ISO 18387:2019

INTERNATIONAL ISO
STANDARD 18387
First edition
2019-09
Aerospace — Linear hydraulic utility
actuator — General specifications
Série aérospatiale — Actionneur hydraulique linéaire à usage général
— Spécifications générales
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 General requirements . 7
4.1 Order of precedence . 7
4.2 Hydraulic system characteristics . 7
4.3 Qualification . 7
4.4 Airworthiness requirements. 7
5 Functional requirements . 7
5.1 General . 7
5.2 Actuator type . 7
5.3 Features incorporated within the utility actuator . 8
5.4 Hydraulic fluid . 8
5.5 Performance . 8
5.5.1 General. 8
5.5.2 Performance cases . . 8
5.5.3 Leakage . 9
5.5.4 Seal and scraper friction .10
5.5.5 End of travel snubbing .10
5.5.6 Utility actuator locking means .10
5.6 Endurance .12
5.6.1 General.12
5.6.2 Duty cycle .12
5.6.3 Endurance test .12
5.7 Fluid and ambient temperature .12
5.8 Fluid cleanliness .13
5.8.1 Operation .13
5.8.2 Malfunction . .13
5.8.3 Equipment delivery .13
5.9 Environmental requirements .13
6 Detail design requirements .14
6.1 General .14
6.2 Prevention of incorrect assembly .14
6.3 Standard parts .14
6.4 Maintainability features .15
6.5 Seals and scrapers .15
6.5.1 General.15
6.5.2 Gland surface finishes.15
6.5.3 Static seals .15
6.5.4 Dynamic seals .16
6.5.5 Scraper rings .16
6.5.6 Back-up rings .16
6.5.7 Lead in chamfers .17
6.6 Fluid porting through interfacing surfaces .17
6.7 Lubrication of hydraulic elements .17
6.8 Orifices .17
6.9 Retainer (snap) rings .17
6.10 Spring rings .18
6.11 Secondary locking .18
6.12 Drainage .18
6.13 Drillings .18
6.14 Fillet radii .18
6.15 Rod ends .18
6.16 Bearings .19
6.16.1 General.19
6.16.2 Lubrication .19
6.16.3 Anti-roll feature .20
6.17 Threaded components .20
6.18 Electro-conductive bonding .20
6.19 Marking .20
6.19.1 Nameplate .20
6.19.2 Fluid identification .21
7 Strength requirements .21
7.1 Hydraulic .21
7.1.1 DOP definition .21
7.1.2 Proof pressure .21
7.1.3 Ultimate (burst) pressure .21
7.1.4 Impulse fatigue .21
7.1.5 Operation at full flow relief pressure .
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