ISO 22181-2021 PDF

Full title and description

Aerospace fluid systems and components — Variable displacement hydraulic motors — General specifications (ISO 22181:2021). This International Standard specifies general design and test requirements for variable-displacement uni‑directional and bi‑directional hydraulic motors intended for aircraft hydraulic systems (pressure rating up to 35 000 kPa / 5 000 psi).

Abstract

Establishes the general requirements (design and test) for variable‑displacement hydraulic motors used in aerospace applications. Covers primary and secondary function motors; excludes actuators with internal rotation angle limits and low‑speed motors. Intended to be used alongside a detail specification specific to each application.

General information

• Status: Published.
• Publication date: 9 February 2021 (published February 2021).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 49.080 (Aerospace fluid systems and components).
• Edition / version: Edition 1 (2021).
• Number of pages: 38 pages.

Scope

Specifies general requirements for variable‑displacement hydraulic motors suitable for aircraft hydraulic systems up to 35 000 kPa (5 000 psi). Includes both uni‑directional and bi‑directional motors, addressing design and test provisions for primary and secondary function motors. Excludes actuators that incorporate internal rotation angle limits and low‑speed motors. The standard is intended to be applied together with detail specifications tailored to particular applications.

Key topics and requirements

• General design requirements for variable‑displacement hydraulic motors (mechanical, hydraulic interfaces and functional classification).
• Performance and pressure ratings (suitable for systems up to 35 000 kPa / 5 000 psi).
• Test and verification requirements (endurance, leakage, performance testing as described within the standard and referenced detail specifications).
• Classification of primary vs. secondary function motors and related requirements.
• Exclusions and limitations (actuators with internal rotation angle limits; low‑speed motors).
• Requirement to use this general specification together with application‑specific detail specifications.

Typical use and users

Used by aerospace OEMs, component and subsystem designers, hydraulic‑system engineers, qualification and test laboratories, suppliers of aircraft hydraulic motors, procurement teams and certification authorities specifying or verifying hydraulic motor performance and compliance for aircraft and space‑vehicle applications. Also referenced by technical committees and standards developers working on related aerospace fluid‑power standards.

Related standards

Standards from the same ISO technical area (ISO/TC 20/SC 10) are typically referenced together. Examples include standards for fixed (constant) displacement hydraulic motors and hydraulic power transfer units — e.g. ISO 9206 (fixed/constant displacement hydraulic motors — general specifications) and ISO 22089 (hydraulic power transfer units — general specifications). Users should consult the detail specifications and other ISO aerospace hydraulics standards for complete procurement and qualification requirements.

Keywords

variable displacement hydraulic motor; aerospace hydraulics; aircraft hydraulic systems; hydraulic motor design; hydraulic motor testing; ISO 22181; ISO/TC 20/SC 10; 35 000 kPa; 5 000 psi.

FAQ

Q: What is this standard?

A: ISO 22181:2021 is an international standard titled "Aerospace fluid systems and components — Variable displacement hydraulic motors — General specifications" that defines general design and test requirements for variable‑displacement hydraulic motors used in aircraft hydraulic systems.

Q: What does it cover?

A: It covers general requirements (design and test) for uni‑directional and bi‑directional variable‑displacement hydraulic motors suitable for aircraft systems up to 35 000 kPa (5 000 psi). It does not cover actuators with internal rotation angle limits or low‑speed motors and is intended to be used with application‑specific detail specifications.

Q: Who typically uses it?

A: Aerospace OEMs, hydraulic system designers, component manufacturers, test and qualification laboratories, procurement teams and certification bodies involved in specifying, supplying or verifying aircraft hydraulic motors.

Q: Is it current or superseded?

A: ISO 22181:2021 was published on 9 February 2021 and is the first edition. It is published and (per ISO lifecycle) under systematic review on a five‑year cycle (review activity noted toward 2026). Users should check the official ISO catalogue or national standards bodies for any amendments, confirmations or revisions after 2021.

Q: Is it part of a series?

A: It forms part of the ISO work on aerospace fluid systems and components developed by ISO/TC 20/SC 10 and is commonly used alongside related aerospace hydraulic standards (for example ISO 9206 for fixed displacement motors and ISO 22089 for power transfer units).

Q: What are the key keywords?

A: Variable displacement hydraulic motor; aerospace hydraulics; hydraulic motor testing; aircraft hydraulic systems; ISO 22181; design requirements; test requirements; 35 000 kPa (5 000 psi).