Product quality is important in many applications. Aerospace applications have particularly high product quality standards due to the extreme conditions the parts are designed to meet. In aerospace applications components may be operated at up to 50,000 rpm. Some components can be expected to last over 30 years.

In addition, the aerospace industry is heavily regulated.  Aerospace OEMs, or Primes, make significant efforts to control the supply chain so they can ensure the quality of components being supplied.  

Over the years, many specifications and standards have been created to control aerospace suppliers, including ISO standards, and more recently the AS9100 standard. Over time, the AS9100 standard has been modified to match the ISO 9001 standard and add additional clauses that the aerospace industry felt were needed.

In 1990, Nadcap was created as “an industry-managed, consensus approach to OEM oversight of special process and product suppliers.”

In 2014, Nadcap created the Metallic Materials Manufacturing (MMM) Task Group. This task group covers forgings, castings, and raw materials. At this time, only the forging audit criteria, AC7140, has been issued.  It was originally issued June 5, 2016 and it is now on its second revision. Some OEMs have issued mandates and are requiring their forging suppliers to be accredited within varying deadlines but with some due by the end of 2018.

The foundry audit criteria are currently in development and have been for some time. The task group is developing a sand-casting checklist and an investment casting checklist. The MMM task group has also established qualifications to be a foundry auditor. A Castings Audit Handbook is also under development.

It is not clear when the audit criteria will be completed. Once completed, the audit criteria are typically piloted and then revised. Then the task group members (both OEMs and supplier members) vote to approve or make comments to be addressed.  It is only after this extensive process that the audit criteria are issued as a public document.  Typically, audits cannot occur for at least 90 days for a new checklist after it is issued.  Mandates also take time to be issued by the OEMs. 

Most give a year or more to comply and obtain an accreditation once they issue the mandate letter.  

Although the Nadcap accreditation program for castings appears at least a year or more away for companies supplying the aerospace industry, it behooves foundries to be aware of the Nadcap efforts to impose additional controls on the aerospace casting supply base.

In addition, due to the complexity in the supply chain, it can occur that the aerospace OEMs do not know who the foundry is, and the foundry may not be aware that a given casting is intended for an aerospace application. As such, even foundries who do not consider themselves aerospace should be aware that Nadcap is developing a casting accreditation program.  

Why Nadcap
Quality is the ability to meet or exceed customer requirements and expectations. It can be measured in a number of ways depending on what the customer needs.

In the foundry industry, this could include product quality through various defect measures such as porosity, paint flaws, or surface roughness, and meeting dimensional requirements. Often, such metrics are translated into a defect rate measured in parts per million or ppm. Customers also can have other measures of quality such as meeting on-time delivery requirements, packaging requirements, etc.

However, basic quality has not always been enough. Some processes and components cannot be verified without destructively testing the parts or seeing how they work when in use. The problem is companies cannot destructively test every part and still have parts to use. One also cannot safely rely on trial and error by installing parts and hoping for the best. Therefore, the aerospace industry has developed processes to ensure what has been termed “special processes” are under sufficient control and maintained in compliance. Industry as well as internal company specifications for various processes have been developed. In addition, OEMs have developed process audits to ensure the supply chain is under control and producing quality parts which meet manufacturing requirements.  

This led to suppliers being visited by many companies throughout the year to audit them. This was inefficient, costly and time consuming for both the suppliers and the OEMs.

Overview of Nadcap Process
Nadcap is governed by program document PD1100 that is located along with checklists and procedures on the website www.eAuditNet.com. This document details how Nadcap operates.  This document also details who is eligible to become a Nadcap Subscriber and sit on the Nadcap Management Council (NMC), which establishes the policies and procedures of Nadcap.  It details the responsibilities of the Nadcap task groups which establish various audit criteria to which companies may become accredited.

Once audit criteria are established, the most common reason that companies decide to get Nadcap accreditation is that their direct OEM customers mandate them to do so. Alternatively, depending on where a company is in the supply chain, the mandate may flow down to them via first tier or other layers of the supply chain. Some suppliers will also choose to obtain Nadcap accreditation in the hopes of becoming an aerospace supplier.

Once a company decides to seek Nadcap accreditation, they contact Performance Review Institute (PRI) (PRI) to schedule the audit and get access to eAuditNet.  (Please note that anyone can get access and login to eAuditNet to see public documents including finalized audit criteria.) They will approve the scope of the audit and obtain the audit criteria or checklist in order to prepare. The supplier will then submit a completed self-audit at least 30 days in advance of the audit. This is to facilitate the audit so the supplier knows where various procedural requirements are addressed. It is also to ensure that the supplier is adequately prepared.

Some companies also will schedule a pre-audit prior to the regular audit, which is basically a non-official audit by a consultant auditor indicating all of the areas that are not meeting the checklist requirements.  

In addition to the audit criteria, most task groups have an audit handbook which is also located in eAuditNet. This document indicates clarification and guidance on questions and task group expectations. In some commodities, the task groups have detailed where in a given OEM’s specifications the requirements from the customers can be found that tie to a given question.  

The auditor is the eyes of the task group and conducts the audit to the established audit criteria without providing consulting.  Their role is to decide for each question if it is being met or not.  In rare cases, N/A or not applicable is permitted.  When N/A is allowed is typically spelled out either in the audit criteria itself or in the audit handbook.  If N/A is not indicated on a question then it is not allowed and the question has to be met in the affirmative.

Any questions which are answered negatively result in a nonconformance or NCR. Auditors may group NCRs under criteria that has been established by the Nadcap program. The number of NCRs impacts whether an audit will be balloted to the task group for failure. It also impacts whether an audit may be eligible for merit or the extension of the accreditation period from 12 to either 18 or 24 months. Auditors may at their discretion allow a minor paperwork issue to be fixed during the audit and accept it onsite. Auditors will review the NCRs at the closing meeting. Then after the audit they will upload the NCRs and audit report into eAuditNet.

Unlike ISO 9001 audits, NCRs are not fixed with the auditor unless it is accepted onsite. Once it is submitted into the eAuditNet system, the NCR is addressed with the staff engineers. The staff engineers work directly with the OEM members of the Nadcap task groups so they understand the specification requirements and expectations and the relationship to the audit requirements.  

The staff engineer will work with the supplier to ensure that each NCR has a thorough root cause corrective action analysis conducted to ensure that a recurrence of the issue is unlikely. After the staff engineer is satisfied, they will close the audit and send it to the task group OEM members for review.

The task group OEM members have one week to review the audit.  They can send it back with additional questions or demands on the supplier. Ultimately, the task group is responsible for voting to accredit, fail, and/or issue merit.

If a supplier does not agree with a finding, they can try to persuade the auditor that it is not a finding.  This is most likely to be successful if they provide evidence or clarification to the auditor. Arguing that something is not a customer requirement is not an effective means of getting out of an NCR as the audit criteria effectively becomes the customer requirement.  

In addition, a supplier may ask the staff engineer to void an NCR. The most effective means of doing this is to call or email the staff engineer. Since having more than four cycles of back and forth in the NCR process can result in audit failure, it is unwise to discuss this in the eAuditNet system and waste a cycle.  A supplier can also appeal a finding or even the entire audit to the task group or the NMC Committee on Ethics and Appeals.

Current Nadcap Impact on Foundry Industry
Over 2,800 suppliers are Nadcap-accredited globally. Currently, 19 task groups are shown in Table 1.  Some may apply to foundries currently. That most likely mandates that a foundry may have are heat treating, weld repair of castings, nondestructive testing, materials test labs, or possibly painting.  

Aerospace Quality Systems (AQS) is an accreditation for suppliers who do not have an existing AS9100 accreditation. If they just have ISO 9001 or have no third-party accreditation at all, a supplier has the option of adding a one-day AQS audit to their Nadcap commodity audit. Some suppliers do this to save money from having to do a full AS9100 audit. The AQS audit criteria is based on the AS9100 checklist but is not as extensive since it is only a one-day audit. Thus, some of the OEMs do not accept AQS accreditation in lieu of AS9100.  

Measurement and Inspection is a relatively new task group, and it is possible that the CMM (coordinate measuring machine) audit criteria could apply to foundries.

However, since many castings are subsequently machined, it may not.

Searching the Aerospace QML (Qualified Material List) in eAuditNet for active suppliers with Nadcap accreditations showed around 90 suppliers with either “foundry” or “casting” in their name.  While not all metalcasting facilities have foundry or casting in their name, the majority of existing Nadcap suppliers are not foundries and the majority of foundries do not have Nadcap accreditation.

In 2011, PRI began work on a new audit accreditation program to cover transportation and power generation. Castings were one of the initial commodities to be covered in that program. TPG-AC7127 was originally issued in October 2012.  It is now on Rev B, which was published September 19, 2017.  Currently, there are 28 accredited suppliers.     

Click here to see this story as it appears in the February 2019 issue of Modern Casting