Overview - What ISO 18387:2019 covers
ISO 18387:2019 defines the general requirements for linear hydraulic utility actuators used in aerospace flight-vehicle hydraulic systems up to 35 000 kPa (5 000 psi). It provides a baseline of design, performance and test requirements for utility actuators and is intended to be used together with a detail specification specific to each application. The standard clarifies scope (for example, brake pistons and landing‑gear bogie pitch trimmers are excluded as specialist devices) and supports airworthiness and qualification activities for aerospace hydraulic actuators.
Key technical topics and requirements
ISO 18387 organizes requirements across functional, strength, endurance and design areas. Key topics include:
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Functional requirements
- Actuator types and features incorporated within utility actuators
- Hydraulic fluid compatibility and cleanliness
- Performance cases, leakage limits, seal and scraper friction
- End‑of‑travel snubbing and locking means
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Endurance and testing
- Duty cycle definition and endurance test expectations
- Impulse fatigue and endurance verification under representative conditions
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Strength and structural requirements
- Hydraulic proof pressure and ultimate (burst) pressure limits
- Combined hydraulic and structural loading, buckling, limit and ultimate loads
- Port strength, vibration and mechanical fatigue considerations
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Detail design and construction
- Seals, scrapers, back‑up rings, gland finishes and lead‑in chamfers
- Bearings, rod ends, threaded components, retainer and spring rings
- Corrosion protection, materials selection and marking/nameplate requirements
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Environmental and airworthiness
- Fluid and ambient temperature ranges, environmental testing and airworthiness documentation
Practical applications - who uses this standard
ISO 18387 is practical for:
- Aerospace actuator designers creating linear hydraulic utility actuators
- Systems and propulsion engineers specifying actuator requirements for flight systems
- Manufacturers and suppliers preparing detail specifications, test plans and product qualification
- Quality, test laboratories and certification authorities assessing compliance (proof pressure, endurance, leakage, fatigue)
- Procurement and maintenance teams referencing standard requirements during selection, inspection and overhaul
Related standards and usage
ISO 18387 is intended to be used alongside application‑specific detail specifications and other aerospace standards covering hydraulic fluids, sealing materials, corrosion protection and airworthiness certification. When specifying a component, reference ISO 18387 for general actuator requirements and add application‑specific documents to define duty cycle, interfaces and installation criteria.
Keywords: ISO 18387, linear hydraulic utility actuator, aerospace actuator specifications, hydraulic systems, endurance test, seal and scraper, proof pressure, actuator design.