ISO 11218:2017

Overview

ISO 11218:2017, Aerospace - Cleanliness classification for hydraulic fluids, specifies a cleanliness classification for hydraulic fluids used in aeroplanes, helicopters and space vehicles. Rather than creating a standalone new test method, ISO 11218:2017 adopts the contamination classification contained in SAE AS4059F as the de facto ISO classification and applies a specific modification: adding ISO 5884 as a referenced method for system sampling and particle measurement. The document provides the formal identification statement to show compliance and establishes consultation arrangements with SAE for future revisions.

Key Topics

• Scope: Cleanliness classification for hydraulic fluids across aerospace platforms (airborne and space).
• Adoption of AS4059F: Requirements and classification criteria are specified by SAE AS4059F; ISO 11218:2017 references AS4059F as the normative basis.
• Reference addition: ISO 5884 is added as a normative reference for methods of system sampling and measuring solid particle contamination.
• Compliance statement: The standard provides the required identification text: “Hydraulic fluid cleanliness classifications in accordance with ISO 11218.”
• Governance: ISO/TC 20/SC 10 is responsible for the standard and will be consulted on any AS4059F revisions.

Applications

ISO 11218:2017 is practical for organizations and activities that require controlled hydraulic-fluid cleanliness to ensure reliability and safety in aerospace systems:

• Aerospace manufacturers and integrators: specify cleanliness levels in procurement documents, supplier contracts and system design requirements.
• Maintenance, repair and overhaul (MRO) providers: establish acceptable cleanliness for replacement fluids, system flushing, and post-service verification.
• Quality and reliability engineers: implement contamination control programs, process audits and acceptance criteria for hydraulic systems.
• Test laboratories: apply ISO 5884 sampling and particle measurement methods alongside AS4059F classification for reporting cleanliness levels.
• Regulatory and certification bodies: reference ISO 11218:2017 to harmonize contamination control expectations across programmes.

Related Standards

• SAE AS4059F - Aerospace fluid power - Contamination classification for hydraulic fluids (normative basis adopted by ISO 11218:2017).
• ISO 5884 - Methods for system sampling and measuring the solid particle contamination of hydraulic fluids (added reference in ISO 11218:2017).

ISO 11218:2017 is essential when you need an internationally recognized cleanliness classification for hydraulic fluids in aerospace contexts, ensuring consistent contamination control, procurement clarity, and interoperability between manufacturers, suppliers and maintenance organizations. Keywords: ISO 11218:2017, hydraulic fluid cleanliness, aerospace hydraulic fluids, contamination classification, AS4059F, ISO 5884.