King Air crashed into FSI Witchita

[Autothrust Blue]

So you need oil pressure of some kind then, right? No oil pressure, aux pump fails, and/or linkage failure, the prop is stuck in whatever position this happens in, correct?

I have a feeling the props systems are identical or similar, with different names for the components. Short of a linkage failure, the 120 has the pitch stop gap that would turn it into a fixed pitch propeller basically. With complete loss of oil pressure to the propeller system and an otherwise functioning engine. The aux feather can over-ride this.

You are referring to the pitch-lock gap, the actuation of which results in about a 1.5% increase in Np following a loss of oil pressure if memory serves. If any oil is left at all, then yes- the aux pump can be used to fx the prop.

If not...do not reduce speed below 115 KIAS.

 

[Tommay85]

You are referring to the pitch-lock gap, the actuation of which results in about a 1.5% increase in Np following a loss of oil pressure if memory serves. If any oil is left at all, then yes- the aux pump can be used to fx the prop.

If not...do not reduce speed below 115 KIAS.

You know what I mean!

Dry motoring, 20 seconds after feathering for shutdown, ect... To refill the auxiliary oil-tank, whatever it's called. Like I said earlier, focused on another plane right now...

 

[milleR]

So you need oil pressure of some kind then, right? No oil pressure, aux pump fails, and/or linkage failure, the prop is stuck in whatever position this happens in, correct?

I have a feeling the props systems are identical or similar, with different names for the components. Short of a linkage failure, the 120 has the pitch stop gap that would turn it into a fixed pitch propeller basically. With complete loss of oil pressure to the propeller system and an otherwise functioning engine. The aux feather can over-ride this.

The oil for alternate feather is drawn from a separate reservoir specifically for that purpose.

 

[etflies]

Oh no, I wasn't commenting on the crash at all, just the reason the 120 prop is the way it is. The reason the book gave at least.

I know there's guys with Dash 8 and Saab time on here. Curious if their prop control systems were the same (requiring oil pressure to move the prop). Or even VERY big props like a C130 or P3. Or even old VERY big props found on the front of radials back in the day.

That prop control schematic for the Bro makes me go fetal and whimper a little bit. It's been a spell since I was on the Saab but the props were not fail deadly like the Brophus. If you had a failure and/or lost oil pressure they were driven toward feather (called auto-coarsen on the Dowty props because they couldn't be guaranteed to actually feather every time) but I don't recall the exact mechanics of how it all happened. I believe they required oil pressure to be driven away/out of feather but I'm sure someone with better knowledge/more recent experience can correct any mistakes I might've made here. I un-learned an awful lot on that airplane in order to cram Brasilia knowledge in.


Incidentally I suddenly have a whole new appreciation for the Airbus and it's training program.

"What's this fault light mean?"

"There is a fault in that system."

"Good job, let's go get a beer."

 

[Autothrust Blue]

The oil for alternate feather is drawn from a separate reservoir specifically for that purpose.

Which, once you've shot the electric-FX once, takes 20 seconds to refill, assuming any oil pressure is available from the engine system.

My point is, it's entirely possible to wind up with that prop out of your control and failed-fixed against the pitchlock without oil. At least I think that was my point. Fail-deadly.

 

[Autothrust Blue]

Incidentally I suddenly have a whole new appreciation for the Airbus and it's training program.

"What's this fault light mean?"

"There is a fault in that system."

"Good job, let's go get a beer."

PREFLIGHT CHECKLIST
Power button - PUSH ON
--- END OF PROCEDURE ---

 

[kiloalpha]

Ugh... this thread gave me cancer.

NTSB Probable Cause: http://www.ntsb.gov/_layouts/ntsb.a...187-4e6f-a778-ad3b6a8640ec&pgno=19&pgsize=200
NTSB Docket Report: http://dms.ntsb.gov/pubdms/search/h...2249f2b3a-92B5743E-F390-93E2-263F2FF76D61E083

TL;DR: Pilot failed to maintain lateral directional control after a power reduction in the left engine which resulted in a crash.

Pretty sure everyone comparing the King Air 200 to PC12/C208/EMB-120/Metro/Speedster2000 is adding just speculative mumbojumbo to the discussion. This particular King Air that crashed had PT6A-52 engines with 4 blade Hartzell propellers. Both engines were turning at impact. Neither propeller was feathered. It is solely on pilot error.

 

[AAPalmTree]

Ugh... this thread gave me cancer.

NTSB Probable Cause: http://www.ntsb.gov/_layouts/ntsb.a...187-4e6f-a778-ad3b6a8640ec&pgno=19&pgsize=200
NTSB Docket Report: http://dms.ntsb.gov/pubdms/search/h...2249f2b3a-92B5743E-F390-93E2-263F2FF76D61E083

TL;DR: Pilot failed to maintain lateral directional control after a power reduction in the left engine which resulted in a crash.

Pretty sure everyone comparing the King Air 200 to PC12/C208/EMB-120/Metro/Speedster2000 is adding just speculative mumbojumbo to the discussion. This particular King Air that crashed had PT6A-52 engines with 4 blade Hartzell propellers. Both engines were turning at impact. Neither propeller was feathered. It is solely on pilot error.

I've got some time in the speedster 2000.

 

[dustoff17]

I've got some time in the speedster 2000.View attachment 34528

That's one hell of a set of winglets!!

 

[ppragman]

Ugh... this thread gave me cancer.

NTSB Probable Cause: http://www.ntsb.gov/_layouts/ntsb.a...187-4e6f-a778-ad3b6a8640ec&pgno=19&pgsize=200
NTSB Docket Report: http://dms.ntsb.gov/pubdms/search/h...2249f2b3a-92B5743E-F390-93E2-263F2FF76D61E083

TL;DR: Pilot failed to maintain lateral directional control after a power reduction in the left engine which resulted in a crash.

Pretty sure everyone comparing the King Air 200 to PC12/C208/EMB-120/Metro/Speedster2000 is adding just speculative mumbojumbo to the discussion. This particular King Air that crashed had PT6A-52 engines with 4 blade Hartzell propellers. Both engines were turning at impact. Neither propeller was feathered. It is solely on pilot error.

My biggest bet is that the throttle friction lock slid back and he just screwed the pooch. In the C90, there are a couple airplanes we have that require a lot of twist on the friction lock to prevent any slippage, and it's not uncommon to see it happen, especially if you jump into one you're not familiar with. I seem to recall this same thing happening in the 1900 and the 99 occasionally. I'd bet that as he takes his hand off the power levers, the left one slides back and it's off to the races - (or at least off to killing my old instructor and the Russian translator I BS'd with when I'd been in that simulator a year or so prior...).

In my mind, this is one of those things that can happen in the airplane that doesn't really happen in the sim. There's not as many vibrations, the sim's friction locks are well maintained and lightly used, etc. Not FSI's fault in the least, if anything, the training I always got there was amazing (and I'm bummed that we're doing our training in house now), but something that should probably be mentioned, I've certainly seen it in the airplane and if you panicked and froze it could kill you. Someone one here - I forget who it was, was talking about the 99 in years past and mentioned that with the autofeather inoperative, VMC on the 99 went up by something like 30kts or something ridiculous? It can't be that much better in a King Air...

Edit to add:

If it was an actual P3 "roll back" as the NTSB report suggests it could have been, autofeather should have deployed and the prop should have been headed to feather. So, either, it was a friction lock letting the power lever slide back (which would make sense from the maintenance that had been done earlier to match up the power levers), or there was a P3 failure and an autofeather failure, which seems exceedingly rare.

 

[deadstick]

@ppragman we were discussing these possibilities at work. Snap-backs on takeoff occur when the pilot moves the right hand from the power levers to the gear handle, but applying max power fixes it. I cannot imagine somebody right out of a type ride in the 350 screwing that up (or for that matter the rudder application or forgetting to arm the AFX). With the loss of Py or P3 air, I wonder if the engine could still make over 260 lbs of torque. If so, the autofeather system would not dump the oil.

As for your question about Vmca, this is from the Raisbeck -52/Quiet Fan supplement:


CAUTION
Using throttle cuts to simulate failures will result in the autofeather system being disarmed. In this configuration the VMCA may be as high as 115 knots. Dynamic cuts should only be attempted at airspeeds above 117 knots.

 

[gotWXdagain]

"Although the pilot had a history of anxiety and depression, which he was treating with medication that he had not reported to the Federal Aviation Administration, analysis of the pilot's autopsy and medical records found no evidence suggesting that either his medical conditions or the drugs he was taking to treat them contributed to his inability to safely control the airplane in an emergency situation."

I wonder if that's a not-so-subtle jab at the FAA to get with the times?

 

[kiloalpha]

With the loss of Py or P3 air, I wonder if the engine could still make over 260 lbs of torque. If so, the autofeather system would not dump the oil.

To answer your question. A failure of Py would result in "min flow" or about 90-100 lbs/hr. The resulting fuel flow would create sub idle N1 speeds probably around 56-58%. There's no way a PT6 can create TQ at these N1 speeds. The autofeather would have kicked in provided the power levers were up and the autofeather switch was in the ARM position (which according to the CVR was.)

Now a loss of N1 input to the FCU would result in an 85-88% N1 "safe mode" for the engine where the engine would still produce some power. More than enough not to trigger an autofeather event but not enough power to make you think it was an engine failure.

 

[ppragman]

@ppragman we were discussing these possibilities at work. Snap-backs on takeoff occur when the pilot moves the right hand from the power levers to the gear handle, but applying max power fixes it. I cannot imagine somebody right out of a type ride in the 350 screwing that up (or for that matter the rudder application or forgetting to arm the AFX). With the loss of Py or P3 air, I wonder if the engine could still make over 260 lbs of torque. If so, the autofeather system would not dump the oil.

As for your question about Vmca, this is from the Raisbeck -52/Quiet Fan supplement:


CAUTION
Using throttle cuts to simulate failures will result in the autofeather system being disarmed. In this configuration the VMCA may be as high as 115 knots. Dynamic cuts should only be attempted at airspeeds above 117 knots.

I really doubt it, to be honest, if you're bored one day and wanted to simulate it in the airplane, you could hold the test switch on the autofeather and bring the power back to idle on one of the engines - it'll feather, just like it's supposed to (at least it will in the 1900 and the system is identical more or less). And that'd be at a higher N1 than with a Py/P3 air failure... That system is highly effective and it dumps oil with the quickness.

 

[T/O w/FSII]

I'm probably the newest 350 guy in this thread. My type is 5 days old.

When we picked up our plane from beech at Witchita, the first take off was a handful. V1, VR, left engine rolled back.

The frictions weren't tight enough. In type school they mentioned nothing about that, but every KA guy I talk to says "oh yea, that'll happen"

 

[deadstick]

What you both said about the P3/Py question fit. I just recalled that min flow is well below idle. We went a few rounds with PWC a few years ago after one of those hot fuel/no acceleration events. I want to say that min flow on our -42s was 40-something % N1.

@kiloalpha As for losing the N1 input, you're talking about the coupling off of the fuel pump? Goes with the "See blue dye, don't fly."

 

[deadstick]

I'm probably the newest 350 guy in this thread. My type is 5 days old.

When we picked up our plane from beech at Witchita, the first take off was a handful. V1, VR, left engine rolled back.

The frictions weren't tight enough. In type school they mentioned nothing about that, but every KA guy I talk to says "oh yea, that'll happen"

Our mechanic told me it's actually an issue with the friction locks not providing uniform resistance throughout the full travel of the levers, specifically. There is more friction at idle so that it's adjusted properly when they're checked. However, at the forward position (takeoff power) the levers have less friction holding them in place.

 

[kiloalpha]

What you both said about the P3/Py question fit. I just recalled that min flow is well below idle. We went a few rounds with PWC a few years ago after one of those hot fuel/no acceleration events. I want to say that min flow on our -42s was 40-something % N1.

@kiloalpha As for losing the N1 input, you're talking about the coupling off of the fuel pump? Goes with the "See blue dye, don't fly."

Yes that old saying is for the -42 engines only with the Bendix FCUs. On the -52, they use Woodward FCU which have a fail safe mode. Also the -42 will have a LOT lower N1% than a -52 during a P3 leak/fail. About 10-15% lower.

 

[deadstick]

Yes that old saying is for the -42 engines only with the Bendix FCUs. On the -52, they use Woodward FCU which have a fail safe mode. Also the -42 will have a LOT lower N1% than a -52 during a P3 leak/fail. About 10-15% lower.

Accoding to the reports, this had -42s.

 

[Inverted]

Props are for boats :stir: