SIST EN 3665:2001

• Abstract:

  This standard specifies a test method for the determination of the protective action of coatings of paints or varnishes against filiform corrosion on aluminium alloys.

• Status: Published
• Publication Date: 31-Dec-2000
• ICS: 49.025.20 - Aluminium
• ICS: 49.040 - Coatings and related processes used in aerospace industry
• Technical Committee: SS SPL - Technical Board for the general field
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jan-2001
• Due Date: 01-Jan-2001
• Completion Date: 01-Jan-2001
• Ref Project: EN 3665:1997 - Aerospace series - Test methods for paints and varnishes - Filiform corrosion resistance test on aluminium alloys

• Referred By: SIST EN 4704:2012 - Aerospace series - Tartaric-Sulphuric-Acid anodizing of aluminium and aluminium wrought alloys for corrosion protection and paint pre-treatment (TSA)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4688:2021 - Aerospace series - Paints and varnishes - Corrosion resistant chromated two-components room temperature curing epoxy primer - High corrosion resistance for military application
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 21227-4:2009 - Paints and varnishes - Evaluation of defects on coated surfaces using optical imaging - Part 4: Evaluation of filiform corrosion (ISO 21227-4:2008)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4827:2017 - Aerospace series - Hexavalent chromium free anodizing of aluminium and aluminium alloys
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4827:2019 - Aerospace series - Hexavalent chromium free anodizing of aluminium and aluminium alloys
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4827:2024 - Aerospace series - Hexavalent chromium free anodizing of aluminium and aluminium alloys
• Effective Date: 28-Jan-2026

Overview

EN 3665:1997 (CEN) - "Aerospace series - Test methods for paints and varnishes - Filiform corrosion resistance test on aluminium alloys" specifies a standardized test method to determine the protective action of paint and varnish coatings against filiform corrosion on aluminium alloys. The standard is intended for coatings and related processes used in the aerospace industry and provides a repeatable way to evaluate how well a coating resists filamentary corrosion initiated at coating defects or along scribed paths.

Key topics and requirements

The standard focuses on the following technical topics and requirements (as summarized from the scope and title):

• Scope: Measurement of filiform (filamentary) corrosion resistance specifically for coatings applied to aluminium alloys in aerospace applications.
• Specimen preparation: Requirements for substrate selection, surface preparation and coating application to ensure consistent, comparable test samples.
• Test initiation: Controlled initiation of filiform corrosion (e.g., by scribing or creating defects) to assess coating performance under realistic failure modes.
• Exposure conditions: Use of specified environmental or humidity exposure protocols to promote filamentary corrosion propagation in a reproducible way.
• Assessment and evaluation: Criteria and methods for visual inspection, measurement of filament length/density, and ranking or classification of coating protective action.
• Reporting: Standardized test reporting to ensure traceability and comparability between laboratories and suppliers.

Note: EN 3665:1997 defines the test method and evaluation approach rather than prescribing specific coating formulations.

Applications

EN 3665 is practically valuable for professionals involved in aerospace materials and coatings, including:

• Coating manufacturers validating filiform corrosion resistance of new paint and varnish systems for aluminium parts.
• Aerospace OEMs and suppliers performing quality control and acceptance testing of coated aluminium components.
• Materials and corrosion engineers conducting R&D on protective coatings and surface treatments.
• Accredited test laboratories providing certified corrosion testing services for aerospace contracts.
• Procurement and compliance teams demonstrating that coatings meet recognized aerospace test methods.

Using this CEN standard helps reduce in-service corrosion risks, improves durability of aluminium airframe components, and supports claims about coating longevity and protective performance.

Related standards

For comprehensive corrosion control programs, users typically refer to other aerospace and corrosion test standards (surface preparation, salt spray, adhesion tests). When applying EN 3665, coordinate with applicable aerospace specifications and materials standards relevant to aluminium alloys and coating systems.

Keywords: EN 3665:1997, filiform corrosion resistance, aluminium alloys, aerospace coatings, test methods for paints and varnishes, CEN standard.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aerospace series - Test methods for paints and varnishes - Filiform corrosion resistance test on aluminium alloysLuft- und Raumfahrt - Prüfverfahren für Anstrichstoffe - Prüfung der Beständigkeit gegen Filiformkorrosion von AluminiumlegierungenSérie aérospatiale - Méthodes d'essai pour peintures et vernis - Essai de résistance a la corrosion filiforme sur alliage d'aluminiumAerospace series - Test methods for paints and varnishes -
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