Plane Down in Hudson River - NYC
Join Date: May 2002
Location: MA
Posts: 300
Likes: 0
Received 0 Likes
on
0 Posts
The Air Florida 737 that crashed in the Potomac would have lived if either pilot pushed the throttles forward regardless of what their gauges were telling them.
And it is hard to disagree with those who argue for the concept of the override button...
And it is hard to disagree with those who argue for the concept of the override button...
And it is hard to disagree with those who argue for the concept of the override button...
OTOH you can always opt for a "reserve thrust" option on an engine, which means it is certified for birds at that condition and then takeoff normally with less than reserve thrust and after ingesting birds you can have a big red button to push.
Or if it's EGT/TIT overlimits that really is part of your concern you can mandate the maximum allowable deterioration of an engine on-wing such that even after a bird ingestion you have lots of margin.
sorry there is no quick practical solution just multiple contributors to pick at.
Join Date: Jul 2004
Location: Found in Toronto
Posts: 615
Likes: 0
Received 0 Likes
on
0 Posts
There are two switches labeled "EEC". (Electronic Engine Control)
If you turn off EEC you will get all the power you want and will over temp the engines if you firewall the power levers.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
But what vintage Boeing are you addressing? The 733/734/735 have CFM56-3 with essentially hydromechanical controls w/electronic trim, where the 736/737/738/739 are FADEC machines. A great deal of difference. (Hint: look up FADEC!) 
Boeing aircraft already have "Override" switches.
There are two switches labeled "EEC". (Electronic Engine Control)
If you turn off EEC you will get all the power you want and will over temp the engines if you firewall the power levers.
There are two switches labeled "EEC". (Electronic Engine Control)
If you turn off EEC you will get all the power you want and will over temp the engines if you firewall the power levers.
So I'll have to be careful of the my use of the word overide if all it does is turn off a system. However any system left running I believe has has to meet its design intent without exceedances (caused by the system).
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
Yes, all Boeing FADEC aircraft have EEC switches. I believe this includes most 757, 767, 777, and the newer 737's.
Join Date: Feb 2008
Location: somewhere
Posts: 93
Likes: 0
Received 0 Likes
on
0 Posts
LOST IN SAIGON said :
As far I know on T7, you can only switch EEC to Alternate modes ( soft and hard )
In both cases , you keep overspeed protection ( N1 ) but you loose overboost protection ( overthrust ) . Can help anyway !
Boeing aircraft already have "Override" switches.
There are two switches labeled "EEC". (Electronic Engine Control)
If you turn off EEC you will get all the power you want and will over temp the engines if you firewall the power levers.
There are two switches labeled "EEC". (Electronic Engine Control)
If you turn off EEC you will get all the power you want and will over temp the engines if you firewall the power levers.
As far I know on T7, you can only switch EEC to Alternate modes ( soft and hard )
In both cases , you keep overspeed protection ( N1 ) but you loose overboost protection ( overthrust ) . Can help anyway !
Join Date: Jul 2007
Location: West Sussex
Age: 82
Posts: 58
Likes: 0
Received 0 Likes
on
0 Posts
The results of a serious bird event are usually much more complex than a reduction in efficiency causing EGT limitation.
Compressor damage will lead to a reduction (or elimination) of surge margin. The ability to select increased fuel flow would not help in this instance.
Much time is spent during engine certification in deciding the best course of action following bird ingestion, involving bleed management, throttle manipulation and so on.
In this case it seems that the ingestion event was so severe that the engines were overwhelmed. Overfueling would have served no purpose.
Aircraft are currently certificated against the most severe possible environmental hazards in terms of climate, icing etc.. Large flocking birds have only recently been recognised as a paticularly severe environmental hazard. The pioneering CAA paper was published in 2002, but I'm not sure if matters have progressed in the meantime.
Compressor damage will lead to a reduction (or elimination) of surge margin. The ability to select increased fuel flow would not help in this instance.
Much time is spent during engine certification in deciding the best course of action following bird ingestion, involving bleed management, throttle manipulation and so on.
In this case it seems that the ingestion event was so severe that the engines were overwhelmed. Overfueling would have served no purpose.
Aircraft are currently certificated against the most severe possible environmental hazards in terms of climate, icing etc.. Large flocking birds have only recently been recognised as a paticularly severe environmental hazard. The pioneering CAA paper was published in 2002, but I'm not sure if matters have progressed in the meantime.
Join Date: Sep 2005
Location: No one's home...
Posts: 416
Likes: 0
Received 0 Likes
on
0 Posts
VNAV path
Overboost on a jet engine. Over-temp, yes. Over-speed, yes. Overboost, no. Overboost is a recip term and problem.
In both cases , you keep overspeed protection ( N1 ) but you loose overboost protection ( overthrust ) . Can help anyway !
Join Date: Jun 2008
Location: London
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
I recall seeing a film that GE and IAE made, independently of each other, which showed a shower of dead chickens being shot into the engines. These tests were quite impressive but as with ALL tests they are never conclusive. The reason?
You cannot allow for every possible situation.
This was one and you can draw the circles round it as tight as you want but it is unique.
So is some of the garbage written in the aftermath of this single incident.
You cannot allow for every possible situation.
This was one and you can draw the circles round it as tight as you want but it is unique.
So is some of the garbage written in the aftermath of this single incident.
Join Date: Dec 2000
Location: Canada
Posts: 141
Likes: 0
Received 0 Likes
on
0 Posts
It is critical to remember that the CFM56 was certified under the OLD FAR 33 standards that are based on a single 4 lb bird. The new Standard is a single 8 lb bird. Many migratory birds, especially Canada Geese exceed even 8 lbs.
Lastly it is important to understand what the standard for ceritfication of the engine for a single large bird is:
(3) Ingestion of a single large bird tested under the conditions prescribed in this section may not cause the engine to:
(i.) Catch fire;
(ii.) Release hazardous fragments through the engine casing;
(iii.) Generate loads greater than those ultimate loads specified under Sec. 33.23(a); or
(iv.) Lose the ability to be shut down.
It doesn't have to continue to run.....
Once all the FDR data is available for this event, the results of the engine teardown and the bird data is know it will be interesting to see how the information is presented.
Information to date indicates that if the aircraft did hit a flock of geese that the engines exceeded the certification standard.
Lastly it is important to understand what the standard for ceritfication of the engine for a single large bird is:
(3) Ingestion of a single large bird tested under the conditions prescribed in this section may not cause the engine to:
(i.) Catch fire;
(ii.) Release hazardous fragments through the engine casing;
(iii.) Generate loads greater than those ultimate loads specified under Sec. 33.23(a); or
(iv.) Lose the ability to be shut down.
It doesn't have to continue to run.....
Once all the FDR data is available for this event, the results of the engine teardown and the bird data is know it will be interesting to see how the information is presented.
Information to date indicates that if the aircraft did hit a flock of geese that the engines exceeded the certification standard.
Interesting that both engines had locally damaged Inlet Guide vanes. (not commonly seen)
Is there any controll logic that having sensed this could fail-safe all the engine IGVs to full open?
I still feel that it is significant that the engines appeared to be in a fail safe mode not requiring pilot intervention to protect them furthur
Is there any controll logic that having sensed this could fail-safe all the engine IGVs to full open?
I still feel that it is significant that the engines appeared to be in a fail safe mode not requiring pilot intervention to protect them furthur
Join Date: Aug 2006
Location: firmly on dry land
Age: 81
Posts: 1,541
Likes: 0
Received 0 Likes
on
0 Posts
Regarding the bird ingestion test, does the test make any distinction between fans of different diameters?
One might assume that a larger fan has more robust blades and guide vanes than a smaller one therefore they can offer the same degree of resistance or survivability.
On the other hand a larger fan may be more susceptible to damage, for the same bird, if it is struck on the outer edge of the fan disc.
Also the larger intake will have a higher probabilty of catching a bird than a smaller one.
So, is it a one size fits all or do they factor in fan size?
One might assume that a larger fan has more robust blades and guide vanes than a smaller one therefore they can offer the same degree of resistance or survivability.
On the other hand a larger fan may be more susceptible to damage, for the same bird, if it is struck on the outer edge of the fan disc.
Also the larger intake will have a higher probabilty of catching a bird than a smaller one.
So, is it a one size fits all or do they factor in fan size?
Join Date: Jul 1999
Location: 58-33N. 00-18W. Peterborough UK
Posts: 3,040
Likes: 0
Received 0 Likes
on
0 Posts
Avweb.
According to the NTSB, the engine showed "evidence of soft body impact damage," but failed to supply visual evidence of "organic material" (read: birds) following its unscheduled powerwashing in the Hudson River on Jan. 15. The left engine, previously attached to the US Airways Airbus A320, was dented on both the spinner and intake lip. Plus, five booster inlet vanes were damaged and eight outlet guide vanes were missing. Both engines will now be shipped to Cincinnati where investigators will oversee a complete teardown and use "advanced technology" to detect the existence of the aforementioned organic material.
According to the NTSB, the engine showed "evidence of soft body impact damage," but failed to supply visual evidence of "organic material" (read: birds) following its unscheduled powerwashing in the Hudson River on Jan. 15. The left engine, previously attached to the US Airways Airbus A320, was dented on both the spinner and intake lip. Plus, five booster inlet vanes were damaged and eight outlet guide vanes were missing. Both engines will now be shipped to Cincinnati where investigators will oversee a complete teardown and use "advanced technology" to detect the existence of the aforementioned organic material.
Join Date: Sep 2008
Location: MI
Posts: 570
Likes: 0
Received 0 Likes
on
0 Posts
It is simply not possible to protect or certify one of these turbine engines (no matter the size or make) against all hazards they might encounter. It is a 'risk' that must be taken if one chooses to fly.
Last edited by DC-ATE; 26th Jan 2009 at 19:54.
Regarding the bird ingestion test, does the test make any distinction between fans of different diameters?
So, is it a one size fits all or do they factor in fan size?
So, is it a one size fits all or do they factor in fan size?
The later generation engines (not the CFM56) increases the size of the birds vs capture area and yes as size goes up the quantity goes down just the same as mother nature per square foot.
Join Date: Feb 2002
Location: The Sandpit
Posts: 555
Likes: 0
Received 0 Likes
on
0 Posts
Both engines were hit by at least 1 and possibly several LARGE birds. Damage was such that several IGV's and OGV's were euther damaged or even missing. And yet the would be "engineers" here on PPRUNE seem to think that a big red switch to allow the pilot to over-ride the FADEC would have saved the day (or at least allowed at dry landing)
Well listen up! The engines were knackered, shot. Damaged/missing IGV's/OGV's would have disturbed the airflow through the engine so much that any pilot over-ride would have had, if anything, the opposite effect and caused a massive surge.
The vast majority of a/c flying around today are FADEC controlled. FADEC does not limit EGT (it's quite possible to overtemp a FADEC engine as the frequent overtemp inspections that are carried out by engineers all over world are testimony to. FADEC will HELP prevent over-boost and overspeed of engines but by all accounts this was not the issue it was not producing enough power not limited 'cos it was producing too much.
Hats off to the pilots who did an excellent job of getting the a/c down without loss of life and WAIT for the report to establish the full story.
Well listen up! The engines were knackered, shot. Damaged/missing IGV's/OGV's would have disturbed the airflow through the engine so much that any pilot over-ride would have had, if anything, the opposite effect and caused a massive surge.
The vast majority of a/c flying around today are FADEC controlled. FADEC does not limit EGT (it's quite possible to overtemp a FADEC engine as the frequent overtemp inspections that are carried out by engineers all over world are testimony to. FADEC will HELP prevent over-boost and overspeed of engines but by all accounts this was not the issue it was not producing enough power not limited 'cos it was producing too much.
Hats off to the pilots who did an excellent job of getting the a/c down without loss of life and WAIT for the report to establish the full story.