Mt. Saint Helens

[C J Campbell]

Scientists are now predicting a 70% chance of Mt. Saint Helens erupting and
throwing rocks as far as three miles away. Pilots flying in the area should
steer clear of the crater.

--
Christopher J. Campbell
World Famous Flight Instructor
Port Orchard, WA


If you go around beating the Bush, don't complain if you rile the animals.

[BTIZ]

that would be one heck of a thermal ride... if it weren't for the rocks...
and "cough cough" the ash..

BT

"C J Campbell" > wrote in message
...
> Scientists are now predicting a 70% chance of Mt. Saint Helens erupting
and
> throwing rocks as far as three miles away. Pilots flying in the area
should
> steer clear of the crater.
>
> --
> Christopher J. Campbell
> World Famous Flight Instructor
> Port Orchard, WA
>
>
> If you go around beating the Bush, don't complain if you rile the animals.
>
>
>

[Philip Sondericker]

in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
wrote on 9/30/04 7:00 PM:

> that would be one heck of a thermal ride... if it weren't for the rocks...
> and "cough cough" the ash..
>
> BT

I was thinking about this recently, and I was trying to determine exactly
what the effects would be on a small plane flying into an ash cloud. How
long would it take for the air filter to become completely clogged? And at
that point, assuming the plane had a carburetor, what would be the effect on
the engine? Would the plugs become fouled? Would they fire at all?

I'm a new pilot and relatively ignorant of engine operations, so I'm curious
to hear the answers.

[NW_PILOT]

I know if it dose go I will be up taking photos.


"BTIZ" > wrote in message
news:fT27d.3595$mS1.2578@fed1read05...
> that would be one heck of a thermal ride... if it weren't for the rocks...
> and "cough cough" the ash..
>
> BT
>
> "C J Campbell" > wrote in message
> ...
> > Scientists are now predicting a 70% chance of Mt. Saint Helens erupting
> and
> > throwing rocks as far as three miles away. Pilots flying in the area
> should
> > steer clear of the crater.
> >
> > --
> > Christopher J. Campbell
> > World Famous Flight Instructor
> > Port Orchard, WA
> >
> >
> > If you go around beating the Bush, don't complain if you rile the
animals.
> >
> >
> >
>
>

[Orval Fairbairn]

In article >,
Philip Sondericker > wrote:

> in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
> wrote on 9/30/04 7:00 PM:
>
> > that would be one heck of a thermal ride... if it weren't for the rocks...
> > and "cough cough" the ash..
> >
> > BT
>
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect on
> the engine? Would the plugs become fouled? Would they fire at all?
>
> I'm a new pilot and relatively ignorant of engine operations, so I'm curious
> to hear the answers.
>


You can count on an early overhaul, at best. During the 1980s, several
turbine aircraft, including a B747, encountered ash clouds in flight.
The ash is so abrasive that it eroded the compressors to the point of
flameout. The B747 descended to ~10000 ft before they got three engines
relit. A C130 had similar problems.

In a piston engine, the alternate air door would probably open, allowing
unfiltered air into the engine. I p-robably wouldn't atop, but the
compression test would be pretty grim.

[Ross Oliver]

Orval Fairbairn > wrote:
>
>You can count on an early overhaul, at best. During the 1980s, several
>turbine aircraft, including a B747, encountered ash clouds in flight.
>The ash is so abrasive that it eroded the compressors to the point of
>flameout. The B747 descended to ~10000 ft before they got three engines
>relit.


June 24, 1982, a British Airways 747 over Java.

The ash cloud also sandblasted the windshield nearly opague.
The flight crew had great difficulty making out the approach and
runway lights to land the aircraft. If the incident had occurred
during daylight hours, they probably would not have been able
to see out at all.

[Peter Duniho]

"Philip Sondericker" > wrote in message
...
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect
> on
> the engine? Would the plugs become fouled? Would they fire at all?

The Northwest Mountain Division has rearranged things, and I can't find
their article anymore. But sometime back in the 90's, I read a description
on their web site about some consequences of the St. Helens eruption in
1980. The description included a jet that suffered the failure of all
engines, and a lightplane that barely survived.

Here are some articles that address the turbine side of things:
http://www.boeing.com/commercial/aeromagazine/aero_09/volcanic_story.html
http://www.nw.faa.gov/releases/volash.html
I found them looking for the other article I remember.

Anyway, I don't know how long it would take for the air filter to become
clogged, but probably not too terribly long if you flew through the meat of
an ash cloud. Obviously, it depends on how close you get to the densest
part; just skim a side of the cloud, and you might not notice a problem at
all. Go through the middle, and you might clog the filter in a matter of
minutes.

Of course, the next step at that point would be to use the alternate air;
carb heat for carbureted engines, and whatever alternate air source for
fuel-injected (often is an automatically deployed, spring-loaded door that
bypasses the filter when it's clogged). One ingested, the ash would start
eating up the engine, but I would guess that you'd at least have enough time
to get on the ground to make an emergency landing. I think that the plugs
getting fouled would be the least of your worries, but who knows? Maybe the
heat of the spark would cause a nice, insulating glass barrier to form at
the sparkplug gap.

That is assuming, of course, you can still see out of the windows, since
they'll have been sandblasted the whole time. And that you find an area of
visibility high enough to make a landing. If the engine fails before you
can land, then you obviously will be forced to land wherever you happen to
be, regardless of whatever visibility you have.

I gather that generally speaking, other than trashing the airplane, pilots
usually make it out of ash clouds alive. But not all do, and it's certainly
not something I'd want to try, given the option. :)

Pete

[Kees Mies]

Philip Sondericker > wrote in message >...
> in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
> wrote on 9/30/04 7:00 PM:
>
> > that would be one heck of a thermal ride... if it weren't for the rocks...
> > and "cough cough" the ash..
> >
> > BT
>
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect on
> the engine? Would the plugs become fouled? Would they fire at all?
>
> I'm a new pilot and relatively ignorant of engine operations, so I'm curious
> to hear the answers.

The engine is about the last part I would worry about when flying
through a vulcanic ash cloud.
Probably you get burned to death or at least get a bit charred,
together with your plane.

To answer your quistion about the engine.
It will end up ruined, either by crashing or by inhaling to much dust
and then crashing. Or maybe you are lucky and you end up with a nice
sandblasted aircraft.

Some jets have flown through such clouds(they fly much higher, the
cloud is cooler that high), they needed a repaint and have their
engines replaced.


-Kees

[Rich Lemert]

Philip Sondericker wrote:

> in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
> wrote on 9/30/04 7:00 PM:
>
>
>>that would be one heck of a thermal ride... if it weren't for the rocks...
>>and "cough cough" the ash..
>>
>>BT
>
>
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect on
> the engine? Would the plugs become fouled? Would they fire at all?

Considering that a volcano almost brought down a 747 once, I don't
think a small plane is going to last long at all. Of course, the pilot
is going to have been broiled long before he has to worry about his
engine.

Rich Lemert

[G.R. Patterson III]

NW_PILOT wrote:
>
> I know if it dose go I will be up taking photos.

You can get the best shots from directly overhead.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.

[Michael 182]

"G.R. Patterson III" > wrote in message
...
>
>
> NW_PILOT wrote:
>>
>> I know if it dose go I will be up taking photos.
>
> You can get the best shots from directly overhead.

Briefly

>
> George Patterson
> If a man gets into a fight 3,000 miles away from home, he *had* to
> have
> been looking for it.

[C J Campbell]

"Philip Sondericker" > wrote in message
...
> in article fT27d.3595$mS1.2578@fed1read05, BTIZ at

> wrote on 9/30/04 7:00 PM:
>
> > that would be one heck of a thermal ride... if it weren't for the
rocks...
> > and "cough cough" the ash..
> >
> > BT
>
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect
on
> the engine? Would the plugs become fouled? Would they fire at all?

Volcanic ash is very fine, like talcum powder. It is the same abrasive stuff
that they sell in pumice soap that removes anything, including your skin,
from your hands. It gets into everything. Worst case scenario if you flew
into a cloud of it your air filter would become clogged almost instantly. A
lot of the ash might work its way through the filter and into the engine,
where it is going to start abrading all the moving parts very quickly. Using
unfiltered air will just suck huge quantities of ash into the engine. The
cylinders will quickly overheat and the engine will quit. Odds are, though,
it would not be that bad. There are plenty of films of people driving around
in the ash cloud. It isn't smart and most of them suffered engine damage,
but their cars kept running. You might be able to keep a piston airplane
engine running long enough to make it to a safe landing area, but it will
probably suffer some damage.

Perversely, just when you would like to enrichen the mixture in order to
cool the engine and maybe wash some ash out of it, the ash is displacing air
and causing the mixture to be too rich already. As you set up for approach
and landing, you will find brakes, flaps, landing gear, propellers, and
every other moving part clogged with ash, even if you are no longer inside
the cloud. Your alternator may be ground to a pulp and your battery dead, so
you will not have any electrical system anyway. Your prop governor will also
be damaged, as will the oil cooler and anything else that moves. Control
surfaces and cables will be coated with abrasive, sticky ash.

The ash will also simultaneously reduce lift and increase drag. Stall speed
will increase as significant amounts of ash accumulate on and in the
airplane.

You also will be IMC and the cabin will also fill with ash to the point that
you will have difficulty breathing. All surfaces will be sand blasted and
you won't be able to see out the windows once you leave the cloud. It is
very dark inside a volcanic cloud, even darker than night. You cannot see
your hand in front of your face. The whole effect is one of driving around
at night in a very heavy snowstorm and dense fog.

Did I mention the poisonous gases? They aren't concentrated enough to hurt
most people, but asthmatics and others with impaired breathing can be
killed. There will be unhealthy concentrations of CO2, various sulfur
compounds, and acids. They can also damage the airplane. Fortunately they
are pretty well dispersed except in the immediate vicinity of the volcano.

[C J Campbell]

"Rich Lemert" > wrote in message
k.net...
> Philip Sondericker wrote:
>
> > in article fT27d.3595$mS1.2578@fed1read05, BTIZ at

> > wrote on 9/30/04 7:00 PM:
> >
> >
> >>that would be one heck of a thermal ride... if it weren't for the
rocks...
> >>and "cough cough" the ash..
> >>
> >>BT
> >
> >
> > I was thinking about this recently, and I was trying to determine
exactly
> > what the effects would be on a small plane flying into an ash cloud. How
> > long would it take for the air filter to become completely clogged? And
at
> > that point, assuming the plane had a carburetor, what would be the
effect on
> > the engine? Would the plugs become fouled? Would they fire at all?
>
> Considering that a volcano almost brought down a 747 once, I don't
> think a small plane is going to last long at all. Of course, the pilot
> is going to have been broiled long before he has to worry about his
> engine.

Depends on how close you are to the volcano. If you are more than a couple
miles away it won't be that hot inside the ash cloud.

[C J Campbell]

I forgot to mention one other effect of dense ash clouds:

They are warm, unstable, moist (volcanos have a lot of steam), and have a
lot of friction going on inside them. They can generate lightning and
turbulence and just about anything else that goes on inside a severe
thunderstorm, including hail.

[C J Campbell]

One other thing about my previous posts. They assume a small to moderate
eruption, where the ash cloud will not extend more than 100 miles downwind.
Even there, flying through the ash cloud will be like flying through a Texas
sandstorm, not something you would want to do every day.

But suppose the big one hits, like 1980. It will become dark as night as far
east as Idaho. People will be killed by heat and poisonous gases up to 20
miles away. The shock wave will be felt for hundreds of miles. All trees and
structures will be leveled for 20 miles. The ash cloud will travel around
the world several times. The explosive power will exceed that of all the
earth's nuclear weapons combined. You would not want to be anywhere near
such an explosion, in an airplane or anything else.

Mt. Rainier is similar in structure to St. Helens, only bigger and even more
powerful. It has thousands of years of glaciated water built up on its
slopes. It is located in a much more densely populated area. Should it
explode (and it might), loss of life could reach into the hundreds of
thousands and it could well be the worst and most devasting natural disaster
in history. There is some evidence of a prehistoric volcanic explosion at
Yellowstone that reduced the worldwide human population to fewer than a
dozen individuals, but that event has yet to be proven.

[Corky Scott]

On Fri, 01 Oct 2004 02:20:25 GMT, Philip Sondericker
> wrote:

>
>I was thinking about this recently, and I was trying to determine exactly
>what the effects would be on a small plane flying into an ash cloud. How
>long would it take for the air filter to become completely clogged? And at
>that point, assuming the plane had a carburetor, what would be the effect on
>the engine? Would the plugs become fouled? Would they fire at all?
>
>I'm a new pilot and relatively ignorant of engine operations, so I'm curious
>to hear the answers.

I recall reading a first hand experience of exactly what you are
describing. Not positive but I think the pilot was flying an early
Cessna or perhaps a Luscombe or something similar. He was with his
wife and was flying downwind of Mt St Helens and unaware of the
explosion. He was either overtaken by the plume, or flew into it
thinking it was something else and was in immediate and serious
trouble.

He could not see hardly anything and ended up luckily overflying an
airfield on which he had to circle to land, in the otherworldly
darkness and lack of vision. His engine was barely running by this
time and he managed to bump it down and it quit instantly as he
touched down.

My recollection is that the airplane looked like it had been
sandblasted. The paint was gone from the leading edges of the wing
and anything facing into the wind. The windshield was opaque. The
prop was abraided, the air filter was clogged to the point where it
would not pass any air and I seem to remember engine damage.

I also recall him saying that he burst into tears upon getting out of
the airplane as he realised just how close things had been for him and
his wife.

Corky Scott

[Peter Duniho]

"C J Campbell" > wrote in message
...
> [...] There is some evidence of a prehistoric volcanic explosion at
> Yellowstone

Yellowstone is one huge caldera, almost certainly the remains of a large
erupted volcano. This is well-established geological fact.

> that reduced the worldwide human population to fewer than a
> dozen individuals

Never heard that one before. Fewer than 12 people remaining, around the
entire globe you say? Yeah, right. I doubt any scientist with an actual
clue believes that.

> but that event has yet to be proven.

No kidding? I'm shocked.

Pete

[MLenoch]

I was in the St. Helens ash fallout in 1980. I was in a hanger in Wenachee WA
repairing the landing gear of a Steen Skybolt. The ash got into everything.
My car was inside the hanger with the doors & windows closed. The ash got
inside anyway.
In mid morning when the volcano blew, I heard the eruption. I wasn't near any
radio/TV, thus I thought I heard a sonic boom from a passing fighter. A few
hours later the ash came, preceeded by dark clouds like a midwestern fast
moving cold front....little did I know.
VL

[John Clear]

In article >,
Peter Duniho > wrote:
>"C J Campbell" > wrote in message
...
>> [...] There is some evidence of a prehistoric volcanic explosion at
>> Yellowstone
>
>Yellowstone is one huge caldera, almost certainly the remains of a large
>erupted volcano. This is well-established geological fact.
>
>> that reduced the worldwide human population to fewer than a
>> dozen individuals
>
>Never heard that one before. Fewer than 12 people remaining, around the
>entire globe you say? Yeah, right. I doubt any scientist with an actual
>clue believes that.
>
>> but that event has yet to be proven.
>
>No kidding? I'm shocked.

I've never heard the less then a dozen people left, but one of
those Discovery Channel type shows awhile back was on using DNA
markers to trace how humans have moved around and interbred over
the years. One of the things they found was that at one point,
the human population was drastically reduced to ~10,000 people.

John
--
John Clear - http://www.panix.com/~jac

[Dan Luke]

"G.R. Patterson III" wrote:
>
>
> NW_PILOT wrote:
> >
> > I know if it dose go I will be up taking photos.
>
> You can get the best shots from directly overhead.

Now *that's* what I call real, he-man killfiling.
--
Dan
C-172RG at BFM

[lance smith]

Philip Sondericker > wrote in message >...
> in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
> wrote on 9/30/04 7:00 PM:
>
> > that would be one heck of a thermal ride... if it weren't for the rocks...
> > and "cough cough" the ash..
> >
> > BT
>
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect on
> the engine? Would the plugs become fouled? Would they fire at all?
>
> I'm a new pilot and relatively ignorant of engine operations, so I'm curious
> to hear the answers.


Flying through forest fire smoke can roast and asphyxiate you. I'm
assuming volcanic ash is just as hot if not hotter (but possibly with
more oxygen). The air filter and spark plugs will be the least of your
worries at that point : )

-lance smith

[David Brooks]

"Orval Fairbairn" > wrote in message
...
> In article >,
> Philip Sondericker > wrote:
>
> > in article fT27d.3595$mS1.2578@fed1read05, BTIZ at

> > wrote on 9/30/04 7:00 PM:
> >
> > > that would be one heck of a thermal ride... if it weren't for the
rocks...
> > > and "cough cough" the ash..
> > >
> > > BT
> >
> > I was thinking about this recently, and I was trying to determine
exactly
> > what the effects would be on a small plane flying into an ash cloud. How
> > long would it take for the air filter to become completely clogged? And
at
> > that point, assuming the plane had a carburetor, what would be the
effect on
> > the engine? Would the plugs become fouled? Would they fire at all?
> >
> > I'm a new pilot and relatively ignorant of engine operations, so I'm
curious
> > to hear the answers.
> >
>
>
> You can count on an early overhaul, at best. During the 1980s, several
> turbine aircraft, including a B747, encountered ash clouds in flight.
> The ash is so abrasive that it eroded the compressors to the point of
> flameout. The B747 descended to ~10000 ft before they got three engines
> relit. A C130 had similar problems.

New Zealand-based pilots , especially those close to the central range on N
Island, have to deal with ash from time to time. When I visited in 1997, our
747 was sent from Auckland airport an hour early because Ruapehu was acting
up. Any Kiwis here can comment?

-- David Brooks

[SelwayKid]

Philip Sondericker > wrote in message >...
> in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
> wrote on 9/30/04 7:00 PM:
>
> > that would be one heck of a thermal ride... if it weren't for the rocks...
> > and "cough cough" the ash..
> >
> > BT
>
> I was thinking about this recently, and I was trying to determine exactly
> what the effects would be on a small plane flying into an ash cloud. How
> long would it take for the air filter to become completely clogged? And at
> that point, assuming the plane had a carburetor, what would be the effect on
> the engine? Would the plugs become fouled? Would they fire at all?
>
> I'm a new pilot and relatively ignorant of engine operations, so I'm curious
> to hear the answers.
Phillip
If you were unlucky enough, or foolish enough to fly into a volcanic
ash cloud, your engine would probably quit within minutes. That is if
the turbulence, or heat, or other potential trash like huge boulders
isn't in there to get you first!
The ash would quickly plug the air filter choking out the airflow. The
ash would most likely corrode your windscreen to an opaque as well as
take off paint from the leading edges. The engine may quit entirely or
just run weakly. there are reports of jet aircraft that sucked up ash
cloud and destroyed the engines from the abrasive pumice they
ingested. Many people to the east of St Helens had some expensive
repairs to their vehicles after all the ash had settled. It was a
couple of feet deep in many places as far away as 90-100 miles in the
Columbia Basin and Moses Lake area.
A friend of mine was crop dusting east of St Helens in the Palouse
area, a day after it exploded, when he said the ash entered the
cockpit of the spray plane and he couldn't even see the panel! Only
many thousands of hours of experience saved him from crashing.
Oddly enough I was flying around St Helens about two weeks before it
blew up. Got some pics of the snow melting around the top of the
mountain. After I saw the eruption, I had to shake my head that I
wasn't flying over it then!! I did a lot of crop dusting in the WA/OR
area and some of it was on the south slopes of St Helen.

Ol shy & Bashful

[Teacherjh]

>>
There are plenty of films of people driving around
in the ash cloud.
<<

They are likely driving at ten percent power.

Jose

--
(for Email, make the obvious changes in my address)

[C J Campbell]

"John Clear" > wrote in message
...
> In article >,
> Peter Duniho > wrote:
> >
> >No kidding? I'm shocked.
>
> I've never heard the less then a dozen people left, but one of
> those Discovery Channel type shows awhile back was on using DNA
> markers to trace how humans have moved around and interbred over
> the years. One of the things they found was that at one point,
> the human population was drastically reduced to ~10,000 people.

Don't take Peter too seriously. If you see him on the street and say, "Nice
day," he will reply, "Who are you, the weatherman?" :-)

[Rutger]

> > that reduced the worldwide human population to fewer than a
> > dozen individuals
>
> Never heard that one before. Fewer than 12 people remaining, around the
> entire globe you say? Yeah, right. I doubt any scientist with an actual
> clue believes that.

Well, there *is* a certain well-documented story, very widely known
around the world, about a group of only 8 people left remaining after
a planet-wide calamity wiped out the rest of the human population, but
you probably don't believe that one either.

[Peter Duniho]

"Rutger" > wrote in message
om...
> Well, there *is* a certain well-documented story, very widely known
> around the world, about a group of only 8 people left remaining after
> a planet-wide calamity wiped out the rest of the human population, but
> you probably don't believe that one either.

Nope, I don't. Anyone who takes that story literally just isn't using their
noodle.

By the way, you have a funny definition of "well documented". There are
many versions of that story, none of which agree with each other in any
significant detail.

[Paul Sengupta]

"Rutger" > wrote in message
om...
> > > that reduced the worldwide human population to fewer than a
> > > dozen individuals
> >
> > Never heard that one before. Fewer than 12 people remaining, around the
> > entire globe you say? Yeah, right. I doubt any scientist with an
actual
> > clue believes that.
>
> Well, there *is* a certain well-documented story, very widely known
> around the world, about a group of only 8 people left remaining after
> a planet-wide calamity wiped out the rest of the human population, but
> you probably don't believe that one either.

The Hitchhikers Guide To The Galaxy?

Paul

[dancingstar]

MLenoch wrote:
> I was in the St. Helens ash fallout in 1980. I was in a hanger in Wenachee WA
> repairing the landing gear of a Steen Skybolt. The ash got into everything.
> My car was inside the hanger with the doors & windows closed. The ash got
> inside anyway.
> In mid morning when the volcano blew, I heard the eruption. I wasn't near any
> radio/TV, thus I thought I heard a sonic boom from a passing fighter. A few
> hours later the ash came, preceeded by dark clouds like a midwestern fast
> moving cold front....little did I know.
> VL

Yep...I went down to Centralia (south of Olympia) and there was a few
inches of ash solidly covering the highways. They scooped most of it up
but it still remains to this day in huge piles along side of I-5 where
the Toutle river intersects.

The huge old growth fir trees that surrounded Mt St. Helens were knocked
down like toothpicks--it's quite the sight to see these monsters all
laying down pointing away from the mountain for 10 miles. They were so
impregnated with the silica-based ash that the logging companies
couldn't economically harvest them because the blades on their saws were
wearing out too fast.

Still, and as I mention in the newest thread on this subject below,
there are no notams or airmets out. I wonder why?

Antonio

[Markus Voget]

Corky Scott > wrote:

> On Fri, 01 Oct 2004 02:20:25 GMT, Philip Sondericker
> > wrote:
>
>>I was thinking about this recently, and I was trying to determine
>>exactly what the effects would be on a small plane flying into an ash
>>cloud.
>
> I recall reading a first hand experience of exactly what you are
> describing.

Hi Corky,

the story you related is in my memory as well. About ten years ago, I
used to read flying stories from a gopher server. This was called the
"rec.aviation archive". It had a collection of around 50 great stories,
among them the Mount St. Helens one. Unfortunately, I have been unable to
locate this information ever since. The closest I came was the following
old posting but the link in there does not work anymore:
http://groups.google.com/groups?selm=49g6o8%24qls%40Mercury.mcs.com
Does anybody know a new location of the mentioned site?

There were some other gems among the stories, too. I recall vividly a
visit to a Concorde cockpit and the famous Cessna hijack story (still
online today at http://www.prime-mover.org/Personal/travis.txt).


Greetings,
Markus

[Dan Thomas]

(SelwayKid) wrote in message >...
> Philip Sondericker > wrote in message >...
> > in article fT27d.3595$mS1.2578@fed1read05, BTIZ at
> > wrote on 9/30/04 7:00 PM:
> >
> > > that would be one heck of a thermal ride... if it weren't for the rocks...
> > > and "cough cough" the ash..
> > >
> > > BT
> >
> > I was thinking about this recently, and I was trying to determine exactly
> > what the effects would be on a small plane flying into an ash cloud. How
> > long would it take for the air filter to become completely clogged? And at
> > that point, assuming the plane had a carburetor, what would be the effect on
> > the engine? Would the plugs become fouled? Would they fire at all?
> >
> > I'm a new pilot and relatively ignorant of engine operations, so I'm curious
> > to hear the answers.
> Phillip
> If you were unlucky enough, or foolish enough to fly into a volcanic
> ash cloud, your engine would probably quit within minutes. That is if
> the turbulence, or heat, or other potential trash like huge boulders
> isn't in there to get you first!
> The ash would quickly plug the air filter choking out the airflow. The
> ash would most likely corrode your windscreen to an opaque as well as
> take off paint from the leading edges. The engine may quit entirely or
> just run weakly. there are reports of jet aircraft that sucked up ash
> cloud and destroyed the engines from the abrasive pumice they
> ingested. Many people to the east of St Helens had some expensive
> repairs to their vehicles after all the ash had settled. It was a
> couple of feet deep in many places as far away as 90-100 miles in the
> Columbia Basin and Moses Lake area.

Jet engines have almost no sliding parts exposed to incoming air.
Piston engines have many sliding parts, and ash or any other grit gets
between pistons and rings and cylinder walls and destroys them in
minutes. Grit will get past the piston and rings and foul the oil,
plugging the oil filter and causing the bypass to open, feeding gritty
oil to the pump and every bearing and gear. Alternator brushes and
vented mags would be in big trouble.
Tests on auto engines in the '80s by a piston ring manufacturer
found that a teaspoon of grit fed into a Chev 350 carb while running
near max power on a dyno would trash the engine in 5 minutes. No
compression, bearings gone, rattling madly. Anyone who deliberately
flies a lightplane into any ash cloud could be suspected of being
ignorant or insane.

> A friend of mine was crop dusting east of St Helens in the Palouse
> area, a day after it exploded, when he said the ash entered the
> cockpit of the spray plane and he couldn't even see the panel! Only
> many thousands of hours of experience saved him from crashing.

If the cockpit fills with ash, the central vacuum filter will plug
up quick, and there's no bypass to open. You'd lose all vacuum-powered
gyros; not the ideal situation in IMC.

Dan

[Markus Voget]

Markus Voget wrote:

> Corky Scott > wrote:
>
>> On Fri, 01 Oct 2004 02:20:25 GMT, Philip Sondericker
>> > wrote:
>>
>>>I was thinking about this recently, and I was trying to determine
>>>exactly what the effects would be on a small plane flying into an ash
>>>cloud.
>>
>> I recall reading a first hand experience of exactly what you are
>> describing.
>
> "rec.aviation archive". It had a collection of around 50 great
> stories, among them the Mount St. Helens one. [...]
> Does anybody know a new location of the mentioned site?

I found the stories again myself. Since they all seem to have originated
from a (nowadays unused) newsgroup they were still available on Google
Groups. If you go to
http://groups.google.com/groups?group=rec.aviation.stories
(ignore everything younger than 1999) you can still read them. The
volcano story is this one:
http://groups.google.com/groups?selm=1993Jul3.065701.27488%40peck.com


Greetings,
Markus