Jet Blue A320 loses two hydraulic systems
Join Date: Aug 2005
Location: fl
Posts: 2,525
Likes: 0
Received 0 Likes
on
0 Posts
My major airline in the US advised not dumping fuel if the landing was just as safe landing over weight. I wondered how this would sound at the hearing so decided overweight landing couldn't be as safe as landing at Max landing weight so ignored their advice knowing it was put out by the management people. A few months later I got a 727 with a radar problem written off as re racked ok for service. I told the FO we have a bad radar and we need it for this flight through a tropical storm to south America so expect it to quit since they didn't fix it.
We hit a bump on the runway at rotation and the radar quit but we knew where the close in weather was so requested a straight out departure. Circuit breakers , pounding on scope and normal pilot techniques didn't work so we went off shore and dumped fuel to max landing weight and came back to MIA. Never heard a word about why didn't we land over max landing weight and no hearing. I think the hearing is when you follow their advice and land overweight and have to explain why.
We hit a bump on the runway at rotation and the radar quit but we knew where the close in weather was so requested a straight out departure. Circuit breakers , pounding on scope and normal pilot techniques didn't work so we went off shore and dumped fuel to max landing weight and came back to MIA. Never heard a word about why didn't we land over max landing weight and no hearing. I think the hearing is when you follow their advice and land overweight and have to explain why.
Join Date: May 2005
Location: On a good day - at sea
Posts: 263
Likes: 0
Received 0 Likes
on
0 Posts
GIA
I think that PTU switch needs an AD on it to increase the inspection interval. The current Maint progrogram schedule requires a check every 4 yrs but if it's faulty this one switch will cause a dual HYD failure..
Consider that the the PTU is always electrically supplied and the Y+G HYD delta P normally controls the on/off function. If that PTU OFF switch is faulty there is nothing to interrupt power to the PTU in the event of delta P drop. So with a faulty a switch and a leak on one side, a dual hydraulic failure is inevitable.
eg
The first step in HYD LO LVL/PRESS ECAM though is PTU.....OFF.
The switch is faulty though so the PTU continues to run.
The PTU overheats (rather quickly by the way), the seals disintegrate, and the second system drains away.
Now you've lost G and Y
There has been a recent case of an A319 crew not being able to switch the PTU off due to a faulty PTU switch... Therefore a single hydraulics low level activated the PTU which has overheated and taken out the second hydraulic system...
Consider that the the PTU is always electrically supplied and the Y+G HYD delta P normally controls the on/off function. If that PTU OFF switch is faulty there is nothing to interrupt power to the PTU in the event of delta P drop. So with a faulty a switch and a leak on one side, a dual hydraulic failure is inevitable.
eg
The first step in HYD LO LVL/PRESS ECAM though is PTU.....OFF.
The switch is faulty though so the PTU continues to run.
The PTU overheats (rather quickly by the way), the seals disintegrate, and the second system drains away.
Now you've lost G and Y
Join Date: Mar 2006
Location: Choroni, sometimes
Posts: 1,974
Likes: 0
Received 0 Likes
on
0 Posts
I think the hearing is when you follow their advice and land overweight and have to explain why.
Write it down in the techlog and that is it.
Join Date: Nov 2009
Location: USA
Posts: 74
Likes: 0
Received 0 Likes
on
0 Posts
I've been saying the following prior to every takeoff above MLW for the last 20 years:
"If we have to come right back, we'll be overweight for landing. We will consider the reason for the return and the condition of the aircraft and decide whether to dump (burn, depending on the aircraft) fuel or come right back and land overweight."
I have landed overweight twice and have burned down to MLW once, because, in my professional judgement those were the best courses of action based on the circumstances.
Nobody who was not physically in the cockpit of that airplane has the information, much less the standing, to critique their decision making.
"If we have to come right back, we'll be overweight for landing. We will consider the reason for the return and the condition of the aircraft and decide whether to dump (burn, depending on the aircraft) fuel or come right back and land overweight."
I have landed overweight twice and have burned down to MLW once, because, in my professional judgement those were the best courses of action based on the circumstances.
Nobody who was not physically in the cockpit of that airplane has the information, much less the standing, to critique their decision making.
Last edited by BobnSpike; 21st Jun 2012 at 20:54.
Join Date: Feb 2000
Posts: 151
Likes: 0
Received 0 Likes
on
0 Posts
Pitotheat. I appreciate your comments but cannot believe that any fbw Airbus pilot thinks the manual reversion resembles that on some Boeing aircraft. A sim generally gives a reasonable interpretation of flight characteristics but is questionable when approaching the edges of the flight envelope in a heavily degraded mode.
According to the A320 HYD G+B Summary, the Actual Landing Distance at Sea Level for 74 tons is 3000 mts plus 3% per 1000 ft airport elevation.
I have never flown from LAS, but as far as I can see there is a landing runway with more than 4000 mts available.
So I don't see the reason for being flying for almost 4 hours after having a double hydraulic failure....something else should be around...
Don't take me wrong I am not judging the crew, I would like to know why they were holding for such a long period of time.
I have never flown from LAS, but as far as I can see there is a landing runway with more than 4000 mts available.
So I don't see the reason for being flying for almost 4 hours after having a double hydraulic failure....something else should be around...
Don't take me wrong I am not judging the crew, I would like to know why they were holding for such a long period of time.
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
Bokkenrijder:
Your reaction is strange.
After the embargo and fuel prices went up, the company gave their "blessings" to overweight landings to save fuel so long as it was as safe as dumping. I tried to make that clear earlier.
Simulating an overweight landing would have been a waste of time. The simulator is "similar," not exact.
But, you have your views and my major airline and others did not share your views.
Again, two very strange statements;
1) With the 1973 embargo, I assume you are referring to the 1973 oil embargo? Why would any pilot let commercial considerations take priority during a severe technical failure? The whole point of overweight landings is to save time, not fuel!
2) Why would you treat a sim session any different than a real life scenario? Isn't the the whole purpose of sim training and checking to simulate real world scenarios?
But, you have your views and my major airline and others did not share your views.
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
bubbers44:
You are the first one, I believe, to make that definitive of a statement about what was available.
Given that, it seems like Edwards AFB would have been the place to go.
If yellow and green hydraulics were gone you have no reversers, no brakes other than the accumulators and no flaps. Think about it.
Given that, it seems like Edwards AFB would have been the place to go.
Thread Starter
Join Date: Dec 2008
Location: PDX
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
[Not a pilot] Would there be a reluctance to leave the vicinity of a three-mile-long runway in favor of a fifteen-mile-long runway around two hundred miles away (with presumably few suitable landing opportunities in between)?
re: why not practice overweight landings. Because it'll be the same as a "normal" landing, just with higher numbers. Do you really need to practice setting ref at 164 v. 134?
As 7 Stroke says, there are a bunch of other reasons to consider dumping. Some flight control malfunctions have a speed additive, the 727 zero flap landing is ref +60. At that point even a landing under max landing weight is going to push tire speeds.
As 7 Stroke says, there are a bunch of other reasons to consider dumping. Some flight control malfunctions have a speed additive, the 727 zero flap landing is ref +60. At that point even a landing under max landing weight is going to push tire speeds.
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
Typically do engine out landings right below max takeoff weight. Gives you an indication of the plane's performance.
Fly the UAL DC-10 to the desert? They were barely able to control it so flying it for an hour or two to reach the desert would have increased the risk of losing control enroute.
Fly the UAL DC-10 to the desert? They were barely able to control it so flying it for an hour or two to reach the desert would have increased the risk of losing control enroute.
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
[Not a pilot] Would there be a reluctance to leave the vicinity of a three-mile-long runway in favor of a fifteen-mile-long runway around two hundred miles away (with presumably few suitable landing opportunities in between)?
What do you do if enroute to the airport two hundred miles away you start having problems with the third hydraulic system?
Odds of that happening? Pretty small but what are the odds of losing two hydraulic systems?
Join Date: Nov 2003
Location: Over the Moon
Posts: 780
Likes: 0
Received 0 Likes
on
0 Posts
The 320 FCTM states very clearly that a dual hydraulic failure is a MAYDAY and that you should land ASAP (in red)
Holding next to a suitable runway for the purpose of reducing weight, with this failure, is a mugs game, end of.
If you have a pressure differential between the green and yellow system of 500psi the PTU will run. If this is due to fluid loss then the good system will overheat running the PTU and so will also go down. That's why the 1st action on ECAM for green or yellow overheats, loss of fluid etc is to switch the PTU off thus preventing the loss of the 2nd system.
Snag is one of the main times you will lose the green system fluid is on gear retraction after t/o. Depending on your mod state you may not know this until your above 1500' aal due to take off inhibit restricting the warnings that come up. At that stage it may well be too late to prevent the 2nd system from failing due to an overheat. However you will get it back once it has cooled and once you've switched the PTU off it will work fine so your back to 2 systems. This may well be what occurred in this instance and if so holding to burn fuel would be fine as you only have a single failure. In fact depending on the destination continueing may be fine too.
Airbus have a mod out to prevent the after take off gotcha but I guess not all will have it?
Holding next to a suitable runway for the purpose of reducing weight, with this failure, is a mugs game, end of.
If you have a pressure differential between the green and yellow system of 500psi the PTU will run. If this is due to fluid loss then the good system will overheat running the PTU and so will also go down. That's why the 1st action on ECAM for green or yellow overheats, loss of fluid etc is to switch the PTU off thus preventing the loss of the 2nd system.
Snag is one of the main times you will lose the green system fluid is on gear retraction after t/o. Depending on your mod state you may not know this until your above 1500' aal due to take off inhibit restricting the warnings that come up. At that stage it may well be too late to prevent the 2nd system from failing due to an overheat. However you will get it back once it has cooled and once you've switched the PTU off it will work fine so your back to 2 systems. This may well be what occurred in this instance and if so holding to burn fuel would be fine as you only have a single failure. In fact depending on the destination continueing may be fine too.
Airbus have a mod out to prevent the after take off gotcha but I guess not all will have it?
Last edited by Ashling; 22nd Jun 2012 at 01:46.
Join Date: Jan 2008
Location: Atlanta, GA, USA
Posts: 349
Likes: 0
Received 0 Likes
on
0 Posts
Wow fascinating thread.
My ignorant first reaction would have been - two systems go out, and I'm thinking someone on the ground fracked up and the third is at risk, so get down ASAP, and I would have.
My ignorant first reaction would have been - two systems go out, and I'm thinking someone on the ground fracked up and the third is at risk, so get down ASAP, and I would have.
Join Date: Aug 2010
Location: Worldwide
Posts: 1,468
Likes: 0
Received 0 Likes
on
0 Posts
Reading the report it looks like initially they had 2 hydraulic systems faillure, but they were then able to recover one of them.
So at that point they were flying with 2 hydraulic systems, yellow and blue, so probably a good decision to hold and burn off excess fuel.
So at that point they were flying with 2 hydraulic systems, yellow and blue, so probably a good decision to hold and burn off excess fuel.
Join Date: Oct 2007
Location: fort sheridan, il
Posts: 1,656
Likes: 0
Received 0 Likes
on
0 Posts
if they had yellow back, couldn't they use the ptu to power nosewheel steering through the green? assuming theyhad hydraulic fluid and just no pump on the green?
news reports said no nosewheel steering after landing.
if this plane is designed to have a failure mode that eventually causes, ''lurching'' about in flight...someone didn't think this thing through very well.
I know how important it is to get the gear UP after takeoff...in the event of an engine out and performance needs. However, losing a hydraulic system, using the PTU to get the gear up, then burning out the PTU because you forget to turn off the switch, causing an overheat in the OTHER hyd system doesn't make much sense to me.
so now the gear needs emergency extension (with no way to retract on a single engine go around) and you've lost too much.
in this case, both engines kept running, and leaving the gear down might have prevented overheating the other system.
could the "LURCHING" be lowering the main gear related????????
in the final analysis, being on the ground, wishing you were in the air is better than being in the air wishing you were on the ground.
news reports said no nosewheel steering after landing.
if this plane is designed to have a failure mode that eventually causes, ''lurching'' about in flight...someone didn't think this thing through very well.
I know how important it is to get the gear UP after takeoff...in the event of an engine out and performance needs. However, losing a hydraulic system, using the PTU to get the gear up, then burning out the PTU because you forget to turn off the switch, causing an overheat in the OTHER hyd system doesn't make much sense to me.
so now the gear needs emergency extension (with no way to retract on a single engine go around) and you've lost too much.
in this case, both engines kept running, and leaving the gear down might have prevented overheating the other system.
could the "LURCHING" be lowering the main gear related????????
in the final analysis, being on the ground, wishing you were in the air is better than being in the air wishing you were on the ground.