Black Hawk crash worthiness

[Aussie Digger]

Here's a story about the Australian Army Blackhawk crash on 12 February 2004 and shows how strong the Blackhawks really are:

EIGHT soldiers miraculously survived yesterday when a Black Hawk helicopter on a training exercise crashed into a paddock in southwest Queensland.

The $13 million chopper from the School of Army Aviation at Oakey, about two hours' drive west of Bribane, was virtually torn in half in the crash which put six of the eight soldiers on board, including the trainee pilot, aged 23, and an instructor, 31, in hospital.

Witnesses reported seeing the chopper clip a tree in a paddock about 11am and fall to the ground.

"It just came down and its rotors hit the trees," said concreter Noel Forrester. "We thought, 'Someone must have got hurt in that'."

The men were engaged in military tactical training which involves flying close to the ground. They made a mayday call before they hit the ground. The crash is the most serious accident involving the Black Hawk fleet since 18 servicemen were killed when two helicopters collided in 1996.

The six injured men were evacuated to Brisbane by helicopter and remained in hospital last night.

RACQ CareFlight doctor Allan MacKillop said the instructor and trainee pilot had suffered suspected spinal fractures and abdominal injuries and the pilot also had a broken leg.

Dr MacKillop said the impact was "like dropping a car off a 30m cliff while you're sitting in it."

"It was a big crash. They were all very lucky. They were pretty stunned and in pain but they were very stoic about it."

The commanding officer of the School of Aviation, Lieutenant-Colonel Kim Jorgensen, defended the safety of the Black Hawks, saying mechanical failure had been ruled out as a cause of the accident.

"The aircraft should be congratulated," Colonel Jorgensen said. "These people have survived wholly and solely because it is a Black Hawk and we do trust it."

Australia has had a vexed history with Black Hawks, which were bought in the 1980s to replace the Vietnam-era Iroquois choppers.

In June 1996, 18 servicemen were killed when two Black Hawk helicopters collided during a night-time anti-terrorist exercise near Townsville.

In the same year, a Townsville-based Black Hawk came close to crashing when carrying then prime minister Paul Keating and staff into tropical rainforest near Cairns.

Here's a pic, I'll try and find a better one.

 

[Aussie Digger]

To clarify this, the Blackhawk was undertaking "Tactical flying" at the time and was travelling at an estimated 300Km/h...

 

[gf0012-aust]

To clarify this, the Blackhawk was undertaking "Tactical flying" at the time and was travelling at an estimated 300Km/h...

If they were Tac Flying then Iwould assume that it was the 5th AvReg and there were specwarries on board.

 

[Aussie Digger]

No I don't think it was, it was reported as being a training flight from the School of Aviation at Oakey. It appeared to be the culmination of the pilots flight training program. Not sure who the others on board were, other pilots possibly but I doubt it would be any SF operators... It's not only SF who ride on Blackhawks undertaking Tac flying. I rode on them, Chinooks and Iroquis many times flying just above the trees...

 

[gf0012-aust]

I've done tree hugging once, it was a cross between absolute exhilaration and absolute terror -

 

[Red aRRow]

Did they determine the cause of the crash?

 

[Gremlin29]

Terrain flight is what helicopter pilots live for Terrain flight is the most common mode of flight in the tactical environment for the US Army, is it that unusual for the Anzacs? The UH-60 has a tremendous amount of crash survivability built into the design. If you think this pic is impressive you should see the Blackhawk that crashed at the Paris Airshow years ago. I'll see if I can dig up a pic.

 

[Aussie Digger]

There has been some further info released about this crash. The aircraft was conducting DCA training and training to avoid "attacking" FA-18 aircraft. It has so far been blamed on pilot error whilst performing a "pedal turn". Perhaps Gremlin can help out with the specifics on that? Mechanical errors have been ruled out though...

 

[Aussie Digger]

Here's the long promised "better pic".

 

[gf0012-aust]

That is one "donalded" unit.. what a mess. There's certainly a benefit in having a titanium tub. Any crash details yet? (as in altitude it dumped from etc..)

 

[Gremlin29]

Aussie Digger, a pedal turn is accomplished with little or no forward airspeed. Pick the aircraft up from the ground to a hover, step on the pedal to point the aircraft in the direction you want it pointed in and that's a pedal turn. Typically this is a hovering maneuver. Now we do have an unapproved maneuver called an "Australian Stop" which is alot of fun. Basically your clipping along at cruise speed, drop collective, pull the nose up to maintain altitude and as the airspeed drops to around 60 knots you start to slip the aircraft sideways with the pedals which will slow you down alot faster (presenting the side of the aircraft introduces a ton of drag). Now your nose will start to swing from vertical to horizontal which will now present the rotor disk to the relative wind which is even more drag. The maneuver at it's pinnacle places the aircraft in a sharp bank and with a deft touch you will roll wings level at the point that all forward movement has stopped. Needless to say it's a risky maneuver, particularly at terrain flight altitudes which is where it's typically performed (stopping as quickly as possible isn't usually necessary at admin altitudes). It is in essence a hot dog maneuver unless your doing some serious pilot stuff to evade fire etc.

Based on the story and the pics it's really hard to determine what happened. If it was at night they could have simply pedal turned the tail into an obstruction like a tree, huge boulder etc. Since pilot error is to blame that would eliminate an engine failure. In most helicopters you can actually run out of anti-torque (bottom out the pedals) if you are too heavy, too high or a high crosswind component. 30 knots crosswind is a standard limit on helicopters but the Hawk will actually never run out of left pedal (stepping on the left pedal counters the torgue produced by the rotors, the more torgue you are pulling the more left pedal you need). Also, the standard threat avoidance for helo's when faced with fast movers is to increase the angle of attack between you and the fast mover by turning towards their nose. Looking at the pic and based on the sketchy info my first best guess is that they clipped one of those trees in the background.

 

[Aussie Digger]

The Lt Col of the Regiment, stated that the helicopter pilot was performing a pdeal turn, immediately before the pilot lost control of the aircraft and spudded in. I guess that's as close publicly as we will get to actually finding out what happened. Nice bit of ryhming slang there gf, me old...

 

[Red aRRow]

So I think Gremlin's suspicions might be true, that the rear rotor might have clipped a tree or something during a pedal turn.

 

[Gremlin29]

Something I failed to mention. Usually when a helicopter is involved in a high G crash the main rotor blades will flex down and strike the tail boom which in the pics appears to be untouched. The vertical stabilizer is gnarled on the top which also hits at a catastrophic event involving the taile rotor however that may or may not be secondary to the incident. Also, the UH-60 is the easiest aircraft in the world to pedal turn, so I doubt that maneuver caused the pilot to lose control. Finally, I'd suspect that they were performing said pedal turn rather high up rather than close to the ground due to the damage.

2 guys in my unit experienced a catastrophic failure in their UH-60-A during an instrument takeoff, 200 feet AGL and a forward airspeed of maybe 30 knots which is an unrecoverable autorotational situation, what we call the "dead mans curve" on the performance planning charts. They plowed through a row of trees and impacted a terraced field rolling the aircraft over twice in the process, it didn't look as bad as the Hawk in the above picture. All that and none of the crew were hurt, just a couple bruises and scratches.

 

[Aussie Digger]

None of the crew were too badly hurt in this crash, just some broken bones etc.