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Niallo
18th May 2018, 01:08
Fume events, with adverse effects on crew and passengers, are gaining more attention.
I am wondering:
Can the flight crew identify which engine is responsible if they believe the fume event is due to bleed air contamination?
Can they shut off the bleed air from that engine, or if not, are they permitted to shut that engine down?
Niallo (SLF)

AmarokGTI
18th May 2018, 05:21
Fume events, with adverse effects on crew and passengers, are gaining more attention.
I am wondering:
Can the flight crew identify which engine is responsible if they believe the fume event is due to bleed air contamination?
Can they shut off the bleed air from that engine, or if not, are they permitted to shut that engine down?
Niallo (SLF)

I can only speak for the type I fly (Regional Turboprop).

Bleed Air Leak can be identified by the warning system. We then isolate both bleed supplies on that side. If the bleed supplies canít be isolated (system fault) then shut the engine down.

One other problem with a bleed air leak can be that the air is so hot that it can eventually cause structural damage/failure.

wiggy
18th May 2018, 14:43
I might be wrong (as usual) but isn’t the OP is asking about fumes and smells in the cabin...detected by the mark one nose, etc, rather than a Bleed Air duct Leak which as you rightly say is usually detected in some manner by the aircraft warning system?

vilas
18th May 2018, 16:15
In Airbus there is a SMOKE/FUMES/AVIONICS SMOKE Procedure and that will guide the pilot through various steps. There is no step to shut the engine because the fumes/fuel vapours can only come through packs so putting the packs off is enough.

AmarokGTI
18th May 2018, 16:35
I might be wrong (as usual) but isnít the OP is asking about fumes and smells in the cabin...detected by the mark one nose, etc, rather than a Bleed Air duct Leak which as you rightly say is usually detected in some manner by the aircraft warning system?

ah, yep. On re read it does seem pretty clear that is what they are asking. My mistake.

wiggy
18th May 2018, 16:45
Similar checklist for (at least some) Boeing’s: there isn’t a specific oily fumes checklist, there is a catch all “Smoke, Fire or Fumes” checklist which appears to run along the lines described by vilas for the ‘bus in it’s logic - again it’s case of working through various systems (electrics and air supply) to find a cause, so that could involve selectively isolating parts of the bleed air plumbing and possibly shutting down air conditioning “packs”. No shutting down of engines.

Niallo
19th May 2018, 22:23
Thx for replies. I am still wondering how you identify which engine bleed air to isolate when engine fumes are suspected..
If the cabin crew detect the smell before the flight deck crew (or vice versa) does that indicate the engine?
Then does that indicate which pack to shut down, or is there bleed air crossfeed upstream of the packs?
Or is it simply a matter of shutting down each pack in turn and noting any improvement?
Thank you for your patience. My questions are aimed at finding out how quickly the crew can recognise, identify, and shut off the contaminated air supply, and thereby limit their, and the passengers, exposure to the fumes.
Niallo

vapilot2004
19th May 2018, 23:05
On all Boeing twins, the flight deck is the only area that receives air directly from its respective pack (L). While there is recirculated air in the overall system, the plenum pressure is such that only air from the pack goes to the flight deck outlets. Therefore, if there is an abnormal smell emanating from the outlets up front, we may (uncharacteristically) isolate the LEFT pack first.

Smoke events generally require the same steps on most aircraft. Roughly we: de-energize non-essential electrical loads and isolate electrical busses, switch RECIRCULATION FANS OFF, then, if the source is not pinpointed by crew, the next steps are to: ISOLATE BLEED sources, RIGHT PACK OFF, wait to see if air clears. If no change, R PACK ON, then LEFT PACK OFF and wait and see if there's improvement.

The next stage is smoke removal which involves configuring the aircraft equipment cooling and pressurization outflow valves for maximum air exchange. The goal is having all of the above accomplished within 5-6 minutes, if possible.

krismiler
20th May 2018, 04:51
The BAE146 has featured prominently in fume events, even to the extent that crew have retired on medical grounds. The manufacturers simply didn't anticipate the occurrence of contaminated air beyond the usual electrical smoke or other obvious possibilities so there isn't really a set down procedure specifically for it. It's supposed to fall under the generic SMOKE/FIRE/FUMES checklist.

In the early days of jet flying, the FAA didn't permit engine bleed air to be used for cabin pressurisation, the B707 had compressors mounted on top of engines 2,3 and 4. The DC8 had them in the nose.

Niallo
21st May 2018, 23:35
Thanks for the detailed info. Somewhat reassuring that a fume event can be quickly recognised and the source isolated. Niallo