A/C Body Station Designations

Date:         03 Nov 97 02:18:53 
From:         stevec00@juno.com (Joel S Cole)
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>Could someone please inform me as to where the reference point
>is that body stations are measured from on commercial aircraft?
>Is it the forward pressure bulkhead?  Is it the mounting
>structure for the weather radar?  Please let me know.

>And a final question.  How does Airbus designate the body
>stations?  Please let me know.

	The Origin of the axis for the Fuselage Stations(FS) is generally
located at some point forward of the aircraft.  I assume this is done to
allow for any changes in the fuselage lenght due to design or later
post-production modifications, as I will illustrate below.

	For the Airbus A300, the FS origin is 638 cm forward of the
aircraft nose.  This equates to a whopping 20feet-11.2inches !  This
means the radome bulkhead is at FS 766 cm.  I tried to find the exact
drawing reference to give you, but did not have time.  My reference is
the A300 Structural Repair Manual.

	An aircraft such as the Bell AH-1T helicopter gunship has its
origin 12.36 inches ahead of the nose, which puts the mast eaxactly at FS
200 and, you might say, makes the forward arc of the rotor blade tip at
FS= -88.  For some reason they liked the mast center to be at FS 200.

	As stated above, when an aircraft undergoes a mod to stretch the
fuselage, this makes life interesting.  The B727-200, which has a FS
origin at 130 inches ahead of the nose, has designated stations as FS- A,
B, C, D for the inserted fuselage sections.  The DC10 has nose beginning
at FS 239.  Then when the MD11 came along, the drawings adjusts the
forward fuselage by -100 and the aft fuselage by +123.  Therefore, a
forward fuselage station may be referenced by FS 455/555.  They wanted to
keep the DC10 station ID so all drawings would not have to changed.

	Hope this helps.  There is no set rule that I know about.

                                          STeve Cole~