Don't assume anything

Nark said:
I'm digging in the recess of my brain. I can see the device, but I can't remember the proper name... Spline gear?


Edited to add:
After a 15 second look in the -10, it's called a free wheel unit. (2.41.1)
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Roger - but the terminology isn't the issue. The free-wheeling unit doesn't disengage the rotor from the transmission, it disengages the engine from the transmission. As you know from doing autos, the rotor is driving the transmission which is why you get nice things like AC power - those spinning blades are spinning that transmission. If the transmission seizes, you are straight-up effed as it is directly connected to it. There is nothing that disconnects the rotor from the transmission except for material failure. See the description of this accident as an example: http://www.imeche.org/news/engineering/crash-helicopter's-gearbox-'failed'-with-tragic-consequences
 
MikeFavinger said:
Roger - but the terminology isn't the issue. The free-wheeling unit doesn't disengage the rotor from the transmission, it disengages the engine from the transmission. As you know from doing autos, the rotor is driving the transmission which is why you get nice things like AC power - those spinning blades are spinning that transmission. If the transmission seizes, you are straight-up effed as it is directly connected to it. There is nothing that disconnects the rotor from the transmission except for material failure. See the description of this accident as an example: http://www.imeche.org/news/engineering/crash-helicopter's-gearbox-'failed'-with-tragic-consequences
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You're right. For whatever reason, I was thinking the input module came after the transmission, rather than a link between the highspeed shaft and tranny.

Which makes sense when the EP calls for collective adjust only enough to establish a decent with power remaining applied to the main transmission during the descent.
 
Yup. That's why it's a Land Immediately. Normally a power-on landing, as autorotation isn't required, and often making minimal changes in power so as to not cause further stress to a transmission that is out of oil and could seize at any time. But the big deal is, get on the ground yesterday. Because when that transmission seizes, so do your rotors.
 
Cherokee_Cruiser said:
And your only indication is an oil pressure gauge? Rotor RPM gauge? No vibration or anything physical to show abnormality?
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Transmission oil pressure caution light, temp light, and transmission chip lights all with associated master warning lights. It would be really, really obvious.
 
MikeFavinger said:
Transmission oil pressure caution light, temp light, and transmission chip lights all with associated master warning lights. It would be really, really obvious.
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One problem we have, IMHO, is people who fly aircraft who have zero mechanical knowledge. Maybe they can't separate the difference from a needs service light on their reverse osmosis water filter and oil pressure, oil temperature warning lights on an aircraft in flight.

Show me a guy who can't get you a 3/8 drive ratchet with a 1/2 socket and 6" extension and I'll show you a piss poor pilot.

I'm flying with a CFI friend of mine in the VFR pattern. He's low and slow, adding power on base. We roll out on final and he adds full flaps and increases the power some more. I asked (couldn't help it) and he says he always adds full flaps when he rolls out on final. He didn't have enough mechanical to understand how his actions were affecting the aircraft.
 
@fholbert I understand what you are saying, however in this case, that is not the case.

Also I doubt very much that Capt Sullenberger is able to change the tire on the A320. Perspective goes a long way.
 
SpiraMirabilis said:
How many of us have had the pleasure to fly "hangar queen" aircraft that have "well known issues" or quirks with perhaps a gauge or other similarly benign sounding issue?

http://www.marinecorpstimes.com/sto...aused-fatal-marine-helicopter-crash/74288256/
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I didn't take my assigned tail on my fini-flight because the "fuel pressure low" light on the #2 engine kept coming on 10-30 seconds after I pressurized the fuel lines as part of the "Before Starting Engines" checklist. Per the checklist, the lights only needed to go out after pressurizing and confirming the associated boost pump light came on. But seeing as how the same bird had a motor flame out due to a fuel line coming loose only a week prior and forms so full of write-ups it became hard to keep track of them, I elected to make my last flight in that bird the one prior to this.

As others have said, helicopters are the mystical ladies of the flying world. If you pay attention and really listen, they'll make every dream come true. You ignore her for a second, she'll take everything you've ever held dear.
 
Chip lights or tranny overheats/low pressure. On the ground now, whatever that ground is.

Freewheeling units, sprage clutches, overrunning clutches, and the like are meant to disengage the transmission from the engine, not the rotors from the transmission.

A helicopter is a loose collection of parts flying in close formation around an oil leak. All those parts want to go in different directions, and if there is no oil leak, you need to add oil.

Richman
 
Sad.....RIP

This reminds me of the ATR crash in Taiwan. Both this crew and the ATR crew had knowledge of a previous MX issue that seems to have clouded judgment and actions. Seems to me, these accidents would not have occurred had it NOT been for that knowledge.
 
Without wishing to besmirch the memories of the two dead aviators, I do not understand their postumous promotions. The reports seem to make clear that the flight should have been survivable and that they did nothing heroic to save others in the vicinity of the crash. I grant that virtually no one would choose this method of gaining rank, but the lesson would seem to be reward for messing up.

Slightly analogous to the WW II habit of naming airports after local pilots-in-training who crashed. BDL comes to mind; there are some others as well.
 
FloridaLarry said:
Without wishing to besmirch the memories of the two dead aviators, I do not understand their postumous promotions. The reports seem to make clear that the flight should have been survivable and that they did nothing heroic to save others in the vicinity of the crash. I grant that virtually no one would choose this method of gaining rank, but the lesson would seem to be reward for messing up.

Slightly analogous to the WW II habit of naming airports after local pilots-in-training who crashed. BDL comes to mind; there are some others as well.
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NOTHING in the report indicated this so I'm not sure where you found this "lesson".

As far as we all know, they may have already met every requirement for promotion, had already been selected for the next higher rank, and were on the way to the pinning ceremony. I think I'll give them the benefit. This was a good move by the Marine Corps (IMO); it provides a bit more for the families involved.
 
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MikeD said:
Yup. That's why it's a Land Immediately. Normally a power-on landing, as autorotation isn't required, and often making minimal changes in power so as to not cause further stress to a transmission that is out of oil and could seize at any time. But the big deal is, get on the ground yesterday. Because when that transmission seizes, so do your rotors.
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I've seen a few subtly different phrases in airline manuals on the subject of Put It Down Right Away. While I'm not a Captain, I do think about these things from the right seat should the need arise. According to My Airline, Inc.'s philosophy, it's up to me to fly while the Captain manages, so I try to think these things through ahead of time, when I do think about them.
  • Land at the nearest suitable airport. This rather unambiguous instruction means that an emergency is declared (whether or not assistance is required) and you land right away at the nearest strip of concrete. Some of our "red" messages or emergency non-annunciated procedures include this directive, along with a handful of cautions (yes) that will eventually damage the aircraft or our ability to operate it. Oh, and powerplant failures. Because 14 CFR 121.565.
  • Land as soon as practical. This is a more flexible directive that allows for the consideration of passenger handling, the availability of maintenance facilities, and so on, but it still indicates a need to land without undue delay. Flight continuation may make it a Land at the Nearest Suitable Airport.
  • Land immediately at the nearest suitable airport. Do not delay an approach and landing to accomplish the following procedures. This sentence (or something very similar) appeared in AOM1 at American Eagle in our electrical smoke-fire procedures. I took it to mean that any strip of concrete or asphalt long enough for the EMB-145 was to be considered, with all other considerations suspended, including the completion of messing about with buttons and breakers. The idea in that case was to give you some way to try to control the fire while still pointing at somewhere to get out of a burning airplane.
  • WARNING: Consider an immediate landing. This is in the EMB 175 QRH for certain kinds of smoke-fire. This is Embraer's equivalent of "put it down under control, on or off pavement, but put it down right now" I think, for the E-Jet.
Just my thoughts.
 
Autothrust Blue said:
I've seen a few subtly different phrases in airline manuals on the subject of Put It Down Right Away. While I'm not a Captain, I do think about these things from the right seat should the need arise. According to My Airline, Inc.'s philosophy, it's up to me to fly while the Captain manages, so I try to think these things through ahead of time, when I do think about them.
  • Land at the nearest suitable airport. This rather unambiguous instruction means that an emergency is declared (whether or not assistance is required) and you land right away at the nearest strip of concrete. Some of our "red" messages or emergency non-annunciated procedures include this directive, along with a handful of cautions (yes) that will eventually damage the aircraft or our ability to operate it. Oh, and powerplant failures. Because 14 CFR 121.565.
  • Land as soon as practical. This is a more flexible directive that allows for the consideration of passenger handling, the availability of maintenance facilities, and so on, but it still indicates a need to land without undue delay. Flight continuation may make it a Land at the Nearest Suitable Airport.
  • Land immediately at the nearest suitable airport. Do not delay an approach and landing to accomplish the following procedures. This sentence (or something very similar) appeared in AOM1 at American Eagle in our electrical smoke-fire procedures. I took it to mean that any strip of concrete or asphalt long enough for the EMB-145 was to be considered, with all other considerations suspended, including the completion of messing about with buttons and breakers. The idea in that case was to give you some way to try to control the fire while still pointing at somewhere to get out of a burning airplane.
  • WARNING: Consider an immediate landing. This is in the EMB 175 QRH for certain kinds of smoke-fire. This is Embraer's equivalent of "put it down under control, on or off pavement, but put it down right now" I think, for the E-Jet.
Just my thoughts.
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Those are the same concept as what I examined above, just worded differently; but equally important to know and consider as you say. Fully agree with them. The toughest one for a fixed wing guy is the "Land Immediately, (anywhere)", as it goes against the normal grain of an airfield. But there may be a time where it's the case, whether by choice or not.
 
dustoff17 said:
NOTHING in the report indicated this so I'm not sure where you found this "lesson".

As far as we all know, they may have already met every requirement for promotion, had already been selected for the next higher rank, and were on the way to the pinning ceremony. I think I'll give them the benefit. This was a good move by the Marine Corps (IMO); it provides a bit more for the families involved.
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You're right, Dustoff, we don't know.

The only facts available to us were those in the summary report, which attributed the crash first to pilot error, with other contributory factors (as usual). Then they get postumously promoted. This felt, to me, like a bad lesson, so I said so. I assume you have more experience in military rotary operations - I have none. If this was a kinder, gentler Marine Corps, it's not something this tax payer has seen much of. You are welcome to your opinion; I stated my concern.
 
MikeD said:
Those are the same concept as what I examined above, just worded differently; but equally important to know and consider as you say. Fully agree with them. The toughest one for a fixed wing guy is the "Land Immediately, (anywhere)", as it goes against the normal grain of an airfield. But there may be a time where it's the case, whether by choice or not.
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I always kept off-airport landings in the back of my mind in the Brasilia, where a pipe zone fire could result in having a wing come off.

Actually, that's probably the worst possible situation to have in that airplane. And with the one we did have at My Employer back in the "day," we're damn lucky.
 
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