CRE Design for Reliability 2

Question 1

In a Fault Tree Analysis (FTA), which gate represents an output event occurring only if ALL input events occur simultaneously?

Accepted Answer

AND gate

Answer

OR gate

Answer

Inhibit gate

Answer

Priority AND gate

Question 2

Common Cause Failures (CCF) are particularly dangerous in redundant systems because they:

Accepted Answer

Can simultaneously defeat multiple redundant elements from a single shared cause

Answer

Only affect series-connected components

Answer

Are always detected by Built-In Test Equipment (BITE)

Answer

Only occur in software-intensive systems

Question 3

Highly Accelerated Life Testing (HALT) is primarily used during the design phase to:

Accepted Answer

Quickly find design weaknesses and operational/destruct limits by stressing beyond normal operating conditions

Answer

Certify a product meets its published MTBF specification

Answer

Validate the reliability of parts sourced from new suppliers

Answer

Demonstrate compliance with MIL-STD-810 environmental specifications

Question 4

Tolerance design (Taguchi method) in Design for Reliability focuses on making a design:

Accepted Answer

Robust and insensitive to variations in materials, manufacturing, and environment

Answer

Meet the tightest possible tolerances to eliminate all variability

Answer

Compliant with the minimum number of regulatory standards

Answer

Cost-optimized by using the widest possible tolerances on all components

Question 5

Which reliability prediction standard is most commonly used for electronic components in US defense and aerospace applications?

Accepted Answer

MIL-HDBK-217

Answer

IEC 61709

Answer

Telcordia SR-332

Answer

FIDES Guide

Question 6

What is the primary objective of sneak circuit analysis (SCA) in system design?

Accepted Answer

To detect unintended electrical paths or conditions that can cause unwanted functions without component failure

Answer

To identify components operating above their derating levels

Answer

To verify that FMEA critical items have adequate redundancy

Answer

To simulate fault propagation through a reliability block diagram

Question 7

During Design for Reliability, 'design margins' are established to:

Accepted Answer

Provide a buffer between the design's rated capability and the anticipated worst-case operating stress

Answer

Define the cost budget allocated to reliability improvement activities

Answer

Set the minimum acceptable MTBF for each subsystem

Answer

Determine the number of prototypes required for qualification testing