268 ISO International Standard ANsl Internct Doc Sect Aircraft - Mechanical and electromechanical indicators - General requirements Aeronefs -- Instruments de bord mécaniques et eélectromecaniques -- Caracteristiques generales First edition -- 1980-07-15 AUG 0 1 1980 UDC 629.7.054 Ref. No. 1ISO 268-1980 (E) ISO 268-1980 (E) Descriptors : aircraft equipment, aircraft instruments, electrical equipment, indicating instruments, graduations, specifications, video signals, marking. Price based on 5 pages Copyright International Organization for Standardization d without license from IHS Not for Resale Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards institutes (iso member bodies). The work of developing Inter- national Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with IsO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as international Standards by the ISo Council. International Standard ISO 268 was developed by Technical Committee ISO/TC 20, Aircraft and space vehicles, and was circulated to the member bodies in January 1978. Australia Germany, F. R. Spain Sweden Austria India Belgium Italy Turkey Brazil Japan United Kingdom Canada Mexico USA USSR Chile Poland Romania Yugoslavia Czechoslovakia France South Africa, Rep. of The member body of the following country expressed disapproval of the document on technical grounds : Netherlands This international Standard cancels and replaces ISO Recommendation R 268-1962, of which it constitutes a technical revision. @ International Organization for Standardization, 1980 Printed in Switzerland Copyright International Organization for Standardization Not for Resale g permitted without license from IHS INTERNATIONAL STANDARD ISO 268-1980 (E) Aircraft - Mechanical and electromechanical indicators s - General reguirements Scope and field of application The design and construction of the indicator case shall be 3.4 such that the indicator's specified performance is unaffected This International Standard states the requirements which are when the indicator, instailed in accordance with the relevant generally applicable to mechanical and electromechanical in- declarations, is subjected to the test for drip-proof equipment dicators for use in aircraft. It is to be read in conjunction with in accordance with ISo 2655, and to tests for resistance to specifications for individual indicators. other fluids, as required by the individual specification. For the purpose of this International Standard, an indicator is regarded as a unit primarily concerned with the visual display of The legibility of the indicator shall not be significantly af- 3.5 information. fected by any misting inside the glass under the conditions of use for which it is deciared. References 2 Iso 2655, Environmental tests for aircraft equipment - Part 5A hermetically-sealed indicator shall withstand the seal- 3.6 2.5 : Waterproofness. ing test specified in IEC Publication 68-2-17. IEc Publication 68-2-17, Basic environmental testing pro- cedures - Part 2. 1 : Test Q : Sealing. 3.7 if a pressure-measuring indicator is vented to the sur- rounding atmosphere, the vent shall not affect the performance 3 Cases for indicators of the indicator. It shail be suitably screened to prevent the ingress of dust and sand. Preferably, the vent should be pro- 3.1 The size and type of the finished indicator case shall be tected against inadvertent ciosure and located at approximately the lowest point connecting with the interior when the indicator declared by the manufacturer in sufficient detail to facilitate is in the normal position. subse