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I'm looking to do a N1 low idle speed adjustment oa King Air B350 with the PT6A-60A engine. There is a note saying that one flat movement of the low idle speed screw in the FCU increases N1 by 3.5%

What is "one flat movement" in this context?

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    $\begingroup$ Welcome to the site! Which aircraft are you asking about, and do you have a picture or exact quote of the note? $\endgroup$ – Pondlife May 12 '16 at 20:41
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    $\begingroup$ I'm not a mechanic, but I'm guessing that it means that you are turning the adjustment screw with a flat headed screwdriver, in which case it would be 180 degrees (turning the "flat" part over). $\endgroup$ – Lnafziger May 12 '16 at 20:48
  • $\begingroup$ The aircraft is king air b350 engine pt6a-60a there are 2 screw in one line request to loosen one screw and tighten the other to increase or decrease the n1 $\endgroup$ – mostafa abdelsalam May 12 '16 at 20:57
  • $\begingroup$ The note mentioned that the one flat movement of the screw increasing the n1 by 3.5% $\endgroup$ – mostafa abdelsalam May 12 '16 at 20:59
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    $\begingroup$ Consider a nut or a bolt with a hexagonal shape. It has six flats in three parallel pairs. Turning one of these nuts or bolts by one flat would thus refer to turning it by one-sixth of a complete rotation, ie by 60 degrees. Other nuts and bolts, also some screws, may have other numbers of flats. A Wikipedia page has dimensions across the flats. $\endgroup$ – AdrianHHH May 13 '16 at 11:50

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