Black hawk down -
 

Although I am among those who generally mourn the loss of any fellow airmen I muss say in this occurence I will not be too sad


Question: how hard would it be for reasonable competent helicopter pilot to fly an UH-60 ? And given a the fairly wide use around the world outside of US supervision how hard would it be to get training ?

Hello, ZD:
The 1976 fly-off competition between Boeing and Sikorsky took place in several places.
The operational evaluation started at Ft Rucker Alabama and was completed at Ft Campbell.
The Army assigned 10 pilots to Boeing and 10 to Sikorsky. They were selected to represent the wide spread of background and experience that reflected the Army pilots who would be flying the winner.
We instructed the 10 pilots who would fly the Sikorsky UTTAS ( what the aircraft was called at that stage ) according to a syllabus that I had written. They got one flight at empty weight and the rest was either at design gross weight ( 16,400 lbs at the time ) or alternate gross weight ( 19,900 lbs at the time ), and external load of 7000 lbs. Syllabus included all the AFCS/SAS failures, OEI failures etc.
We signed them all off at the 10 hour point and from then on, they flew the evaluation by themselves. There were no pilot error issues during their operational evaluation flights at either location.
(To my knowledge, Boeing did something quite similar )

I wonder if Brother Dixson just finished a covert assignment instructing the Taliban Pilots with video proof of some of the techniques he taught them?:ok:

Wire strike?

Maybe 212. Hard to say much from that short clip. At one point you can see a bunch of aft flapping over the nose and I looked to see the stabilator angle but couldn’t determine with any certitude. The S-70 has 25% more hinge offset than the S-61, thus a lot of main rotor control power ( hub moment ). One assumes those aircraft were delivered with all the maintenance pubs etc, but I’ve no idea what sort of maintenance training if any, had yet been put in place.
The following comment dates back to a Persian Gulf marketing trip with a team from Westland in the 1980’s, but a general impression in those countries was that while piloting had substantial status, maintenance work had the opposite and thus they had difficulty interesting young men to become helicopter maintenance qualified. Maybe different now? Don’t have any contact with folks who dealt with the Afghanis in this area.

The mishap obviously startet way above all powerlines:

https://fb.watch/fva2HYLllB/

skadi

That video makes it look like a TR drive failure of some sort. Or maybe a servo hardover.

Thanks to skadi's longer video, I'll offer a guess: tail rotor, or tail rotor drive, malfunction.
(aah, I see crab's got the same idea)
For Mr Dixson: would a jammed right pedal, or a servo runaway, result in something like we see in that video?
For some reason, I vaguely remember that the design of that system (unlike some others) between boost, SAS, and trim allows one to mitigate a trim runaway by disabling either SAS, trim or both.
Will see if I can find the old notebook, memory very hazy.

As I look at the first video, and mentally paste that end result to skadi's video, they appear to have been flying over a populated/built up area.

Playback on large screen mode and .5 speed: it appears that the TR is slowing down BUT video quality makes it very, very difficult to be certain. It does seem to indicate, however, that neither power was reduced nor that any attempt was made to enter full autorotation.

OK, it's definitely not the pilot's fault, it was LTE, which we all know applies to every helicopter ever built. Not.

To my simple mind, a T/R driveshaft failure would have had a much faster snap into the spin, rather than the slower build up to roll coupling shown in the film. As stated above, the only pilot effort to get out of it was right at the end where the nose suddenly poked down.

LW, it doesn’t behave like a tail rotor servo hardcover: they aren’t going very fast at all and that tail rotor has a lot of thrust….what I’m saying is that at the speed in the clip, a servo hardcover would result in either a ship going sideways or if slower than say 45, doing a spin around the main shaft axis..
There was one fatal accident at Ft Bragg, which comes to mind and was caused by a failure to safety wire a nut in the mixing unit ( collective to longitudinal limiter ) after maintenance was done there. Nut finally backed off and dropped into the limiter effectively preventing the pilot from moving the cyclic rearward.
The clip starts with the nose down at a pretty substantial angle, especially for the altitude. Any info as to what the flight path was prior to that clip coverage?
As to the SAS boost or trim failures, if one just reacts and flies the controls normally, you’ll never come even close to the attitude where that clip starts.
Did you ever hear about the UH-2 fatal at Kaman where ( I recall being told by an ex Kaman pilot ) the heel of the CP’s shoe/boot got stuck in the hole in the floor where the cyclic was? This one makes me wonder about issues related to pilots “stuff” getting in the way of things. One of the pilots getting up to change seats with a guy sitting in the back and their flight suit or similar getting caught on the cyclic? Early in the 53A program a USMC crew was flying x-country on a winter night in the SW USA. The combustion heater on minimum was too much and one pilot took off his flight jacket-it caught the cyclic, pulling it aft, then it freed itself and snapped forward ( other pilot not on the controls ) making the main blades take a divot out of the cockpit roof, displacing the engine throttle quadrant but not enough to affect the engine power. Close call.

Should have seen the five seconds prior to the last video, at the very start it seems to have some forward speed, that could make a TR driveshaft failure not appear as dramatic as if in slow speed / hover. They probably do not have access to dots and spares, so fly until it break?

Here's a longer version of the crash!

https://www.instagram.com/reel/CiX35...d=MDJmNzVkMjY=

Edit: I just noticed Skadi posted the same footage above!

Thanks. There was a seahawk accident in 89 at North Island that began with the aircraft at about 100 kts straight and level, between 300 and 500 feet, and the TR thrust failed ... took the crew a bit to figure out the trouble since at that airspeed there's some streamlining, then as they slowed it began to swap ends after they ran out of pedal. They took off pitch, did the 'not quite an auto' cut gun and ended up with a very firm landing just south of Point Loma in the water. (Pilot in left seat got knocked out when his forehead hit cyclic, Right Seat pilot lived (seat full stroke, but still plenty of back injuries) so 'got the engines off a little high' is probably what happened and why they hit the water that hard.
From the surviving pilot's various briefs, the nose movement (slow at first and then pitch becoming in issue rather soon) reminds me of what we see in skadi's video - but their situation is complicated by being near/over a built up area. The Seahawk guys were over water so the "auto now" response was (from our training) more or less done once they realized "loss of thrust" -- had they gotten the engines off a second or two later, both of them might have gotten out.

As I watch this video, the increasing amplitude of nose pitch suggests to me that the power (or some power) was still on, even if reduced from forward flight, as the pilots were not confident in an auto as the answer and tried to fly it down to the ground (and avoid the dwellings in the foreground).

But that's a guess; could have been other stuff going on.

LW-Just had a look at the Skadi clip-actually, 4 looks. Hard to say with 100% certainty, but I "think" the tail rotor is slowing down when you get about halfway to the ground. As to why they lost it in the pitch axis-hard to be sure. Couple of things in my mind, but would be pure speculation. Main rotor looks to be at 100% all the way. NAS Jacksonville had a tail drive failure ( later found to be a tail pylon disconnect coupling maintenance issue), and in fact one of the pilots had been in the NAVPRO Office at Stratford doing acceptance test flights on the production models. Did a nice auto to calm seas and all were picked up quickly. Their problem did not initiate in a hover or close to it. and they had the altitude to get things in order.

Losing the pitch axis could well be just down to disorientation from being spun around - again speculation.

Well....we can look forward to the AAIB (Afghani Accident Investigation Board) Final Report in a few weeks time that will answer all of the questions.

No disagreement there.
FWIW, Tail Rotor on the Blackhawk, when all things are going well, provides about 2.5% of overall lift.
If John's estimate is correct on the TR beginning to slow down, that incremental loss of lift back there (with a substantial moment arm) would likely contribute some pitch instability.
Good point. This crew apparently did not (but that's a guess, video's have limited frame of reference).

Preliminary report from said AAIB states probable cause as 'loose nut at the controls"

Just a sad loss.......... of a Black Hawk

Interesting kit-setting of the MRB, not in the same league as the T-72 turret but not a bad effort. Quick maths, the drivers have about 0.6g longitudinal acceleration from the waltz, with that, how easy is it to get to the PCL's on the UH-60?

Pretty amazing that the machine takes that long to get out of sorts with loss of T/R, guess the hinge offset is helping the driver maintain a semblance of control, most other machines will be out of control completely early on with the feedback of the cg-hub offset. U guys did a fine job on the UTTAS, J.D.

FDR, thanks…..but we both and all owe thanks to a Colonel Bud Patnode and the group he headed up circa 1970 and came up with the handling requirements for the UTTAS. The hinge offset increase and matching cyclic control range resulted from a couple of things, but among them was the requirement to land on a slope of 12 degrees at any angle to the slope, and to land on a slope of 15 degrees at 90 degrees to the slope, both left and right. BTW the 12 degrees up and down slope capability existed for both most forward and most aft center of gravity loading at design weight.
( the Army built appropriate slopes at Shell Field, Ft Rucker and we checked out our 10 young operational pilot evaluators on those slopes-those pilots had some fun with that, but basically, except for the wheels and brakes, the same principles they had been taught for the UH-1 held true. )

There was some interesting initial fallout from the hinge offset increase, within SA engineering and flight test:

Folks might recall the first Skycrane, the S-60, which was basically an S-56 power train and control system on a new crane-type fuselage. There was some internal concern about the higher control power ( hub moment ) with such a machine, which had a much lower inherent fuselage roll inertia. The concern was whether with very heavy loads the resultant control sensitivity would lead to a serious over control tendency. No worries….we will do a flight test to examine same. ( this all happened before I signed on but the folks involved were still around to tell about it ). So they fabricated some sets of controls to incrementally increase the sensitivity and started testing. Initial results weren’t showing much of an issue so a decision was made to go to a 50% increase in sensitivity. Pilot Ed Mullins put it this way when telling me about it: “ John, the moment I picked it up into a hover, I knew we were screwed “
( Now the S-60 had a pair of R-2800 P&W engines running on 115/145 fuel ). The ensuing crash on the flight field at Stratford would have been fatal for both pilots, but the cockpit broke off and rolled away from the fireball. Both pilots were Ok and soon back on flight status.

With that background, and the increased hub moment vs roll inertia of the UTTAS, we used the flight simulator at UTC Research CTR to evaluate this area. Now mathematically the numbers did not look like there was a problem…but I crashed every time in that sim…..and so did the Ch Engr Pilot and the Ch. Pilot., so we cut down the roll control sensitivity for the first hover of the UTTAS ( UH-60A )-it was not even close to being an issue-and put the control range back to where it should have been and is today, for the second flight.
Explains my skepticism re sim based decisions in future years. ( and yes-that was a “ Gen-Hel “ based sim program ).