Line stretch. Occurs during deployment, after the lines are fully extended. Follows snatch force and line extension.

Line-over. A type of deployment malfunction that occurs when one or more suspension lines pass over the top of the canopy during deployment preventing complete, normal inflation. Not to be confused with “partial inversions.”

Locking cone. A cone shaped metal device used in conjunction with end tabs and ripcord pins to hold the container flaps closed.

Locking pins. Straight or curved metal pins used with a throwout or pull-out pilot chute for securing the container closed.

Locking ripcord pin. A small metal prong, slightly smaller in diameter than the ripcord cable and fastened to it by means of a swage fitting or serving and solder. One pin is attached to the end of the cable and the others (when two or more are used) are set at intervals on the cable. The spacing of the pins is dependant on the distance between the cones on the container flap. The locking pins pass through the locking cones of the flaps and thus serve to lock the container until such time as the pins are withdrawn.

Lockstitch. Type of stitching used in manufacturing parachutes. This type of stitch is formed by two threads. A loop of the thread is passed through the material where it is entered by the supply of the other thread. The loop of the first thread is drawn into the material to the extent that the loop or lock is approximately halfway between the two surfaces of the material. Also known as a type 301 stitch.

Loft. A facility for the repair and maintenance of parachutes.

Logbook. A format for complying with 14 CFR part 65, subsection 65.131(a) in regards to recording the work done by the rigger on parachutes.

Machine head. The entire metal housing that supports the moving parts and bearings of the machine.

Main parachute. A parachute assembly, excluding the harness, that is used in conjunction with a reserve parachute assembly as the primary assembly for a premeditated jump.

Main seam. That which joins two adjacent gores in a canopy; also known as a radial seam.

Maintenance. Inspection, overhaul, repair, preservation, and replacement of parts but excludes preventative maintenance.

Major repair. A repair that, if improperly done, might appreciably affect weight, balance, structure strength, performance, powerplant operation, flight characteristics or other qualities affecting airworthiness; or that is not according to accepted practices or cannot be done by elementary operations.

Malfunction. The complete or partial failure of the parachute canopy to effect proper opening and descent. Some malfunctions are canopy damage, twisted suspension lines, inversion or semi-inversion of the canopy, a line over, etc.

Malfunction or Defect Report, FAA Form 8330-2. A form used to report serious defects or other recurring unairworthy conditions of parachutes or aircraft.

Marquisette. Netting.

Mass. The quantity of matter in an object.

Master Parachute Rigger. An individual certified by the FAA to pack, maintain, and alter parachutes. The highest classification of parachute rigger.

Maximum operating weight. The total weight of the parachutist and all equipment that exits the aircraft with the jumper.