: Dxon, Chauvene and Grubbs. The Fg. 6 shows he home sreen of he ANALYSIS sofware used for he ess. n o p Orgnal skn onour before blend ou Fg. 6. ome sreen of ANALYSIS sofware. In all used rera (Dxon, Chauvene and Grubbs), he value 0,769 was dsarded, updang he average of values o 0,76 and he sandard devaon o 0, B. Mahemaal equaon o deermne he measuremen unerany hrough he ISO GUM mehodology Durng he hkness measuremen proess, several soures of unerany were onsdered for he expermen, sne hey an poenally nfluene wh relevane n he aepane evaluaon of he skn afer rework. The seps o deermne he measuremen unerany aordng o ISO GUM are presen as follows: Ls of measuremen unerany soures; Assgnmen of probably dsrbuon for eah soure of unerany; Sandard uneranes deermnaon; Coeffens of sensvy deermnaon; Combned unerany deermnaon; Effeve degrees of freedom deermnaon (number); Coverage faor deermnaon and Expanded unerany deermnaon. On he expermen, he man denfed soures of uneranes were: Sample sasal unerany ( A Unerany nhered from he ulrason nsrumen albraon ( Unerany due o ulrason nsrumen resoluon ( R Unerany due o he removal of referene emperaure (0ºC) ( The mahemaal equaon of hs suaon s gven by (1): Y A R The sample sasal unerany ( A ) (1), also known as ype IJET-IJENS Aprl 01 IJENS

4 Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No:0 107 A, s deermned hrough (): A n = sample sandard devaon, and n = number of measured pons. () r = ulrason nsrumen resoluon The las soure of unerany s relaed o he removal of referene emperaure n dmensonal measuremens (0ºC). For he soure ) was also arbued a reangular ( dsrbuon, as shown n (5). The unerany nhered from he ulrason nsrumen used n hs expermen, was obaned hrough he albraon of he same nsrumen n referene sandard bloks (saggered), as shown n Fgure 7. The referene sandard blok was prevously albraed a LAMDI (Laboraóro de Merologa Dmensonal do CEFET-RJ) usng a oordnae measurng mahne (CMM), raed o a Brazlan Calbraon Nework Lab (RBC). The unerany from he ulrason nsrumen ( U ) was equal o 0,0008 for k, 0. The Table presens ehnal spefaons of hs ulrason nsrumen. To oban he unerany nhered from he referene sandard, smply dvde he unerany value by he respeve overage faor, as per (). l op.. l op = nal hkness of he referene sandard; = hermal expanson oeffen of alumnum alloy 1 whh s equal o, º C and = varaon of emperaure n relaon o referene emperaure. The nex sep s ombne he ndvdual soures of sandard unerany, n order o oban he ombned unerany u ), as shown n (6) wh approxmaely 68% of onfdene. ( (5) u 1. A.. R. (6) Fg. 7. Referene sandard blok beng albraed for hs expermen. T ABLE II T ECNICAL SPECIFICATION OF ULTRASONIC INSTRUMENT USED IN TIS EXPERIMENT. Vendor Kraukramer Branson Model DMSTC Type Thkness gauge Resoluon 0,001 Nomnal range 0,008 o 5,00 Las albraon dae De/009 Transduer DA1 U k () The unerany due o ulrason nsrumen resoluon s gven by (), assgnng a reangular dsrbuon. r R. (),, = oeffens of sensvy for eah respeve soures of sandard unerany. For hs expermen, he oeffen values are all equal o 1, sne: 1, Y A Y Y R Y 1 Fnally, he expanded unerany (U ) s obaned, mulplyng he ombned unerany by a overage faor (k), aordng o (7), provdng 95% of onfdene approxmaely. U k. u To oban he overage faor, s neessary o alulae he number of effeve degrees of freedom. For a sasal varable an be nerpreed as he number of ndependen measuremens mnus he number of parameers already alulaed from hese daa (CABRAL, 00). The degrees of freedom ( ) are equal o ( n 1) when are assoaed o sandard devaon for a sample wh (n) repeons (unerany ype A) (ISO GUM, 00). For ype B (7) IJET-IJENS Aprl 01 IJENS

5 Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No:0 108 uneranes s usual o onsder ( ). Therefore, he number of effeve degrees of freedom ( eff ) an be esmaed based on he Welh-Saerhwae equaon, as gven n Eq. (8). One deermned he ) value, s requred o ( eff onsul he -Suden dsrbuon able and deermne he (k) value for 95,5% of onfdene. eff n u ( y) 1 u ( y) (8) D. Calulaon of measuremen unerany hrough Mone Carlo smulaon onsderng he 5 pons of measuremen Anoher possbly wdely used s onsderng he Mone Carlo smulaon o deermne he measuremen unerany. In hs expermen, was used he GUM WORKBENC sofware, n he aadem verson. Addng o he Mone Carlo smulaon module he values referred o eah soure of unerany, onsderng wo mllons of neraons and 95,5% of onfdene range, he unerany was equal o + 0,00. The Fg. 8 shows he generaed hsogram. C. Calulaon of measuremen unerany hrough ISO GUM onsderng he 5 pons measured Frsly onsderng he fve measuremens of pon #, no akng no aoun he sofware (ANALYSIS) applaon for ouler deeon, and followng he ISO GUM mehodology from () unl (8): A R l 0, , " n 5 U k 0,0008 0,000" 0,001 r 0, ".. op.. 0,765.0,00001.( 0) 0, " The emperaure average durng he measuremen was equal o ºC. u eff 0, ,000 0, , , " 0, , ,000 0, , ,97 The (k) value relaed o he number of effeve degrees of freedom s equal o,65. U k. u,65.0, ,001" I s very ommon n prae o arbue he value of overage faor (k), equal o,0. In hs ase, he expanded unerany would be equal o: U.0, ,00" Fg. 8. Mone Carlo smulaon resuls. E. Calulaon of measuremen unerany hrough ISO GUM onsderng he remanng pons only The four remanng pons of he sample are: 0,765 ; 0,76 ; 0,76 and 0,76. Applyng he ISO GUM (GUM, 008) mehodology, already desrbed n hs paper: A R 0, ,000088" n U 0,0008 0,000" k 0,001 r 0, ".. l op.. 0,76.0,00001.( 0) 0, " The emperaure average durng he measuremen was equal o ºC. u eff 0, ,000 0, , , " 0, , ,000 0, , ,19 The (k) value relaed o he number of effeve degrees of freedom s equal o,15, approxmaely. U k. u,15.0, ,001" Consderng he value of overage faor equal o, he measuremen unerany would be equal o a + 0, IJET-IJENS Aprl 01 IJENS

6 Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No:0 109 F. Calulaon of measuremen unerany hrough Mone Carlo smulaon onsderng he remanng pons only Applyng he Mone Carlo smulaon, onsderng he sample wh four remanng pons only, and usng wo mllons of neraons, he measuremen unerany s equal o + 0,0016, as shown n Fg. 9. Fg. 9. Mone Carlo smulaon resuls. Applaon of GUM Workbenh sofware for Mone Carlo smulaon, onsderng he measuremen wh pons only. V. RESULTS The Table presens he measuremen unerany, along wh her respeve overage faor, for eah suaon suded n Seon of hs paper. For he suaon where he pons are onsdered, usng he ISO GUM mehodology, was noed ha he sasal unerany onrbued wh 0,6% of expanded unerany, whle he ulrason nsrumen unerany onrbued wh 9,0%, he unerany due o he ulrason nsrumen resoluon wh 0,% and he unerany due o he emperaure wh 0,1% only. Moreover, onsderng he same mehodology appled o he 5 pons, was noed ha he sasal unerany onrbued wh 81,9% for he expanded unerany, whle he unerany due o he ulrason nsrumen onrbued wh 11,9% and he unerany due o he ulrason nsrumen resoluon wh 6,% only. There was no relevan onrbuon of unerany due o he emperaure n hs as e. The Table shows he onrbuon of he solaed soures of unerany n he wo suaons. TABLE III DIFFERENT CONSIDERATIONS OF EXPANDED MEASUREMENT UNCERTAINTY. Condon Analyal unerany for he 5 measured pons, usng he ISO GUM mehod Analyal unerany for he 5 measured pons, usng he ISO GUM mehod Measuremen unerany for he 5 measured pons, usng Mone Carlo smulaon Analyal unerany for he measured pons, usng he ISO GUM mehod Analyal unerany for he measured pons, usng he ISO GUM mehod Measuremen unerany for he measured pons, usng Mone Carlo smulaon Expanded unerany (k) + 0,00,65 + 0,00,00 + 0,00 _ + 0,001,15 + 0,001,00 + 0,00 _ TABLE IV INFLUENCE OF ISOLATED MEASUREMENT UNCERTAINTY CONTRIBUTION CONSIDERING AND 5 MEASURED POINTS. Measuremen unerany omponen 5 Pons Pons Sasal unerany 81,9% 0,6% Unerany nhered from he ulrason nsrumen 11,9% 9,0% Unerany due o ulrason nsrumen resoluon 6,% 0,% Unerany due o referene emperaure 0% 0,1% I s mporan o hghlgh ha he nomnal hkness of measured wng skn (alumnum alloy 0-T) s equal o 0,787" (+0,005"/-0,00"), orrespondng o a dmensonal olerane of 0,008. Relevan nformaon s ha he SRM Sruural Repar Manual (Arbus A10, 009) esablshes only ha a removal of 5% or 0,00 (whhever s less) from he wng lower skn nomnal hkness s allowed for damage removal, mananng he arplanes whn flgh safey requremens. In hs expermen, was appled he rera of aepng a removal up o 0,00" from nomnal hkness, sne hs rework remove less maeral han 5% of nomnal hkness. Thus, he mnmum remanng hkness aepable s equal o 0,767. VI. CONCLUSION Analyzng he Table, s noed ha, a frs, he use of he number of degrees of freedom s very mporan o deermne he overage faor (k) nsead of seng,0 n he analyal alulaon. In he measuremen unerany alulaon by ISO GUM (00), onsderng he 5 pons, he unerany was from + 0,00 ( k,65) o + 0,00 ( k,0). I shows ha here was a wrong derease of % approxmaely, sne he more reals value of he measuremen unerany s IJET-IJENS Aprl 01 IJENS

7 Inernaonal Journal of Engneerng & Tehnology IJET-IJENS Vol:1 No: ,00. Usng he same reasonng for he suaon where measured pons were used only, he measuremen unerany remans onsan and equal o + 0,001, for he overage faor of,15 and,00. Applyng Mone Carlo smulaon durng measuremen unerany deermnaon of 5 measured pons, an be noed ha here was no hange when ompared wh he analyal mehod, mananng he unerany also equal o + 0,00. In addon, onsderng he pons suaon, he unerany was from + 0,001, hrough he analyal mehod o + 0,00 by Mone Carlo smulaon, whh orresponds an nrease of 100%. Anoher relevan onluson s relaed o he applaon of ANALYSIS sofware. In hs ase, was deeed he pon 0,769 as ouler. Thus, he measuremen unerany was redued from + 0,00 o + 0,001 hrough analyal mehod, whh orresponds a reduon of 66,7%, provdng an expressve qualy mprovemen of resul. Also, he same reasonng for he Mone Carlo smulaon, showed an unerany reduon of,% approxmaely. Conernng he Table, an be verfed ha for he sample se of 5 pons, he sasal unerany onrbuon was 8% approxmaely; 6,8 mes hgher han he seond larges (1% approxmaely). Ths fa s resul of he sandard devaon nreasng, Ths s due o he nrease n he sandard devaon, aused by permanen pon of 0,769". Exludng hs pon, he onrbuon of sasal unerany praally dropped o half (0,6%), mahng he onrbuon of he unerany nhered from he ulrason nsrumen (9%). Takng no aoun he 5 measured pons and he analyal unerany alulaon, he measuremen resul was equal o (0,765+0,00), for ( k,65). owever, he mnmum remanng hkness aepable afer blend ou (no requrng and sruural renforemen) s equal o 0,767. Takng he average value of 0,765" only, he wng skn mus be renfored. owever, f he measuremen unerany s onsdered, here s a possbly of he rue value s whn he lower lm (0,76") unl he upper lm (0,768"), and beween 0,767" and 0,768". In hs ase, s no requred o renfore he sruure. Analyzng he sample se onanng he pons, he measuremen resul s equal o (0,76+0,001) for ( k,15). As he larger value ha he rue value an reah (for 95% of probably) s equal o 0,765", he deson o arry ou he renforemen s obvous. The omparson beween he usage of analyal mehod (ISO GUM) and Mone Carlo Smulaon for he hkness measuremen unerany shows ha he man dfferene beween wo mehods s relaed o he ype of dsrbuon arbued. In he analyal mehod, he ombned unerany s arbued o a normal dsrbuon; however s no neessarly rue, sne hs mehod works wh ndvdual soures of unerany wh dfferen probably dsrbuon, suh as normal, rangular and reangular. On he oher hand, when he Mone Carlo smulaon s appled, eah soure of unerany uses he respeve probably dsrbuon and a he end s obaned a resulan dsrbuon, normal or no. The lmaon of he Mone Carlo Smulaon refers o he proessng me, whh may be relevan dependng on he number of neraons. Through he analyss performed n hs work, s evden ha he applaon of hs proposed mehodology s requred, sne f any of he seps s no onsdered, he measuremen unerany alulaon wll be ompromsed, and, onsequenly, he resul obaned of he hkness measuremen by ulrason, an lead o msake aons, ompromsng he flgh safey and general manenane oss. Ths an our by wo manners: rework or renfore a sruure whh s whn spefaon zone or approve a dmenson whh he value s ou of spefaon lms (SILVA, 01). When usng he mehodology, s requred o aomplsh a ral analyss of he avalable measuremen proess, so ha an be deermned he number of measuremen (repeons), he due dae of ulrason nsrumen albraon, measuremen mode, ouplng ype e. An dea for fuure works s o aomplsh new sudes regardng he measuremen uneranes relaed o hkness measuremen by ulrason, akng no aoun new poenal soures of unerany suh as baery harge varaon of ulrason nsrumen, measured surfae roughness varaon, quany of ouplng used, operaor experene e. REFERENCES [1] AIRBUS, A10 Sruural Repar Manual, Man Skns, Allowable Damages, Chaper , Germany, De 009. [] BENNIC, P. Geomeral measuremens. Mero Trade Workshop raeably and measuremen unerany n esng, Berln, 00. [] FAA, U. S. Deparmen of Transporaon, Ulrason Tesng for Arraf, USA, [] ISO 15-1, 1998, Geomeral Produ Spefaons (GPS) Inspeon by measuremen of workpees and measurng equpmen Par 1: Deson rules for provng onformane or nononformane wh spefaons. [5] ISO 80. Gesón de la aldad y asegurameno de la aldad. Voabuláro, Buenos Ares, 199. [6] ISO GUM - Gua para a expressão da nereza de medção Terera edção braslera em língua poruguesa Ro de janero: ABNT, INMETRO, 00. [7] NIELSEN,. S. ISO Deson rules good or bad? Naonal onferene of sandards laboraores. Workshop & symposum, [8] SILVA, B. C. A. Esudo das Inerezas na Medção de Espessura por Ulrassom em Peças Aeronáuas. Dsseração de Mesrado - Cenro Federal de Eduação Tenológa Celso Sukow da Fonsea, Ro de Janero, Brazl, IJET-IJENS Aprl 01 IJENS