It has been reported that the Woodward 8210 Series Beta valve plunger assembly for a turbine engine propellor governor can accumulate dirt and grit, causing sticking of the plunger. This can cause a condition of remaining in the Beta range when increased power is applied.
Woodward Governors has approved field cleaning of the Beta valve plunger assembly through the issuance of the following text from a Service Letter.
Remove the Beta control arm by removing the pin from the Beta valve plunger and the AN bolt from the control rod. Remove the safety wire and with a 1-1/8″ wrench, break the Beta cap loose. Be cautious removing the nut, because the Beta plunger is spring loaded. Once the nut is removed, allow the Beta plunger assembly to move out to contact the back of the spinner back plate. Leave the nut on the plunger for cleaning.
Using a shop grade Stoddard solvent, MEK, or Acetone, clean the plunger. Blow dry after cleaning, apply turbo oil to spacer and -780 O-ring and reinstall the Beta cap and torque to 450-500 lb./ in. Safety wire the cap and reinstall the beta control arm.
Conduct an operational check of the Beta control and note the responsiveness of going in and out of the Beta range.
The cleaning and inspection of the Beta plunger assembly shall be conducted at each annual inspection. If sluggishness of the Beta control is noted due to operations in dusty conditions, more frequent inspections and cleaning may be required.
All work on the beta valve plunger should be performed by an appropriately qualified person.