An angel at my pad (Keck hospital rooftop crash)
 

Thankfully no injuries and the organ they were transporting was still useable.
Thankfully it didn't fall off the building.

Anyone know how it ended up on its side?

https://www.dailynews.com/2020/11/06...pital-helipad/
https://cimg5.ibsrv.net/gimg/pprune....e19344f4c1.png

skadi

Looks like a TR drive failure from the witness video

another angle

https://www.liveleak.com/view?t=9PUrn_1604775586

I'd agree that looks like a T/R drive failure at the most critical stage of the landing. Looks like a quick and correct response by the pilot, namely by lowering the collective, bearing in mind there was little or no time to shut down the engines. Quite interesting to see how rapidly it rolled!

Glad to hear they all survived.

The second video classed it as a "hard landing"!

I was wondering whether the pilot had induced the roll in trying make sure of reaching the roof whilst yawing. Hard to control attitude and track once the yaw has developed.

Got it where it needed to be, all lived 👍

Sure that this was a TR drive failure? I saw a longer video of the approach and the TR RPM didn't change during final and beginning of the rotation .

skadi

Is this the same heli type that crashed in Leicester two years ago and if so, could it be the same issue?

The Leicester aircraft was an AW169. This was an AW109.

T/R rpm looks steady..maybe los of tail rotor authority...what is the Density Alt etc?

If it wasn’t a driveshaft failure it must have been a hard right pedal input, or control runaway. It’s difficult to tell if the tail rotor rpm changed because we’re not watching in real time and camera frame rate masks what’s going on.

As per the previous post, the aircraft are totally different types (169 versus 109) and their tail rotor control systems are totally different.

Golly, you guys must be subject matter experts on the 109 Series TR Control system to be so sure of what happened.

DA pretty much sea level.

Yep - just watch the video and pull up a comfy armchair.....

The initial slow rate of rotation at loss of directional control does not look like sudden TR drive failure to me.

have you seen the video in post 4? I wouldn’t call that slow - it’s gets real busy real quick!

It wasn't slow by the time it got to complete the first 360, but the rate of rotation for the first 90 does not suggest to me sudden TR drive failure.

Having carried out a ‘Check A’ on the 109 every working day for the last decade and a half and having over 3,000 hours on type, I do have some idea of how the thing is put together.

One other “gotcha” on this type is that out of the two hydraulic systems, only #1 boosts the yaw servo. If #1 hydraulics drop off line, servo assistance is lost and the pedal feedback forces can be very high. It’s then very difficult to apply enough “boot” to keep the aircraft straight at low speed. The normal way to land in that condition is a running landing at about 30 kts, ideally with a crosswind from the left.

Going by the strange (oil) mess on the helideck, this makes the most sense.

I wonder how that's going to be removed? It's a long way up. A bigger helo to lift?

If I had been involved, that might have been wee.

The crashworthiness of that aircraft in the second video is quite impressive, it really did hit the heli-pad quite hard on its side which is not where the best impact cushioning for the occupants lies.

I've not flown an AW109, and like Alpha-Romeo's I don't seem to fit in them very well, but I'm told that unlike say an AS350 they are quite benign on the piano pedals through most phases of flight. Can the pedals also be operated without power assistance much like an AS350?

Did you read Shy Torque’s post?

Yes, just trying to compare the effort required with something I already know.

Thanks to you both for the answer(s).

I flew a Squirrel ‘N’ for three years or so. The hydraulics out pedal feedback forces are definitely a lot higher on the A109 and there is no accumulator, unlike that of the Squirrel.

The tail rotor blade pitch of the 109 is designed to revert to a neutral setting without hydraulics. However, to move them from that setting you have to use so much foot force on the pedals (to get limited effect) it feels like something is likely to bend or break.

The good news is that the aircraft remains flyable in most circumstances, provided that it doesn’t happen at very low speed!

Thanks ST, much appreciated.
Any horn (Fiat?) go off if you lose that hyd circuit?

No need.....the flashing master caution light and the kick in the pedals are clue enough! The horn on a Squirrel is there because the hydraulic accumulator gives you a few seconds to sort your life out.

The RFM advice for the 109 advises a slow reduction to 90kts and not using any AOB greater than 25*. It also warns against flight regimes needing high control inputs.....

If this is what happened here, it just wasn’t the pilot’s day. At least they all escaped major injury, or worse.

The #1 Hyd fail approaching the hover is something I regularly train on the A109 FFS. It is controllable, but you have to recognise it quickly, and give it a seriously hard load of left boot. If it takes you by surprise, it could easily give you a rapid right yaw before you can react.

Given the modest amount of damage to the aircraft, and that there were no injuries, the basic cause of this surely has to be known by now. Particularly for those of us that fly 109s, the most important thing is having this info asap so at least we/maintenance can know if there is anything that needs extra attention. Thankfully mechanical failures are very rare, but, if it was one, this could easily have had been an accident of as much tragedy and sensation as the Leicester 169.

You have me by 2 years. I only have 8 years on the 109/119 series. As a licenced mechanic doing line and heavy maintenance. It's a pretty basic and very reliable TR system. The TR itself however is a maintenance hog with the Teflon bushings wearing out pretty quick depending on how many cycles/hour you do. Keep it shimmed and keep it tight and it will last. Unlike a Bell, the TR should NOT teeter easily on the trunnion. It should take a good push with the palm of your hand. A TR that teeters like a Bell is worn out and is probably going to cost you many $$$ to sort out.

Nooby, two years? You missed out the other half decade but I’m always grateful for an engineering point of view. ;)

I wasn't including drinking days. LOL.

Normally if Leo is concerned about the aircraft they would have communicated as such by now. But it is still silence. Which would SEEM to indicate that all was well with the aircraft, or at least that it wasn't a design/manufacturing defect.

Did NTSB issue any report on this accident?

Googling show there's an initial factual one - http://data.ntsb.gov/carol-repgen/ap...ort/102246/pdf

Nothing further.