ESN value sheet analysis: what an engine serial number tells you

What is on the sheet

• Identity: model, thrust rating, ESN, current status (on wing, stored, at a shop) and lease status.
• Time: TSN, CSN, time and cycles since the last shop visit.
• Life-limited parts: each LLP, its cycles used and remaining, and the limiting part that will force the next shop visit.
• Shop visit history: when, where, what workscope, with reports.
• Performance: the last EGT margin and the trend.
• Configuration: QEC or EBU status, modifications and service bulletins incorporated.
• Records: complete or with gaps, and which gaps.
• Open items: ADs due, repetitive inspections, findings from the last borescope.

How the lines move the value

LLP life remaining is the largest driver: the remaining life of each part has a value, and the part closest to its limit sets the date of the next expensive visit. Time to the next performance restoration — "green time" — is the second. EGT margin, records condition and configuration gaps move the number from there, and an open AD or a borescope finding beyond limits can take an engine from an asset to a project.

What the sheet is not

It is the technical basis for a valuation, not the valuation. An appraiser uses it; a buyer negotiates on it; a lender checks it. It should be built by someone who has seen the engine and the records, not only the spreadsheet.