What type of joint requires specific checks on faying surfaces?

The correct choice is based on the fact that slip-critical joints specifically rely on the friction between faying surfaces to resist movement. In these types of connections, the surfaces of the members being joined must be free from contaminants such as rust, oil, dirt, or paint that could reduce friction and lead to slippage.

To ensure effective load transfer and prevent failure, these surfaces must be tightly fitted together and appropriately tested to verify their condition before installation. This often involves inspecting the cleanliness of the faying surfaces and possibly performing some form of surface preparation or roughening.

In contrast, snug-tightened joints do not rely on friction alone but are designed to achieve a specific preload without the same level of surface preparation. Simple shear joints and bolted joints in tension also do not require the same rigorous checks on the faying surfaces since their structural integrity is derived from shear strength, tension capacity, or the clamping force of the bolts rather than the friction between the surfaces. Thus, the focus on faying surface preparation and condition is uniquely critical for slip-critical joints to perform their intended function safely and effectively.