View Full Version : Loud popping from windows C550

28th Feb 2008, 15:55

It happens on just about every other flight on more than one aircraft. The cockpit side windows will make an almighty popping sound once at TOC or early cruise. It will only happen once. Engineers say that it's just the windows seating themselves.

Do other types suffer from this terrifying characteristic? What about the newer CJ series? :} My nerves are just about as shot as the old aeroplane.

G-SPOTs Lost
28th Feb 2008, 16:39
Had it happen a few times on a Citation II but never on the Bravo, also without teaching you how to suck eggs - suggest you check under the seat for a screw top plastic bottle, I know it sounds silly but the noise they make can be very disconcerting as they inflate and deflate.......

Had to buy the engineers a few cold ones over that particular entry.......:{

28th Feb 2008, 19:48
On the CRJ200 it was very usual. Engineers told me it was due the crystal was not totally fixed to the frame. It was that way to permit different expansion of the cell and the crystal due to presurization. All that noises are frightening, but it doesnít mean something bad must happen.:}
The fact is I flew Crj more than 4 years and during that time I suffered 2 windows crashed in flight. Cockpit windows are made of several layers. The CRJ200 windshields are 3. I donít remember if side windows were 2 layers. Interior and exterior are crystal. The intermediate it is a kind of polycarbonate.
First crash was the interior layer of the right side window. Flying FL360, right before beginning of the descent for the APP. It sounded like a little explosion, followed by a straight cut from one corner to the opposite. I began to descend and during the descent small cuts were produced at small intervals from the main cut in random directions. In a few minutes little pieces of crystal fell down over the first officer who left his seat for the rest of the app. At the ldg the crystal stopped to crash.
The second was close to Zurich at FL350. The explosion was bigger and the interior layer of the left front window was totally broken in small pieces. It was impossible to see through. I initiated a soft descent while deviating to LYS. At our arrival I took a couple of pictures, sent them to my company and the next day I had a ferry authorization and a brief analysis from Bombardier to fly back to Spain. I made the fly depressurized at 7000ft 180 Knt without incidences.
Since then I am always looking at the different types of window. I have realized that they are usually flat crystal. But there are small airplanes with big windows that follow the curve of the cell. If you look trough that type of windows you will notice that the vision is deformed at some points indicating that this is not it natural shape and they have been forced to it. These are dangerous to my opinion. I believe if windows are flat or almost support better the cell expansion. At least the expansion is more lineal and it doesnít produce that crack sound. The Fokker 50 has a nosy crack perfectly audible all over the airplane, produced by the big pax door when it adjusts to the expanded frame.
Good luck.:rolleyes:

CJ Driver
1st Mar 2008, 13:55
The CJ's make banging noises from around your feet in the cockpit, not from the windows. I believe it is the forward pressure bulkhead "adjusting", but it can definitely make me jump - even when I've heard it a hundred times before. Usually happens passing the mid twenties in the climb, a loud "thunk".

1st Mar 2008, 15:48
Hi, from time to time same strange occurance while flying a c560 ultra..& same conclusion from tech dept.

I try different setting for the cabin climb rate..but no change..in addtion I always select a higher cabin altitude regarding the cruising level in order to avoid a max psid , reducing a little bit the pressure solicitations on the structure..

2nd Mar 2008, 07:42
Ok it sounds like something you just have to get used to. However, PPPPilot, I don't think your run of bad luck is something to get used to! You mention curved windows . . . . . Citation has very large and very curved windows. :uhoh: Thanks for info.

2nd Mar 2008, 08:05
Not Sure about the 550 but the 560 had an SB to fit nylon slip washers/spacers at the glare shield mounting points on the left and right corner next to the side windows. This cured the strange noises we were getting.

2nd Mar 2008, 18:57
Good problem solving guys..

Yeah plastic bottles, pop cans, anything sealed that is changing pressure.
In the older planes, popping was pretty common..if you ever saw a pic of a plane, from the outside at altitude, you could see the skin expansion..

In a Citation...never saw this...if the windows are moving back and forth somehow on the screws, then get those checked, that's creating wear that shouldn't be there... Many times the windows don't make inspections, because they are cracked at the connection points, which made me wonder if the techs tightened them down to too much to begin with....but,...I am starting to wonder now if the pressurization is putting enought stress on those screws to pop this and that.crack those connections...again, never heard noises...

If you can isolate this, that's best....not coming from your storm window?

Another idea is that the skin on your side is 'soda canning', again, expansion of the skin...

2nd Mar 2008, 21:28

I can tell you the captain I fly with almost jumps out of his seat when it happens...his nerve's must almost be shot be now.. :):) It's just as well he's got the seat belts on..:}

3rd Mar 2008, 07:46
C550's do tend to crack a little most of the time, some do, some don't. Again I believe this is the pressure bulkhead adjusting from my experience's.

Occasionally in one of ours it makes an almighty Bang and scares the **** out of me every time ! used to do it all the time but sems better now. Don't ask me why ?! :rolleyes:

Some XL's I've flown tend to crackle on the way up through the mid 20's aswell.

3rd Mar 2008, 16:55
Essex Boy:

I flew the Cessna 550 between 1981 and 1996 and cannot say that I had the
popping sounds as described.

What I can say is that I had three (3) cases of total loss of pressurization all from 41000 ft. It certainly got my attention, the engineers attention and the attention of the Cessna Company. The model had the pressurization system. modified as a result of the investigation.