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The quantity of the full oil supply and its arm are given in
such terms as:
“26 qt (+88)”
Data Pertinent to All Models
Datum
The location of the datum may be described, for example, as:
“Front face of firewall”
—or,
“78.4" forward of wing leading edge (straight wing only).
78.4" forward of inboard intersection of straight and tapered
sections (semi-tapered wings).”
Leveling Means
A typical method is:
“Upper door sill.”
This means that a spirit level is held against the upper door
sill and the aircraft is level when the bubble is centered.
Other methods require a spirit level to be placed across
leveling screws or leveling lugs in the primary aircraft
structure or dropping a plumb line between specified
leveling points.
TCDS are issued for aircraft that have been certificated since
January 1, 1958, when the FAA came into being. For aircraft
certificated before this date, basically the same data is
included in Aircraft, Engine, or Propeller Specifications that
were issued by the Civil Aeronautics Administration.
The book, Aircraft Listings, Volume VI of the Type Certificate
Data Sheets Specifications and Listings, includes weight and
balance information on aircraft of which there are fewer than
50 listed as being certificated.
Manufacturer-Furnished Information
When an aircraft is initially certificated, its empty weight and
EWCG are determined and recorded in the weight and
balance record such as the one in Figure 2-21. Notice in this
figure that the moment is expressed as “Moment (lb-in/
1000).” This is a moment index which means that the
moment, a very large number, has been divided by 1,000 to
make it more manageable. Chapter 4 discusses moment
indexes in more detail.
Figure 2-21. Typical weight and balance data for a 14 CFR, Part 23 airplane.
2–13
Dealing with Large Moments
Moments are the product of the arm in inches and the weight in
pounds, and for large aircraft this produces very large numbers. To
reduce the likelihood of mathematical errors, the manufacturers often
divide these large numbers by a reduction factor of 100 or 1,000 to
get a moment index which is easier to handle. To change a moment
index to a moment, just multiply it by the reduction factor.
Equipment list: A list of items
approved by the FAA for installation
in a particular aircraft. The list
includes the name, part number,
weight, and arm of the component.
Installation of an item in the
equipment list is considered to be a
minor alteration.
An equipment list is furnished with the aircraft which specifies
all the required equipment, and all equipment approved
for installation in the aircraft. The weight and arm of each
item is included on the list, and all equipment installed when
the aircraft left the factory is checked.
When an AMT adds or removes any item on the equipment
list, he or she must change the weight and balance record to
indicate the new empty weight and EWCG, and the
equipment list is revised to show which equipment is actually
installed. Figure 2-22 is an excerpt from a comprehensive
equipment list which includes all of the items of equipment
approved for this particular model of aircraft. The POH for
each individual aircraft includes an aircraft specific equipment
list of the items from this master list. When any item is
added to or removed from the aircraft, its weight and arm are
determined in the equipment list and used to update the
weight and balance record.
The POH/AFM also contains CG moment envelopes and
loading graphs. Examples of the use of these handy graphs
are given in Chapter 4.
Figure 2-22. Excerpt from a typical comprehensive equipment list (continued on next page).
2–14
Figure 2-22. Excerpt from a typical comprehensive equipment list (continued).
3–1
Chapter 3
Weighing the Aircraft and
Determining the Empty-Weight
Center of Gravity
Chapter 2 explained the theory of weight and balance and
gave examples of the way the center of gravity could be
found for a board loaded with several weights. In this
chapter, the practical aspects of weighing an airplane and
locating its center of gravity are discussed. Formulas are
introduced that allow the CG location to be measured in
inches from various datum locations and in percentage of
the mean aerodynamic chord.
Requirements
Weight and balance is of such vital importance that each AMT
maintaining an aircraft must be fully aware of his or her
responsibility to provide the pilot with current and accurate
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