segunda-feira, 19 de setembro de 2016
From FlightSafety Fundation
Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's exhaust so that the thrust produced is directed forward this acts against the forward travel of the aircraft, providing deceleration. Thrust reversers are used by many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. Reverse thrust is typically applied immediately after touchdown, often along with spoilers, to improve deceleration early in the landing roll when residual aerodynamic lift and high speed limit the effectiveness of the friction brakes located on the gear. When thrust is reversed, passengers will hear a sudden increase in engine noise, particularly seated just forward of the engines.
A potência reversa, também chamada de empuxo reverso, é o desvio temporário do ar de exaustão do motor de uma aeronave tal que o impulso produzido é direcionado para frente; isto age contra o deslocamento da aeronave, proporcionando desaceleração. As potências dos reversores são usadas por muitos aviões à jato para ajudar a desacelerar exatamente após o toque no solo, reduzindo o desgaste nos freios e permitindo encurtar distâncias de pouso. O empuxo reverso é tipicamente aplicado imediatamente após o toque da roda do nariz no solo, frequentemente acompanhado de [abertura] dos spoilers, para melhorar a desaceleração no início da rolagem do pouso quando a força residual de sustentação aerodinâmica [para cima] e a alta velocidade limitam a eficácia de fricção dos freios localizados no trem de pouso. Quando o impulso é invertido, passageiros ouvirão um súbito aumento no ruído do motor, particularmente aqueles sentados à frente dos motores.
Thrust reverser provide a deceleration force that is independent of runway condition.
Thrust-reverser efficiency is higher at high airspeed.
Therefore, thrust reversers must be selected as early as possible after touchdown.
Thrust reverser should be returned to reverse idle at low airspeed to prevent engine stall or foreign object damage and stowed at taxi speed.
Nevertheless, maximum reverse thrust can be maintained to a complete stop in an emergency.
Potência reversora fornece uma força de desaceleração que é independente da condição de pista.
A eficiência da potência reversora é maior em velocidade alta.
Portanto, [os gatilhos] dos reversores devem ser selecionados tão cedo quanto possível após o toque da roda do nariz no solo. Os [gatilhos] de potência dos reversores devem ser retornados para marcha-lenta (idle) em velocidade baixa para evitar que o motor “afogue” ou seja danificado por [ingestão] de objetos estranhos e parado [o funcionamento] em velocidade de táxi.
Não obstante, a potência máxima reversa pode ser mantida até uma parada completa em uma emergência.
Factos Affecting Braking
The following factors have affected braking in runway excursions or runway overruns:
- Failure to arm ground spoilers, with thrust reversers deactivated (e. g., reliance on a thrust-reverser signal for ground-spoilers extension, as applicable).
- Failure to use any braking devices (i. e., reliance on the incorrect technique of maintaining a nose-high attitude after touchdown to achieve aerodynamic braking.
The nose-whell should be lowered onto the runway as soon as possible to increase weight-on-wheels and activate aircraft systems associated with the nose-landing-gear squat switches.
- Asymmetric thrust (i. e., one engine above idle in forward thrust or one engine failing to go into reverse thrust.
- Brake unit inoperative (e. g., reported as a "cold brake", i.e., a brake whose temperature is lower, by a specified amount, than the other brakes on the same landing gear.
- Spongy pedals (air in the hydraulic wheel-braking system.
- Anti-skid tachometer malfunction.
- Failure to adequately recover from loss of the normal braking system.
- Late selection of thrust reversers.
- No takeover or late takeover from autobrakes, when required.
- No switching or late switching from normal braking to alternate braking or to emergency braking in response to abnormal braking.
- Crosswind landing and incorrect braking technique.
sexta-feira, 9 de setembro de 2016
September 8, 2016
Contact: Laura Brown
In light of recent incidents and concerns raised by Samsung about its Galaxy Note 7 devices, the Federal Aviation Administration strongly advises passengers not to turn on or charge these devices on board aircraft and not to stow them in any checked baggage.
Replace Current Note7 with New One
on September 02, 2016
Samsung is committed to producing the highest quality products and we take every incident report from our valued customers very seriously. In response to recently reported cases of the new Galaxy Note7, we conducted a thorough investigation and found a battery cell issue.
To date (as of September 1) there have been 35 cases that have been reported globally and we are currently conducting a thorough inspection with our suppliers to identify possible affected batteries in the market. However, because our customers’ safety is an absolute priority at Samsung, we have stopped sales of the Galaxy Note7.
For customers who already have Galaxy Note7 devices, we will voluntarily replace their current device with a new one over the coming weeks.
We acknowledge the inconvenience this may cause in the market but this is to ensure that Samsung continues to deliver the highest quality products to our customers. We are working closely with our partners to ensure the replacement experience is as convenient and efficient as possible.
terça-feira, 6 de setembro de 2016
As the flight neared Dubai, the crew received the automatic terminal information service (ATIS) Information Zulu, which included a windshear warning for all runways.
The Aircraft was configured for landing with the flaps set to 30, and approach speed selected of 152 knots (VREF + 5) indicated airspeed (IAS) The Aircraft was vectored for an area navigation (RNAV/GNSS) approach to runway 12L. Air traffic control cleared the flight to land, with the wind reported to be from 340 degrees at 11 knots, and to vacate the runway via taxiway Mike 9.
During the approach, at 0836:00, with the autothrottle system in SPEED mode, as the Aircraft descended through a radio altitude (RA) of 1,100 feet, at 152 knots IAS, the wind direction started to change from a headwind component of 8 knots to a tailwind component. The autopilot was disengaged at approximately 920 feet RA and the approach continued with the autothrottle connected. As the Aircraft descended through 700 feet RA at 0836:22, and at 154 knots IAS, it was subjected to a tailwind component which gradually increased to a maximum of 16 knots.
At 0837:07, 159 knots IAS, 35 feet RA, the PF started to flare the Aircraft. The autothrottle mode transitioned to IDLE and both thrust levers were moving towards the idle position. At 0837:12, 160 knots IAS, and 5 feet RA, five seconds before touchdown, the wind direction again started to change to a headwind.
As recorded by the Aircraft flight data recorder, the weight-on-wheels sensors indicated that the right main landing gear touched down at 0837:17, approximately 1,100 meters from the runway 12L threshold at 162 knots IAS, followed three seconds later by the left main landing gear. The nose landing gear remained in the air.
At 0837:19, the Aircraft runway awareness advisory system (RAAS) aural message “LONG LANDING, LONG LANDING” was annunciated.
At 0837:23, the Aircraft became airborne in an attempt to go-around and was subjected to a headwind component until impact. At 0837:27, the flap lever was moved to the 20 position. Two seconds later the landing gear lever was selected to the UP position. Subsequently, the landing gear unlocked and began to retract.
At 0837:28, the air traffic control tower issued a clearance to continue straight ahead and climb to 4,000 feet. The clearance was read back correctly.
The Aircraft reached a maximum height of approximately 85 feet RA at 134 knots IAS, with the landing gear in transit to the retracted position. The Aircraft then began to sink back onto the runway. Both crewmembers recalled seeing the IAS decreasing and the Copilot called out “Check speed.” At 0837:35, three seconds before impact with the runway, both thrust levers were moved from the idle position to full forward. The autothrottle transition from IDLE to THRUST mode. Approximately one second later, a ground proximity warning system (GPWS) aural warning of “DON’T SINK, DON’T SINK” was annunciated.
One second before impact, both engines started to respond to the thrust lever movement showing an increase in related parameters.
At 0837:38, the Aircraft aft fuselage impacted the runway abeam the November 7 intersection at 125 knots, with a nose-up pitch angle of 9.5 degrees, and at a rate of descent of 900 feet per minute. This was followed by the impact of the engines on the runway. The three landing gears were still in transit to the retracted position. As the Aircraft slid along the runway, the No.2 engine-pylon assembly separated from the right hand (RH) wing. From a runway camera recording, an intense fuel fed fire was observed to start in the area of the damaged No.2 engine-pylon wing attachment area. The Aircraft continued to slide along the runway on the lower fuselage, the outboard RH wing, and the No.1 engine. An incipient fire started on the underside of the No.1 engine.
The Aircraft came to rest adjacent to the Mike 13 taxiway at a magnetic heading of approximately 240 degrees. After the Aircraft came to rest, fire was emanating from the No. 2 engine, the damaged RH engine-pylon wing attachment area and from under the Aircraft fuselage. Approximately one minute after, the Commander transmitted a “MAYDAY” call and informed air traffic control that the Aircraft was being evacuated.