Hole In Engine on NWA 757
03-27-2009, 10:25 AM
#1
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Hole In Engine on NWA 757
A former law student sent this to me. Interesting that the engine kept on running, or that the hole didn't get bigger. Wouldn't one of the dials and gauges be going off in the cockpit? And I thought that after 9/11 the cockpit door is locked during flight and nobody can come out even for a pee break? I'm no captain, but I suppose I'd want to see this myself.
First a thud, then a hole in jet engine
First a thud, then a hole in jet engine
03-27-2009, 10:43 AM
#2
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No, You Can Pee
Vagabond:
You can come out (can you imagine going 14 hours across the Pacific without a pee-break?). There are security measures that must be complied with before the cockpit door is opened. (Sniper...editted for security).
During icing conditions, before takeoff, one of the cockpit crew has to come back and visually view the wings when within 5 minutes of takeoff.
Looks like it threw a first-stage Fan blade. Would this show up on the gauges? Not necessarily. They'd say "What was that?", and some parameters might be a little--or a lot--out of whack.
You can come out (can you imagine going 14 hours across the Pacific without a pee-break?). There are security measures that must be complied with before the cockpit door is opened. (Sniper...editted for security).
During icing conditions, before takeoff, one of the cockpit crew has to come back and visually view the wings when within 5 minutes of takeoff.
Looks like it threw a first-stage Fan blade. Would this show up on the gauges? Not necessarily. They'd say "What was that?", and some parameters might be a little--or a lot--out of whack.
Last edited by UAL T38 Phlyer; 03-27-2009 at 11:14 AM.
03-27-2009, 10:46 AM
#3
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My theory would be that they had zero indication of anything in the cockpit. I am sure the passenger pointed it out to the FA who then called the flight deck and said "Ummm Yeah there is a HUGE Freakin hole in the engine." At that point I would figure that the captain would take a look himself.
And we can use the potty.
And we can use the potty.
03-27-2009, 10:49 AM
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Perfectly handled, IMO. Passenger notices something, passes concern on the FA, FA informs pilots, pilots make decision to take action.
As for one of the dials or gauges going off, that would depend on factors that aren't easily known from the article or the photo. The gauge may have been indicating something, but the pilot visually seeing it confirmed it.
Pilots may choose to come out of flightdeck during flight. A discussion on a public forum about why they might choose to do so, or the procedures involved in the decision isn't appropriate, IMO.
As for one of the dials or gauges going off, that would depend on factors that aren't easily known from the article or the photo. The gauge may have been indicating something, but the pilot visually seeing it confirmed it.
Pilots may choose to come out of flightdeck during flight. A discussion on a public forum about why they might choose to do so, or the procedures involved in the decision isn't appropriate, IMO.
03-27-2009, 11:21 AM
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If it did not throw a blade, you may not know anything. If you did chuck a blade, you would probably feel the vibration.
This looks like it could be a few things. Everything from a blade exit point, to a discharge point for some lightning.
This looks like it could be a few things. Everything from a blade exit point, to a discharge point for some lightning.
03-27-2009, 11:40 AM
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03-27-2009, 11:55 AM
#7
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Wouldn't throwing a blade catastrophically disrupt the balance of the fan, causing the engine within the cowling to just throw itself apart?
Looks like a pretty violent event in this video.
Fan blade separation test:
YouTube - Blade Containment
If the video is anything like what would be typical, there doesn't seem to be enough damage to the cowling of the NW jet in the photo for a fan blade separation.
Just a guess.
Looks like a pretty violent event in this video.
Fan blade separation test:
YouTube - Blade Containment
If the video is anything like what would be typical, there doesn't seem to be enough damage to the cowling of the NW jet in the photo for a fan blade separation.
Just a guess.
03-27-2009, 12:31 PM
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Blade Containment
AZ:
Those tests are usually done at full-rated power. That would mean maximum rpm, as well as the pressure behind it.
Sounds like this happened at cruise, where power is significantly reduced, say, on the order of 90% rpm. Every 10% reduction in rpm reduces the forces on the blade by about 50%.
So it wouldn't be as violent as the video. Also, if only a portion of a blade came loose...not as bad, either.
Those tests are usually done at full-rated power. That would mean maximum rpm, as well as the pressure behind it.
Sounds like this happened at cruise, where power is significantly reduced, say, on the order of 90% rpm. Every 10% reduction in rpm reduces the forces on the blade by about 50%.
So it wouldn't be as violent as the video. Also, if only a portion of a blade came loose...not as bad, either.
03-27-2009, 01:22 PM
#9
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Wouldn't the containment ring normally keep the piece from exiting the cowling? Looks like the piece came out (if that is what caused the hole) at about the 8 o'clock position if viewed from head on. Good thing it wasn't the 10 o'clock.
Didn't something like that happen down in Pensacola a few years back? As I recall a piece penetrated the fuselage injuring/killing a passenger.
Didn't something like that happen down in Pensacola a few years back? As I recall a piece penetrated the fuselage injuring/killing a passenger.
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