Unlike pressurized airplanes and jets that have a finite useful life, helicopters can have unlimited life. The major assemblies that make up a helicopter are the main determining factor when valuing the aircraft. For this reason, the Blue Book breaks down resale values by average weighted component use. Weighted average is defined as an average resulting from the multiplication of each component by a factor reflecting its importance. The major drivetrain components of a helicopter have varying overhaul and retirement cost. More expensive parts hold a greater weight than lower cost components. HeliValue$ calculations for finding the average weighted use is proprietary to our appraisal programs. The columns (0%, 20%, 40%, 50%, 60%, 80%, 100%) are provided so subscribers can get a general idea of the spread of values based on component usage. If a specific value based on your helicopters actual component status and specific installed equipment is needed, we suggest a formal desktop appraisal performed by one of our ASA accredited appraisers. Alternatively, you may consider purchasing a HeliCalc® report. HeliCalc® requires knowledge of how to correctly read and analyze component status reports. Please see the FAQ section on HeliCalc® for more information.