Alaska 261

[Mitch Cronin]

Earlier today, I saw the Discovery Channel piece on that sad disaster... I knew the meat of the story before of course, but they did a reasonably good job of putting together all the details...

I can't help feeling the need to offer a ridiculously lame apology for my maintenance brethren for that one... what an incredible let down! ... a total failure of such a basic yet fundamental service we're supposed to provide! Wow!

I wanted to ask... Were QRH's and/or training changed to reflect what was learned from that, afterward? The film I saw today made the assertion that the crew had inadvertantly exacerbated the trouble by continuing to try to make the stab move... Have there been any kind of cautions added to deter such attempts, should your stab "jam"?

[J.O.]

Mitch:

I appreciate the emotion you must have felt after seeing that story. I'm sure your emotions are similar to the ones we pilots feel when we read the transcript of accidents such as the KAL crash at Guam. It's never easy to see our colleagues fail so miserably.

In the end, the aircraft spiralling out of control was a tragic metaphor for the way that the AS maintenance sytem was allowed to put more emphasis on an on-time performance record and financial constraints than on safety. To be honest, I have a hard time understanding how it got that way. That those involved didn't appreciate the potential consequences (i.e. the death of colleagues and customers) is difficult to fathom. Maybe this is harsh, but I hope that the people who made that happen never go to sleep at night without thinking long and hard about what their negligence lead to in the end.

[boestar]

Well Said...

B

[handyman]

I wanted to ask... Were QRH's and/or training changed to reflect what was learned from that, afterward? The film I saw today made the assertion that the crew had inadvertantly exacerbated the trouble by continuing to try to make the stab move... Have there been any kind of cautions added to deter such attempts, should your stab "jam"?

A terrible accident indeed!

Just as a comment to your question,

B747-400 QRH

Jammed or Restricted Flight Controls

Jammed Or Restricted System........Overpower

Use maximum force, including a combined effort of both pilots, if required....

etc....

etc....

The B747-400 has shearouts which allow half the rudder or elevator control to be regained if a jam occurs and an override mechanism for the ailerons which allows an independent control wheel to function should a jam occur. The MD-80 must not have had these back-up features.

[Mike Lavoy]

...The MD-80 must not have had these back-up features.

If I remember correctly (Mitch you just saw the program, correct me if I'm wrong), the Alaska Airlines A/C had no fail-safe mechanism built in to the horizontal stab. The jackscrew got so badly stripped of its threads that when the pilots eventually broke it free, it hit the 'retaining nut' a couple times and broke it off. At that point, with the stab at full deflection, there was nothing the pilots could do.

[Mike Lavoy]

That's enough speculating on my part, here's what the NTSB had to say:

Alaska 261 NTSB Summary

Alaska 261 NTSB Full Report

The latter link is to an extensive report.

"3. Conclusions

3.1 Findings...

...16. Alaska airlines dispatch personnel appear to have attempted to influence the flight crew to continue to San Francisco International Airport, San Francisco, California, instead of diverting to Los Angeles International Airport, Los Angeles, California."

What possible reason(s) could they have had for wanting the flight to continue to SFO? As soon as they were aware of the dire circumstances, they should have fully supported an immediate landing, wherever possible...in the interest of safety.

...Maybe this is harsh, but I hope that the people who made that happen never go to sleep at night without thinking long and hard about what their negligence lead to in the end.

These type of people make me sick to my stomach. I also hope they don't sleep at night. And no, it's not harsh.

[Mitch Cronin]

That's right Mike... The "stop" on the bottom of the jackscrew (not meant to be a physical vertical stop with stripped jackscrew nut threads! - but rather to stop the turning of the screw in the event of runaway or perhaps improper rigging... and used on many jackscrews as a reference for rigging ) was - for a time - all that held the thing from flying apart... eventually, extreme loads combined with continued attempts to trim caused that to fail.

Cpdude... I don't know the MD80, but I'm not aware of any large aircraft that won't allow one side or the other of a primary flight control to break free, or be controlled independantly of the other side, somehow when necessary... unfortunately, even on your 47's, the stab cannot be controlled by anyone once the jackscrew's threads are stripped clean. What would that QRH say about the stab when jammed? Does it not have a reference specifically for a jammed stab?

I was interested to hear the comment at the tail end of that story today, by someone from the FAA, that the MD80 had no "fail safe" for this particular failure... Left me wondering if I could think of any similar failsafe for any aircraft... Physical stab stops, I think.. If disconnected from the jackscrew, I guess other aircraft physically limit stab movement to lesser extremes than the MD80?... I have no idea...

J.O.,

You nailed it. Sadly, the guilty ones will undoubtedly blame all sorts of everything and everyone else... equally sadly, they're at least part right. That stuff doesn't happen in a vacuum!

[Mike Lavoy]

Mitch, I guess you're awake "prepping" for tomorrow night too!

[Mitch Cronin]

I try Mike... but nothing ever seems to work...

It's gonna be an interesting week.

[boestar]

I know that some jackscrew mechanisms have a cable arangement that will restrict the travel of the stab in the event of a failure of the jackscrew. Nothing like that on the MD80. Sad Story for sure.

B

[handyman]

Cpdude... I don't know the MD80, but I'm not aware of any large aircraft that won't allow one side or the other of a primary flight control to break free, or be controlled independantly of the other side, somehow when necessary... unfortunately, even on your 47's, the stab cannot be controlled by anyone once the jackscrew's threads are stripped clean. What would that QRH say about the stab when jammed? Does it not have a reference specifically for a jammed stab?

Mitch,

The B747-400 does have the shearouts that I described which will allow half the elevator or rudder to continue to function independant of the other jammed half. However, this is obviously only for a jam forward of the jackscrew. You are correct in saying "stab cannot be controlled by anyone once the jackscrew's threads are stripped clean".

As for a specific QRH for a jammed Stab. You are still instructed to force the jam.

Problem, you will never know where the jam is until it's too late.

so...cross your fingers

[Mitch Cronin]

Interesting Cpdude... Thanks..

From the link above, (Thanks Mike) with regard to that, here's what the NTSB recommended:

[emphasis added]

4.1 New Recommendations

As a result of the investigation of the Alaska Airlines flight 261 accident, the

National Transportation Safety Board makes the following recommendations to the

Federal Aviation Administration:

Issue a flight standards information bulletin directing air carriers to instruct

pilots that in the event of an inoperative or malfunctioning flight control

system, if the airplane is controllable they should complete only the

applicable checklist procedures and should not attempt any corrective

actions beyond those specified. In particular, in the event of an inoperative

or malfunctioning horizontal stabilizer trim control system, after a final

determination has been made in accordance with the applicable checklist

that both the primary and alternate trim systems are inoperative, neither the

primary nor the alternate trim motor should be activated, either by

engaging the autopilot or using any other trim control switch or handle.

Pilots should further be instructed that if checklist procedures are not

effective, they should land at the nearest suitable airport. (A-02-36)

I wonder what one could find about the FAA not following such recommendations?

[Mitch Cronin]

Interesting comment from one of the NTSB members:

"Had any of the managers, mechanics, inspectors, supervisors, or FAA overseers whose job it was to protect this mechanism done their job conscientiously, this accident cannot happen. The jackscrew is robust. Even at its wear limit condition, it is many times strong enough to carry out its function. And it does not wear quickly when cared for. It is a time-tested mainstay in the fleet, and one major carrier with a diligent approach to its maintenance has never seen one seriously wear, much less wear out. A whole herd of miscues was needed to allow it to fail. Virtually any system on an aircraft treated with the indifference shown to this mechanism will break, many with equally catastrophic effect.

Aircraft simply must be maintained, and maintained with care and at all cost."

Amen to that!

That last line is worth repeating... : "Aircraft simply must be maintained, and maintained with care and at all cost."

[handyman]

Interesting recommendations from the NTSB. Unfortunately, airlines don't issue QRH directions the manufactures do for legal reasons. So the recommendations should have gone to MD or Boeing now.

[boestar]

CPDude:

I believe what Mitch was getting at is that the overide you are talking about is the ELEVATOR breakout. The stab is controlled by the autopilot or by the thumb switches on the control column. An elevator jam can be overridden as long as the jam exists only in one half of the system (right or left). The elevator and stab trim systems are independant of each other and are considered different systems on the aircraft. Your explanation is correct but you are describing actions for the wrong system. If the stab jams and the motors will not overcome the jam, it is stuck and you cannot getaround it.

B

[handyman]

you are correct and I thought thats what I said

[Don Hudson]

Mitch;

I recall the Alaska story well. A sad, very large watershed-ish story for everyone at Alaska.

I ran across the following story in the National Post the other day which is perhaps of some interest although not related to the Alaska story or the main thrust of this thread.

Robert Milton's new Air Canada

Airline banking on foreign routes to boost revenue and may launch no-frills leisure carrier

Paul Vieira

Financial Post

Thursday, August 26, 2004

(entire story @ http://www.canada.com/national/nationalpos...6-fc2609f32887)

. . . . (story in part):

THE NEW CORPORATE STRUCTURE

When it exits bankruptcy protection, Air Canada will operate as a subsidiary of a new holding company, to be called ACE Aviation Holdings Inc. The business units formerly under Air Canada -- such as Aeroplan, the maintenance group (my bold edit) and Jazz, the regional feeder airline -- will now operate as limited partnerships under the ACE umbrella.

"The key driver in the formation of ACE is to push these businesses to run as true, profit-focused businesses, like they never have before under this mass called Air Canada," Mr. Milton says.

. . . .

"We've put [executive] teams in to drive profit in their businesses, as opposed to being businesses that knew they could always go to Air Canada to take care of them. They didn't have to worry about running it like a real profit-focused business. But now, we are going to hold them accountable and I am expecting big results."

© National Post 2004

Notwithstanding that this is just another newspaper article, (a genre which has demonstrated a notorious penchant for inaccuracy), I would like to take up the question surrounding the bolded font in the above article.

I understand how enterprises like Aeroplan and Jazz can (and must) operate "like a real profit-focused business", but I don't really understand how "the maintenance group" can operate under the pressures of being "held accountable" for "big results" by being run as "true, profit-focused businesses".

I know that excellent in-house work for other airlines has been and still is being done, and that kind of work would be expected to operate at a profit. But I don't see how an organization within an organization can "profit" from doing "business" inter-departmentally, even if strictly separate budgets are maintained. How does the "profit" show up on the larger organization's year-end reports? "Who's" profit is it? What is the meaning of "profit" when one department is "charged" by another and it shows up as "profit"? Its like all those trillions of inter-company cross-border (as in "nationless-round-the-world") financial exchanges showing up in the GNP of the originating country. What these transactions are, are transfers, not "business", and as such, they're an accounting fiction and so is, at least in my probably-limited view, "profit" made from such internal transactions.

To me, industry aircraft maintenance is part of the infrastructure of aviation. Its what you do as part of the business and as we all know its very costly to do it right. Air Canada's maintenance has been second to none in my 31+ years at AC and we take a back seat to no one. I guess the question for me is a structural one: Infrastructure, (like a country's highways) isn't expected to make a "profit" and in fact its a silly notion to even think of it that way, so I guess that's the trouble I'm having with placing the maintenance group under such demanding, business-oriented pressures. It seems that every conversation is defined in terms of business and not in terms of technical craft, or some other such architecture of dialogue. To me and likely to everyone who is involved in this end of the industry, maintenance is an inevitable and natural cost of flying which all passengers must accept and certainly share in. Its kind of like saying that safety organizations should be held accountable for their "profit" or "loss"...it just doesn't compute, does it?

There is mention of selling off these "profit-centers". Again, a familiar feature of business today, but further questions arise which I leave for now.

[deicer]

Infrastructure, (like a country's highways) isn't expected to make a "profit" and in fact its a silly notion to even think of it that way, so I guess that's the trouble I'm having with placing the maintenance group under such demanding, business-oriented pressures.

Don

I've always felt that it is the Americanisation of all things that is driving us to doom down that road.

I took this quote from you to raise the point that it is not only in the aviation industry, but all formerly publicly held industries.

Electricity, roads, water and sewage have all been sold off from public interest to make profit for the "masters". I thought that this infrastructure was supposed to be held publicly to support industry on a cost basis, and then profit was to be made moving forward from there.

Alas, it all comes back to the same thing.....

Greed

Iceman

[Guest ikfu]

Americanization vs what??? Look to Alitalia? They are virtually demanding that the EU airlines boost their fares to the point that is necessary for Alitalia to make money vis cost cutting in their own airline. This points out some of the major problems of the EU, and probably the major weaknesses that will see the demise of that union. You have the apparent inability to subsidize, yet have countries and airlines like Air France that will always find a work around.

[Mitch Cronin]

[...] I understand how enterprises like Aeroplan and Jazz can (and must) operate "like a real profit-focused business", but I don't really understand how "the maintenance group" can operate under the pressures of being "held accountable" for "big results" by being run as "true, profit-focused businesses".

I know that excellent in-house work for other airlines has been and still is being done, and that kind of work would be expected to operate at a profit. But I don't see how an organization within an organization can "profit" from doing "business" inter-departmentally, even if strictly separate budgets are maintained. How does the "profit" show up on the larger organization's year-end reports? "Who's" profit is it? What is the meaning of "profit" when one department is "charged" by another and it shows up as "profit"? Its like all those trillions of inter-company cross-border (as in "nationless-round-the-world") financial exchanges showing up in the GNP of the originating country. What these transactions are, are transfers, not "business", and as such, they're an accounting fiction and so is, at least in my probably-limited view, "profit" made from such internal transactions.

To me, industry aircraft maintenance is part of the infrastructure of aviation. Its what you do as part of the business and as we all know its very costly to do it right. [...]

Hi Don...

I share your uncertainty over the benefits of fictional profits between one arm of the same company and the other. I can't help but think that even the accounting of it all separately will have a cost that wouldn't otherwise exist. I recognize my limited knowledge of business must be a factor, but I'm sure that if my wife and I both counted our money separately, and we charged each other for services rendered on the others behalf, if nothing else, we'd have at least doubled the total effort in terms of billing and accounting. I've obviously missed the up-side?

Something I'm not sure everyone is aware of is that our maintenance has been split into two groups: Heavy maintenance (Air Canada Technical Services - ACTS) will be the arm that is looking to make a profit on their work for others as well as for AC... Line maintenance (known as Air Canada Maintenance - ACM) will remain as that necessarily costly infrastructure that continues to keep the aircraft moving on a day to day basis. I can't see how ACE could possibly profit by having ACM charge ACFltOps (?) for every can of oil poured, or tire changed... or whatever??

I don't believe there will ever be a time when AME's will be working "piece work" like the mechanics at an auto dealership. Something that comes to haunt those who feel that predictable time intervals can be expected and adhered to for a given task is simply that "stuff happens". Our A checks, for instance, have been a constant source of grief for folks who expect predictability. A part of any "check" of course is inspection... often we find snags while we conduct our inspections, which makes addressing that snag a necessary part of that "check". Not predictable. Surprisingly, there are still those who will attempt to say that an A check takes 'X' time... Sorry... it takes as long as it takes. Those "held accountable" for the time taken won't be those of us twisting the wrenches. Our primary goal isn't time, it's airworthiness and safety... time comes second.

Any attempts to change that fact that I've witnessed have usually backfired. Sometimes, with the more experienced among us, the backfire is instantaneous... the time taken for a given task will increase directly with the pressure applied. (extra time needs to be taken to ensure the distracting influence of that applied pressure hasn't caused anything to be missed) And sometimes, the backfire comes later, after errors are discovered and work needs to be redone... The costs of improperly done work in this industry can be unthinkable. Knowing that, as AME's all do, gives us the right - in fact, an obligation! - to tune out those who apply pressure.

Cheers,

Mitch

[boestar]

Saw this in a garage one time hanging on the wall htought it sort of applied.

Rates for Maintenance:

$80.00 /hr

If you watch: $100.00/hr

If you help: $120.00/hr

B

[boestar]

We hada 747-200 in for a check once (308 I believe). It came in with 80 outstanding items to be worked. It left with 144. Talk about unpredictable.

B

[Don Hudson]

Mitch;

Thanks for the response.

I didn't know that there were two divisions of AC maintenance. Now the comment in the paper makes more sense. I think the profit-goal is entirely reasonable when doing work for outside organizations. It was the internally-charged work, or the demand for accountability in terms of generating a profit by line-maintenance that seemed unreasonable. The way you explained it makes a lot of sense and that's very likely the approach taken by management. I suspect while there is always pressure to get the machine out, that pressure takes a back-seat to doing the job right and I believe that that approach is supported through all management levels right to the top. The devil is in the details on how this is done on a daily basis which is the reason your remarks in the latter half of your post are so important.

On the FDA (Flight Data Analysis, formerly FOQA) front, we are continuing to develop the relationship with ACTS in terms of maintenance event sets so that, along with the rich ACARS data, examination of system and part (valves, sensors etc) performance will be a routine preventative approach. The complexities of fielding this system are immense, (anyone here actually like solving networking problems?...if so, you're one sick puppy!! )

Mitch, or anyone here...This question has been asked before and I still have never seen a satisfactory answer, even from the manufacturers:

- What constitutes a heavy, or hard landing? (ok everyone, its open season - take yer shots!! )

There are two parameters available to measure vertical g loads...VRTG and VACC, the former sampled at 1/second and the latter sampled @ 4 times a second.

The airframe is certified for 2.5g's in the air, 2.0 if the slats/flaps are out, but I have yet to find information on the above question.

Its become important because now the question is no longer subjective; 'g' can be measured.

A landing which is generally felt to be 'firm' occurs around 1.5g's, and of course the spike is very quick. The 621 accident in 1972 recorded 16g's in the cabin and it was mathematically determined that the wings/engine mounts experienced, I believe, over 20g's.

The purpose in asking in the public forum is to see what others think demands a hard-landing check and what does not. When should it be written up so ACM can have a look and when is it just an experience and a story for telling around the hangar later?

This'll probably turn out like a discussion on V1 !!

[AME]

Don

I can't find anything yet either, but on the A340 the inspection for a hard and overweight landing is the same, so if a firm landing recorded 1.5G's would it not be reasonable to multiply the landing weight by 1.5 then compare it to the published max landing weight??

Brett

[Don Hudson]

Hi Brett;

Thanks...I think that line of thought needs some consideration. My initial thought is, there is no (legal, technical or SOP) way to relate the vertical acceleration with the published IVSI of 360fpm down at touchdown.

In our QRH (Quick Reference Handbook) for dealing with emergencies and abnormals, the overweight landing checklist requires a vertical descent rate of 360fpm or less on touchdown. There are no other requirements for this aspect of the landing. I've done one, (238000kg) and had the crew monitor the IVSI but we also had the maintenance page up on the ACARS and monitored the VACC...vertical acceleration. Mtc said if we could provide them with that number, they could determine if the airplane required an inspection. We did, and it didn't.

Sometimes when the 340/330 land, the unlocking of the bogie truck slams the airplane down so hard that I would have called the landing, had I done it, a hard one. Airbus however is the one doing the landing because their tilt-design of the bogies is employed to give the tail a few more feet of clearance on rotation and on landing. When the reverse is brought in (and the spoilers thus deploy), the bogies are depressurized and, with the spoilers killing all the lift, the airplane literally falls onto the front bogies resulting in a really firm "second" landing which is entirely beyond the crew's control. The technique sometimes employed is to either hold off the selection of reverse until the nosewheel is lowered sufficiently to provide very little distance for the forward bogies to go when they do unlock, or to hold the nosewheel off for a while and wait for the bogies to unlock on their own at a lower speed. Neither is reliable and I would defy any 340/330 pilot to come up with a consistent, predictable technique worth putting in the training syllabus. Some are better than others, but, like golf and tennis, no one is consistent and ET* has all the cards!! After the back bogey wheels are on the ground, everyone is along for the ride.

(Lest the above statement give rise to concerns on the part of non-Airbus crew or observers/passengers just reading this for knowledge, there is absolutely no hazard implied in the statement, "along for the ride"...Its an expression used when, 'in the moment', the airplane is settling onto the runway after initial touchdown and the airplane is 'doing its thing'. We're talking finesse here as opposed to controllability, which, in the latter case, is NEVER an issue! Ok?... )

*Etienne Tarnowski - THE Airbus guru, visionary, conceiver and designer of this brilliant generation of airplanes.