Jefferson City pilots took plane to maximum altitude

"Doug" wrote in message
ups.com...
What kind of engines did the aircraft on the Jefferson City flight
have? What kind of engines are on the Boeings that Bob flew?


Gas Turbine Engines.

Mike
MU-2

Mike,
Yes, Gas Turbine Engines. But what design, what manufacturer?
Different airplanes and different engines behave differently.

But think about it. Heat gets generated at lower altitude. There is a
thermal lag. That heat gets dissipated at higher altitude. If you are
climbing VERY fast, the incoming air is less dense, you can set up a
cycle where heat is accumulating faster than it can be transferred due
to the denser air creating more combustion. Sort of like having an
extra boost of turbo charging. With the slower airspeed in a climb, and
if the engine is operating close to the edge of it's heat dissipation
maximum, it COULD cause overheating. Anyway, you see my point, I hope.
(Even if it is wrong in this case).

But I will yield, as I have no supporting data. The supporting data
would be a climb limitation in the manufacturers flight manual. I don't
have it, but I am sure it exists. These internet arguments are never
won anyway. I'm not really interested in winning. Probably should have
worded my initial statement a little less concretely. I honestly
thought this was the cause. Apparently not, or at least not sure yet,
or not public yet. Whatever.

It's just my theory. Sorry about the two pilots dying. That is a tough
one for the families I am sure. Whatever the reason is, I am sure we
all want it found out so that other pilots and passengers can benefit
from the knowledge.

Airline travel is very safe, statistically, by the way. But you already
know that.

Sorry if I ruffled any feathers..

"Doug" wrote
But think about it. Heat gets generated at lower altitude. There is a
thermal lag. That heat gets dissipated at higher altitude. If you are
climbing VERY fast, the incoming air is less dense, you can set up a
cycle where heat is accumulating faster than it can be transferred due
to the denser air creating more combustion. Sort of like having an
extra boost of turbo charging. With the slower airspeed in a climb, and
if the engine is operating close to the edge of it's heat dissipation
maximum, it COULD cause overheating. Anyway, you see my point, I hope.
(Even if it is wrong in this case).

Young man...you don't have the foggiest idea about the operation
of aircraft jet engines.

Bob Moore

Bob,

This one certainly has me curious as to the cause. I've got very
limited experience in fanjets, but I've flown them at max operating
altitude and consider it a normal operation. In the turbojet 20-series
Lears we regularly went to FL450 in the 23 and 24B (usually after one
hour of flight) to get the fuel burns as low as possible when hauling
freight (plus, back then, there was nobody up that high and we always
got direct). In one version of the 25 we could go to FL510 although
even when very light, the climb rate going through 490 was so slow we
wondered whether we'd make 510 before time to start down (and, as you
know, you could see the curvature of the earth).

I did lose an engine at FL450 in a 24B when the captain moved the power
levers fairly quickly and an old fuel control unit couldn't handle it
at that altitude, flaming out the engine. We got a relight at 17,000
although, as I recall, the relight envelope was supposed to go to
25,000 (let's just say maintenance at that organization was not exactly
top notch - long out of business).

As a result, I'm curious as to what would cause both engines to go
quiet - the only common system is fuel, although I don't know the CRJ
systems at all and wonder whether there is/are any procedure(s) that
must be followed above a certain altitude regarding pumps or if the
company regularly flew so low that they didn't put in any additives
such as PRIST to prevent ice in the fuel. Have to contact a CRJ
captain friend of mine and see what she says. Also wondering why the
relight was unsuccessful...just doesn't make sense, jet engines are so
darn simple in operation - add fuel, ignite and go. Also wondering why
they couldn't make an airport from 410 in central Missouri.

The overheating comment on this thread is laughable. And I thought I'd
heard all of the nutty theories of aircraft accidents. Or maybe it was
some localized heavy gravity that shortened the glide range....

Your thoughts?

Warmest regards,
Rick

wrote
or if the company regularly flew so low that they didn't put
in any additives such as PRIST to prevent ice in the fuel.

That is what I suspect. In the Boeing jetliners, we didn't use
the additives (too expensive), but we did have fuel heaters on
the main filters to keep them from "waxing" over. A "one minute"
shot of hot bleed air every 30 minutes usually did the trick,
however I have had to reduce the cruise altitude and increase
the mach number to keep the tank boost pumps operating.

Bob Moore

"Bob Moore" wrote in message
. 122...
[...]
I'm putting my money on wrong fuel (freeze point) for the existing OAT.

I think the climb rate theory has been sufficiently disputed. However, I
find the thought that outside air temperature at FL410 might be an issue,
when (presumably) the airplane was being operated safely at a lower altitude
AT THE EXACT SAME TEMPERATURE, pretty silly too.

I don't know the exact altitude of the tropopause on the day of the
accident. But it was likely in the neighborhood of FL300 give or take a few
thousand feet. From the tropopause all the way up to FL410 (and higher),
the temperature would have been a relatively constant -57 C.

Sorry...that theory doesn't pass the sniff test any more than the "overtemp
due to climb" theory does. Not unless your theory is claiming that the
altitude the pilots climbed to was entirely irrelevant, and that the
accident would have happened regardless (I would find that to be a
reasonable inclusion in the theory, though it would beg the question as to
why other planes didn't have similar troubles that day, since the fuel
presumably sold to a wide variety of aircraft was apparently not suitable
for high-altitude flight).

Pete

"Doug" wrote in message
oups.com...
Mike,
Yes, Gas Turbine Engines. But what design, what manufacturer?
Different airplanes and different engines behave differently.

But think about it. Heat gets generated at lower altitude. There is a
thermal lag. That heat gets dissipated at higher altitude. If you are
climbing VERY fast, the incoming air is less dense, you can set up a
cycle where heat is accumulating faster than it can be transferred due
to the denser air creating more combustion. Sort of like having an
extra boost of turbo charging. With the slower airspeed in a climb, and
if the engine is operating close to the edge of it's heat dissipation
maximum, it COULD cause overheating. Anyway, you see my point, I hope.
(Even if it is wrong in this case).

But I will yield, as I have no supporting data. The supporting data
would be a climb limitation in the manufacturers flight manual. I don't
have it, but I am sure it exists. These internet arguments are never
won anyway. I'm not really interested in winning. Probably should have
worded my initial statement a little less concretely. I honestly
thought this was the cause. Apparently not, or at least not sure yet,
or not public yet. Whatever.

It's just my theory. Sorry about the two pilots dying. That is a tough
one for the families I am sure. Whatever the reason is, I am sure we
all want it found out so that other pilots and passengers can benefit
from the knowledge.

Airline travel is very safe, statistically, by the way. But you already
know that.

Sorry if I ruffled any feathers..


Frankly the overtemping due to climb theory is ridiculous and it doesn't
matter what gas turbine engines you are talking about. The fuel controllers
constantly sample inlet air temp and pressure along with the pressure at the
compressor discharge and trim the fuel flow to prevent the hot section
temperature from changing without power lever movement. More sophisticated
fuel controllers will allow the temp to rise with decreasing mass flow to
the temperature limit (or one of several limits) while keeping some other
parameter constant (like N1, fan rpm) then trim the fuel flow back to avoid
over temping the hot section. In any case it is fuel flow (ie mixture) that
determines temperature and the fuel controller is not going to be fooled by
climbing fast.

You are thinking about the problem like you would a piston engine.
Limiting turbine engine temperatures are analogous to EGT on a piston
engine, they are *not* analagous to CHT on a piston engine. It is a
function of fuel flow which is constantly monitored and adjusted by the fuel
controller...ie a *mixture* issue not a cooling issue.

Mike
MU-2

("Guy Elden Jr" wrote)
[snip]
Engine out issues aside, one thing that struck me about this accident
was the fact that these guys had so much altitude in which to glide to
a safe landing that I wonder if it was actually _too_ much altitude? I
don't know how far away the airport was that they finally decided upon
for the emergency landing attempt, but clearly they didn't succeed in
meeting their goal. Were they too complacent in thinking they'd be able
to restart the engines, given that they were nearly 8 miles up?


My thoughts exactly.

10:1 = 80 miles
15:1 = 120 miles

I wonder if they had x-length of runway as a landing requirement set in
their minds? Or, like that person in the Everglades, with a rough running
engine a month ago, heading for a patch of freeway - then diverting to an
airport that ATC advised, even though he wasn't sure if he could make it if
the engine quit. (It worked out for him)

I wonder if they had no ATC to advise them, would they have chosen to put it
down at a smaller (closer) 3,000-ft strip airport? Or, maybe they were ok
with the chosen field, but did some math wrong in their heads, and didn't
catch it until too late. Very sad.

Also, has 'no fuel' been ruled out? I might have missed that part.


Montblack

"Peter Duniho" wrote
I think the climb rate theory has been sufficiently disputed.
However, I find the thought that outside air temperature at FL410
might be an issue, when (presumably) the airplane was being operated
safely at a lower altitude AT THE EXACT SAME TEMPERATURE, pretty silly
too.

Maybe cold soaking...as often happened to me

Sorry...that theory doesn't pass the sniff test any more than the
"overtemp due to climb" theory does. Not unless your theory is
claiming that the altitude the pilots climbed to was entirely
irrelevant, and that the accident would have happened regardless (I
would find that to be a reasonable inclusion in the theory, though it
would beg the question as to why other planes didn't have similar
troubles that day, since the fuel presumably sold to a wide variety of
aircraft was apparently not suitable for high-altitude flight).

The predicted temp at cruise altitude determined the type of fuel
to be loaded...Jet A, Jet B, Kero A-1, or JP-4. I have had to
alter the cruise altitude due to the type of fuel that had been
previously loaded.

Bob Moore

"Bob Moore" wrote in message
. 122...
Maybe cold soaking...as often happened to me

That would not depend on the altitude however. In fact, if anything, "cold
soaking" would be more of a problem at a lower altitude, since there is more
thermodynamic mass to absorb heat from the airplane (and thus the fuel).

The predicted temp at cruise altitude determined the type of fuel
to be loaded...Jet A, Jet B, Kero A-1, or JP-4. I have had to
alter the cruise altitude due to the type of fuel that had been
previously loaded.

Thank you for that clarification. That does reinforce my understanding that
fuel temperature is unlikely to have been causal in this accident. That is,
there's no suggestion that the planned cruise altitude was low enough for a
"high temperature" fuel to have been loaded. Any cruise altitude even
moderately into the flight levels would require "low temperature" fuel (I
apologize for the generic terms...I don't know which types have what
temperature ratings).

Of course, without knowing the planned cruise altitude for certain, I can't
rule out the fuel theory. It could have been that the flight was originally
planned at a relatively low altitude. One thing your theory has going for
it is that it might explain the difficulty in restarting the engines, since
the fuel might not have had time to warm up enough during the glide,
especially assuming the temperatures would have remained too cold to do any
good for most of the glide anyway.

In any case, until such specifics are released, I still don't think that
speculation is likely to come up with much useful data. The NTSB should
be able to provide us with some real answers at some point, once they've had
enough time to sift through all of the facts.

Pete