Khóa học phân tích nguyên nhân gốc Root Cause Analysis (RCA)

1. Root Cause Analysis (RCA) la gi? Tai sao can RCA?

Root Cause Analysis (RCA) — Phan tich nguyen nhan goc la qua trinh xac dinh nguyen nhan thuc su cua mot van de, de dat ra giai phap xoa bo nguyen nhan do, ngan chan van de tu phat lai. Khac voi “Direct Cause” (nguyen nhan truc tiep) va “Contributing Cause” (nguyen nhan dong goi), Root Cause la nguyen nhan ma neu duoc loai bo, van de se KHONG BAO GIO XAY RA LAI.

Tai sao can RCA?

• Giam chi phi: 1 loi phat hien tai Field = 10x chi phi tai Plant = 100x chi phi tai Design (Rule of 10). RCA tai giai doan som tiet kiem tien khung.
• Ngan chan phat lai: Khong RCA -> “Firefighting” (chay chua chay) hang ngay. Co RCA -> He thong on dinh.
• Bat buoc chuan: IATF 16949 (Clause 10.2.3), ISO 9001, FDA 21 CFR 820, GMP, AS9100 deu yeu cau RCA cho nonconformity.
• Hoc to chuc: Moi RCA la mot bai hoc. Tap hop RCA = Tri thuc to chuc (Organizational Knowledge).

Quy tac vang RCA: “Neu ban khong co thoi gian lam dung lan dau, ban se co thoi gian lam lai lan thu hai.” — RCA lam dung lan dau.

2. 5 Why – Phuong phap co ban nhat (Toyota)

5 Why hoi “Tai sao?” 5 lan (hoac nhieu hon) de sau bop mat na cua symptom. Quoc gia xuat xu: Toyota (Taiichi Ohno).

Vi du that (Taiichi Ohno, Toyota):

1. Tai sao may dung? -> Qua tai (Overload) -> Fuse duc.
2. Tai sao qua tai? -> Banh phu khong boi tron duoc.
3. Tai sao khong boi tron? -> Bom boi tron hong.
4. Tai sao bom hong? -> Truc quay moc (Shaft worn) -> Khong co lop nguon.
5. Tai sao khong co lop nguon? -> Khong co bo loc (Filter) tren bom.

Root Cause: Thieu bo loc tren bom boi tron. Giai phap: Lap bo loc. Khong chi doi fuse.

Loi thich gap khi dung 5 Why:

• Dung som (chi 2-3 Why) -> Chi tim duoc Direct Cause.
• Chuyen huong sang nguoi (Blame people) -> “Nhan vien khong chuan” — KHONG PHAI ROOT CAUSE. He thong cho phep loi xay ra moi la root cause.
• Khong co bang chung (Data) cho moi Why -> Suy doan.
• Khong phan biet Common Cause vs Special Cause.

5 Why Template (Excel cung cap):

• Problem Statement (5W2H)
• Why 1 -> Evidence -> Why 2 -> Evidence … -> Root Cause
• Countermeasure cho tung Root Cause
• Verification plan

3. Fishbone (Ishikawa) – Phan tich nguyen nhan he thong

Fishbone Diagram (Cause & Effect Diagram) phat minh boi Kaoru Ishikawa. Phan loai nguyen nhan theo 6M (hoac 4M, 8M):

• Man (Nhan vien): Skill, Training, Fatigue, Motivation, Communication
• Machine (May moc): Maintenance, Calibration, Tooling, Fixture, Age
• Material (Vat lieu): Spec, Lot variation, Storage, Handling, Shelf life
• Method (Phuong phap): SOP, Work Instruction, Setup, Changeover, Sequence
• Environment (Moi truong): Temperature, Humidity, Lighting, Noise, Vibration, Cleanliness
• Measurement (Do luong): Gage R&R, Calibration, Resolution, Bias, Linearity
• Management (Quan ly) – M mo rong: Scheduling, Priority, Resources, Culture, KPI
• Mother Nature (Tu nhien) – M mo rong: Raw material variation, Weather, Force majeure

Quy trinh ve Fishbone:

1. Viet Problem Statement o “Dau ca” (Right side).
2. Ve “Xuong song” ngang.
3. Them 6M la cac “Xuong phu”.
4. Team brainstorming: Viet moi nguyen nhan vao xuong phu dung M.
5. Moi nguyen nhan -> Hoi “Tai sao?” -> Them xuong con (Sub-cause).
6. Danh dau * cho nguyen nhan co the kiem soat (Controllable).
7. Vote / Data analysis -> Chon Top 3-5 nguyen nhan co kha nang cao nhat.
8. Verify bang data (Check sheet, Pareto, Hypothesis test).

4. Fault Tree Analysis (FTA) – Cay loi

FTA la phuong phap Top-Down (nguoc voi Fishbone Bottom-Up). Tu Su kien khong mong muon (Top Event) -> Phân tich cac loi logic (AND/OR Gate) den Basic Events.

Ky hieu FTA:

• Top Event: Hinh tron (Su kien khong mong muon)
• OR Gate: Hinh tron cong voi dau + (Bat ky input nao xay ra -> Output xay ra)
• AND Gate: Hinh tron cong voi dau . (Tat ca input phai xay ra -> Output moi xay ra)
• Basic Event: Hinh vuong (Nguyen nhan goc, khong phan tich nua)
• Undeveloped Event: Hinh thoi (Chua co du lieu de phan tich)
• Conditional Event: Hinh ellip (Dieu kien)

Ung dung:

• Safety Critical Systems (Nuclear, Aerospace, Automotive ISO 26262)
• Quantitative FTA: Tinh xac suat Top Event tu xac suat Basic Events.
• Minimal Cut Sets: Tim tap hop nho nhat Basic Events de gay ra Top Event.

5. Apollo RCA – Phuong phap hien dai (Apollo Root Cause Analysis)

Apollo RCA (Sologic) la phuong phap he thong hop Fishbone + 5 Why + Logic Gate. 4 buoc:

1. Define: Problem Statement (What, When, Where, Impact).
2. Analyze: Cause & Effect Chart (Logic tree: Cause -> Effect). Moi cause phai co Evidence.
3. Solve: Solutions cho moi Cause. Phan loai: Corrective (Root), Preventive (Systemic), Contingent (Detection).
4. Report: Executive summary, Chart, Solutions, ROI, Lessons Learned.

Apollo khac Fishbone o cho: Logic gates (AND/OR) giua cac cause, Evidence-based (moi cause phai co data), Software ho tro (Apollo Root Cause Analysis Software).

6. Kepner-Tregoe (KT) Problem Analysis

KT Problem Analysis (Phan tich van de Kepner-Tregoe) — phuong phap co cau truc chuan cho quyet dinh quan ly. 4 buoc:

1. Situation Appraisal: Liet ke tat ca van de, uu tien (Seriousness, Urgency, Growth).
2. Problem Analysis: Specify Problem (IS/IS NOT) -> Identify Distinctions -> Identify Changes -> Test Causes -> Verify Root Cause.
3. Decision Analysis: Clarify Purpose -> Identify Alternatives -> Evaluate Alternatives -> Make Decision.
4. Potential Problem Analysis: Identify Potential Problems -> Likelihood/Seriousness -> Preventive Actions -> Contingent Actions.

IS/IS NOT Matrix la tim nhat cua KT: Viet cai GI (IS) va cai KHONG PHAI GI (IS NOT) cho Problem. Tim Distinction (Khac biet) -> Tim Change (Thay doi) -> Test Cause.

7. RCA trong 8D, DMAIC, CAPA

Framework	RCA o dau?	Phuong phap khuyen nghi
8D (IATF 16949)	D4 (Root Cause Analysis)	5 Why + Fishbone + IS/IS NOT. Bat buoc verify D5.
DMAIC (Six Sigma)	Analyze Phase	Hypothesis Test, Regression, Fishbone, FTA. Data-driven.
CAPA (FDA/ISO 13485)	Investigation	KT Problem Analysis, Apollo RCA. Documentation nang.
Layered Process Audit	Finding follow-up	5 Why nhanh (3-5 phut) tai Gemba.

8. Template & Tool cung cap trong khoa

1. 5 Why Template (Excel, co Evidence column, Verification column)
2. Fishbone Diagram Template (Excel + PowerPoint, 6M/8M)
3. Fault Tree Analysis Template (Excel, AND/OR gate, Basic Event probability)
4. Apollo RCA Logic Tree Template (Excel, Cause->Effect, Evidence)
5. KT IS/IS NOT Matrix (Excel)
6. RCA Report Template (Word, chuan 8D/DMAIC/CAPA)
7. Pareto Chart Template (Excel, 80/20 auto)
8. RCA Tracking Log (Excel, dashboard: Open/Closed, Aging, Recurrence)

9. Lien he tu van

Hotline: 098 905 1920 (Chi Dung)

Email: dung.truong@lean.vn

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