First, he still says he wouldn't run
over 210F. I was of course hoping that he's say it was OK to run
more.
I would not suggest running routinely
over about 210, but I’d see no great worries for short durations over
that. It is not the lubrication or the lubricant that we are concerned
about – it’s the side seal o-rings. Running over 210-220
consistently will speed loss of seal. At least that’s the consensus
that I’ve pulled together.
Next, I was asking about how the oil
pressure regulator worked, and got an education. While this may not be
news to some of you, others will find it as disturbing as I do. The
engine has two oil regulators. In my case, the normal regulator is set at
about 75 psi, and is at the inlet of the oil to the engine. The other
regulator is in the front cover, to regulate oil outlet pressure, and is fixed
at 157 psi!!! This is to allow for restriction in the oil coolers and
long lines. He said you'll see this when cold, and likely during that
first climbout, but he didn't believe it would stay that high all the
time. He did think it would always be over 100 psi though.
The ‘regulator’ in the front
cover is not so much regulator as it is emergency bypass at the pump outlet.
This means that the pressure will never go above 157 psi at the outlet because
it is bypassed back to the pan. I don’t know about your evaporator
coolers, but it is very unlikely that you would ever see more than 10-20 psi
drop in the rest of your loop, including the filter. And I don’t
think you are ever going to start your takeoff roll when the oil temp is less
than about 140F, at which point it is very fluid – unless you are using
60 weight gear oil J.
I have 100 psi regulator for the “normal”
regulator, -10 lines with cooler and filters (dual in parallel) and I am not very
concerned. (hum-m-m; does that help any?) I’d say with your 75 psi
regulator you can relax. Just don’t start up on a 20F day and
immediately rev to 6000.
>>>Didn't a rotary airplane
have two (count 'em) engine fires because of burst aftermarket oil
coolers. If memory serves the owners wife made him sell the rotary and
install a Lycoming. <<<
This is a guy that had three coolers in
series, two of which where in the nose (engine in back) with long runs of -6
line and many fittings. Also had a 100 psi regulator. You can bet that
pressure to the first cooler; the one that ruptured twice, was always at the
relief pressure of 157 psi. Add to that some unsupported heavy flex line
to the connector on the cooler tank (can you say “fatigue failure”),
and you have a prescription for a bad day. I had cautioned him twice
about the poor flow path and high pressures; but to no avail. He is just
completing the installaton of a turbocharged IO360 that he rebuilt himself.
He had it run up on a test stand for break-in and it runs well, and he expects
to be flying soon.
Al