C525 windshield bleed air

[CirrusF]

Simple question - on the CJ series, is windshield bleed air fed to the inside or outside (or both) of the windshield? I can't find a definitive answer anywhere in the Flight Safety blah. At one point the manual says that interior noise increases when bleed air is used (suggesting nozzles are on the inside) and at another point it says that pulling the rain deflector vanes will be more difficult if speed is above 175kts, and windshield bleed air is in use - suggesting that the nozzles are outside. I've also asked several experienced pilots on the type and get any one of all three answers...

[Cecco]

The bleed air is fed only to the outside of the windshield.

Cheers
Cecco

[His dudeness]

Cecco is right. Regurlarly the Bleed air comes from the panels that are mounted on top of the nose. Rain doors are on the outside of these.
Noise can be heard quite well inside and most of the time the effect is questionable.

[orion1210]

Hi,

I'm a type rated engineer on the 525 series.

The nozzles are located in the shrouds located externally at the bottom of the wind shields. The noise stems from the relative high flow bleed air traveling down the right side underfloor, though the fwd cockpit floor and then through the fwd press bulkhead, through the manual valves then finally up to the nozzles.

As the 'rain doors' are physically pulled out into the airflow the airspeed will have a direct influence on the force required to operate. I guess the extra required when operating with windshield air on stems from a possible suction effect, but not sure on that one!!

The defog position on the cabin a/c system just forces the compressor on and diverts the fwd fan air through a heath robinson heat exchanger, to reduce condensation, and then onto the interior of the windshields. This is purely cabin recirc air.

Hope this helps

[Cecco]

Good to have a C525 engineer on this thread. One question to you orion1210:
in our CJ1+ cabin, it is often too cold for our PAX despite having the temperature select knob fully to the right. What I do then is to turn the temp.select knob to the left on manual and to hold up the manual switch up to "hot" for 15-20 seconds; thereafter I rotate the temp.select knob back to the right on hot. Air Conditioning switch is usually on "Auto"; Cockpit Air Dist. knob on 11 o'clock position during climb and on 1 o'clock position for cruise, descent.
Sometimes it gets warmer in the cabin, sometimes not. Any recommendation how you would handle the freezing cabin?

Thanks,
Cecco

[McDoo]

..and while we're there, why is it that when you select the defog fan on at TOD and descend to and airfield with moderate humidity, the bloody screen fogs up on the outside making it difficult to see where the hell you're going taxying in? Am I doing something wrong? I'm only following the Cessna checklist:ugh:

[orion1210]

I don't know about condensation on the outside but the way I get round it is CAUTIOUSLY cycling the w/shield bleed air (IN LOW) to disperse any moisture. Be careful as any long applications on the deck will result in a windshield cx due melting and possibly a p45!?!

As for cabin/cockpit heating problems each aircraft seems to have its own personality. If your able to get the cabin heated in manual mode that proves the RAM air modulating valve is ok so you need to get your maint to look at the auto system. If your warm enough in the front turn the distribution knob all the way from CKPT, think a/clockwise, as this will give more 'hot' inflow air to the cabin.

I once had a 525a come off the 3year id10 with a bleed valve sticking closed and the other in low flow, as norm in BOTH , just enough inflow to maintain max diff but a nearly freezing cabin enroute. Ironically on the ferry flight back we lost the primary door seal at fl410!! Fortunately as I'd got my head around the problem on the deck prior to departure we had RH source selected which elec commands the rh valve to high thus plenty of heat and more importantly in this case no press loss. Back at base the orig snag had gone and has been fine ever since.
My point is if the jets been sat a while cycle the valves a few times with the engs started and at power if your ears can stand it to blow the 'cobwebs' out. I always go down this route if get reports of a cold cabin/cockpit after checking ram air valve ops in manual.