A number of issues contribute to the difficulty in presenting a clear figure for a make/model/year, such as lack of central reporting of aircraft sales for either tax or license requirements, the complexity of individual aircraft value calculations, the timing of sales (long timeframes from offer to closing during which time the market can go up or down substantially), multiple synchronous closings for jet aircraft in particular, international currency sales, and non-disclosure-of-price terms included in many transaction documents.
Appraisals usually include an onsite inspection and can be influenced by complex variables such as the year (manufactured year, delivery year, serial number sequence); time on airframe and engines (or until upcoming major inspection and maintenance events); damage (including where/how repaired); logbook and upgrades history; previous owners (number, type usage, and geographic location); maintenance programs (specially approved maintenance schedules and/or power by the hour engine insurance type plans); avionics; options; current mechanical, interior and exterior condition etc.
The Aircraft Bluebook Price Digest is a quarterly print publication by Informa (also available on CD-ROM) that was established in the 1950s.
It identifies and prices more than 3,000 used general aviation aircraft and helicopter make and model-years available in the United States.
[3] The Bluebook scale is an index published by the Price Digest that tabulates the condition of an aircraft.