Bell 412 inflight loss of Collective Control

[spinwing]

We might have to ask stacey s about the 412 one eh???


From all accounts the a/c Captain also did a BRILLIANT job saving the machine ... flying it back 75 nmls from offshore to do a run on landing ....






(Unless of course I have been fed 'duff gen').

[IntheTin]

Not Duff gen Spinwing. He did a great job.

[Aser]

What the heck are we going to fly... first the aw139 tail, now this...



Something like this?:







Fly safe (if the heli lets you...)

Best regards
Aser

[SASless]

The photos beg a few questions for sure!

I sure hope the FAA/NTSB do a stress crack failure analysis on the broken bits to determine the propagation of the failure......review maintenance records and historical data for the part, chase down the lot number of the item and do an AD requiring an immediate one time inspection of all related parts. That being said....I would hope Engineers world wide would be doing it on their own as a precautionary measure.

Was there any indication of a problem seen during the maintenance action, daily inspection, or preflight?

Any history of incidents or accidents involving that part? Was there a metallurgical failure, manufacting fault, casting problem?

Big chunks of metal just do not break like that without there being a "real" cause that can be found if properly investigated?

Hand salute to the pilot for getting the aircraft down safely!

It would be nice to hear his account of the flight and the technique he used to accomplish the landing.....as it would be a very good learning tool for the rest of us.

[sox6]

I would like to here more about the 412 photos. When and where did that happen? Are they recent?

[oldbeefer]

Whew - I'm glad I've just retired

[Graviman]

From the beach wash marks it looks like the crack initiated near that central web on both sides. Unless part is resonating, i would expect highest stresses to have been near section top and bottom.

[Bespoke]

Heard from Qatar,

Bell 412 suffering loss of control on return from offshore with passengers.

Who knows more?

[Bespoke]

So its true.......... I thought this would be an aviation urban myth.Cannot find the thread though................. I did find reference to a 206 L4. How can one fly a rotory aircraft without collective? Is it something about Bell Aircraft?

[Encyclo]

"How can one fly a rotory aircraft without collective? Is it something about Bell Aircraft?"

I guess the answer could be yes; the safety design of the 412 (having the throttles on the collective) probably made the difference here.

You might have heard that the same (loss of collective control) happened to a 206L-4 a few days later in the GOM; in that case a control bolt fell out. Same outcome as the 412, all aboard unharmed.

[stickysunrise]

falling to bits?

the safety design of the 412 (having the throttles on the collective) probably made the difference here.

if the collective isn't working i don't believe it would make any difference where the throttles are!

[EBCAU]

"if the collective isn't working i don't believe it would make any difference where the throttles are!"

Could you give us another option that would allow the safe landing of a "collectiveless helicopter" that would not involve the use of throttles?

[BlenderPilot]

It also happened in Mexico about 5 years ago, landed safely, total loss of collective control. XA-TNE belonging to ASESA, and the helicopter was part of a recently purchased set of 10 412's

ASN Aircraft accident 13-APR-2006 Bell 412EP XA-TNE

[fly911]

if the collective isn't working i don't believe it would make any difference where the throttles are!

It sure would to me. But that might just be me. It's the way I learned and the way I practiced manipulating the throttles. Reaching up to the roof or down to the floor might work too, but for me at least, not as well. Point taken though.

Could you give us another option that would allow the safe landing of a "collectiveless helicopter" that would not involve the use of throttles?

Reduce altitude by increasing airspeed, use power pedal and uncoordinated flight (slip) to aid in slowing airspeed before touchdown, find a long, wide hard surface runway with crash equipment, anticipate runway friction to slow you down after initial contact, anticipate ground effect and the possibility of becoming airborne again, be ready to cut power by fuel or throttle(s). Burning off fuel before landing will make you less likely to burn, but should be weighed against lighter and consequently faster landing speed. Use a crosswind / headwind combination to allow you to use more power pedal to rob more main rotor lift. If at altitude, consider that OGE hover requires more power than forward flight. An OGE hover may be a way to lose altitude, but may require you to shuffel in and out of settling with power on the way down. Settling will reduce your altitude but could get out of control if allowed to progress too far. Remember, you can't reduce collective to aid in recovery and must rely on airspeed only to come out of settling. All of the above, by the way, is if your power settings are too high, such as in cruise flight when collective is lost.
If on the other hand you lose collective in a reduced power scenario such as in a decent but still have sufficient power to maintain some forward flight and maintain altitude, your landing might be considerably less challenging.

[Bespoke]

Thanks

Sandyhelmet, Thats very Interesting that this is an event that is trained for, am I correct that the pics on the 206 thread are indeed 206 pics and you train for component failure?

Fly911, your explanation seems very involved compared to sandyelmets, have you actually experienced this failure?

Blenderpilot, I checked your link and it doesnt actually mention the collective from what I see.

[Thud_and_Blunder]

Must be a Bell thing - ISTR a ROPAW 214ST having a similar experience with an equally safe outcome not long after it entered service in the mid-80s.

[SASless]

Duiring the Vietnam War....a US Army UH-1H aircraft crew found themselves confronted with the absolute worse case scenario of "stuck collective"....that being the collective stuck at the maximum up position.

The aircraft was in the process of taking off from a "Hot" LZ....took numerous bullet hits from hostile forces....and upon reaching a safe altitude...discovered they could not lower the collective.

They were able to fly the machine to an airfield and landed it by means of reducing Rotor RPM. The old Huey with its amazing strength coped with the situation quite well.

As to location of throttles....it is of no matter as the left hand is going to be free to manipulate the throttles and not be required to move the collective. I have done the maneuver in Bell type helicopters and Sikorsky S-76's.

A thing to remember....as you decrease Rotor RPM you will find the Tail Rotor begins to lose thrust as well making the Pedals less effective.

It is truely a balancing act in multiple parameters.

[Bespoke]

Thanks

All has become much clearer now that the thread has become whole I appreciate that as a novice my comprehension of the problem and the means to solve it is unclear. An instructor has mentioned that the rotors would be free flying and have the ability to change angle depending on the loads applied and would make the control of the machine vague with variations of rotor speed and flight speed.

[stickysunrise]

is pilot a ppruner? would appreciate his/her insight

It would be nice to hear his account of the flight and the technique he used to accomplish the landing.....as it would be a very good learning tool for the rest of us.

hear hear SASless

[fly911]

Bespoke:

Fly911, your explanation seems very involved compared to sandyelmets, have you actually experienced this failure?

Well, Sandyelmets explained the process using throttles but no collectine.
I was answering the following question by EBCAU:

Could you give us another option that would allow the safe landing of a "collectiveless helicopter" that would not involve the use of throttles?

No, I have never run into this situation while flying thankfully.