Oooh look,
I can use google if the advice isn't in my ops manual, its supplements or my manufacturer's training material. So for those who need spoonfeeding.
Aero 09 - Volcanic Ash Avoidance
It's a very good article but here are the essentials:
Recognition.
Indicators that an airplane is penetrating volcanic ash are related to
odor, haze, changing engine conditions, airspeed, pressurization, and
static discharges.
* Odor. When encountering a volcanic ash cloud, flight crews
usually notice a smoky or acrid odor that can smell like
electrical smoke, burned dust, or sulfur.
* Haze. Most flight crews, as well as cabin crew or passengers,
see a haze develop within the airplane. Dust can settle on
surfaces.
* Changing engine conditions. Surging, torching from the tailpipe,
and flameouts can occur. Engine temperatures can change
unexpectedly, and a white glow can appear at the engine inlet.
* Airspeed. If volcanic ash fouls the pitot tube, the indicated
airspeed can decrease or fluctuate erratically.
* Pressurization. Cabin pressure can change, including possible
loss of cabin pressurization.
* Static discharges. A phenomenon similar to St. Elmo?s fire or
glow can occur. In these instances, blue-colored sparks can
appear to flow up the outside of the windshield or a white glow
can appear at the leading edges of the wings or at the front of
the engine inlets.
[Let's take a break from the difficult stuff shall we?] Some displays of St Elmos Fire on Youtube at
YouTube - St. Elmos Fire in a A319 from cockpit - Now we return to the bits where you have to think.
Procedures.
The following nine procedures are general recommendations. Each
operator's flight operations manuals will include more specific
directions.
1. Reduce thrust to idle immediately. By reducing thrust, engines
may suffer less buildup of molten debris on turbine blades and
hot-section components. Idle thrust allows engines to continue
producing electrical power, bleed air for pressurization, and
hydraulic power for airplane control.
2. Turn the autothrottles off. This prevents the engines from
increasing thrust above idle. Ash debris in the engine can
result in reduced surge margins, and limiting the number of
thrust adjustments improves the chances of engine recovery.
3. Exit the ash cloud as quickly as possible. A 180-deg turn out of
the ash cloud using a descending turn is the quickest exit
strategy. Many ash clouds extend for hundreds of miles, so
assuming that the encounter will end shortly can be false.
Climbing out of the ash could result in increased engine debris
buildup as the result of increased temperatures. The increased
engine buildup can cause total thrust loss.
4. Turn on engine and wing anti-ice devices and all
air-conditioning packs. These actions improve the engine stall
margins by increasing the flow of bleed air.
5. If possible, start the auxiliary power unit (APU). The APU can
power systems in the event of a multiple-engine power loss. It
can also be used to restart engines through the use of APU bleed
air.
6. If volcanic dust fills the flight deck, the crew may need to use
oxygen. Use flight deck oxygen at the 100 percent setting.
Manual deployment of the passenger oxygen system is not required
because it will deploy automatically if the cabin altitude
exceeds 14,000 ft.
7. Turn on the continuous ignition. Confirm that autostart is on,
if available. In the event that the engines flame out or stall,
use appropriate procedures to restart the engines. During
restart, the engines may take longer than normal to reach idle
thrust due to the combined effects of high altitude and volcanic
ash ingestion. If an engine fails to start, try restarting it
again immediately. Flight crews should remember that the
airplane may be out of the airstart envelope if the encounter
occurs during cruise.
8. Monitor engine exhaust gas temperature (EGT). Because of
potential engine debris buildup, the EGT can climb excessively.
The flight crew should prevent EGT exceedances. Shut down the
engine and restart it if the EGT is approaching limits similar
to a hung start.
9. Fly the airplane by monitoring airspeed and pitch attitude. If
necessary, follow the procedure for flight with unreliable
airspeed.
Finally, click here to see photos of F18 engine parts following test flights on Thursday 15th before any of Finnish airspace was declared unsafe.
(
Puolustusvoimat - Frsvarsmakten - The Finnish Defence Forces)
Rob