QnA Responses from Industry Day.pdf

QA-responses from Industry Day

Q&A responses from Industry Day Q: Is there a requirement to list numbers of the gages in the AAIE?

Q clarification: The gages number a contractor assigns to the specific gage

A: Yes. All relevant information on the gage(s) incorporated into the AAIE should be disclosed in the design and test documentation reports to the USG.

Q: Is there a formula or guide for determining guard band?

A: How to establish guard bands is discussed in MIL-A-70625, see paragraphs 4.2.2.2.1.1, 3.4.1 and 6.2 for most AAIEs that take continuous measurements on nonelectronic components (parts). Typically, we want 30 iterations on each variable measurement. IF the data is Gaussian, we want at least a two standard deviation guard band. Please note that I misspoke when I hinted it was 2.5 to 2.8 standard deviations.

If the data is NOT gaussian, we can address that on a case-by-case basis.

We also need to demonstrate what the instrument’s linearity and bias might be. Thus measurements should be taken using parts having a range of well-documented/known dimensions. This data set will help establish the instrument’s linearity and possible bias issues.

Q: Where is in process inspection requirement called out?

A: Requirements for “acceptance by tables” are given in MIL-STD-1916 para 5.2.2. “In-process” inspections are not always required. It really depends on the characteristic and your manufacturing process. Sometimes the requirements can be easily met using incoming inspections (using Attribute or Variable Sampling plans) so there would not necessarily need to be any in-process inspections. When using Continuous Attribute Sampling see paragraph 5.2.2.3, Variable Sampling see paragraph 5.2.2.2, or when doing Attribute sampling (an in-process example might be when doing sub-lots/batches) see paragraph 5.2.2.1.

Mil-STD-1916 is spelled out with lot and/or sublot size; use VL II (verification level 2) for minor and VL IV for major characteristics. 100% sampling, using an AAIE at the designated point of inspection, DPOI, is required on critical characteristics along with VL-VII inspections after the DPOI/AAIE (these are only used to keep tabs on the health of the AAIE).

Get the Code Letter, CL, from Table I and refer to Table II for number of samples to be inspected when doing attribute sampling. For Variable Sampling, see Table I and Table III. Continuous Attribute Sampling see Table I and Table IV.

By the way, there are handbooks available for both MIL-STD-1916 (MIL-HDBK-1916, 10 Feb., 1999, free at quicksearch.dla.mil) and for Measurement System Evaluation, MSE, (Review Guide Measurement System Evaluation Requirements, 2014 Jun 30th, available at ac.ccdc.army.mil/organizations/QESA/, look for it at the bottom of the page).

Q: If we have 3 calipers and they are equivalent to each other but they are different models or brand, do we need to enter all the models on the AAIE?

A: In the MSE you should list them, inform the government of equivalency and then include the manufacturer’s spec sheet and your calibration information on just one of them. The USG is looking for instrument accuracy, NOT resolution, accuracy is what defines equivalency. If the calibration is not performed using the manufacturer’s accuracy limits, the USG will assume the worst case. For example if the caliper is rated +/-0.001” by the manufacturer, but you only calibrate to +/-0.0015”, then you cannot claim any better accuracy than +/-0.0015”. Conversely, if you calibrate to tighter limits, the manufacturer’s spec will typically still be assumed.

Q: Is it acceptable to list standard measurement gages, like calipers and micrometers?

A: This is an MSE answer: No. If you have a number of equivalent calipers (same accuracy) that might be used in your production, we would like you to list them and provide a sample set of documents, including the manufacturer’s specification sheet and the most recent calibration cert, for one of the typical calipers. When it comes to different micrometers, since their abilities can differ significantly, please provide documentation packets on each of them. For other requirements, like test plan submissions, please list the gages and refer the reader to the approved MSE for more information (or simply append your approved MSE to the document).

Q: Where can we find the latest version of the MSE Review Guide?

A: https://ac.ccdc.army.mil/organizations/QESA/ , down at the bottom of page you can download. Recommend quick search on Assist as an additional source for things like DIDs and MIL-STDs/HDBKs.

Q: Where can we find the MSE CDRL?

A: DI-QCIC-81960 is the DID for MSE, contract also has some requirements attached to the AirSpecification (for Air force, reference paragraph “g”). The CDRLs for the contract are on Form DD 1423 and attached to the contract.

Q: Is there anything in particular contractors should add to the MSE to make it easier for the reviewers?

https://ac.ccdc.army.mil/organizations/QESA/

A: Your original format is acceptable (e.g. Excel, Word, or pdfs). Please minimize changes in resubmissions, especially in the document formatting, keep formatting continuous to eliminate our having to rereview already approved portions (because the page changed). Highlight changes made in the resubmission for expedited reviews. A change log is nice but the actual changes on the sheet in the MSE should be highlighted. Address ALL issues brought up in the prior review. Please don’t ignore anything. Sometimes we are just asking a question. Please add some verbiage to answer the question. Sometimes we contest an entry. If we are correct please change the entry. If we are mistaken, please tell us how.