Norwegian 787 blows a donk in FCO
Join Date: Aug 2015
Location: UK
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
I believe bleed air has to be cooled before entering the cabin, which under some conditions could condense some of the water content out resulting in the low humidity experienced (building air conditioning plants will cool air below the target and then warm it back up to ensure it isn't too humid). I'm guessing the 787 cabin compressors don't heat the air so much, so perhaps lose less moisture this way? But I can't imagine them carrying a tank of water to actively humidify the air?
Join Date: Jul 2002
Location: Confusio Helvetica
Posts: 311
Likes: 0
Received 0 Likes
on
0 Posts
787s have humidifiers for flight deck and crew rest air. Something like that is being done on the A350 and 777X as well, with humidification of first and business as on option. For the most part, the cabin experience is the same.
The colder the air, the less moisture it can hold, so if you cool air with nonzero relative humidity, the resulting air will have a higher relative humidity, which is why air conditioners have dehumidifiers. If you warm air, the result has a lower relative humidity. If the air outside is -40, heating it to room temperature is going to create a very dry environment that sucks the water out of you. This has nothing to do with bleed air or electrically heated.
There's also the claim when the 380 and 787 were entering service that they're pressurized to 6000 feet, while previous gen ac are pressurized to 8000. I'll leave it to someone else to say how often their Cabin Alt climbs to 8000.
The colder the air, the less moisture it can hold, so if you cool air with nonzero relative humidity, the resulting air will have a higher relative humidity, which is why air conditioners have dehumidifiers. If you warm air, the result has a lower relative humidity. If the air outside is -40, heating it to room temperature is going to create a very dry environment that sucks the water out of you. This has nothing to do with bleed air or electrically heated.
There's also the claim when the 380 and 787 were entering service that they're pressurized to 6000 feet, while previous gen ac are pressurized to 8000. I'll leave it to someone else to say how often their Cabin Alt climbs to 8000.
Hasn't the claim been the humidity could be set higher because of the CFRP fuselage? Like less corrosion risk or similar?
Given the issues with the Trent I'm surprised this has not caused more of a stir.
Was this a mechanical failure of the engine, a precautionary shutdown, or was there an external cause?
Was this a mechanical failure of the engine, a precautionary shutdown, or was there an external cause?
Join Date: Dec 2006
Location: Florida and wherever my laptop is
Posts: 1,350
Likes: 0
Received 0 Likes
on
0 Posts
I’ve never seen a birdstrike cause anything like this. Damage yes, but a spray of engine parts out the back? 25 houses and 12 cars damaged by falling parts. Norwegian says this is an ongoing investigation and doesn’t want to comment.
If this is a modified engine as somebody said, it’s really bad news for operators with these engines.
Add the fact that engine pairs have about the same number of hours and I for one would be reluctant to go on an aircraft with these engines.
The modifications are about fanblades/turbine blades?
What they were able to do on the 787 - that hadn't been done previously - was have humidifiers to improve the humidity of the passenger (and crew) air. The carbon fiber construction meant there is no corrosion risk associated with that, but the ability to add humidifiers for passenger comfort has always been there - just seldom used.
It's up to the operator as to if they bother to service the humidifiers with water between flights...
BTW, for all the problems the Trent 1000 has been having, the current generation of engines is still an order of magnitude more reliable than what was available 40 years ago. Back then, people thought a shutdown every 10,000 hours was just fine, today a shutdown every 100,000 hours is cause for concern.
787 Humidity
Zonal driers in the crown area stops the moisture from condensing out, it is then recirculated back into the cabin to keep the humidity level above 15%.
At least, thats the theory.
Back to exploding engines....
At least, thats the theory.
Back to exploding engines....
Join Date: Feb 2018
Location: Devon
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Indeed it did have Godfrey engine driven compressors, just like the Viscount! The VC10 ones had variable output controlled by a slide valve which often leaked huge quantities of oil into the a/c ducting. Nothing new....
Thread Starter
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
What was acceptable 40 years ago is not acceptable today. 180 minutes ETOPS with possible dodgy engines...😮
Join Date: Aug 2019
Location: Brexland
Posts: 212
Likes: 0
Received 0 Likes
on
0 Posts
I think people are getting caught up in Boeing spin here, our 30 year old 757s regularly cruise along at 6000 feet cabin altitude but our 737s sit at 8000 at the same level. Both use standard engine bleed as far as I'm aware
When you have an engine with known issues and that engine starts to spew engine parts out the back, I lean towards a connection between the two. And that can mean really bad news for operators of these engines. If taking them off the aircraft for modifications doesn’t solve the problem...
What was acceptable 40 years ago is not acceptable today. 180 minutes ETOPS with possible dodgy engines...😮
Big pieces typically equate to loose larger bits which often stem from the cooler parts in a turbine. I was under the impression that the earlier publizied problem was in the hot part of the turbine.So I remain neutral in picking a cause out of a news item.
Thread Starter
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
Once again association does not equal causation.
Big pieces typically equate to loose larger bits which often stem from the cooler parts in a turbine. I was under the impression that the earlier publizied problem was in the hot part of the turbine.So I remain neutral in picking a cause out of a news item.
Big pieces typically equate to loose larger bits which often stem from the cooler parts in a turbine. I was under the impression that the earlier publizied problem was in the hot part of the turbine.So I remain neutral in picking a cause out of a news item.
Join Date: Jan 2007
Location: Second star to the right, and straight on 'til morning
Age: 63
Posts: 513
Likes: 0
Received 0 Likes
on
0 Posts
I'm surprised how little factual information has been released about this incident, especially given the history of problems with the Trent on the 787. The only photo of the affected engine I could find had a large advertising board placed in front of it to try to prevent photos of the damage. Normally, by this stage, we would have seen photos of the damaged engine, know the variant of the engine, the number of cycles and hours it had done, and have some idea about what part of the engine had failed, even if the cause is still to be determined.
Twitter had this amusing observation;
Twitter had this amusing observation;
As avgeeks like @janlisiecki most likely know: BOEING = Bits Of Engines In Neighbor‘s Garden
Join Date: Jan 2013
Location: Right hand seat of a 777
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
What about ANZ 787 that decided it needed to loose a few KG's on departure from AKL (I think it was) , didn't that shower the local community with fan blades?
Thread Starter
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
It would be interesting to see pictures of the Norwegian FCO incident engine and how it compares to the ANZ one. Both sprayed parts out the back.
https://www.newsroom.co.nz/2017/12/0...ed-787-engine#
Your 757’s are a bit different than ours. At the same altitude the 757 would have a lower cabin altitude because of how it was scheduled but they typically cruised much higher so the actual cabin altitude was the same. All the Boeing older airframes had the same max differential pressure. The 787 is pressurized to a higher differential pressure than earlier Boeing’s and can maintain 6000 feet you FL430.