bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

Window Heat Inoperative?

Mon May 31, 2004 10:31 am

Hi everyone. I just recently saw a 767 overhead panel picture and the window heat was inoperative. My question is, does it belong to the MEL? Which restrictions apply to having window heat inop.? Thanks in advance

-Alfredo
 
dl757md
Posts: 1482
Joined: Mon May 24, 2004 9:32 am

RE: Window Heat Inoperative?

Mon May 31, 2004 10:41 am

Bio15

The 767 window overheat switchlight will show INOP when the switchlight is selected off. The switches are a two position push switch and the INOP light really is an indicator of switch position - off - as well as a fault indicator when the switch is pushed on. If it were a fault it could be dispatched under the MEL depending on weather conditions and which window it was. Don't recall the exact restrictions off the top of my head.3

Dl757md

757 Most beautiful airliner in the sky!
 
greasespot
Posts: 2955
Joined: Sat Apr 24, 2004 10:48 am

RE: Window Heat Inoperative?

Mon May 31, 2004 10:52 am

There is usually a speed restriction at certain levels. Window heat is not just to get rid of frost it also adds to the impact resistance of a window.

GS

oh yeah it is a MEL item
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Window Heat Inoperative?

Mon May 31, 2004 10:58 am

Hi Dl757md, thanks for your response. After reading your response, I came to realize I was looking at a different item on the overhead panel. What I saw was a black INOPERATIVE sticker over the Rain Repellent buttons just beside the wiper switch, and thought they were the window heat buttons. I was fool enough to think I knew what those were, Embarrassment sorry for that one.


That being said, now I'm intrigued, where are the window heat pushbuttons located on the overhead panel? I could not find them by simple inspection.

Thanks again, sorry again.  Smile

-Alfredo
 
airplay
Posts: 3369
Joined: Sat Oct 25, 2003 1:58 am

RE: Window Heat Inoperative?

Mon May 31, 2004 11:00 am

The 767 MEL states:



41-1 Flight Deck
¦ Window Heat
¦ Systems

¦ 1) No. 1 (fwd) C ¦ 2 ¦ 1 ¦ (M)Except for ER operations beyond ¦
¦ Windows ¦ ¦ ¦ 120 minutes, one may be inoperative ¦
¦ ¦ ¦ ¦ provided: ¦
¦ ¦ ¦ ¦ a) Airplane is not ¦
¦ ¦ ¦ ¦ operated in known or ¦
¦ ¦ ¦ ¦ forecast icing conditions, ¦
¦ ¦ ¦ ¦ b) Both No.2 (side) window ¦
¦ ¦ ¦ ¦ heaters operate normally, ¦
¦ ¦ ¦ ¦ c) Associated windshield ¦
¦ ¦ ¦ ¦ pneumatic anti-fog system ¦
¦ ¦ ¦ ¦ operates normally, and ¦
¦ ¦ ¦ ¦ d) Associated window heat is ¦
¦ ¦ ¦ ¦ deactivated. ¦

¦ 2) No. 2 (side) C ¦ 2 ¦ 1 ¦ (M)One may be inoperative provided: ¦
¦ Windows ¦ ¦ ¦ a) Both No.1 (fwd) window ¦
¦ ¦ ¦ ¦ heaters operate normally, ¦
¦ ¦ ¦ ¦ and ¦
¦ ¦ ¦ ¦ b) Associated window heat is ¦
¦ ¦ ¦ ¦ deactivated. ¦

¦ 3) No. 3 (side) C ¦ 2 ¦ 0 ¦ (M)May be inoperative provided ¦
¦ Windows ¦ ¦ ¦ associated window heat is ¦
¦ ¦ ¦ ¦ deactivated. ¦
¦

¦ 41-2 Window Heat INOP C ¦ 4 ¦ 0 ¦ (M)May be inoperative provided ¦
¦ Lights ¦ ¦ ¦ associated window heat system is ¦
¦ ¦ ¦ ¦ verified to operate normally before ¦
¦ ¦ ¦ ¦ each departure. ¦

¦ C ¦ 4 ¦ 1 ¦ May be inoperative provided ¦
¦ ¦ ¦ ¦ associated window heat system ¦
¦ ¦ ¦ ¦ is inoperative.



No speed restriction imposed on this airplane, but it is a common limitation for turboprop airplanes with inoperative window heat for the reasons stated before.
 
dl757md
Posts: 1482
Joined: Mon May 24, 2004 9:32 am

RE: Window Heat Inoperative?

Mon May 31, 2004 11:13 am

Bio15

The rain repellant systems on all Boeing AC were deactivated years ago by Boeing. I'm not sure of the reason. Anyone out there care to enlighten?

Dl757md
757 Most beautiful airliner in the sky!
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Window Heat Inoperative?

Mon May 31, 2004 11:15 am

Thank you Airplay for the information, that is what I was looking for.

---
Greasespot, it's interesting that window heat will add impact resistance to the windows. I would think it adds elasticity to the window thus lessening the chance of shattering. Is this correct?

-Alfredo
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: Window Heat Inoperative?

Mon May 31, 2004 11:23 am

Re: The rain repellant system being deactivated

May or may not be the reason but there was at least one successful lawsuit a while back. Seems that inhaling the fumes caused a pilot "permanent neurological damage" and never mind the "who'd notice" comments.

Happiness is not seeing another trite Ste. Maarten photo all week long.
 
dl757md
Posts: 1482
Joined: Mon May 24, 2004 9:32 am

RE: Window Heat Inoperative?

Mon May 31, 2004 3:46 pm

Bio15

Greasespot, it's interesting that window heat will add impact resistance to the windows. I would think it adds elasticity to the window thus lessening the chance of shattering. Is this correct?

It is absolutely correct. BTW great posts Greasespot, Airplay, and SlamClick. Big grin I think we put this one to bed.

Dl757md
757 Most beautiful airliner in the sky!
 
CX Flyboy
Posts: 6039
Joined: Sun Dec 26, 1999 6:10 pm

RE: Window Heat Inoperative?

Mon May 31, 2004 11:12 pm

One of our 777s a few months ago started having an arcing window in the cruise on the way to manila. The crew switched the window heat off and the window in question cracked during the descent resulting in a huge delay waiting for a new window to be flown up from Kuala Lumpur at huge cost. Not sure how it's related to your question, but it's interesting nonetheless!
 
MD11Engineer
Posts: 13916
Joined: Sun Oct 26, 2003 5:25 am

RE: Window Heat Inoperative?

Tue Jun 01, 2004 3:48 pm

Often enough a window heat problem iscaused by the temperature sensor imbededin the window pane (the small zig zag line ofwires close to an edge). Many modern airplanes have a spare sensor in the window, so depending on which A/C type, one just reconnects a plug or switches over to the spare sensor. BTW the voltages and currents used by the windshield heat system are lethal! Always pull the C/B!

Jan
Je Suis Charlie et je suis Ahmet aussi
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Window Heat Inoperative?

Tue Jun 01, 2004 11:55 pm

One of our 777s a few months ago started having an arcing window in the cruise on the way to manila.

It's amazing that the arcing could be noticeable from inside the cockpit. How common is that? Could that be an overheated window pane? It must be damn scary to see the window melting right in front of you at 900 Km/h  Wow!

-Alfredo


 
chdmcmanus
Posts: 372
Joined: Wed Mar 21, 2001 12:53 am

RE: Window Heat Inoperative?

Wed Jun 02, 2004 12:29 am

The arcing isn't as bad as the shattering. The arcing just looks like St Elmos fire in the corner of the window, but when the window shatters (due to the rapid change in temperature when the sys is turned off) it sounds like a shotgun blast. We (DC-10) have no structural or speed limitations with a shattered windshield, but everyone tightens their seatbelts anyway!

ChD
"Never trust a clean Crew Chief"
 
shark
Posts: 52
Joined: Thu Jun 23, 2005 10:24 pm

RE: Window Heat Inoperative?

Wed Jun 02, 2004 7:16 am

"The rain repellant systems on all Boeing AC were deactivated years ago by Boeing. I'm not sure of the reason. Anyone out there care to enlighten?"

I think it has to due with enviromental issues. That RainBoe is some pretty nasty stuff. I work for AS and we still have rain repellant on our 737-200/400 and MD80's.

 
MD11Engineer
Posts: 13916
Joined: Sun Oct 26, 2003 5:25 am

RE: Window Heat Inoperative?

Wed Jun 02, 2004 12:24 pm

For those who don´t work on planes, if they speak of a window shattering or cracking, it usualy meansc that one of the mineral glass layers cracks. A typical airliner windshield is about 2 inches thick and resembles armoured glass (it is also VERY heavy). It usualy consists of layers of mineral glass alternated with layers of clear plastic. Inbetween the two most outward layers is another invisible, very thin conductive layer (a metal film evaporated on) carrying the current for heating the window.
Each layer is strong enough to carry the whole cabin pressure.

Jan
Je Suis Charlie et je suis Ahmet aussi
 
dab920
Posts: 86
Joined: Wed Jul 11, 2001 5:00 am

RE: Window Heat Inoperative?

Wed Jun 02, 2004 7:07 pm

We are in the process of testing out a new permanent rain-repellant coating on our flightdeck windows. The repellant spray was removed from our fleet a few years ago.

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