Pitch Trim Setting [PDF]

Zitiervorschau

Operational Liaison Meeting FBW aircraft - Montreal

Pitch Trim Setting

4 Content z Pitch Trim : On ground z Pitch Trim : In flight z New PITCH TRIM/MCDU/CG DISAGREE caution z New automatic takeoff pitch trim setting z Conclusion

Pitch Trim Setting

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4 Content z Pitch Trim : On ground z Pitch Trim : In flight z New PITCH TRIM/MCDU/CG DISAGREE caution z New automatic takeoff pitch trim setting z Conclusion

Pitch Trim Setting

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4 Pitch Trim : On ground z The crew has to manually select the takeoff pitch trim. z Airbus takeoff trim setting definition is a compromise

between: „

Providing consistent rotation characteristics, whatever the aircraft CG may be, „ Being close to the ideal trimmed position at V2+10 with all engines running, AND „ Keeping it simple. z Trim setting for takeoff only depends on the aircraft CG: Ö Relationship TRIM/CG indicated on the pitch trim wheel. Pitch Trim Setting

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4 Pitch Trim : On ground z However, takeoff trim setting also has to be limited

Î Definition of the GREEN BAND z To define the green band, out-of-trim takeoffs have

been demonstrated : „

At FWD CG with trim set in the nose-down limit of the green band „ At AFT CG with trim set in the nose-up limit of the green band

Î The takeoff green band is defined to satisfy these “abuse cases”

Pitch Trim Setting

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4 Pitch Trim : On ground z Takeoff green band definition

Takeoff green band

Out of Trim At FWD CG

Aircraft Aircraft heavy heavy to to rotate rotate Aircraft Aircraft light light to to rotate rotate Out of Trim At AFT CG

FWD CG limit for T/O Pitch Trim Setting

AFT CG limit for T/O 6

4 Pitch Trim : On ground z Takeoff pitch trim setting : „

Relationship between takeoff CG and “nose up/down” THS value is given in the QRH

„

Set the takeoff CG on pitch trim wheel

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Pitch Trim Setting

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4 Content z Pitch Trim : On ground z Pitch Trim : In flight z New PITCH TRIM/MCDU/CG DISAGREE caution z New automatic takeoff pitch trim setting z Conclusion

Pitch Trim Setting

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4 Pitch Trim : In flight z Automatic pitch trim in normal or alternate law with

protection calculated by the ELAC/FCPC z The pitch trim depends on : – The aircraft CG, weight, configuration – The altitude and speed

Example for the A330-300 TRIM SETTING

Altitude or weight variation

-3000ft or 30 T

-2

-3

Mach variation M : -.03

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220 T 37000ft M.81

Reference curve -5

Pitch Trim Setting

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30

CG (%) 34

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4 Pitch Trim : In flight z Consequently :

There is no unique relationship between CG and trim position in flight : Trim may be out of the green band z Any pilot action on the trim wheel : „ Disarms the autopilot, if armed. „ Adds trim order, if in manual flight. z In case of unavailability of the automatic trim: Autotrim unavailable : The crew has to manually trim the aircraft

Pitch Trim Setting

Autotrim and elevators unavailable : The crew only has the pitch trim wheel to adjust aircraft pitch

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4 Content z Pitch Trim : On ground z Pitch Trim : In flight z New PITCH TRIM/MCDU/CG DISAGREE caution z New automatic takeoff pitch trim setting z Conclusion

Pitch Trim Setting

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4 New PITCH TRIM/MCDU/CG DISAGREE caution z New alert developed on the A340-500/600 to avoid an

erroneous trim setting before takeoff z This caution will be activated when : „

The T/O CONF test P/B is pressed or takeoff thrust is set, and, „ A discrepancy is detected between :

FWC

The trim setting, entered on the MCDU, by the pilot Pitch Trim Setting

The theoretical trim setting The actual trim deflection (green band), computed used by F/CTL computers by the FWC 12

4 New PITCH TRIM/MCDU/CG DISAGREE caution z Computations „ TRIM_MCDU

FMS

FWC

Theoretical THS setting : TRIM_MCDU THS from Load & Trim Sheet entered by the crew Pitch Trim Setting

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4 New PITCH TRIM/MCDU/CG DISAGREE caution z Computations „ TRIM_CG

FWC Aircraft FCMC CG THS = f(CG)

Computed THS setting : TRIM_CG Pitch Trim Setting

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4 New PITCH TRIM/MCDU/CG DISAGREE caution z Computations „ ACTUAL_TRIM

Actual Pitch Trim FCDC

FWC

Actual Trim setting : ACTUAL_TRIM Pitch Trim Setting

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4 New PITCH TRIM/MCDU/CG DISAGREE caution z Logic description T/O CONF test P/B pressed:

TRIM_MCDU

TRIM_CG

ACTUAL_TRIM

Comparison : TRIM_MCDU - TRIM_CG TRIM_MCDU - ACTUAL_TRIM TRIM_CG - ACTUAL_TRIM

One value differs from the other two by < +/-1.5°

NO CAUTION Pitch Trim Setting

One value differs from the other two by > +/-1.5°

CAUTION : PITCH TRIM/MCDU/CG DISAGREE 16

4 New PITCH TRIM/MCDU/CG DISAGREE caution z This new logic covers the following type of errors: „

Comparison TRIM_MCDU - TRIM_CG – MCDU trim setting typo – Fuel distribution different from the load & trim sheet

„

Comparison TRIM_MCDU - ACTUAL_TRIM – Trim setting omission

„

Comparison TRIM_CG - ACTUAL_TRIM – Same as above – Consolidate the caution if one information is missing

z This logic assumes that the ZFCG entered in the MCDU

is correct Pitch Trim Setting

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4 New PITCH TRIM/MCDU/CG DISAGREE caution z Degraded case : „ One value is unavailable:

Example TRIM_MCDU

T/O CONF test P/B pressed :

TRIM_CG

ACTUAL_TRIM

Comparison : TRIM_CG - ACTUAL_TRIM One value differs from the other by < +/-1.5°

NO CAUTION

„

One value differs from the other by > +/-1.5°

CAUTION : PITCH TRIM/MCDU/CG DISAGREE

Two or three values are unavailable: Î PITCH TRIM/MCDU/CG DISAGREE alert is inhibited

Pitch Trim Setting

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4 New PITCH TRIM/MCDU/CG DISAGREE caution z Remark: PITCH TRIM/MCDU/CG DISAGREE alert is

inhibited when ACTUAL_TRIM is outside the authorized limits, i.e. not in the green band. ÎPITCH TRIM NOT IN TO RANGE warning is then activated z New computers needed: „ New FWC - to be able to perform the comparison and activate this new caution „ New FMS - to send the MCDU THS setting entry to the FWC

Pitch Trim Setting

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4 Content z Pitch Trim : On ground z Pitch Trim : In flight z New PITCH TRIM/MCDU/CG DISAGREE caution z New automatic takeoff pitch trim setting z Conclusion

Pitch Trim Setting

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4 New automatic takeoff pitch trim setting z New logic developed on the A340-500/600 to activate

an automatic pitch trim setting before takeoff Ö Based on FCMC CG computation Ö Could be overridden by pilot input z Logic description

When the three hydraulic systems are available:

Aircraft FCMC FCPC CG

Pitch Trim Setting

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4 New automatic takeoff pitch trim setting z Logic description (Cont’d) „

If the pilot has not entered the ZFCG when hydraulic systems are available : Î No automatic pitch trim activation

„

If the pilot changes the CG after the automatic pitch trim setting : Î No automatic pitch trim reactivation. New pitch trim has to be set manually

„

Monitoring via the PITCH TRIM/MCDU/CG DISAGREE ECAM caution remains available

Pitch Trim Setting

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4 New automatic takeoff pitch trim setting z Automatic pitch trim setting also developed for

touch-and-go „

Provide an automatic takeoff trim setting in case of a touchand-go

„

As on other fly-by-wire aircraft, automatic trim setting reset is activated at landing, when : • Both MLGs are compressed + 1 second, and • The ground spoilers are not extended

„

If a touch-and-go is initiated (Vc > 80 knots and ground spoilers not extended) ÎPitch trim is automatically set to the takeoff position according to the green band law ( from Cg recorded at 100 ft, before the flare)

Pitch Trim Setting

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4 Content z Pitch Trim : On ground z Pitch Trim : In flight z New PITCH TRIM/MCDU/CG DISAGREE caution z New automatic takeoff pitch trim setting z Conclusion

Pitch Trim Setting

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4 Conclusion z On ground : „ Takeoff pitch trim only depends on aircraft CG „ Pilot pitch trim setting must be in the green band Î Pilot action is required z In flight : „ Pitch trim depends on several parameters „ May be out of the green band Î No pilot action is required z For the A340-600/500, improvements to : „ Avoid erroneous takeoff pitch trim setting, with the PITCH TRIM/MCDU/CG DISAGREE ECAM caution „ Decrease pilot workload with the automatic takeoff / touch-and-go pitch trim setting Pitch Trim Setting

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