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--- articles:soot [2025/07/09 18:31] – [What does this mean?] rrandall
+++ articles:soot [2025/07/26 21:48] (current) – [What does this mean?] rrandall
@@ Line 18: / Line 18: @@
 **Rule (a):** \\
-The Measuring and Test Equipment (M&TE) out-of-tolerance condition exceeds 25% of the product tolerance (the maximum acceptable level of deviation from a product’s specification, measurements or standards).
+The Measuring and Test Equipment (M&TE) out-of-tolerance condition exceeds 25% of the product tolerance (the maximum acceptable level of deviation from a product’s specification, measurements or standards). \\
+<wrap em>This SOOT criteria focuses on the Accuracy Ratio as it relates to the product... without consideration to the accuracy of the measuring device.</wrap>
+__Example:__ \\
 Suppose you're measuring the length of a part that should be 100mm with an acceptable error (tolerance) of ±2 mm (meaning the measurement can be between 98.0 mm and 102.0 mm).
-% of the product tolerance - 2 mm ÷ 4 = 0.5 mm (or 2 mm x 0.25 = 0.5 mm
+% of the product tolerance - 2 mm ÷ 4 = 0.5 mm (or 2 mm x 0.25 = 0.5 mm).
 __Calibration of Measuring Device__ \\
@@ Line 41: / Line 44: @@
 <WRAP center round info 80%>
-In other words, a 4:1 Accuracy Ratio was not maintained between the measuring device and the product being measured.
+In other words, a minimum 4:1 Accuracy Ratio was not maintained between the measuring device and the product being measured.
 </WRAP>
@@ Line 48: / Line 51: @@
 **Rule (b):** \\
 The Measuring and Test Equipment (M&TE) error is greater than twice the calibration tolerance when product tolerance isn't known. \\
-Example: \\
-Keeping with the above example, suppose your measuring device has a calibration tolerance of ±0.5 mm (meaning the device could be off by ±0.5 mm). \\
-Twice the calibration tolerance = 2 × 0.5 mm = 1.0 mm \\
+<wrap em>This SOOT criteria focuses on the Accuracy Ratio as it relates to the measuring device... without consideration to the tolerances associated with the product.</wrap>
+__Example:__ \\
+Keeping with the above example, suppose your measuring device has a calibration tolerance of ±0.5 mm (meaning the device could be off by ±0.5 mm). This provides a 4:1 Accuracy Ratio with the produce tolerance being measured.\\
+Twice the calibration tolerance = 2 × 0.5 mm = ±1.0 mm \\
 __Calibration of Measuring Device__ \\
 Assume that the measuring device was calibrated at 100.0 mm and found to read 98.9 mm (1.1 mm low).
-This means the device underestimates measurements by 1.1 mm (since 100.0 mm - 98.9 mm = 1.1 mm).
+This means the measuring device error was found to be greater than twice the calibration tolerance.
-Bias: -1.1 mm (the device's readings are 1.1 mm less than the actual measurement).
+Conclusion: \\
+This somewhat arbitrary approach toward defining a SOOT condition has little to do with determining the IMPACT of the Out-Of-Tolerance (OOT) condition. \\
-__Measurements__ \\
+If we know the product tolerance, and determine that it had been a 4:1 Accuracy Ration, then halving the calibration accuracy of the measuring device (which is what doubling the error does), means that a ≤2:1 Accuracy Ratio exists. That would indeed be significant. \\
-When taking a measurement, the measuring device reads: 101.0 mm
+<wrap em>HOWEVER</wrap>, what if the measuring device was 10 times more accurate than the product tolerance? \\
-However, the "actual" measured value must include this bias:  **Actual = Displayed Value + Bias**
+In that case, an error of twice the calibration tolerance would have simply reduced the Accuracy Ratio from 10:1 to 5:1. Since an Accuracy Ration would have still been greater than 4:1, the impact would have been insignificant.
-This means: 101.0 mm + 1.1 mm = 102.1 mm
-Conclusion:
-.1 mm > 102 mm, so the part is out of tolerance
-This means that whatever reading your measuring device displays has a -1.1 mm bias (indicating the actual measurement value is +1.1 mm greater than indicated).
-So if your device displays a measurement of 101.0 mm, it's true reading would be 102.1 mm (101.0 + 1.1 mm)! \\
-Since the bias (1.1 mm) this is more than twice the calibration tolerance (± 1.0 mm) this is a SOOT condition.
 ===== Why was this added to their requirements? =====
 AS9100C (Issued 1999) had included the following requirement:
 <blockquote>//7.6 Control of Monitoring and Measuring Equipment \\
-In addition, the organization shall assess and record the validity of the previous measuring results when the equipment is
+In addition, the organization shall assess and __record__ the validity of the previous measuring results when the equipment is
 found not to conform to requirements. The organization shall take appropriate action on the equipment and any product
 affected.//</blockquote>
-After I personally issued a MAJOR nonconformity to a major aerospace company for not following this requirement, this entire paragraph was removed from AS9100D (1999-11). Was this coincidental? I doubt it.
+Under this version of AS9100, while performing an audit on behalf of a Certification Body at a major aerospace company involved with the development of AS9100, I had personally issued a MAJOR nonconformity for __not__ retaining these records. I seriously doubt that it was coincidental that the requirement for retaining these records was eliminated from AS9100:2016 (Rev. D).
+AS90100:2016 (Rev. D) changed this requirement to read: \\
+<blockquote>7.1.5.2 Measurement Traceability \\
+The organization shall determine if the validity of previous measurement results has been adversely affected when
+measuring equipment is found to be unfit for its intended purpose, and shall take appropriate action as necessary.</blockquote>
+This removed the requirement to retain a record of the nonconforming (e.g., Out-Of-Tolerance) condition.
 The removal of this requirements was a step BACKWARD for AS9100... and Collins not only recognized this, they took it a step further by defining the word "significant".