HL70-6 - Textron Aviation OEM Hilock Collar

HL70-6 – Textron Aviation OEM Hi-Lok Collar

Available now on the Airparts.aero Marketplace.

Overview

The HL70-6 is a genuine OEM, flight-critical Hi-Lok collar, a key component of the high-strength, two-piece Hi-Lok fastening system specified for use on Textron Aviation aircraft. This collar is engineered to be paired with a corresponding -6 (3/16") diameter Hi-Lok pin, creating a lightweight, high-temperature, and vibration-resistant structural joint. The hallmark of this system is the collar's frangible hex wrenching element, which shears off at a predetermined torque value during installation, ensuring a precise and consistent preload is achieved every time. Manufactured from high-strength A-286 CRES, the HL70-6 is a modern fastening solution for primary airframe structures.

Key Features

• Automatic Torque Control: The collar features an external hex portion designed to shear off when the correct installation preload is reached. This removes operator-to-operator variability and guarantees that every fastener in a joint is clamped with the precise, engineered force.
• High-Temperature A-286 CRES Construction: Fabricated from A-286, an iron-nickel-chromium superalloy. This material provides excellent strength and creep resistance at elevated temperatures (typically up to 900°F), making it suitable for firewall-forward and other high-temperature applications.
• Vibration Resistance: The Hi-Lok system creates a high-preload joint that is exceptionally resistant to loosening under the severe vibration and cyclical loads of flight, ensuring long-term structural integrity.
• Silver Plated Finish: Typically finished with a silver plating which acts as a dry film lubricant. This is essential for preventing galling between the high-strength CRES threads of the collar and pin, ensuring a smooth, accurate torque-up sequence before the hex shears.
• Industry Standard: As a standard part used and specified by Textron Aviation, it guarantees full traceability and conformance to the demanding quality and performance characteristics of the Hi-Lok system.

Technical Specifications

• Part Number: HL70-6
• Component Type: Hi-Lok Shear Frangible Hex Collar
• Material: A-286 Corrosion-Resistant Steel (CRES)
• Finish: Silver Plated
• Nominal Pin Diameter: For use with -6 (3/16 inch) Hi-Lok pins.
• Thread Specification: .1900-32 UNJF-3B
• Maximum Operating Temperature: Approx. 900°F (482°C)
• Installation Tool Requirement: Hi-Lok installation tool with a hex key to hold the pin stationary while the collar is tightened.

Aircraft Compatibility

Hi-Lok fastening systems, including the HL70-6 collar, are used extensively in the assembly of modern aircraft where high strength, low weight, and high temperatures are factors. They are found across the Textron Aviation product line.

• Common Aircraft Platforms:
  • Textron Aviation (Cessna & Beechcraft): Citation series business jets, King Air series, and other high-performance platforms.
  • • Textron Aviation Aircraft compatability:
    • • 1900 Airliner
      • 1900C Airliner
      • 1900D Airliner
      • Baron Series B55, E55, 58 or G58
      • Bonanza 36
      • Bonanza F33, G33, F33A or F33C
      • Caravan or Grand Caravan EX
      • Citation CJ1 or CJ1+
      • Citation CJ2 or CJ2+
      • Citation CJ3 or CJ3+
      • Citation CJ4
      • Citation III, VI or VII
      • Citation Latitude
      • Citation Longitude
      • Citation M2
      • Citation Mustang
      • Citation Sovereign or Sovereign+
      • Citation V, Ultra, Encore or Encore+
      • Citation X
      • Citation X+
      • Citation XLS, XLS+ or XLS Gen2
      • King Air 350 or 350C FM-1 to FM-35
      • Premier Model 390
      • SkyCourier
      • Stationair
    • Bombardier Aircraft compatability:
    • • Challenger 600
      • Challenger 601
      • Challenger 601-3A/3R
      • Challenger 604
      • Challenger 605
      • Challenger 650
      • Learjet 24
      • Learjet 25
      • Learjet 28
      • Learjet 29
      • Learjet 31
      • Learjet 35
      • Learjet 36
      • Learjet 55
      • Learjet 60 / 60XR
  • Universally used by other major airframe manufacturers like Boeing and Airbus.
• Common Applications:
  • Joining wing skins, spars, and ribs.
  • Assembling fuselage frames and bulkheads, particularly in firewall-forward sections.
  • Attaching primary structural brackets and fittings in high-temperature zones.

Applications

The HL70-6 collar is the specified component for creating permanent, high-strength structural joints:

• Fatigue-Critical Structures: The consistent preload achieved with the Hi-Lok system is essential for maximizing the fatigue life of a structural joint.
• High-Temperature Joints: Its primary application is in bolted joints that are exposed to significant heat, where it maintains its locking ability and strength.

Why Choose HL70-6?

The strength and reliability of an aircraft's structure is dependent on the integrity of its fastened joints. The Hi-Lok system, featuring the HL70-6 collar, provides a scientifically controlled method for achieving the correct clamp load, which is the most critical factor in a joint's performance. Using a genuine, traceable HL70-6 ensures you are installing a component with the certified material strength and precise engineering required to guarantee a safe, airworthy, and long-lasting structural connection, especially in high-temperature environments.

Order Your HL70-6 Hi-Lok Collars Now

Build and repair your aircraft structure with the precision and reliability of the Hi-Lok fastening system. Visit Airparts.aero to order your genuine HL70-6 collars today.

The Hi-Lok fastening system, which includes the HL70-6 collar, is a direct evolution of the traditional nut and bolt. It combines the benefits of a bolt and a rivet into one system. During installation, a special tool with a concentric sleeve holds the collar while an internal hex key passes through it to engage and hold the Hi-Lok pin stationary. As the tool tightens the collar, it stretches the pin, creating a high-preload clamping force on the structural members. When the preload reaches the designed value, the torque required to continue tightening exceeds the shear strength of the collar's thin-walled hex driver. This hex shears off cleanly, providing a visual indication of a completed installation and leaving behind a compact, permanent, and perfectly torqued collar.

Note: This is a flight-critical structural component. It must only be installed on the corresponding Hi-Lok pin of the correct diameter and grip length. Installation requires specialized Hi-Lok tooling. The sheared-off hex portion of the collar is discarded. These collars are not reusable.