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American 763 takeoff incident, ORD

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American 763 takeoff incident, ORD

Old 3rd Nov 2016, 20:55
  #141 (permalink)  
 
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Designed by Mr Murphy, no doubt.

I stand to be corrected, but I can't see something like that ever getting certificated.
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Old 3rd Nov 2016, 21:07
  #142 (permalink)  
 
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Listening to ATC recordings link provided by Airbubba, T/O clearance issued at 01:05 and stopping on rwy call at 01:49 would suggest a/c was 44 seconds in t/o roll when event occurred. I would have thought this was in the very nick of time, just a few seconds before V1. These guys were really switched on.
Another important factor in the outcome must be the fact that somehow, no fragments penetrated the cabin.
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Old 3rd Nov 2016, 21:57
  #143 (permalink)  
 
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Originally Posted by triploss View Post
At least some 767-300s have cabin crew stationed by the overwing exits. I know that's the case on ANA (toilet in front of the first overwing, with 2 CC seats on the back wall/by the first door, divider between the exits, normal passenger seat aft of the second exit). Not too sure about the AA 763, seatmaps suggest this isn't the case there.
AA's 763 have two passenger-operated doors each side over the wing, and a crew-operated door front and rear on each side of the wing. On the AA 763 seat rows 20 and 21 are the exit rows and the passenger sitting there may have to operate the door. I have sat in those seats many times.

The nearest crew are on jump seats that fold out into the aisle at row 17 (crew rest seats). They might be able to get to the wing exit in front of the seated passenger, but might also have a hard time manoeuvring the door without dropping it (on the pax in the seat!).
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Old 3rd Nov 2016, 23:24
  #144 (permalink)  
 
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Decision?

Originally Posted by rcsa
...on a variety of African carriers ...I get a comprehensive briefing, asking if I am prepared to open the door if necessary, explaining fire, smoke, debris problems, shown how the door works (pull this lever, hold here, twist and turn, it's quite heavy, are you comfortable with this?)
What if anything do they say about the decision to initiate? In particular, do they sternly advise you to await orders?

Last edited by archae86; 3rd Nov 2016 at 23:32. Reason: improve quoted context
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Old 3rd Nov 2016, 23:51
  #145 (permalink)  
 
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I believe those over wing exits are locked through an electric circuit and can only be opened once the flight deck (or cabin crew?) removes power to the lock, or power is disrupted (crash). So is it not part of the process that for the over wing exits to be opened the crew had to activate the de-lock device?
Emergency doors requiring a flight lock will automatically unlock depending on the aircraft state -- e.g., air/ground mode, throttle position, engine thrust, etc. -- without crew intervention.
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Old 4th Nov 2016, 01:29
  #146 (permalink)  
 
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Emergency doors requiring a flight lock
Why would you want a flight lock?

It's just another system to fail at an inopportune time in a survivable prang
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Old 4th Nov 2016, 01:48
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If your exit is of the non plug type like a jumbo upper deck for instance then the flight lock stops the handle being moved with weight off wheels. Just a basic solenoid that engages in the handle and usually fails in a way so as not to inhibit door opening. Can't vouch for the 767.
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Old 4th Nov 2016, 01:50
  #148 (permalink)  
 
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Why would you want a flight lock?
Not all emergency doors are of plug-type. It would be disastrous if someone opened a non-plug door mid-flight, so fail-safe locks are required to secure them.

FAR 23.807 - Emergency Exits
(d)(2) A means must be provided to lock each emergency exit and to safeguard against its opening in flight, either inadvertently by persons or as a result of mechanical failure. In addition, a means for direct visual inspection of the locking mechanism must be provided to determine that each emergency exit for which the initial opening movement is outward is fully locked.
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Old 4th Nov 2016, 15:20
  #149 (permalink)  
 
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Recently (twice last weekend, Harare to Nairobi, Nairobi to Lagos), on Kenya Airways 'When you hear the command 'evacuate' - then check outside to make sure there is no fire and it's safe to go. If if it isn't, try to stop other people opening the door'. Briefing delivered carefully, clearly and with eye contact.

Not bad, in fact. Not bad at all.
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Old 4th Nov 2016, 16:25
  #150 (permalink)  
 
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And now for something entirely different

It seems to me that the essence of the problem is speedy suppression of fire emanating from ruptured tanks. No fire - no problem with evacuation.
So, when building runways why not have a couple of well-indicated pads spaced out at each end under which are truly massive supression foam generators which can be triggered from the tower as to half a pad or a full pad of upwardly directed foam spray. They are always part of the runway, just a different colour
Aircraft in trouble aims for pads: commander calls tower for jets: fire suppressed: measured evac: possible hull saved: pads paid for many times over.
Or is it too simple an idea, like cheap external cameras that someone has to be paid millions to come up with!
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Old 4th Nov 2016, 16:29
  #151 (permalink)  
 
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But do American B-763 overwing doors have a flight lock?

I know there are some unusual door configs on 767's and some B-767-300's don't have overwing exits at all. Obviously N345AN has the overwing exits.

Also, some 737's have the flight lock on the wing exits, others do not, is that right?
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Old 4th Nov 2016, 17:36
  #152 (permalink)  
 
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NTSB Update

To view the graphics goto:
http://www.ntsb.gov/news/press-relea...r20161104.aspx
NTSB Press Release
National Transportation Safety Board Office of Public Affairs

NTSB Issues Investigative Update on Uncontained Engine Failure Accident Involving a Wide Body Jetliner
11/4/2016

As part of its ongoing investigation of an Oct. 28, 2016, uncontained engine failure on American Airlines flight 383, the National Transportation Safety Board issued an investigative update Friday.

The uncontained failure of a GE CF6-80C2B6 engine occurred on a Boeing 767-300 (N345AN) during the take-off roll at Chicago O'Hare International Airport. An emergency evacuation of the 161 passengers and nine crewmembers onboard was conducted.

Initial findings include the following:

According to witness statements from airport personnel, video evidence, flight data recorder (FDR) data and GPS data, the accident flight started its takeoff roll on runway 28R at the intersection with taxiway N5.

The airplane experienced an uncontained failure of the right engine about 6,550 feet from runway 28R threshold, and came to a full stop about 9,225 feet from runway 28R threshold.

Airport overview with disk fragment locations
Preliminary FDR data show that the right engine failure occurred at an airspeed of about 128 knots with the engine operating at takeoff power.

Approximately two seconds after the engine failure, at an airspeed of about 134 knots, the left and right engine throttle lever angles decreased rapidly. Coincident with the throttle movement, brake pressure rose in a manner consistent with maximum autobrake application; the auto speedbrakes were extended.

The aircraft rapidly decelerated, coming to a stop about 25 seconds after the throttle reduction.

As a result of the uncontained engine failure, a fuel leak resulted in a pool fire under the right wing.

Airport Rescue and Fire Fighting personnel began applying foam within 2 minutes 51 seconds of being notified of the emergency.

The right engine stage 2 high pressure turbine disk fractured into at least 4 pieces (locations A, B, C, and D on figure). One piece went through the inboard section of the right wing, over the fuselage and into a UPS warehouse facility (location A).
Recovered stage 2 HPT disk pieces
Recovered stage 2 HPT disk pieces

The majority of the stage 2 disk was recovered and sent to the NTSB laboratory in Washington, DC for examination. One of the fractures exhibited features consistent with fatigue cracking initiating at an internal inclusion near the forward side of the hub’s inner bore.

Engine and wing debris were found in the area around the gouge mark on the runway.

Fatigue crack location on a disk fracture surface
Fatigue crack location on a disk fracture surface


3-D imaging of the damage to the right wing has been completed.

All members of the cabin crew has been interviewed.

The disk had 10,984 cycles and had a life limit of 15,000 cycles. Review of the engine maintenance and manufacturing records and processes are ongoing.

Daily progress meetings are being held and the final documentation and examination of the airplane and engine continues in Chicago; the on-scene team plans to finish work by this weekend.

NTSB Senior Air Safety Investigator Lorenda Ward, the Investigator-in-Charge, is leading a team with expertise in the areas of airworthiness, powerplants, structures, survival factors, maintenance records, flight recorders and metallurgy. The flight data recorder and the cockpit voice recorder were transported to the NTSB Recorder Laboratory where the information from each was downloaded.

Parties to the investigation include the Federal Aviation Administration, American Airlines, Allied Pilots Association, The Boeing Company, General Electric Engines, the Transport Workers Union of America and the Association of Professional Flight Attendants.

Ongoing metallurgical examinations of the disk will focus on detailed characterization of the inclusion and the fracture surfaces.

The accident docket, containing factual group reports and other investigation-related material, will be opened at a future date. Additional information will be released as warranted.
Related Press Releases
November 04, 2016
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Old 4th Nov 2016, 18:02
  #153 (permalink)  
 
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A few photos if aircraft damage:
The Engine Took Out A 767 ? AA Flight 383-Photos - Flying Lessons
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Old 4th Nov 2016, 18:27
  #154 (permalink)  
 
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The fractured pieces are typical of a gross defect even if a major piece was missing. The largest piece typically bounces off the runway (more spin than outward movement).

Very surprising after 50 years of commercial manufacture experience to have a metallugical defect escape of that size. Equally surprising that it wasn't detected during routine overhauls in the shop. After all the crack must have many engine cycles visible in the striations.

The only good news is that the combinations are very rare throughout the many years of service experience with all like engine models (GE, RR P&W)

Of course there is some question remaining about the pedigree of this manufacturing process and other parts made at the same time.

Let's see what airworthiness actions come out immediately
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Old 5th Nov 2016, 01:55
  #155 (permalink)  
 
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Originally Posted by vs69 View Post
If your exit is of the non plug type like a jumbo upper deck for instance then the flight lock stops the handle being moved with weight off wheels. Just a basic solenoid that engages in the handle and usually fails in a way so as not to inhibit door opening. Can't vouch for the 767.
Weight off wheels? Does that mean that in the event of failed gear/a belly landing, that the exits won't open? If so, that doesn't seem like a good idea.
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Old 5th Nov 2016, 07:12
  #156 (permalink)  
 
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Originally Posted by Airbubba View Post
But do American B-763 overwing doors have a flight lock?

I know there are some unusual door configs on 767's and some B-767-300's don't have overwing exits at all. Obviously N345AN has the overwing exits.

Also, some 737's have the flight lock on the wing exits, others do not, is that right?
The 738 locks & unlocks the overwing exits via engine throttle position.Classic 737s have no lock mechanism.
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Old 5th Nov 2016, 09:18
  #157 (permalink)  
 
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Jugofpropwash; From looking at the basic schematic in the manual it looks like air ground sense is the only deciding factor. But yes valid point!
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Old 5th Nov 2016, 13:12
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The applicable rule regarding emergency exits is FAR 25.783. I have attached the relevant excerpts from Advisory Circular 25.783-1A below. Two thoughts come to mind: first, the design and certification engineering folks are pretty thorough in their work. Ergo, they are not going to hand you an emergency exit that cannot be opened in an emergency, or one that depends solely on the pilots surviving long enough to retard the throttles. Second, anybody who thinks that regulators don't have a sense of humor need only read the second sentence in paragraph b. (1) below.

The 737 overwing exits at my operator require 3 of the 4 entry/service doors closed, at least one engine running, and air/ground logic is in the air or both throttles are advanced. If any of these conditions is not met, or if DC power fails, the overwing exits unlock.

AC 25.783 excerpt:

b. In addition, design precautions must be taken to minimize the possibility for a person to open a door intentionally during flight. If these precautions include the use of auxiliary devices, those devices and their controlling systems must be designed so that--

• no single failure will prevent more than one exit from being opened [§ 25.783(b)(1)]; and

• failures that would prevent opening of the exit after landing are improbable [§ 25.783(b)(2)].

(1) The intentional opening of a door by people on board while the airplane is in flight should be considered. This rule is intended to protect the airplane and passengers, but not necessarily the person who intentionally tries to open the door. Suitable design precautions should therefore be taken; however, the precautions should not compromise the ability to open an emergency exit in an emergency evacuation. In this context, single failures include hardware failures as well as maintenance and logical (e.g., software) errors. Note that certain maintenance or logical errors may have the potential to affect more than one door.

(2) The applicant should consider the following precautions:

(a) Doors in pressurized compartments. It should not normally be possible to open the door when the compartment differential pressure is above 2 psi. The ability to open the door will depend on the door operating mechanism and the handle design, location, and operating force. Operating forces in excess of 300 pounds should be considered sufficient to prevent the door from being opened. During approach, takeoff, and landing, when compartment differential pressure is lower, intentional opening may be possible; however, these phases are brief and all passengers are expected to be seated with seat belts fastened.

(b) Doors that cannot meet the guidance of paragraph 9b(2)(a) of this AC, and Doors in non-pressurized airplanes. The use of auxiliary devices (for example, a speed-activated or barometrically-activated means) to safeguard the door from opening should be considered. The need for such auxiliary devices should depend upon the consequences to the airplane and other occupants if the door is opened in flight.

(c) Auxiliary devices installed on emergency exits. The failure of an auxiliary device should normally result in an unsecured position of the device. Failures of the device that would prevent opening of the exit after landing should be improbable.
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Old 5th Nov 2016, 14:57
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Door Flight Locks

Just for info. On the B777 and B787 the door flight locks engage at or above IAS of 80knots and disengage at IAS below 80knots.
I think. It could be TAS or CAS I forget.
Not sure about B767.
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Old 5th Nov 2016, 17:57
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Originally Posted by Maxmotor View Post
The 738 locks & unlocks the overwing exits via engine throttle position.Classic 737s have no lock mechanism.
The 737-800 and -900 have outwards opening doors operated by a handle, the others have plug doors that must be removed from the frame inwards and are a plug-type door. So perhaps they don't need a lock, as the airframe is pressurised enough to make it impossible to remove them in flight?
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