Blackhawk Down

brien23

brien23

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Brien
Black Hawk helicopter from the Tennessee National Guard crashed Wednesday in Alabama, killing everyone on board. From the video it looked like straight down?
 
My guess it shed a blade for some reason. Impacted the median of a highway.

Edit: possible transmission lockup
 
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Accident site is right on line for the hold on the GPS 17 into Redstone. RIP.
 
Local news here says it impacted Hwy 53 just north of town. Traffic blocked for near term future.

Heartache for families not just tonight but for years to come. Prayers for them all.
 
Rest easy, warriors.

They risk their lives every day. Even the most benign training exercise can turn deadly, and those who serve do so to keep our country safe. My thanks to all that have answered the call.
 
3393RP said:
Rest easy, warriors.

They risk their lives every day. Even the most benign training exercise can turn deadly, and those who serve do so to keep our country safe. My thanks to all that have answered the call.
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Well stated. Agree wholeheartedly.
 
From the video it looks like the helicopter dropped out of the clouds. IFR and helicopters are not a good mix.
 
Piperonca said:
My guess it shed a blade for some reason. Impacted the median of a highway.

Edit: possible transmission lockup
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Nah, those blades were popping (blade slap) loudly on the ring video. Just came out of the clouds out of control. It reminds me out that vid in NYC when that guy went IIMC in the A109. Diving out of the clouds and barely pulls up over the river and then flys back into IMC.
 
Velocity173 said:
Nah, those blades were popping (blade slap) loudly on the ring video. Just came out of the clouds out of control. It reminds me out that vid in NYC when that guy went IIMC in the A109. Diving out of the clouds and barely pulls up over the river and then flys back into IMC.
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You have better ears than me, thanks. After cranking volume up and sticking my head to the phone I hear the thing at what sounds like operating RPM. Still find it hard to fathom that somebody could get a Black Hawk in that attitude, in the clouds or not. Also note no attempt at recovery. Convinced something mechanical had to come loose or stick, one or the other.

Regarding the A109 that was hard to believe also, but it was single pilot IIRC.
 
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Horrible sounds they make. Audio much louder on your clip.
 
I was a Witness to a blade loss (spindle break) in a Blackhawk at FT Rucker flying a UH-1 out of TacX…the aircraft destroyed itself on the way down…clouds of hydraulic fluid enveloping the aircraft… still etched in my mind 35 plus years later…to absent companions. May they Rest In Peace.
 
@Velocity173 and/or @Warlock: What would happen if they had an un-commanded stabilator movement, like it fully programmed down at normal cruise speed?
 
Flymy47 said:
@Velocity173 and/or @Warlock: What would happen if they had an un-commanded stabilator movement, like it fully programmed down at normal cruise speed?
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At cruise? She’ll try to go inverted on ya. Even the book says longitudinal control will be lost. They had a few accidents early in the 80s due to stab failures going full down and pilots not reacting to it properly.

If it has a hardover though you get a caution light and audio and any pilot SHOULD instinctively react with manual slew up on the cyclic. Never had a hard over while in auto mode but had maybe a half dozen stab failures. Really a non event. Reset the computer, if it fails again you’re in manual from there on out. Slew to zero above 40 KIAS and full down below 40 KIAS.

That’s an interesting observation though and something I didn’t think about. I’m still thinking spatial D but there are a number of failures that could have brought them down. At least caused a big enough distraction while IMC to bring them down.
 
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Velocity173 said:
That’s an interesting observation though and something I didn’t think about. I’m still thinking spatial D but there are a number of failures that could have brought them down. At least caused a big enough distraction while IMC to bring them down.
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Do both the Lima and Mike have the ability to couple to the flight director, or some other autopilot type function? Spatial-D never occurred to me because I figured there's so much automation available.
 
Velocity173 said:
At cruise? She’ll try to go inverted on ya. Even the book says longitudinal control will be lost. They had a few accidents early in the 80s due to stab failures going full down and pilots not reacting to it properly.

If it has a hardover though you get a caution light and audio and any pilot SHOULD instinctively react with manual slew up on the cyclic. Never had a hardcover while in auto mode but had maybe a half dozen stab failures. Really a non event. Reset the computer, if it fails again you’re in manual from there on out. Slew to zero above 40 KIAS and full down below 40 KIAS.

That’s an interesting observation though and something I didn’t think about. I’m still thinking spatial D but there are a number of failures that could have brought them down. At least caused a big enough distraction while IMC to bring them down.
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More discussion here:
https://www.pprune.org/rotorheads/651386-blackhawk-crash-alabama.html#post11386716
 
Flymy47 said:
Do both the Lima and Mike have the ability to couple to the flight director, or some other autopilot type function? Spatial-D never occurred to me because I figured there's so much automation available.
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The Mike is fully automated. Everything, collective, cyclic, pedals. It’ll fly it to 10 ft and then the pilot can use a center controller and bump the altitude down in one foot increments and land basically by itself.

The accident aircraft was a Lima. So no autopilot in that, there’s nothing that will take the controls to track a navaid or descend to a certain altitude. Now, it does have a flight director (CIS) pictured below. If you follow those commands, it’s pretty darn accurate.
5B9982BB-C86A-4738-A27F-61CAA7FFF1A1.jpeg


Both types have Stability Augmentation System / Flight Path Stabilization. Some of this stuff I’m sure you’re familiar with because the Chinook uses similar systems. They essentially make the aircraft as stable as your typical fixed wing GA but with no autopilot (Lima). SAS, deals with stability in oscillations or DYNAMIC stability. Push forward on the stick and let go and SAS will minimize the oscillations. FPS deals with STATIC stability or the aircraft returning to its original undisturbed position. FPS is somewhat of a basic AP in that it will provide an attitude hold and heading hold (yaw). Basically let go of the controls and the trim actuators will keep pointing where you left it.

The stab wraps up the whole show (Automatic Flight Control System) and assists with both dynamic and static stability. So, at a hover it’ll go full down (collective position / speed sensor) to align with the wind. Increase speed (above 30 kts) and it’ll to go trailing edge up to even a negative position at higher speeds (130 ish). It’ll move up and down with gusty winds or increase G Force through vertical accelerometer inputs. It’ll move up or down if you kick it out of trim through lateral accelerometers mounted in the ceiling.

The Mechanical Mixing Unit (MMU) and the canted (20 degrees) tail rotor assist with AFCS but that’s way too long to get into.
 
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Piperonca said:
More discussion here:
https://www.pprune.org/rotorheads/651386-blackhawk-crash-alabama.html#post11386716
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Yeah @Bell206 sent me that. Some are talking about an improper reaction but that’s really not a thing anymore. From what the old IPs told me, the early models didn’t have the cyclic mounted stab slew up switch and the center console switch was opposite in direction that they have now. After a few crashes, they changed all that.

I could understand maybe a delayed reaction. Personally I always had my right pinky on the switch in flight so if it failed, I was ready. It doesn’t slew that fast in auto or manual so it’s not like you’ve got to react quickly either. In fact, not that I’ve ever done an RTT,;) but if you do it aggressively enough, the stab can’t keep up with the acceleration of the aircraft and it’ll try and pitch ya forward.

Honestly, panic mode is to get it to zero no matter what speed. It’s a symmetrical airfoil so really it does a good job at keeping it stable even if you leave it at zero. Even if you forget to slew it full down below 40 kts, it’ll only cause a slight nose pitch up around 20 kts (rotor wash hitting it) then the aircraft goes back to mostly a normal nose up attitude at a hover (6 degrees).
 
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Velocity173 said:
Yeah @Bell206 sent me that. Some are talking about an improper reaction but that’s really not a thing anymore. From what the old IPs told me, the early models didn’t have the cyclic mounted stab slew up switch and the center console switch was opposite in direction that they have now. After a few crashes, they changed all that.

I could understand maybe a delayed reaction. Personally I always had my right pinky on the switch in flight so if it failed, I was ready. It doesn’t slew that fast in auto or manual so it’s not like you’ve got to react quickly either. In fact, not that I’ve ever done an RTT,;) but if you do it aggressively enough, the stab can’t keep up with the acceleration of the aircraft and it’ll try and pitch ya forward.

Really panic mode is to get it to zero no matter what speed. It’s a symmetrical airfoil so really it does a good job at keeping it stable even if you leave it at zero. Even if you forget to slew it full down below 40 kts, it’ll only cause a slight nose pitch up between 10-20 kts (rotor wash hitting it) then the aircraft goes back to mostly a normal nose up attitude at a hover (6 degrees).
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My knee jerk guesstimate to all this was blades coming undone, and that seems to have been a feature on some early Hawks. Next up is the always fashionable SD, which can even affect line captains in the 'big iron'. Then comes the stabilator instigated outside loop. And finally, another mechanical/electrical failure. There has to be a reason that aircraft came out of cloud inverted. I wish the investigators luck in finding all the pieces. Don't know if the Hawk has a voice recorder or not, or if some ATC talk was recorded. Step by slow step, they will figure it out.
 
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Piperonca said:
My knee jerk guesstimate to all this was blades coming undone, and that seems to have been a feature on some early Hawks. Next up is the always fashionable SD, which can even affect line captains in the 'big iron'. Then comes the stabilator instigated outside loop. And finally, a mechanical/electrical failure. There has to be a reason that aircraft came out of cloud inverted. I wish the investigators luck in finding all the pieces. Don't know if the Hawk has a voice recorder or not, or if some ATC talk was recorded. Step by slow step, they will figure it out.
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Mike model has a voice recorder but the Lima doesn’t. At least doesn’t come standard with a CVR. There’s IVHUMS but that’s a basic FDR. Not sure it even records stab position.

Spatial D can happen even in an aircraft like a Mike model that essentially flys itself. Years ago a NG Mike crashed in Navarro FL carrying Marine Force Recon. Night, foggy, several up and down oscillations and finally plowed into the water. My last IE checkride I took with a guy at Rucker, he died maybe 3 months later doing an IAP in Germany. There was mention of them picking up icing but it’s suspected the primary cause was spatial D. He was set to be awarded the Silver Star too for something he did in Afghanistan a year earlier. Sad deal.
 
I lost five men out of my platoon in Vietnam from spatial disorientation. They took off at night in the monsoon season. It was a flare ship mission to support a gun team. Eyewitness said that the Huey took off, picked up speed at low level then went abruptly up in the air. Somehow he got a couple hundred meters beyond the wire then pitched over completely end over end. Like all the others, it is a sad story. One of the crewmembers was going to go home the next day. He wanted one more flight before he left.
 
I was never a Blackhawk rated although flew familiarization hours as AVLOC test pilot and spent many an hour in the back with a Command Console…UH-1,OH-58, but Primarily AH-1 and AH-64. The early stab failures were and issue but training as discussed eliminated that and spindle failure was a design issue with the making it stronger in simple terms. I wondered about Stab failure the moment I saw this…and old problem that’s new again.
 
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Speaking of stabilator issues in the 60. Interesting story on how the system operates. I was flying in Kosovo one day with an IP. He had left his pitot cover on the left side. Now, the system uses speed sensors from both pitot tubes to position the stab at the optimum angle, and the stab has two actuators that get their signal from either left or right pitot tubes. #1 actuator left pitot tube, #2 actuator right pilot tube. Now below 80 kts the system automatically choses the higher of the two signals and the actuators move as one. In this case, it sees zero on his side and a valid signal on mine, it choses mine. Once you get above 80 kts, the system uses each independent signal and if there’s an mis compare, and it’ll fail the stab right where it’s at. So anyway, there I was on the controls accelerating through 80 kts and the thing fails. IP goes “****! I got no airspeed…I have the controls!” Not sure why he took the controls since my airspeed was fine but whatever. He landed, opened his door and pulled in his pitot cover and gave me back the controls. Rest of the day I gave him crap about doing a proper preflight.

Another thing I was thinking about last night. In this accident it is possible that one of the pilots put something on the center console and jammed the manual slew switch down. That would be bad in the clouds. You can override with the right cyclic switch but it could get ugly if it’s delayed or could even induce spatial D.
 
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Velocity173 said:
Speaking of stabilator issues in the 60. Interesting story on how the system operates. I was flying in Kosovo one day with an IP. He had left his pitot cover on the left side. Now the system uses speed sensors from both pitot tubes to position the stab at the optimum angle, and the stab has two actuators that get their signal from either left or right pitot tubes. #1 actuator left pitot tube, #2 actuator right pilot tube. Now below 80 kts the system automatically choses the higher of the two signals and the actuators move as one. In this case, it sees zero on his side and a valid signal on mine, it choses mine. Once you get above 80 kts, the system uses each independent signal and if there’s an mis compare, and it’ll fail the stab right where it’s at. So anyway, there I was on the controls accelerating through 80 kts and the thing fails. IP goes “****! I got no airspeed…I have the controls!” Not sure why he took the controls since my airspeed was fine but whatever. He landed, opened his door and pulled in his pitot cover and gave me back the controls. Rest of the day I gave him crap about doing a proper preflight.

Another thing I was thinking about last night. In this accident it is possible that one of the pilots put something on the center console and jammed the manual slew switch down. That would be bad in the clouds. You can override with the right cyclic switch but it could get ugly if it’s delayed or could even induce spatial D.
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I can see that happening. Doesn't take much to start the dominoes falling.
 
Velocity173 said:
Spatial D can happen even in an aircraft like a Mike model that essentially flys itself. Years ago a NG Mike crashed in Navarro FL carrying Marine Force Recon. Night, foggy, several up and down oscillations and finally plowed into the water. My last IE checkride I took with a guy at Rucker, he died maybe 3 months later doing an IAP in Germany. There was mention of them picking up icing but it’s suspected the primary cause was spatial D. He was set to be awarded the Silver Star too for something he did in Afghanistan a year earlier. Sad deal.
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I remember sitting in the outbrief from that accident. It was B-A-D. IIRC they ended up climbing while going backwards at 70 knots as they were fighting to get it under control.
 
Flymy47 said:
I remember sitting in the outbrief from that accident. It was B-A-D. IIRC they ended up climbing while going backwards at 70 knots as they were fighting to get it under control.
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Yep. Made no sense why they took that flight. AWOSs all over the area we’re reporting IFR. Then, with an aircraft with that kind of automation, IIMC should have been a no brainer.
 
Not inbound to Redstone like I thought but Huntsville. Lots of vectors, lots of altitude to lose by FAF and ground speed at one point got to 0 knots.
 
Velocity173 said:
Not inbound to Redstone like I thought but Huntsville. Lots of vectors, lots of altitude to lose by FAF and ground speed at one point got to 0 knots.
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This is very relevant. Source or further details?
 
Velocity173 said:
Friend at work is in the TNNG. He knew both pilots when he flew 60s.
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That makes it personal, then. I was sitting here before you replied wondering if one contributing factor wasn't another case of ATC mismanagement?
 
Piperonca said:
That makes it personal, then. I was sitting here before you replied wondering if one contributing factor wasn't another case of ATC mismanagement?
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Well I guess we’ll see in the coming months. Personally, I’m not one to put blame on ATC for excessive vectors if indeed that’s the case. Like the SR22 accident at HOU years ago, as a PIC we’re expected to have a mastery of our aircraft.
 
One of the accidents I investigated a long time ago at KGRK involved an OH-58A which had gotten trapped in IMC on a dark night. He survived long enough to get out a mayday and request GCA into Gray. That tape was not something pleasant to listen to. One of the thoughts a board member had was in the future, when giving no-gyro GCAs, was not to give descending turns. Because the pilot had the aircraft under reasonable control prior to that. Food for thought, indeed.

Edit: back in the day, the first OH-58A models were not fully equipped for known IFR flight, nor were the pilots qualified for instrument flight in CONUS. And worse, this pilot was solo. Until the early '70s, most Army helo pilots had "tac ticket" only, valid for so-called tactical instrument flight. There's more to be said about that, but space and time do not permit.
 
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Velocity173 said:
Kinda odd no cause was given but that's the Army for ya.

www.al.com

Army releases military helicopter crash report, won’t say cause

An Army safety investigation report says how a UH-60 Black Hawk helicopter crashed killing two National Guardsmen near Huntsville but does not say why, although the reason was determined.
www.al.com www.al.com
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“The portion of the report in which the board gave its conclusion on the cause of the mishap and the rationale for the conclusion, is redacted.”
- Redstone Rocket, which is the source for the local rag.
 
TCABM said:
“The portion of the report in which the board gave its conclusion on the cause of the mishap and the rationale for the conclusion, is redacted.”
- Redstone Rocket, which is the source for the local rag.
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The whole “closely protected and exempt from disclosure” doesn’t make a whole lot of sense. Unless classified details exist to the cause of the accident, it’s supposed to be released to the public.

Army has always been that way though. The AF will release an AIB report with excruciating details to the public but Army doesn’t play that game. They like their secrets.
 
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Yeah, I think there is more to the story.
 
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