B737-300. How can you tell if the Rudder Pressure Reducer plays up?

[Centaurus]

Question on the Boeing 737-300. With regard to the rudder pressure reducer (RPR). Hydraulic pressure to the rudder is limited when the aircraft climbs above 1000 ft AGL and is restored to normal when the aircraft descends through 700 ft AGL - among other things stated in the FCOM.

If due to a defect the hydraulic pressure to the rudder does not return to normal pressure on approaching to land (ie below 700 ft AGL) what cockpit indication would the crew see? Am unable to find the answer in the FCOM or QRH -or maybe I am blind:ugh:

[de facto]

The pressuce reducer is using a modulating valve to reduce hydr pressure to a valve before it enters the rudder actuator.Less hydr press less force on the rudder.
The hydr pressure sensor modules are in the wheel whell ,BEFORE the modulating valve to the rudder actuator.
So i would say there is no info if it is working or not.

[IFixPlanes]

B737 Flight Manual:
Sec. 6.9
YAW CONTROL
Rudder Pressure Reducer (RPR)
...
The DYDC interfaces with both radio altimeters to activate and deactivate the RPR solenoid. On takeoff after reaching 1000’ RA, system A hydraulic pressure to the rudder is reduced to 1000 psi. During approach at 700’ RA, system A pressure to the rudder returns to 3000 psi. If the RPR does NOT change system A pressure to normal at 700’ RA the system A FLIGHT CONTROL LOW PRESSURE light will illuminate; the standby hydraulic system will activate; the standby rudder shutoff valve will open; and the standby rudder PCU is pressurized.
...

[BOAC]

Cent - my manual is a bit different to Ifix. It describes an RPR on sys A and an RPL on sys B. I think to achieve your scenario you would need a double failure of both RPR and RPL to return to 'normal' at 700', or the Force monitor would operate - which is an unlikely scenario, as I read it .

Failure of either to activate would indeed bring on the Flt CTRL light AND the STDBY RUD ON light with Master Caution..

[de facto]

:mad: i was thinking of hydr pressure indicator,to see if there is any change.
Stby rudder light obviously.

[Centaurus]

Thanks for the info chaps. Much appreciated.