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CONFIGURATION
When performance is limiting the takeoff weight, the flight crew uses TOGA thrust and selects the configuration that provides the highest takeoff weight.
When the actual takeoff weight is lower than the permissible one, the flight crew uses FLEX TO thrust. For a given aircraft weight, a variety of flap configurations are possible. Usually, the flight crew selects the configuration that provides the maximum FLEX temperature. This is done to prolong engine life.
On A340-500/600:
For any runway length, CONF 3 usually provides the highest FLEX temperature, and the tail clearance at lift off does not depends on the configuration. So, the flight crew should select CONF 3.
On A330 and A340-300:
The configuration that provides the maximum FLEX temperature varies with the runway length. On short runways, CONF 3 usually provides the highest FLEX temperature, and the tail clearance at lift off does not depends on the configuration. So, the flight crew should select CONF 3.
On medium or long runways, the second segment limitation becomes the limiting factor, and CONF 2 or CONF 1+F becomes the optimum configuration, in term of FLEX temperature.
NORMAL OPERATIONS
TAKEOFF
In these cases, the tail clearance at lift off depends on the configuration. The highest flap configuration gives the highest tailstrike margin.
There is a difference between twin and quadri, regarding this concern: The A330 has more tail clearance than the A340, that has quite often, takeoff speeds closer to VMU limitation. This is true with one engine inoperative. Since twin aircraft have more thrust margin for takeoff, this is even more the case with all engines operative.
On A340-300, selecting CONF 3 instead of 1+F increases the tail clearance by 1.5 to 2 ft, at the expense of a loss in FLEX temperature generally less than 3 °C.
Note: detailed effect:
? From CONF 1+F to CONF 2: Tail clearance increased by 0.5 to 1 ft, loss in FLEX temperature generally less than 1 °C.
? From CONF 2 to CONF 3: Tail clearance increased by 1 ft, loss in FLEX
temperature generally less than 2 °C.
The first degrees of flexible thrust have an impact on maintenance costs about 5 times higher than the last one.
Summary:
On A340-200/300, taking the above into consideration, the crew may decide to select CONF 2 or CONF 3:
? When the FLEX temperature is close to TREF, it is advisable to select one more step of flaps (compared to the optimum one).
? When the FLEX temperature is more than 15 °C above TREF, it is advisable to select CONF 3.
TAKEOFF TRIM SETTING
The main purpose of the pitch trim setting for takeoff is to provide consistent rotation characteristics. Takeoff pitch trim setting is automatic on ground on the A340-500/600, A330/ A340 Enhanced (with specific aircraft definition) and aircraft equipped with automatic trim setting function . It is set manually via the pitch trim wheel on other A330/340 models.
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A330/A340 机组训练手册 FCTM Flight Crew Training Manual 1(46)
