MS1916 AAIE overviews 20241003 Ind Day.pdf

USAF Hill AFB, UT, AFLCMC AFMC/EBH/EBHKC 20240716

OVERVIEW OF DoD & MIL-STD-1916 METHODS OF PRODUCT ACCEPTANCE

For every characteristic in the technical data package (Critical, Major and all the others which are, by definition, Minors, even without 200 series numbers) there are contractual acceptance requirements.

There are a number of options for satisfying those requirements. Three different general options/approaches are discussed below. Feel free to mix and match!

1 MIL-STD-1916 allows using your existing quality control system that meets certain industry standards. This is called “acceptance by contractor proposed provisions.” It typically involves statistical process control, SPC, and continuous improvement techniques.

2 If you don’t want to go with SPC (or anything under #3 below), MIL-STD-1916 also offers a different option called “acceptance by tables.” There are three possible versions of acceptance by tables.

a) Attribute Sampling

b) Variable Sampling, or

c) Continuous Attribute Sampling

a) and b) can be applied to the entire lot or they can be applied to sub-lots, if that is how you prefer to do it. Whichever is more convenient for your manufacturing process. c) is for continuous manufacturing conditions where the component flows right to the next step in the manufacturing process. Of course, it is imperative that the inspection is performed before the characteristic is obscured by a subsequent step in the manufacturing process.

3 The DoD also allows acceptance by other methods, for examples: tool control, Poka-Yoke, or 100% inspection using a piece of automated acceptance inspection equipment, AAIE. AAIE can be a great choice for a continuous manufacturing environment. All these situations must be approved for use by the government. (These approaches are not actually in MIL-STD-1916 but are discussed in MIL-HDBK- 1916 and in the measurement system evaluation, MSE, portion of the contract.) You may also propose some other approach to product acceptance to the USG for consideration.

Each and every characteristic needs to have one of these paths to acceptance. You are free to mix and match paths. For example, you choose to do SPC on (your list of characteristics) but do tool control on these other characteristics (your list) and use AAIE on still other characteristics (your list) but do Variable Sampling on (your list). Pick the path that is best for that characteristic in YOUR manufacturing system.

Your choices should be reflected in your Test Plans, Test Reports, and MSE submissions.

Please note, that the above inspection requirements are completely separate from any other product requirements, especially lot acceptance tests, LATs, and first article tests, FATs. All the components and characteristics created when building for FATs and LATs need to satisfy the acceptance requirements of MIL-STD-1916 and the contract.

The data gathered while performing any of the above acceptance operations is conveniently submitted to the USG appended to the corresponding LAT and/or FAT reports.

This is just a high-level overview. There are many details associated with all of the paths above that were not addressed here. The point is, you have many options from which to choose.

USAF Hill AFB, UT, AFLCMC AFMC/EBH/EBHKC 20240716

OVERVIEW OF AUTOMATED ACCEPTANCE INSPECTION EQUIPMENT AT THE DoD

AAIE is one approved path to product acceptance at the DoD assuming certain conditions are met. The measurement system evaluation, MSE, portion of the contract defines the rules. The data item description, DI-QCIC-81960 para. 3.6.d gives some of the details. It invokes MIL-A-70625A (design, testing and approval of automated acceptance inspection equipment) for more details and requirements. If MSE is not on the contract, we still follow these rules for AAIE approvals.

There are three levels of AAIE design review all requiring USG approval. The design reviews are intended to make sure that the AAIE does, in fact, incorporate all of the required characteristics BEFORE the AAIE is constructed. If you are half way through your designs, please contact the USG ASAP!

1 Fail-safe design is required. The AAIE must automatically assume every component is nonconforming until it is found to be conforming by the equipment. You must establish and reveal your contingencies for power loss, communications failures, disruptions in pneumatic supply, etc.

2 Designed for periodic calibration.

3 Designed for periodic verification, typically known reject master parts need to be fed into the system and it is required that the system does actually reject the parts and that they exit the system into the reject bin. This verification ability should be designed to have minimal impact on your manufacturing process and that may require some serious thought. This verification process is used to assess the continuing efficacy of the AAIE while in production. The verification function has been a stumbling block with past AAIE approvals. Please plan ahead.

4 Decision making, it is highly desirable that the measurement system takes a variable measurement (not a pass/fail at this point) of the characteristic. The actual values obtained need to be compared to the true values of the (well characterized) master parts to demonstrate the sensor’s innate abilities. A test plan must be drafted and USG approved to show that the system has all of the required characteristics before it can be used to perform product acceptance testing.

a) An accuracy test needs to be performed. (See, for example, MIL-A-70625A para. 4.2.2.2.1.1) Typically, this testing will establish the guard bands needed so the AAIE does not accept nonconforming components.

b) USG witnessed decision making reliability test. (See, for example, MIL-A-70625A para.

4.2.2.2.2.1 and the MSE requirements in the contract.) A test to show at xx% Confidence that the AAIE has at least yy% Reliability. Example, if 90% Confidence in 95% Reliability is the contractual requirement, the system must detect and reject at least 45 samples of each defect type without fail. A mix of conforming and nonconforming product should be used in this testing.

c) Final report submitted for USG approval. Once approved, the AAIE may be used for product acceptance purposes. If the AAIE is NOT used for product acceptance purposes (you are inspecting somewhere else) none of these requirements are applicable. No disclosure required.

This is just a high-level overview. There are many details associated with all of the steps above that were not addressed here. The point is, you need to satisfy the AAIE contractual requirements and that may very well affect the design of your system.