DfwRevolution From United States of America, joined Jan 2010, 962 posts, RR: 51
Reply 4, posted (10 years 4 months 3 weeks 3 days 2 hours ago) and read 6772 times:
A British Airways 747 did loose all 4 engines after flying through a cloud of volcanic ash, but was able to restart an engine and land. I don't know if the density of ash/soot in a forest fire could shutdown an engine, but it's a good question.
Zak From Greenland, joined Sep 2003, 1993 posts, RR: 8
Reply 5, posted (10 years 4 months 3 weeks 3 days 2 hours ago) and read 6720 times:
i would guess that this would not affect the engines at all considering in forest fires you only have a small amount of ash in the smoke compared with the amount, density and size of vulcanic dust and ash in a vulcanic plume.
volcano clouds play in a whole different league, their "clouds" are formed mainly due to the mass of matter that is ejected from the earth, i.e. there is actually a process where huge amounts of matter are constantly "generated" (or pumped up by the volcano to be exact. the clouds there are usually vulcanic gasses and byproducts of the eruption that are light enough.
the majority of a volcanic eruption is in many cases actually erupted directly into the atmosphere, for example the krakatau explosion left vast areas of the ocean(hundrets of km²) covered with swimming pumices and also left over a metre of dust on the deck of ships 50 or more kilometres away.
compared to that the smoke from a forest fire is mostly water vapour and rust. i would guess the amount of rust and other particles emitted by a large forest fire overall would not be over a few thousand tons, and that over a few days and a rather large area.
compared to the typical emission of millions(and in rare cases) billions of tons of dust and particles emitted into the atmosphere by eruptions, packed into a very dense and thick cloud, should lead to the conclusion a forest fire cloud that is really mostly vapour etc should not affect the engines too much, even though i am sure there is a measureable drop in performance during the flythrough due to the lower amount of oxygen.
Wannabe From United States of America, joined Jun 1999, 677 posts, RR: 3
Reply 6, posted (10 years 4 months 3 weeks 3 days 2 hours ago) and read 6690 times:
I don't think that there is enough particulate matter in forest fire smoke to FOD (Foreign Object Damage) an engine. A volcano is another story, both in the size of the cloud and the amount of ash suspended in it. I read the BA event, and in that case, they were flying through a major eruption at night without even realizing it. We all know how abrasive pumice is....imagine flying through a 20+ mile cloud of it. It sandblasted the windshield opaque, and covered most of the leading edge surfaces with almost an inch of powder. It also beat the engines to death. All 4 flamed out. They were able to get them restarted once they cleared the cloud, but lost one or two right after that. I don't remember the exact details I read about this event in a book that I lent to someone and.....well, you know the story about lending books. But in any case, I just don't think a forrest fire could place that level of material in the air.
KLM777 From Netherlands, joined Dec 2003, 372 posts, RR: 0
Reply 8, posted (10 years 4 months 3 weeks 3 days 1 hour ago) and read 6639 times:
As long as you don't fly through the ash clouds, it's possible I guess. Possible, but not preferable IMHO. The big ash clouds will be visible, but you cannot really tell whether there is ash flying around outside these clouds. The danger I think is that when you've flow through the nearly invisible ash and your engines stop, there's little to no margin to restart them or make a safe landing (as you're above the forest).
The incidents with volcanic ash clouds worked out well (apart from the BA747 incident Dfwrevolution mentioned, there was another incident on a KLM747 near Anchorage) because they were at cruise level, and they could safely glide out of the ash clouds.
Apart from whether it's possible or not, I think the damage done to the engines because of the ash going through becomes very expensive to repair after a few flights. It's more economical to get two C-130 instead.
Zak From Greenland, joined Sep 2003, 1993 posts, RR: 8
Reply 10, posted (10 years 4 months 3 weeks 3 days 1 hour ago) and read 6597 times:
depends on the ash, but certain types of volcanic gas do form hydrochlorid and other acids upon contact with humidity. i would guess there are various scenarios where vulcanic gas/ash would be corrosive or react to something corrosive.
AFAIK, most volcano photographers take gas masks with them to ensure they have them ready incase they encounter acidic clouds and other potentially dangerous gases. imagine the feeling of vulcanic gas reacting to hydrochlorid acid with the humidity of your mouth, nose and respiratory system. i would guess that would be a thrilling experience :/
Bookin From United States of America, joined Feb 2004, 75 posts, RR: 0
Reply 11, posted (10 years 4 months 3 weeks 2 days 6 hours ago) and read 6457 times:
FOD is foreign object debris, like the 16-inch piece of stray metal believed to have caused the Air France Concorde crash outside Paris that killed all 109 people on board and four on the ground.
FOD from volcanic ash is not pertinet to this thread. That stuff is nasty! Corrossive, abrassive, engine killer!
Forrest fire ash is probably not as bad as the limbs, embers and other debris spewed up from fires. I've heard debris spewed by fires can be found upwards of 1000'. Can anybody confirm this?
In aviation, FOD means Foreign Object Damage, e.g., what happens when a jet engine sucks up a rock on the runway or a bird in flight. Finger of Death is actually a good description of what this generally does to the engine.
There are many other uses of the acronym FOD:
Fax on demand
Field of dreams
Fatty Acid Oxidation Disorder
Friends of Dorothy Travel
Frank O'Dwyer's Security Sources
Finger of Death
Finishing on Demand
Forest of Dean Diet
Fighters of the Death
Fog of Deception
Sorry fo getting tooo technical with my inital post.
Here's some good example pics of ummm.. big ass FOD
Biting off more than one can chew.
This would have come to a different end with a 777!
The story from Delta on the LD-3 FOD is that the container was sitting on the ramp, the L1011 was at
idle when a company B757 starting to taxi away and blew the LD-3 across the ramp. I suppose the LD-3
would have gone right through the engine if it hadn't just been idling! Damage was minimal to the engine (just the inlet).
This is what happened to #4 engine on an Evergreen 747F in Nairobi, Kenya back in 1997. They had to dump a lot of fuel and return to Nairobi. After replacing the entire engine with a new one, another bird was sucked into the #2 engine during take-off roll! A week later!!