Howmet Fastening Systems lightweight HUCKCOMP^® lockbolt fastener is a high-strength, lightweight aerospace fastener intended for use in composite material applications. The HUCKCOMP^® lockbolt fastener can help reduce aircraft weight due to its all-titanium construction, and it improves fastener installation time compared to threaded fasteners.

The HUCKCOMP^® fastener has design features similar to those of the LGP^® fastener. This fastening system has a large bearing area provided by a large pin head and a flanged titanium collar. The collar provides a high clamp load distributed over a wider area, keeping materials safe and undamaged. The large bearing area and high-clamp force give the HUCKCOMP^® fastener the ability to enhance joint integrity and fatigue performance.

Unlike threaded fasteners, lockbolts install rapidly and cannot vibrate loose. Their unique design assures predictable, consistent clamp force.

Design features

Collars for the HUCKCOMP^® fastener are made from CP titanium, which provides an all-titanium fastener installation that is compatible with graphite epoxy-type composite materials.

The HUCKCOMP^® lockbolt features lock grooves with a tapered root diameter and variable pitch. A larger volume of collar material flows into the locking grooves at the beginning of the installation sequence. This gives the fastener its greatest tensile strength where it is most crucial, resulting in a high residual clamp and high ultimate tensile. The 60° included angle of the locking groove has a 20° pressure flank angle, which serves as a platform for retaining the high clamp load generated during collar installation.

There are two types of HUCKCOMP® lockbolts: HUCKCOMP^® pull-type lockbolts and HUCKCOMP^® stump-type lockbolts.

Cost-effective features

Sloped surface installations:
Our HUCKCOMP^® fastener can be installed on sloped surfaces up to 5° on the collar side of the material being fastened. With this feature, heavy, costly, self-aligning washers and special nuts are not required. Inventory costs as well as structural weight is reduced. Fewer parts to handle translates into greater labor efficiency.

Extended grip range:
The HUCKCOMP^® fastener has a usable 3/32 in. grip range, which reduces inventory and installation errors that may occur when using conventional 1/16 in. grip range fasteners. The extended grip range makes the HUCKCOMP^® fastener more forgiving if the installer needs a fastener just over or just under the recommended grip. This often happens when fastening composite materials due to variations in material thickness and use of liquid shim materials.

Self-sealing:
The labor-intensive job of over-coating each fastener or the use of heavy, costly sealing nuts is eliminated with the HUCKCOMP^® fastener. Annular grooves on the pin form a series of separate barriers to prevent fuel seepage. Due to high clamp loads, fay surface sealant flow during installation ensures reliable sealing.

Vibration resistance:
Because the HUCKCOMP^® fastener uses annular instead of helical grooves and installations are made with a tension/tension action rather than a torque/tension action, there is no path for loosening in a vibrating environment.

Minimal rework:
Because the HUCKCOMP^® fastener’s pull-type installation, there is no surface damage often associated with torque-type fasteners.