A330/A340 机组训练手册 FCTM Flight Crew Training Manual(73)

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At certain weights and CG positions, it may not be possible to satisfy . target demands at VLS. Consequently, when obstacle clearance is assured, accelerate to a speed at which the . target can be satisifed.
TWO ENGINES INOPERATIVE LANDING (A343/A346) General
Operational requirements following a second engine failure are detailed in Volume 2 Part 2. Continued flight may be complicated by driftdown, lateral navigation requirements to ensure terrain clearance, fuel jettison to achieve desired performance and other factors.
It is recommended that weather at the selected ERA should permit visual flight on approach from at least 500 ft AGL to the runway. The primary consideration for approach, landing and go-around is one of control. Go-arounds in particular require careful planning, briefing and execution to ensure controllability margins are not compromised.
The nature of the failure also needs to be considered, particularly which combination of engines and associated hydraulic systems have been lost.
Loss Of One Engine On Each Wing
For the loss of any two engines from opposite wings, VLS on the MCDU and PFD is limited to VMCL (A343: 125 kt), (A346: 132 kt). The loss of engines 1 and 4 does not have a major effect on control, however without the green hydraulic system a manual landing gear extension is required and there is no retraction capability. Consequently a go-around is not possible after L/G extension and the aircraft is committed to land . Landing must be assured prior to L/G extension.

A330/A340 8.20.13 Operating Techniques
FCTM REV 1 (6 JUN 05)
Loss Of Two Engines On The Same Wing
Control of the aircraft is more complicated following the loss of two engines on a single wing. The critical factor is speed, which must not reduce below VMCL-2 (157 kt) until landing is assured. VLS displayed on the PFD will never be lower than VMCL-2. Speed reduction below VMCL-2 is permissible once landing is assured. L/G retraction is available in the event of a go-around, but failure to maintain VMCL-2 with TOGA thrust applied and an insufficient bank angle, will result in loss of directional control.
Approach
A “Commit Altitude” is established for any two engine approach. The equivalent height should never be below 500 ft AGL. It serves two purposes; to establish a decision point on approach from which a “land or go-around” decision can be made, and because it is well above the Cat 1 minima (200 ft AGL), it provides a 300 ft buffer. In the event of a performance-limited go-around, this buffer can be used to descend and clean up whilst easily ensuring that speed will be well above VMCL-2 when the nose is raised to climb away.
The Commit Altitude should be inserted on the MCDU PERF APPR page as the MDA, but is not a “not below” altitude in the conventional sense.
Autothrust is disconnected once stabilised on final approach. At the Commit Altitude with the landing assured, speed may be reduced to normal VAPP. In the case of two engines inoperative on the same wing, VAPP will be below the VLS displayed on the PFD (VMCL-2), e.g based on the MCDU VLS in case of loss of two engines on the same wing. Speed reduction below VMCL-2 is acceptable at this stage, as VMCL-2 is based on the use of TOGA thrust on the remaining engines, and adequate margins remain at normal approach speeds and thrust settings.
Go-Around
If a landing is not assured by the Commit Altitude (or immediately prior to L/G extension with engines 1 and 4 inoperative), then a go-around should be initiated. If the approach has been flown accurately, the speed will be at VLS.
TOGA thrust should be selected. At certain weights and CG positions, it may not be possible to satisfy the a target demands at VLS. If two engines are inoperative on the same wing, this may require leading with the inboard thrust lever. TOGA should be achieved on the outboard engine as soon as directional control permits, but without undue delay. When obstacle clearance is assured, accelerate to a speed at which the a target.can.be.satisfied.
　
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