1. Task Analysis, Failure Modes and Effects Analysis

2. Task Analysis Purpose Take modeling & analysis to the next level.
Summarize what is known about task in one place.
Prepare for FMEA, detailed requirements development.
Method (HMSEM)
Apply to most primitive processes/activities in IDEF0 model
i.e., ones with no child diagrams
Fill in one row in [Summary] sheet in HMSEM workbook
Task Analysis columns (R - W)
Detail important task characteristics (Purpose, Location, etc.)
Other Approaches
Hierarchical Task Analysis

3. HTA of Cesarean Delivery Process ≈IDEF0 Nodelist

4. Example: Pre-Reflow Inspection Station (PRIS) Task Analysis

5. PRIS Hierarchical Task Analysis (Process/Task Hierarchy)
A0: Assemble Electronics Components
A1: Set Up Oven & Dispenser (Initial)
A2: Program & Set Up SMT
A3: Dispense Solder On Board
A4: Place Component
A5: Perform Pre-Reflow Inspection & Place Manual Components
A51: Prepare & Review Documents
A52: Program Reflow Oven
A53: Inspect Board
A531: Compare Board Match
A5311: Study iView Diagram
A5312: Study Individual Component / Group
A532: Check Components (Loose, Misaligned, Skewed)
A5321: Study iView for Check Components
A5322: Assess Individual Component / Group (for Check Components)
A5323: Adjust Parts (When needed)
A533: Check Component Population (1st Board Only)
A5331: Study iView Component Population
A5332: Assess PCB Population
A534: Check Component Orientation/Direction (1st Board Only)
A5341: Study iView and OPIE
A5342: Visually Assess Placement of the Component
A54: Install Manual Components
A6: Reflow

6. PRIS Task Analysis in HMSEM Workbook

7. Task Analysis Fields Purpose / Value Added why the task is necessary
what value is added by performing the task
Location
where the task is performed
Frequency & Timing
Environmental Conditions
illumination, lighting (lux, fc)
temperature (deg)
humidity (%)
vibration, acceleration
other
Information Requirements
information needed to perform the task
Sensory / Cognitive / Motor Action
sensing, memory, actions required to perform task

8. Some Sensory / Cognitive / Motor Action Verbs
Attend to
Detect
Distinguish between
Feel
Hear
Read
View
Remember
Calculate
Count
Decide among
Estimate
Evaluate
Generate
Predict
Process
Configure
Disengage
Engage
Grasp
Manipulate
Move
Open
Pick up
Position
Press
Reach to
Release
Transfer
Turn
Wait for
Walk to

9. Failure Modes and Effects Analysis (FMEA)
Purpose
Systematically, prospectively, identify ways in which a process (system) can fail: Failure Modes.
Identify factors potentially contributing to failures.
Estimate risk of failure
Identify countermeasures
Develop requirements
Method (HMSEM)
Select task on which to perform FMEA (TA should have been completed on it)
Prepare task FMEA worksheet from [template] worksheet
copy [template] worksheet
rename new task FMEA worksheet to task's A-number
copy task row from [Summary] worksheet to row 6 of new task FMEA worksheet
(optionally) hide non-FMEA columns (A-Z)
Perform FMEA

10. PRIS FMEA in HMSEM Workbook

11. FMEA Fields Contributing Factors
Circumstances, conditions, events, factors, ... anything that might make a failure mode more likely.
Potential Failure Mode
A way in which the process/system can fail.
Potential Effects of Failure Mode
Consequences of the failure.
Severity
Numeric rating of the estimated severity of consequences, of the failure, e.g.,
negligible
minor
moderate
major
catastrophic

12. FMEA Fields (2) Probability
Numeric rating of the estimated probability that the failure will occur, e.g.,
Remote
Unlikely
Occasional
Common
Frequent

13. FMEA Fields (3) Nondetectability
Numeric rating of the difficulty of detecting the failure in time to prevent or mitigate its consequences, e.g.,
Should the failure occur, there is a virtual certainty that the existing controls will detect it.
Very high
Should the failure occur there is a high probability that the existing controls will detect it.
Moderately high
Existing controls have difficulty detecting the failure
Low
Controls are weak. Detection could depend on a lucky catch.
Remote
Very remote
No controls for this failure mode exist
RPN: Risk Priority Number
RPN = Probability x Severity x Nondetectability

14. FMEA Fields (4) Potential Remediations
Design strategies that could reduce the likelihood of the failure mode.
Design Requirements
Abbreviated requirements statements for remediations.
Requirement numbers ([Requirements] worksheet).