leading edge flaps

On Mon, 12 Jan 2004 23:03:31 -0800, Mary Shafer
wrote:

Of course, the O'Hare DC-10 had a slat asymmetry, although that was an
asymmetric retraction of an extended slat. Subsequent simulator
studies showed that, even knowing the problem was asymmetric slats,
the airplane was too low to recover.

Mary

If we're talking about the same DC-10 that was lost at O'Hare about 20
years ago, the slat assymetry was caused by the engine and pylon
departing the wing, up and over and in the process taking a chunk of
leading edge with it.

The accident investigation and subsequent simulator trials
demonstrated fairly conclusively that the aircraft was recoverable,
however training to immediately pull up and reduce speed to Vmc was
incorrect. What was needed was the more high performance airplane
practice of "unload for control" in which you (counter-intuitively)
ease off the back pressure possibly all the way to zero G and let
airspeed build to a point where more G is available for the recovery.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
Smithsonian Institution Press
ISBN #1-58834-103-8

Ed Rasimus wrote:
Mary Shafer wrote:

Of course, the O'Hare DC-10 had a slat asymmetry, although that was an
asymmetric retraction of an extended slat. Subsequent simulator
studies showed that, even knowing the problem was asymmetric slats,
the airplane was too low to recover.

If we're talking about the same DC-10 that was lost at O'Hare about 20
years ago, the slat assymetry was caused by the engine and pylon
departing the wing, up and over and in the process taking a chunk of
leading edge with it.

The accident investigation and subsequent simulator trials
demonstrated fairly conclusively that the aircraft was recoverable,
however training to immediately pull up and reduce speed to Vmc was
incorrect. What was needed was the more high performance airplane
practice of "unload for control" in which you (counter-intuitively)
ease off the back pressure possibly all the way to zero G and let
airspeed build to a point where more G is available for the recovery.

What you're saying is true (e.g: the crippled DC-10 was indeed
recoverable in SIMULATOR flights) however;

1) During the actual event the stall warning system had been
rendered INOP due to the port engine departing the wing whereas
the stall warning system was functioning normally during the simulator
rides.

2) Although the pilots flying the simulator were able to recover
control after the roll began, these pilots were all aware of the
circumstances of the accident.

3) All participating pilots agreed that based on the accident
circumstances and lack of available warning systems, it was
not reasonable to expect the pilots of Flight 191 either to have
recognized the beginning of the roll as a stall or to recover
from the roll to which the Safety Board concurred.

In other words, unfortunately all those poor folks on American
Airlines Flight 191 back in '79 didn't stand a snowball's chance in
hell of walking away from that one!

Mike Marron wrote:
Ed Rasimus wrote:

Mary Shafer wrote:


Of course, the O'Hare DC-10 had a slat asymmetry, although that was an
asymmetric retraction of an extended slat. Subsequent simulator
studies showed that, even knowing the problem was asymmetric slats,
the airplane was too low to recover.


If we're talking about the same DC-10 that was lost at O'Hare about 20
years ago, the slat assymetry was caused by the engine and pylon
departing the wing, up and over and in the process taking a chunk of
leading edge with it.


The accident investigation and subsequent simulator trials
demonstrated fairly conclusively that the aircraft was recoverable,
however training to immediately pull up and reduce speed to Vmc was
incorrect. What was needed was the more high performance airplane
practice of "unload for control" in which you (counter-intuitively)
ease off the back pressure possibly all the way to zero G and let
airspeed build to a point where more G is available for the recovery.


What you're saying is true (e.g: the crippled DC-10 was indeed
recoverable in SIMULATOR flights) however;

1) During the actual event the stall warning system had been
rendered INOP due to the port engine departing the wing whereas
the stall warning system was functioning normally during the simulator
rides.

2) Although the pilots flying the simulator were able to recover
control after the roll began, these pilots were all aware of the
circumstances of the accident.

3) All participating pilots agreed that based on the accident
circumstances and lack of available warning systems, it was
not reasonable to expect the pilots of Flight 191 either to have
recognized the beginning of the roll as a stall or to recover
from the roll to which the Safety Board concurred.

In other words, unfortunately all those poor folks on American
Airlines Flight 191 back in '79 didn't stand a snowball's chance in
hell of walking away from that one!





But hey - they saved a *lot* of time changing the engines that way.

(Wonder if JT was involved in that idea?)

John

"John Mullen" wrote in message
...

snip
But hey - they saved a *lot* of time changing the engines that way.

(Wonder if JT was involved in that idea?)

The airline improvised their own way of completing a Douglas service
bulletin. It is a fact that the cause of the engine departure was some
dumbass mechanics ignoring Engineering.

The irony of your post is humorous, Mullen.

Ed Rasimus wrote:

On Mon, 12 Jan 2004 23:03:31 -0800, Mary Shafer
wrote:

Of course, the O'Hare DC-10 had a slat asymmetry, although that was an
asymmetric retraction of an extended slat. Subsequent simulator
studies showed that, even knowing the problem was asymmetric slats,
the airplane was too low to recover.

Mary

If we're talking about the same DC-10 that was lost at O'Hare about 20
years ago, the slat assymetry was caused by the engine and pylon
departing the wing, up and over and in the process taking a chunk of
leading edge with it.

The accident investigation and subsequent simulator trials
demonstrated fairly conclusively that the aircraft was recoverable,
however training to immediately pull up and reduce speed to Vmc was
incorrect.

But the thinking here is to gain maximum height and this will do
it in a normally configured a/c. That this one *wasn't* normally
configured couldn't be detected due to the 'slat asymmetry
warning' being unpowered because of failure of that busbar.

Had the slat warning worked then he 'wouldn't have pulled up to
Vmc'. So when the cojo followed instructions the port wing
stalled and took them in. They've since changed the dash one to
remove the requirement to climb at Vmc unless there's an urgent
need to.

This poor crew had everything against them, they lost the power
from that engine, they lost it's DC bus, they lost the slat plus
they lost the warning so even though the a/c was flown properly
they lost their lives because four major problems lined up
against them.

What was needed was the more high performance airplane
practice of "unload for control" in which you (counter-intuitively)
ease off the back pressure possibly all the way to zero G and let
airspeed build to a point where more G is available for the recovery.


But in the normal(?) case of a DC-10 engine fail there's lot's of
power from the other two so control isn't a problem and you'll
gain more height safety by climbing at Vmc...which was the
thinking then.

Apparently the chances of a wing engine failure plus an
asymmetric slat condition plus the left DC bus failure PLUS a
slat asym. warning failure was a pretty remote possibility.
--

-Gord.

wrote:

Ed Rasimus wrote:


On Mon, 12 Jan 2004 23:03:31 -0800, Mary Shafer
wrote:


Of course, the O'Hare DC-10 had a slat asymmetry, although that was an
asymmetric retraction of an extended slat. Subsequent simulator
studies showed that, even knowing the problem was asymmetric slats,
the airplane was too low to recover.

Mary

If we're talking about the same DC-10 that was lost at O'Hare about 20
years ago, the slat assymetry was caused by the engine and pylon
departing the wing, up and over and in the process taking a chunk of
leading edge with it.

The accident investigation and subsequent simulator trials
demonstrated fairly conclusively that the aircraft was recoverable,
however training to immediately pull up and reduce speed to Vmc was
incorrect.


But the thinking here is to gain maximum height and this will do
it in a normally configured a/c. That this one *wasn't* normally
configured couldn't be detected due to the 'slat asymmetry
warning' being unpowered because of failure of that busbar.

Had the slat warning worked then he 'wouldn't have pulled up to
Vmc'. So when the cojo followed instructions the port wing
stalled and took them in. They've since changed the dash one to
remove the requirement to climb at Vmc unless there's an urgent
need to.

This poor crew had everything against them, they lost the power
from that engine, they lost it's DC bus, they lost the slat plus
they lost the warning so even though the a/c was flown properly
they lost their lives because four major problems lined up
against them.


What was needed was the more high performance airplane
practice of "unload for control" in which you (counter-intuitively)
ease off the back pressure possibly all the way to zero G and let
airspeed build to a point where more G is available for the recovery.



But in the normal(?) case of a DC-10 engine fail there's lot's of
power from the other two so control isn't a problem and you'll
gain more height safety by climbing at Vmc...which was the
thinking then.

Apparently the chances of a wing engine failure plus an
asymmetric slat condition plus the left DC bus failure PLUS a
slat asym. warning failure was a pretty remote possibility.

Or at least was considered as such. In fact all were caused by the same
factor. The engine fell off.

John

John Mullen wrote:

wrote:


Apparently the chances of a wing engine failure plus an
asymmetric slat condition plus the left DC bus failure PLUS a
slat asym. warning failure was a pretty remote possibility.

Or at least was considered as such. In fact all were caused by the same
factor. The engine fell off.

John

Yes indeed, but then almost every aircraft accident is caused by
a string of problems, sometimes connected (as these were)
sometimes not.

Each by themselves usually no big sweat but taken together are
sometimes deadly. Consider this example, remove any one of the
series of four and they'd have recovered.
--

-Gord.

"Gord Beaman" wrote in message
...

snip
Apparently the chances of a wing engine failure plus an
asymmetric slat condition plus the left DC bus failure PLUS a
slat asym. warning failure was a pretty remote possibility.

Unless the Airline's mechanics ignore the Manufacturer's engineering, then
it is a certainty.

On Sun, 11 Jan 2004 06:05:28 -0600, "John Carrier"
wrote:

Slats are typically UN-powered devices on the leading edge that extend
simply by the reduced dynamic pressure against them as airspeed slows.
Example would be the leading edge extensions of the F-86 and F-100.

I wouldn't agree with "typically." Aero slats also extend when a certain
AOA is achieved ... the A-4 slats would extend at approximately 12 units AOA
(IIRC) and bringing them out symmetrically at higher airspeeds was not a
sure thing.

"How many angels (angles?) can dance on the head of a pin?" My use of
"typically" referred to the "un-powered", i.e. hydraulically or
electrically actuated/operated aspect. And, the examples (F-86 and
F-100) were aerodynamic, not mechanical. It, hopefully, recognized
that slats can be mechanically operated.

If they extend when airpressure is reduced as airspeed slows, then it
would be redundant to add "also when a certain AOA is achieved"
because that is the inevitable, inexorable, undeniable result of
slowing.

Gotta believe that the assymetric deployment even intermittently would
be exciting.

Really, the discussion of the wide range of wing-modifying devices
that have been employed over the years is amazing.



Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
Smithsonian Institution Press
ISBN #1-58834-103-8

If they extend when airpressure is reduced as airspeed slows, then it
would be redundant to add "also when a certain AOA is achieved"
because that is the inevitable, inexorable, undeniable result of
slowing.

I was thinking of maneuvering. The A-4 slat would extend up to around
350KIAS once the proper AOA was achieved ... hardly slow. I suspect the
various NA products behaved similarly.

R / John