D2: Problem Description — 5W2H Framework

Part of the 8D methodology (D0–D8).

Discipline 2 (D2) is the foundation of the entire 8D. In the words of Charles Kettering, "A problem well-stated is a problem half-solved." D2 uses the 5W2H framework to create a precise, data-driven "Problem Statement" that eliminates ambiguity.

1. The 5W2H Deep Dive A professional D2 description answers these seven questions with specific data, not generalizations: - Who: Which customer reported it? Which operator was on the line? Which inspector missed it? - What: What exactly is the defect? Describe the physical failure mode in technical terms (e.g., "0.5mm radial crack at the P3 solder joint"). - Where: Where was the defect detected? (At the customer? Final test? IPQC?). Where on the part is the defect located? (Top, bottom, internal?). - When: When was it detected? When was the part manufactured? This requires looking at shift logs and date codes. - Why: Why is this a problem? This refers to the specification. For example, "Spec requires >10kg pull force; actual batch tested at 4kg." - How: How was the defect detected? (Manual inspection, AOI, Functional test, or field failure). - How Many: What is the magnitude? Total suspect population vs. actual defect count. Calculate the PPM (Parts Per Million) to understand the severity.

2. Worked Example: A Complete D2 Statement A supplier receives a field complaint on a motor assembly. The team drafts the following statement, filling each 5W2H slot with verified data:

| Element | Entry | |---|---| | Who | End customer, reported through the regional service centre; detected on units built on Line 2, night shift | | What | High-frequency whine measured at 45 dB at 3000 RPM; bearing seat shows 0.08 mm radial play against a 0.03 mm maximum | | Where | Detected in the field (audible to the user); defect located at the drive-end bearing seat, internal | | When | Detected in service; date codes from two consecutive production weeks (weeks 14–15) | | Why | Specification allows max 0.03 mm radial play and max 38 dB at 3000 RPM; measured values exceed both | | How | Field failure, confirmed on the return bench with a sound-level meter and bore gauge | | How Many | 37 confirmed failures out of 12,400 suspect units shipped = approx. 2,984 PPM |

Note that every line carries a number or a verifiable location. "Noisy motor" has been replaced by a measurable deviation from a named specification.

3. Is/Is-Not vs 5-Why: Which Comes First? One of the most effective tools in D2 is comparing the problem to what it is *not*. - Is: The crack appears on parts made with Tool A. - Is Not: The crack never appears on parts made with Tool B. This comparison immediately narrows the in