Measurement, Test & Control Equipment worked example

Returned Unit Diagnostic Time at 14% intermittent fault and nff allowance: a worked example

Suppose intermittent fault and nff allowance falls to 14%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate total labor hours needed to diagnose a batch of returned or failed units, including fault isolation, functional test, and root cause documentation. Plan repair depot capacity and technician workload.

The inputs for this scenario

  • Units awaiting diagnosis: 35 units (held at the documented default)
  • Average diagnostic time per unit: 90 min / unit (held at the documented default)
  • Intermittent fault and NFF allowance: 14 % (the input this scenario stresses; the baseline uses 20)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base diagnostic time = units awaiting diagnosis x average diagnostic time per unit.
  • Total diagnostic time (hours) works out to 0.44 hr at these inputs, and this is the headline figure for the scenario.
  • Base diagnostic time (hours) works out to 0.39 hr at these inputs.
  • Intermittent fault allowance (hours) works out to 14 % at these inputs.
  • Diagnostic rate (units/min) works out to 90 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where intermittent fault and nff allowance sits at 20% and the headline result is 0.47 hr, this scenario comes in 5% below the baseline at 0.44 hr.
  • It multiplies the number of units awaiting diagnosis by the average diagnostic time per unit, then adds an intermittent-fault and NFF allowance to give total diagnostic hours. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Total diagnostic time (hours): 0.44 hr (headline result)
  • Base diagnostic time (hours): 0.39 hr
  • Intermittent fault allowance (hours): 14 %
  • Diagnostic rate (units/min): 90 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Returned Unit Diagnostic Time calculator, set intermittent fault and nff allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.