Aeronautical Terms beginning with M
MAC
Mean Aerodynamic Chord.
Magnetic Compass
A device for determining direction measured from magnetic north.
Magneto
A self-contained, engine-driven unit that supplies electrical current to the spark plugs; completely independent of the airplane’s electrical system. Normally there are two magnetos per engine.
Magnus effect
Lifting force produced when a rotating cylinder produces a pressure differential. This is the same effect that makes a baseball curve or a golf ball slice.
Main Gear
The wheels of an aircraft’s landing gear that supports the major part of the aircraft’s weight.
Maintenance
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 repair
A repair:
(1) That, if improperly done, 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.
Maneuverability
Ability of an aircraft to change directions along a flightpath and withstand the stresses imposed upon it.
Maneuvering Speed (Va)
The maximum speed where full, abrupt control movement can be used without overstressing the airframe.
Manifold absolute pressure
The absolute pressure of the fuel/air mixture within the intake manifold, usually indicated in inches of mercury.
Manifold Pressure (MP)
The absolute pressure of the fuel/air mixture within the intake manifold, usually indicated in inches of mercury.
Maximum Allowable Takeoff Power
The maximum power an engine is allowed to develop for a limited period of time; usually about one minute.
Maximum Landing Weight
The greatest weight that an airplane normally is allowed to have at landing.
Maximum Ramp Weight
The total weight of a loaded aircraft, including all fuel. It is greater than the takeoff weight due to the fuel that will be burned during the taxi and runup operations. Ramp weight may also be referred to as taxi weight.
Maximum Takeoff Weight
(GAMA) Maximum weight approved for the start of the takeoff run.
Maximum Weight
The maximum authorized weight of the aircraft and all of its equipment as specified in the Type Certificate Data Sheets (TCDS) for the aircraft.
Maximum Zero Fuel Weight
The maximum authorized weight of an aircraft without fuel. This is the total weight for a particular flight less the fuel. It includes the aircraft and everything that will be carried on the flight except the weight of the fuel.
Mean aerodynamic chord (MAC)
The average distance from the leading edge to the trailing edge of the wing.
METO Horsepower (maximum except takeoff)
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.
Minimum Controllable Airspeed
An airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in an immediate stall.
Minimum drag
The point on the total drag curve where the lift-to-drag ratio is the greatest. At this speed, total drag is minimized.
Minimum Fuel
The amount of fuel necessary for one- half hour of operation at the rated maximum-continuous power setting of the engine, which, for weight and balance purposes, is 1/12 gallon per maximum-except-takeoff (METO) horse-power. It is the maximum amount of fuel that could be used in weight and balance computations when low fuel might adversely affect the most critical balance conditions. To determine the weight of the minimum fuel in pounds, divide the METO horsepower by two.
Minor alteration
An alteration other than a major alteration.
Minor repair
A repair other than a major repair.
Mixture
The ratio of fuel to air entering the engine’s cylinders.
Moment
The product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches (lb-in). Total moment is the weight of the airplane multiplied by the distance between the datum and the CG.
Moment Arm
The distance from a datum to the applied force.
Moment Index
The moment (weight times arm) divided by a reduction factor such as 100 or 1,000 to make the number smaller and reduce the chance of mathematical errors in computing the center of gravity.
Moment Limits vs Weight Envelope
An enclosed area on a graph of three parameters. The diagonal line representing the moment/100 crosses the horizontal line representing the weight at the vertical line representing the CG location in inches aft of the datum. When the lines cross inside the envelope, the aircraft is loaded within its weight and CG limits.
Monocoque
A shell-like fuselage design in which the stressed outer skin is used to support the majority of imposed stresses. Monocoque fuselage design may include bulkheads but not stringers.
Monoplanes
Airplanes with a single set of wings.
Movable Slat
A movable auxiliary airfoil on the leading edge of a wing. It is closed in normal flight but extends at high angles of attack. This allows air to continue flowing over the top of the wing and delays airflow separation.
Restrict the list to specific categories by clicking on the menubar at the top of the screen.