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Author Topic: Commander 500S - Oil Temp  (Read 1789 times)

Russell Legg

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Commander 500S - Oil Temp
« on: October 14, 2015, 11:31:38 pm »
N202JH n202jh@gmail.com via matronics.com
10:06 AM (3 hours ago)

to commander-list
Good Evening,


   My boss has a Commander 500S.

Right engine runs perfect oil pressure in flight. It matches the left engine within one PSI.

However, the right engine does something strange between cold and hot engine core temperatures.

First start of the day, cold engine, you get an initial high oil pressure as expected with cold oil. But it is very high, over 90 PSI. The left engine is only around high 80s.

Right engine oil press comes down as expected after the engine warms.

We take off and in cruise, both pressures are matched +/- 1 PSI.

After landing, the right engine oil pressure is very low, below bottom redline.

If I were to do a feather check at this point, the prop recovery time is very long confirming low oil pressure.

My mechanic replaced the ball and spring for the "oil pressure maintaining valve", if that term is correct, and honed out a fresh seat for the ball.

No change to the oil pressure behavior I listed above,


Any ideas?

Regards,

Derek Groves
Midas Air Corp
Groves Aviation Inc.
Dgroves484@gmail.com
(954) 240-1383

Derek Groves
Midas Air Corp
Groves Aviation Inc.
N202JH@gmail.com
(954) 240-1383

Sent from my iPad


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William Boelte n55bz@cox.net via matronics.com
11:27 AM (2 hours ago)

to commander-list
I believe that there are springs with different rates available for the oil pressure regulator assembly. They are painted different colors- white, yellow and green, if I remember correctly. Washers are placed into the oil pressure regulator on top of the spring to set the minimum oil pressure and the different springs are used to set the max. The condition of the steel ball and the ball seat is critical- just a little surface rust on the ball or a minute scratch on the seat can result in very low oil pressure.

When changing any components of the oil pressure regulator be careful to remove all of the washers inside the spring housings before the initial start.  I did not do this on one occasion and after replacing the ball and refacing the seat blew out the oil cooler about the time that the oil pressure needle reached the end of the scale. It was amazing how rapidly the oil pressure rose.

I believe that there are adjustable oil pressure regulators which do not use washers to adjust the pressure.

Kindest regards,


Bill


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N202JH n202jh@gmail.com via matronics.com
11:53 AM (1 hour ago)

to BillLeff1, commander-list
Hi Bill nice to speak to you again,

The temps are close to even on both...the low pressure side may be a bit higher but I believe that is a result of the low oil pressure situation.  Low oil pressure can bring high temps too I believe.

In cruise, all temps and pressures match each other rather close.


Regards,

Derek Groves
Midas Air Corp
Groves Aviation Inc.
N202JH@gmail.com
(954) 240-1383

Sent from my iPad

On Oct 14, 2015, at 9:04 PM, BillLeff1 <BillLeff1@aol.com> wrote:

What is the oil temp when the pressure is low. How does it compare to the other engine. Also, is the CHT high on that engine? Any metal in the screen or filter?

Bill Leff



Sent from my Verizon Wireless 4G LTE DROID
Good Evening,


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