PT6A-27 Surging Question
 

With reference to a -27 bolted to a Twoters wing, what would be the likely cause for a werriod TQ indication? When the Power leaver is retarded from 40lbs to aprpox 20lbs (position of power leaver from prior experence on particular machine), the TQ indication will sharply reduce to about 15 lbs, and steeply increase to 25lbs before settleing on 20lbs. It is not being retared particually fast. ?

check the CSU beta interconnect rod to make sure it is rigged properly. I assume this is rigged the same on the 99's. I find sometimes that your problem may be in the prop area and not the power area.