Takeoff power / RPMs

[Bruce Hampton]

I have a 65 PA 30 with the IO320's ( turbo normalized ) based out of KROS. Sweet running airplane and enjoying the heck out of it. I have noticed an oddity I can not explain.

On the RT engine only - I can not generate TAKEOFF power until such time as the engine oil temp is 120 degrees or better. I did notice this last summer, but since OAT was much warmer than here in the winter, it would not pose much of a problem because of the taxi and run up would generate the heat and all was *normal* by the time I was ready to take the runway.

Well here in the winter time, it is a little more pronounced. I have a pair of EI MVP 50's installed and, what I can tell you is that most everything appears to be normal except Fuel Pressure and RPM's. Of course none of this is obvious until such time I am ready to depart. The RPM's will come up to about 2100 for the prop and mag checks just fine. It just won't go to full power, in reviewing the EDM data on Savvy Analysis, it appears to be something that has been going on for some time, and just not as pronounced until now.

Yesterday - I made a ground test run, and set PROP, MIXTURE for take off and made sure FUEL BOOST PUMPS were on. I made it ready for takeoff in other words. I did this while the engine was not up to temp yet ( CHT's were > 200 ), during this test, I did not adjust anything but the power controls. The LT engine is performing as it should so, I have that to compare against as normal. The RT engine comes up to about 2100 RPM, Manifold pressure on both engines is the same. While monitoring the OIL TEMP, I tried 5 times to generate takeoff power. I do have Tannis heaters on this, so OIL TEMP started out at 90 degrees, and subsequent attempts to generate takeoff power were made at oil temps of 100, 105, 110, 115, 120. It wasn't until such time as I hit 119 degrees that I was able to generate full power on the RT engine. The LT engine came up to full power on the first attempt.

Any ideas would be appreciated.

[N3322G]

Hmmm. My Twin is normally aspirated - if we had that problem, I'd be looking at things that the oil runs like the prop. When was the last the prop and/or governor was overhauled?

[Zach Grant L1011jock]

Simple trouble shooting if you don't have a C/R. Swap the rt and left governors. If the problem follows, its the gov. Id bet money it is the gov but depending on shop rate, it might be cheaper to be sure, or just send the gov. in for overhaul. I have flown planes that had this same problem, however they were set to 2700rpm cold, and then would overspeed if hot. Simple enough to pull the prop back but required attention from the pilot. I have to ask, are you sure it is not an indication error? Tachs can be pretty inaccurate. Synched props don't lie however, so if they are synched by sound, or not, then you can rule out instrument error.

-Zach

[Bruce Hampton]

Thanks Zach for the reply. It is most definitely not an indicator problem as there is considerable pull from the LT engine, and when the RT engine does come to life; it evens out nicely. The tach's are also fairly newly installed MVP 50's - so I believe them to be accurate.

I have considered the governors, but have not yet elected to swap them as they are time consuming, mounted in amongst the turbo's and fuel pump.

[Clarence Beintema]

Do your engines have stainless steel oil transfer lines from the prop governor to the front bearing or rubber hoses? If hoses one may have an assembly error causing slow response.

You might also contact Lycoming, I remember vaguely a test of the oil transfer and front bearings.

Clarence