Our Repair Turn Time Is Too Long
In most repair and overhaul shops a unit spends more time waiting than being worked: for a teardown slot, for parts, for an engineering call, for the test stand. Turn time is a WIP problem as much as a labor problem. At the same output, fewer work orders open means a shorter turn.
What Is Usually Going On
- Units are inducted as they arrive, so work orders pile up and each one waits longer.
- Parts are ordered after teardown, so the unit waits out the parts lead time.
- A shared test stand, bay or inspection step is the constraint and nobody manages its queue.
- Engineering dispositions and approvals sit in a queue nobody measures.
- Scope is unknown until teardown, and plans use averages that hide the long repairs.
How to Fix It
- Measure TAT by stepFor recent work orders, record induction, teardown, waiting on parts, repair, test and release dates. Find where the days go.
- Apply Little's LawTAT = work orders in process / work orders completed per week. At 60 open and 10 a week out, the average turn is ~6 weeks.
- Cap work orders in processInduct a new unit when one is released and hold the rest in a queue outside the shop. Lower the cap while output holds.
- Protect the constraintLoad the test stand or bay with all its demand. Keep it running through shift change and never let it wait on a unit that is not ready.
- Stage parts earlyKit the parts that are replaced on almost every repair before induction, and order from teardown findings the same day.
- Track the waitsPut waiting on parts, engineering and approval on the board, each with a target in days and an owner.
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Common Questions
Is turn time a labor problem?
Sometimes, but measure first. If most of the days are spent waiting on parts, a bay or a test stand, more mechanics will not shorten it.
Should we induct every unit when it arrives?
Not into a full shop. Inducting adds work orders in process and lengthens every turn. Hold units at receiving in a visible queue.
How do we plan when scope is unknown until teardown?
Plan with the spread, not just the average. Split work orders by type, plan each from its own history, and leave room at the constraint for the long ones.
What about AOG and other priority units?
Give them a set lane with a limit on how many can be open at once. If every unit is a priority, none is.