ASTM_F_2696_-_14.pdf

Designation:F269614Standard Practice forInspection of Aircraft Electrical Wiring Systems1This standard is issued under the fixed designation F2696;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers basic inspection procedures forelectrical wiring interconnect systems for aircraft electricalwiring systems.1.2 This practice is not intended to replace any instructionsfor continued airworthiness published by the aircraft or acces-sory manufacturer or type design holder.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 Military Standard:2MIL-C-85049 Connector Accessories,Electrical,GeneralSpecification for2.2 FAA Guidance Material:3FAA Advisory Circular 33.4-3 Instructions for ContinuedAirworthiness;Aircraft Engine High Intensity RadiatedFields(HIRF)and Lightning Protection Features2.3 SAE Documents:4SAE ARP1870 Aerospace Systems Electrical Bonding andGrounding for Electromagnetic Compatibility and SafetySAE Aerospace ARP5583 Guide to Certification of Aircraftin a High Intensity Radiated Field(Hirf)Environment3.Terminology3.1 Acronyms:3.1.1 EWISelectrical wiring interconnection system3.1.2 HIRFhigh-intensity radiated fields3.1.3 ICAinstructions for continued airworthiness3.1.4 LRUline-replaceable unit3.1.5 MSmilitary standard3.1.6 MTBFmean time between failures3.1.7 PTFEpolytetrafluoroethylene3.1.8 RFradio frequency3.1.9 STCsupplemental type certificate(Federal AviationAdministration)4.Significance and Use4.1 The term“electrical system”as used in this practicemeans those parts of the aircraft that generate,distribute,anduse electrical energy,including their support and attachments.4.2 The satisfactory performance of an aircraft is dependentupon the continued reliability of the electrical system.4.3 Damaged wiring or equipment in an aircraft,regardlessof how minor it may appear to be,cannot be tolerated.It is,therefore,important that maintenance be accomplished usingthe best techniques and practices to minimize the possibility offailure.4.4 When inspecting and evaluating EWIS,improperwiring,routing,or repairs shall be corrected regardless of theorigin of the error.4.5 This practice is not intended to supersede or replace anygovernment specification or specific manufacturers instructionregarding electrical system inspection and repair5.Causes of Wire Degradation5.1 The following are considered the principal causes ofwiring degradation and should be used to help focus mainte-nance programs:5.1.1 VibrationHigh-vibration areas tend to acceleratedegradation over time resulting in“chattering”contacts andintermittent symptoms.High vibration of tie-wraps or stringties can cause damage to insulation.In addition,high vibrationwill exacerbate any existing wire insulation cracking.1This practice is under the jurisdiction of ASTM Committee F39 on AircraftSystems and is the direct responsibility of Subcommittee F39.02 on Inspection,Maintenance,and Repair.Current edition approved May 1,2014.Published June 2014.Originallyapproved in 2008.Last previous edition approved in 2008 as F2696 08.DOI:10.1520/F2696-14.2Available from the U.S.Government Printing Office,Superintendent ofDocuments,Stop:SSOP,Washington,DC 20402-0001.3Available from Federal Aviation Administration(FAA),800 IndependenceAve.,SW,Washington,DC 20591,http:/www.faa.gov.4Available from Society of Automotive Engineers(SAE),400 CommonwealthDr.,Warrendale,PA 15096-0001,http:/www.sae.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.2 MoistureHigh-moisture areas generally acceleratecorrosion of terminals,pins,sockets,and conductors.Note thatwiring installed in clean,dry areas with moderate temperaturesappears to hold up well.5.1.3 MaintenanceScheduled and unscheduled mainte-nance activities,if done improperly,may contribute to long-term problems and degradation of wiring.Metal shavings anddebrishavebeendiscoveredonwirebundlesaftermaintenance,repair,or alteration work has been performed.Extra attention shall be given to EWIS inspections aroundareas of previous aircraft maintenance,repair,or alterations.5.1.4 RepairSince wire splices are more susceptible todegradation,arcing,and overheating,extra care shall be givenwhen inspecting repaired wiring.5.1.5 AlterationsAlterations