Fuselage stations (FS) define fore-aft locations on an airplane. All measurements begin at fuselage station 0.00, a reference datum placed near the nose and extending aft along the aircraft centerline. A station line is the vertical plane perpendicular to that centerline at each numbered inch, creating the longitudinal grid used to position bulkheads, doors, and equipment.
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What are fuselage stations?
Fuselage stations (FS) are used to define the location fore and aft on an airplane, and fuselage station 0 is generally located near the nose. Fuselage stations (FS) are the most commonly used of the references, which are planes cutting through the fuselage at right angles and are numbered along the longitudinal axis labeled as "stations."
A fuselage station is an inch-spaced coordinate that labels the longitudinal axis as stations. The reference point, called datum, is a permanent mark made ahead of the nose. The Boeing 737 NG series fixes this point 130.0 inches (330.2 cm) forward of the airplane nose. From that datum, measurements extend aft along the centerline of the aircraft, so FS 732 means 732 inches (1859.28 cm) aft of the reference. Each station line is a vertical plane perpendicular to the center line of the airplane, dividing the fuselage into body stations whose abbreviation is BS.
What is a fuselage station number?
A fuselage station number is a coordinate system for locating parts on an aircraft, where FS stands for Fuselage Station. Stations are vertical planes cutting through the fuselage at right angles, perpendicular to the center line of the airplane. Station line numbers increase from the nose to the back of the aircraft, and the number of a station indicates how many inches it is from station 0.
Longitudinal locations in an aircraft fuselage are identified with fuselage station numbers, abbreviated FSs. FSs are numerical reference points measured in inches from the reference datum, and the Aircraft Numbering System is the number of a station that tells how many inches it is from station 0. Station numbers are given in inches forward (negative) or aft (positive) of the zero datum.
The origin is ahead of the nose. When it is as such, the first measurable point on the fuselage is still station 0, and every successive station line is spaced one inch aft. Because FS is measured in inches from the reference datum, a part whose station number reads 300 is exactly 300 inches (762 cm) aft of the reference plane. Thus, the higher the fuselage station number, the farther aft the structural slice is located, giving technicians, engineers, and load planners a single, coherent scale that runs the entire length of the fuselage.
What is the horizontal fuselage datum?
The horizontal fuselage datum is a reference point called datum. The datum is an imaginary horizontal plane which serves as a reference for measured distances. Because fuselage stations are horizontal distances, their numbering begins at a defined vertical zero plane. This plane is the horizontal fuselage datum, an imaginary vertical reference surface established by the manufacturer. All fore-and-aft measurements - whether to a bulkhead, a seat row, or the center of gravity - are taken from this datum, making it the baseline for every longitudinal station on the aircraft.
What is another name for fuselage station zero?
Another name for fuselage station zero is the reference datum. The datum is identified as station zero. Station zero is the origin for all longitudinal measurements.
What are fuselage waterline and buttline coordinates?
Fuselage waterline coordinates are vertical axes labeled as "waterlines" (WL), and buttline coordinates are transverse axes labeled as "buttocks lines" (or butt lines, BL). The base line of the aircraft is designated as waterline 0 (zero), and stations are coordinates for where different parts are on an aircraft.
Positions along the y axis are buttline positions. BL 0 bisects the fuselage longitudinally and measures left and right of the structure’s centerline with negative values indicating left of centerline and positive values indicating right of centerline. The transverse axis is labeled as butt lines and is used for determining lateral placement of wing attachment points, landing gear assemblies, and horizontal stabilizers. Values are measured in decimal inches. They start from zero at the centerline and values stop and restart along the fuselage, with Right Butt Line 15.00 being twenty-five inches from Left Butt Line 10.00.
Positions along the z-axis are waterline positions. The baseline is designated as waterline 0 and is generally found near the ground or aligned with the fuselage base or cabin floor. Waterlines refer to horizontal planes parallel to the passenger floor and are measured in decimal inches, increasing upward; WL 100 is at the center of the fuselage. These waterlines establish the height of structural components including bulkheads, stringers, and floor beams. The system derives from the shipbuilding lofting process and, together with stations and butt lines, dictates where things are installed exactly within the airframe.
