Tam A320 off runway in Sao Paulo
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invertedattitude
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Nope. As far as I know the landing distance calculations do not factor in thrust reversers.CAL wrote:sadly it seems almost anything can be MEL'D but dont the landing distance numbers for different airports not include the additional benefit of thrust reverse?
My condolences to all the families/friends of all involved in this tragedy.
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invertedattitude
- Rank 10
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No that's not possible because the thrust reversers are an upward and rearward motion on separate levers. Forward thrust levers of course go forward. Also given the surface of the runway and the rain the aircraft would have left the runway sideways almost immediately if that were the case and not gone off the end.invertedattitude wrote:Is it possible to reverse one engine, and thinking the #2 is reversed (moment of panic) and actually provide forward thrust to the #2 engine?
Would explain the left turning moment going off the runway.
It's amazing but not surprising the speculation over the actual cause that has gone on so far, and the behavior of the Brazilian government seems a bit dodgy. I think the best thing here is for a completely independant investigation. Good thing they sent the FDR and DVR to the states.
Ah, Rocky..."No that's not possible because the thrust reversers are an upward and rearward motion on separate levers. Forward thrust levers of course go forward. Also given the surface of the runway and the rain the aircraft would have left the runway sideways almost immediately if that were the case and not gone off the end."
Wrong...Thrust reverser levers are throttles that also connect to the buckets/blocker-door/vanes...if the reverser was bolted shut (the proper procedure for an MEL'd reverser), selecting the reverse lever MAY allow the throttle to open, increasing thrust on the engine that has the duff reverser, but with the bucket U/S, your thrust would be normally forward. Therefore, selecting reverse might add forward thrust. On modern a/c, apart from pilot-required limitations, the computer limits the amount of thrust available due to speed, so at a high speed, more thrust is available than at a lower speed. This is not so on all a/c, may only apply to FADEC engines and I have no idea (but suspect) this is true on a 'Bus.
Reverse on one engine would cause a yawing moment that woulod cause the pilot some control difficulties, especially on a 'Bus where the engines are wing-mounted.
We have no idea at what point the reversers were selected, if at all.
All performance numbers are calculated using brakes only, not including reverse.
Wrong...Thrust reverser levers are throttles that also connect to the buckets/blocker-door/vanes...if the reverser was bolted shut (the proper procedure for an MEL'd reverser), selecting the reverse lever MAY allow the throttle to open, increasing thrust on the engine that has the duff reverser, but with the bucket U/S, your thrust would be normally forward. Therefore, selecting reverse might add forward thrust. On modern a/c, apart from pilot-required limitations, the computer limits the amount of thrust available due to speed, so at a high speed, more thrust is available than at a lower speed. This is not so on all a/c, may only apply to FADEC engines and I have no idea (but suspect) this is true on a 'Bus.
Reverse on one engine would cause a yawing moment that woulod cause the pilot some control difficulties, especially on a 'Bus where the engines are wing-mounted.
We have no idea at what point the reversers were selected, if at all.
All performance numbers are calculated using brakes only, not including reverse.
"What's it doing now?"
"Fly low and slow and throttle back in the turns."
"Fly low and slow and throttle back in the turns."
I could be wrong xsbank, but what I believe he is asking is if it's possible for the pilot to mistakingly believe he had selected reverse and then moved the thrust levers forward thinking he was applying reverse thrust. I don't think he knows the configuration of the thrust/reverse thrust levers and how it's impossible to have one against the other. What you're talking about is increasing thrust through the reverse levers without the blocker doors being extended, which is also impossible since the thrust will not increase without fully extended doors and getting the "reverse green".
If a plane is dispatched with a MEL'd reverser, it must be deactivated and mechanically inhibited from opening. You are right in that reversers are not counted for certification purposes but you can apply a factor for having them if you want to use the charts to figure out your landing distance on any given landing.
The MEL procedure with a reverser locked out is for the crew to raise both reverse levers and apply max reverse on both one and two as if it were a normal two reverser landing.
In the case where the poster asks if having one engine producing full forward thrust and the other full reverse, you will depart the runway almost immediately even in dry conditions but especially in wet.
Anything else you want to disagree with?
If a plane is dispatched with a MEL'd reverser, it must be deactivated and mechanically inhibited from opening. You are right in that reversers are not counted for certification purposes but you can apply a factor for having them if you want to use the charts to figure out your landing distance on any given landing.
The MEL procedure with a reverser locked out is for the crew to raise both reverse levers and apply max reverse on both one and two as if it were a normal two reverser landing.
In the case where the poster asks if having one engine producing full forward thrust and the other full reverse, you will depart the runway almost immediately even in dry conditions but especially in wet.
Anything else you want to disagree with?
I wasn't sure so I had to double check, but looks to me from this pic as if the 320 has a setup that uses a forward thrust lever as control for reverse by going aft of a detent. Compared to the boeing style I believe Rockie is talking about.
Maybe I'm wrong, but here is the pic.
http://www.airliners.net/open.file?id=0 ... 544&size=L
If this is the case. If the doors are bolted shut and the pilot accidentally pulled the inop throttle back too to aid in slowing down I believe it would be possible to have forward thrust applied to that engine. I don't know what it would take to deactivate the fuel control to the inop reverse engine only when the throttle is aft of that detent, but it sounds like a l lot of programming, compared to just not using it. But who knows its all speculation
BTD
Maybe I'm wrong, but here is the pic.
http://www.airliners.net/open.file?id=0 ... 544&size=L
If this is the case. If the doors are bolted shut and the pilot accidentally pulled the inop throttle back too to aid in slowing down I believe it would be possible to have forward thrust applied to that engine. I don't know what it would take to deactivate the fuel control to the inop reverse engine only when the throttle is aft of that detent, but it sounds like a l lot of programming, compared to just not using it. But who knows its all speculation
BTD
Some engine/TR configurations DO allow increased thrust with the activation of the TR's even if the TR's ARE pinned.
This normally applies to cascading TR's that require engine bleed for deployment. The RPM only increases to make the minimum service bleed requirements. Normally, this is a marginal increase (1-3%N2) but a forward thrust increase none the less.
This normally applies to cascading TR's that require engine bleed for deployment. The RPM only increases to make the minimum service bleed requirements. Normally, this is a marginal increase (1-3%N2) but a forward thrust increase none the less.
There are two small finger lifts mounted on the forward side of the thrust levers. When they are lifted to the detent the FADEC commands engine thrust to idle until blocker door deployment is completed. The thrust levers actually move backward from the forward idle detent into the reverse range but that can only happen by lifting on the reverse levers (or switches if you prefer) on the front of the thrust levers. The thrust levers can then be moved further aft throughout the reverse range but the thrust won't increase unless the FADEC senses full deployment of the blocker doors. In the original question I think the poster was thinking the pilot selected reverse somehow and then moved the thrust levers forward to provide the thrust.
The blocker doors only reroute the low pressure fan air. In reverse thrust the engine core (hot section) is still producing forward thrust but the low pressure air (cold) that is deflected is much stronger resulting in a net reverse thrust.
In the Boeing products once the thrust levers reach the reverse stop that's as far back as they can go. The reverse levers are mounted on the front in the same place as Airbus but they are much bigger. There is a mechanical lockout that prevents the reverse levers from being pulled to the first detent unless the main thrust levers are at the idle stop. And there is another mechanical lockout that prevents the reverse levers from being further raised until it's respective engine has complete reverser deployment.
In either aircraft it is not possible for the pilot to select reverse thrust while airborne, although it has happened through some kind of fault.
The blocker doors only reroute the low pressure fan air. In reverse thrust the engine core (hot section) is still producing forward thrust but the low pressure air (cold) that is deflected is much stronger resulting in a net reverse thrust.
In the Boeing products once the thrust levers reach the reverse stop that's as far back as they can go. The reverse levers are mounted on the front in the same place as Airbus but they are much bigger. There is a mechanical lockout that prevents the reverse levers from being pulled to the first detent unless the main thrust levers are at the idle stop. And there is another mechanical lockout that prevents the reverse levers from being further raised until it's respective engine has complete reverser deployment.
In either aircraft it is not possible for the pilot to select reverse thrust while airborne, although it has happened through some kind of fault.
Yeah, the switches were the detents I meant. All that makes sense. My origional thought was that the poster was asking "if the pilot pulled both throttles into reverse would the one with inop reversers provide forward thrust due to the doors not opening."
Probably thinking along the lines of like a 737-200 with no FADEC. In a panic grabbed both reversers.
Oh well, it would be best to get him to clear it up, and it doesn't make a difference to the accident at this point.
Sad accident.
BTD
Probably thinking along the lines of like a 737-200 with no FADEC. In a panic grabbed both reversers.
Oh well, it would be best to get him to clear it up, and it doesn't make a difference to the accident at this point.
Sad accident.
BTD
NTSB Identification: LAX02FA266.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Scheduled 14 CFR Part 121: Air Carrier operation of AMERICA WEST AIRLINES (D.B.A. America West Airlines)
Accident occurred Wednesday, August 28, 2002 in Phoenix, AZ
Probable Cause Approval Date: 9/13/2005
Aircraft: Airbus Industrie A320-231, registration: N635AW
Injuries: 1 Serious, 9 Minor, 149 Uninjured.
After an asymmetrical deployment of the thrust reversers during landing rollout deceleration, the captain failed to maintain directional control of the airplane and it veered off the runway, collapsing the nose gear and damaging the forward fuselage. Several days before the flight the #1 thrust reverser had been rendered inoperative and mechanically locked in the stowed position by maintenance personnel. In accordance with approved minimum equipment list (MEL) procedures, the airplane was allowed to continue in service with a conspicuous placard noting the inoperative status of the #1 reverser placed next to the engine's thrust lever. When this crew picked up the airplane at the departure airport, the inbound crew briefed the captain on the status of the #1 thrust reverser. The captain was the flying pilot for this leg of the flight and the airplane touched down on the centerline of the runway about 1,200 feet beyond its threshold. The captain moved both thrust levers into the reverse position and the airplane began yawing right. In an effort at maintaining directional control, the captain then moved the #1 thrust lever out of reverse and inadvertently moved it to the Take-Off/Go-Around (TOGA) position, while leaving the #2 thrust lever in the full reverse position. The thrust asymmetry created by the left engine at TOGA power with the right engine in full reverse greatly increased the right yaw forces, and they were not adequately compensated for by the crew's application of rudder and brake inputs. Upon veering off the side of the runway onto the dirt infield, the nose gear strut collapsed. The airplane slid to a stop in a nose down pitch attitude, about 7,650 feet from the threshold. There was no fire. Company procedures required the flying pilot (the captain) to give an approach and landing briefing to the nonflying pilot (first officer). The captain did not brief the first officer regarding the thrust reverser's MEL'd status, nor was he specifically required to do so by the company operations manual. Also, the first officer did not remind the captain of its status, nor was there a specific requirement to do so. The operations manual did state that the approach briefing should include, among other things, "the landing flap setting...target airspeed...autobrake level (if desired) consistent with runway length, desired stopping distance, and any special problems." The airline's crew resource management procedures tasked the nonflying pilot to be supportive of the flying pilot and backup his performance if pertinent items were omitted from the approach briefing. The maintenance, repair history, and functionality of various components associated with the airplane's directional control systems were evaluated, including the brake system, the nose landing gear strut and wheels, the brakes, the antiskid system, the thrust levers and reversers, and the throttle control unit. No discrepancies were found regarding these components.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The captain's failure to maintain directional control and his inadvertent application of asymmetrical engine thrust while attempting to move the #1 thrust lever out of reverse. A factor in the accident was the crew's inadequate coordination and crew resource management.
Full narrative available
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Scheduled 14 CFR Part 121: Air Carrier operation of AMERICA WEST AIRLINES (D.B.A. America West Airlines)
Accident occurred Wednesday, August 28, 2002 in Phoenix, AZ
Probable Cause Approval Date: 9/13/2005
Aircraft: Airbus Industrie A320-231, registration: N635AW
Injuries: 1 Serious, 9 Minor, 149 Uninjured.
After an asymmetrical deployment of the thrust reversers during landing rollout deceleration, the captain failed to maintain directional control of the airplane and it veered off the runway, collapsing the nose gear and damaging the forward fuselage. Several days before the flight the #1 thrust reverser had been rendered inoperative and mechanically locked in the stowed position by maintenance personnel. In accordance with approved minimum equipment list (MEL) procedures, the airplane was allowed to continue in service with a conspicuous placard noting the inoperative status of the #1 reverser placed next to the engine's thrust lever. When this crew picked up the airplane at the departure airport, the inbound crew briefed the captain on the status of the #1 thrust reverser. The captain was the flying pilot for this leg of the flight and the airplane touched down on the centerline of the runway about 1,200 feet beyond its threshold. The captain moved both thrust levers into the reverse position and the airplane began yawing right. In an effort at maintaining directional control, the captain then moved the #1 thrust lever out of reverse and inadvertently moved it to the Take-Off/Go-Around (TOGA) position, while leaving the #2 thrust lever in the full reverse position. The thrust asymmetry created by the left engine at TOGA power with the right engine in full reverse greatly increased the right yaw forces, and they were not adequately compensated for by the crew's application of rudder and brake inputs. Upon veering off the side of the runway onto the dirt infield, the nose gear strut collapsed. The airplane slid to a stop in a nose down pitch attitude, about 7,650 feet from the threshold. There was no fire. Company procedures required the flying pilot (the captain) to give an approach and landing briefing to the nonflying pilot (first officer). The captain did not brief the first officer regarding the thrust reverser's MEL'd status, nor was he specifically required to do so by the company operations manual. Also, the first officer did not remind the captain of its status, nor was there a specific requirement to do so. The operations manual did state that the approach briefing should include, among other things, "the landing flap setting...target airspeed...autobrake level (if desired) consistent with runway length, desired stopping distance, and any special problems." The airline's crew resource management procedures tasked the nonflying pilot to be supportive of the flying pilot and backup his performance if pertinent items were omitted from the approach briefing. The maintenance, repair history, and functionality of various components associated with the airplane's directional control systems were evaluated, including the brake system, the nose landing gear strut and wheels, the brakes, the antiskid system, the thrust levers and reversers, and the throttle control unit. No discrepancies were found regarding these components.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The captain's failure to maintain directional control and his inadvertent application of asymmetrical engine thrust while attempting to move the #1 thrust lever out of reverse. A factor in the accident was the crew's inadequate coordination and crew resource management.
Full narrative available
"What's it doing now?"
"Fly low and slow and throttle back in the turns."
"Fly low and slow and throttle back in the turns."
