Epidemic of cracked windshields in KDEN, explanation unknown

See

http://us.cnn.com/2007/WEATHER/02/17....ap/index.html

So what would cause windshields to crack on many different types of aircraft
at the same time? It wasn't impact or anything like that. The weather was
not exceptional for a Denver winter. Multiple aircraft models from multiple
manufacturers were affected.

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Feb 17, 11:15 am, Mxsmanic wrote:
See

http://us.cnn.com/2007/WEATHER/02/17....ap/index.html

So what would cause windshields to crack on many different types of aircraft
at the same time? It wasn't impact or anything like that. [..]

I don't believe the "wasn't impact" part. I lived in Denver for a
while, and when the winds whip up, stones fly around. Cracked
windshields and dust-storm-scarred paint can be quite common out
there.

Kev

"Kev" wrote in message
ups.com...
On Feb 17, 11:15 am, Mxsmanic wrote:
See

http://us.cnn.com/2007/WEATHER/02/17....ap/index.html

So what would cause windshields to crack on many different types of
aircraft
at the same time? It wasn't impact or anything like that. [..]

I don't believe the "wasn't impact" part. I lived in Denver for a
while, and when the winds whip up, stones fly around.

That brought to mind the skit in "Monty Python and the Holy Grail" about
things that will float in water, one of them being small rocks.

How cold did it get in Denver? Aluminum and plastic have
different contraction rates with cold. Plastic also gets
brittle with cold. Wind flexes wing, which also flexes
fuselages, erg---cracks.



"Matt Barrow" wrote in message
...
| "Kev" wrote in message
|
ups.com...
| On Feb 17, 11:15 am, Mxsmanic
wrote:
| See
|
|
http://us.cnn.com/2007/WEATHER/02/17....ap/index.html
|
| So what would cause windshields to crack on many
different types of
| aircraft
| at the same time? It wasn't impact or anything like
that. [..]
|
| I don't believe the "wasn't impact" part. I lived in
Denver for a
| while, and when the winds whip up, stones fly around.
|
| That brought to mind the skit in "Monty Python and the
Holy Grail" about
| things that will float in water, one of them being small
rocks.
|

On Feb 17, 5:14 pm, "Jim Macklin"
wrote:
How cold did it get in Denver? Aluminum and plastic have
different contraction rates with cold. Plastic also gets
brittle with cold. Wind flexes wing, which also flexes
fuselages, erg---cracks.

Denver is considered "high plains desert", and is actually quite
moderate. Average temperature in February is around 33 degrees. It's
not unusual to get a blizzard, and then be out in short sleeves the
next day. (It'll be around 50 F tomorrow! )

It'd be a heckuva lot colder in many other places, so cold windshield
cracks make no sense, unless they used the wrong heating process as
Bob Moore suggests.

On the other hand, they mentioned 100 mph ground winds, and that means
flying rocks to me. Windshield replacement is a big business out
there due to so much gravel on the roads

Kev

Kev wrote:

On the other hand, they mentioned 100 mph ground winds, and that means
flying rocks to me. Windshield replacement is a big business out
there due to so much gravel on the roads



A few decades back we toured the s/e part of Australia by car. At the more
rural towns, the first signs you saw were advertisements for windscreen
replacement. Metal screens in front of your windshield (windscreen) and
headlights were a common sight............

"Kev" wrote in message
ups.com...
On Feb 17, 5:14 pm, "Jim Macklin"


On the other hand, they mentioned 100 mph ground winds,

Who is "they"?

and that means
flying rocks to me.

As those are borderline tornado winds, it's more like regular debris.

--
Matt Barrow
Performance Homes, LLC

Jim Macklin wrote:
How cold did it get in Denver? Aluminum and plastic have
different contraction rates with cold. Plastic also gets
brittle with cold. Wind flexes wing, which also flexes
fuselages, erg---cracks.

It can't be as cold as the jets routinely see above 30,000 feet. I
suspect the wind was carrying stones or ice chunks or something like
that which cracked the windshields.


Matt

Matt Whiting wrote:

Jim Macklin wrote:

How cold did it get in Denver? Aluminum and plastic have
different contraction rates with cold. Plastic also gets
brittle with cold. Wind flexes wing, which also flexes
fuselages, erg---cracks.

It can't be as cold as the jets routinely see above 30,000 feet. I
suspect the wind was carrying stones or ice chunks or something like
that which cracked the windshields.

I suspect the the crews turned on the electric windshield heating without
proper warmup when it was very cold, and the cracks resulted from thermal
stresses in the windows. The cracks were reported to have happened in the
air, where flying rocks would be rare, and not on the ground.

"Jim Macklin" wrote in message
news
How cold did it get in Denver? Aluminum and plastic have
different contraction rates with cold. Plastic also gets
brittle with cold. Wind flexes wing, which also flexes
fuselages, erg---cracks.


Single digits below zero. Nothing.

Certainly not "rocks blowing around".


| I don't believe the "wasn't impact" part. I lived in
Denver for a
| while, and when the winds whip up, stones fly around.
|