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articles:soot [2025/07/09 18:01] – [What does this mean?] rrandallarticles:soot [2025/07/26 21:48] (current) – [What does this mean?] rrandall
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 **Rule (a):** \\  **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). \\ 
  
-Suppose you're measuring the length of a part that should be exactly 100 mm, and the acceptable error (tolerance) is ±2 mm (meaning the measurement can be between 98 mm and 102 mm). +<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>
  
-2 mm ÷ 4 = 0.5 mm+__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). 
  
-The measurement device was calibrated at 100 mm and found to read 100.6 mm.+25% of the product tolerance - 2 mm ÷ 4 = 0.5 mm (or 2 mm x 0.25 = 0.5 mm). 
 + 
 +__Calibration of Measuring Device__ \\  
 +The measuring device was calibrated at 100.0 mm and found to read (display) 100.6 mm.
  
 This indicates a bias error of +0.6 mm. This indicates a bias error of +0.6 mm.
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 Since 0.6 mm > 0.5 mm, this is more than 25% of the tolerance of the product, so it's a SOOT condition for the measuring device. Since 0.6 mm > 0.5 mm, this is more than 25% of the tolerance of the product, so it's a SOOT condition for the measuring device.
  
 +__Measurements__ \\
 Suppose the product was measured, and the measurement device indicated it was 98.5 mm.  Suppose the product was measured, and the measurement device indicated it was 98.5 mm. 
  
-Since we know that the measurement device is reading with a bias of +0.6 mm, then the measured product "//could//" actually be 97.9 mm... which would be out of tolerance. +Since we know that the measurement device is reading with a bias of +0.6 mm, then the measured value "//could//" actually be 97.9 mm... which would be out of tolerance. 
  
 98.5 mm (reading) - 0.6 mm (the bias) = 97.9 mm (actual measured value) 98.5 mm (reading) - 0.6 mm (the bias) = 97.9 mm (actual measured value)
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 <WRAP center round info 80%> <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> </WRAP>
  
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 **Rule (b):** \\  **Rule (b):** \\ 
 The Measuring and Test Equipment (M&TE) error is greater than twice the calibration tolerance when product tolerance isn't known. \\ 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 up to 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>
  
-Assume that the measurement device was calibrated at 100 mm and found to read 98.9 mm (1.1 mm low).+__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.\\ 
  
-This means that whatever reading your measuring device shows has a +1.1 mm bias (indicating the true measurement is 1.1 mm greater than indicated). +Twice the calibration tolerance = 2 × 0.5 mm = ±1.0 mm \\ 
  
-So if your device shows a measurement that reads as 101.0 mm, it's true reading would be 102.1 mm (101.0 + 1.1 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 measuring device error was found to be greater than twice the calibration tolerance. 
 + 
 +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. \\ 
 + 
 +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. \\  
 + 
 +<wrap em>HOWEVER</wrap>, what if the measuring device was 10 times more accurate than the product tolerance? \\ 
 + 
 +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. 
  
-Since 1.1 mm > 1.0 mm, this is more than twice the calibration tolerance (± 0.5 mm) of the measuring device… and is therefore considered a SOOT condition. 
 ===== Why was this added to their requirements? ===== ===== Why was this added to their requirements? =====
  
 AS9100C (Issued 1999) had included the following requirement: AS9100C (Issued 1999) had included the following requirement:
 <blockquote>//7.6 Control of Monitoring and Measuring Equipment \\  <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 found not to conform to requirements. The organization shall take appropriate action on the equipment and any product
 affected.//</blockquote> 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". 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".