Plain English Meaning

A small pump on the engine that sucks air through certain flight instruments to make them work. It is called 'dry' because it doesn't need oil to lubricate its inner parts.

Full Definition

An engine-driven pump that uses self-lubricating carbon vanes to move air without internal oil, creating the suction (vacuum) needed to drive gyroscopic flight instruments such as the attitude indicator and heading indicator.

Context Anchor

Seen in aircraft systems, maintenance records, and accident reports involving vacuum-powered flight instruments.

Derivation

Dry' refers to the absence of oil lubrication inside the pump, distinguishing it from earlier 'wet' pumps that used . '' describes its function: it removes air to create a (a vacuum) that the .