Question 1

My storeroom already reports a fill rate. Why do I need this?

Accepted Answer

Because fill rate averages away the one number that matters. A 97% fill rate treats a $12 fuse and a 26-week-lead gearbox coupling as equal line items — but the fuse stocking out is a shrug and the coupling stocking out is a line-down event. Availability isn’t the risk. The risk is the gap between a spare’s replenishment lead time and the downtime you can tolerate on the asset it protects. This watchtower reads the same storeroom export and reports that gap per spare, so the critical coupling nobody stocked stops hiding inside a healthy-looking average.

Question 2

What are the two reads, and why keep them separate?

Accepted Answer

Coverage is the headline: STOCKED if you have one on hand, ORDER NOW if none on hand but one on a released PO, UNPROTECTED if you have neither. Exposure severity rides alongside as a separate read — what a stockout actually costs, from the asset’s criticality, whether the lead time exceeds tolerable downtime, and whether a substitute exists. They’re kept separate because they answer different questions. A spare can be STOCKED yet HIGH severity (you have one, but if it fails you’re exposed), or UNPROTECTED yet LOW severity (out of stock, but a substitute and a three-day lead make it a non-event). Collapsing them into one score would hide exactly the distinction that tells you what to buy first.

Question 3

Why did an out-of-stock spare read UNPROTECTED but only LOW severity?

Accepted Answer

Because being out of stock and being at risk are different things. Take a 10-amp control-panel fuse serving a minor asset: it’s out of stock (UNPROTECTED on coverage), but it has a qualified substitute and a three-day lead time, so a stockout costs you almost nothing — LOW severity. Contrast it with the gearbox coupling: also out of stock, but crit-A, no substitute, six-month lead. Same coverage state, opposite severity. Treating them as the same alarm is exactly how a storeroom wastes cash stocking fuses while the coupling that can down the line sits unprotected.

Question 4

What forces the SINGLE-FAILURE RISK verdict?

Accepted Answer

A dispositive cascade gate, worsen-only, that fires when four conditions are all true: the spare serves a criticality-A asset, there is nothing on hand and nothing on order, there is no qualified substitute, and the lead time exceeds the asset’s tolerable downtime. That is the precise state where one failure takes the line down with no recovery path inside the window you can absorb — the definition of a single point of failure in the storeroom. It releases the moment any single leg clears: stock or an order arrives, a substitute is qualified, or the lead time is brought inside the tolerable window. In the worked example the main drive coupling gates; qualify a substitute for it and it releases to HIGH.

Question 5

Does it connect to my CMMS or rank my suppliers?

Accepted Answer

Neither. You export the columns you already keep — asset criticality, tolerable downtime, lead time, on-hand, on-order, and whether a substitute exists, one row per spare — and the watchtower reads that file offline. It connects to nothing. It grades a spare’s stockout risk, never a person and never a named supplier; there is no field for who to blame. A SINGLE-FAILURE RISK verdict points at a part number to buy, not at a vendor to punish. It is not procurement, financial, or engineering advice.

Question 6

What do I get, and does the workbook match the tool?

Accepted Answer

You get a runnable Python engine (stdlib-only), a workbook that reproduces the identical two reads and verdicts (Start Here, Dashboard, Watchtower tabs), a seven-spare worked example, and two playbooks — a criticality-and-tolerance setup guide for classifying your spares honestly, and a stockout-closure runbook for buying in the order that removes the most single-failure risk per dollar. The engine, the workbook, and the on-page demo are verified to produce byte-exact matching reads on the shipped sample.

97% fill rate — rightuntil the coupling takes the line down.

Fill rate is an average. A single point of failure is not.

Read a spare twice. Watch coverage and severity disagree.

One command reads your storeroom export and names the spare to buy first.

Three rules keep the storeroom honest.

Two reads, never one score

Risk is lead time vs tolerance

Single-failure is dispositive

A stockout-risk watchtower, not an inventory optimizer or a supplier scorecard.

Anyone who owns a storeroom or the downtime it’s insuring against.

The plant reliability desk.

The Supplier-Concentration Risk Gate

PM Deferral & Pencil-Whip Tripwire

Manufacturing & Distribution Ops Pack

The honest answers.

Find the single point of failure
before it finds you.