This appraisal is typically requested by the aircraft owner to determine the aircraft's current market value. This is often required for a possible sale or dissolution of a partnership share.
This appraisal involves a more complete inspection of the aircraft and its logbooks. This is usually required by a lender before issuing a loan on the aircraft.
I do not belong to or endorse the two companies who offer a correspondence course to become an aircraft appraiser. There is no company or association which has any kind of certification authority. These correspondence courses basically teach one how to interpret the aircraft bluebook to determine its value.
I have witnessed many appraisals and only felt one person knew what he was doing. One appraiser didn't know the difference between a Bonanza and a Baron. None took off an inspection panel, only one opened the engine cowling, and only one studied the logbooks.
"Bluebook Appraisers" don't take into consideration the following: