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"Why Robinson helicopters seem to have a bad habit of crashing"

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"Why Robinson helicopters seem to have a bad habit of crashing"

Old 7th Mar 2019, 19:01
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"Why Robinson helicopters seem to have a bad habit of crashing"

Interesting recent article from New Zealand.

https://www.noted.co.nz/currently/so...abit-crashing/
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Old 7th Mar 2019, 21:17
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I've never flown teetering rotor, so I have no experience or knowledge on 'mast bumping'.

So, from my perspective, this design appears un-airworthy, if it is true that encountering turbulence can cause mast bumping leading to loss of control.

Can someone educate me?
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Old 7th Mar 2019, 22:04
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All two bladed, teetering designs are susceptible to mast bumping. UH-1, 206, R44, R22, makes no difference. Get into low or negative G's with these machines and those like them at your peril.

People like such machines because they are economical to build and operate, and require less storage space.

Clearly, being the smallest and lightest helicopters of this type, the R22 and R44 are going to be more susceptible to external conditions that could cause unwanted low-G conditions, i.e. it takes less turbulence to cause a problem in an R22 than in a 206 or UH-1. Similarly, the R22 and R44 will be more susceptible to ham handed pilots.



Last edited by aa777888; 7th Mar 2019 at 22:43.
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Old 7th Mar 2019, 22:48
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Robbie bashing in 3-2-1 here we go again
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Old 7th Mar 2019, 23:02
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Innocent question from fixed wing PPL who has had the odd pole around in an R-22 and even made a miserable attempt or two at hovering.
Is it possible to have a non-teetering two bladed main rotor?
If so, if Robinson wanted to change to that kind of rotor - would it require a fundamental re-design of the aircraft?
Rather than them simply being shite - I thought the high rate of crashes in Robbies was due to a machine that was originally designed pretty much for point to point commuter type flying - being used by pilots in quite aggressive flight regimes - like hunting or stock herding at low level - which it's not suited to.
Low G flight, hard sharp turns or rapid reversals of direction etc.
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Old 8th Mar 2019, 00:20
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Its the Indian, not the arrow.
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Old 8th Mar 2019, 02:22
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Originally Posted by tartare View Post
Innocent question from fixed wing PPL who has had the odd pole around in an R-22 and even made a miserable attempt or two at hovering.
Is it possible to have a non-teetering two bladed main rotor?
Not as far as I know. See also this explanation.
If so, if Robinson wanted to change to that kind of rotor - would it require a fundamental re-design of the aircraft?
People have often postulated a three-bladed, fully articulated Robinson rotor head. It would be a major redesign.
Rather than them simply being shite - I thought the high rate of crashes in Robbies was due to a machine that was originally designed pretty much for point to point commuter type flying - being used by pilots in quite aggressive flight regimes - like hunting or stock herding at low level - which it's not suited to. Low G flight, hard sharp turns or rapid reversals of direction etc.
Only the low-g stuff is a problem. Other than that the machine is quite agile and really very fun to fly without ever putting it into a low-g state. Again, it's an issue of someone putting the machine into a situation that allows it to be in a low-g state. Don't do it advertently. As the article cited above said, use the right tool for the job. When it's 30 gust 50 out a two-bladed machine is probably not the best tool, and a lightweight two-bladed machine is an even worse choice. It's the inadvertent scenario which is the nightmare, say a sudden penetration into unexpected severe turbulence at speeds around max. cruise. Such scenarios are more likely in mountainous, windy conditions. Under such circumstances one must fly conservatively, with a good understanding of mountain winds, and be ready to slow down instantly in the event of turbulence.
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Old 8th Mar 2019, 02:23
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would it require a fundamental re-design of the aircraft?
Yes. The Robinsons were built to a price point, originally intended to cost $22,000.

The teetering head is hugely successful in the Robinsons and Bells. It can be sturdy, and is the simplest way to get a rotor head onto a helicopter. If you wanted to make it non-teetering, the price will rise considerably, mainly for the complexity and testing. It cannot have any movement in the lead/lag plane or the imbalance would tear it apart. It can have flapping freedom, and of course feathering. But in the decades of rotorhead development, nobody has made one successfully. Stick with the teeter and the wee-waa and the desire to stay alive with positive g.

This thread is named for the propensity for low-time pilots to take the R22 and others out of their design envelope, with resultant tears and gnashing of teeth.
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Old 8th Mar 2019, 03:48
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When it comes to 2-bladed helicopters, there is only one that continues to blame pilots for in-flight breakups, especially inexperienced pilots, yet many accidents have included people that don't fit the profile.
There is only one that puts notes in flight manuals to significantly reduce speed in turbulence.
One that publishes safety notices to remove controls so pax can't bump them and to shift blame to the pilot.
One that requires extra training to deal with the safety nuances.

They can be flown safely but the ability to leave the safe zone seems far too easy and doesn't end well.
When you build to a price you can't engineer out problems and the target market seem willing to accept the compromises mainly because they believe that accidents only happen to other people.
Will take an old JetBanger any day ahead of the alternative.
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Old 8th Mar 2019, 11:06
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Will take an old JetBanger any day ahead of the alternative.
What? Even with it's dangerous mast-bumping teetering head...?

Methinks there is more to Robbo accidents than the head design, somehow.
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Old 8th Mar 2019, 12:04
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Lets put an end to this "Mast Bumping" is a Mortal Sin thing.....it is an issue for sure but then so is any number of other issues for other designs.

Take one look at the number of flight hours for the Bell 47, 204, 205, 212,214, including Military models all. using that style Rotor Head system....and I would suggest Mast Bumping is one of the least notable causes of accidents.

Yes...you can do yourself in if you allow the factors that cause Mast Bumping to occur....but there lies the central issue....the PILOT!

Robbies do the Mast Bumping thing because the tolerances are so much smaller than that on a Huey....and the same is true for the Bell 47 compared to the 212 or 214.

That tells me that one has to be far more judicious in choosing the conditions and manner one flies the Robbie than the larger better built aircraft.



Note: The US Army fleet of UH-1's accumulated almost Eight Million Flight Hours during the Vietnam War....and many of those same Huey's are still flying today in the Civilian Market.

Add the other militaries in the USA and around the world, and civilian operators and the total fleet hours are well beyond Ten Million Hours and counting.



That is not Robbie Bashing....that is just the plain ol' truth.

Since I am even thinking about Robbies....I shall go have a couple of double Cheeseburgers with a large order Fries (Chips) and a large Chocolate Milkshake.....to ensure I cannot fit through the door of a Robbie.


https://vtol.org/files/dmfile/50-52H...rdinkSO162.pdf
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Old 8th Mar 2019, 12:18
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And wasn't the 206 the safest single-engined aircraft in the world at one time?
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Old 8th Mar 2019, 12:30
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It was....and that included airplanes as well as helicopters.
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Old 8th Mar 2019, 12:31
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And although other helicopters can experience mast-bumping, only the Robbie has pitch horns that break under the strains of the flapping - that's if the blades haven't impacted the tail boom or the cockpit before that happens.
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Old 8th Mar 2019, 13:01
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Adding the coning hinge for a little extra flapability was also a stroke of genius
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Old 8th Mar 2019, 13:23
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From 2006 to 2016, looking at US data only, the NTSB records 67 fatals in Bells of all types, 66 fatals in Robinsons of all types. And we know that the fleet sizes are nearly equal in the US between the two makes. We don't know exactly how many hours each fleet does each year (but I would like to). So absent any reliable fleet hour data, if you are flying in the US it really doesn't matter if the name on the side starts with a "B" or an "R", except that it costs twice as much per hour to operate even the least expensive turbine machine, R66's included, and much more than that to operate something with at least four seats and at least three main rotor blades. At that level of cost differential, whether it's wholesale or retail, people will happily accept more risk to get in the sky in a helicopter. Except that the stat's say there really isn't any more risk one way or the other.

Now if you are flying in a country with a name that starts with "N" or "B", all bets are off!
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Old 8th Mar 2019, 13:41
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a7&8, you keep raising this as means of a justification, and like I have pointed out previously, when those Robbies are flying HEMS, fire, police, agriculture and many of the other high risk activities then you may have a point.
Until then, Joe Soap flying from A to B and some occasional news coptering won't account for the similar fatalties, not withstanding the vast difference in seating capacity of the types.
Just waive the white flag and admit it is what it is - tin foil and some rivets held together with duct tape and bubblegum
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Old 8th Mar 2019, 14:00
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Not giving in, BR. The same points could be made about the high risks of primary training and high risks of carrying around low time pilots, both primary missions for Robinsons. The case can be made that both fleets are engaged in higher risk activities, each unique to themselves.

And I still want to see some trustworthy fleet hour data. I'm beginning to suspect those numbers are either closely guarded secrets or just nobody is bothering to track them. If someone can show in a verifiable way that the Bell fleet is flying twice the hours of the Robinson fleet, then I'll go slink home with my tailboom between my legs. But not until then.
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Old 8th Mar 2019, 14:41
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From 2006 to 2016, looking at US data only, the NTSB records 67 fatals in Bells of all types, 66 fatals in Robinsons of all types.
A simple quote of a factoid is of zero value in any analysis or discussion.

Let me ask a few questions then you get back with us.

How many Robinson crashes occurred while doing EMS flights at night?

How many Robinson crashes occurred at Night doing Air Taxi flights?

How many Robinson crashes were pilot error in daylight operations within sight of the home airport (like training, etc.).

How many Robinson crashes occurred while carrying underslung loads to include Fire Fighting?

If you are going to throw out a simple number....that will not buttress your argument much at all.
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Old 8th Mar 2019, 15:32
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The R44 is the best selling helicopter in the world, why? Because its more affordable (and has a back seat) to more people. Why is it more affordable? Because its light. The lighter the aircraft the more delicate you must handle it. Either accept this limitation, or go fly something else,...but stop your bitching!
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