Thread: Robinson helicopters - new possible rules CAA

http://m.nzherald.co.nz/nz/news/arti...ectid=11828807

Just seen this US helicopter maker rejects NZ crash report | Radio New Zealand News

Having quite a few hours in both R22 and 44 I reckon they should put a wind strength restriction on them that differs from the manual.

They can be pretty scary in anything over 25knts in mountainous areas.

But if you strictly follow procedures in those conditions they will get you home.



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Originally Posted by zimmer

Just seen this US helicopter maker rejects NZ crash report | Radio New Zealand News

Worried about there reputation, sales, being sued so they will push the blame to pilots.

Unfortunately I think there are valid points on both sides here.

Just to get this in my dumb engineer type brain.

For you clever pilot type fellas. Mast bump would come about from a negative g situation yes? like turbulence or up/down drafts caused by mountainous terrain?

Sorry if my terminology is off .

Yes turbulence, but also the main cause with the robby is large or abrupt control adjustment at high speed and light weight creating zero g on the mast.
Treated right as Dave said they are good.


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could it be that we do things here with them they were never really designed for??

I was under the impression that they were originally designed as a "commuter helicopter"

Originally Posted by mikee

could it be that we do things here with them they were never really designed for??

I was under the impression that they were originally designed as a "commuter helicopter"

Spot on. We have been told by Robinson for years that we do things in NZ they are not designed for.


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Originally Posted by Mauser308

So what happens in the case of the helo flying along straight and level and then suddenly ceasing to fly straight and level and impacting into terra firma? Do we have an issue like the Cessna's with the SIDS programme, old airframes that when given a really thorough inspection are killed off as beyond economic repair due to corrosion and stress cracking?

It just seems a bit weird that with all of the publicity of the mast bumping issues, and the causes being so well understood that we are having all of these accidents due to pilot error. The pilots can't all be just acting like muppets and getting it totally wrong!!!

Once the machine is in Low G the recovery procedure to rectify it, is a totally unnatural cyclic input to what the machine is doing.




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The aircraft affect from neg G is a right roll. well more like a really fast snap roll to the right.
The natural reaction is left cyclic. But that lead's to catastrophic events. The real recovery is aft cyclic. As R93 said....unnatural to what the pilot is seeing.
It isn't just confined to Robinsons. Any two bladed helicopter can be effected.
However.....Robinson has had many many blade failures. Both departing in flight, to cracking. There was a series of blades coming off in flight in the 90s.
For me, thats unreliable.
I will never fly one again.
Robbie lovers will give me shit. But tons crash, mostly unexplained.
Robinson will never make composite blades, or make it a 3 bladed system which mast bumping doesn't occur in as it admits to design flaw. Robbies rotor design is completely different to any other 2 bladed heli.

Happy to go into more Principles of flight to explain MB more.

Originally Posted by mikee

could it be that we do things here with them they were never really designed for??

I was under the impression that they were originally designed as a "commuter helicopter"

yes, true. Designed as a commuter heli.
But they still shouldn't break up mid flight. and small pilot errors shouldn't cause catastrophic events.

Originally Posted by veitnamcam

Just to get this in my dumb engineer type brain.

For you clever pilot type fellas. Mast bump would come about from a negative g situation yes? like turbulence or up/down drafts caused by mountainous terrain?

Sorry if my terminology is off .

This is not meant to be in any way an analysis of any of the accidents mentioned in the above posts, but will hopefully help explain what they're referring to as mast bumping.

Mast bumping is generally accepted as being caused by incorrect lateral cyclic inputs when the aircraft is in a 'negative g' situation.
'Negative g' can be caused by either turbulence, or induced by the pilot by 'bunting' the helicopter over as brads correctly explained.
If the 'negative g' unloading is sufficient enough, the thrust vector from the tail rotor can cause the fuselage to roll while the disk is in an unladen state.
The correct action is to first gently apply aft cyclic to regain the disk loading (to make the fuselages weight hang from the blades again) before any lateral (sideways) input can safely be made.
However, if lateral cyclic is used first to counteract this apparent uncommanded roll, the blades can flap excessively and possibly contact the mast with the inner head assembly at the blade root end.
Two bladed teetering systems are particularly susceptible to this phenomenon and pilots are trained to understand, identify and correct this phenomenon associated with 'negative g' situations.

I have been trained in low G recovery as much as anyone but I have no idea if I would react in a real event accordingly.
Low G according to the report took my best mate. He was a 10000 hour pilot with above average skill. He has averted several emergency situations including failed tail rotor at AUW.
Total engine failure during a climb and in a turn at 200 AGL. Yet a bit of wind got him in a R22.

I am with WW. I doubt I will ever steer one again. I have flown in winds that caused my ass cheeks to rip a bit of the seat off😆
I was flying around in an area about an hour before 2 men lost their lives in an R22 due to suspected turbulence. It wasn't pleasant.


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There are several factors that can contribute/cause mast bumping, negative g loading, low rotor rpm, turbulence, light weight & high speed & incorrect pilot inputs.

Even the most experienced pilot can't predict when turbulence might occur all the time, the problem in the Robbies is if you make the wrong input it's all over, there's no second chance. Give me a H500 any day

The two blade teetering head design is not peculiar to Robinsons.

Among those heads I've maintained and overhauled are the Bell 206, and Hiller UH12-E and Soloy conversions.

Others are any of the Bells, from the Bell 47 (Souix in the RNZAF), UH1-D ( Iroquois) and civil derivatives up to the 212/214, and the AH-1 Cobra......

Mast bump is a possibility with that head design, but none of those machines mentioned fall out of the sky with the regularity of the Robinson.

Pretty easy for Robinson to point the finger at the pilot, when for the majority of the time the poor bugger isn't around to defend himself.

Myself and another member here had first hand experience of these POS's, we were interviewed by NZCAA as the last people to ride in a well known operator's R-66 prior to its fatal crash while returning to base after dropping us into our block. The thinking was he encountered turbulence/burble going through a high pass and the disc became unloaded, the mast bump scenario. RIP Mark.

"Death on a budget" is how I've heard a high hours fling winger refer to them.

I save my hard earned and pay for the 500...

B. ( Fixer of flying objects since Feb 7, 1977 )