ARTICLE REF – ART224
If you are installing a new or overhauled Gas Generator and you are having issues regulating the oil pressure – this will be of interest to you. The drawing below is the Oil System of the FT8 Gas Generator. The Red dotted line indicated is the limit of the Accessory Drive Gearbox. Inside there is an Oil Pressure Regulator. This regulator was used when the FT8 Gas Generator was used on aircraft. It was called a Pratt & Whitney JT8D turbine. This regulator is still in place but is no longer used when the turbine is installed at your site.
However it is still used in the Test Cell, and sometimes the guys in the Test Cell forget to defeat this adjustment before shipping the turbine. Then when you install the turbine you experience difficulty adjusting the pressure. Sometimes the internal pressure regulator and the external regulator interfere with each other making the pressure unstable and sometimes you just can’t increase the pressure to where you want it to be.
This is a view of the front of the Accessory Drive Gearbox. You can see part of the regulator sticking out the bottom of the gearbox.
Below left youi can see the adjustment screw and lock nut. Access to this adjustment is difficult when the turbine is installed. But it is easy when the turbine is on the crane before installation. So check it before installing the turbine.
Loosen the locknut and turn the screw “FULLY CLOCKWISE” for maximum pressure. Then tighten the locknut again.
End of article