Bell 412 inflight loss of Collective Control
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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').
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').
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.
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.
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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.
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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?
"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.
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.
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falling to bits?
the safety design of the 412 (having the throttles on the collective) probably made the difference here.
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"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?
Could you give us another option that would allow the safe landing of a "collectiveless helicopter" that would not involve the use of throttles?
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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
ASN Aircraft accident 13-APR-2006 Bell 412EP XA-TNE
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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?
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.
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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.
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.
Last edited by Bespoke; 29th Jul 2010 at 13:50.
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.
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.
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.
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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.
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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
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.
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Bespoke:
Well, Sandyelmets explained the process using throttles but no collectine.
I was answering the following question by EBCAU:
No, I have never run into this situation while flying thankfully.
Fly911, your explanation seems very involved compared to sandyelmets, have you actually experienced this failure?
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?