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Medford NJ Helo Crash

Discussion in 'General Topics' started by Pilot Fighter, Sep 11, 2017.

  1. Pilot Fighter

    Pilot Fighter Well-Known Member

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    A couple of days ago, a 269 went down killing the pilot and passenger.

    As it's being reported, the pilot reported a stuck throttle and decided to hold in a hover until equipment could arrive for possible hard landing.

    Things went bad and it went down before a landing was attempted.

    The pilot is being second-guessed for not setting down before things went to hell. I'm not second-guessing the pilot but I'm curious how difficult it would be to set a 269 down with a stuck throttle. Am I wrong to assume that even at a high throttle setting and rotor speed you could dump the collective and land? I think of many helos as being close to constant-speed props in operation.
     
    Last edited: Sep 11, 2017
  2. Inverted25

    Inverted25 Well-Known Member

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    To me the bigger question is why he was hovering over woods and not a clear area. The passenger was a famous country singer
     
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  3. Murdoughnut

    Murdoughnut Well sized member

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    Maybe he was looking for another caged bear to shoot - this time, from the air.
     
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  4. Nark

    Nark Well-Known Member

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    I don't know anything about the incident, but with a stuck throttle, I don't know why you can't land.

    I've only ever flown turbine helicopters. It's at 100% before we pull pitch (pull collective).
    Even with 120%, flat pitch isn't going to lift you off. Angle of attack, aerodynamics, you know science stuff.

    Sounds really fishy, stuck throttle, not wanting land because of a "hard landing."
     
  5. Pilot Fighter

    Pilot Fighter Well-Known Member

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    If your prey has a name, don't shoot it.
     
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  6. deadstick

    deadstick Well-Known Member

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    I believe there's a correlator (or optional governor) on the 269. With a stuck throttle, I believe if he lowers the collective the engine would overspeed.

    If that is indeed the scenario, and I hate be a MMQB, pull the mixture and do an auto.
     
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  7. dustoff17

    dustoff17 Well-Known Member

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    THIS!

    Engine and rotor would overspeed but I agree with the auto AND, especially, with hovering over a safe landing area!!
     
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  8. MikeD

    MikeD Administrator Staff Member

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    If you can get the thing held in a 3ft or less hover, then you can do a hovering auto to the ground. That said, i do wonder what relation a stuck throttle would have to becoming an accident. Stuck throttle is more a severe annoyance and possible engine limits exceedence issue if not handled correctly, generally nothing more than that. So how that went to an accident if the pilot wasn't intending on lamding, Im not certain. That said, in any helo, turning an air emergency/issue into a ground emergency/issue as quickly and safely as possible, is what most pilots try to do, with the capability of being able to have suitable landing areas quickly available for the most part.
     
  9. digduggy

    digduggy Well-Known Member

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    I had heard it was a jammed collective... Got it from a couple people I know have trained there.


    Sent from my iPhone using Tapatalk
     
  10. Pilot Fighter

    Pilot Fighter Well-Known Member

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    If I (ignorant fixed wing guy with limited rotorcraft knowledge) experienced a jammed collective my first thought would be get it down ASAP out of fear of losing all collective control and falling like a brick.

    If collective was jammed, could you set it down gently by carefully rolling off the throttle?
     
  11. deadstick

    deadstick Well-Known Member

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    Definitely interesting. I would think that, even with a jammed collective, minor adjustments to the throttle (assuming that wasn't jammed too) should allow the pilot to maneuver into position for a normal or maybe run-on landing. I seem to recall that that engine ran at something around 32-3300 RPM. Even going one mag would reduce the engine rpm by 75-100 rpm minimum.

    There has to be something else. I don't think we know all the pieces to this puzzle.
     
  12. Flyinhigh728

    Flyinhigh728 Well-Known Member

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    New reports are coming out that minutes after takeoff, he radio'ed to fellow instructors on the ground stating that he had trouble control the rpm with the throttle.

    Apparently he discussed emergency landing options and he told them he was performing a power off auto. Somewhere during the auto, the RPM decayed to the point where the blades were visible. Very sad.
     
  13. MikeD

    MikeD Administrator Staff Member

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    If he was able to supposedly maintain a low hover, a hovering auto shouldn't have been an issue. Only way to mess that up is to decay the Nr by pulling in collective pitch too early prior to touchdown. But from a low hover, even that shouldn't be something that results in a fatal accident. But....stranger things have happened.
     
  14. deadstick

    deadstick Well-Known Member

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  15. MikeD

    MikeD Administrator Staff Member

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    Even if the collective is jammed, if you can maintain a low hover (reportedly), you can shut down the engine and fall a couple of feet to the ground as the Nr decays and that shouldnt be fatal much less serious.

    If no control over the throttle but the collective is fine, same thing: either low hover auto, with shutting the fuel off or even landing and overspeeding before pulling the fuel off. Either should be quite survivable.

    So yes, questions...
     
  16. dustoff17

    dustoff17 Well-Known Member

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    A LOT of reports on this one but one thing seems consistent; high engine RPM. I, obviously, wasn't there but I'm struggling to understand the sequence of events here. Even with high engine RPM, stuck throttle, etc a low hover could be achieved as @MikeD mentioned. 2-3 feet, kill the engine and land. Several reports have the pilot at a high hover, 1/4 mile from the end of the runway and it appears the pilot killed the engine, entered auto, lost Nr and ended up 200+ feet from the runway. I'm not able to make any sense of this one..............even with a high engine RPM, a high-power run-on landing should be able to be accomplished. ACQB.........

    The only thing I can come up with is that the pilot was trying to save the engine...........

    Questions.................
     
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  17. deadstick

    deadstick Well-Known Member

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    The engine was hosed no matter what. If it was simply a throttle issue, this should have been a non-event. The stuck collective scenario would have been dicey, but do able.

    Time will tell.
     
  18. Cherokee_Cruiser

    Cherokee_Cruiser Well-Known Member

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    For someone with zero helo knowledge, the collective is the handle on the side you lift up? And the throttle is where? What's the relationship between collective and throttle? Guy above wrote if you lose collective, you'll fall like a brick? Why? Throttle won't help at this point?

    Worse case, an engine failure means auto rotation down. Why can't they do that?

    Sorry, I'm a complete dummy on helos. :(
     
  19. MikeD

    MikeD Administrator Staff Member

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    Throttle can be on the collective in a motorcycle grip style (common in piston helos), or can be on the floor (B2 and earlier AStar) or on the ceiling. Reason its common as motorcycle grip is in piston helos with no automated governing, the pilot has to be able to control the collective and throttle with the same hand....as the pilot is the manual governor. Pull more collective (change blade pitch), need to pull more throttle in, in order to maintain rotor speed. Reduce when lowering collective so as to not overspeed engine when no load (pitch) is on the blades.

    If the pilot indeed attempted a high hovering auto and shutting the engine down, thats bad juju. Best attempt hovering autos as near the ground as possible, as there is no aerodynamic assistance to control Nr as there would be in forward flight. In hovering auto, thr bird is only has what little energy is stored in the blades, and it better be managed judiciously as theres no way to get it back once used, hence doing hovering autos from very low altitude if ever possible. Sometimes, such as with logging helos, its normally not possible just due to so often being in a high hover as part of their long-line work.
     
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  20. deadstick

    deadstick Well-Known Member

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    @Cherokee_Cruiser
    It's not losing the collective that will result in falling like a brick. It's losing the rotor rpm (or Nr). You wings that generate lift are the blandes that have to rotate at a minimum speed and angle of attack to generate the necessary lift, just like an airplane. During an autorotation, the flow of the air through the bottom (going up) of the rotor system keeps it spinning, but that requires a flat pitch (collective down) or else they will slow down to a point where it's not recoverable (as some witnesses reported happening in this accident). In the airplanes, we worry about engines, but in helicopters, the transmission and associated systems that allow autorotations are more of a concern.

    An autorotation is like an sim engine failure in your trusty 172. You've done hundreds of them by the time you get your license, and they sound scarier than they really are when executed properly. That spinning rotor I wrote about earlier has potential energy. If the engine fails, the pilot must lower the collective immediately in order to retain what potential energy remains. At the bottom of the auto, the pilot is going tradeoff that rotor rpm (PE) for lift. The pilot will flare the aircraft to decelerate from 60-70 KIAS to 10-ish (this maneuver builds up lost rotor rpm, but there must be airspeed with which to do it), and this is followed by lowering the nose to a level attitude. At this point, remember the collective is on or close to the lower limit and the rotor blades are near their lowest angle of attack. With little forward airspeed, in a level attitude, at 5-10' off the ground, the pilot is going to take that potential energy from the flat-pitch rotor system and trade it for lift. This is done by pulling up on the collective which increases the angle of attack or the main rotor blades. This tradeoff will decrease the rate of descent, but this does bleed off the rotor rpm because that potential energy is a finite amount since there is no engine to drive the system and no more altitude or forward airspeed to trade off.

    @MikeD explained the throttle/collective relationship above, the earlier report that he had a stuck collective, at least according to the NTSB initial report, was not correct. That was the more challenging scenario when compared to losing the throttle control. Pull the mixture seems like an easy call, but we just don't know what was going on in the aircraft. Time will tell. Maybe.
     
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