Too many bugs in my oil cooler..

[pierre smith]

I learned a valuable lesson recently, when my oil temp in the Air Tractor's PT-6 turbine started over redline! I immediately pulled up out of the field, reduced power and headed the 10 miles home, really worried.

I managed to keep the temp right on redline, which is only 100C and running synthetic oil. We pulled the cowls off and I soaked the big oil cooler with Purple cleaner from behind and had a strong stream of water from the hose and zillions of insects fell on the slab as we rinsed, repeated and rinsed again.

There's big scoop for the cooler inlet and it must act as big insect funnel as well.

The flight thereafter was not without a bit of trepidation, but circling the airport, the temp was now a good 1/4" below redline and I returned to the field and all was well. I later discovered that I have an intermittent gauge/sender as well.

You guys ought to consider back-washing your oil coolers occasionally, as I'm gonna do with the -10. During some full-moon periods, I see an enormous increase in insect populations and I can't help but believe that some of our oil temp problems could simply be a clogged cooler.

Best,

[terrykohler]

Pierre:
Never though of that one. Here in Michigan, we have about 6 months of bug-free flying (9 months if you live in the Upper Peninsula). Of course, what you're doing is a little like an accelerated ASTM test - the front end of your plane probably sees more bugs in a day of spraying than we do in a year. Any chance you can post a picture of your leading edge after a day of battle?
Terry, CFI
RV-9A N323TP

[aerhed]

Pierre,
No problem. Just hire someone else to go over your fields first with Malathion. Then you can go behind them, bug free. How's that for practical?

[rvmills]

Pierre,

Its the bugs fighting back! They know who you are and have seen what you've done to a billion of their relatives!

Good thought though...I've never seen any bugs on my baffle-back-mounted cooler inlet (or the cover I put on it in winter), but there are less bugs up in the high desert. I'll have to look at it after X-Cs and/or races at sea level, where they attack my leading edges with a vengeance! Those with external scoops feeding a cooler directly (like your Tractor) may be more susceptible.

Good info...glad it wasn't something that would slow down your biz flying!!

Cheers,
Bob

[pierre smith]

...at annual/condition inspection, the cowls are off anyway. Maybe that many bugs don't go into the cowls on our RV's but it's a good time to look.

I also get some spray in the oil cooler and it's all contaminants that reduce airflow. The opening is around 4" X 6 1/2":



Best,

[David-aviator]

Good post, Pierre.

Makes me wonder how many bugs my ram air intake is sucking into the fuel injection system? I've been opening it at about 200', maybe it would be better to delay that little power boost a bit.

[pierre smith]

...and zero dirt or bugs are ingested. As you know FOD is always a problem with jets and turbines but Air Tractor has beautifully addressed this problem.

I don't think that ingesting a few bugs will cause any problems....a little protein for the Lyc

Best,