Sky Soldiers Cobra: Top Gear crash

[Brian Abraham]

Anybody with further info?

Helicopter Crash Coolidge 2012 on Vimeo

Edited to add, just learnt both crew OK and was being used in the filming of a "Top Gear Korea" program.

[SASless]

Another case of a sudden onset of intense gravity???

[mfriskel]

************************************************************ ********************
** Notice created 3/2/2012 Notice 1 **
************************************************************ ********************

IDENTIFICATION
Regis#: 197LE Make/Model: AH-1 Description: BELL HELICOPTER
Date: 03/01/2012 Time: 1811

Event Type: Accident Highest Injury: None Mid Air: N Missing: N
Damage: Substantial

LOCATION
City: COOLIDGE State: AZ Country: US

DESCRIPTION
AIRCRAFT ENCOUNTERED A HYDCRAULIC FAILURE AND CRASHED

INJURY DATA Total Fatal: 0
# Crew: 2 Fat: 0 Ser: 0 Min: 0 Unk:
# Pass: 0 Fat: 0 Ser: 0 Min: 0 Unk:
# Grnd: Fat: 0 Ser: 0 Min: 0 Unk:


OTHER DATA
Activity: Business Phase: Unknown Operation: OTHER


FAA FSDO: SCOTTSDALE, AZ (WP07) Entry date: 03/02/2012

[lelebebbel]

Cat's wait to hear Clarkeson's superlatives when this episode is released.

"Top Gear Korea" (http://blogs.wsj.com/korearealtime/2011/08/23/top-gear-motors-into-korea/) is the Korean Version of the show and isn't hosted by Clarkson/Hammond/May

[mickjoebill]

No serious injuries.

Helicopter crashes during Top Gear Korea stunt (http://news.ninemsn.com.au/world/8429475/helicopter-crashes-during-top-gear-korea-stunt)

Aftermath

ZG3pF9bNICk


Mickjoebill

[XV666]

Stills from the video:

http://i.dailymail.co.uk/i/pix/2012/03/03/article-2109632-1202547E000005DC-373_634x371.jpg

http://i.dailymail.co.uk/i/pix/2012/03/03/article-2109632-12025482000005DC-98_634x286.jpg

http://i.dailymail.co.uk/i/pix/2012/03/03/article-2109632-12025486000005DC-759_634x314.jpg

[ShyTorque]

being used in the filming of a "Top Gear Korea" program.

Enough to give the pilots "Top Gear Diahorrea" :oh:

Glad they're OK.

[rotorrookie]

Both pilots ok is what matters, the cobra is obviously very good aircraft to crash in.

[PO dust devil]

oh I see what happened.....the mast fell out..... no wonder it crashed!!!! lucky crew - thank goodness. :E

[NutLoose]

See

LiveLeak.com - Top Gear South Korea AH-1 Crash (On-Board Camera)

[rotorrookie]

those Cobra's are build like tank :ok:

[212man]

Looking at the in-cockpit footage, there seems to be a recurring theme in these recent accidents on video!

[Taff Missed]

That'd be the bit where it hits the ground.

[212man]

That'd be the bit where it hits the ground.

Yes, that tends to be a common theme to most accidents....:ok:

I was referring to attempts to reverse the direction of travel, using a vertical manoeuvre, with insufficient height....

[Coconutty]

those Cobra's are build like tank

Camera system and crew appear to be quite rugged too !

http://i34.photobucket.com/albums/d129/coconut11/Coconutty.jpg

[mickjoebill]

They crashed very close (less than 150 ft in my estimation) and on a near direct track toward the main ground camera crew and production team.
The ground shot of the car at the beginning of the clip shows a black vehicle and a camera crane in the backgound, the same vehicle is pictured by the on board camera directly in front of the cobra as it hits.

It is a very wide lens!

Mickjoebill

[henra]

Looking at the in-cockpit footage, there seems to be a recurring theme in these recent accidents on video!

That's what came to my mind as well...

That is if the camera angle is not totally misleading.
If not I have no idea how it should have sustained that apparent Angle of Bank without significant altitude loss!?
I mean the cobra is not a sustained 9g machine... :E

Besides that from the Cockpit video there seem to be no strange noises, nothing that would really point towards a mechanical failure.

Hope to be proven wrong though.

[fijdor]

At the beginning of this tread it says "hydraulic failure" and if i recall properly the Cobra has the same head and blades and some other components and I assume the same kind of hydraulic systems the B214B and the B214ST have.

If you lose both hyd systems in those aircrafts every controls seize, not much you can do except go where ever the aircraft is going at the time of the malfunction. That is probably why you don't see any reactions from the pilot in the last moment. There is nothing he can do.

JD

[Shawn Coyle]

If it's a standard Cobra with the Kaman blades, evidently one hydraulic system (of the two installed) isn't up to the job of keeping the blades where they should be.
This was found during testing by Bell of the Kaman blades, and accepted by the Army. At least that's what I remember hearing.

[Tcabot113]

fij

The Cobra head has absolutely no commanality with the 214B or 214ST.

TC

[fijdor]

You are right, Not the early models. Subsequent models yes.
but in the video it is an early model I believe.

Comparison below.

JD

http://i683.photobucket.com/albums/vv196/jacdor/IMG_0438.jpg

http://i683.photobucket.com/albums/vv196/jacdor/800px-AH-1_SuperCobra_Al_Asad_Air_Base_2164256645.jpg

[SuperF]

SC, is that cobra head, the 540 system, the same as on the UH1L/M?

from all accounts the second hydraulic system doesn't help too much, so if you happen to loose it just at the wrong point in the turn then maybe you cant get back on track and just squash in, as he seemed to do.

I didnt see too much wrong with the turn, apart from finishing a bit too low, couldn't see the balance and all that, but there is no reason why you cant have, with the UH1's at least, the line of the horizon straight up your windscreen sky in one window ground in the other, from about that height, maybe a little higher, and still pull out of it, all in balance and without pulling excess G's.

just relooked at the video, and once he starts turning, it looks like he doesn't change angle at all, so loss of control/hydraulics is on the cards...

how do those things go doing those sort of turns at full speed? I'm normally doing them slower with a load on...

[LRP]

Just a couple of observations.....I flew AH-1's off and on from 1969 - 1992 as a pilot, instructor pilot, and test pilot.
A dual hydraulic failure in this case is not impossible but highly unlikely. I can only remember one that was not due to combat damage. The AH-1G thru S Models will fly acceptably on one system, the emergency procedures are really based on a single system failure becoming a dual system failure over time, so they call for a run-on landing. With the addition of the K747 (Kaman) blades there was a problem discovered with a single system not being able to overcome the aerodynamic forces for collective settings above approximately 42 lbs (75%) torque, but there were no cyclic limitations associated with these blades. There are some single system characteristics that could influence aircraft control in a steep bank that close to the ground however.

1. For a #1 SYS failure, the pedals become very stiff as the #1 SYS is the only boost on the T/R servo. Additionally you will lose YAW SCAS.

2. #2 SYS failure, you will lose PITCH & ROLL SCAS.

3. If the power applied/required was above approximately 75%, you would be faced with an involuntary collective reduction as the "down force" on the K747 blades is quite high.

4. If this aircraft was a TH-1 variant another factor is in play with a #2 SYS failure. The front seat controls in the AH-1 have a "side arm" cyclic on the right side (much like the F-16, but mechanically linked). It made it difficult for an IP to overpower a student control inputs due to a mechanical disadvantage. A fix was developed for a limited number of airframes by adding two small servos on the right side between the front and rear seat cyclics. This equalized the mechanical advantage between the crew stations, however it added an additional characteristic in the event of a #2 SYS failure. The additional servos were connected to the #2 system only, so if the #2 SYS failed, the cyclic in both crew stations became noticeably stiff as you were having to move to small "failed" servos. This might be a factor in a low level steep turn, if the aircraft involved was a "TH-1" variant, as the cyclic would become fairly stiff at the same time that PITCH/ROLL SCAS failed.

It's been a while, but I think I got all of that stuff right :)

[Takan Inchovit]

those Cobra's are build like tank

Drop like tank, too!

[SilsoeSid]

Drop like tank, too!

Failed Air Drops - YouTube

[Takan Inchovit]

A good thing those Cobras don't have wheels. :ok:

[Shawn Coyle]

LRP:
Thanks for confirming what I'd heard many years ago about the 747 blades, and putting some numbers to it.

[LRP]

You're welcome. Had to reach way back in the dusty part of my head for the info, but I think it is mostly correct.

[whirlydude]

Interesting post

[SASless]

6EsoWpTO2qg

[Anthony Supplebottom]

Ouch squared!

http://www.pprune.org/rotorheads/478947-sky-soldiers-cobra-top-gear-crash.html

[206Fan]

SS,

I believe the posted video by SAS is a new one of the Cobra incident a year ago!

[Lonewolf_50]

Glad nobody got hurt.

Ouch. :eek:

[The SSK]

Slam bang gangnam style

(try saying that with a mouth full of peas)

[apb]

That´s a new video about the Top Gear Cobra´s accident, I posted it this morning here:
http://www.pprune.org/rotorheads/243966-rotorheads-around-world-videos-50.html#post7688231

[griffothefog]

Not an ex crop sprayer then...:E

[Thone1]

Hydraulic lock possible on the Cobra?
Although the maneuver didn´t quite seem to be this violent.

Tom

[Thone1]

Sorry, Jack stall is what I was looking for.

Thomas

[SASless]

Never flew the Cobra but if memory serves me right....there is a phenomenon that can bite you.....pitch plane coupling or something like that. Perhaps an old Dog can tell us about it.

[ron-powell]

>..pitch plane coupling or something like that.

Are you going for "pitch cone coupling"?

Operators Manual: Army Model AH-1S (MOD) Helicopter - Google Books (http://books.google.com/books?id=pXg-AAAAYAAJ&pg=PP7&lpg=PP7&dq=army+ah-is+manual&source=bl&ots=ZieyPAA4e8&sig=eycCn5XBPvL1qZLl8M9Nu2V0O7c&hl=en&sa=X&ei=B1whUdHjFubmyQG4_IH4AQ&ved=0CEYQ6AEwBA)

Section 8, page 14 describes what you're looking for under the section heading:
8-38. Pitch Cone Coupling

I agree with Thone1, the maneuver doesn't seem severe enough.

[LRP]

Pitch cone coupling is a design characteristic of the 540 rotor system. It is a result of the rotor system coning under a g-load and the flexure plate exerting a down force on the trailing edge p/c links which causes the rotor to unload itself. If you choose to, you can compensate for it by increasing collective thoughout a high G manuever. It is well known by any one with UH-1C/M or AH-1 time. I really don't think it played a part in this accident because the aircraft looked like it went nose first toward the ground, then leveled almost at impact - also given his airspeed and attitude I really don't think there was much of a load on the rotor. For my money I would say he may have had a single system hydraulic failure (a dual failure would be highly unlikely), or he just ran out of altitude and ideas while performing low altitude fancy flyin'. YMMV.