CFS Blind Fasteners & Rivets 3

Question 1

A lockbolt (e.g., Huck C6L or Hi-Lok) is distinguished from a break-mandrel blind rivet primarily because:

Accepted Answer

A lockbolt uses a swaged collar on the pin rather than a collapsing rivet body

Answer

Lockbolts consist of a pin (bolt) and a collar that is swaged into annular locking grooves by the installation tool, providing high clamp force and vibration resistance distinct from standard blind rivets.

Question 2

In aerospace applications, why are blind fasteners often preferred over solid rivets for repair work even when both sides of the structure are accessible?

Accepted Answer

Blind fasteners eliminate the need for a bucking bar, simplifying one-person repair in confined areas

Answer

Even when both sides are accessible, using blind fasteners removes the need for a bucking bar operator, enabling faster one-person installation in confined or hard-to-reach airframe structures.

Question 3

Which of the following best describes the 'clamp force' (clamping load) developed by a blind rivet?

Accepted Answer

The compressive preload applied to the joint members as the blind side bulge forms and the mandrel breaks

Answer

Clamp force is the compressive preload clamped onto the joint stack as the rivet body upsets on the blind side and the mandrel fractures, drawing the materials together.

Question 4

A self-plugging blind rivet retains the mandrel in the set rivet body. What is the primary reason for this design feature?

Accepted Answer

To seal the rivet body and increase shear and tensile strength by adding mandrel load transfer

Answer

Retaining the mandrel inside the set body seals out moisture and adds load-carrying cross-section, boosting both tensile and shear performance compared to open-end rivets where the mandrel is lost.

Question 5

What is the purpose of the countersunk (flush) head style available in blind rivets, such as those meeting NAS 1738?

Accepted Answer

To create an aerodynamically smooth surface flush with the parent material, reducing drag in aerospace assemblies

Answer

Countersunk head blind rivets sit flush within a countersunk hole, providing a smooth outer surface essential for aerodynamic fairings, skin panels, and any application requiring a flush finish.

(CFS) Certified Fastener Specialist Practice Test

(CFS) Certified Fastener Specialist Practice Test

CFS Blind Fasteners & Rivets 3