Mt. Saint Helens

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.

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.

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.

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.

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.

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.

"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/aer...nic_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

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

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

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.