AA 777 loses 2L door at DFW in bizzare incident

[FWAAA]

Just out of curiosity...is there any chance this was a jetbridge malfunction?

I don't think so, as the jetbridge is not designed (nor capable) of preventing the plane from rolling backwards 200 feet from the parking spot. That's the job of brakes (primary) and wheel chocks (secondary).

Regardless of the wisdom of the auto park system, someone should always chock the wheels of an airplane. AA's lucky that nobody did a face plant on the apron.

 

[JFK Fleet Service]

I seem to remember chocking aircraft,specifically the double chocking of RON aircraft being a hot button issue after that 763 went free wheeling in LAX a few years back.

Has AA once again drifted away from their own policies and procedures?

 

[Mach85ER]

Absolutely...
After aircraft arrival, engines shut down and hydraulics off, parking brake alone would should have kept the aircraft stopped.

Believe it or not, humans are responsible from time to time.

Hopeful,

I edited your post to more accurately reflect actual operations. This isn't the first roll-back with a widebody. The other one did not result in any damage and was rumoured to a have a brake problem resulting in a loss of pressure.

If it was a failure to set the brake on arrival, it will be documented on the Flight Recorder, which is easily downloadable.

Agree that humans make mistakes. This also includes mistakes made by ignoring prudent aircraft handling practices in place in the 100+ years since wheels were first installed on airplanes.

 

[jetmechjer]

12 yes thats right 12 brakes and 3 seperate hydraulic systems and accumulators do not all fail at one time. Aircraft went to hangar where they tested everything and found no faults. I anxiously await the flight recorder results as it was taken from the aircraft immediately. Maintenance was ordered from headquarters to change the parking valve for no reason what so ever! Yes we are losing money so lets change good parts to cover for the Sky Gods!!! I am sure the flight department will block maintnenace from getting the flight recorder results but let just stand by and hope to hear............the rest of the story!!

 

[Mach85ER]

jetmechjer,

Since this is a public internet board, the uniformed might think your screename might actually reflect some knowledge on your part of aircraft systems. unfortunately, you have demonstrated a near total ignorance of aircraft maintenance issues and a lack of common sense in slandering the AA pilots involved in this door incident before all of the facts are known.

With your attitude and knowledge, it would seem likely that you might be a chubby 12 year old kid full of keyboard courage. Since we have a quandry regarding your credentials, if you are a AA mechanic, it should be very easy to answer a few questions:

12 yes thats right 12 brakes and 3 seperate hydraulic systems and accumulators do not all fail at one time.

Please clarify: Are there 12 separate and independant hydraulic lines that with one or more line failures or leaks, the remaining brakes would stay pressurized, or would they all depressurize with a leak?

You mentioned 3 hydraulic systems. Which ones provide brake pressure?

Aircraft went to hangar where they tested everything and found no faults. I anxiously await the flight recorder results as it was taken from the aircraft immediately. Maintenance was ordered from headquarters to change the parking valve for no reason what so ever! Yes we are losing money so lets change good parts to cover for the Sky Gods!!!

Interesting. I might lean towards slamming the pilots if I haven't had a career of reading balancing write ups of "ops check normal, could not duplicate, ok to return to service" right before "dupicating" the problem on the next leg. :blink:

I am sure the flight department will block maintnenace from getting the flight recorder results but let just stand by and hope to hear............the rest of the story!!

I am interested in reading about the exact cause also, from all sources. If you're AA MX, you should have easy access to other private information that shouldn't be shared in a public forum. Try finding the prelim account written by the Flight Dept pilot. Call him, he'd probably talk to you if you're AA. Better yet, read some of the history of the aircraft. If you're are capable of that, it might be interesting to read. I will patiently wait for your apology to the AA pilots involved. If you can't check that info, it's probably not to late to get into a summer camp.

I'll wait awhile before throwing stones at the pilots, they may or may not have been a factor. From what I've learned, it would seem there is more to the story.

Sincerely,
Your humble SkyGod

 

[Hopeful]

Hopeful,

I edited your post to more accurately reflect actual operations. This isn't the first roll-back with a widebody. The other one did not result in any damage and was rumoured to a have a brake problem resulting in a loss of pressure.

If it was a failure to set the brake on arrival, it will be documented on the Flight Recorder, which is easily downloadable.

Agree that humans make mistakes. This also includes mistakes made by ignoring prudent aircraft handling practices in place in the 100+ years since wheels were first installed on airplanes.

I'm not ruling out parking brake failure...(and not to try and educate you, but I know you know brakes can operate normally during taxi AND can also have a PARKING brake failure either due to a valve, or accumulator issues, etc)
So the pilot stopped normally, applied the parking brake...I assume he checked brake pressure. In his/her defense, there may have been a "bleed down" condition AFTER he/she left the cockpit.
I have done many a brake bleed down check at the gate and can tell you that the depletion of brake accumulator pressure occurred over 5 minutes in some cases and as much as 20 minutes in other cases.

So if we are talking a parking brake failure in less than 5 minutes after a/c arrival, it might have not been the accumulator. An accumulator does not drop pressure that fast unless it outright ruptured. I have never seen that in my near 40 years as a mechanic. The valve could be the culprit.
When you park your brakes, do you look at the gauge? I do when I taxi....

Having added my $.02, I can only guess as I was not there and in no way involved.




What I am saying is that an unchocked aircraft would not normally move if the parking brake was on...and yes ONLY if it were operating normally.

 

[Mach85ER]

Hopeful,

Thanks for returning some sanity to this discussion without throwing stones.

Nothing in the typical checklist says to check the pressure after parking. I thinks it's been that way on the 5 AA planes I've flown.

There is also nothing written for checking the accumulator pressure while taxing in.
Why not? I dunno. My guess is that it is redundant because there should be multiple hydraulic and anti-skid lights and warnings with a pressure dump. I check the acc gauge approaching the gate mainly for ancestor worship. The 727 Captains did it, so I learned the habit from them. I'm not sure the 777 even has a gauge that isn't buried on a screen display.

After parking, there isn't a pressure check, just a hydraulic quantity check, which is just a check to request a refill if neccessary.

Who knows about the valve. With the newer planes, a line of software code could be the culprit, and we both know that those are more difficult to find an d result in the "could not duplicate" entries until boeing finally figures it out.

 

[Hopeful]

Hopeful,

Thanks for returning some sanity to this discussion without throwing stones.

Nothing in the typical checklist says to check the pressure after parking. I thinks it's been that way on the 5 AA planes I've flown.

There is also nothing written for checking the accumulator pressure while taxing in.
Why not? I dunno. My guess is that it is redundant because there should be multiple hydraulic and anti-skid lights and warnings with a pressure dump. I check the acc gauge approaching the gate mainly for ancestor worship. The 727 Captains did it, so I learned the habit from them. I'm not sure the 777 even has a gauge that isn't buried on a screen display.

After parking, there isn't a pressure check, just a hydraulic quantity check, which is just a check to request a refill if neccessary.

Who knows about the valve. With the newer planes, a line of software code could be the culprit, and we both know that those are more difficult to find an d result in the "could not duplicate" entries until boeing finally figures it out.

Hence, CHOCK THE AIRCRAFT!

 

[eolesen]

Hence, CHOCK THE AIRCRAFT!

Yep. There's a reason they cover that on day one of both jetbridge and FSC training....

Only time I've seen an aircraft jump a chock is during an engine runup...

 

[BoeingBoy]

Only time I've seen an aircraft jump a chock is during an engine runup...

Not jump a chock, but I've seen aircraft weather-vane out of the chocks. US chocks the noes in normal through stops. After a couple of incidents where the aircraft weather-vaned out of the chocks, they changed that to chocking the mains in windy conditions.

Jim

 

[Hopeful]

Yep. There's a reason they cover that on day one of both jetbridge and FSC training....

Only time I've seen an aircraft jump a chock is during an engine runup...

..... and the engines were most likely at takeoff power to jump them....
I've seen it as well, max power assurance checks of both engines...and then the "jump".....

The chock is the last best defense against human error and mechanical malfunction.

 

[upsilon]

I surprised no one has posted this:

http://aviationblog.dallasnews.com/archives/2010/06/american-explains-about-that-d.html

What are your comments?

 

[Mach85ER]

I surprised no one has posted this:

What are your comments?

I for one didn't post it because it was internal communication and not an official report. I alluded to it as well as some later history of the aircraft that directly conflicts with jetmech's venomous post blaiming the "SkyGod's". if he/she is AA the information was easily found.

Terry Maxon probably won't give up a source of AA documents and photo's if pressed. An internet chatboard will give up a posters ISP address in a NY second if pressed.

Any "New Age" comes with new ways to get fired. :blink:

 

[Ralph]

Terry Maxon probably won't give up a source of AA documents and photo's if pressed. An internet chatboard will give up a posters ISP address in a NY second if pressed.

Any "New Age" comes with new ways to get fired. :blink:

Just FYI, everyone. I doubt we would give up a poster's identity (to the extent we even know who you are) unless under court order, but it's one of the reasons why we have the following board rule...

3. NO material from other sites without WRITTEN permission of the author/publisher-FURTHERMORE letters, emails and other messages intended for an individual or limited group, copying and pasting of emails intended for specific labor groups is not permitted at ANY time.

As a journalist, Terry Maxon has First Amendment protections against divulging sources. This right is not established for Internet bulletin boards. Mostly because of the gray area that we are not divulging internal memos, you are. We are just providing the electronic medium.

 

[Hopeful]

I surprised no one has posted this:

http://aviationblog.dallasnews.com/archives/2010/06/american-explains-about-that-d.html

What are your comments?

Ok,,,that explains it...parking brake failed...And problem recognized quite quickly.

Hence..........NO CHOCKS!

Human error!