Full power use on T/charged engines

[WX Man]

I operate a PA31-350T. We routinely take off ax MAUW, and therefore use full power on take off, which equates to about 46" MP.

I have recently been advised by another pilot that although this is within the limits of the 49" MP dictated by Lycoming, operating the turbochargers at full whack can damage the engines, possibly leading to an engine failure at some point in the future.

Any thoughts?

[barit1]

I don't think running at rated power (M.P. & RPM) is going to be an issue - but whenever one can reduce the TIME AT POWER it's generally beneficial to engine life.

Bearing loads are dependent on using the correct RPM for each MP - my old boss told me of an R-1820 operator who liked to take off at rated RPM but reduced MP - and his master rod bearing life suffered as a result.

Individual engine models have their own quirks, though, and staying with the builder's recommendation is the best advice.

[WX Man]

Interesting. Regarding correct RPM for the MP, the POH obviously gives correct settings for max endurance, max range etc etc. Where can I find Lycoming's take on this?

[heated ice detector]

From memory You adjust your max MP with a graph relating to Turbo inlet temp.
Its been a few years since I have touched a chieftan but in the tropics ie temp +30 degrees the max MP was always arround 42" on average,
Hope that doesn't confuse the matter.

[WX Man]

Max MP on the left engine appears to be about 42, on the right 46....

I think using full power on take off is OK, it's well within the 49" limit.