----- Original Message -----
Sent: Sunday, March 02, 2008 9:46
PM
Subject: [LML] Oil Cooler IO-550
Legacy
I recently posted a photo of the cracked oil cooler box on my IO-550
Legacy. The reason I had the box out was that I was adding the oil
cooler door. Like Douglas, I did not install the oil cooler door when I
built my Legacy. First flight was a year ago and my oil temperatures
were fine during the summer, but with winter weather, the oil was too
cool. On a recent flight the oil was down to 130°F. Since I
was doing my first annual inspection, I figured it was the right time to
install the oil cooler door.
That involved removing the oil cooler box, which I needed to do anyway
because of the crack, adding a piano hinge and the door, and installing the
control cable in the cockpit. I work pretty slowly and spent the better
part of two days doing this.
By the way, the TCM shop manual for the IO-550 specifies 170°F as the
minimum oil temperature for cruise. I don't know, but I think
that is based on heating the oil enough to drive off water, which enters the
oil as a product of the combustion process, and not on anything related
to the lubricating property of the oil. (TCM specifies that you can run
100% power with oil temperature of only 100°F on takeoff, so 100°F oil
must provide adequate lubrication.)
Dennis Johnson
Legacy, just completed first annual inspection