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Maintenance Interval Hours Calculator

Work out maintenance interval hours instantly with clear inputs, formula shown and shareable results.

About Maintenance Interval Hours Calculator

Time-based maintenance tracking is straightforward arithmetic, but the useful output is the date the inspection falls due, which needs the average daily utilisation. Converting remaining hours into remaining days is what lets a scheduler place the check without grounding the aircraft mid-rotation.

Formula

Maintenance due

Remaining = interval - hours since last; days = remaining / average daily use

Worked example

With the default values below, Maintenance Interval Hours Calculator returns Hours remaining of 28.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Inspection interval
100 h
Hours since last inspection
72 h
Average daily use
2.5 h/day

Results

Hours remaining
28.00 h
Days until due
11.20 days
Interval consumed
72.0% %
Total hours at which it falls due
100.00 h

Step by step

  1. 1Values used
  2. 2Maintenance due
  3. 3Hours remaining= 28.00 h
  4. 4Days until due= 11.20 days
  5. 5Interval consumed= 72.0 %
  6. 6Total hours at which it falls due= 100.00 h

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Are calendar limits separate?

Yes. Many inspections have both an hours limit and a calendar limit, and whichever arrives first governs.

What about cycles?

Landing gear, pressure vessels and engine components are often limited by cycles rather than hours, so short-sector operators reach those limits sooner.

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