Hye there, we are in progress to settle down on the defect "No 4 eng RPM overspeed 105%-106% and maintain in normal and mech gov"- During EGR found No.4 TORQUE, TIT and FUEL FLOW, LOW at crossover with RPM overshoot to 104%.INDICATION AT CROSSOVER.Torque : 1400lbs TIT: 678℃ Fuel Flow : 990RECTIFICATION BEING TAKEN :-RPM adjustment.-Blade angle adjustment.-Null orifice + wormshaft adjustment-ectm-valve housing replaced.-syncrophaser- Coordinator resistance cx- tachogene resistance cx- Dome Assembly-SATIS.Still persist after a week : -Propeller and Valve Housing replaced.- SATIS.Still persist on next day :.No.4 engine RPM overshoot to 103.3% RPM on power advance with pitch lock symptomps.+ RPM fuel governed out of limit.- pitch lock regulator - still persist.- FCU replace - SATIS.New snag after a week :No 4 engine nil low pitch stop.- Rigging blade angle and low pitch stop adjustment.-Valve housing adjustment.- Replace dome assy.- Replaced low pitch stop packing.*Still Persist.No 4 eng RPM overspeed with TORQUE, TIT and FUEL FLOW, LOW at crossover with RPM overshoot to 104%.- Replaced Back previous dome assy + low pitch stop packing.* SATIS but torque anticipation very slow during advance throttle.*Throttle already at FLIGHT IDLE, TQ remain : 1.40 lbs.-After about 10 sec TQ increase to 3.4lbs.*Advance throttle, RPM+FUEL FLOW + TIT increase with low TQ until RPM overshoot until 104.4%.- Retard throttle, RPM drop and TQ can SLOWLY can achieved 7.5lbs.-Replaced Coordinator.* Still persist.- Replace another Valve Housing.*Still persist.
Anyone got idea on this synthom ?