Definition
A unit of torque equal to the twisting force produced by one pound of force applied at the end of a lever one inch long. Pound-inches measure how tightly a fastener has been turned, not how hard something is being pushed or pulled.
Plain English
A way of measuring tightening force. One pound-inch is the force you'd feel if you hung a one-pound weight on the end of a wrench one inch from the bolt.
Context Anchor
Seen in aircraft weight-and-balance calculations and in some maintenance torque specifications.
Derivation
The name describes the measurement directly: pounds of force multiplied by inches of lever length. It's the small-fastener cousin of pound-feet (foot-pounds), used where the required torque is too low to measure accurately in the larger unit.
Why Pilots Care
Ensures fasteners are tightened correctly to maintain structural integrity and prevent loosening or damage in flight.
Intuition Check
Do not read pound-inches as pounds per inch, or as pounds and inches listed separately. It means pounds multiplied by inches.
Example Sentence 1
The maintenance manual called for the spark plugs to be torqued to 360 pound-inches.
Example Sentence 2
The propeller installation procedure called for checking all bolts at the specified pound-inches value.