Topic Author
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Forest Fires & Jet Engines

Mon Mar 08, 2004 8:48 pm

Can anyone tell me is it possible to FOD out an FT9-D engine over a fire @ 800 ft??? Has any jet engine ever been FOD out due to forrest fire???

B747-400LCF - B747-200ST!!
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Forest Fires & Jet Engines

Mon Mar 08, 2004 9:18 pm

I'm no engineer, but maybe you get foreburn instead of afterburn  Smile
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Forest Fires & Jet Engines

Mon Mar 08, 2004 9:29 pm

i'll be honest and say i have no idea what u are talking about bookin

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Forest Fires & Jet Engines

Mon Mar 08, 2004 9:44 pm

Fatty Oxidation Disorder on a jet, nah don't think so??

Being serious now, are you talking about like choking the engine? Some one please enlighten us!
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Forest Fires & Jet Engines

Mon Mar 08, 2004 10:04 pm

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.
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Forest Fires & Jet Engines

Mon Mar 08, 2004 10:26 pm

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.
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Forest Fires & Jet Engines

Mon Mar 08, 2004 10:35 pm

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.
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RE: Forest Fires & Jet Engines

Mon Mar 08, 2004 10:43 pm

volcanic ash is highly corrosive so i guess that it would cause seriouse permanent damage to a plane
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RE: Forrest Fires & Jet Engines

Mon Mar 08, 2004 10:51 pm

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.

Kind regards,


[Edited 2004-03-08 14:53:26]
Every landing is a controlled crash
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RE: Forest Fires & Jet Engines

Mon Mar 08, 2004 10:55 pm

I know the ash is abrasive, but is it corrosive too?
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RE: Forest Fires & Jet Engines

Mon Mar 08, 2004 11:04 pm

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 :/
Topic Author
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RE: Forest Fires & Jet Engines

Tue Mar 09, 2004 6:03 pm

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

 Smile 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).

Vulture Strike on 747

View Large View Medium
Click here for bigger photo!

Photo © Barry Byrne

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!!
B747-400LCF - B747-200ST!!
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RE: Forest Fires & Jet Engines

Tue Mar 09, 2004 6:54 pm

I have to admit the Delta L1011 eating a container is pretty darn funny!
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