Incorporated Engineer (IEng) Design, Development and Application of Solutions (UK-SPEC Competence B) Syllabus

What is Design for Maintainability (DfM/maintenance)?

Designing equipment so it can be inspected, serviced and repaired quickly and safely: good access, modularity, standard fasteners, diagnostic features and easily replaceable components, reducing mean time to repair.

Define whole-life cost (life-cycle cost).

The total cost of an asset over its entire life: acquisition (capital) plus operation, maintenance, downtime, and disposal costs. $LCC = C_{acq} + C_{op} + C_{maint} + C_{disposal}$ (often discounted to present value).

Why is whole-life cost preferred over purchase price when appraising designs?

Because the largest share of cost is often incurred during operation and maintenance, not purchase. A cheaper item to buy may have higher running, energy or disposal costs, making it more expensive over its life.

What is the recommended process for implementing a design change or modification?

Raise a change request, assess impact (cost, safety, schedule, interfaces), obtain approval through change/configuration control, update documentation and baselines, implement, then verify and validate the change.

Distinguish verification from validation.

Verification asks 'did we build the product right?' — does it meet the specification. Validation asks 'did we build the right product?' — does it meet the user's actual needs in the operating environment.

List four common testing types used to confirm a design meets specification.

Unit/component testing, integration testing, system testing, and acceptance testing. Others include functional, performance, environmental, and regression testing.

What is a Factory Acceptance Test (FAT) versus a Site Acceptance Test (SAT)?

A FAT verifies the equipment against specification at the manufacturer's premises before shipment; a SAT verifies it again after installation at the operating site to confirm correct integration and on-site performance.

What is the purpose of evaluating outcomes after implementation?

To compare actual performance against the original objectives, success measures and acceptance criteria, identify shortfalls and lessons learned, and propose improvements for the current and future designs (continuous improvement).

Name a structured continuous-improvement cycle used to drive design improvements.

The PDCA (Plan-Do-Check-Act) Deming cycle; also DMAIC (Define, Measure, Analyse, Improve, Control) from Six Sigma.

What is a design review?

A formal, documented, systematic examination of a design by competent reviewers at defined stages (gates) to evaluate whether it meets requirements, identify problems early, and authorise progression to the next phase.

List typical formal design-review stages (gates) in a project.

Requirements/System Review (SRR), Preliminary Design Review (PDR), Critical Design Review (CDR), Test Readiness Review (TRR), and Production/Final Design Review. They act as go/no-go decision gates.

What is configuration management?

The discipline of identifying, controlling, recording the status of, and auditing the configuration items of a product throughout its life, ensuring consistency between the product, its requirements, and its documentation.

State the four main functions of configuration management.

Configuration identification, configuration control (change control), configuration status accounting, and configuration audit/verification.

What is a configuration baseline?

A formally reviewed and agreed reference version of a configuration item (e.g. requirements, design, build) that serves as the basis for further work and can only be changed through formal change control.

Name and distinguish the three principal maintenance strategies.

Corrective (reactive) — repair after failure; Preventive — scheduled at fixed time/usage intervals to prevent failure; Predictive (condition-based) — maintenance triggered by monitored condition indicating impending failure.

What is the main disadvantage of a purely corrective (run-to-failure) maintenance strategy?

Unplanned downtime, potential safety/consequential damage, higher repair costs and disruption, because failures occur without warning. It is acceptable only for non-critical, low-cost items.

What is the difference between preventive and predictive maintenance triggers?

Preventive is triggered by elapsed time or usage (calendar/hours/cycles) regardless of actual condition; predictive is triggered by the measured condition of the asset, performing maintenance only when data indicates it is needed.

What is Reliability-Centred Maintenance (RCM)?

A structured method that determines the most effective maintenance strategy for each asset based on its functions, failure modes and consequences, selecting corrective, preventive, predictive or redesign as appropriate to preserve function at least cost.

Define reliability in the RAM context.

The probability that an item performs its required function under stated conditions for a specified period of time without failure. It is concerned with avoiding failure.

Define maintainability in the RAM context.

The ease and speed with which an item can be restored to operating condition after failure, usually measured by the Mean Time To Repair (MTTR). It reflects how quickly maintenance can be performed.

Define availability and give its steady-state formula in terms of MTBF and MTTR.

Availability is the proportion of time an item is in a functioning, ready-to-use state. $$A = \frac{MTBF}{MTBF + MTTR}$$

What does MTBF stand for and how is it defined?

Mean Time Between Failures — the average operating time between failures of a repairable item: $MTBF = \frac{\text{total operating time}}{\text{number of failures}}$.

What is the difference between MTBF and MTTF?

MTBF (Mean Time Between Failures) applies to repairable items and measures time between successive failures; MTTF (Mean Time To Failure) applies to non-repairable items and measures the average time to the single failure that ends life.

State the relationship between failure rate $\lambda$ and MTBF for a constant failure rate.

For a constant (random) failure rate, MTBF is the reciprocal of the failure rate: $$MTBF = \frac{1}{\lambda}.$$

Give the reliability function for an item with a constant failure rate $\lambda$.

The reliability at time $t$ follows the exponential law: $$R(t) = e^{-\lambda t}.$$

Describe the three regions of the bathtub curve.

1) Infant mortality / early life — decreasing failure rate (manufacturing/installation defects); 2) Useful life — constant, low random failure rate; 3) Wear-out — increasing failure rate as the item ages and degrades.

How does reliability combine for components in series versus in parallel?

Series (all must work): $R_{s}=\prod_{i=1}^{n} R_{i}$. Parallel/redundant (one must work): $R_{p}=1-\prod_{i=1}^{n}(1-R_{i})$.

What is root cause analysis and name two common techniques.

A systematic process to identify the underlying cause of a failure (not just symptoms) so it can be permanently eliminated. Techniques include the '5 Whys' and the Ishikawa (fishbone/cause-and-effect) diagram; also Fault Tree Analysis and FMEA.

What is FMEA and what is the Risk Priority Number?

Failure Mode and Effects Analysis systematically identifies potential failure modes and their effects. The Risk Priority Number ranks them: $RPN = S \times O \times D$ (Severity × Occurrence × Detection), prioritising actions on the highest values.

What is condition monitoring and give three example techniques?

Condition monitoring measures parameters that indicate machine health to detect developing faults. Examples: vibration analysis, oil/lubricant (tribology) analysis, thermography, and acoustic emission. It underpins predictive maintenance.

What is asset obsolescence management and why is it important?

The proactive identification and mitigation of components, software or technology becoming unavailable or unsupported over an asset's life. It is important to avoid forced downtime, costly redesign and loss of support, planning last-time buys, redesign or substitution in advance.