Aviation Maintenance Terms beginning with J

Jackscrew

A hardened steel rod with strong threads cut into it. A jackscrew is rotated by hand or with a motor to apply a force or to lift an object.

---

Jet fuel

Fuel designed and produced to be used in aircraft gas turbine engines.

---

Jet propulsion

A method of propulsion by accelerating a relatively small mass of air through a large change in velocity.

---

Jet pump

A special venturi in a line carrying air from certain areas in an aircraft that need an augmented flow of air through them. High-velocity compressor bleed air is blown into the throat of a venturi where it produces a low pressure that pulls air from the area to which it is connected. Jet pumps are often used in the lines that pull air through galleys and toilet areas.

---

Jeweler’s file

A small, fine-cut, metalworking file used by jewelry manufacturers.

---

Joggle

A small offset near the edge of a piece of sheet metal. It allows one sheet of metal to overlap another sheet while maintaining a flush surface.

---

Jointer

A woodworking power tool used to smooth edges of a piece of wood.

---

Joule

A measure of energy. In terms of electrical energy, one joule is equal to one watt-second.

---

Joule

The amount of work done by a force of one newton when it acts through a distance of one meter

---

Journal (bearing)

A hardened and polished surface on a rotating shaft that rides in a plain bearing.

---