How to control engineering changes when long-lead parts are already ordered

A customer increases the required lifting capacity of a bespoke crane while design work is still in progress. The change affects a machined pin and bearing arrangement. The original pin has already been ordered against revision A. The supplier may have committed material or already started manufacture.

Direct answer
When a long-lead part is already ordered, the team should first contain the commitment, then confirm the supplier and project state, make a controlled technical disposition and record the commercial and schedule consequences before releasing the new revision.

Committed changes need a different response

Before purchasing commits, the team can usually hold the release, review the new requirement and buy the correct item. After commitment, the old and proposed states both have operational consequences. The process must preserve the history and decide what happens to the existing order, material and work.

Containment depends on the current state

• Not yet ordered: hold release to procurement until the new revision is approved.
• Ordered, supplier not started: contact the supplier immediately and place the order on hold.
• Supplier manufacture started: confirm progress, committed material and possible modification or rework.
• Received or in stock: quarantine or clearly block the item from unintended issue.
• Allocated or issued to build: stop the affected task and identify every location and work order.
• Installed or tested: assess the physical configuration, safety, quality, customer and inspection consequences.

Separate technical disposition from commercial treatment

Engineering decides whether the previous component remains technically suitable. Procurement establishes supplier options and committed cost. The project manager assesses delivery, build sequence and customer effect. Quality identifies inspection, NCR, concession and document implications. Commercial authority decides what exposure the business can accept or recover.

These decisions are connected, but they should not be blurred. A part may be technically usable under an approved concession while still creating a schedule or customer-approval issue. A supplier may be able to rework the item, but only at a cost that requires management approval.

Five rules for committed parts

1. Do not delete the old revision or hide the original commitment. The history is part of the project record.
2. Do not assume a bespoke part is waste. Assess whether it can be reworked, reallocated or used under an approved decision.
3. Do not leave unsuitable material in normal available stock. Apply a clear hold, quarantine or obsolete status.
4. Keep cancellation, scrap, rework and replacement cost against the project.
5. Update shortages and build readiness immediately so the workshop sees the real position.

Worked scenario: the lifting requirement changes

• Engineering creates revision B while revision A remains in controlled history.
• The change record identifies the pin, bearing arrangement, drawings, BOM positions and affected assembly.
• Procurement confirms the revision A purchase order and asks whether manufacture has started.
• The project manager reviews cost, lead time, build sequence and delivery impact.
• The original order is amended or cancelled where possible, and unavoidable cost remains visible.
• The revision A item is placed on hold while engineering decides its disposition.
• Revision B is approved and released, and the purchase order is raised or amended against the correct state.
• Stock reservations, shortages and work orders are updated before the affected assembly begins.
• The previous drawing remains available for audit but is no longer an approved production document.
• The final pack contains the approved revision B drawing, correct certificates and traceable change history.

What the decision record should show

• Reason for change and affected controlled items.
• Previous approved state and proposed state.
• Existing supplier, stock, build and document exposure.
• Decision, conditions and named actions.
• Disposition of the previous component or order.
• Cost and schedule consequences.
• Evidence that the PO, stock status, work order, drawing and final documents were updated.

Answer-ready FAQ

What should happen when a design changes after a part is ordered?

Place the affected commitment on hold where possible, confirm supplier progress, assess technical and commercial consequences, then decide whether to amend, cancel, continue, rework or accept.

Should an obsolete bespoke part always be scrapped?

No. Engineering should decide whether it can be reworked, reallocated, used under an approved concession or retained for another approved purpose.

How should cancellation and rework cost be recorded?

Keep cancellation charges, scrap, rework and replacement costs against the project so the true commercial effect remains visible.