Continental TSIO-520-R Fuel Flow questions

[nico87]

Hello,

In the Turbo Centurion checklist, the recommended climb power settings are:

• 30 MAP
• 2500RPM
• FF Lean to 120lbs/hr

On a side note, I see that on hot weather the FF may not reach 120lbs/hr with a full rich mixture, therefore you have to turn on the fuel pump to increase FF, then lean to 120lbs/hr.
Why is the temperature affecting FF in this case?

I know that TCM continuous flow system simply delivers a certain amount of fuel given the throttle position. No MAP or other parameters are taken into account.

Is it correct to state that with a TSIO-520-R, the FF will stay constant during a climb and no mixture change is virtually needed with altitude change (given the same MAP/RPM settings) since the turbo will keep the air pressure constant throughout the climb?

Thanks! :-)

[340drvr]

It's been a few years since I was flying a turbo 210 (or a C340, essentially the same engine x2), but, offhand, 120lbs/hr seems too lean for climb, though maybe not for 30". In general, you're right, the mixture should not have to be adjusted during climb. Temperature-wise, I do recall having to have the mechanics tweak fuel flow with seasonal temperature change, as in, winter setting would not be just right once warmer summer temps came on, and vice-versa.
I believe the entire setup procedure is in this (very extensive!) service directive from Continental, SID 97-3G. A google search will turn up pdf files for this bulletin.
Not sure any of this will help, as I said, it's been a few years for me.

[nico87]

Thanks! Your answer is really appreciated and it shed some lights on my questions.

[dirkdj]

You should watch the CHTs during climb. If they remain constant, your fuel flow is good, if they rise, you need more FF.