Servomotors for Airline stabilizers - any experts out there?

greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread

Before any idiots like "Liberal Hater" start telling me that I'm swimming in sh!t, I'll tell you right now I don't know jack about servomotors. That's why I'm asking for info from anyone who might know more about them. I did read that these things that control the motion of the stabilizers rely on timed pulses to adjust their relative position.

servomotors use time ratios for pulses

Do some of the ones used in aircraft have embedded chips in them to send the timed pulses to the motor? Or do they rely on some type of clock or timer system seperate from the motor that could be using faulty chips or software to send the time signals? IMO, these things seem highly suspect in some of the recent problems we have witnessed, including Egypt Air 990. I'm not completely convinced that the pilot was trying to commit suicide, maybe he was just trying to get the stabilizers back to normal position.



-- Hawk (flyin@high.again), February 03, 2000

Answers

A good question, Hawk. A retired 747 pilot brought up the topic of servo's in one of the MS990 discussions on another board, but it wasn't pursued. Wish we had more avionics engineers participating in these discussions!

-- Rachel Gibson (rgibson@hotmail.com), February 03, 2000.

Put this speculation to rest. Servo motors use PWM (Pulse width modulation)to control speed and torque relationships. The 'timed pulses' are really nothing more than pulses whose width is adjusted vs the adjustment of the width of the non-powered state.

That said, what controls the widths? Usually an 'embedded controller'. Is the embedded controller sensative to 'dates' as we know them in terms of the control functions? I doubt it. The error reporting functions may be affected. Is it possible that a 'fly is in the ointment' with interaction between the 'executive', 'control' and 'error reporting' portions of the firmware such as error buffer overflow, etc? Possibly. But you can bet that 'failure pathways' have been rigorously designed and tested for this type of controller since liability issues are supreme in air service.

From what we've seen so far it appears that there has been no collective design errors propogated by avionics embedded engineers.

-- ..- (dit@dot.dash), February 03, 2000.


The NIST reported that an embedded chip
can have problems even though there is
no apparent "means of setting date and
time, i.e., no apparent real-time clock
calendar or no data entry mechanism."



-- spider (spider0@usa.net), February 03, 2000.

Someone wants to show me a servo-motor controller with anything like a date error/fail WRONG issue and I'll eat the bugger.

.

.

.

.

without salt.

Chuck

-- Chuck, a night driver (rienzoo@en.com), February 03, 2000.


without salt

That might be a little difficult as the ocean
is quite salty!

-- spider (spider0@usa.net), February 03, 2000.



The MD80 series and also the earlier DC9's ave two horizontal stabilizer trim motors, a primary and an alternate.

The primary trim motor is actuated by the "pickle switches" on the captain's and first officer's flight control yokes. Both "pickle switches" must be activated together to get trim motor actuation. One switch is a brake release on the trim motor, the other switch provides power to the motor. Movement of the switches in a forward/upward direction results in nose down trim. Movement of the switches in a rearward/downward direction results in a nose up trim. The actuation in either direction causes an aural warning tone in the cockpit. The primary trim motor is powered by the primary trim circuit breaker, directly behind and above the captain's seat.

The alternate trim motor is actuated either by movement of the alternate trim control switches or the autopilot if engaged in at least a minimum mode of altitude hold. The alternate trim control switches are located on the throttle quadrant near the power levers. These alt trim control switches are also in pairs, one for brake release and one for actuation.

Both the primary and alternate trim motors are located in the vertical stabilizer at approximately the area where the horizontal stabilizer intersects the vertical. These motors produce leading edge horizontal stab up and down motions through a jackscrew assembly. The jackscrew has limiting devices designed into it. The horizontal stab main bearings are aft of the jackscrew and motor assemblies. The horizontal stab main bearings are subject to wear, pitting and corrosion and are potential sources of failure, as are the jackscrew, stops, motors, connectors, wires, mounts and structures.

There is a guarded switch in the cockpit which when unguarded and then actuated will stop a runaway motor. Also, pulling the circuit breaker for the associated motor will also stop a runaway motor. Actuating any control switches in the opposite direction to current movement will stop the movement of the horizontal stab.

The word 'trim' or the phrases 'being in trim' or 'being out of trim' are particularly important in understanding and discussing the flight of an aircraft. MD80's elevator and horizontal stabilizer actuations are designed in one way to work together to maintain stabile and level flight whether the aircraft is ascending, maintaining altitude or descending. If the autopilot is engaged and the elevators are 'out of trim' for a pre-determined/programmed time period, the autopilot will issue commands to move the horizontal stab in the required direction to bring the elevator back into a trimmed or faired condition. This means no offset of the elevator once the stab is moved the required distance up or down. The autopilot uses the alternate trim motor. It is a smaller and slower moving motor than the primary trim motor. If the 'out of trim' condition is sustained long enough the autopilot will automatically disengage, which represents to the flight crew that something requires their attention. The autopilot trimming using the alternate trim motor occurs routinely during flight as well as autopilot commands to the elevator servo actuator. The servo actuator is mechanically attached to the flight control cables and is in mid-ship position some distance from the tail. The breakover slip clutch release of the servo actuator is approximately 31 inch pounds. It's force can be easily over-ridden by manually push forward or rearward on either control yoke in the cockpit. The autopilot will automatically disconnect itself under any of a number of preset conditions. Also, the autopilot can be manually disconnected by actuating disconnect switches on either control yoke, pushing the autopilot actuation levers to a non-engaged position or pulling the autopilot circuit breakers.

What do we have left?

If the crew experienced faulty commands from the autopilot, they would see changes in their cockpit instruments (flight director, etc.) and aural warnings, most likely. If they were 'off altitude', they would attempt to get back on assigned altitude by whatever means were available.

If the primary and alternate trim motors were unable to maintain level and stabile flight, then the cause of the failure would remain somewhere in the following areas:

1) The primary trim motor, connectors, wiring, switches, etc.

2) The jackscrew assembly, mounts, stab attachments, etc.

3) The horizontal stabilizer main bearings, clearances, etc.

4) Tail icing due to a failure of the tail anti-ice system, etc.

5) An undisclosed and unlikely failure of the mach trim actuator (it prevents nose tuck at high speeds), etc.

6) Structural failure in the tail area caused by metal fatigue, fastener failures, etc.

7) Preflight or inflight collision with an object or bird sufficient to render significant damage to tail structures, etc.

8) A combination of any of the above mentioned causes, as well as, other potential failures, including but not limited to possible human error or other causes, etc. being contributive factors.

(Any of these descriptions may contain error and should not be relied upon).

-- snooze button (alarmclock_2000@yahoo.com), February 03, 2000.


Hey there-Hawk- That was a great post and the answers seem to be right on target. I appreciate more you asking questions than trying to answer them. Keeps things rolling along better. That stabilizer might have had a jackshaft screw that broke because of metal fatigue if they find out it wasn't the fault of stabilizer trim.

-- Liberal Hater (liberty@bell.com), February 03, 2000.

May best guess is probable failure of one of the horizontal stabilizer's main bearings with one or all of the following: jackscrew faults, faulty electrical connectors on the primary trim actuator, primary trim motor actuation wiring faults(even in the cockpit "pickle switches") and/or severe tail icing.

-- snooze button (alarmclock_2000@yahoo.com), February 03, 2000.

I have experience with servo's as you can see in this picture. These are older ones and are the actual ones that were used in older aircraft. You can see the designation on some of them, the ones on the left door top to bottom= SU01, SU02 etc. For once I have actual "proof" that I know about something :o)

Servo's allow for linear smooth increase or decrease of voltages, done better by analog than digital (which must have the increments "smoothed" out.) The smooth increase/decrease in voltages allows for the smooth movement the flight control "edges". In aircraft, "chips" are not used in these systems due to their potential for failure-PERIOD.

In the systems I am familiar with, the voltages are applied to electric motors or hydraulic actuators which move the device (flaps, slats LE and TE devices.

These devices are analog, electromechanical devices in which an electrical input determines the position of the armature of a motor.

No where is there anything to do with a clock.

as for this- That said, what controls the widths? Usually an 'embedded controller'.

No. by now people associate "embedded with digital or computerized system with chips-this is not the case in aircraft flight control systems.

Is the embedded controller sensitive to 'dates' as we know them in terms of the control functions? I doubt it.

Not even close-this is not the case in aircraft flight control systems.

The error reporting functions may be affected.

Not even close-this is not the case in aircraft flight control systems. You are speculating that there is a computerized error reporting system, there is not- an electro/mechanical method is used to determine the position of the device. Is it possible that a 'fly is in the ointment' with interaction between the 'executive', 'control' and 'error reporting' portions of the firmware such as error buffer overflow, etc.? Possibly.

This is a continuation of your SPECULATION that there exists some form of digital computerization of the system-there is NOT-so your speculation is moot. You cannot attribute the functions of a (digital) computer into the system of electro-mechanical/hydraulic device. You are speculating dash dash dit dit dash, Please make that clear on this thread.

It is this kind of speculation that caused so many erroneous beliefs to be propagated about all kinds of potential problems with devices due to Y2K.

I do not wish to be rude, but since you do not know whether or not an aircraft uses digital (computerized) devices on their flight control systems, it would have been better to not answer than to speculate what could or would happen or how they would function if the device were indeed computerized.

Unfortunatly someone will read what you have written and assume that they are being used and go on to assume that they may have one of those "unused hidden clocks" in them (which do not exist, but are believed to exist by so many) and the idea of problems with the (nonexistent digital devices) will snowball until it is common belief.

Basically you are saying, I don't know if this is how they are made, but IF they are made this way, this is how they would work and this is what they would do and I believe they would or would not do this or that.

Suddenly we will have people believing that the flight control systems on aircraft are moved by computer. No amount of reassurances will dispel that belief.

So it is best not to speculate in the first place.

As to the original question-Aircraft manufacturers do not use computers or computer chips (integrated circuits) or systems anywhere in aircraft that puts the aircraft safety in jeoperdy.

I am being emphatic about this because it is important to nip any possible suggestion of this in the bud before speculation leads to rumors which lead to false assumptions.

An example of the "cycle" discussed is like your gas lawn mower, the dynamo's have an electrostatic field which picks up voltage when the motor spins. The cycle comes from the time where the voltage starts to increase, reaches it's peak, and decreases back down to zero.

****shakey**** you can probably explain it clearer than I did.

-- Cherri (sams@brigadoon.com), February 03, 2000.


Snooze Button, I worked on simulators for the Boeing aircraft(727,737,747) back in the 60's. At that time, the motor driving the ball nut of the jackshaft for trimming the horizontal stabilizer was hydraulic. There was a cable that ran from that nut all the way back to the cockpit. In the cockpit was a wheel(about 12 in. dia.) which was driven by the cable. The pilot/co-pilot could manually trim by turning the wheel or he could hit his "pickle switch" and the hyd. motor would drive the nut, causing the jack shaft to move the leading edge of the stabilizer up or down. In the event of a runaway (any condition causing the stabilizer to head for the extreme up or extreme down position), the pilot/co-pilot could manually grab the wheel and stop the runaway. The real danger, in my opinion, is when the stabilizer is in an extreme position since the elevators do not have enough control of the pitch attitude to overcome the great imbalance. Talk of a jammed stabilizer causing the crash is off the mark unless it is jammed in an extreme position. If, however, the stabilizer is loose due to bearing or jackshaft failure, then all bets are off since the elevator controls could be fouled.

I know this has been long winded, but does anyone know if the MD-80 has this cable connection to the stabilizer system or is the whole thing fly by wire?

-- Roberto de Avionico (mainman@iserv.net), February 03, 2000.



How is that proof - I can't read your name tag :-0

-- Proof- (idon't@thinkso.com), February 03, 2000.

Cheri's al lot cuter than I would have thought!

; )

-- Duke1983 (Duke1983@aol.com), February 03, 2000.


Let me state at the outset that there is no reason to believe that a date function is involved in the stabilizer control.

But Cherri, I must disagree with your statement "Aircraft manufacturers do not use computers or computer chips (integrated circuits) or systems anywhere in aircraft that puts aircraft safety in jeopardy." I myself have been involved in the design of aircraft systems involving functions that the FAA regards as critical: the display of attitude (pitch and roll), altitude, airspeed. Newer systems and even those more than a decade old are designed using microprocessors. NONE of these systems that I have been involved with use dates at all. The software for these systems is developed to strict standards required by the FAA.

From my experience with aircraft trim systems, what I know about aerodynamics, and what I've read about the incident here's my speculation about what happened: a malfunction in the trim control system allowed the trim to run nose down but not nose up. The crew did not recognize this quickly and the nose-down trim got rather large, meaning that the crew would need to pull on the control yoke with a great deal of force. News reports have indicated a nose-down trim and also that air traffic control lost contact after the crew indicated that they planned to lower the flaps. With the low-wing configuration of this aircraft, lowering the flaps and/or landing gear probably adds more nose down force. If lowering the flaps pushed the nose down before the crew pulled it up, then the resulting dive would increase airspeed and perhaps require even more force on the yoke to keep the aircraft from diving.

Again, this is speculation and the flight-data recorder should prove or disprove my conjecture.

But as far as a computer date problem being involved -- no way.

-- Mikey2k (mikey2k@he.wont.eat.it), February 03, 2000.


Cherri,

I think it is safe to assume that servomotors have changed a bit since World War II when that picture of you was taken. After all, in those days they didn't even have embedded chips.

The process of converting the voltage of electricity to a pulse train could be handled very effectively with an embedded system instead of analog circuity, and some type of time reference would be needed for the embedded system to produce the "pulse period times" (i.e. clock).

-- Hawk (flyin@high.again), February 03, 2000.


Okay, I take the plunge of leaping faith, and challenge a question to them. Cherri, you say the Military would take no risk at embeddeds, I do not have any knowledge, I have more than once, depended on the kindness/knowledge of strangers. From your pix, you were enlisted Military. Probably made your way to Chief, and ain't you strutting your stuff. More masterful minds, than yours, were doing programming, before you were a concept. They said: problems in the landing gear and infrared. Heaven only knows, what else.

-- We All know (asm@llpiece.pie.com), February 03, 2000.


Hawlk, *grin*... it was the last part of the Viet Nam war...geeze, I'm old, but not that old.

The picture is at Carswell AFB, TX, the hydraulic cabinet of the B-52 D. Smae servo systems as in the aircraft, and the same as in the old ATC computers. Unbelievable that they kept them running for so long. -- Roberto de Avionico

You DID? Were you in engineering or a sim tech? You were over on E.Marginal. Were you there when the 747 hit the concrete?

snooze button,

You know aircraft systems pretty well don't you? Where did you learn them? I'm familiar with the Boeing's but the systems in Boeing aircrat are really redundant, I am not familiar with the Micky Dee systems, except I will not fly on a DC-9 or DC-10. The cockpits are like the old military fighters, get spoiled on Boeing aircraft.

Over at the old Longacres facility they have some company who came in and took over Flight Crew Training and they claim they can get you in the sky in 60 hours, the pilots don't even have to learn the aircraft systems any more, no wonder there are so many crashes!

-- Cherri (sams@brigadoon.com), February 04, 2000.


But Cherri, I must disagree with your statement "Aircraft manufacturers do not use computers or computer chips (integrated circuits) or systems anywhere in aircraft that puts aircraft safety in jeopardy." I myself have been involved in the design of aircraft systems involving functions that the FAA regards as critical: the display of attitude (pitch and roll), altitude, airspeed. Newer systems and even those more than a decade old are designed using microprocessors. NONE of these systems that I have been involved with use dates at all. The software for these systems is developed to strict standards required by the FAA.

Mikey2, I agree, BUT they still have the old basic instrumentation as back-up. There is an HSI, altimeter, ADI and a few others that can be used if the ones you are talking about fail. I should have clarified that.It was getting boring to fly when the digitalized instruments and the flight computer came aboard almost 2 decades ago.

Can't see my nametag, Oh..true there, but I still look like me, but I guess you can not see me huh? I just looked in the mirror, and yep! it's me * :o)

-- Cherri (sams@brigadoon.com), February 04, 2000.


Snooze Button,

I worked at a division of McDonnell Douglas which manufactured simulators for Boeing and various Airlines. I am an engineer, mostly dealing with things electromechanical. I was responsible for the design of the control "feel" systems as well as the motion bases. I got to know a lot about the Boeing aircraft being designed then because I got to see the drawings in order to simulate the operation. For instance, I got to see the drawing for the quad redundant hydraulic actuator for the 737 rudder. At that time it cost about 100k and was very complicated mechanically. This very same unit is suspect in a number of 737 crashes that appear to have been caused by rudder hardover. By the way, from the voice recorder reports, it appears that the crew was fighting a stabilizer trim runaway on aircraft involved in the recent crash. I am still in the business, working for an outfit which provides e-m actuators to the commercial aviation world (mostly bizjets). But I am starting to count down the weeks until the big R. Roberto de Avionico

-- Roberto de Avionico (mainman@iserv.net), February 04, 2000.


Cherri, the primary instruments in many aircraft are microprocessor based electronic- there are even common acronyms EADI and EHSI to denote the electronic version of these vs. the old electro- mechanical. Commonly the standby ADI is electromechanical, but there is no regulation or guidance from the FAA that prohibits all indicators from being electronic, provided they are reliable enough. If you can point to a FAR or AC that contradicts this, please post it here.

-- Mikey2k (mikey2k@he.wont.eat.it), February 04, 2000.

Michael, They do not stipulate that aircraft have landing gear either, but no one would make an aircraft without them. Well except for those that land on water :o)

Yes the primary aircraft flight instruments are digital instruments, which are directly wired to "black boxes" in a "bay" where they are bolted down. The boxes are then interconected to other boxes and aircraft systems by electric cables.

The old electro-mechanical instrument as backup are only common sense, gyrosycro cannot be controlled digitally. If any aircraft manufacturer attrempted to develope a cockpit without these for backup there are just too many people involved who do have brains and would stop them. It would be about as smart as making a car without brakes.

Now Boeing is anal when it ccomes to redundency,there are four ways to lower a landing gear on a 737, the last being where you go to the passenger compartment and open a panel in the floor and hand crank down the landing gear.

Now that they absorbed McDonald Douglas, there is only Airbus who makes commercial aircraft. Russia has thiers but...welll...

Smallr aircraft, I have no clue of what they use, but sence there is a huge amount of interaction between all manufacturers and aircraft parts manufacturers, it stands to reason that anyone who would attempt an aircraft that carries humans in it without analog backups. Now what the military has planned for the future.. who knows.

The FAA needs to be taken apart and restructured, it is, in my opinion, too corrupt right now where the safety of passangers is concerned. It has taken too many deaths for them to take action in the past few decades.

Also the company who took over flight crew training at Boeing claims they can put you in the air after 60 hours and you don't have to learn the aircraft systems. add that to the fact that there are not that many pilots with military experience these days and you are asking for an overwhelming increase in aircraft crashes.

Training time is too important to skimp on, the reactions of that pilots need to be "instinctual"..they have to have enought training to so they can react without thinking.

As explained here, there are backups. They are perfectly aware of the handicaps of digital equipment.

Primary Flight Instruments

In order to duplicate the functionality of the 737-300 flight deck, any change to its integral presentations had to be minimal in the following displays on the next-generation 737 flight deck:

EFIS/MAP.

Analog/electromechanical instruments.

EFIS/MAP.

The 737-300 EFIS/MAP system (figure 1) uses CRT displays for the primary electronic attitude direction indicator (EADI) and for the electronic horizontal situation indicator (EHSI). Some operators use electromechanical attitude direction instruments (ADI) rather than the CRT EADI. The EADI presentation includes autothrottle mode annunciation, autopilot mode annunciation, and vertical speed tape option.

Superimposed over the navigation data on the EHSI are weather radar and traffic collision avoidance system (TCAS) targets.

ANALOG/ELECTROMECHANICAL INSTRUMENTS

Primary Flight Instruments

In order to duplicate the functionality of the 737-300 flight deck, any change to its integral presentations had to be minimal in the following displays on the next-generation 737 flight deck:

EFIS/MAP.

Analog/electromechanical instruments.

EFIS/MAP.

The 737-300 EFIS/MAP system (figure 1) uses CRT displays for the primary electronic attitude direction indicator (EADI) and for the electronic horizontal situation indicator (EHSI). Some operators use electromechanical attitude direction instruments (ADI) rather than the CRT EADI. The EADI presentation includes autothrottle mode annunciation, autopilot mode annunciation, and vertical speed tape option.

Superimposed over the navigation data on the EHSI are weather radar and traffic collision avoidance system (TCAS) targets.

ANALOG/ELECTROMECHANICAL INSTRUMENTS

These instruments on the 737-300 are arranged in the basic "T" scan familiar to most flight crews. They consist of a "round dial" electromechanical airspeed indicator, altitude indicator, and vertical speed indicator.

These instruments on the 737-300 are arranged in the basic "T" scan familiar to most flight crews. They consist of a "round dial" electromechanical airspeed indicator, altitude indicator, and vertical speed indicator.

http://www.boeing.com/commercial/aeromagazine/aero_04/textonly/ps02txt .html

-- Cherri (sams@brigadoon.com), February 05, 2000.


Cherri, you stated that they (the FAA) "do not stipulate that aircraft have landing gear either." See for yourself the Federal Aviation Regulations concerning air transport category aircraft, and do a simple text search for landing gear.

FAR part 25

You also make a statement "gyrosycro(sic) cannot be controlled digitally". Traditional gyroscopes are NOT NECESSARY for attitude references -- read up on ring laser gyros. No moving parts, and heavily software dependent.

Your criticism of the FAA may have some merit but the fact that they don't explicitly require analog backups is not their failure. Despite the FAA's flaws, flying is still the safest way to travel.

Your paste-in just tells me that some 737's have mechanical instruments and others electronic, and that the electronic instruments mimic the presentations of the mechanical instruments that they replace.

-- Mikey2k (mikey2k@he.wont.eat.it), February 06, 2000.


The following question and comments are from an embedded expert who I don't believe has been following this thread. Any comments?

"what about the stabilizer problems on the md series of planes? These servo motors which control the stabilizers pulse based on a timer which is chip based. The servo motor does not care about date, but may be a buffer overflow from that part of the chipset which does the date calcs anyway."

-- md 80 series auxiliary questioner (md80series@remaining.questions), February 06, 2000.


Aha! Thanks md, glad to see someone has finally figured it out. I recall some programmers saying that even though a system may not need to use a date, it is sometimes written into the coding as a method of calculating time increments. If a non-compliant chipset like that were linked to the main computer showing a 2000 date, you'd eventually get buffer overflows, and that's why these things are all starting to happen around the same time.

-- Hawk (flyin@high.again), February 06, 2000.

Hey there-Hawk- You were all right for a couple of days now your up to your nipples in poop!

-- Liberal Hater (liberty@bell.com), February 06, 2000.

Eat some of this poop you ignorant right-wing twerp...

The Bulletin 1391 is a Pulse Width Modulated, single axis AC servo drive

The 1391-DES digital drive has the same features as the 1391 series products, but takes advantage of a microprocessor-based control structure.

-- Hawk (flyin@high.again), February 06, 2000.


Here, swallow some more poop, Liberal Hater...

Boeing MD-80 and MD-90 Family

You too Cherri, planes have changed a bit since the Vietnam days...

Technology advancements in the MD-80 include aviation's first digital flight guidance system.

-- Hawk (flyin@high.again), February 06, 2000.


Hawk, I and others have explained how the stabiizer actuator system works. NO embedded processors involved.

While microprocessors such as this 1391 you mention may be used in some applications, aircraft trim is not one. Aircraft power supplies are 115 VAC 400 Hz and 28 VDC. Actuators run on 28 VDC. Does this 1391 have a date function? Why would it? I seriously doubt that it even has the capability.

As far as this "experts" question -- this nonsense about a non- compliant chipset's date function overflowing into a buffer is just that: nonsense. A calendar chip would have its own registers that would be available if the processor software accesses it. But if the software doesn't access it then it has no effect.

Hawk, it's becoming clearer that you are a disappointed doomer. The difficulty you have accepting knowledgable explanations why a Y2k bug is not involved here but eagerly embrace "expert" speculation demonstrates that. If you invested too much (mentally and/or monetarilyy) in a Y2K disastrous outcome, just lick your wounds and be happy that nothing of any consequence has happened instead of wasting your time looking under rocks for problems.

No, I'm not an abject polly. I prepared to a level higher than 99+% of the population for a what I saw as possible Y2k disruptions, and plan to keep a high level of preparation in case of some natural disaster. While I felt that there was a POSSIBILITY of Y2k problems, I felt the PROBABILITY was low. So I also prepared for the possibility that there wouldn't be any serious problems. I didn't max out my credit cards and clean out my 401k account. Could there be problems? Sure, but I think most of them are relatively minor. When I had to use the DOS function to correct the non-compliant '486 calendar function, should my company have had a press conference to announce it? Of course not. If a problem can be fixed before it impacts a customer, then the only people who care are those who have to put in some overtime to fix it. Could there be serious problems? Sure, but we won't be able to sort them out amongst the uninformed speculation on this forum.

-- Mikey2k (mikey2k@he.wont.eat.it), February 06, 2000.


If Cherri can "prove" that she knows something by posting a picture of herself, surely I can post one of myself to prove the same!

-- Steve Heller (stheller@koyote.com), February 07, 2000.

Thanks Hawk for all your contributions. Very interesting to say the least.

That is quite an eyeopener that the MD-80 series includes "aviation's first digital flight guidance system". What other planes use digital guidance systems?

Wouldn't such digital guidance systems also include digital annual maintenance scheduling. If that is the case, then once a year a date would be accessed. Say that that date was January 1. Consider the possibility that the date had not been remediated correctly or at all or that it had failed to rollover. It could take weeks for the buffer to overflow if the date were incorrect.

Mikey noted that if the date sensitive software doesn't access the chip then it has no effect. I am not an embedded expert, but it would seem that at the time that annual maintenance scheduling kicks in, the chip would be accessed.

-- md 80 series auxiliary questioner (md80series@remaining.questions), February 07, 2000.


LOL Steve, that's great! Heeee heee heeee heeee hee :-)

Cherri is an old maid who is living in the past because she has much fonder memories of her more youthful days. That's why she saves 40 year old pictures of herself and reminisces about the way the good ole' B-52's were built, before everything went digital and became too complicated for her to understand. Hell, it took her several years just to learn HTML that 5 year old kids have learned in a couple days!

-- Hawk (flyin@high.again), February 07, 2000.


ok, ok, since we're posting photos of ourselves, here's one of me after the surgery...

...but before the swelling went down.

pan

-- panjandrum (panjandrum@samfoote.net), February 08, 2000.


So HAWK, exactly what would you need to see to be convinced that the lady in question was truly the NORTH end of the northbound horse?? I have a set of e-mails from a set of folks who have verified her credentials, through CURRENT equipment. Unfortunately, they are confidential. You can take it from me or not but the lady DOES represent the Horse's MOUTH on this.

# 3

sheesh. i spent enough personal capital on this.

-- Chuck, a night driver (rienzoo@en.com), February 08, 2000.


Chuck,

I realize all you vets like to stick up for each other, and that is commendable, but let's be objective here. Cherri is what as known as a "dinosaur" in terms of her computer expertise. The closest thing she has seen to complex digital electronics is the PC with which she is posting on the Internet.

When she says things like this, which are completely innaccurate, she loses a great deal of credibility in my eyes...

"This is a continuation of your SPECULATION that there exists some form of digital computerization of the system-there is NOT-so your speculation is moot. You cannot attribute the functions of a (digital) computer into the system of electro-mechanical/hydraulic device. You are speculating dash dash dit dit dash, Please make that clear on this thread.

It is this kind of speculation that caused so many erroneous beliefs to be propagated about all kinds of potential problems with devices due to Y2K."

NOT speculation, reality

"As to the original question-Aircraft manufacturers do not use computers or computer chips (integrated circuits) or systems anywhere in aircraft that puts the aircraft safety in jeoperdy."

wish that were true, but not even close

Perhaps I could overlook the fact that she doesn't know anything about more recent electronic technologies, but it is hard to overlook when she is also being rude and snobbish about it. Sorry, but that's me.

-- Hawk (flyin@high.again), February 08, 2000.


ROFLMAO- yep "old maid" is a good discription of me...NOT. Hawk you seem to think that I worked on one type of equipment and stropped at it. Not true, fortunatly for me, I was working all of these years on the newest equipment as it came out, up to what exists now. That gives me a lot of more experience than you give me credit for. There are a lot of advantages of knoing how the old stuff worked and learning the new stuff as it comes out, that way there are not gaps in my knowledge. People cannot learn what I have in a few years of college, experience alone is one of my biggest advantages. Unfortunatly technology is so specialized these days that there are few oppertunities to gather a wide range of knowledge. I am proud of my age (47) it sure beats the alternative.

Steve,

Where did you get that picture of my Father?

-- Cherri (sams@brigadoon.com), February 08, 2000.


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