Low torque, high temps

[Tomaz 10]

Hi!

I'm currently flying from TNCM. At 12000ft, 5°C OAT, props at 91%, I can only set 31 of torque without crossing into the red temperatures (T5) which gives me only about 140kts. Is this normal? If I set torque as per charts (42), the engines are gonna blow up. Or am I missing something?

And another thing.. whenever I press IAS on AP the aircraft pitches up heavily. Is this normal?

[Finn 873]

With +5°C at 12.000 ft Your OAT is allready 14°C above standard ISA condition, which would have been ÷9°C.

I miss information about what version (-100 or -300) as well as anti-ice configuration, since that affect You max allowable torque.

Whenever You are in doubt, open the checklist gauge and lok on the config page. Two torque gauges are shown. Whwnever the needles are white and the T5 indicator isn´t red, then Your good to go.

Regarding IAS mode...

The correct way of using it is to establish our self in a steady climb by adjusting elevator trim until Your climbing at a steady speed, then activate IAS.

If You are accellerating, then the aircraft will pitch up inorder to keep the airspeed that was present when IAS was engaged.

Just like in real life teh autopilot of the Twin Otter is exposed to the same aerodynamic forces than if the pilot had to fly it - it´s no wondersystem.

An autopilot is not a pilot replacement, but rather a pilot assistant. It´s performance still relies on the pilots ability to setup conditions that makes it easy for it to control the aircraft..

Finn

[Tomaz 10]

I use type -300, bleeds off, anti-ice off. Yes, I guess it's because high air temperatures. In checklist gauge, the needels were far away from blue line but in the VC in temperatures gauge the needels were just shy from red area.

I guess I was using AP wrong. Thanks for the tips.

[Finn 873]

Just to visualise how OAT, altitude, Airspeed, Anti-ice and Prop RPM affects engine performance, look on this table:

The blue line shows what You expected (not taking ISA deviation into account) and the red line what really happened (± some reading inaccuraceties as well as some in sim simplifications on how the various values affect the calculation of max torque and max T5).

Finn