Chopper Crash At The Landing?

[Taboma]

Spent quite a few hours riding in helicopters, both military and civilian, l truly enjoy the experience.
My wife and I have made it a point with most every vacation (Not including our Havasu ones, or our own boat to Catalina of course) to include a helo sightseeing tour or two. Amazing way to really explore the Hawaiian Islands.

Of course on one trip, the elated grinning from ear to ear mood changed dramatically, when our sightseeing abruptly ended and our tour turned into one of search and rescue to find of all thing, another helicopter that had been reported to have just gone down in Waimea Canyon, on the Island of Kauai.
Didn't take to long searching the canyon to find it, laying on it's side, but passengers were climbing out looking OK, and it looked like it didn't sustain much damage.
After reporting the position we resumed the our excursion, but needless to say, that was a bit of a buzz kill reality check and everybody was ready to get back with our feet on the ground.
This was in the 90's and most of the pilots we flew with in the islands were all X-military, many having seen service in Nam and ready to give a thrill ride with just a slight nudging.
A couple of years later on our trip to Alaska we were back in the air, this time exploring glaciers, with no drama this time or since.

 

[Dirty Daytona]

Can we start some endless speculation on cause so we can be consistent with other threads? I am pretty sure they were cut off by a cigar pickle boat.

Agreed, maybe we can go on and on for days about whose fault it was and blah blah blah!!! Next will come the posts about how my uncles brothers dad flies helicopters for the CIA!!!!

 

[Ziggy]

Yes, great analogy.

With the proviso that you need to manage that stored energy, in your example the cars velocity and in a helicopter both velocity and height, in a manner that makes the ending most favorable to you and the passengers.

Used to see guys fly something they called gyro-copters(I think) where the top rotor was only a freewheel but at a slight angle fore to aft and a prop behind a seat that pushed it forward. Hang glider size thing sans wings. Pilots would give the top rotor a little swing with their hand and then accelerate forward to lift off. Akin to the current prop and paragliding deal of today.

 

[Sleek-Jet]

Ziggy, you'll also seem them called Autogyro or gyroplane. The forward motion of the aircraft provides the relative wind that spins the rotor. Some have a small electric motor that will pre-spin the rotor and shorten the takeoff roll. But in normal operating the rotor is unpowered directly.

They can't hover like a Helo, at least not a sustained hover, but can fly at relatively low airspeeds. The aircraft are more stable than a Helo and easier to fly, and offer better performance in confined areas than most fixed wing airplanes.

Autogyros have an interesting history.

 

[attitude]

Kinda like this, however I suspect the two rotors are more then enough to hover lol

 

[FROGMAN524]

Am I mistaken or was there a powerboat photo shoot some years ago where the boat hit a wave or blew over and took out the helicopter killing everybody?


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[rush1]

I bet he hit the parasailing guy right out of Thompson bay

 

[Meaney77]

Curious-how does a crash like this weather aircraft or helicopter effect a pilot, their license, insurance, career, etc?

 

[ToMorrow44]

Am I mistaken or was there a powerboat photo shoot some years ago where the boat hit a wave or blew over and took out the helicopter killing everybody?


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Are you thinking of the crash that killed Tom Newby..? Initially they thought there was contact with the boat but that’s wasn’t the case.

 

[ToMorrow44]

Curious-how does a crash like this weather aircraft or helicopter effect a pilot, their license, insurance, career, etc?

Any of these aircraft mishaps are investigated by the NTSB which will probe into any/all causative factors. Even if it’s pretty obvious it was a mechanical failure, they’re still gonna dive into your logbook, how much sleep you got, did you do a proper preflight etc. I would say the results of that investigation would determine the impact on the pilot.

 

[530RL]

Kinda like this, however I suspect the two rotors are more then enough to hover lol View attachment 925424

Those coaxial rotors are driven whereas a gyrocopter‘s rotor is free wheeling.

The purpose of that new technology is to increase the forward speed of the helicopter.

A helicopter’s forward airspeed is limited by when the retreating blade stalls. Forward airspeed requires more pitch to pull it along which increashes the angle of attack resulting in stall sooner in the retreating blade than in a lower angle of attack.

By having coaxial driven rotors you no longer need a tail rotor to counteract torque, only half of your system of lift per side is retreating at any time, and by having a prop to push in the back you need less angle of attack on the blades for forward momentum.

The result is faster helicopter without the complexity of a tilt rotor resulting in greater range, greater speed and mission profile.

 

[coolchange]

Friend crashed a r22 back in the day. Low altitude, hi temp, poor power, alarms went off. Not much power to regain rotor speed. Said it was like the world's largest weed wacker going into the trees. Lol. His Nick name is still crash today. Lol

 

[YumaRivernaut]

Is "auto rotation" basically disengaging the rotor assembly, and letting it freewheel for drag/resistance on the fall? Like putting your foot in on the clutch and coasting?

It doesn't disengage the rotor assembly from the engine. When an auto rotation has to be initiated due to loss of engine power, the pilot must immediately drop the collective lever fully down which will flatten the pitch angle of the rotor disc/blades and search for a suitable place to put down the aircraft. This stores the rotational inertia till the point of coming into ground effect just above the chosen landing spot. As the pilot nears the ground he pulls up the collective, adding pitch to the rotors from what is left of the rotational inertia and hopefully sets it down unharmed.
If the collective is not immediately dumped, the non functioning drive train would drag the rotational inertia down to a point that the pilot would have nothing to work with and at that point, mother earth rises up and smites thee in a really bad way.
Hope this clarifies.

 

[MK1MOD0]

The US Army had compound helicopters figured out by the 1970’s. Pusher props and stub wings to generate lift at high speeds. Great technology, and like already said, much less complexity and weight than tilt rotor.

 

[monkeyswrench]

Those coaxial rotors are driven whereas a gyrocopter‘s rotor is free wheeling.

The purpose of that new technology is to increase the forward speed of the helicopter.

A helicopter’s forward airspeed is limited by when the retreating blade stalls. Forward airspeed requires more pitch to pull it along which increashes the angle of attack resulting in stall sooner in the retreating blade than in a lower angle of attack.

By having coaxial driven rotors you no longer need a tail rotor to counteract torque, only half of your system of lift per side is retreating at any time, and by having a prop to push in the back you need less angle of attack on the blades for forward momentum.

The result is faster helicopter without the complexity of a tilt rotor resulting in greater range, greater speed and mission profile.

Thank you for that explanation. I knew angle of attack on the rotor was part of the forward propulsion...but had never thought of the retreating blade now effectively being in a stall. I guess I always thought of the rotors as a "screw", pulling itself up. I'd never given any thought to the rotor assembly acting as a wing during forward momentum.

 

[Taboma]

It doesn't disengage the rotor assembly from the engine. When an auto rotation has to be initiated due to loss of engine power, the pilot must immediately drop the collective lever fully down which will flatten the pitch angle of the rotor disc/blades and search for a suitable place to put down the aircraft. This stores the rotational inertia till the point of coming into ground effect just above the chosen landing spot. As the pilot nears the ground he pulls up the collective, adding pitch to the rotors from what is left of the rotational inertia and hopefully sets it down unharmed.
Because the rotor assembly cannot be disengaged from the engine, if the collective is not immediately dumped, the non functioning drive train would drag the rotational inertia down to a point that the pilot would have nothing to work with and at that point, mother earth rises up and smites thee in a really bad way.
Hope this clarifies.

In what form is this rotational inertia stored ? By the rotation of the blades ? If so, with no blade pitch, what forces is enacted on blades that causes them to spool up if they're still fighting the frictional forces of the drive train ?

 

[YumaRivernaut]

In what form is this rotational inertia stored ? By the rotation of the blades ? If so, with no blade pitch, what forces is enacted on blades that causes them to spool up if they're still fighting the frictional forces of the drive train ?

Unless the drive train is locked up it still spins freely albeit with some parasitic drag . What would bleed off the inertia the most would be leaving the collective up with pitch in the blades.
It is a combination of left over inertia from just when the engine stopped spinning the disc assembly as well as maintaining a forward flight attitude which in combination with decent, keeps airflow through the blades to keep up the rotational inertia.

 

[PlanB]

In what form is this rotational inertia stored ? By the rotation of the blades ? If so, with no blade pitch, what forces is enacted on blades that causes them to spool up if they're still fighting the frictional forces of the drive train ?

It does disconnect the rotor system from the engine. During pre-flight checks you chop the throttle to check to make sure it disconnects. Air traveling through the rotor system on autorotation keeps the rotor spinning. You control rotor speed by blade pitch via the collective.

When I was getting my private and commercial, we had a couple helicopters crash practicing autorotation's. Generally, you terminate before you get to the ground, but students getting their CFI's were required to complete an autorotation completely.

 

[YumaRivernaut]

The US Army had compound helicopters figured out by the 1970’s. Pusher props and stub wings to generate lift at high speeds. Great technology, and like already said, much less complexity and weight than tilt rotor.

 

[Taboma]

It does disconnect the rotor system from the engine. During pre-flight checks you chop the throttle to check to make sure it disconnects. Air traveling through the rotor system on autorotation keeps the rotor spinning. You control rotor speed by blade pitch via the collective.

When I was getting my private and commercial, we had a couple helicopters crash practicing autorotation's. Generally, you terminate before you get to the ground, but students getting their CFI's were required to complete an autorotation completely.

Flew a grip of hours in some really beat to shit Army birds, tried not to think about exactly how and why they flew or how many scavenged parts were keeping it airborne

My long time fishing buddy was a pilot for US Air, you couldn't pay him enough to ride in a helo.

 

[mash on it]

Unless the drive train is locked up it still spins freely albeit with some parasitic drag . What would bleed off the inertia the most would be leaving the collective up with pitch in the blades.
It is a combination of left over inertia from just when the engine stopped spinning the disc assembly as well as maintaining a forward flight attitude which in combination with decent, keeps airflow through the blades to keep up the rotational inertia.

So... like a windmill falling over?

Dan'l

 

[MK1MOD0]

View attachment 925476

One bad ass bird . I believe it was just too far advanced for the time. Sometimes the Brass is just too conservative, in the military.

 

[YumaRivernaut]

It does disconnect the rotor system from the engine. During pre-flight checks you chop the throttle to check to make sure it disconnects

Serious question. Which model helicopter disconnects the rotor system as the throttle is cut?
I'm aware of some that can be manually disconnected (not by pilot) such as as the UH-60, for ground handling purposes.

 

[YumaRivernaut]

So... like a windmill falling over?

Dan'l

Basically yes. It is wind milling.

 

[PlanB]

Flew a grip of hours in some really beat to shit Army birds, tried not to think about exactly how and why they flew or how many scavenged parts were keeping it airborne

My long time fishing buddy was a pilot for US Air, you couldn't pay him enough to ride in a helo.

I was an observer (left seat) in a Kiowa in the Army. Some of the crew chiefs working on the helicopters were better than others...

 

[YumaRivernaut]

tried not to think about exactly how and why they flew

They beat the air into submission.

 

[PlanB]

Serious question. Which model helicopter disconnects the rotor system as the throttle is cut?
I'm aware of some that can be manually disconnected (not by pilot) such as as the UH-60, for ground handling purposes.

I don't know of any that don't. If the rotor did not disconnect, an engine failure would prevent the rotor system from spinning.

Here is a good explanation of how an autorotation works.

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf

Autorotation In a helicopter, an autorotative descent is a power-off maneuver in which the engine is disengaged from the main rotor disk and the rotor blades are driven solely by the upward flow of air through the rotor. [Figure 11-1] In other words, the engine is no longer supplying power to the main rotor. The most common reason for an autorotation is failure of the engine or drive line, but autorotation may also be performed in the event of a complete tail rotor failure, since there is virtually no torque produced in an autorotation. In both cases, maintenance has often been a contributing factor to the failure. Engine failures are also caused by fuel contamination or exhaustion as well resulting in a forced autorotation. If the engine fails, the freewheeling unit automatically disengages the engine from the main rotor, allowing it to rotate freely. Essentially, the freewheeling unit disengages anytime the engine revolutions per minute (rpm) is less than the rotor rpm. At the instant of engine failure, the main rotor blades are producing lift and thrust from their angle of attack (AOA) and velocity. By lowering the collective (which must be done immediately in case of an engine failure), lift and drag are reduced, and the helicopter begins an immediate descent, thus producing an upward flow of air through the rotor disk. This upward flow of air through the rotor disk provides sufficient thrust to maintain rotor rpm throughout the descent. Since the tail rotor is driven by the main rotor transmission during autorotation, heading control is maintained with the antitorque pedals as in normal flight.

 

[YumaRivernaut]

Some of the crew chiefs working on the helicopters were better than others...

Same could be said of some pilots as well....

 

[PlanB]

Same could be said of some pilots as well....

Very true. I liked flying with some better than others. generally the seasoned Warrant Officers were locked in. The young Lieutenants just out of flight school, not so much.

 

[YumaRivernaut]

I don't know of any that don't. If the rotor did not disconnect, an engine failure would prevent the rotor system from spinning.

Here is a good explanation of how an autorotation works.

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf

Autorotation In a helicopter, an autorotative descent is a power-off maneuver in which the engine is disengaged from the main rotor disk and the rotor blades are driven solely by the upward flow of air through the rotor. [Figure 11-1] In other words, the engine is no longer supplying power to the main rotor. The most common reason for an autorotation is failure of the engine or drive line, but autorotation may also be performed in the event of a complete tail rotor failure, since there is virtually no torque produced in an autorotation. In both cases, maintenance has often been a contributing factor to the failure. Engine failures are also caused by fuel contamination or exhaustion as well resulting in a forced autorotation. If the engine fails, the freewheeling unit automatically disengages the engine from the main rotor, allowing it to rotate freely. Essentially, the freewheeling unit disengages anytime the engine revolutions per minute (rpm) is less than the rotor rpm. At the instant of engine failure, the main rotor blades are producing lift and thrust from their angle of attack (AOA) and velocity. By lowering the collective (which must be done immediately in case of an engine failure), lift and drag are reduced, and the helicopter begins an immediate descent, thus producing an upward flow of air through the rotor disk. This upward flow of air through the rotor disk provides sufficient thrust to maintain rotor rpm throughout the descent. Since the tail rotor is driven by the main rotor transmission during autorotation, heading control is maintained with the antitorque pedals as in normal flight.

So, you're referencing the sprag clutch in the transmission, right?

 

[ONE-A-DAY]

On the topic of helicopters, we live by the Havasu airport and the Marine Ospreys and Army blackhawks come in alot for fuel, last night an Osprey came over the house on approach, really low, house was rattling, went outside, the rotor blades have green lights on them, looks so bad ass at night, kind of UFO / spooky looking. I didnt get a video but here is one from youtube.

https://www.youtube.com/results?search_query=osprey+rotor+lights

 

[PlanB]

^^^ I believe most use a sprag clutch, but I was just a pilot.

 

[FROGMAN524]

Are you thinking of the crash that killed Tom Newby..? Initially they thought there was contact with the boat but that’s wasn’t the case.

Yep that's it. https://www.soundingsonline.com/news/fatal-chopper-crash-during-photo-shoot

 

[HCP3]

Agreed, maybe we can go on and on for days about whose fault it was and blah blah blah!!! Next will come the posts about how my uncles brothers dad flies helicopters for the CIA!!!!

I am here for the Navy Walrus helicopter stories.

 

[FROGMAN524]

Yep that's it. https://www.soundingsonline.com/news/fatal-chopper-crash-during-photo-shoot

I believe this is the prelim report.

https://app.ntsb.gov/pdfgenerator/ReportGeneratorFile.ashx?EventID=20070920X01418&AKey=1&RType=Summary&IType=FA

 

[WYRD]

Can we start some endless speculation on cause so we can be consistent with other threads? I am pretty sure they were cut off by a cigar pickle boat.

Pilot made a quick landing to eat some ass then grab some dinner

 

[PaPaG]

Glad all are OK.....

 

[530RL]

^^^ I believe most use a sprag clutch, but I was just a pilot.

As you point out all traditional rotorcraft disengage the engine from the rotor system. Typically as you point out a sprag clutch.

Using the pushing the clutch in analogy on a car, think of disconnecting the engine from the rotor system like pushing in the clutch on an engine that died. If one does not push in the clutch, the existing stored energy in speed is used to turn over the dead engine and as a result you don't roll very far. If you push in the clutch and disengage the engine, that drag is gone and you can coast and steer to a more favorable spot and may even have to use the breaks.

Same thing in a rotorcraft. When the engine quits some form of overrunning clutch will disengage the engine so the stored energy via height and airspeed can be used to keep the rotor system turning in order to maneuver the aircraft and cushion your "landing". Absent some form of clutch one would have to have substantial negative pitch in the rotor system to drive the engine both using up limited energy and substantially increasing the rate of descent. High rates of descent being something one wants to avoid on landing......

I pulled the R44 and the 500 flight manuals from the hangar. Here are 2 pictures from the R44 showing to check the sprag clutch on pre-flight both visually as well as the needle split you referred to.

Here is the 500 manual which refers to turning the tail rotor backwards where one checks to make sure the PT continues to spin.

Lastly this is a picture of a C20B turbine being prepared to be installed in a 500. You can see that big black overrunning clutch bolted to the engine gearbox. That overrunning clutch is just a big sprag clutch.

 

[PlanB]

As you point out all traditional rotorcraft disengage the engine from the rotor system. Typically as you point out a sprag clutch.

Using the pushing the clutch in analogy on a car, think of disconnecting the engine from the rotor system like pushing in the clutch on an engine that died. If one does not push in the clutch, the existing stored energy in speed is used to turn over the dead engine and as a result you don't roll very far. If you push in the clutch and disengage the engine, that drag is gone and you can coast and steer to a more favorable spot and may even have to use the breaks.

Same thing in a rotorcraft. When the engine quits some form of overrunning clutch will disengage the engine so the stored energy via height and airspeed can be used to keep the rotor system turning in order to maneuver the aircraft and cushion your "landing". Absent a some form of clutch one would have to have substantial negative pitch in the rotor system to drive the engine both using up limited energy and substantially increasing the rate of descent. High rates of descent being something one wants to avoid on landing......

I pulled the R44 and the 500 flight manuals from the hangar. Here are 2 pictures from the R44 showing to check the sprag clutch on pre-flight both visually as well as the needle split you referred to.

View attachment 925529 View attachment 925530

Here is the 500 manual which refers to turning the tail rotor backwards where one checks to make sure the PT continues to spin.

View attachment 925532

Lastly this is a picture of a C20B turbine being prepared to be installed in a 500. You can see that big black overrunning clutch bolted to the engine gearbox. That overrunning clutch is just a big sprag clutch.

View attachment 925534

Very good explanation!

 

[530RL]

Thank you for that explanation. I knew angle of attack on the rotor was part of the forward propulsion...but had never thought of the retreating blade now effectively being in a stall. I guess I always thought of the rotors as a "screw", pulling itself up. I'd never given any thought to the rotor assembly acting as a wing during forward momentum.

Given your natural mechanical understandings, if you want to dive into the basics of how helicopters work, here is a link to the basics for free.

Basic Helicopter Aerodynamics Second Edition An account of first principles in the fluid mechanics and flight dynamics of the single rotor helicopter

Basic Helicopter Aerodynamics Second Edition An account of first principles in the fluid mechanics and flight dynamics of the single rotor helicopter

www.academia.edu

And a power point for those that would prefer less reading.

Basic Helicopter Aerodynamics Power Point presentation

This material gives a basic aerodynamics related to rotor craft systems. This is a basic theory behind the helicopter blades. How the relative wing is affecting during hover, transnational flight, vertical flight. The theory also gives idea about the

www.academia.edu

 

[YumaRivernaut]

all traditional rotorcraft disengage the engine from the rotor system.

The engine does NOT disengage from the rotor system.
The rotor system merely free wheels on the sprag clutch.

As you point out

I think I pointed it out. He acknowledged it.
Something you purposely will not do.
But that's par for course for you son.

Edit: The sprag clutch can be in the accessory gearbox or the transmission depending on the platform/model.

 

[Dirty Daytona]

I am here for the Navy Walrus helicopter stories.

Lol I can’t talk about it, it’s classified. The CIA sealed all my records!!!!

 

[185EZ]

Not sure if it was posted but it was Mike Bradley's son, Blake, that was in the chopper crash
Fred may have been the other pilot but I can't confirm that

 

[ToMorrow44]

Want to see how the smallest shit can cause something horrible to go wrong..? Watch this. We were studying this mishap because our gearbox is nearly identical.

 

[monkeyswrench]

Want to see how the smallest shit can cause something horrible to go wrong..? Watch this. We were studying this mishap because our gearbox is nearly identical.

That was cool! I didn't know they ran planetary gear reduction systems. Learned a lot today from this thread. Not much pertains to my life, but still mechanical info for the mental rolodex.

 

[ToMorrow44]

That was cool! I didn't know they ran planetary gear reduction systems. Learned a lot today from this thread. Not much pertains to my life, but still mechanical info for the mental rolodex.

Yeah cuz the turbines are spinning 30k rpm so there’s lots of gear reductions to get it down to 355rpm (for our helicopter, 200-something for the Super Puma?)

 

[FROGMAN524]

Not sure if it was posted but it was Mike Bradley's son, Blake, that was in the chopper crash
Fred may have been the other pilot but I can't confirm that

Who is mike Bradley?


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[185EZ]

Who is mike Bradley?


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Bradley Ford/Chevrolet Lake Havasu