Aviation Maintenance Terms beginning with M
Magnetic particle inspection
A method of detecting invisible cracks and other defects in ferromagnetic materials such as iron and steel. The inspection process consists of magnetizing the part and then applying ferromagnetic particles to the surface area to be inspected.
Maintenance
This includes inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.
Major alteration
An alteration not listed in the aircraft, aircraft engine, or propeller specifications: (1) that might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or (2) that is not done according to accepted practices or cannot be done by elementary operations.
Major repairs
A repair that (1) if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness, or (2) is not done according to accepted practices, or cannot be done by elementary operations.
Malfunction or Defect Report
A report (FAA Form 8010-4) providing the FAA and industry with a very essential service record of mechanical difficulties encountered in aircraft operations. Such reports contribute to the correction of conditions or situations which otherwise will continue to prove costly and/or adversely affect the airworthiness of aircraft.
Manufacturer’s maintenance manual
A manual provided by an aircraft manufacturer that outlines the methods, techniques, and practices prescribed for each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance.
Mass
A measure of the quantity of matter in an object.
Matter
Any substance that has mass and takes up space.
Maximum landing weight
The heaviest weight an aircraft can have when it lands. For large wide body commercial airplanes, it can be 100,000 pounds less than maximum takeoff weight, or even more.
Maximum ramp weight
The heaviest weight to which an aircraft can be loaded while it is sitting on the ground, sometimes referred to as the maximum taxi weight.
Maximum takeoff weight
The heaviest weight an aircraft can have when it starts the takeoff roll. The difference between this weight and the maximum ramp weight would equal the weight of the fuel that would be consumed prior to takeoff.
Maximum weight
The maximum authorized weight of the aircraft and its contents, and is indicated in the Aircraft Specifications or Type Certificate Data Sheet.
Maximum zero fuel weight
The heaviest weight an aircraft can be loaded to without having any usable fuel in the fuel tanks. Any weight loaded above this value must be in the form of fuel.
Mean aerodynamic chord (MAC)
The average distance from the leading edge to the trailing edge of the wing.
Mechanical advantage
A ratio of the resistance force to the effort force.
Mechanical energy
This includes all methods of producing increased motion of molecules such as friction, impact of bodies, or compression of gases.
METO horsepower
The maximum power allowed to be continuously produced by an engine. Takeoff power is usually limited to a given amount of time, such as 1 minute or 5 minutes.
Mixed number
A combination of a whole number and a fraction. For example, 53⁄8 is a mixed number.
Molecule
The smallest particle of an element or compound that retains the chemical properties of the element or compound.
Moment
In determining weight and balance, the moment is the product of a weight multiplied by its arm.
MS flareless fittings
Designed primarily for highpressure (3,000 psi) hydraulic systems that may be subjected to severe vibration or fluctuating pressure. Using this type of fitting eliminates all tube flaring, yet provides a safe and strong, dependable tube connection. The fitting consists of three parts: a body, a sleeve, and a nut.
Multiplication
The process of repeated addition
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