SIST EN 3033:2008

Overview

SIST EN 3033:2008 is a European standard developed by CEN that specifies the requirements for aerospace-grade self-locking hexagonal nuts with captive washers. These nuts are manufactured from heat-resisting steel FE-PA2601 (commonly known as A286) and are uncoated, designed to withstand extreme conditions up to 425 °C. The standard emphasizes critical dimensions, mechanical properties, and performance characteristics essential for aerospace applications, ensuring reliability and safety in high-temperature environments.

Key Topics

• Scope and Application
  Defines the dimensions and mechanical characteristics of self-locking hexagonal nuts with captive washers in heat resisting steel FE-PA2601 for use in aerospace components. Designed to sustain maximum test temperatures of 425 °C, this standard ensures nuts perform reliably under demanding thermal stress.

• Material Specification
  Nuts are made from heat resisting steel FE-PA2601 (A286) conforming to EN 2399, EN 3638, and EN 3639 standards. Washers are either made from the same steel grade or FE-PA3601, with passivation applied to washers according to EN 2516 to prevent corrosion.

• Design and Dimensions
  The standard specifies precise nut dimensions, tolerances, and masses. The MJ thread profile follows ISO 5855-1 and ISO 5855-2. Key dimensional aspects include minimum and maximum values for across flats, thickness, and thread engagement to ensure compatibility and mechanical integrity.

• Locking Mechanism
  The nuts are self-locking via an out-of-round form in the thread zone, which maintains secure fastening in aerospace assemblies subjected to vibration and thermal cycling.

• Marking and Traceability
  In compliance with EN 2424, nuts must be clearly marked to ensure traceability and regulatory conformity within aerospace manufacturing and maintenance processes.

• Product Qualification
  The qualification process follows EN 9133 guidelines and must meet the technical specification as outlined in EN 3152 to guarantee performance standards under typical aerospace operational conditions.

Applications

SIST EN 3033:2008 nuts are critical components in aerospace engineering, where fasteners must resist high temperatures and mechanical stresses. Typical applications include:

• Aircraft Engine Assembly
  These nuts are used in engines where operating temperatures can reach up to 425 °C, maintaining structural integrity and safety.

• Airframe Fastening
  Their self-locking feature prevents loosening due to vibrations during flight, ensuring secure fastening in critical airframe joints.

• High-Temperature Aerospace Systems
  Suitable for other aerospace systems exposed to heat and stress, such as thermal protection panels and exhaust assemblies.

The heat-resisting properties and precise dimensioning make these nuts essential for durability and long-term reliability in aerospace fastener applications.

Related Standards

• ISO 5855-1 & ISO 5855-2 - General requirements and limit dimensions for aerospace MJ threads used in nuts and bolts.
• EN 2399 - Specification for heat resisting steel FE-PA92-HT bars used in forged bolts.
• EN 2424 - Marking requirements for aerospace products ensuring traceability.
• EN 2516 - Passivation and corrosion resistance treatment for stainless steels and nickel alloys.
• EN 3152 - Technical specifications for similar uncoated or silver-plated hexagonal nuts in FE-PA2601 steel.
• EN 3638 & EN 3639 - Material specifications for heat resisting steel FE-PA2601 in various forms.
• EN 9133 - Quality management and qualification procedures for aerospace standard parts.

Keywords: aerospace nuts standard, SIST EN 3033:2008, self-locking hexagonal nuts, heat resisting steel nuts, FE-PA2601 A286 nuts, captive washer nuts, high-temperature aerospace fasteners, MJ thread nuts, aerospace fastener dimensions, aerospace grade nuts, uncoated heat resistant nuts, CEN aerospace standards.