Subject: PSRU seal leaking.
From: Paul
Date: 2/7/1999, 11:22 PM
To: z 

Gary C. Buster LPT wrote:


Paul, I pass this one back to the group... I've never heard of anyone
rotating the Ross PSRU... someone let us know what the results are!!!

  From: Gerry Hess <GVH@yellowknife.com>
  Date: Sunday, January 31, 1999 10:24 AM

  Hi Gary,
  Reading some old saved Rotary NL and saw a email
  where you had solved the Ross PSRU oil leak
  problem. I just started my engine up and I have a
  seal leak. Before I tear it down, have you any
  tips on the solution

   Thanks,
   Gerry



     From: Gary C. Buster LPT <gbuster@ballistic.com>
     Date: Monday, February 01, 1999 9:09 PM

     !!!  Here is a great KEY CONCEPT when routing the plumbing
     for the Ross... start with a good seal, then let the oil
     "slowly flow" through the unit without any gravity putting
     back pressure into the unit... ie: don't run any of the
     plumbing lines above (higher than) the intake or outflow
     ports of the PSRU... even the outflow tube running higher
     than the port will back pressure and pseudo pressurize the
     unit... it does not like to be pressured at all... let me
     say that again... IT DOES NOT LIKE TO BE PRESSURED AT
     ALL!!!!!!!!!  In the past 385 hours of flight, I have gone
     through 2 seals and 2 oil pan rebuilds (thinking the oil pan
     was leaking...)  I actually thought the seals on the ROSS
     were "supposed" to leak with time... once after only 3 hours
     of flight...now I have over 25 hours without a drop... maybe
     I won't have to have an oily engine belly after all!!!

     I am running a 12a bridgeported at 7000 rpm with
     2.85:1, and 4 blade Warp Drive.  I have the Dellorto carb
     and an application specific exhaust system... it looks like
     Tracy Crook's round accumulator, then exhausts through
     another flow through muffler.  I am quite pleased at how the
     Banshee has been quieted... now I can only hear the prop
     noise !!!  I have an Air Command Tandem Gyroplane... two
     seats, 700ish pound empty , 1500 pound gross.  I will be
     replacing the rotor blades after new year's... then I will
     begin testing the flight envelope...



Gary C. Buster LPT




From: Gerry Hess <GVH@yellowknife.com>
Date: Tuesday, February 02, 1999 9:19 AM



Hi Gary,
Thanks for the info. I am wondering if I should rotate the housing as
well. The way Ross has it there are index marks that set the drain
over and up from true bottom. If I rotate it to the next set of two
bolts the drain will be on true bottom. The drain line is connected to
the bottom of the oil pan, and may have been better to connect it
above the level of the oil instead.

Gerry


Should he rotate the housing?

Gerry, build a water manometer and check the pressure in
the Ross housing. The planetary gear set can work as a
pump. Try a tire pressure gauge first to get a feel
for it. If it registers on that you have a real pressure
problem. Also did you check the finish on the seal rubbing
surface? 

I just thought of this. The seal is just behind the helical 
sun gear so it is very important that there be a vent 
path between the seal and the sun gear.

See the drawing below. Try drilling  a small hole in the place
indicated by the arrow to vent the pressure build up, between 
the seal and the sun gear, back to the housing.
If necessary drill the shaft as shown as well.  psru6.gif


Paul Lamar 


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