Lesson 9: Aircraft Station Numbering System

What are the different station numbering system used in aircraft

An Aircraft Station Numbering or Fuselage stations (FS) are numbered in inches from a reference or zero point known as the reference datum.

Aircraft Numbering System is the number of a station tells how many inches it is from station 0. The reference point is called the datum.

 

Aircraft Station Numbering System


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These systems are used to locate specific wing frames, fuselage bulkheads, or any other structural member of an aircraft. Several types of systems are used. Listed below are the numbering systems.

Key points:

Airframe reference data, reference datum line, aircraft body, fuselage station numbers, body water lines, body buttock lines, buttock line, wings station numbers, panel numbering, locating access panels, Cartesian coordinates, reference datum line


Click here for the previous lessons, to learn about: Principle of Airframe; Principles of Aerodynamics; Airfoil Characteristics; Primary Flight Control Surfaces; Description and Operation of Helicopter; Miscellaneous Components of an Aircraft…


Reference Datum Line

aircraft reference datum line


This is an imaginary vertical plane located at or near the nose of the aircraft. It is from this line that all horizontal distances are measured.

Note: Station numbering are used on large aircraft like transports or tankers:

AIRCRAFT BODY (FUSELAGE) STATION NUMBERS,

We must have a starting point when using station numbers. The reference datum line is the starting point. The reference datum line is near the nose of the aircraft. The aircraft stations are numbered in inches fore or aft of this line. Most aircraft components can be located by a station number that specifies the number of inches the component is located from the reference datum line, as shown in Figure 1-44. If the component is on the wing the wing station number shows the number of inches to the right or left of the aircraft centerline that the component is located.

 

Fuselage Station Numbers and Water Line Numbers

Figure 1-44, Fuselage Station Numbers and Water Line Numbers

BODY WATER LINES,

 The reference for water lines is at some point below the fuselage and is called 0 water line. Horizontal, parallel lines are then drawn and numbered. The numbers tell how many inches the lines are from 0 water line.

BODY BUTTOCK LINES (BUTTOCK LINE),

The body buttock line is a vertical line is drawn through the center of the fuselage. This line is called 0 (zero) body buttock line. As illustrated in Figure 1-45, it divides the fuselage station in half. A series of body buttock lines is then drawn parallel to the 0 line. They are numbered in the same way as fuselage stations. A negative number indicates those on the left of the centerline and a positive number indicates those on the right of the centerline.

Thus, for components in the main fuselage of the aircraft, these three numbers are sufficient to exactly define its position in the aircraft. However, if the component is found along or inside one of the wings, another number is required. This number is called the wing station (WS) number and is measured along either wing, beginning at the centerline of the aircraft and moving outward along the wing. This is also measured in inches.

 

Body Buttock Lines

Figure 1-45, Body Buttock Lines

WINGS STATION NUMBERS,

 The wings, nacelle, and tail surfaces are also divided into stations as shown in figure 1-46. Body buttock lines measure horizontal distances at these stations and vertical distances are measured by water lines.


Wing Station Numbers


 Figure 1-46, Wing Station Numbers

Panel Numbering

LOCATING ACCESS PANELS,

The best way to find aircraft components is to first find the access panel or door that will provide access to the different components. The access panels or doors are numbered differently on different aircraft. On some aircraft, the access panels on the left have odd numbers and those on the right side have even numbers. On other aircraft, the access panels on the right side have an ”R” associated with the number, while the numbers on the left side have an ”L.” There are other numbering systems, so you must refer to the –2 TO for the specific aircraft to find a list of access panels and doors.

Each access door is numbered and the numbers are listed to show the component to be found behind each panel or door. See Figure 1-47. Normally, the –2 TO will show which panel you must open or remove to do a task. Then all you should do is refer to the –2 TO to find out where the panel is located. Not all the components can be found by locating the access door. Some aircraft parts and components must be found by the use of aircraft station numbers

aircraft LOCATING ACCESS PANELS


 Figure 1-47, Aircraft Panel 

CARTESIAN COORDINATES,

 Cartesian coordinates are used to pinpoint the location and placement of each part on the airplane, from attachments to major assemblies, using the X, Y, and Z-axis for planes of reference. See Figure 1-48.


aircraft Cartesian coordinates


Figure 1-48, Cartesian coordinates