Hawker 900XP on departure from Grand Junction, CO

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Initially leveled at FL200 and 285kt. Then airspeed began to drop while maintaining FL200, all the way down to 180kt or so, seemingly followed by possible stall/spin, 15,000 ft/min descent to the smoking hole.

Was AP engaged and nobody did anything in response to an engine failure? Would failure of a single engine cause that? Was it intentional? Were they at FL200 w/o pressurization long enough to lose consciousness?

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Accident Hawker 900XP N900VA,

A Hawker 900XP, N900VA, was destroyed when it impacted terrain near Loma, Colorado. Both pilots were killed. ADS-B data suggests that the aircraft took off from Grand Junction Airport, C...
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Sounds like it was a post-maintenance flight, and depending upon what they did in maintenance with the leading edges, a stall test may be required. This looks like a stall test gone bad.
 
MauleSkinner said:
Sounds like it was a post-maintenance flight, and depending upon what they did in maintenance with the leading edges, a stall test may be required. This looks like a stall test gone bad.
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That is the word on the street, that this was a repositioning flight after maintenance but work had been done on the TKS system that required a stall test. They had planned to do the test enroute.
 
RIP. That seems wild that the airplane went into such an aggravated spin that they could not recover from 20k feet? I have no experience with Biz jets, I look forward to hearing from those that do.
 
TipTanks said:
RIP. That seems wild that the airplane went into such an aggravated spin that they could not recover from 20k feet? I have no experience with Biz jets, I look forward to hearing from those that do.
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The manufacturer says that the stall test should be conducted now less than 10,000 feet above ground or clouds, if that gives you any indication.
 
TipTanks said:
RIP. That seems wild that the airplane went into such an aggravated spin that they could not recover from 20k feet? I have no experience with Biz jets, I look forward to hearing from those that do.
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Jets, especially swept wing jets, can take thousands, even tens of thousands, of altitude to recover from a stall, with or without a spin. It can be especially aggravated if the recovery is attempted to soon.

Rarely does jet training involve doing actual stalls in the aircraft, usually only in the sim, for this very reason. It wasn't until this accident that I have heard of a post maintenance test flight requiring stalls to be performed. That sounds like a very unusual procedure to me, but is apparently known for this type.

Apparently this type uses TKS for an anti-icing system. If the TKS panels are removed for maintenance, then a test flight including stalls is to be performed looking for unusual stall characteristics if a panel is not installed just right. I haven't heard what you are supposed to do it you find these unusual stall characteristics.
 
midwestpa24 said:
Jets, especially swept wing jets, can take thousands, even tens of thousands, of altitude to recover from a stall, with or without a spin. It can be especially aggravated if the recovery is attempted to soon.

Rarely does jet training involve doing actual stalls in the aircraft, usually only in the sim, for this very reason. It wasn't until this accident that I have heard of a post maintenance test flight requiring stalls to be performed. That sounds like a very unusual procedure to me, but is apparently known for this type.

Apparently this type uses TKS for an anti-icing system. If the TKS panels are removed for maintenance, then a test flight including stalls is to be performed looking for unusual stall characteristics if a panel is not installed just right. I haven't heard what you are supposed to do it you find these unusual stall characteristics.
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That was going to be my next question... why a stall test after TKS maintenance... and what happens if the stall test goes wrong.. interesting.
 
TipTanks said:
That was going to be my next question... why a stall test after TKS maintenance... and what happens if the stall test goes wrong.. interesting.
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If they dismantle the leading edges, they have to make sure they’re aligned correctly when they’re reassembled.

If the stall test doesn’t pass, you take it back to get things realigned and try again.
 
MauleSkinner said:
If they dismantle the leading edges, they have to make sure they’re aligned correctly when they’re reassembled.

If the stall test doesn’t pass, you take it back to get things realigned and try again.
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Or if they’re really misaligned you crash and die?
 
If some combination of tks panels are removed or the entire leading edge on either side is removed a stall test flight needs to be performed.
Stall test flight is to detect the activation point of the stick shaker and then the stick pusher. You dont have to stall the plane. Just get close to check those two items.
 
A bit of a long shot, but could it be a case of "forgot to pressurize the aircraft"?

20 thousand feet won't make you go to sleep (at least not immediately) but you will be goofy enough to botch a stall recovery. People will answer "four" to the "how many three cent stamp are in a dozen?" question after spending 3-4 minutes at at 22-25k.
 
If one pulls back the power and holds altitude using the AP, will the AP allow a true stall? Or would a stall before the AoA indicated it to the system be a real problem on AP?
 
I can confirm the Hawkers are over built. This one had it's right engine shot off by a missile over Africa some years ago, it landed safely.
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Hybridss said:
If some combination of tks panels are removed or the entire leading edge on either side is removed a stall test flight needs to be performed.
Stall test flight is to detect the activation point of the stick shaker and then the stick pusher. You dont have to stall the plane. Just get close to check those two items.
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Not trying to be argumentative, but what happens when the shaker and pusher don't activate during this test?
 
midwestpa24 said:
Not trying to be argumentative, but what happens when the shaker and pusher don't activate during this test?
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Go back and have it adjusted. They know at what speed the shaker will activate. Reach that speed and no shaker? Test over, recover and go back to maintenance.

Or just continue the stall, keep slowing hoping something will happen. Of course at that point, they become test pilots.
 
Doc Holliday said:
Go back and have it adjusted. They know at what speed the shaker will activate. Reach that speed and no shaker? Test over, recover and go back to maintenance.

Or just continue the stall, keep slowing hoping something will happen. Of course at that point, they become test pilots.
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I think that was the part I was getting at since I don't know the test procedure. Do you test until the shaker or the stall, whichever comes first? From your first comments, I know see the testing picture a little better, slow to the speed that the shaker should activate, and if it doesn't abort the test and return. Not fly until the stall, at least in theory.
 
midwestpa24 said:
I think that was the part I was getting at since I don't know the test procedure. Do you test until the shaker or the stall, whichever comes first? From your first comments, I know see the testing picture a little better, slow to the speed that the shaker should activate, and if it doesn't abort the test and return. Not fly until the stall, at least in theory.
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The stall warning will activate at a predetermined speed. The shaker will also activate at a predetermined speed. Once the aircraft slows to the first speed, you either have it or don't. If you don't, test over and go back.

There is no reason to take the aircraft into a actual stall.
 
On the 800 series Hawkers all have a stick shaker and a stick pusher. The shaker is electric and the pusher is hydraulic actuated.
The shaker is the stall warning and the pusher is the stall identification. There are no other horns or lights. The AP will disconnect on stick shaker activiation.
All this is from my Hawker 800XP manual.
 
Doc Holliday said:
The stall warning will activate at a predetermined speed. The shaker will also activate at a predetermined speed. Once the aircraft slows to the first speed, you either have it or don't. If you don't, test over and go back.

There is no reason to take the aircraft into a actual stall.
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Speed, or AoA, using the AoA fin on the plane?
 
Been over a decade now since I've flown a Hawker, but I've flown all of the HS-125 models, from the 1A to the 900XP.

I've done a few of these stall tests. They're usually done when the leading edge TKS panels require adjustment, repair or replacement. The manufacturer specifies specific conditions and procedures (attached). They have the potential to be rather unpleasant and I did not go out of my way to pursue opportunities to perform them. A background in aerobatics (particularly spin training) is helpful in performing these tests; note the bold "CAUTION" note under "Stall Characteristics." There is a non-zero chance the crew performing the test will be required to recover from an unusual attitude using non-standard - for business jets, anyway - recovery techniques. It is definitely a procedure best flown by pilots in which at least one flight crew member has experience with them. This is way off the reservation of normal ops.

Most of my stall tests were benign, but I did encounter a very sudden roll rate during one of the procedures, in a Hawker 400A. Recovery from a stall in a swept-wing jet is a very different animal... I would view 15,000 feet AGL as the bare minimum altitude at which to conduct the procedure.
 

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This is a tremendous loss. The pilot was highly-skilled and a wonderful human being. This is painful.
 
Couple of interesting points raised. I agree, this is a horrible accident ...

 
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