RPM not overshoot during fuel gov switched actuated (Fuel gov and pitch lock cx)

[Farhanz]

Hye guys. Looks like im having some trouble regard my fuel gov and pitch lock cx. The propeller was not overshoot to 103.5% or even more when fuel gov switch been actuated. From that, for sure propeller will not pitch lock. Engine parameters during take off power and fuel gov switch actuated was as below :

TQ : 17K

RPM : 99.6% 

TIT : 1078

FF : 2.2

 

Rectification been carried out as below:

1. FCU worm shaft adjusted (increase almost 6 turns)

2. Synchrophaser replacement 

3. Pitch lock regulator and packing replaced.

4. FCU replaced.

yet, all those thing been carried out. However, the RPM still not overspeeding during actuating fuel gov switch upon fuel gov and pitch lock cx. Please help me my fellows
 

Edited June 28, 2023 by Farhanz

[Lkuest]

If you are at power, actuate the switches, and the RPM does not increase at all and fuel flow does not decrease at all, the problem is in the synchrophasing system. This includes the switches, wiring, and valve housing electrical components. Without the electrical components being good, neither the pitchlock regulator nor the fuel control can cause the issue because they're not given the opportunity to do anything. This also assumes the low pitch stop is adjusted correctly.

[pjvr99]

if there is no RPM increase at all, the signal from the Fuel governing switch is not getting to the valve housing. That is where  you need to start looking .....

[poetryman]

On 7/7/2023 at 9:14 PM, pjvr99 said:

if there is no RPM increase at all, the signal from the Fuel governing switch is not getting to the valve housing. That is where  you need to start looking ..... g

Investigate the wiring between the Fuel governing switch and the valve housing. A potential break or malfunction may disrupt the signal flow. Ensuring a

[niladri]

When contemplating the RPM not overshooting during fuel governor switch activation and pitch lock engagement, individuals might anticipate smooth transitions and stable engine performance. They may rely on precise fuel control mechanisms and pitch lock systems to maintain optimal RPM levels without fluctuations or disruptions.

 

Edited March 26, 2024 by niladri

[Maeve785]

If engaging the switches fails to increase RPM or decrease fuel flow, the culprit likely lies within the synchrophasing system. This encompasses the switches, wiring, and electrical components within the valve housing. Without proper functioning electrical components, neither the pitchlock regulator nor the fuel control can contribute to the issue, as they're not afforded the chance to intervene. Additionally, this assessment assumes the low pitch stop is appropriately calibrated.

[niladri]

The key consideration is ensuring RPM stability when switching between fuel governor and pitch lock actuation. This involves meticulous calibration and synchronization to prevent RPM overshoot, maintaining engine efficiency and safety during transitions, crucial for operational reliability and performance in aerospace and industrial applications.

[sharif101]

At first, test the synchrophaser check, if the check is good change the FCU, if the check fails trouble the synchrophaser system