"Hot 5 assumtion"

[FN FAL]

I'm gonna take a WAG at this one. Since electrical heaters usually draw more juice than just about everything else, the designers wanted to give a pilot the ability to selectively load shed. If necessary a pilot could cut electric demand almost in half and still have one operating pitot static system and one vented fuel tank to draw from while crossfeeding from it if necessary.

Look at your buss, it's probably bussed seperately as well. No sense in losing it all, when half of it bites the dust.

Is the king air set up so that one fuel vent feeds the whole system as a redundancy? If not, at least the two separate fuel vent heats allow you the option of cross feeding the fuel tanks to the side where you still have fuel vent heat if that ever became an issue.

 

[minitour]

Is the king air set up so that one fuel vent feeds the whole system as a redundancy? If not, at least the two separate fuel vent heats allow you the option of cross feeding the fuel tanks to the side where you still have fuel vent heat if that ever became an issue.

If there wasn't a "cross vent" (like in the 172s...a vent from one tank to the other), when you went to crossfeed from the tank with the blocked vent, wouldn't the vacuum prevent the pump from sucking the fuel out of the blocked tank?

-mini

 

[asolo]

In the summer (CAVU), I don't turn on any heat items till 10K. I leave them on until decending through 10K. During the winter (even during CAVU), I turn everything on when I get cleared for T/O. I turn them off when I get off the runway or if when decending, I note that it is ~+10 C or above and there isn't a temp inversion.

 

[FN FAL]

If there wasn't a "cross vent" (like in the 172s...a vent from one tank to the other), when you went to crossfeed from the tank with the blocked vent, wouldn't the vacuum prevent the pump from sucking the fuel out of the blocked tank?

-mini

Why would you cross feed FROM the blocked tank?

 

[flint4xx]

There is a difference between a technique and a procedure. The before takeoff section of the POH says "Anti Icing-As Required". Saying "hot 5" and turning on whatever you want is a technique, and maybe be a good one at times. I've seen enough techniques turn into "procedure" without any real thought going into it. And there is always the "that's the way we've always done it" mentality that may factor into this. If you default to the POH, "as required" notation, then just do what is right for that flight. I wouldn't turn on any of it for a local flight around pattern in Cancun for example.

Personally, I wouldn't use window heat unless it was required for visibility. it provides no impact protection, and will only cause premature wear and tear. There are over 6000 KingAirs out there, and every now and then a windshield fails just like every other component. You would see an AD to use window heat if that was a real problem in the fleet.

 

[avbug]

I'd have to go back and look, but I believe your stall and pitot heat on those airplanes are hot battery bus items, and therefore require their own switch.

Yes, you can cause damage by applying heat on the ground, not to mention hurting someone who inadvertantly grabs a heated probe.

 

[prpjt]

Originally Posted by TrafficInSight
I'm curious as to why the left/right pitot and fuel vent heats are even separate, is it a load shedding thing?
It’s so the failure of one switch doesn’t kill both sides, a redundancy thing.

Originally Posted by FN FAL
Is the king air set up so that one fuel vent feeds the whole system as a redundancy? The fuel system redundancy on the 200 comes from having 4 fuel vents, 2 on each wing. You have 1 heated tube and 1 recessed scoop vent on each wing. The recessed vent would be very difficult to ice up.
I think the system is similar on the 90B but with an unheated naca vent and a heated tube.

Originally Posted by avbug
“I'd have to go back and look, but I believe your stall and pitot heat on those airplanes are hot battery bus items, and therefore require their own switch.”
On the very early model 90’s I think you’re right, the ones that had the electric inlet heat. On the 200’s they are on the 1 and 2 dual fed busses respectively. On the 90B they were on the either the L and R gen busses or the triple fed.

For windshield and props I’m a use it if I need it type. I do turn on the pitot heat , stall and fuel vent heats. There is no other reason for me other than habit, and I want that habit. Windshield is as required for the flight.
The fuel heat isn’t huge because of redundancy. The stall heat isn’t huge because it doesn’t really work if you have ice around it, but I want to make absolutely sure I have the pitots heated. I’d prefer not to have to remember that one if things got busy.

 

[minitour]

Why would you cross feed FROM the blocked tank?

Beats the hell outa me...that's why I'm asking the dumb questions.

-mini

 

[FN FAL]

Beats the hell outa me...that's why I'm asking the dumb questions.

-mini

I hear ya, the guy who posted above answered mine...makes sense to me.

Speaking of ice, this just hit the news. Kind of reminiscent of that Spirit incident a few years back...

Milwaukee Bucks' plane makes unscheduled stop in Michigan
GRAND RAPIDS, Mich. (AP) -- A Midwest Airlines jet carrying the Milwaukee Bucks and other passengers made an unscheduled stop at Gerald R. Ford International Airport after ice developed in one of its two engines while flying at 20,000 feet, an airport spokesman said Tuesday.

The airplane, which was carrying 74 people, landed at 11:50 p.m. EST Monday, Bruce Schedlbauer said.

The passengers eventually were loaded onto another aircraft and continued their flight to Milwaukee, departing around 2:30 a.m. Tuesday.

Schedlbauer said the engine sustained damage, but he described the landing as precautionary, rather than emergency.


The Bucks were flying out of Cleveland after losing 89-86 to the Cavaliers.

 

[NorthShore]

I agree with Satpak. All of the army C-12 pilots I've flown with say "Hot five" and mean the pitot, stall, and fuel vent. As a unit, we turn on the windshield at 10k, unless needed earlier. In the civilian 300 I fly, we say "Hot six" and this includes the probe heat. I asked our mechanic about it and he said because the probe heat gets hot enough without airflow it could be damaged. I asked the same question of the army contract maintainers and they said it doesn't get hot enough on the ground to worry about. It's never failed.

Our C-12 and the civ. 300 I fly have had a total of 4 windshield replacements in the last 4 years. We were told there was a rash of failures of King Air windshields from PPG from certain manufacture dates.

For what it's worth.

Thats the way we always did it. Did have one W/S failure, but that was at a pretty high temp (VCV, parked for 2 days outside in the summer, ouch!!).