Frozen compass.

[slipstream21]

I did my first manual start-up from the ramp and departed as normal, all good except my compass was frozen- no movement. Any ideas please?

[Kang]

Which compass are you referring to? The gyro in the main instrument panel or the magnetic compass? Are the other instruments working alright? The gyro requires power to the instrument inverter to work.

[slipstream21]

Directly below the HSI. I’m assuming that on the start-up sequence I have missed something.

[WildBillKelsoe]

maybe you had loss of power or touched a circuit breaker by mistake. Its funny you would say tgis because I just finished wavehoppers campaign intro flying at 16,000 ft above a soup and my engine icing warning came to life. Shortly after starting anti icing by pedestal near fuel pump, my speedometer froze to 160 knots and upon descending in a nose down attitude, it turned all the way back to zero knots while I was flying forward in a dive towards base leg, and from thereafter, remained at zero knots. I used my surroundings till I came to hover then set her down nice and gentle.

 

The idea is that it could be electrical system freezing or battery problem.

[Robert31178]

You would know if it was frozen because of a power issue, it would have the little yellow flag in the lower right corner. If you missed the inverter step and turning your AC power on then your compass wouldn't read properly. Once you have your inverter on and AC power to knob set to "AC Phase" then you have to manually align your compass and double check it with your MagCus (magnetic compass).

 

Kelsoe, yours is a different problem, you didn't run your pitot heat. If you leave the switches off for those systems then you may experience icing in both engine and pitot. The engine icing light on the annunciator panel will indicate you are about to experience a loss of power due to icing, and turning the anti-icing switch on will clear it in a minute or so.

 

The same does NOT apply for the pitot heat switch, once it clogs up or freezes up it does not come back until you spawn a new aircraft (this is just my experience so far, anyone else have something different?). Your indication of either a frozen or damaged pitot tube is your indicated airspeed being something other than what you know it ought to be, like in level flight at 32% torque you know you'll be doing around 90kts indicated, so if you are showing 40kts or 130kts in straight and level flight then you know you have a problem.

 

What I do is pretty much coming into fall I get into the habit of running the pitot heat, and I turn it on after I have a green bird on the ramp. Both the pitot heat and anti-icing create huge draws on your system, so unless you are on ground power you stand a good chance to killing your batteries, especially in weather cold enough to warrant the use of both from the get go, i.e., snow on the ground.

 

Hope that helps!

 

`Rob

Edited November 28, 2017 by Robert31178

[slipstream21]

Thanks Robert. All working now, except it’s not calibrated. I fly N but am heading SW. I know how to calibrate, however, I need a N reference. How does one provide a reference for N?

[Kang]

There are two things for that, basically: first, there is the white dot on the top right corner of your course indicator. If you turn it through the magnetic heading, it will change to a white cross instead. You are properly aligned with the dot and the cross both halfway visible. Also, and also to double check your calibration, you have the magnetic compass sort of stuck to the right side of the main instrument panel.