Cessnaflyer
Wooooooooooooooooooooooooooooooo
Baby dash was pretty good. The PW121 is similar to the King Air 200 and the PT6. The ATR was a bit more difficult.
King Air crashed into FSI Witchita
- Thread starter tlewis95
- Start date
deadstick
Well-Known Member
On the 200, the feathering is done manually with the prop lever or automatically by dumping the oil at the oversped governor. In the event that the prop control is FUBAR'd, you might be able to affect a feathering by depressing the AFX TEST switch to the TEST position.
AFX is a required to be operational for aircraft with 4 bladed Hertzel props. That's a boat-load of drag. The 3-bladed Hertzels and all McCrappy props are ok without it. For aircraft that we not delivered with AFX, Raisbeck has this voodoo cam system called MagiCam that essentially does the same thing by (IIRC) resetting the stops as power is applied. There is no switch to arm or test.
I was flying a MagiCam E90 and went to the sim (C90B) with AFX. Of course I forgot to arm the AFX because I didn't have to in my plane. Sure enough, I had an engine failure on takeoff. I didn't crash, but that sucker was a handful until I manually feathered the prop.
If this was an FCU failure that resulted in a roll back, I'm not sure the AFX would engage. It just depends on what the torque went down to.
Autothrust Blue
Welcome aboard the Washington State Ferries
-dusts off Brasilia knowledge- I think I remember enough about this, but take it with a grain of salt.
The SFIS is intended to prevent idiots from doing "I wonder what this does" in-flight with the power levers; beyond that, I can't think of any real safeguard that was added to the system as an afterthought that would have really prevented either the ASA 2311 or ASA 529 accidents. The accidents were failures of engineering, maintenance, and quality control. No two pilots in the world would have been able to handle the ASA 2311 scenario (at those airspeeds the aircraft would not have been controllable following the inflight reversal of the propeller); and I find it amazing that anyone survived ASA 529 following the major structural damage that the aircraft sustained during the initial event, much less the off-airport landing and postimpact fire.
The fact remains that if the blade angle is reduced below the normal inflight range inflight, dependent upon engine speed and airspeed, you might not be able to get the propeller back into a flight range, much less feathered. (You must reduce Np below roughly 125% for even the electrical pump to have sufficient oomph to drive feathering if memory serves.) Overspeed governing won't do you any good if it really runs away on you, and it also won't do you any good if the transfer tube disconnects from the PCU.
If memory serves, the aircraft has an exemption from the FAA anyway regarding surviving an inflight loss of a propeller blade too.
The ASA 2311 guys didn't have a chance. That prop was mechanically disconnected from anything that they could have used to control it.
Erm, they're not all that much of a safeguard, and they're not all that extraordinary either - that propeller (as I'm sure you know) is fail-deadly and there's still only one way to feather the propeller (yes, I know that you can do it with the condition lever, the automatic feathering system, the electric feather switch, or by pulling the fire handle, but three of those use the same pump, and all of them use the same mechanical bits and oil to move the blades to feather).
The SFIS is intended to prevent idiots from doing "I wonder what this does" in-flight with the power levers; beyond that, I can't think of any real safeguard that was added to the system as an afterthought that would have really prevented either the ASA 2311 or ASA 529 accidents. The accidents were failures of engineering, maintenance, and quality control. No two pilots in the world would have been able to handle the ASA 2311 scenario (at those airspeeds the aircraft would not have been controllable following the inflight reversal of the propeller); and I find it amazing that anyone survived ASA 529 following the major structural damage that the aircraft sustained during the initial event, much less the off-airport landing and postimpact fire.
The fact remains that if the blade angle is reduced below the normal inflight range inflight, dependent upon engine speed and airspeed, you might not be able to get the propeller back into a flight range, much less feathered. (You must reduce Np below roughly 125% for even the electrical pump to have sufficient oomph to drive feathering if memory serves.) Overspeed governing won't do you any good if it really runs away on you, and it also won't do you any good if the transfer tube disconnects from the PCU.
If memory serves, the aircraft has an exemption from the FAA anyway regarding surviving an inflight loss of a propeller blade too.
Do not shut down an engine on the Brasilia with the propeller unfeathered unless a greater emergency exists. Your best bet - barring a total loss of oil (AFFECTED ENGINE - DO NOT SHUT DOWN; POWER LEVER - FLT IDLE) or the disconnection of the PCU from the transfer tube (utterly impossible situation for you to do anything about at all other than close the power lever, frantically try to feather it, and try to steer), is to keep the power plant (and the oil pumps, consequently) running and keep trying to feather it.
The ASA 2311 guys didn't have a chance. That prop was mechanically disconnected from anything that they could have used to control it.
gotWXdagain
Polished Member
It actually is the Overspeed governor on the Pilatipi as well, however that's the only way to feather. In fact the book says specifically that feathering will not occur unless the battery bus is powered.
ahw01
Well-Known Member
So if your rudder input still has the nose drifting why not pull the good engine, land on the last 500 ft and go through the fence. Split second stuff I guess.
Also the logbook excerpt had the capt logging some interesting things. Sim time was logged as AMEL. Also I think he had PPL ASEL privileges but flew a C-206 a few weeks prior.
No big deal obviously but just interesting.
Also the logbook excerpt had the capt logging some interesting things. Sim time was logged as AMEL. Also I think he had PPL ASEL privileges but flew a C-206 a few weeks prior.
No big deal obviously but just interesting.
Tommay85
Well-Known Member
Oh no, I wasn't commenting on the crash at all, just the reason the 120 prop is the way it is. The reason the book gave at least.
I know there's guys with Dash 8 and Saab time on here. Curious if their prop control systems were the same (requiring oil pressure to move the prop). Or even VERY big props like a C130 or P3. Or even old VERY big props found on the front of radials back in the day.
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Autothrust Blue
Welcome aboard the Washington State Ferries
I can speak to those old props, at least.
Although I am in a hurry, so I'll let John Deakin speak to the Martin 404's full-feathering, constant-speed, reversible propeller.
Autothrust Blue
Welcome aboard the Washington State Ferries
Tommay85
Well-Known Member
Indeed, and training would be the one argument I would have. Even in the 99 (similar to a KingAir), we didn't talk about or train putting it back on the ground. No V1, but if you were in the air, you should be fine to stay in the air. If you're still on the ground, you should be fine aborting. That was about it really from what I remember.
I would definitely be going into the air after V1 in the Metro, even on an 11,000 foot runway. For one, with the gear down, any power reduction would be an instant crash if you some how got it out of ground effect in that condition. The gear needs to be up to just to get out of ground effect. Putting it the gear back down and reducing power to prevent a VMC roll; you're already far too slow for that to work. In the 120 and the Metro, I'm not trained and haven't practiced putting it back down on the runway. Maybe I'd be on my A-game and it'd work out. But any pilot can definitely pull off a post V1 cut (or any trained emergency) with a head cold and no sleep, and most likely be successful.
Tommay85
Well-Known Member
Looks like oil pressure differentials are what move this prop as well. I don't see any springs, weights, or gas charges. I'm studying for Metro recurrent, no way I'm going to try to figure this thing out right now. Schematics make my grey matter boil anyways!
z987k
Well-Known Member
Or if you lost oil pressure, it'd eventually make it's way to feather anyways. That's the fail safe.
deadstick
Well-Known Member
"Eventually" with the KA, too. It takes awhile on shutdown unless you move the prop levers.
I shut down one that had the Raisbeck Quiet Fan prop. Even with the prop feathered, the prop continued to rotate due to the twist in the blades. Come to think about it, it might have been rotating backwards. On the 3-bladed props, with AFX, when you shut one down in flight with the condition lever, it feathers and stops pretty darn quickly.
Tommay85
Well-Known Member
The Dash 8 has springs and/or counterweights and/or gas charges to move the prop to feather with a complete loss of oil pressure?
I'm genuinely curious. Embraer seems pretty sure that the props that it has fitted to it's 100 series PWs is far beyond the capability of more traditional prop governing systems found with smaller propellers. The last ditch effort with the 120 is the electric feathering pump that pulls oil from a separate tank. Is that not the case with the Dash 8?
Tommay85
Well-Known Member
My only experience with NTS is with the Merlin IV (Metro III with a flat floor and 16,000 MGTOW). I've done two in-flight shut downs. I agree, it doesn't do much. Supposedly the gear is the biggest killer at V1, but I suspect you'd be stuck pretty low until the NTS got the prop into the 30% range or less. Which would take at least 10 seconds or more from what I've seen.
z987k
Well-Known Member
From shutting down, allowing to NTS and then feathering a -10 on an AC90, the NTS works really fast(almost instantly) and once you have the condition leaver in feather, it's there in ~2 seconds.
Tommay85
Well-Known Member
It might work more quickly at V1. It seems to not be an issue in the sim at all if it is or is not working though, or isn't the main focus. The gear makes or breaks the V1 cut more than the prop in that plane.
From stop button pushed until pulling the stop/feather knob (pulled at 30% for a pre-planned), it was at least 10 seconds when shutting down in flight. At 160ish kias both times.
Cessnaflyer
Wooooooooooooooooooooooooooooooo
The Dash-8-100 has an auxiliary feather pump and a dumping solenoid from the low pitch side of the propeller. The propeller can be feathered three ways; by condition lever, auto-feather and alternate feather. The alternate feather basically goes through the same process the auto-feather does to dump oil and have the prop feather if the first two methods don't work. The props can also be brought back from feather using the alternate feather switch.
Tommay85
Well-Known Member
So you need oil pressure of some kind then, right? No oil pressure, aux pump fails, and/or linkage failure, the prop is stuck in whatever position this happens in, correct?
I have a feeling the props systems are identical or similar, with different names for the components. Short of a linkage failure, the 120 has the pitch stop gap that would turn it into a fixed pitch propeller basically. With complete loss of oil pressure to the propeller system and an otherwise functioning engine. The aux feather can over-ride this.
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Cessnaflyer
Wooooooooooooooooooooooooooooooo
Yep, sounds about the same. However losing all these systems is going to have a very low probability.
Autothrust Blue
Welcome aboard the Washington State Ferries
Ever wonder why dry motoring in all the prop-related procedures is 20 seconds?