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Old 13th Nov 2018, 22:34
  #1132 (permalink)  
glad rag
 
Join Date: Aug 2007
Location: London, New York, Paris, Moscow.
Posts: 3,633
Originally Posted by infrequentflyer789 View Post
Based on an old 737 AMM and zero personal hands-on experience, it looks like 737 has something very similar. AMM refers to a "calibrator" which is to used in system performance test after installation. Stall warning system is to be tested with various flap settings rotating the vane until shaker triggers.

I don't have MAX AMM so don't know if that is different - if it is, then that itself could be a source of error (particularly if the difference isn't documented...).

It doesn't look easy to misfit it by 20 degrees (which was apparently the disagreement) - 8 mounting holes (so 45 apart), plus indexing holes. However, there are two compatible parts, one Rosemount one Conrac?, only one calibrator but an adapter is required for one type of vane. Sometimes when things don't fit people use a hammer as an adapter, I can't imagine that on an aoa vane but never say never.

Lots of questions - did they fit it properly, did they test it properly, did the have all the correct test kit, is the MAX different in some way (and did they know), and also, was the sensor replaced more than once (to cause the previous problems as well) with same error made each time.
From my "limited" experience the "pin" locates/datums the unit physically: you then index the sensor to the extremes check output against manual figures thencalibrate using a measuring device degrees to output. On a rotary sensor you use a protractor that is "zeroed" at a specified end stop.On a flapper once again end output checks followed by precise angle/output performance.

Just don't forget to take the kit off for the heater checks....
glad rag is offline