Ask The Pilot

[mjt57]

gine. Once the shaft failed, it was no longer able to transfer the enormous amount of power that it was catching to the compressor, to it simply accelerated...until it failed due to massive overspeed. That would have taken perhaps a couple of seconds.

Do you know what speed that the turbine reached?

If they could be quick enough, the event would stop at the shaft failure stage...so it would remain a 'simpler' event.

I'd be interested to know what technology that would be used to detect an overspeeding event as it's happening and before critical speeds are reached.

I've seen some nasty results of overspeeding steam turbines and despite the protections built into that sort of gear, massive failures have occurred.

I'm only guessing, but I'd imagine that whatever dataloggers are installed, might've shown a vertical line on the trend or graph as the engine accelerated. Even if fuel is shut off instantly there's still the momentum, isn't there?

 

[jb747]

Do you know what speed that the turbine reached?


I'd be interested to know what technology that would be used to detect an overspeeding event as it's happening and before critical speeds are reached.

I've seen some nasty results of overspeeding steam turbines and despite the protections built into that sort of gear, massive failures have occurred.

I'm only guessing, but I'd imagine that whatever dataloggers are installed, might've shown a vertical line on the trend or graph as the engine accelerated. Even if fuel is shut off instantly there's still the momentum, isn't there?

I don't know how fast it got...but it's probably in the ATSB report somewhere. Whether a shutdown system could possibly be fast enough to have any effect, I don't know...but RR and co went to the trouble of installing it, so I guess for some scenarios it must work.

I'm sure it's a great idea too, but I wonder how long it will be before it's implicated in an unnecessary shutdown. Many of the protections have shown themselves to have a dark side.

 

[mjt57]

I'm sure it's a great idea too, but I wonder how long it will be before it's implicated in an unnecessary shutdown. Many of the protections have shown themselves to have a dark side.

Yep, seen that first hand at work. All it needs is a failed sensor, loose wire, dry solder joint, incorrect protection setting, whatever...

But the aero industry is several levels above what we do in terms of engineering. So, I'd be reasonably confident that they'd get it right, til the first time it goes wrong, I s'pose...

 

[AVC]

But the aero industry is several levels above what we do in terms of engineering. So, I'd be reasonably confident that they'd get it right, til the first time it goes wrong, I s'pose...

Like the aerospace industry?
Tell that to the Challenger crew.

If an engineer can design it. It can break.

Sort of like calling Alcatraz escape proof.


To continue a previous question...
Why would you not want a spinning wheel in the bay? Obvious reason..too close to exposed hydraulic and electric lines?

Is this fairly new? Would a 747 classic for instance have the sensors to know a wheel had no retract braking. Did they even have retract braking then?

 

[sjd]

The arrival over Essendon places the aircraft high as you pass over the airfield, and requires a greater than usual rate of descent on the base leg. This flies in opposition to the world wide trend towards making approaches with a constant descent angle. It's also only viable with a cloud base of greater than 2,500 feet, and becomes quite limiting if the wind has any easterly component. Whilst a reasonable enough arrival for the domestic blokes to be flying, 'cos they do it day in and out, it's a very poor choice for an international crew who are at the end of a 15 hour sector.

Just watched OQI come in on QF94 on this approach whilst walking the dog this morning in Pascoe Vale (me, not the plane). Great view of the bird and I could just see her banking over East Keilor before disappearing behind the rooftops. Is their an operational reason for ATC specifying this approach for the big birds and can you say no thanks, I'll take a more southerly approach after 15 hours I'd like to keep it simple?

 

[jb747]

To continue a previous question...
Why would you not want a spinning wheel in the bay? Obvious reason..too close to exposed hydraulic and electric lines?

Is this fairly new? Would a 747 classic for instance have the sensors to know a wheel had no retract braking. Did they even have retract braking then?

Retraction braking has existed on every airliner that I have flown. Even in the A4 we used to touch the brakes before retracting the gear.

 

[jb747]

Just watched OQI come in on QF94 on this approach whilst walking the dog this morning in Pascoe Vale (me, not the plane). Great view of the bird and I could just see her banking over East Keilor before disappearing behind the rooftops. Is their an operational reason for ATC specifying this approach for the big birds and can you say no thanks, I'll take a more southerly approach after 15 hours I'd like to keep it simple?

The arrival is convenient for ATC (though I'm not sure why). You can outright knock it back, or as sometimes happens when you say you won't do it, ATC will offer a lower crossing height over Essendon, which has the effect of putting you back into the normal slot. QF banned it for the 747 and 380 for a period after the 777 incident, but it's now available again. They had a good look at it, and placed it on one of the sim scripts, and turned it back on once everyone had been through.

 

[mikenz]

The twins all have better power to weight ratios than do the quads. The simple reason is that a twin (737,767, 330, etc) can have a single engine fail, and it will lose half of the available power, but it still has to be able to fly away from V1 on the runway. In the four engined aircraft, the failure of a single engine, only removes a quarter of the power, so it does not need anywhere near as much 'excess' power in the all engine case. The quads won't fly away in most cases of loss of a second engine on the runway..

What happens in the event of an engine failure on the runway? Assuming you've decided to continue with takeoff do the other engines automatically increase power to make up for the lost engine or is that something you need to do?

 

[Melburnian1]

Oh dear. So you're accusing me of being racist because I don't like the way some safety authorities are subject to management by the judiciary.

The French and Italian legal systems differ markedly from the British tradition to which we are used in Australia.

 

[jb747]

What happens in the event of an engine failure on the runway? Assuming you've decided to continue with takeoff do the other engines automatically increase power to make up for the lost engine or is that something you need to do?

Below V1, you stop. Otherwise you continue. The calculation of take off derate allows for the loss of an engine in the after take off performance, so in theory at least, you don't need to increase the power. Any power increase is manual, never automatic. The thrust during the take off roll is basically locked (in the Boeing, for instance, power is actually removed from the thrust lever servo). An increase of thrust at the wrong time would make the engine out asymmetry even worse, so if you do decide to increase the thrust you wait until you have the aircraft stabilised.

 

[under the radar]

just heard on ABC24...OZ regulations will require 2 people on flight deck at all times..effective immediately they report.. My view on this is the same as jb747s so I won't say anything further.

 

[eric2011]

Below V1, you stop. Otherwise you continue.

If V1 is the stop/go point, if you were to lose an engine just prior to that point, how is reverse thrust affected and the minor braking it produces allowed for in calculations (if at all)

 

[por930]

just heard on ABC24...OZ regulations will require 2 people on flight deck at all times..effective immediately they report.. My view on this is the same as jb747s so I won't say anything further.

I think the general public will be expecting this to happen. In the A380, A toilet and rest area for the relief crew are in the flight deck area, so should not be an issue where more than 2 flight crew on that leg. Maybe a bit more problematic for all short haul. But, after my trip to the states, they have a swap over system for FA's and works well. Though not sure how effective it will be!!!

 

[jb747]

If V1 is the stop/go point, if you were to lose an engine just prior to that point, how is reverse thrust affected and the minor braking it produces allowed for in calculations (if at all)

Reverse thrust is never allowed for, and any that you may have is considered a bonus.

 

[jb747]

I think the general public will be expecting this to happen. In the A380, A toilet and rest area for the relief crew are in the flight deck area, so should not be an issue where more than 2 flight crew on that leg. Maybe a bit more problematic for all short haul. But, after my trip to the states, they have a swap over system for FA's and works well. Though not sure how effective it will be!!!

The question now is, "who watches the watchers?". As I said elsewhere, it makes no difference who is, or isn't in the coughpit, but now we throw another unknown into the mix. So, this appears to do something, but in reality, it does very little.

The real fix is to have the toilets behind the security door, but airlines haven't done this, as it removes one from the cabin. In some cases, the only business class toilet.

The 380 is not immune to this, only the 747-400.

 

[por930]

JB, you are correct..."who watches the watchers", the issue becomes never ending as the third party could have issues as well and as seen in the German wings incident, if people want to, they can hide their health issues to an extent.

Considering the many thousands of flights each day with no problem, this has to be kept in perspective. I can't see the airlines giving up paying seats to build a better secure area for the pilots, especially in the short haul aircraft. A solution would be to build a secure toilet in the forward galley, and then cater from the back galley for business class people. Very inconvenient, and maybe better than removing the business class J toilet...if the airlines want to get serious about a solution then a cabin redesign will not be cheap...nor in the very near future.

Now it seems every one is looking over their shoulder, and unfortunately, where a security weakness exists, some one will always exploit it.

 

[por930]

Jb, have you ever been a passenger in the A380? and do you simply relax and do what ever, knowing the guys up front are very capable. Does your concentration wander some times on departure and or approach and you picture what is happening up front, thinking,,,yes, that's about right?

 

[jb747]

Jb, have you ever been a passenger in the A380? and do you simply relax and do what ever, knowing the guys up front are very capable. Does your concentration wander some times on departure and or approach and you picture what is happening up front, thinking,,,yes, that's about right?

I've been a passenger on all of the company aircraft. I take very little interest in what is happening, and settle, very easily, into passenger mode.

 

[legroom]

I've been a passenger on all of the company aircraft. I take very little interest in what is happening, and settle, very easily, into passenger mode.

If you are not paxing, but purely a touristy passenger on QF flights, how often does anyone know of your status in the company ?

Would the captain recognize his colleague from the manifest ?

CSM bumps you up to F on long haul ?

Professional courtesy, in other words

The question now is, "who watches the watchers?". As I said elsewhere, it makes no difference who is, or isn't in the coughpit, but now we throw another unknown into the mix. So, this appears to do something, but in reality, it does very little.

The real fix is to have the toilets behind the security door, but airlines haven't done this, as it removes one from the cabin. In some cases, the only business class toilet.

Could the pilots learn off the Apollo astronauts something / anything ?
(tongue in cheek)

 

[Welsh-Kiwi]

JB, do you get access to the Chairmans Lounge before a flight if you're working or when you are paxing?