Helijet S-76C Loss of Control November 2015
 

BC operator Helijet had a nasty incident last November with one of their four HEMS S-76C.

Shortly after uncoupling the AP at 600ft on night-time finals the crew got into a high rate of decent (between 1100fpm and 2500fpm, depending on who you believe) and allegedly lost so much NR that the generators went off-line. They did however manage to recover but the casualty they were flying to pick up had to wait for a fixed wing transfer the next day.

More details here.

The paramedics union are fairly grumpy about it.

The generators (DC) are driven by the engines not the rotor, the AC genny is driven from the MGB but there is only one of them, so I take it they mean the AC generator. Old age has taken away the memory of the Nr that it it drops off line at, sorry.

The AC Generator drops out if the NR falls below 93%.

Thanks. Sorry for being imprecise. Its been a few years since I had anything to do with an S-76!

When the AC drops off, doesn't the invertor take over?

Forgive me but the generator status is surely the least interesting matter.

A RoD of between when uncoupling the AP at 600ft and over torqueing the drive train in the process seem more significant to me.

I doubt much that they care
 

I doubt the 2 paramedics on board cared much whether it when out at 92% or 93%
They where to upset to continue even doing there job. The patient sure did not care. They had to stay alive until a fixed wing with more paramedics could come to get them.
The issue is how could this happen, then on a go around, happen again.
Then two days later, when everyone has settled down and the aircraft is "fixed" it starts off on another medivac and returns before take of because of a bad vibration, which ultimately saw the transmission and gear box changed.
The company said the fire the 2 pilots.

Of course it wasn't "fixed" first time. Wonder why.

A single operative inverter can power all the AC buses, except for the monitor bus. Only the AC generator can power the monitor bus. The AC generator will only power the AC buses if both inverters are off-line. The AC generator automatically drops off-line when the engine-out logic is tripped, as determined by N1 and ECL position. NR is not used in the logic to determine engine-out status. In an emergency if you droop NR below 92% with both engines operative the AC generator should still drop off line.

Sounds like they got into VRS... at night and on final to what was essentially a black hole with a ring of flares.

Can't imagine a more terrifying situation. Glad no one was hurt.

The report says they were on final to the Tofino airport (runway), is that not true?

Yeah, but to my knowledge it's unlit and the staff set out a flare ring. I could be wrong.

Correct. RNAV 29 in Tofino, completely unlit. O Dark 30 medevac, very high ground to the east, black hole approach. Sounds like a lot of no fun.

My thinking with these approaches: there is no need to decouple the AP at DH/MDA once visual, even if you have to subsequently manoeuvre for a circling approach to land. With a stable approach established on the final segment the AP will keep you stable and going down to the runway, just maintain IAS minimum for coupling (what is it, 50 knots?). When pilots decouple too early from a stable approach and then move the controls is when things are at risk of getting unstable.

At 600' the search light provides adequate illumination to see the ground ahead of you. Passing 50' decouple, trim 10 degrees nose up, the airspeed and sink rate will reduce, run it on at 20 knots using a touch of collective at the bottom to cushion it on. There is no need to move the controls at all, just trim! With 5000' of runway ahead of you there is no need to slow down too early and risk getting yourself in a sticky situation. Anyway, this is the technique I teach, maybe there are other safe ways to do it. But the important thing is to use the resources available, maintain safe airspeed to be assured of reaching the runway, and monitor the sink rate. You will not get into settling with power if you keep 30+ knots airspeed, however be mindful that you can quickly slow below 30 knots and get into strife close to the ground if somebody is not closely watching the parameters.

These are my thoughts, for what they're worth.

Are nvg used in this part of the world? Great sa tool off the bottom of an approach and in this case may have been a huge help?

NVGs are an option.... should the government decide to pay for them, as its a provincial contract.

Gullible, It appears that 29 was unlit so that means no landings on the runway. Have to land at the "flare ring" laid out for them.

Does anyone know where the flare ring was laid out? Was it on the runway or was it on the ramp?

I question the decision (pilot or operator or CAA) to do a black hole approach to a blacked out airport when according to my dog-eared VFR Flight Supplement the hospital has a perfectly good helipad with good approaches, floodlit ambiance, lead-in lights, pad perimeter lights, lit windsock, and the ambient cultural lighting of the entire town surrounding it.

I've seen that stupidity in Africa where you would ignore the huge floodlit ramp area by the hangars to go land 1/2 mile away on a pitch black runway lit with some feeble dying pot lights, thought Canada was smarter.

I believe the Tofino Hostpial pad is day VFR only nowadays.

Tofino pad is closed permanently! Airport is the only option.