Most FAA documents are located in the Dynamic Regulatory System (DRS). The address of the main page shown at the right is https://drs.faa.gov. To access some content, you will need to create a free account by clicking the sign link in the green box at the upper right corner. The Help & Training link just under the green box will provide you with lots of help on how to use the system. I find searching using the document type/category search box in red on the left side most helpful.
For example: To find the Type Certificate Data Sheet for a Cessna 182 aircraft. Enter "type certificate" into the document type/category search box (red box) and click on "Type Certificate Data Sheets (TCDS)" link below it. This brings up the Type Certificate Data Sheets (TCDS) search filter. Then enter "182" under model (green box). Finally click on "Submit" at the lower right corner (orange box). Then scroll down to display "TCDS Number : 3A13". Click on that (brown box) to bring up the type certificate for the C182 series.
BTW: Entering something in any box will lock out invalid entries in other boxes. For example: you may think that a 182 is a Cessna so you enter "Cessna" in the "TC Holder" box (purple box). You will then not be able to enter "182" in the model box because Cessna is not the TC Holder for 182 models, Textron now is the holder of the TC. You could enter "Cessna Aircraft Company" (not "Cessna Aircraft Co") into "Former TC holders" to be able to enter "182" into model. When using filters in the DRS, less is often more.
FAA Aircraft Weight and Balance Handbook
The objective of this handbook is twofold: to provide the airframe and
powerplant mechanic (A&P) with the method of determining the empty weight and empty weight center of gravity (EWCG)
of an aircraft and to furnish the flight crew with information on loading and operating the aircraft to ensure its weight is
within the allowable limit and the center of gravity (CG) is within the allowable range.
AC 43.13-1B - Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair
AC 43.13-2B - Acceptable Methods, Techniques, and Practices - Aircraft Alterations
These two books are called "the mechanic's bibles."
These advisory circulars contain methods, techniques, and practices for the inspection, repair and modification of non-pressurized areas of 12,500 lbs gross weight or less. Book 1B generally pertains to minor repairs while book 2b covers major repairs and alterations.
