Engineering responsibility and errors in technical documentation: How far can you trust supplier data?

Engineering projects rely heavily on technical data provided by component manufacturers. Design calculations, 3D models, assembly concepts, and procurement decisions are often based on information published in supplier catalogues and technical documentation.

The underlying assumption is simple: if the data comes from a reputable manufacturer, it should be accurate.

In reality, however, even documentation issued by global industry leaders can contain errors. When this happens, an important question arises:

Who is responsible for the consequences—the supplier who provided incorrect information, or the engineer who incorporated it into the design?

A small catalogue error with real project consequences

During a recent engineering project, our team selected a bearing based on the technical documentation of a leading global manufacturer.

The component was integrated into the machine design without any indication of potential issues. However, during assembly, a discrepancy became apparent. The mounting hole specified by the manufacturer had a diameter of 11.5 mm, while the same documentation recommended the use of an M12 bolt.

A detailed review confirmed that the issue originated from an error in the supplier’s catalogue. The recommended fastener was incompatible with the dimensions of the mounting hole. The manufacturer has since been informed about the inconsistency.

While the issue itself was relatively minor, it highlights a challenge that engineering teams encounter more often than many would expect.

The engineering equivalent of the “Limited trust” principle

In road safety, there is a well-known concept often referred to as the principle of limited trust. Drivers are expected to follow the rules, but responsible road users remain aware that mistakes can happen.

The same principle applies to engineering.

Suppliers are expected to provide accurate technical information. Yet experience shows that engineers should not automatically assume that every dimension, specification, or recommendation is correct simply because it appears in an official catalogue.

This is not a question of distrust. It is a matter of engineering due diligence and risk management.

Should engineers verify supplier data?

There is no simple answer.

On one hand, engineering teams must be able to rely on supplier documentation. Verifying every dimension, tolerance, and interface of every purchased component would make many projects commercially unviable.

Modern machines may contain thousands of purchased parts sourced from dozens of suppliers. Conducting a full validation of every technical parameter would significantly increase project costs and extend development schedules.

On the other hand, the final responsibility for the functionality and manufacturability of a machine remains with the engineering team.

If an interference, dimensional conflict, or assembly issue can be identified during design reviews, 3D modelling, or validation activities, it is far more cost-effective to detect it before production begins.

This creates a balance that every engineering organisation must manage: trusting supplier data while maintaining sufficient verification processes to identify critical issues before they reach the shop floor.

The cost of discovering errors during assembly

Technical documentation errors rarely become visible when reviewing a catalogue.

Most often, they are discovered during manufacturing, assembly, commissioning, or site installation—when corrective actions are significantly more expensive.

Even a seemingly minor inconsistency can lead to:

• project delays,
• redesign activities,
• rework of manufactured parts,
• additional procurement costs,
• extended assembly and commissioning schedules,
• increased project risk and contractual exposure.

The later a problem is identified, the greater its impact on cost, schedule, and resource allocation.

Engineering is about risk management, not just design

Mechanical design engineering is often associated with calculations, CAD modelling, and technical drawings. In reality, successful engineering projects require much more.

Engineers must continuously identify potential risks, challenge assumptions, and evaluate information from multiple sources. Technical competence alone is not enough; effective engineering also requires critical thinking and professional judgement.

This is particularly important when integrating components supplied by different manufacturers, each operating under different standards, assumptions, and documentation practices.

How we minimise engineering risk at IBZ Engineering Group

At IBZ Engineering Group, we recognise that eliminating all engineering risk is impossible. Our objective is to reduce risk exposure through systematic verification and engineering review processes.

Our engineering approach includes:

• validation of interfaces between components from different suppliers,
• 3D clash detection and assembly feasibility analysis,
• verification of critical dimensions and functional requirements,
• structured design reviews conducted by experienced engineers,
• risk assessment of safety-critical and reliability-critical components,
• early identification of potential manufacturing and assembly challenges.

This does not mean validating every dimension of every purchased component. Such an approach would be neither practical nor economically justified.

Instead, we focus our engineering effort where the potential consequences of an error are greatest. This risk-based approach helps minimise costly surprises during manufacturing, assembly, and commissioning.

Trust is important. Verification is essential.

The case described above demonstrates that even documentation from highly respected suppliers can contain inconsistencies.

For engineering teams, the lesson is clear: supplier data should be trusted, but not accepted blindly.

Successful engineering projects depend on a combination of technical expertise, structured verification processes, and the willingness to question assumptions when something does not look right.

After all, the role of an engineer is not to correct the supplier’s catalogue.

The role of an engineer is to deliver a solution that works in the real world.

And sometimes, that requires questioning even the most trusted source of information.