Author Topic: King Air Survives Structural Damage  (Read 10361 times)

Offline TheSoccerMom

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King Air Survives Structural Damage
« on: February 09, 2007, 07:33:31 AM »


Just saw this and thought it was quite the story!

"On Feb. 2, Super King Air B200 N77AJ survived an uncontrolled descent and structural damage after the inner ply of the windshield cracked at 27,000 feet and the pilots depressurized the airplane and disconnected the autopilot.  According to the NTSB, the crew was unable to use the oxygen system and evidently lost consciousness.  They revived below 10,000 feet, managed to recover control of the aircraft and made an emergency landing at Cape Girardeau, Mo.  The horizontal stabilizer, elevators and wings were severely damaged."

The article continues to mention the windshield construction, two parts with a Mylar layer in between, and they said the crack first appeared in the lower left-hand corner.  The NTSB stated that the O2 system functioned normally when tested.  [from Aviation International News].

We had a windshield shatter but remain in place after we hit a duck (we think -- apologies to Turbomallard!!!) at 17,500 feet one night, also in a King Air B200.  The Mylar held the saggy mess in place, and we landed without further excitement, but it was hard to see and since it was at night, the shattered pieces turned the airport lighting into millions of pretty starbursts.  Though, we didn't really think they were too pretty THAT night!    ::sweat::

It's great these pilots got down safely!!!!!!   |:)\ 
Don't make me come back there!!!!

Offline Baradium

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Re: King Air Survives Structural Damage
« Reply #1 on: February 09, 2007, 10:10:24 AM »
Pictures of the aircraft are posted on our bulletin board at work.   The story does not do it ANY justice without them.

The wings have creases in them and most of the horizontal stab is *gone*.   The first half of it seems to be peeled off and back over the top and half of the elevator is gone.


For those not familiar with King Air systems  (they are the same as on the Beech 1900 I fly), the oxygen system has a pull knob on the captain's side on the far left side of the panel for oxygen.   Most of the captains I fly with leave it pulled out in flight as there is a risk of the valve being frozen at altitude (however slight).  It also means you have to use precious seconds to pull the valve in an emergency.    This means that if you just don the oxygen mask, there is no O2 until the knob is pulled.   Sounds like either they forgot to pull the knob or the valve was frozen when they tried to.   I do fly with an occasional captain who doesn't pull the knob.   I imagine all the regular king airs are the same...

The passenger oxygen system for us is deployed by a second knob under the first one.


The article that accompanied the pictures I saw at work stated that the aircraft was extremely difficult to recover and once recovered they could *only* maintain IIRC 160 kts in level flight.   Attempts to increase airspeed let to a climb, attempts to reduce it led to a descent.       

I'll see if I can post pictures





http://www.aero-news.net/news/commbus.cfm?ContentBlockID=9e31e19e-6834-497b-96bd-3e8848d38561&Dynamic=1   
This article has pictures, although it's not the article I read from work.
"Well I know what's right, I got just one life
In a world that keeps on pushin' me around
But I stand my ground, and I won't back down"
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Offline Gulfstream Driver

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Re: King Air Survives Structural Damage
« Reply #2 on: February 09, 2007, 03:46:05 PM »
Whew! :o
Behind every great man, there is a woman rolling her eyes.  --Bruce Almighty

Offline Baradium

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Re: King Air Survives Structural Damage
« Reply #3 on: February 10, 2007, 08:40:51 AM »
We dug out our checklists today out of curiousity...  at least in the 1900 the checklist specifically tells you not to dump cabin pressure for a windshield cracking situation... 

However, the one for side windows *does,* maybe they looked at the wrong one?
"Well I know what's right, I got just one life
In a world that keeps on pushin' me around
But I stand my ground, and I won't back down"
  -Johnny Cash "I won't back Down"

Offline BrianGMFS

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Re: King Air Survives Structural Damage
« Reply #4 on: February 10, 2007, 10:20:05 PM »
We had one of our King Air C-90's windshields cut loose last winter on a flight (the inner glass was totally shattered on the FO's side). the crew declared an emergency, descended to below 10,000 then depressurized...landed without incident and later in the day flew the plane back home on a ferry permit. Last week we also replaced a windshield in on of the King Air's due to a a spot that looked like it was delaminating....


Brian

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Offline FlyboyGil

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Re: King Air Survives Structural Damage
« Reply #5 on: February 10, 2007, 10:52:08 PM »
We had one of our King Air C-90's windshields cut loose last winter on a flight (the inner glass was totally shattered on the FO's side). the crew declared an emergency, descended to below 10,000 then depressurized...landed without incident and later in the day flew the plane back home on a ferry permit. Last week we also replaced a windshield in on of the King Air's due to a a spot that looked like it was delaminating....


Brian

What airline is that? So not to fly? :D :D
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Re: King Air Survives Structural Damage
« Reply #6 on: February 10, 2007, 10:55:30 PM »
Just reading the article, it looks as if the windshield failure somehow caused the rest of the airplane to get all bendy and break.
Is there more to the story? Most folks get 'all' their 'knowledge' from the mainstream news sources and may get the idea that
these airplanes are unusually fragile.

Offline Baradium

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Re: King Air Survives Structural Damage
« Reply #7 on: February 11, 2007, 12:18:28 AM »
Just reading the article, it looks as if the windshield failure somehow caused the rest of the airplane to get all bendy and break.
Is there more to the story? Most folks get 'all' their 'knowledge' from the mainstream news sources and may get the idea that
these airplanes are unusually fragile.



The windshield failure and the airplane getting "bendy" aren't really related except by the windshield causing the crew's actions.

What happened is the crew dumped the cabin pressure (normally it's pressurized so it's like you're at a lower altitude).   They failed to get oxygen (reasons unknown at this time) and passed out.   When they came to they were in the descent.

Now, the aircraft isn't going to react very much from just losing cabin pressure and the windshield won't really cause a problem with the flight characteristics since it didn't actually break.

It's unclear to me whether they tried to initiate an emergency descent or not after they disconnected the autopilot.

Emergency descent for a B1900 (should be very similiar or the same to this kingair):

Props forward
Power Idle   (the two combined is a LOT of drag to slow you down).
Flaps takeoff (once below speed)
Gear Down  (once below speed, 180 kts).
Maintian 180 kts and 30 degrees of bank.

This keeps you below any limitations on the airframe while keeping you in a very fast descent.


Obvious from the start is that they easily exceeded 180 kts.   They also would have exceeded barber pole (mach related limitation that changes with altitude) and I'd bet Vne.   How fast they tried to initiate a recovery at high speeds may have also affected the airframe (the last thing you want to do is just yank back on the yoke trying to level off as that can cause damage like you see).   Above manuevering speed (188 kts in a 1900) full control deflection can cause aircraft damage and the aircraft will not stall before exceeding limitations.


My guess is they never got to the point of starting the emergency descent checklist, but I'm not sure.  Pictures of the flaps would help indicate whether they were deployed as well as the gear doors.     My theory is they somehow had a pull to the left or the right and the aircraft rolled over on its back, starting the descent as it rolled.  This could be either trim related or one of the pilots giving input as he started to pass out and holding the force in as he was passing out.  That's the only way that the aircraft would vary that much from its trimmed airspeed that I can think of.   Once you start getting to the 90 degree point (in bank) the airspeed will be climbing dramatically and once the aircraft is on it's back the trim forces pitch it down as they attempt to decrease airspeed, increasing pitch with the increase in airspeed resulting in a very rapid airspeed gain.   This is essentially a Split S manuever   (think, roll inverted and do a half loop to come out on the bottom in level flight).   Without props up and idle power, the amount of drag is significantly reduced.  Even if the manuever is possible given an appropriate aircraft configuration,  I doubt it is with cruise power set on the aircraft.

"Well I know what's right, I got just one life
In a world that keeps on pushin' me around
But I stand my ground, and I won't back down"
  -Johnny Cash "I won't back Down"

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Re: King Air Survives Structural Damage
« Reply #8 on: February 11, 2007, 04:08:14 PM »
...which illustrates my point nicely. Thanks.
 |:)\

Offline TheSoccerMom

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Re: King Air Survives Structural Damage
« Reply #9 on: February 16, 2007, 11:18:34 PM »
Here is a link to a local TV station where the King Air finally got back on the ground.  Some of the comments don't match what I have read so far, e.g., that the pilots depressurized the a/c (TV says the windshield blew out - it didn't), and that the pilots "came to" around 10,000 feet (TV says around 7,000 feet). 

Hope this works, it's worth it to see the damage:

http://www.kfvs12.com/global/video/popup/pop_player.asp?ClipID1=1213165&h1=Emergency%20Landing&vt1=v&at1=News&d1=223734&LaunchPageAdTag=Homepage&activePane=info&playerVersion=1&hostPageUrl=http%3A//www.kfvs12.com/&rnd=66579360

 
Don't make me come back there!!!!

Offline TheSoccerMom

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Re: King Air Survives Structural Damage
« Reply #10 on: February 16, 2007, 11:20:15 PM »
Sorry gang, I am doing something wrong here with the link but have been trying for some time to figure out WHAT.   ::banghead::

I'll keep trying!!!!     ::loony::
Don't make me come back there!!!!

Offline TheSoccerMom

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Re: King Air Survives Structural Damage
« Reply #11 on: February 16, 2007, 11:24:33 PM »
Well, it does work if you copy it into your address line...  sorry I am so technologically challenged!!  Now you really know why I love OLD airplanes...  just my SPEED....  ahem.....

 8)     8)      8)
Don't make me come back there!!!!

Offline switchtech

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Re: King Air Survives Structural Damage
« Reply #12 on: February 17, 2007, 03:37:48 PM »
Well, it does work if you copy it into your address line...  sorry I am so technologically challenged!!  Now you really know why I love OLD airplanes...  just my SPEED....  ahem.....

 8)     8)      8)

We're those photo's posted of you in another thread recent?  'cause you don't look old in them.  ::wave::   Now me on the other hand (the one picture I posted of getting my Solo certificate is a long time ago - when I still had color in my hair that wasn't added in...  :o
The sky and land joined for one brief moment, then we flew - the ground a receding memory for just a little while.

Offline TheSoccerMom

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Re: King Air Survives Structural Damage
« Reply #13 on: February 17, 2007, 08:56:18 PM »
Oh dear, now I will have to wonder if my disguises are up to date...  Hmmm...  I am not sure which photos those would be?   :P

But, I feel I could probably beat most folks around here in an Old Age contest...  Hmmmm...   "Gentlemen!  Start your walkers!!"    (Well, maybe I am not quite to that stage YET...)  Though I do see myself still hobbling out to the airplane decades from now.....   :D    :D    :D
Don't make me come back there!!!!

Offline Gulfstream Driver

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Re: King Air Survives Structural Damage
« Reply #14 on: February 26, 2007, 05:19:42 PM »
Back to the video, I'm surprised they allowed that guy to film the plane after they landed.  Wouldn't the company want to keep a lid on that until after the investigation?
Behind every great man, there is a woman rolling her eyes.  --Bruce Almighty