EN 6140:2020

• Abstract:

  This document specifies the dimensions, tolerances and required characteristics of protective plugs,; non-metallic, for NAS1760 fitting ends and AS33649 boss ports to seal fluid ports during transportation; and storage in order to prevent;  contamination by moisture, fluids, chemicals and particles,;  spillage inside package or aircraft section,;  port and pipe end damages and;  port and pipe clogging due to plug ingestion.; Because of the cleanliness requirements, parts shall only be used once.

• Status: Published
• Publication Date: 29-Sep-2020
• Withdrawal Date: 30-Mar-2021
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 3/S 3 - Hydraulics
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 30-Sep-2020
• Completion Date: 30-Sep-2020
• Ref Project: SIST EN 6140:2020 - Aerospace series - Plug, protective, non-metallic, for NAS1760 fitting ends and AS33649 boss ports

• Refers: ISO 2768-1:1989 - General tolerances — Part 1: Tolerances for linear and angular dimensions without individual tolerance indications
• Effective Date: 10-Jun-2026
• Refers: ISO 3161:1999 - Aerospace — UNJ threads — General requirements and limit dimensions
• Effective Date: 10-Jun-2026
• Refers: ISO 11218:2017 - Aerospace — Cleanliness classification for hydraulic fluids
• Effective Date: 09-Feb-2026
• Refers: ISO 9940:2015 - Aerospace series — Fluid, hydraulic, phosphate ester-base, fire resistant — Technical specification
• Effective Date: 09-Feb-2026
• Refers: EN 2424:2008 - Aerospace series - Marking of aerospace products
• Effective Date: 28-Jan-2026
• Refers: EN 10244-1:2009 - Steel wire and wire products - Non-ferrous metallic coatings on steel wire - Part 1: General principles
• Effective Date: 28-Jan-2026
• Refers: EN 12631:1999 - Fruit and vegetable juices - Enzymatic determination of D- and L-lactic acid (lactate) content - NAD spectrometric method
• Effective Date: 28-Jan-2026

Overview

EN 6140:2020 - Aerospace series - Plug, protective, non‑metallic, for NAS1760 fitting ends and AS33649 boss ports - is a CEN European standard specifying the design, materials and quality requirements for non‑metallic protective plugs used to seal hydraulic/fluid ports in aerospace applications. The standard defines dimensions, tolerances, performance and packaging to prevent contamination, spillage and port damage during storage and transport.

Key topics and requirements

• Purpose: Seal NAS1760 fitting ends and AS33649 boss ports to prevent moisture, fluids, chemicals, particles, spillage and plug ingestion.
• Configuration & dimensions: Detailed geometry, tolerances and mass are defined (refer to Figure 1 / Table 2 in the standard). Unspecified linear tolerances: ISO 2768‑m.
• Material & colour: Specified as high‑density polyethylene (HD‑PE) with density 0.940–0.970 and Melt Flow Index 7.5–15.0. Colour examples: red (AMS‑STD‑595 references).
• Environmental & mechanical limits:
  • Proof pressure: 100 kPa (1 bar).
  • Storage/transport temperature: −54 °C to 85 °C.
  • Installation/removal at room temperature (25 ± 10) °C.
• Cleanliness: Parts must meet ISO 11218 class 7 or better; because of cleanliness requirements plugs are intended for single use.
• Sealing & testing:
  • Sealing surfaces must mate consistently with associated fitting dimensions (illustrated in the standard).
  • Qualification: 3 specimens per size for general tests; first article inspection: 6 specimens tested at proof pressure for 3 minutes.
• Marking & packaging:
  • Marking per EN 2424 (part designation + manufacturer/trademark/CAGE code).
  • Individual chlorine‑free packaging, protected against contamination and damage; cleanliness maintained until package opening.
• Manufacturing & inspection:
  • Manufacturers should have an aerospace quality management system (e.g., EN 9100).
  • Supplier responsible for inspection unless contract specifies otherwise.

Applications and who uses it

• Primary use: Temporary sealing of hydraulic and fluid ports on aircraft components, hose assemblies and pipes during manufacturing, storage, shipment and maintenance.
• Typical users:
  • Aerospace OEMs and suppliers producing NAS1760 / AS33649 interfaces
  • MRO organizations and aircraft maintenance teams
  • Quality, procurement and logistics engineers specifying protective plugs for transport and storage
  • Component manufacturers qualifying plug designs and materials

Related standards

• EN 2424 (marking), EN 6079 (flareless fittings), ISO 2768, ISO 3161, ISO 9940 (phosphate ester hydraulic fluids), ISO 11218 (cleanliness), AS4395B, AS5202A, EN 9100 (quality management).

Keywords: EN 6140:2020, protective plug, non‑metallic plug, NAS1760, AS33649, aerospace hydraulic ports, HD‑PE plug, sealing, cleanliness, proof pressure, packaging.