TS EN 9138

TS EN 9138 is an aerospace quality management standard focused on how statistical product acceptance methods are applied. Its emphasis is not limited to sampling logic alone; it also addresses a risk-based acceptance approach, traceability, characteristics linked to safety or criticality, and the minimum documented procedure content needed to control those methods.

What statistical product acceptance is meant to control

In general technical terms, statistical acceptance evaluates product conformity from a defined sample rather than inspecting every item individually. The aim is to represent the lot or process reliably while managing acceptance risk and customer risk. In aerospace and related supply chains, this becomes especially important because of traceability needs, critical characteristics, and characteristics that can affect safety. TS EN 9138 places that general approach alongside the EN 9100, EN 9110 and EN 9120 quality management system standards and requires a minimum documented procedure framework for implementation.

Where the standard applies

• It applies when invoked by a purchasing contract, specification, contractual document, customer agreement, or by the organization itself.
• Clauses 4 and 5 apply to all statistical methods of product acceptance.
• Clause 6 covers acceptance of product produced by individual lots.
• Clause 7 covers acceptance under switching rules.
• Clause 8 covers acceptance under process controls; Clause 9 covers continuous sampling or special case methods.

This makes the standard more than a description of a sampling technique. It defines the conditions under which an acceptance method is used, the rules governing its application, and the documented process that supports it. Its attention to retrievability, safety-related characteristics, and quality parameters shows why product acceptance in aerospace needs tighter control than a generic quality check.

In practice, standards of this type help organizations make consistent acceptance decisions across the supply chain, manage transitions between different acceptance methods in a controlled way, and keep procedures auditable. Product acceptance then becomes not just a statistical calculation, but a managed and recorded quality process.