LLP Remaining Life and Pro-Rata Value Calculator
A life-limited part must be retired when it reaches its approved cycle limit, regardless of condition. This calculator shows how much life is left, what that remaining life is worth on a pro-rata basis and how many months you have before the replacement has to be on the shelf.
Your numbers
Limit from the manufacturer's life-limits section or airworthiness limitation document.
Verified from traceable records, not an estimate.
Manufacturer catalogue price at the time of valuation.
Cycles you refuse to fly in order to avoid scheduling at the limit.
Average for the engine or module position.
Time to source, receive and document the replacement part.
Your results
Valuation here is a simple linear pro-rata of list price. Market and contract values apply discounts, and only traceable back-to-birth records support the cycle count.
Months to limit vs cycles flown per month
Sweeps Cycles flown per month from 40 to 400, holding your other inputs fixed.
LLP watch list from your records
Optional: we can discuss how to build a limit-watch report from your existing part and installation records.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter the approved cycle limit and the verified cycles since new, then the current list price. Add a planning buffer so you never schedule work at the exact limit, the average cycles flown per month and the lead time for a replacement. The tool returns remaining cycles, life used, the value of what is left and the latest month to place the order.
Method
Remaining life is limit minus used, floored at zero. The pro-rata value is list price times remaining over limit, which is the common basis for credit discussions on LLP trades and for lease return adjustments. The ordering window is the months to the buffered limit minus the replacement lead time.
- Remaining = limit - CSN
- Pro-rata value = list price x remaining / limit
- Months to limit = (remaining - buffer) / cycles per month
- Order by = months to limit - lead time
Worked example
A disk with a 20,000 cycle limit and 14,200 cycles used has 5,800 left. At 380,000 dollars list it carries about 110,200 dollars of pro-rata value. With a 300 cycle buffer and 160 cycles a month it reaches the planning limit in about 34 months, so with a six month lead time you must order within roughly 28 months. If utilization doubles, the order window collapses to about 11 months.
Common mistakes
Using hours where the limit is in cycles, trusting a cycle count that has gaps in back-to-birth traceability, and forgetting that a module can carry several parts with different limits are the main traps. Always plan against the most limiting part in the module, and keep the source documents with the figure.
Frequently Asked Questions
Is linear pro-rata the market value?
Not exactly. It is the reference basis used in many negotiations, but actual trades apply discounts to list price and may value near-limit parts at little more than scrap. Use it as the starting point, not the final number.
Why add a planning buffer?
Because removal, shop slot and part delivery can slip. Scheduling at exactly the limit leaves no margin, and an aircraft or engine that hits the limit must come off wing regardless of the schedule.
Does the limit ever change?
Limits can be revised by the manufacturer or authority in a revision to the limitations document. Always check the current revision and the applicable engine or part number configuration before relying on a figure.
What if the part has both a cycle and a calendar limit?
Run the calculator for the cycle limit and separately track the calendar limit. Whichever date arrives first governs, so keep both on the planning list.
Netray can set up a read-only agent over your ERP and records system that lists every LLP nearing its limit with the traceability documents behind each cycle count.
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