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PA46 Malibu N264DB missing in the English Channel

I take it you have a source of air that doesn’t go anywhere near the engines?

kwlf wrote:

I take it you have a source of air that doesn’t go anywhere near the engines?

Well you have an oxygen mask with O2 from a bottle, and once the cabin pressurisation is switched off and dumped there is nothing coming from the engine areas.

However in our incident the root cause was electrical smoke from a fan motor which was under the floor underneath the pilot’s feet. We actually opened up the DV window when we were depressurised, as well as switching off all the electrics.

Darley Moor, Gamston (UK)

kwlf wrote:

I take it you have a source of air that doesn’t go anywhere near the engines?

As Neil says, you actually don’t other than O2. All bleed air comes from the engines but upstream from the hot section where the fuel is burnt.

Last Edited by JasonC at 19 Aug 19:45
EGTK Oxford

Though that’s presumably in jet engines rather than pressurised piston aircraft.

To cover the cabin pressure technology the systems I have encountered are as follows

jet engines Engine compressor bleed, usually from around the 8th stage of the compressor backed up by 13th stage for low RPM situations ( B737, A320, BAC 1-11, HS trident B747)

Turbo compressor, the engine bleed air was used to drive a cabin compressor ( B707 )

Cabin compressor, a compressor driven from the engine gearbox ( L188, VC10 )

Electrically driven compressor ( B787 )

piston engines Bleed from an overly large engine turbocharger ( GA aircraft ) Cabin compressor on some large piston engine airliners with supercharged engines.

Most of these systems are very reliable but you could see why engine bleed air was a favourite with the aircraft manufacturers, I spent four weeks in the VC10 cabin compressor overhaul shop when I was an apprentice and I can only describe the unit as mechanically complicated and skilled labour intensive to set up correctly so very expensive.

Interesting to see that the source for pressurised air in jets is returning, after decades of it being bleed air, to separate compressors.

Why is that? My guess is engine efficiency (higher EPR with no bleed air), and hence fuel savings, to justify the cost of the additional compressor.

Biggin Hill

I think that few story rose where few crew were sick by strange odor in the cabin as they are continuously in contact with oily air, apparently minor oil leak in compressor stage where main bleed comes from. I’m happy that in 787, pressurisation bleed comes from a separate device away from motor. But it is new system, prone to issue and must be lubricated anyway.

LFMD, France

Some stuff reverberating around the noble House of Lords over N-reg illegal charters

https://hansard.parliament.uk/Lords/2020-02-10/debates/2338BEBE-308C-4BCF-8C87-EBEB669F0093/AirAccidentInvestigation

Administrator
Shoreham EGKA, United Kingdom

Looks like you might have to go over to G reg Peter!

Egnm, United Kingdom

Actually with wingly etc there are way more “illegal charters” under G-reg than under N-reg. If I was doing something illegal I would deffo be G-reg (with a valid number) because nobody will notice it.

But, yeah, this sad accident was going to kick up a lot of mud which is useful ammo for the “usual crowd”.

Administrator
Shoreham EGKA, United Kingdom
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