Question 23.2: ASSESSMENT OF RISK Assess the risk for an automated mountain...
ASSESSMENT OF RISK
Assess the risk for an automated mountain climbing rig.
A sample FMECA is illustrated in Fig. 23.13. The system being assessed is an automated mountain climbing rig. Table 23.3 illustrates the breakdown and coding of the system into subsystem, assembly, and subassembly elements. An FMECA worksheet for the control subsystem is presented in Table 23.4.
Table 23.3 System breakdown and coding for Example 23.2
| Subsystem | Assembly | Subassembly |
| Hoist (A) | Motor (A-01) | Windings (A-01-a) |
| Inboard bearing (A-01-b) | ||
| Outboard bearing (A-01-c) | ||
| Rotor (A-01-d) | ||
| Stator (A-01-e) | ||
| Frame (A-01-f) | ||
| Mounting plate (A-01-g) | ||
| Wiring terminals (A-01-h) | ||
| Drum (A-02) | ||
| External power source (B) | ||
| Cage (C) | Frame (C-01) Lifting lug (C-02) |
|
| Cabling (D) | Cable (D-01) Hook(D-02) Pulleys (D-03) |
|
| Controls (E) | Electrical (E-01) Operator (E-02) |
START Switch (E-01-a) FULL UP LIMIT Switch (E-01-b) Wiring (E-01-c) |
Table 23.4 Failure modes, effects, and criticality analysis for Example 23.2
| FMEA NO:___ PROJECT NO:___ SUBSYSTEM NO: Controls SYSTEM NO: Mountain Climbing Rig PROB. INTERVAL: 30 years |
FAILURE MODES, EFFECTS, AND CRITICALITY ANALYSIS WORKSHEET |
SHEET____OF___ DATE___ PREPARED BY:___ REVIEWED BY:___ APPROVED BY:___ |
|||||||
| TARGET/RESOURCE CODE: P-PERSONNEL/E-EQUIPMENT/T-DOWNTIME/R-PRODUCTS/D-DATA/V-ENVIRONMENT |
|||||||||
| Id. No. | Item/ Functional Identification |
Failure Mode | Failure Cause | Failure Event | Target | Risk Assessment | Action Required/ Comments |
||
| Sev | Prob | Risk Code |
|||||||
| E-01-a | Start Switch | Switch fails closed. |
Mechanical failure or corrosion. |
Cage will not move. |
P E T |
IV IV IV |
C C C |
3 3 3 |
|
| E-01-b | Full Up Switch | Switch fails open. |
Mechanical failure or corrosion. |
Cage does not stop. |
P | II | A | 1 | |
| E-02 | Wiring | Cut, Disconnected. |
Varmint invasion, faulty assembly |
No response a switch. Start switch fails open. Stop switch fails closed. Cage stays in safe position. |
P E T |
IV IV IV |
D D D |
3 3 3 |
|
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