Human error and/or incompetence are unacceptable in the critical aerospace industry. This article explains how we can minimize the effects of people-related issues.
There are many versions of the Ishikawa or fishbone diagram, synonymous among industry professionals with problem solving. In most versions, people comprise one of the potential causes of issues and represent one of the areas for analysis.
No matter how many procedures are written, automated systems implemented or mistake-proofing measures instituted, where there are people there will be variation. For critical industries such as aerospace, variation is distinctly undesirable. Variation represents an opportunity for error to disrupt a process and potentially impact product integrity.
According to Ben Marguglio, a leading authority on human-error prevention/reduction, this branch of the fishbone diagram can be divided into seven different types of human error.
- Knowledge-based — Error based on the absence of knowledge of the requirement, expectation or need
- Cognition-based — Error based on the absence of ability to process the knowledge necessary to fulfil the requirement, expectation or need
- Value-based — Error based on the absence of willingness to accept the requirement, expectation or need
- Reflexive-based — Error based on the absence of ability to immediately respond to a stimulus
- Error-inducing, condition-based — Error based on the absence of ability to counteract the error-inducing condition
- Skill-based — Error based on the absence of manual dexterity
- Lapse-based — Error based on the absence of attention
One major aerospace airframer reports an example where subcontracted work was not carried out properly by the supplier. As a result, a crucial step was missed, resulting in a part that cracked while in use. This was a part that needed to be welded and then X-rayed to validate the integrity of the weld. Following that, shot peening was to be used to produce a compressive residual-stress layer and modify mechanical properties of the material before another X-ray was done to check the final part.
Due to a combination of misunderstanding of the whole process and commercial pressures to deliver the part quickly, the first X-ray was not done. The shot peening modified the material to such an extent that the second X-ray – in this instance, the only X-ray – did not highlight the fact that the weld was not done correctly, and air was trapped in the part. This ultimately led to failure.
Following Marguglio’s model, this was caused by a combination of knowledge-based, cognition-based and value-based human error.
In this instance, the part was not critical and the impact was quickly contained. But the repercussions of a situation like this are far-reaching. Root-cause analysis must be conducted and all causes identified and resolved. This is a complex activity that takes time and costs money for all involved.
There is always the potential for error when people are involved in a process. But a new initiative in the aerospace industry aims to counteract human errors that are knowledge-, cognition-, value- and error-inducing/condition-based.
eQuaLified is a global industry-managed system for qualifying special-process aerospace personnel. Many large aerospace organizations already operate their own special-process examinations internally and throughout their supply chains to ensure that their specifications and requirements are understood and that the individuals on whom they rely are sufficiently knowledgeable to implement them effectively.
eQuaLified takes this one step further by identifying common expectations within the aerospace industry and developing industry-wide Bodies of Knowledge and examinations. The Bodies of Knowledge describe the competency of an individual to perform a specific process (e.g., pyrometry). In effect, the industry is writing the ideal-person specification, including technical knowledge, experience, personal attributes, skills and non-special-process-related requirements.
Other areas within heat treating include: aluminum, including casting, forging, and wrought; light alloys (non-aluminum), including beryllium/copper and magnesium alloys; stress relief; steel alloy and carbon, including corrosion-resistant austenitic, corrosion-resistant martensitic and corrosion-resistant precipitation hardening; surface hardening, including carburizing gas, nitriding ion, nitriding gas and induction hardening; titanium nickel cobalt and special-purpose alloys, including titanium alloys, nickel-cobalt alloys and magnetic alloys; and hipping.
Aerospace-industry representatives identify those special-process areas in most need of personnel qualification and work together to develop the Bodies of Knowledge. For pyrometry, these have been split out into in-house pyrometry and outsourced pyrometry because the expectations of the individuals working in those areas have slight differences.
Honeywell Aerospace’s Laurie Strom, chair of eQualified and director of Materials and Process Engineering, had this to say: “Pyrometry provides a great case study to explain the value of eQuaLified. SAE International publishes AMS 2750, currently at revision E. This specification covers pyrometric requirements for thermal-processing equipment used for heat treatment. It covers temperature sensors, instrumentation, thermal-processing equipment, system accuracy tests and temperature uniformity surveys. These are necessary to ensure that parts or raw materials are heat treated in accordance with the applicable specification(s). AMS 2750 is widely accepted by the aerospace industry as the fundamental document for pyrometry. Special-processor compliance to the requirements of AMS 2750 in aerospace is validated via the Nadcap heat-treatment audit. But key to that compliance is ensuring that the personnel are in place with the ability to appropriately interpret, implement and adapt to the requirements of AMS 2750. eQuaLified is the medium to achieve this.”
All Bodies of Knowledge are published online at www.p-r-i.org/professional-development/qualifications/bodies-of-knowledge/. These documents are publicly available for the benefit of the industry to support training, recruitment and other professional development activities.
To complement the Bodies of Knowledge, the industry is also writing examinations to validate personnel competency. The Bodies of Knowledge define the “perfect” personnel for a particular special-process role, and the examinations qualify individuals against those criteria. Examination questions follow the structure and content of the Body of Knowledge.
To date, the focus has been on online theoretical examinations, with practical exams to follow. In some areas, theoretical knowledge may be sufficient, but in others, hands-on competency must also be confirmed.