Huey down

pmanton said:
A Huey that appears to be owned by Bell went down in Mesa AZ today. One died at the scene.
It possibly lost the tail rotor.

RIP
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Not sure about "Possibly", the T/R was found over a mile away and footage shows it spinning out of control. RIP.
 
You can fly a UH-1 and land it without the tail rotor making thrust...or stuck peddle but when parts start shedding it’s difficult but not impossible...the EP requires you enter immediate autorotation to remove torque from the drivetrain...expect a spinning pull at the bottom. There is probably no easier or or forgiving helicopter to fly with the loss of power or TR thrust...but unfortunately UH-1 non pilot seats have never had the best record for making hard impacts survivable.
 
Warlock said:
You can fly a UH-1 and land it without the tail rotor making thrust...or stuck peddle but when parts start shedding it’s difficult but not impossible...the EP requires you enter immediate autorotation to remove torque from the drivetrain...expect a spinning pull at the bottom. There is probably no easier or or forgiving helicopter to fly with the loss of power or TR thrust...but unfortunately UH-1 non pilot seats have never had the best record for making hard impacts survivable.
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I was trying to find how many degrees camber the pylon has but couldn’t find anything. Would think the entire vertical pylon has at least a few degrees offset?
 
Offset is significant...probably could have told you 30 years ago what it was...just look at a picture of a UH-1 at a hover and you can tell how it hangs on the rotor system...UH-1 was my first airframe I went through at AMOC at Ft Eustice...
 
Bell206 said:
FYI: Supposedly the aircraft had a FastFin installed so that would make the factory offset moot.
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Fastfin an attachment to the existing pylon or is it an all new vertical fin?
 
Velocity173 said:
Fastfin an attachment to the existing pylon or is it an all new vertical fin?
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It modifies the existing pylon aft of the spar and is usually used with tailboom strakes for maximum performance.

 
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Bell206 said:
It modifies the existing pylon aft the spar and is usually used with tailboom strakes for maximum performance.
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Man, never once seen a presentation that depicts a low pressure area on the left side and never even heard of Karmen Street Vortex Shedding. Good stuff.

The tail rotor interference from a tractor configuration is well known though. The Black Hawk had originally a larger tail pylon that had camber to offset torque. That was found to create too much interference drag so they cut it down smaller and put in a 7 degree cambered fin.

Seems like it would be a no brainer to incorporate FastFin into all helos...if you’ve got the $$$. I’ll take one. Well, I’d rather have a 900 hp Honeywell upgrade instead. Can’t have everything I guess.
 
Interesting...probably has a downside as well when you start shedding parts...it was common to run out of peddle in an H model when heavily loaded or OGE hover. The very reason the the AH -1 mod s was really just a G but with the tail rotor on the other side of the pylon...pulling vs pushing...and much more efficient.
 
Velocity173 said:
low pressure area on the left side
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Had heard about the the low pressure issue as several other helicopters had similar fixes but never heard of the vortex issue. From what I recall it's not an "aviation" phenomenon.
 
I still remember pointing my finger at the floor and twisting the throttle for directional control after a simulated tailrotor failure in the UH-1H.
 
pmanton said:
It possibly lost the tail rotor.
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Lost gearbox with T/R attached. Looking into aircraft loading and if engine was intentionally shutdown. Hub/blade hit L/H cockpit before departing. Bad deal all around.
 
Bell206 said:
Lost gearbox with T/R attached. Looking into aircraft loading and if engine was intentionally shutdown. Hub/blade hit L/H cockpit before departing. Bad deal all around.
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Wonder if they lost the tip cap weights on the tail rotor. We check for disbonding on the 407 for that. They’ve had at least one sling the weights and the imbalance ripped the gearbox out along with the tail rotor.
 
Velocity173 said:
Wonder if they lost the tip cap weights on the tail rotor.
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Supposedly the T/R blades are intact and still connected to the G/B. I wonder if they were light and hit the aft cyclic stop. If so lucky they didn't invert. Know of several aircraft that did after losing blades/gearbox.
 
Just saw the news report of the pilot trying to maneuver the aircraft away from populated areas. This aircraft is completely out of control. They have no tail rotor and if you’re not within the flight envelope of continued flight, you’re coming down. You either entered an auto before the yaw rate got out of hand or you didn’t. If you didn’t, you’re going to where the aircraft wants you to go.
 
Velocity173 said:
Just saw the news report of the pilot trying to maneuver the aircraft away from populated areas. This aircraft is completely out of control. They have no tail rotor and if you’re not within the flight envelope of continued flight, you’re coming down. You either entered an auto before the yaw rate got out of hand or you didn’t. If you didn’t, you’re going to where the aircraft wants you to go.
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This happens a lot when aircraft go down. Someone wants to tell the story of their pilot buddy maneuvering to avoid hitting a populated area, a school, or a bus load of kids... as someone who has been in a crash, I can tell you if you have any control, you're avoiding things that look like they'll hurt when you hit them. Your mind goes into self-preservation mode.
 
Stuck peddle, full autorotations and hydraulics off to the ground as a required maneuver on almost every annual check ride in UH-1H till it left the Army...those days are gone with twin packs and redundancy for modern helicopters...not sure if that skill set would of helped...really is a worst case scenario other than main rotor
 
Warlock said:
Stuck peddle, full autorotations and hydraulics off to the ground as a required maneuver on almost every annual check ride in UH-1H till it left the Army...those days are gone with twin packs and redundancy for modern helicopters...not sure if that skill set would of helped...really is a worst case scenario other than main rotor
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Definitely a simulator type of EP since you can’t simulate loss of tail rotor thrust in flight. Done dozens of them in the sim. Majority of the time I would’ve walked away. All depends on how realistic the IP wants to get with the failure.

One thing we do these days is a failure at a hover but we have to allow at least a 360 rotation before reacting. Adds more realism to the typical pilot’s delayed response to loss of tail rotor thrust.
 
Here's one from the old days...aircraft commander was the best in the unit, plus he had a sandbar to impact on in full auto. Walked away from it.
lost TR gearbox.jpg
 
Piperonca said:
Here's one from the old days...aircraft commander was the best in the unit, plus he had a sandbar to impact on in full auto. Walked away from it.
View attachment 85190
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My late friend Jerry had eight (!) AH-1 Cobras shot down under him and he "landed" with several parts missing each time. The most famous one was when the entire tailboom was blown off and he autorotated onto a rice paddy dike.

He became a Chinook pilot after that tour...
 
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IK04 said:
My late friend Jerry had eight (!) AH-1 Cobras shot down under him and he "landed" with several parts missing each time. The most famous one was when the entire tailboom was blown off and he autorotated onto a rice paddy dike.

He became a Chinook pilot after that tour...
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Jerry is lucky he survived to live as long as he did. Snakes were bad about flipping over on hard landings due to those narrow skids. Of course then the thing would beat itself to death. Another risk with even an upright impact is that the rotor blade could flex down and wipe out the CP/Gunner.

I was glad to fly UH-1C gunships...you go down, you have two portable M-60s onboard. Plus, your wingman could land and pick everybody up under some circumstances.
 
Video shows him descending towards the park before it came apart, and they were only a few miles from an airport t, so I wonder if there was a problem forcing a landing before the TR came off.
 
May have felt high frequency vibration in the pedals...that's enough for any helicopter pilot to look for a place to land.
 
Question for the rotorheads here. If you lose the T/R, and can cut power and initiate an auto rotation before the bird starts to spin, does that eliminate the torque problem? Does the free spinning rotor have any torque effect on the helicopter?

Just a fixed wing guy trying to figure out the physics in my head.
 
Yes, the spinning main rotor will continue to exert torque on the aircraft because the transmission is not frictionless. With good forward airspeed, you can maintain controllability due to the weathervane effect of the tailboom. If not, and if you have enough altitude, get the throttle closed, the nose down, and gain forward airspeed. The tailboom should resume its weathervane to keep you straight enough to head toward a likely spot. Then when you flare for the auto, there won't be a lot of time for the torque effect of freewheeling main rotor to kick in. At least, in theory.

Losing antitorque at a few hundred AGL and low airspeed is going to present a problem. You gotta roll that throttle off right away. Even then, autorotation in the "dead man's zone" is another challenge.

I wasn't a contact IP, so others may chime in.

EDIT: You can see the definite right yawing motion. That's from the engine still driving the main rotor with a large amount of torque. The rotor turns left, the fuselage wants to turn right. Only immediate action on the throttle would have had a chance there.
 
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midwestpa24 said:
Question for the rotorheads here. If you lose the T/R, and can cut power and initiate an auto rotation before the bird starts to spin, does that eliminate the torque problem? Does the free spinning rotor have any torque effect on the helicopter?

Just a fixed wing guy trying to figure out the physics in my head.
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Autorotation is the EP for loss of tail rotor thrust in every helicopter that I know of. However, depending on the helicopter and airspeed, it can be quite flyable to take you to a suitable area to perform an auto. They can do this by having either an offset fin or cambered fin.

For instance, the Black Hawk has a small, cambered 7 degree fin that completely offloads the tail rotor at 100 KIAS. The Bell 407 doesn’t have any asymmetrical camber but does have a fin with a 9 degree offset. So, if you’re cruising along in a helicopter at typical cruise speeds and you lose the tail rotor, you’ll get some yaw, some CG issues if it detaches, but she’ll be flyable. The vertical fin will counter the torque. If the Huey in question lost the tail rotor at slow speed, say 50 kts or less, the aircraft is going to yaw right because there’s not enough airflow over the fin. The slower you get, the more torque required, the more violent it becomes. Only thing to reduce the spin is cut the throttle and enter an auto.

If you’ve ever seen the movie Black Hawk Down, there’s a scene where the aircraft loses their tail rotor from an RPG. The PIC tells his co-pilot to bring the PCLs (throttles) off. That’s to arrest the violent yaw. If you delay, it can really get ugly and as Warlock said above, it can go inverted. Can get ugly in a hurry.
 
5A6D29D8-9C5C-4591-AFD2-4AFB09A75461.jpeg 6FC74B70-523A-44CA-9B15-30446879C1F3.jpeg Some pictures of An AH-1...I have the originals, the main rotor impacted a tree which in turn sheared the tail rotor driveshaft. Pilot entered autorotation at a very low level and went into the trees. The aircraft was impaled on a pine tree piercing the cockpit between the front and back seat. Both walked away with cuts and bruises...the full auto with the loss of tail rotor thrust was the only option...if they had kept the tail rotor that probably could of landed the thing. It crashed flying backwards
 

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That Cobra crash was one I studied in the Aviation Safety Officer Course. We learned enough to make a few changes to the way that mission was done.

Unfortunately, when the units converted to Apaches, these kind of crashes started all over again.

The pilots were not using the information in their reticles to avoid drift and backed into trees pretty regularly. One of those guys is a friend of mine who almost had to buy a few rotor blades!

The armored cockpits in the attack helicopters have saved many aviators from the results of collisions...
 
If the tail rotor and the gearbox departed the aircraft in flight, aircraft would have been significantly affected in CG. This may have affected what the pilot was trying to do with the aircraft due to control limitations ...
 
Velocity173 said:
Seems like it would be a no brainer to incorporate FastFin into all helos...if you’ve got the $$$. I’ll take one. Well, I’d rather have a 900 hp Honeywell upgrade instead. Can’t have everything I guess.
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Bell now factory installs the BLR Fast Fin mod by default on all new 412 EPIs.
 
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