Helicopter accidents that are due to "mast bump"
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- Опубликовано: 3 окт 2024
- Helicopters with semi-rigid "teetering" rotors such as the R-22 and R-44, can be subject to "mast bumping" under certain conditions. This can be fatal. What is it and how to prevent it.
Robert Mason wrote an excellent book about flying choppers in Vietnam called "Chickenhawk". It impressed upon the reader that pilots and choppers were a very delicate balance of man and machine, and knowing the machine precisely made all the difference.
As a fixed wing pilot this was very well presented and it explained why so may R-22's have crashed . Even mountain flight instructors in fixed wing aircraft fall victims to down draft accidents .
Former OH-58 driver here. Spent a lot of time at tree top and very low level (
Thanks for the info!
Great hello.
Most reliable in the world.
Only rival: OH-6 (hope you agree)
OH-6/MD500 has a fully articulated rotor system though, so why would you need to get it loaded?, you can to full cyclic pushovers in them without worrying.
@@serdavosseaworth6115the original post said he was flying OH-58 helicopters. I believe the first variants had a two blade teetering rotor system (same as a Bell 206) and later variants received the four blade articulated rotor system that was then used on the Bell 407.
great video, one of my biggest fears and hesitancies when flying a robbie, but as long as you don't exceed its capabilities, its a great machine. just slow down to 57-70kias in turbulence, minimize cyclic inputs as much as practical and do not control altitude with your nose attitude.
Good comment
As with all things, operational limits should never be exceeded
These helicopters are also notorious for deadly survivable rough landings due to poorly designed fuel tanks that rupture and trap you in a burning mess. There is a 60 Minutes documentary about this killer- the company runs from the cameras and their liability to this day.
Stay away from them.
Helicopter: Ten thousand rivets, flying in formation.
Only approximately.
That’s very optimistic
I fly the R44 in my training and went to the Robbinson safety course. It is unfortunatly not a good aircraft to fly in the mountains/ moderate to severe turbulence. But I also think keeping in mind that the R44 is the most common helicopter in the world so it will seem like it crashes more than lots of other helicopters but in reality its just the most common heli in the world. The second most common heli in the world is the Bell 206 and it also is suseptable to mast bumping as well, so it is not a Robbinson only problem. The recomendation from robbinson is to always slow down and if winds get bad, land the damn helicopter. Weather can be dangerous to all aircraft but helicopters have an amazing ability to land anywhere! I have 150hrs rn with most in the R44, it is a very simple and safe helicopter as long as you understand its limitations, like all aircraft.
I learned (via a series of expensive self-taught lessons) about rotary wing aircraft by flying RC helicopters in the days before sophisticated flight stability electronics were common. It took me about 6 months just to get to the point of being able to reliably hover in a relatively fixed position, and each of those early flights would end with sweat covering my face from the intense concentration it required. I've never flown an actual heli, and I'm certain I would never want to. There's an old adage that goes something like "a helicopter is a collection of random and dissimilar parts flying in tight formation". And, I might add, that's only on a good day.
dissimilar and fatiguing parts.
I fly both, and it is easier to fly the real helicopter!
1000 hours of CE time in Hueys. Around 1990 we got mast bumpers made of rubber to avoid these issues. Many of our pilots were former Viet Nam pilots and saw the results of mast bumping. The Cobras were especially prone to mast bumping due to the birds attack mission. Why it took so long to get the rubber bumpers I don't know but our pilots were very aware of what caused a rotor system to break off and avoided such manuvers. I never felt unsafe with our military trained pilots and incidents of mast bumping.
The sad fact is the less experienced pilots tend to fly the tricky lower cost machines.
Same with rc Planes/Helicopters the bigger expensive ones are way easier to fly... its like wtf why i started with the cheap ones
@@Chevdriver It depends...
@@Chevdriver To be fair that's a nice thing with RC where the only thing that gets hurt is money while someone is learning and they will be a better "pilot" thanks to it, can't exactly say the same about the real things.
Another x-perrt
I worked at RHC as a flight test mechanic, mast bumping is a known issue with these helis, there are callouts in training for this issue on what and what not to do. We used to receive a few helicopters back to the factory that were battered from mast bumping.
Robinson R22 Lightly Loaded. Does he mean G load or low GW of R22. Becouse when it comes to GW of R22 there is no such thing as lightly loaded. It barely has enough power to TO with two people and 40% fuel on slightly warmer then std day at sea level. Othwerwise I can see how mast bump in fast fwd flight can occur. The pilot is pushing R22 to near its Vne, the cyclic os almost fully fwd. Then turbulence hits and for a moment R22 is at 0 or negative G and mast bump occurs. The excess flap either slices into canopy, damaging blade, or slices off its boom . Without boom, even going into immidiate autorot, chances of survival are slim to none. R22 and R44 are delicate gossamers of helicopter world.
Excellent video and thanks a lot. I've only been in a helicopter twice in the army. A scout and another who's name escapes me. I know it could deploy swingfire missiles. The wing control mechanisms fascinated me even though I was an electronics tech !
Mast bumping is like an automotive engineer telling a driver: our cars will turn 30 degrees in each direction, but, don't ever move the steering wheel more than 25 degrees going downhill at speeds faster than 3 miles per hour or catastrophic failure can occur. That scenario is just as ridiculous as mast bumping, and is garbage design and engineering, plain and simple!
That was my thoughts too. You'd have to be slightly unhinged to buy and fly a machine like this? The more I read about helicopters, the more I realise how complex the engineering is and aerodynamics are, and therefore how many failure modes it has.
Helicopters built like cars, fly as well as cars.
Bullshit. Its akin to driving a car in reverse at high speed on a bumpy road when you go over the top of a hill in reverse at high speed and wonder why you roll over and disintegrate.
I have flown real planes and fairly large scale RC planes (5 to 6 foot wing spans), the latter well enough to place in the top 2 or 3 in most competitions, but I can't wrap my head around flying an RC helicopter with all the inputs (cyclic, collective, throttle, etc.). I've had friends who had large scale RC helicopters, with me on a buddy box, and it doesn't take me but just a few seconds to get out of shape to where the owner has to quickly take over. It was quite frustrating because I thought I understood the science but could never stay ahead of it. That said, hats off to those who can.
My wife’s first husband was killed in a UH1H helicopter. There was a severe mast bumping incident, the mechanics replaced the rotor and mast. A couple weeks later, the transmission came out while inflight.
Sorry! This explanation enhanced my distrust of rotary wing aircraft! Sorry! I'm fixed-wing certificated since 1989, have owned 4 certificated and 1 experimental fixed wing, and have difficulty trusting a 'collection of several thousand moving parts flying in loose formation'. I could be totally mistaken, but I'm also still alive after almost 35 years of fixed wing flying.
Some things are meant to fly, and some things have to be made to fly.
Often the Al Gore Rhythm serves up trash. Today it pointed me to this site, a treasure! Could be because I watch blancolirio? There are old pilots, and there are bold pilots, but there are no old, bold pilots! I've subscribed, from Western Australia.
SFAR training. And flying the aircraft within its envelope and limitations.
Any pilot who does their planning and knows the conditions of their flight can determine if there will be turbulence. And can then be prepared using all the above to avoid or recognise the conditions that can lead to Mast Bumping or low G situations.
An aircraft will perform the way it is supposed to perform and designed to perform. If it is knowingly operated outside the envelope, you're putting yourself at risk. Game capture, mountain frying or flying into turbulence, and continuing the flight are examples of deliberately putting yourself at risk.
Guns dont kill.... people using guns kill.
Just my opinion. No disrespect to those who know or have known others who have passed in accidents.
While I was undergoing helicopter training in the 1980s, Robert Noyce, the CEO and co-founder of Intel Corporation, came into the FBO for a demonstration flight. The chief flight instructor took him out over the hills south of the airport in one of the school's Robinson R22s and after a rather short flight returned with a couple of notches in the rotor mast, the result of demonstrating a low-G pushover. They were very lucky. A few more rotations under those conditions would have severed the mast. Noyce never came back for a flight lesson.
Well that wasn't a very noyce thing to do.
Woah, and Intel may not have been the company it is today.
The POH for Bell 206 JetRangers limits the operation to 1/2 G positive. Going less than that risks a mast bumping incident.
I learned in a Bell 47. I have tried to find any cases of mast bumping on them, because it can’t. It was built two Sprague cables that limit the movement of the blades on the teeter hinge. It reaches the limit before it can mast bump. The R22 is a bad design. Frank Robinson worked for Bell. He should have known this. I think he did everything he could to eliminate weight or anything he thought superfluous. To make his helicopter lighter and less expensive. That cutting corners costs lives.
Now knowing this, I don't understand why mast bumping possibilities couldn't be engineered out of every helo.
EXACTLY!!!
More uneducated nonsense. the R22 and R44 are great helicopters, the problem was and remains a failure of instructors to be taught how to teach properly this important subject.
Accident rates are very low with properly trained pilots,
fact is most training is below par to this day.
Got my private in 1970 in a Cessna 150. Love flying.
Never had an opportunity to even ride in a RW much less fly one.
After listening to your presentation I am damn glad I never got that itch.
I left out my usual language regarding ever being caught dead getting in one! //ji
Nah you would have been right ...
Boeing Vertol makes incredible aircraft.
My opinion, too. Got my licence in a PA18 (1970).
another uneducated noise
That was a very informative and easy to understand video. Thanks for that.
As a novice idiot in the helicopter world i can say that these machines are way more sophisticated to fly than they first appear to, the complicated mechanism enabeling flight explains the higher incident rate compared to an airplane, the upmost respect to these pilots
I hear you.... To call yourself a "novice idiot" is to already recognize that there are gaps in your understanding and you are willing to learn ..Thus avoiding "We couldnt tell Him anything he didnt already know itis" Well Done You !!
Both a Helicopter and a "fixed wing" are "Aeroplanes" ..i.e. they are neither Balloons or Zeppilins. Engine failure in wooded country in a fixed wing ...you are most likely dead ..In a Helicopter... provided the pilot can do a forced landing ..you wil very likely live.
There is nothing more or less inherently dangerous ...nor more or less easily understood ...with a machine that is mechanically simple or one that is mechanically complex.
Perhaps by way of further elucidation .. say you have electric trim runaway on a slippery but bog basic kit plane.. you cant get to the circuit breaker to diable it (not sure which one it is") and have never really considered trimming with a manual mechanism (if it has one) ...couldn't be simpler ...but only marginally survivable. I hypothetical I hope makes the point. Simplicity is not your friend... You still have to know what you are doing.
If by “higher incident rate” you mean crashes due to the complicated nature of helicopters, this is a general fallacy. The main reason is that helicopters can and do much more risky work than nearly all fixed wing craft (I say nearly, as firefighting, for example is also done with fixed wing).
Got my commercial in a 22, if the disc unloads it starts to roll and you just gently pull back and reload, then regain back your heading and that's all.
Now I understand why my dog tilts his head when I try to teach something to him
Back in 1985 I took 5 lessons in the R22 and the instructor never mentioned mast bumping.I wonder if boom strikes can happen,it happened to me with my model R/C helicopter.I could imagine it would be a disaster in a full scale helicopter
Having seen the interview with the NZ companies CEO and learning a thing or two, you'd be reluctant to step into a 22 or 44....
Hard to know Michael. If flown correctly, a well maintained machine should be safe. My friend was very experienced yet came to grief and all the answers are still not in. Regards.
Been trying to get my ex to go up in one for years
Hmmm. Having witnessed a Robinson (fatal) crash, I will likely never go in a helicopter again, but definitely not a Robinson. Fuckin' death traps. If the company is aware of problems in their design, why not address them? (Just by the way, and to be sort of fair, the accident I witnessed was engine failure followed by collision with power lines in the auto-rotate landing.)
@@jordancoleman2402 Lol!
Having been trained by the RAF on the Sycamore helicopter in the sixties, I am aghast at the cavalier handling I see so much these days. Helo design has improved over the years but the basic vulnerabilities of the helicopter remain and sensitive handling is a must at all times. They are NOT sports cars nor jet fighters and the stresses involves in these extreme manoeuvres are just asking for trouble.
There are helicopters sports cars like the Red Bulls or the Apache.
The semi-rigid one is incorrect, there's no mention of the dampeners, the disk and mast will still end up at about 90 degrees to each other, this video could lead to confusion, it implied that the helicopter fuselage remains level, that is NOT true.
I've never been in a helicopter as a passenger let alone wanting to fly one. I'll never forget hearing from a very experienced metallurgist in the Aluminium Industry his description of helicopters as being 'flying fatigue machines' especially with reference to Aluminium rotor blades. Joy flights? Perish the thought !!!
What can be done if there is a main rotor separation, of not just enjoy the ride for the next few seconds until impact?
You’d likely die from a broken neck even before the impact.
You would never ever get me in a chopper!
Every 2 bladed rotor system is comprised in a low G situation.
No mention of the trusty old Jet ranger here.
I love Robbie’s, they are genuine workhorses that have built many a business over the years.
If private pilots had to complete commercial licenses to fly , the problem would almost disappear.
They call the nut at the top of the UH-1 rotor mast the "Jesus Nut". If you mast bump, it's "BYE BYE ROTOR! HELLO JESUS!"
As an experienced airplane pilot, (same as fixed-wing), I'm afraid I would instinctively push the stick forward if I was about to collide with a bird at about eye level. I'd bet that was the cause of some of the mast bumping accidents.
Most likely the cause of the R44 crash in TX about a year ago. Commercial fixed wing pilot on a Rotor lesson with a very low time instructor, and they're thinking there was a very abrupt cyclic imput by the student, chopping the tail of the R44 off. So, so sad!!!
With 1000 hours in R22s and 1000 hours in fixed wings all I can say is that there are flight envelopes in every aircraft type and flying outside them can end in disaster whether it’s an R22 or a Cessna 172. We know what they are and how to avoid them. Blaming the aircraft for a pilot doing stupid stuff just drives noisy know-nothings to demand the aircraft type be banned. Pretty soon there is no aircraft at all allowed.
@@scotabot7826 That's not mast bumping according to this video. But I've heard about this scenario with Robinsons several times, usually fatal.
@@Jabiru430VHDODYes, but there are degrees of everything.
If the Cessna 172 was designed so that a negative g push over was likely to break the wings off, would you consider that an acceptaple flight envelope limitation?
Don't dive the airplane to avoid a bird strike. It is the birds natural instinct to fold its wings and dive to avoid hitting you. Diving the aircraft puts you both on a collision course. A climbing turn is a better method to avoid a bird. Its amazing how many times I have seen a bird at 3000 feet AGL!
Maybe its a naive question - why don't Robinson include a freewheeling sleeve of some kind at the point where the blade impacts the mast during a mast bumping scenario. Seems a cheap fix...
The tetter hinge is not as you explained it is underslung to prevent lead and lag, as the blade flaps up it moves out by action of tetter hinge e.iminating lead etc
UH-1 B
Flight manual...
"Avoid evasive maneuver"
We all know when these birds were active.
" and that's all I got to say about that"
The main cause for low g conditions is north likely to be severe turbulence rather than cyclic pushover, although that still happens too.
Why can't the rotor articulations be limited in range of motion to avoid mast bumping?
For it to be beefy enough to stop it, it would signifigantly increase the weight of the rotor system making it lose a lot of performance, which is also dangerous for helicopters as-well. Helicopters are very light weight and in high altitude/temperature situations it would barely be able to be operated, if not at all. All semi-rigid rotor systems have mast bumping. The two most popular helicopters in the world use it: the R44 and the Bell 206 due to its much less exspensive operation compared to rigid and fully articulated rotor systems.
No way I would ever set foot in any Robinson helicopter. Would rather go by mosquito ultralight helicopter
Helicopters are safe... when parked in a hangar during maintenance.
Very interesting, is it not possible to design the system so the rotor cannot physically touch the mast?
Well that chap did show us the rigid system - which apparently works well with fibre glass blades on the Red Bull machine.
@@DrTWGI think he means a limiting mechanism of some sort to not allow the angles to get severe enough
This is my first thought too. If you're driving a car and turn the steering too far in eiter direction,. the tyres of the front wheels can rub on the bodywork. Except they don't because manufacturers prevent that happening by simply setting a limits to the travel of the steering angle. Ironically these are called "bump stops".
@@MadScientist267the rotor could bump the limiting mechanism, so it adds up to the same thing
No its not possible, the forces are too great.
Think of it like a bottle top opener popping the lid off a soft drink bottle, the rotor system does the same thing to the mast in an instant.
It's the sudden and very rapid roll to the right due to the tail rotor forces that the pilot then instinctively inputs the large cyclic movement to the left with the rotor disc unloaded, game over from this point your rotor system has departed. The correct action when a low g situation is encountered and ensuing rapid roll should be aft cyclic to load the rotor disc then correct the roll all in an instant, easier said than done but if you want to live that's what needs to happen.
hard to trust this guy when he looks like hes broadcasting from heaven
Great video thou I would add the link to Jacob's original video to your video description.
Dumb question - why are helicopters not engineered so that limits cannot be exceeded with the cyclic causing mast bumping?
Robinsons mission was to build affordable helos. Its main rotor system is the lowest cost system.
Thank u for the video. I wonder if the recent fatal R-22 accident in New Jersey was due to a mast bumping
And so I fly gyrocopters instead. low g and uncontrolled blade flap is still a thing i have to avoid but dives and zoom climbs can be done with proper technique without falling out of the sky or crashing into the ground.
I'd offer these ideas to African Home Copter Builders.
Leading a horse to water comes to mind no matter what country ....
I had mast chugging in a descending left turn like a bucking motion for no reason it happened I entered auto Rotation and the bucking got faster but the upset disappeared slowly
Still to this day I think there is a hidden issue in Robinson Rotor head design.
Sounds like a bit of slop in the swash plate.
No mention of the simple fact that a strong enough rain storm on the disc could also force it down ....
Sadly anything that is man made and rides on air is a risk.
Mitigations can be taken, but unfortunately all lessons are learned though trial and error.
Error can be fatal.
Life can leave you faster than you can appreciate it. So stop. And thank yourself for existing.
Helicopter accidents are due to the fact that God does not think they should be able to fly either. Autorotation is something you do to fool the passengers into thinking there is a chance you might survive. :)
Thank you I will never perform these manuvers
I know i will get some hate for this comment. I will never ever get in a Robibson helicopter. Jet Ranger any day...NEVER A ROBINSON !
Those things just continuously fall out of the air.
Good video, but you are confusing Coriolis Force with Coriolis effect. The two are not interchangeable.
Yes, true.
Really interesting
Great educative video. Thank you. Three bladed rotor would do. 🧭
I am a Navy veteran and retired Army 1SG. One of my duty stations was at Ft. Campbell, KY with the 160th SOAR. It became time to re-up and my company commander and 1SG allowed me and accompanied me aboard an MH-47 Chinook. Re-enlisted at like 7000 feet. Was the best reenlistment of my career. Hoooooah! 🫡
Is the mosquito rotor prone to mast bumping ? 🤔
The Mosquito XE series helicopter is capable of mast bumping like any semi-rigid, teetering rotor, but not necessarily prone to mast bumping. Avoid Low G maneuvers and turbulence.
If students were taught to cancel updraughts by use of collective rather than set a power a lot of accidents could have been prevented
Unfortunatly a lot of people learn to fly in places that don't get very much turbulence so they don't get training on it.
Robbinson helicopters are not a friendly helicopter unless you are aware of thier characteristics. The rotor mast is to high ,the blades are to inconsistant when being manufactured and if you get rubber mounts for the main rotor mast that are to soft you may just end up dead from the freqeuncy that gets created in the mast. This freqeuncy tears the machine apart and blade to cab strikes will occur. Nice flying machine if you no what your doing but if the freqeuncy manifest the main rotor mast you better only be about 50ft off the ground and land right away,shut it down get out of the machine and watch it vibrate till the rotor stop completely.
Really, so you would order Robinsons to be scrapped right? More uneducated nonsense
Robinson.....motorcycle..on heaven...foff..
In my experience I’m a CW4 retired a semi head if you mast bump well before that happens usually you’ve removed the tail nice explanation though also if you mast bump your just spent a lot of money
I suspect they hit a powerful Willy Willy that threw them into strong negative G, with mast bump inevitable.
One of the strong theories Brian
R22 and r44 are both dangerous helicopters.lots of crashes
Guys , as far as I understand, very high turbolance can induce problems to the rotor.
I’m I correct? So flying in a valley in strong winds could be dangerous.
I’m I correct?
yes, it can throw you up and over, as if you are driving over a hill top, thats low G
Showing my ignorance here as not a pilot, why is there not a mechanical limit so mast bumping can't happen ? Could some one explain why it is not mechanically blocked so as not able to cause interference ! Thanks
It wouldn't do much good. Mast bumping in a Robinson R22 happens a few inches from the pivot point, driven by blades that are about 12 ft from root to tip. Thus, the leverage is *_huge,_* so much so that there is no material that could withstand the pressure at the point of contact between the blade hub and the mast. The notches in the mast get progressively larger with continued bumping until it breaks, or the pivot bolt shears.
See my comment above. My question exactly.
@Milosz_Ostrow thanks Milo for you explanation 🙂
I was thinking along the same lines, thinking of a maybe a ball or roller bearing mechanism.
.The purpose of the hinge is to relieve stress applied to the hub, mast and blades. If you limit or reduce the amount it can travel you are limiting the amount of potential stress relief and also limiting maneuverability. In most cases it is not the mast that is severed, but the long heavy blades of a two rotor helicopter that continue to droop even after hitting the mast. This movement most often allows the rotors to hit the tail or even the cockpit. So to recap, by limiting the movement you would just induce stress earlier, while the blades would continue to droop. This is why good helicopters are fully articulated. Semi rigid is only used because it is the CHEAPEST option. In saying that helicopters with fully articulated rotors have cut off their own tails also, just much more difficult to do.
Ha, I clicked the 1000th like
Excellent!
Ohh my gosh, this old man lost his daughter
I think the R44 is less prone to mast bump.
The R44 is worst due to a more powerful tail rotor moment
I never knew!! 🤦 👍
You fly in a Robinson long enough you will die
Excellent1
Thank you.
Rangers love push-overs 🤥
Try sitting in the same room as the microphone rather than the next street 😡😡
Sound quality has improved...See latest videos.
Helicopter accidents
Excelente.
Flying death traps
🥱
I've attained approximately 4500 hrs in rigid rotor copters. And the other 18k in other types. The most rugged design by a longshot is rigid. Very, very stable. The BK-117 was the best 👍 The Bell 222 was very smooth, but still had the 2 per beat. The AS-350 B2 was powerful and smooth, but still subject to ground resonance. I could go on, but no need. When I talked to a couple of FAA examiners one day, they both relayed to me their distaste for the R22 design. I trusted their opinions. 🦜
What sort of a load will hit the rotor after the zero g portion of the curve you showed. Steve
1:55 Where's the link?
this video appears to be mostly a repost of someone else's.