Sequence of events according to data from the CVR (cockpit voice recorder) and FDR (flight data recorder), as interpreted from the statement of Jim Hall from the NTSB

All times are given in PST (Pacific Standard Time) based on the destination.
The total time of the flight was 2 hours and 43 minutes.


1:38 ..... The plane lifted off the ground from Puerto Vallarta

1:41 ..... Approximately 3 minutes later the autopilot was engaged

1:54 ..... About 13 minutes later the autopilot was disengaged
(could they have had concerns at that point that it was not operating properly?)

3:47 ..... After flying manually for 1 hour and 53 minutes, the autopilot was again engaged

3:50 ..... The CVR was activated, and the pilots were heard discussing a problem with the stabilizer trim
(only 3 minutes after the autopilot had been engaged)

4:09 ..... The autopilot was again disengaged...

"Simultaneous with autopilot disengagement, the stabilizer trim moved to the apparent full nose-down trim position in about 6 seconds, and remained that way until the final upset."

4:10 ..... They contacted air traffic control and reported the problem...

"the initial transcript of the conversations between controllers and the plane indicated the cockpit crew struggled to control the MD-83 while making altitude and landing requests to controllers Monday afternoon." Source: CNN

A few minutes later they were given clearance to land at LAX, and they managed to control their descent for several minutes

4:20 ..... The plane went into an uncontrollable dive
(stabilizer may have broken at this point?)

4:21 ..... The plane hit the water

Observation: The stabilizer problem apparently became so severe during the period that the autopilot was engaged that the pilots felt compelled to report it to air traffic control.


Hypothesis:

I suspect that the DFGC (digital flight guidance computer) was sending erroneous signals to the stabilizer trim motor, causing it to behave erratically and arouse the concerns of the pilots, as they were heard discussing when the CVR was activated.

Argument:

Evidence seems to indicate that something caused the stabilizer gimbal nut to be shredded in a different manner than any type of normal operational motion would cause...

"Typical use should leave a residue of fine dust, not the long, curly strings found in the crashed Alaska Airlines plane."

The type of residue being found on other jets during recent inspection appears to be normal....

"Delta Air Lines grounded two of its planes Friday after employees discovered residue around their jackscrews that officials think is nothing more than normal wear, airline spokeswoman Peggy Estes said." Source: ABC

Now for a closer look at perhaps one of the most important pieces of evidence...

"Simultaneous with autopilot disengagement, the stabilizer trim moved to the apparent full nose-down trim position in about 6 seconds, and remained that way until the final upset."

Consider this as a possible explanation:

The stripped nut threads could be explained if the motor-driven jackscrew continued to apply force the stabilizer gimbal assembly after it had reached the end of its travel, with the jackscrew shredding the threads of the aluminum nut. The nut could have then became slightly cocked at an angle, and was effectively locked against the jackscrew by the torque being applied from the motor. When the autopilot was disengaged, the torque of the motor was reduced, allowing the stripped nut to loosen and the entire stabilizer assembly to slide along the jackscrew to the full nose down position within 6 seconds.

The nut could have been sufficiently stripped and loosened at that point that any attempt at moving the stabilizer by manual control simply slipped. Also, any grip on the stripped threads of the nut by the jackscrew would have been counteracted by the upward force being applied against the underside of the stabilizer during the rapid descent, and also the force of the elevator having been raised into nearly full nose-up position (most likely the attempt by the pilots to counteract the effect of the stabilizer in full nose-down position).




Summary points:

* Stabilizer problems became severe enough to report while the autopilot was engaged

* Significant event of stabilizer locking occurred simultaneously with disengaging of the autopilot

* Stripped nut damage much more severe than the normal wear and tear found on other planes


Conclusion:

The DFGC was sending faulty instructional signals to the auto pitch trim relays causing the stabilizer actuator motor to operate erratically.

Cause of faulty signals sent from DFGC: Microprocessor failure.

Cause of microprocessor failure: 90% likelihood of year 2000 non-compliance.


(Disclaimer: Any information other than that referenced by the provided links is conjecture on my part, as witnessed by my name at the bottom of this post. I have absolutely no experience, knowledge, or intelligence in the field of aviation, and this conclusion is based only on information that was available to me. (until presented with a more credible explanation, this is TTAIKI...the truth as I know it :-) Respectful, constructive criticism is welcome, but no experience or knowledge of any kind is required to make comments.)

-- Hawk (flyin@high.again), February 14, 2000

Answers

Hawk;

It is an interesting idea you propose, I contiunue to follow your conjecture. I do work with a lot of robots and jack screws, they fail from time to time and it can be due to many causes. Usually it is bad data from the shaft encoder that causes them to "hunt" (roam back and forth around the set point). I have always traced this problem to a broken wire, I do not know any servo loops in my employ (currently about 15) that are date sensitive in any way. But if you can find a link that shows a chip that was sensitive, more power to you!

At this point, I need more data to make an informed opinion.

-- Helium (HeliumAvid@yahoo.com), February 14, 2000.

Hawk,

So the statement about "microprocessor failure" and the reason for a microprocessor failure being "90% likelihood of Year 2000 non-compliance" are your words and not Chairman Hall's? What are your qualifications to make any such conclusions?

What strikes me from Hall's report is the sentence "the final descent from 17900 feet lasted just over a minute". My God, what the people on that flight must have endured in that minute.

-- (nemesis@awol.com), February 14, 2000.

Thanks Helium, that is good to know. I am speculating that the malfunction could possibly be originating within the DFGC, which does have a clock, and calculations might be performed to drive the motor at a predetermined rate, for example 1 degree per second.

-- Hawk (flyin@high.again), February 14, 2000.

"What are your qualifications to make any such conclusions?"

As I stated in the disclaimer, NONE. I am a complete and utter moron, so future posters don't even bother asking. (see I don't mind calling myself that, I just don't like being misunderstood :-) I am only doing this for fun. If someone checks it out and it saves lives I will be happy, but I'm not counting on it!

-- Hawk (flyin@high.again), February 14, 2000.

"My God, what the people on that flight must have endured in that minute."

Yes, very horrifying indeed. The plane was in an inverted corkscrew at an 80 degree angle of descent. The g-forces probably ripped most passengers out of their seats, and they were being tossed from wall to wall like ragdolls. Most were probably unconcious or dead before they hit the water.

-- Hawk (flyin@high.again), February 14, 2000.

Hawk,

It all started with a trim tab problem... and went from there.

You will never be able to Prove Y2k, or embedded chip problems to anyone... that's a fact of life... the laws/agreements for insurance companies won't allow it...

That said.... I think you're on too something..... kindda like oil :-)

-- Casper (c@no.yr), February 14, 2000.

HAWK It makes a lot of sense when you define the evidence of normal wear and stress lathings(long, curly strings of metal)...there must have been similar materials at the other sites of crash lands? ...or is there anything to find yet? I'm a moron too... I just go by gut feeling about things and what seems to be logical... but to me, there seems to be a lot of oil refinery explosions and disruptions, chemical plant fires, explosions and disruptions, sewage spills, poisonous spills, major water line breaks and explosions, corruption of computer mainframe data, to warrant a belief that government lied and we need to look closer at the possibility that y2k may be more serious than we are lead to believe by our undistinguished leaders. I know I am just a moron, but can you give your opinion about what we should expect in the next couple of weeks regarding air-travel? I was a moron in Vietnam too, I never had any evidence to prove that we could expect trouble and I never had a degree to give me the edge, so I just got alone with my gut instincts... faired alright then...I can trust a man who isn't over-trained and has street wisdom so-to- say! BRyan

-- S BRyan G III (sbrg3@juno.com), February 14, 2000.

so what do you think made the loud noises that have been mentioned? aren't we looking at the egypt air flight as the same possible scenario? remember something made loud noises, whatever happened appeared to have happened in the tail, i think the plane behaved in a similar manner as the alaska plane? wonder if they found the jackscrew on that plane?

-- tt (cuddluppy@aol.com), February 14, 2000.

"I am a complete and utter moron", maybe TB2000 ccould copyright this statement and use it as their new slogan.

-- Butt Nugget (catsbutt@umailme.com), February 14, 2000.

Perhaps YOU should adopt the moron slogan, Butt Barbecue.

-- haha (haha@haha.com), February 14, 2000.

Interesting analysis Hawk.

Here's a question to ponder. The newspaper was reporting yesterday that similar "flaws" are being found on the jackscrews of other same model planes. Are the "flaws" inherent in the jackscrew, or are they being created by the sort of faulty signal you describe? And, how to prove one way or the other?

-- mommacarestx (nospam@thanks.com), February 14, 2000.

Hawk, thanks for your continued efforts to shed some light on the reasons for this tradgedy. As a previous poster indicated, TPTB will NEVER admit to a y2k problem, but I am sure that when this is finally adjudicated the truth will be at hand.

Ray

-- Ray (ray@totacc.com), February 14, 2000.

S BRyan, I don't expect any more serious crashes in the near future, as the maintenance crews will be keeping an eye out for the telltale signs. I think that pilots may avoid using the autopilot as much as possible, and will be alert for anything unusual, hopefully being able to land safely as so many have. This one may have been a fluke, but I think we will be seeing an increase in computer-related flight problems.

tt, I think the first loud noise was the sound of the nut breaking loose and the stabilizer being forced up to the full nose-down position by upward air pressure. The second noise might have been a portion of the stabilzer snapping off from the extreme stress.

mommacrest, good questions, I don't know. As time goes by, I suppose a pattern may develop, helping us to nail down the exact cause. I think checking the jackscrews was a good start, but that was not the cause of the problem.

-- Hawk (flyin@high.again), February 14, 2000.

---I have a question on flight data voice recorders, aren't they on a 30 minute time span, then they re-record over the same place? just a question, no conjencture, hawk and the pollys are all doing excellent,good jobs here trying to sort this out long distance. I like it.

Now commentary in general: I am ever so slightly leaning towards y2k related problems in general with all these accidents, glitches, booms, smashes, bursts, explosions, leaks, spills, shutdowns, unscheduled maintenances, "no it isn't y2k but we need an investigation(s)", et cetera, et cetera for two reasons. "It" appears to be following the "most likely scenario" by the brains I RESPECT-not the foul troll hacker brains-and by the sheer volume of "glitches". But, like as said, the federal law allows lying, that's what it boiled down to, if this wasn't of supreme importance to all these companies then they wouldn't have lobbied long and hard for the "cool to lie" law-which leads inescapably to "there's a LOT of y2k problems out there or perceived or whatnot", and also that "they" anticipated the long haul of strange, re-occuring, hidden, new, who-knows-what type problems well into the year, not just jan first.

As the public media won't even mention the phrase "y2k" anymore, it really is up to a very very tiny few of concerned and dedicated people on the web to keep up the good work. Not that there aren't simply millions of people who have been "bitten" by any of these glitches so far who aren't smelling rats, it's just that we've been innundated with herds of rats to smell over the past few decades, and especially the last decade. I know I trust NOTHING any big corporation or big government says anymore,NOTHING, and that's THEIR fault, not mine, and both of those entities have ample money to employ paid disinformation propoganda agents, "public relations", plenty of money for that, and the "buzzwords" of any sort of technical-speak may be learned, coached or provided, and technogeeks of any profession may be bought off as well.

The stakes are huge in this, if this or any other major problem is revealed to be y2k in public it would be DEVASTATING, so, even if true, the liars will cover their butts, like they always do. The bottom line is that they have an historical track records of lying, over and over and over again, and trot out "experts" and "scientists" who are proven to be paid off shill liars years later. DDT,thalidomide,agent orange, gulf war syndrome, nuclear on-purpose-exposure on unknowing victims are just a few examples of corporate and governmental liars. The ones who tell the truth,sorry,really I am,but you're known by the "company you keep". Hang out and work with and for liars, you get associated weith them. You joined their gang, or it turned into a gang around you and you didn't leave, the money is more important than the morals and ethicws to you and that's YOUR choice, NOT mine. I could care less about your pension or job. I CARE about people getting hurt because of corporate and governmental malfeasance and collusion. I care about people getting ripped off, I care about people losing court cases because the billion dollar company has the money and resources to bankrupt the plaintiff and pay off the judge, I care about the people hurt by big bro and his controlled courts and bought off judges and prosecutors, big bro who is immune from any oversight or checks. I care about legitimate companies put out of business by big bro in the name of social reengineering, that's who I care about, not some shills' car payment or vacation to aruba.

I may be quoteth-->"Byte me, goons"<---I'm hip to you,goons, and millions more people are getting hip every year. That's why you want to control the web, isn't it goons, isn't it? And I know you are reading this, too, so I repeat "byte me".

-- zog (zzoggy@yahoo.com), February 14, 2000.

So very true, zog. I wouldn't be suprised if many airlines are recommending to their pilots to not use the automatic pilot until this thing is sorted out which is probably a good idea, but they still need to find the cause of the problem as quickly as possible. I hope they aren't planning on taking the usual 2 or 3 years to figure this one out.

-- Hawk (flyin@high.again), February 14, 2000.

This just in...

Alaska Airlines considered new nut for crash plane

Updated 12:49 AM ET February 14, 2000

By Tim Dobbyn

WASHINGTON (Reuters) - Safety investigators Sunday said the Alaska Airlinesplane that crashed two weeks ago had been considered in 1997 for replacement of a key tail part but maintenance workers changed their mind after further tests.

The National Transportation Safety Board said a review of the MD-83's maintenance records showed an initial test of the fit between the screw and nut that controls the horizontal stabilizer was at the "maximum allowable end play limit."

A statement by the safety board said the records showed the initial plan was to replace the gimbal nut but the plan was reevaluated and the wear limit was checked six more times and the results came within specified tolerances.

The pilots of Alaska Airlines Flight 261 complained of difficulties controlling the horizontal stabilizer before the plane plunged into the Pacific Ocean near Los Angeles Jan. 31, killing all 88 people on board.

Examination of the wreckage showed severe damage to the gimbal nut, whose threads were found wrapped around the jackscrew.

Those findings and damage seen in other Alaska Airlines planes prompted the Federal Aviation Administration to order a nationwide check of 1,100 planes over the last three days that has revealed 21 reports of problems with the stabilizer mechanism.

The stabilizer maintains the plane's attitude in steady flight, climbing or descending. Flight 261's stabilizer went full nose-down some 12 minutes before the crash.

The FAA said late Sunday the types of problems seen in the checks ranged from grit to metal filings in the jackscrew lubricant. Boeing has said normal wear should just produce a powdery residue in the grease.

The safety board said it was continuing to evaluate this latest information on Flight 261 and further search the maintenance records since the plane's manufacture and delivery to Alaska Airlines in 1992.

"No determination has been made as to whether this information has any bearing on the accident," it said.

Earlier on Sunday, FAA Administrator Jane Garevey said her agency and the safety board were looking very carefully at Alaska Airlines' maintenance records and procedures.

The airlines has faced investigations by a grand jury and the FAA into maintenance and repair records regarding its fleet of MD-80 airliners. It has maintained it saw no connection between investigations of its aircraft maintenance policies and the crash.

The carrier has said it referred eight of its 34 MD-80 planes for further evaluation by officials after examining the jackscrew assembly.

"Obviously in light of the accident we're taking a very, very, careful look with the NTSB at the maintenance records, at the procedures that they (Alaska Airlines) have in place," said FAA Administrator Jane Garvey on the Cable News Network's Late Edition program Sunday.

The FAA's 72-hour inspection order covered U.S.-registered MD-80, MD-90, DC-9 and Boeing 717 aircraft, a family of planes that trace their basic design back to the DC-9. All airlines should be done Monday.

Carriers were given 30 days for the more precise test of wear between the jackscrew and gimbal nut that Flight 261 underwent during a heavy maintenance check in September of 1997 at the airline's facility in Oakland, Calif.

The results of the additional tests that showed the fit was still acceptable were signed off by an Alaska Airlines maintenance inspector, the safety board said.

The FAA Sunday did not give an airline-by-airline breakdown of its latest count of problems uncovered to date.

Northwest Airlines said Sunday it had replaced the jackscrews on three of its 172 DC-9s. "We're all done now," said Northwest spokesman Jon Austin. FAA had listed Northwest late Saturday with just one finding of significance.

AMR Corp.'s American Airlines insisted Sunday it had found nothing in its fleet so far despite FAA listing it Saturday as having reported one problem.

"We have inspected 238 of 284 and we have found no problems and we will be completed by this evening," said American spokeswoman Martha Pantin.

Delta Air Lines , which had identified four aircraft for greater scrutiny, said it had completed inspections on 125 of its 136 MD-88 and MD-90 fleet.

At other carriers, FAA had listed Airtran with two aircraft and one each at Continental, TWA and Hawaiian Air.

-- FWIW (@ .), February 14, 2000.

Mr. Hawk, Im envious of your vast amount of free time to form the speculations that are brought forth here on this forum. You are apparently a man of independent wealth, or is it because your folks are letting you stay at the trailer at no cost? In any case I fear you will be disappointed to discover that Y2K and computers had absolutely nothing to do with the demise of Alaska Airlines Flight 261. Unlike yourself I am an expert in these matters. Rather than bore you with my credentials I will simply tell you what went wrong and you will soon know this to be true. Please, save your breath as you have already demonstrated enough of your ignorance to fill volumes.

There was a catastrophic failure of the jackscrew/Gimble nut assembly that resulted in a complete separation or stripping out if you wish. This allowed the horizontal stabilizer to somewhat free float and left the aircraft without any control.

As is now being reported, this same aircraft failed an inspection of these components in 1997 but was given a green light with further testing. This, and not your foolish Y2K fantasies, will prove to be the cause of this tragedy and result in some serious repercussions for Alaska Airlines.

-- Ra (tion@l.1), February 14, 2000.

Spell check on...Gimbal.

-- Ra (tion@l.1), February 14, 2000.

Oh GOODY!

Just what we need now! A self professed expert!

My Dear Mr. Ra,

It is indeed funny for you to choose the name of the Egyptian sun God. I guess it means that you are going to take pity on us poor folks, and shed "some light" on the subject (according to Ra).

While I find your retoric to be condesending, when you speculate on how another person should spend their time..Perhaps you should indeed try and render a verdict from on high (according to your estimations, either personally arrived at, or what you have been given to pass out as the PC line).

Untill then, I'll call you by your familuar name "TROLL". And reserve any bowing down to your edicts "from on High"! Untill you "Part The Waters (or else walk on them)".

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 14, 2000.

Hawk, Interesting argument. I, too, want to know about other planes that have showed jackscrew stress. As for those who think attack the man and not the argument is a valid manner of debate, it isn't.

-- Mara (MaraWayne@aol.com), February 14, 2000.

Darn folks...

When I wrote the "T" name out...I was worried that I would call up THE REAL TROLL ! And apparently I did. Well! There goes the neighborhood (the thread) again. Won't be any further information coming from this one. The "burger flipping" expert has arrived. And Ra you should ask this "enlightened one"( and if you do't believe he is-just ask him) where he gets his free time from. I suspect he lives in the RV out back, not the Hawk.

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~Shake~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.fee), February 14, 2000.

Ra:

One more thing. Y2k Pro has been harping on this theme for months now. I wouldn't take the observations of a no-life loser like him/her/it too seriously, like I don't take anyone's on this board. Most of it is just in the interest of discussion, something that pea- brain Y2k Pro can't understand.

-- Zq (Z@Z.com), February 14, 2000.

FAA may speed up precision test of MD-80 tails

By Tim Dobbyn

WASHINGTON, Feb 14 (Reuters) - Federal aviation officials on Monday were considering speeding up a precise nationwide test of the tail mechanism in MD-80 and related airliners after viewing maintenance records from the Alaska Airlines plane that crashed two weeks ago.

U.S. airlines on Monday were wrapping up a three-day visual inspection of the jackscrew and nut that controls the horizontal stabilizer but had been given 30 days for a precise measurement of the amount of wear between the two parts.

The National Transportation Safety Board on Sunday said Alaska Airlines back in 1997 had found the nut on the accident plane to be ready for replacement but then reversed itself after additional tests showed the wear was within limits.

The U.S. Federal Aviation Administration that ordered the inspections last week said it was now wondering if the test for the amount of "play" between the two parts should be done sooner.

"We are considering that now," said FAA spokesman Paul Takemoto.

The pilots of Alaska Airlines Flight 261 complained of difficulties controlling the horizontal stabilizer in their MD-83 before the plane plunged into the Pacific Ocean near Los Angeles Jan. 31, killing all 88 people on board.

Examination of the wreckage showed severe damage to the gimbal nut, whose threads were found wrapped around the jackscrew.

The stabilizer maintains the plane's attitude in steady flight, climbing or descending. Flight 261's stabilizer went full nose-down some 12 minutes before the crash.

FAA's order covered MD-80, MD-90, DC-9 and Boeing 717 aircraft, a family of planes that trace their basic design back to the DC-9.

With the visual inspection of 1,027 U.S.-registered planes almost complete, the FAA said on Monday it had 21 reports of problems ranging from metallic grit in the jackscrew grease to metal slivers coming off the gimbal nut.

FAA said the tally of problem planes by airline was as follows: Alaska Airlines with eight, Delta Air Lines with four, Airtran with three, Hawaiian Air with two, followed by one each at AMR Corp.'s American Airlines, Continental Airlines , Northwest Airlines and TWA .

The safety board said on Sunday it was continuing to evaluate the latest information on Flight 261 and further search the records since the plane's 1992 manufacture for all maintenance associated with the stabilizer.

Safety investigators on Sunday said the Alaska Airlines plane that crashed two weeks ago had been considered in 1997 for replacement of a key tail part but maintenance workers changed their mind after further tests.

The National Transportation Safety Board said a review of the MD-83's maintenance records showed an initial test of the fit between the screw and nut that controls the horizontal stabilizer was at the "maximum allowable end play limit."

A statement by the safety board said the records showed the initial plan was to replace the gimbal nut but the plan was reevaluated and the wear limit was checked six more times and the results came within specified tolerances.

========================================= End

Ray

-- Ray (ray@totacc.com), February 14, 2000.

Thanks HAWK, so you believe that the government will prompt aviators, or aviators will do it on their own judgement to not use the autopilot? Do you think the government will actually admit that there is something wrong with the electronic or will they stick with mechanical failure story and give the O.K. to retract the grounding of the MD-80's? What about the other countries, are they taking measures to find out the truth also...since many of these aircraft are in world wide use? BRyan

-- SB Ryan G III (sbrg3@juno.com), February 14, 2000.

Ra says...

"There was a catastrophic failure of the jackscrew/Gimble nut assembly that resulted in a complete separation or stripping out if you wish. This allowed the horizontal stabilizer to somewhat free float and left the aircraft without any control."

Gee that sounds an awful lot like you stole my theory, except you left out one part. Is there a CAUSE for this "catastrophic failure", or is that something that "just happens" ???

I would suggest that with what little free time you have you should try using your brain for a change.

-- Hawk (flyin@high.again), February 14, 2000.

Hawk,

Why are you so obliged to make this a y2k computer induced failure? Things break mechaniclly; catastrophically. It happens for many reasons: fatigue fractures, corrosion, metallurical faults, overloads, poor design (several space catastrophes come mind--the O rings in the space shuttle, the pure oxygen environment in Gus Grissom's space capsule, the Apollo 13 explosion. Bridges fail, dams burst, vehicle brakes fail, ad nauseum. It happens, don't force it into a y2k mold.

-- (nemesis@awol.com), February 14, 2000.

Try as I may the urge to respond on this thread is too compelling to ignore. Over and over, we are bombarded with the delusional nightmares that leak out of the pea-brain known as Hawk. Sir, you have the same right as anyone else to speak your mind but you should expect to be ridiculed for your outrageous speculations. Instead, you let your foul mouth take over instead of reasonably debating your detractors. I would hope that most people would see through the support that shills like Shakey provide and demand some modicum of credibility from your postings. After all, isnt this how the Y2K situation got so far out of reality, input from morons like you who have no factual foundations for your BS. Still, I enjoy your words when you remain civil and wish for your full recovery.

-- Sifting (through@the.rubble), February 14, 2000.

HAWK, The Denial New Media reported today that FAA deadline today to complete all test of MD-80 aircraft ...what does this mean exacly... that there is no electronic probes but just mechanical check ups? Seem silly to be so narrow-minded as to only check for one probable cause...but because there are so many narrow-minded lookie- loos...maybe we should expect a further trend of aircraft problems. It is a mental disorder I think that would cause someone to deny the possibility when it involves so many lives on a daily basis...I understand why you are not investigating the mechanical end as much as the y2k end...it seems that there are already too many already investigating the mechanics of the problem...wish we could get to the bottom of this... almost frustrating to not see everything possible cause seriously put forth and investigated...

-- SB Ryan G III (sbrg3@juno.com), February 14, 2000.

Sifting,

Mr. Ra called me ignorant and I told him he should use his brain. I don't see anything foul mouthed about that. I don't get mad, I get even. I guess you're just another troll.

Since you haven't added anything relevant to the subject I'd like to request of the sysops that they delete your "contributions."

-- Hawk (flyin@high.again), February 14, 2000.

Hawk, my comments regarding your foul language were not directed at anything you said on this particular thread so dont waste your time trying to deflect responsibility. You have a long and documented history on this forum, both as A and Hawk. Personally, I am not offended by your wordsheard much worse from real people. And I seriously doubt that the overworked forum sysops really care what you think or demand. You have the right to speculate and I have the right to oppose your foolishness. I can recall on occasion when I agreed with your position on this subject or that. But Im tired of the constant need for you to label everything with the Y2K problem header. You sound like a fool more often than not and your few supporters just confirm these suspicions. These of course are my personal opinions and like yours, open for debate. I have to agree with those who report that the jackscrew assembly had a wear problem. How this could be a date driven computer related failure is beyond reasonable thinking. But please, dont let that stop you.

-- Sifting (through@the.rubble), February 14, 2000.

"You have the right to speculate and I have the right to oppose your foolishness."

I agree.

"But Im tired of the constant need for you to label everything with the Y2K problem header."

Too damn bad. I'm tired of the constant need for you to contradict any possibilty of Y2K.

"But please, dont let that stop you."

Believe me I won't, and I sure as hell don't need your permission.

-- Hawk (flyin@high.again), February 14, 2000.

"Try as I may the urge to respond on this thread is too compelling to ignore."

Of course, that's because you're a worthless troll with no life of your own. Please try a little harder, would you?

"Over and over, we are bombarded with the delusional nightmares that leak out of the pea-brain known as Hawk."

I like delusional nightmares, they're fun. But I especially enjoy it because I know it pisses off intolerant pigs like yourself.

"Instead, you let your foul mouth take over instead of reasonably debating your detractors."

Don't kid yourself, calling me a pea-brain is no less offensive than calling me an asshole. They are just different words, but both offensive. Your intent is obvious, even though you think you can get away with it by using childish words. My foul words are just a response to assholes like you who are obviously asking for it!

Have a nice day. :-)

-- Hawk (flyin@high.again), February 14, 2000.

BRyan,

You have some excellent points and questions, thanks. My feeling is that the focus in the media will continue to be on the gimbal nut because the people are stupid enough to buy it. Put some new nuts on the ones that show some wear and tear, yeah that'll fix it. I believe the NTSB is trying to determine what caused the nut to be stripped out, and they of course are considering the autopilot and actuator mechanism, but we will never hear about that... too risky. I don't thing they will be grounded any longer... too costly. Smart pilots will probably suspect the autopilot and avoid using it. Interesting that these pilots chose to turn it off for almost 2 hours after the first 13 minutes, during the easiest part of the flight when it would normally be used. If the NTSB does discover some problems with the autopilot, these will be quietly repaired one by one without reducing the normal flight schedules, and no mention in the news.

nemesis, (That means "enemy" doesn't it? Hmmm, nice name)

"Things break mechaniclly; catastrophically. It happens for many reasons: fatigue fractures, corrosion, metallurical faults, overloads, poor design"

And which of these would explain the stripped gimbal nut?

-- Hawk (flyin@high.again), February 14, 2000.

My dear Mr. Hawk,

Sir it would seem that the "experts" Ra, Y2K Pro, and now the llustrious Mr. Sifting are not able to make a mental jump in their minds. But they sure do in their opinions it would seem.

I do hope you do not mind me trying to give one possible embedded systems causitive to the stripped Gimal niut.

In the past, while trying to regulate the "travel" functions on motorized valves, which uses a Jack Screw to close the valve gate. We had to be very careful with either the PLC or it's subset controls; or sometimes both. That we didn't cause the motor driving the jack screw, to continue to close the valve (after the valve's gate had physically closed).

The "worm" gear of a jack screw receives a fraction of the wear and tear that a gimbal nut's threads do over their respective life span. And thereforth, if for no other reason, are weaker than the threads of the jack screw.

But in any case...If you jam a gimal nut, and continue to "drive" the jack screw! You will invariably strip threads! And the threads stripped! Will be the nut's threads! So I would search out that segiment of the emedded systems which governs the jack screw's travel FIRST! Then trouble shoot from that point. And I would at the same time check for what passes in avionics as a limit switch at both ends of the jack screw's travel to see if one of them had failed..

Sifting, go sift somewhere that you can find something you might understand. It is readily apparent that the Hawk can bring forth any amount of information, with diagrams; even photographs...And you, Y2K Pro, and the illumious Ra still cannot find the directions on the heel...Shill indeed! Sonny you couldn't/wouldn't be allowed to carry a tool pouch, much less a set of prints..Now back to Trouble Shooting 101 for you.....

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 14, 2000.

Looks like we're making progress here. Last week it was "definitely Y2k related." Now we've progressed to "90% likelihood of year 2000 non-compliance."

At this rate, Hawk should get it right sometime in April, realizing that Y2k is not a factor in the AS261 tragedy.

In the question and one of his first answers, Hawk makes some statements about himself. I promised to stop the name-calling, so Hawk --- good job!!!!

-- Mikey2k (mikey2k@he.wont.eat.it), February 14, 2000.

Thanks Shakey, you and I are thinking along the same lines. The limit switch is definitely something that should be checked out. Is this equivalent to a kill switch, or does it just send a sort of temporary "pause" signal to the actuator mechanism, like a VCR when you pause the tape?

Based on the timeline of the data from the FDR, it is difficult for me to exclude the possibility that the autopilot had something to do with it, as it was related to the timing of the key events. It's as though the signals being sent through the auto pitch trim relays were corrupted, perhaps causing the motor to perform erratically, and perhaps continue running when it should have stopped ( I know, sounds funny, like the computer in 2001 taking over the ship..lol!) I can't imagine how the NTSB can explain this without finding some fault in the electronic circuits at the very least.

-- Hawk (flyin@high.again), February 14, 2000.

Hawk,

This is a very interesting thread. Thank you.

Hawk, this is not a technical question, but have you ever read any books by Richard Bach? Just curious since you seem to enjoy planes from what I have read on your posts. I have a lot of friends who are pilots and they enjoy his books. My dad loves planes too, he's former Air Force, so I bought him one of Richard's books entitled "A Gift of Wings" for Christmas one year. He really liked it.

-- Dee (T1Colt556@aol.com), February 15, 2000.

A limit switch is contained within the actuator itself, and is activated mechanically. No microprocessors, non-compliant or not, involved.

I consider a malfunctioning or misadjusted limit switch as one of the suspects in this tragedy. I imagine the NTSB is looking at this issue. But I wonder if this is a real possibility, given the distance the threads appear to have travelled along the jackscrew in the photo. Perhaps a mechanical engineer could comment on this.

-- Mikey2k (mikey2k@he.wont.eat.it), February 15, 2000.

OK, I give up. Now that two pedantic experts such as Hawk and Shakey are on the case, why should I, the NSTB, or anyone else waste another second analyzing the cause of the AA#261 crash. The only remaining mystery is why you two decided to exclude Moe from this project.

Oh Hawk, my guess is that Mr. Sifting wanted to say what a dipshit pea-brained asshole you are. There, you feel better now?

-- Ra (tion@al.1), February 15, 2000.

And the other 4-5 MD-80 series that made emergency landings within 7- 10 days of Flight 261??? Do they fit into the analysis in any way? That can't be a statistical norm for the "safest airplane ever built" can it? Of course it could be a coincidence -- they do happen.

Nevertheless, ordinarily, one would be justified in considering a common causation for similar events happening unexpectedly to the same model equipment at the same time -- certainly if there are any date-sensitive electronics like embeddeds. So why given the near- simultaneous emergencies on board 4-5 aircraft of the same type, is it in any war irrational to consider a common cause for the malfunctioning equipment -- like misfiring autopilot electronics?

>"<

-- Squirrel Hunter (nuts@upina.cellrelaytower), February 15, 2000.

Thanks Dee! I have heard of Richard Bach's books, but haven't yet read one. Since I've always enjoyed other books about flying, I appreciate the recommendation, and will look for them at B. Daltons. My dad is also a pilot with twin-engine and instrument ratings, and a retired air traffic controller. He gets to ride free as an observer whenever he wants to travel because of his FAA experience. He's been around planes since he was a Navy Air Force pilot as a young man, and I've been priveleged to enjoy many box seats at air show since I was a kid. Even got to ride in the plane as my dad did a flyby in a Cessna 210 twin engine in front of the crowd at an airshow. We also rode along in an old Ford tri-motor flyby. I've always loved planes. Thanks :-)

-- Hawk (flyin@high.again), February 15, 2000.

And good evening to you Mikey,

I would rather think that the limit switch would "talk" to the D.C. motor's control (be it PLC/POM/PROM) or what is used for this purpose.

In any case, there is a controller, which "tells" the D.C. motor when to run, when to reverse jack screw travel...And when to stop it. And it is there you will find embedded chips (I will not believe that they have a tiny little elf sitting in the flight control with his hot little hands on a series of single pole toggle switches). The is a programmable logic controller some where in the mix, between the pilot'/ co-pilot's controls and the D.C. motor at the rear of the tail assembly. Just as there is somthing which must do the job of varying the motor's speed....

A chip failure can be caused by many things, inluding just plain old component failure! I have smoke tested a few of them in my day..And as far back as 78' we knew about what we called the infinity dates in the chips also.

When looking at the photograph of the stabilizer, it appears that the D.C. motor is located at the top. Which would correspond roughly as the "closed" position on a motorized valve. If so, then if it where chip failure...The valve would close; it's motortrying toclose it,still running! By extrapalation...The jack screw would travel up ward (towards it's closed position)...Now let's see...If the forward section of the stabalizer is pushed up ward. That would put the plane's forward attitude in what position? The down posiion?

But this is all pure conjecture isn't it! I mean, I am just an old shirt tailed electrican, with a perchance at control trouble shooting.Have a nice evening Mikey.

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunke@forty.feet), February 15, 2000.

Mikey,

When threads strip-out, they strip in a spiral around the threads that stripped them.... you can't make anything out of the pictures they show on the tube, it would look the same if the Jackscrew over-ran the stop, or if the elavator over powered the strenth of the gimble-nut and caused it to stip.... I still can't see anything that would cause this when it STARTED as a problem with the stabiliser TRIM TABS !!!!!!

-- Casper (c@no.yr), February 15, 2000.

Ooops! Sorry, meant to say Cessna 310 (twin engine). He sold Cessnas, and flew a lot of 210's also. I'm sure I'll get torn apart for that one, but it was an honest mistake (It's been a long time).

-- Hawk (flyin@high.again), February 15, 2000.

My dear Mr. Ra,

Sir/madam...Which ever the case may be. It does you no good to throw sand in this forum. If you have a disenting view on a subject. You must put forth retoric to butress your observations. I am not an "Expert" on anything..Long ago I arrive at the point of knowing that there is a lot I do not know about my speciality/and trade. Apparently you have not yet matured enough to learn that lesson yet. That is unfortunate. Because I for one would like to learn your views, when presented with corresponding facts/sembulances of facts; and not off the cuff polly "I want a cracker" wise cracks that you have resorted to so far. I would suggest also that you do not resort to the "english teacher's gambit" also. None of us here are into purity of diction, spelling or verb splitting. But every one here still understands each other in spite of all that c.s.y2k malarky that goes on over there ( and you have resorted to here).

So...Mr Egyptian Lord of Light...Give us your reasoned respondse to Hawk's posting. No subtrifuge as they do at c.s.y2k. No pointing out his mispelling of (gimbal). No whining ang moaning "Oh no not another y2k gouly)"! If you have a position, then state it; and be prepared to defend it! Or else suffer the infamy of Y2K Pro and LL. Both of them have gone so far in their efforts to disrupt the forum. That even though they might try to be taken as being informative, and serious on a thread. No one believes them any more. So far, you have displayed the same tactics accorded to your compadres.

"As for me...I shall finish the game"!

~~~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 15, 2000.

Shakey, even in a system with a digital controller, the best thing to do is put the limit switch in series with the power supply to the motor. Fewer components in the path to fail. But in the MD-80, the power to the actuator is controlled in the end with switches and relays commanding the actuator to drive in one direction or the other. There is no absolute positioning loop even when the autopilot is driving the actuator -- it simply commands motion in one direction or the other to minimize the effort required by the servo driving the elevator.

Casper, I think what you're describing is what we called an auger on the farm when I was a child. A screw rotated in a tube in order to move grain, but it needed the tube to contain the grain. But the jackscrew doesn't have a tube to guide the stripped-off threads, so I'm inclined to think if the jackscrew stripped them off by continuing to drive at the end of travel, that they would either stick to the jackscrew at that end or fall out. But I may not have a good picture of what went on mechanically. Also, there are no tabs on the stabilizer, only on the elevators -- a difference that's perhaps subtle to some but nonetheless important.

-- Mikey2k (mikey2k@he.wont.eat.it), February 15, 2000.

Mikey, I "got your" line of reasoning on the physical locations...and the limit switches hooked up in series. Now one further question! Does this D.C. motor have a contactor? overloads etc. such as we have in other digitial motors (or really in any three phased motor/ single phase motor).

In some instances the relays with-in a contactor will sometimes close and will not open upon command. Thusly burning out the motor (after it has hit it's limts).

The matter of the "stringers" of thread from the gimbal nut is easy to explain. For an easy way to test this, just get out your drill motor and put a drill bit in. Next drill into a steel plate pushing down on your drill motor as hard as you can...You will note that during the process of drilling your hole. The steel shavings will start to come out as long stringer, and will follow the inset gove of the drill bit. This is what happened to the threads in the gimbal nut. Once the nut reached maxium extension/retraction. and could not travel any further. The Jack Screw continued it's efforts and became a "drill bit" drilling out the threads of the gimbal nut.

Sometimes I really, really wished that TPTB would not resort to digitial, when KISS would work as well, if not better.(By this I am refering to my control work, not the areospace industry).

Thanks in advance for the information.

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 15, 2000.

Mikey,

The stabilizer, or stabilator in this case..ie, an "elevator".... it controls the nose attitude... this is what we are looking at. there are always Trim Tabs of some kind on these control surfaces... TO CONTROL TRIM without pilot input to the controls... that's why it's called TRIM !!!!

Now... how did these SMALL control surfaces cause a crash?

It started with TRIM TAB Problems... how did it go to stripped threads in the gimbel nut of the 'elevator" ?

-- Casper (c@no.yr), February 15, 2000.

Another quick question Mikey,

Are you stating that these limits are series into the load (for those not into electrical terms-load is the high voltage feeder wires to the motor it's self)? If so...how are they able to stand the Amps. that they must be subjected to? In my experience, we always used the limits to switch off/on the contacts. Switching the load it's self would be ruiniously unnessary it would seem to me.

Thank you again

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 15, 2000.

Shakey, excellent observations! I strongly agree with the ideas that you are deriving from your experiences. Particularly while the autopilot is engaged, I think you are correct that the electronics would "talk" to the motor, rather than a simple on/off type of instruction. This was clearly not as much of a mechanical failure as some type of "control" failure. The control failure CAUSED the mechanical failure.

Thanks again. :-)

-- Hawk (flyin@high.again), February 15, 2000.

HAWK --- SHAKEY these PLC's you keep mentioning... are they somewhat the same configuration as the ones we use in the refineries? When the internal clock reads less than the external clock the unit cannot define so it sort of freezes in an open position or closed position? ...or if it is running to open it continues to run and visa versa? I might not have the specifics correct on internal and external clocks...but bottom line... what date sentive element could have been present that a y2k failure may occur...? could it be the calculating of distance and time...elevation and direction for auto pilot according to date? I'm sure how to asked the question except... can the embedded chips which are date sensitive be sensitive not exacly to the one day that people call y2k but at times the year is a factor in causing the chip to not read and then freeze in whatever mode it is in?

I'm just a moron when it come to aviation stuff...but I'm trying to understand everything I can...somewhere down the line, someone is going to ask me my opinion and I sure would like to have a coherent one... But to if you look back in history sometimes a moron says something moronish and the answer is found in it's interpretation or misinterpretation...

What common factors do we see in all these aircraft stablizer problems...? has someone constructed a board on evidences and tried to see if any of these planes had something in common other than flying after the roll-over date ... ? etc.? BRyan

-- S BRyan G III (sbrg3@juno.com), February 15, 2000.

Shakey, I don't know whether this information is related or not, but thought you would understand it much better than I, and it may be applicable here.

linear motors with digital controllers

Devices used in conjuction with linear motors:

"Linear encoders--with resolution high enough for the motion smoothness needed and signal transmit rate fast enough for the velocity required.

Servo amplifiers--selected for digital current closed-loop bandwidth of 2-5 kHz. High power may be required to accommodate high voltage and high current demands.

Servo controllers--should be digital, typically PID with feedforward on velocity and acceleration. Typical update rates: <1 msec on position; on the order of microseconds for velocity and acceleration."

Some motors used in aircraft guidance

"Typical Applications:

AC instrument servomechanisms
Aircraft guidance systems
Position controlled devices.

-- Hawk (flyin@high.again), February 15, 2000.

Dear Mr. S BRyan,

Sir, A officer of Foxboro controls made a rather surprising statement before the roll over. That of the fifteen thousand sites that their control systems where on,there was not a one of them that didn't have problems. What we found( when building and calibrating many systems.Some of them in updating exhisting refineries).That the chips where not all of the same manufactor. By this I mean, that the PLC/PROM/ROM 's would all do what they had been designed for. But that there was some on the black boxes which had chips in them which where capable of date functions but where not used for that function in their application (but still kept time any way).

Then there is the "marrying" of two/three/four different makes or types.

The closest example I can use is the movie "Toy Solders". If you will remember, some military reject chips came on the market at a fire sale price. And where used in toys. They performed the task given them in that slot of being a toy...But they also had other functional capabilities. Of course, the extent to which the cpu's went( in the movie) is so far outside of reality as to be just barely believable as a sci fi flick. But still the principal remains valid

Mr. Hawk...Sir I will examine your liner motor URL closer tomorrow. It comes off, to my poor old memory as being developed (or was being developed) with something to do with the mag lift rail train. It is far advanced over the old armature motor. And should do away with the nesessity of so many bearings (which would eliminate drag/heat/wear). And thusly deliver more power for the electrical buck than the older motors do.

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 15, 2000.

Shakey, allow me to help you out here as it would appear the air is getting a little stale at 40 feet.

(1). I guess my handle was a little too tricky for you. Rational 1 (Ra tion@L.1). I will agree that it could be somewhat clearer.

(2). Dont make the classic mistake of assuming that anyone who disagrees with your speculations is a Polly, Troll, or forum disrupter. Ive never seen the site you make reference of and there are many others who find you and Hawk to be out there a bit.

(3). Unlike yourself, I am playing no game and have no agenda. This forum has become a form of entertainment for myself and I hardly need the advice of a cyber-fool such as you to guide my activities here.

Come up for some fresh air son, its great up here on the surface.

-- Ra (tion@l.1), February 15, 2000.

SHAKEY -- HAWK, Did you guys read that post by the "Ra" or whatever, he's entertained by harrasssing people who are working! Weird...

Shakey, what purpose would these PLC's have to keep time if they didn't really use it in their functions or calculations? Would these PLC's convert date into an external problem if their functions didn't look at the date?...or is this controller that is on MD-80's one such controller that makes it's functions based on date? My question goes back to the PLC in industry that when 00 is read in some functions, the unit freezes a "gate" open, closed, running open or running closed... is this the type of controller that serves the stabilizer trim motor ... or ... as you stated: at "3:50 ..... The CVR was activated, and the pilots were heard discussing a problem with the stabilizer trim (only 3 minutes after the autopilot had been engaged) "... at 4:20 the plane went into an uncontrollable dive... do you think this motor kept running due to a "gate" continuing to run the unit? Is it possible that these pilots fought this continued running activity for 30 minutes and finally the running motion like a lthe sheared off the screw? ...or was this some kind of jam... where something just froze and and fighting against it for 30 minutes finally caused the thing to break?

It seems that something continued to run and lathed like cut the mechanism...sounds like electronic controller failure os some sort...it looks like we have a date change incident which is and has caused death. To the untrained mind...like mine... I don't think I'd send my family into the air just yet on the word of ... what do you call them?... TROLLS.... especially if they are visiting the site for entertainment it seems like they're getting off on these mishaps rather than sincerely concerned... By the way... what does TROLL mean?

Oh yeh, one more thing... HAWK you said we shouldn't worry too much about future crashes becuse they are investigating the problem and pilots will be more cautious as to using the auto-pilot mechanism...but what if there are more date sensitive components like this particular one which we have yet to see in the picture...just how many date sensitive controller devices are there in a commericial airliner?...just the ones that have major flight functions? Thanks guys...I think I'm starting to get an idea of whats going on... BRyan

-- S BRyan G (sbrg3@juno.com), February 15, 2000.

My Dear Mr. Ra...

I rather believe that you spend hours in raptured wonder, staring at the swirling dust mote in the sun light streaming down throgh a window pane. It is the elementay things which entertain (by your admisssion) you sir.

If I want entertainment...I would follow your postings. No content! But a lot of smoke and mirrors seem to be your style young person. I see you are an immigrant from c.s.y2k! I guess that since Milne and a few others have ceased posting over there, you have become bored.

I much prefer your original shorting of you name..Ra-ional sounds like Logic's little brother.. And even your low sence of humor has not reached that level yet. But you are getting there my friend.

And I see, from your words (and the lack of them) that you intend not to offer evidence of your future positions. Just take pot shots at the forum's posters.

I must say sir...I find you rather pathetic. To come to the forum to just inject jabs/ puns/ and polly nonsence.

Entertainment! If you would take a step back and view this forum in it's entireity; you would find the current news of the globe in these threads. No news paper, no media can or will cover the news (or publish it) that you find here.

-- Shakey (in_a_bunker@forty.feet), February 15, 2000.

My Dear Mr. S BRyan G,

Sir I aologize for not addressing yur post (I accidently sent my other one off before I was finished). But seeing as how this thread is nearing the end of it's board life (it will soon drop off into the archives). I believe that at some near future time, when there is a thread nearer the top. I'll try and give you a verbal "possible" chain of events( so far substancuated by the evidence), which I believe could have happened.

"As for me...I shall finish the Game"!

~~~~~~~~~~~~~~~~~~~~~~~~~~Shakey~~~~~~~~~~~~~~~~

-- Shakey (in_a_bunker@forty.feet), February 15, 2000.

SHAKEY, You've let me down... I thought you'd be into more intellectual entertainment than burned-out thrill seekers. I didn't know you liked smoke and mirrors...have you tried some of Hodini's tricks with mirrows and smoke...it seems that would be more entertaining than some defunked eygyptian sun god... OOpppps! I just went back to the site and found it stands for "rational" didn't read any of this persons comments after the first one a while back... I usually look at the signature before taking the time to read them...I really don't have time to waste on the brain dead...it also keeps me from getting angry not to read them... I just do the same thing to all the ones the forum calls TROLLS...but first I read their comments (usually discontented compliants) and then write it down in my mind to not anymore give them my time since I have very little... My question to you... Have you seent the newest post to TB2000 regarding the manufacturer of the horizontal stablizer? Now they are going to try to put it on "poor quality" I suppose? When when these people get it? I think that at this stage of the date change or roll-over...we are not going to see much change in the consciousness of the people since they have already harden their hearts and mind to believe what they believe at whatever the cost is! Its a shame to see a once great country reduced to rable because we let government convince us that they had everything under control... I haven't trusted government since VietVam... China makes horizontal stablizers for Alaska Airlines...big deal.. Chaina makes about everything for everybody... what about the actuating mechanism that rotates the jackscrew... HAWK said that it could be actiuvated by either the pilot or autopilot... does this mean to take the plane's actuating mechanism that drives the jackscrew off line if there is a problem...does the controller that switches the mechanism on and off ...can you do this if the PLC is frozen? I know they tried to override the ones at the oil refineries and they refused to respond...some basically shut down pipes, some opened and kept open lines and then it is suspected that the valves opening when the PLC engaged 00 in its calculations continued to drive at an open gate until they overheated and expoded.

-- S BRyan G (sbrg3@juno.com), February 15, 2000.

Mr. SBRyan sir..

I suspect you are attempting to provide us with some important information but Im getting a severe migraine sorting through your words. Slow down just a little and look at what you write. I apologize if you are offended but it is difficult to get your message as delivered. Do you have a background in control automation systems, programmable logic controllers, etc.? If we are to believe that there could possibly be a link to date sensitive embedded chips, why are we now seeing this occur during the first few days of February? What could be the motivation for all of the real experts to avoid resolving these problems?

-- Sifting (through@the.rubble), February 15, 2000.

Shakey, the motor isn't as large as you might think. While the motor might rotate at 1000's of RPM, its output shaft goes through reduction gears such that the primary motor takes around 45 seconds to travel from one stop to the other.

-- Mikey2k (mikey2k@he.wont.eat.it), February 15, 2000.

S BRyan GLooks like we done found the Moe.

-- Ra (tion@l.1), February 15, 2000.

Dear Sifting:

You posed two questions:

"If we are to believe that there could possibly be a link to date sensitive embedded chips, why are we now seeing this occur during the first few days of February?" and

"What could be the motivation for all of the real experts to avoid resolving these problems?"

It could be that the problems were triggered around the same time and that they all became evident about the same time. There could have been a number of weeks between the time the problems were triggered and the time that they got to a stage where they could cause failures.

I am not an expert, but here are three possible things that I have seen mentioned elsewhere that seem to me could have been involved:

1) buffer overflow

2) function overflow

3) annual maintenance scheduling (if scheduling functions are not Y2K compliant, and a date of 1900 comes up, that alone could shut down operations or trigger a failure).

As regards your second question regarding why experts would avoid looking into these problems, I would suggest several possibilities BEYOND the regular psychological barriers, bureaucratic constraints, and legal and insurance disincentives:

1) that few people have the training and expertise to troubleshoot the kind of interconnected set of problems that could have been involved with the Alaskan Airline crash;

2) that fewer still might be expected to found at the NTSB or FAA; and

3) that even fewer might be expected to be to be found on a maintenance crew.

What if this particular crash did involve a complex set of cascading problems, involving both mechanical and automated systems? And what if fewer than 50 people in the world had the training, expertise, and experience to sort out such a complex set of interconnected problems? What if none of the experts with such expertise were in touch with the NTSB, FAA, or Alaskan Airlines, etc.? What if none of them had ready credibility with NTSB, FAA, etc.....?

Maybe, just maybe, we have reached a point when only a few people will be able to understand complex problems that require expertise in specialized and overlapping areas of technology. Maybe we have reached a day when others who need to understand what those few know, do not even know the right questions to ask, let alone have the understanding to recognize when an explanation is or might be relevant?

-- Also Sifting (Also Sifting@through.theclues), February 17, 2000.

I believe that the NTSB either has the expertise or the ability to call on other experts to help out if anything points at a computerised system.

However, I doubt that they'd call on Hawk.

-- Mikey2k (mikey2k@he.wont.eat.it), February 17, 2000.

Re Mikey2k's comment:

Does anyone know the name of any expert who works for the NTSB or FAA or consults with them who has the range of expertise that I described?

Has anyone heard the NTSB make any mention of the possible role that automated systems might have played in the Alaskan Airline crash or in other reported problems involving the MD80 series of planes?

-- Also Sifting (Also Sifting@through.theclues), February 18, 2000.