|
A.G.S. Parts For Aircraft
Aircraft General Standard.
One of many ads in the components subsection on
the Website for A.G.S. parts and supplies.
In this article you'll learn a little more about some of these small but
crucially important items.
Introduction:
Aircraft general standard (A.G.S.) parts are small items such as bolts, nuts,
rivets, fork joints, taper pins, common to all types of aircraft. They are made
in a range of sizes, and, as similar parts are made of different materials, a
distinguishing system of identification is in use. Special parts made for
specific aircraft have no marking to indicate size or material, but are marked
with a part number.
Bolts And Screws:
B.S.F. or U.N. F. threads are used on all standard bolts of 1/4in. dia. and over
; No. 2, 4 and 6 B.A. or U.N.F. are used for smaller sizes. The bolt type is
indicated by the shape of the head and each type is made in various lengths and
diameters ; the dimensions of the head and the length of the thread are
standardised for each diameter of bolt.
Information such as material, thread diameter,
length of the plain unthreaded portion, whether the thread is left- or
right-hand and whether the bolt is corrosion resistant is marked on the carton
label and may be stamped on the bolt head. This information is abbreviated and
in the form of a part number consisting of two to five letters and figures which
are related to a size code.
Hexagon-headed Steel Bolts.
These bolts of 1/4 in. dia. and over are stamped with the part number, such as
14G; the number equals the length of the plain unthreaded portion of the shank
in tenths of an inch, that is 1·4 in. and the letter "G" indicates that the
thread diameter is 5/16 in. (see size code). Vee grooves cut into the head at
right-angles to the bolt axis indicates that the bolt is made of high tensile
steel. If the bolt is corrosion resistant, that is high tensile stainless steel,
the part number is prefixed by the letter " Z" (Z14G), Bolts with left-hand
threads have an
additional suffix letter "L" after the part number.
Close tolerance bolts, which are made of
high tensile steel, are marked with grooves cut in the head and have a raised
disc on the head. Coldheaded bolts are either marked with an embossed ring on
the head, or, if a UNF bolt, with a shallow depression in the centre of the head
, equal to the shank diameter. To indicate a Unified screw thread, a symbol
consisting of two or three circles is marked on the part, carton label or
aircraft containing this type of thread . Unless otherwise stated, a replacement
bolt and nut must be of the same size, type and material as the original bolt
and nut.
Notes.
1. A washer face under a bolt head is not provided for identification
purposes, but is the result of using a particular machine in the manufacture of
the bolt.
2. Bolts and nuts may be either machined or cold formed but, irrespective
of the method of manufacture, bolts or nuts of identical material, type, thread
and size are interchangeable.
3. When in doubt as to the identification of new bolts and nuts,
reference should be made to the label on the carton in which the bolts or nuts
were contained.
4. The use of mild steel bolts in aircraft construction has been
discontinued, but a range of bolts in this material and in brass is available
for use in aircraft ancillary equipment.
Hexagon-headed Aluminium Alloy Bolts . .
All sizes of aluminium alloy bolts of older stock are marked with a letter "L"
embossed or stamped on the head to indicate the material. Bolts of 1/4 in. dia.
and over are also marked with the part number as described. In later
stocks two parallel lines replace the " L" to indicate the material. Where
colour marking is used for identification purposes all aluminium alloy bolts
have an anodic film dyed green.
Next Page >>>>> |