"Hot 5 assumtion"

[Diesel]

Just at recurrent.

437 window failures in king airs
Windshield has thermostat that won't let it heat up too much even if it's on the ramp in summer. 107 comes to mind

Gotta run. I've got thoughts on the windshield issue.

 

[prpjt]

I was thinking 105 on the ws thermostat. I'm probably wrong though. I have some feelings on the windsheild issues too. At recurrent did they happen to have any stats on the altitudes where most of the 437 gave out?

I'd be interested in hearing your thoughts on the issue.

 

[b82rez]

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...

Sorry...not ice

http://sportsillustrated.cnn.com/2006/basketball/nba/wires/02/07/2030.ap.bkn.bucks.plane.1st.ld.writethru.0268/

 

[Diesel]

I allways thought keeping the heat on would keep away the birds because they can feel the electricity coming at them. At least thats what I think.

Yeah it's either 105 or 107 they had a nice shattered windshield there that you could take apart. Really explained why it's better to have the heat on takeoff so that it gives it time to heat up. With the heat on the two panes are able to stay the same size and not shrink up which is what causes stress because the outer pane shrinks while the inner pane stays somewhat warm.

Our older windows distort like crazy but I keep the heat on from takeoff to landing because of moisture, windshield life, and flexibility.

They didn't give any stats just that the numbers where replacements not blowouts. I don't think there have been any blowouts of the main windshield just the sides and a couple of them in the back which the AD was issued for.

 

[avbug]

Ad AD was issued, primarily for the 1900's, I believe, for fires and overheats in the windshield heat control.

 

[satpak77]

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.

I am sure P.M. taught you about wind-shield heat, no?

:laugh:

 

[prpjt]

Good stuff Diesel. Another thing to consider without heat is the uneven heating of the individual panel, not just between the inner and the outer.

This was pointed out to me years ago on a flight at 280, and I failed to turn on the heat. The bottom right quadrant of the pilot windshield, and the bottom left quadrant of the copilot’s developed frost on the inner pane.
There was a tiny bit of defrost air coming out but most was directed elsewhere.

What this extreme example told me was that the bottom corner of the inner panel was very cold soaked and the top half of that panel was pretty warm. Now we have the bottom corner contracting and the top of the panel expanding. All of this movement on a piece of glass held in a metal frame. I would think the same variation would be happening to the outer panel, but not at the same rate.

This was an extreme example and was visually apparent. But the same thing is going on to a lesser degree at lower altitudes without heat.. We do a lot of short (18-20 minute) flights and don’t generally use heat on those. There just isn’t much temperature variation at 7000 feet. But on longer higher ones we do. I like the idea of on at takeoff and off at landing but the distortion drives me absolutely nuts.

On the AD, there is or was one on the F90 and 200’s for the D window and cabin windows. The D window one was any windows that were cast acrylic needed to be changed to stretched acrylic. The fuselage one was that the windows had to be multi ply. That’s a real old one (20+ years) and may not exist anymore, but I think the D window one is still in effect. Not sure on the other 90 series

 

[421Driver]

I My theory is that if you decide to put any anti/de-icing devices on is that it is all or nothing. If you are concerned about ice on the pitot, fuel vent, or stall warning you should also be concerned about props and the winshield.

By that logic you'd leace the ice vanes open 100% of the time.

I do what most others appear to. L/R Pitot/Fuel and stall warning. WS heat on at TO if I anticipate ice on ANY segment of the flight (only time I don't turn it on is if it's CAVU on a short flight). Props as needed, ice vanes the same.

 

[Flying Illini]

Hot 5 for us: L & R pitot heat, L & R fuel vents, and Stall Warn.

We STOPPED using windshield heat all the time when we had two windshields destroy themselves. Both on the same day...same crew, same passengers. First flight the right seat windshield shattered (exterior held)...return to base. Then in the second king air, about 40 minutes later, the left windshield shattered (exterior held)...return to base.

We now only use windshield heat when it's needed.

 

[421Driver]

Our KA's had a similar problem to FI's with inner panes going on the right side, two in two months. IMO, it makes more sense to keep a WS a constant temp, rather than rapidly heating a cold soaked screen and risking uneven heating. I've heard different things from different operators, and I used to switch on WS heat as needed, but I just don't like the idea of a screen at -10C being immediately heated to operating temp.