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frankice
15th Nov 2019, 05:01
Good morning Chaps

I was reviewing the L/G System, the FCOM states that the LGCIUs process the signal from four disconnect proximity switches, than send them to the SFCCs.

Does anyone know why this signal is sent to LGCIU and not directly to the SFCC? (Why does it have to pass through the LGCIU)

Regards

Francesco

MD80rookie
15th Nov 2019, 08:57
Perhaps one reason is to determine wether to select Config 1 or config 1+F via the ground/air logic.

LEVEL600
15th Nov 2019, 13:40
Because LGCIU is responsible for all proximity switches signal processing for other system.

B737NG_Pilot
15th Oct 2020, 02:43
Because LGCIU is responsible for all proximity switches signal processing for other system.

Why are these called "flap disconnect proximity switches"

tubby linton
15th Oct 2020, 09:38
A flap connection strut connects the adjacent inboard and outboard flap ends. Attached to the flap connection strut are flap disconnect sensors. The sensors send signals to stop the flap movement, if the strut movement is more than the specified limits
The proximity switches of the FLAP disconnect detection system send signals to the Landing Gear Control Interface Units ( LGCIU ). The LGCIU send this signals to SFCC1 and SFCC2. If too much flap movement is found, then the conditions listed below occur: - the flap PCU is switched off - a warning is sent to the flight crew.
Flap Attachment Failure Detection Sensors The SFCCs monitor the flap-attachment failure detection sensors to find connection failure. If the SFCCs receive a flap disconnect signal: - the valve block solenoids on the PCU are de-energized - the POBs lock the two hydraulic motors - the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message. System reset is only possible on the ground. The ECAM display unit shows a failure message if: - the SFCC gets different data from the two sensors on the same wing or - one sensor gives incorrect data.

Flap Interconnecting Strut The flap interconnecting strut has these functions: - it lets the inner and the outer flaps move independently by a specified limit - it gives a different load path for the flap drive system if there is an attachment failure - it sends data to the SFCC when the independent movement of the inner and outer flaps is more than the specified limit - it absorbs energy if a flap drive disconnect occurs. The flap interconnecting strut has: - a housing - two flap-attachment failure detection sensors - an actuating rod - a target - a ball piece-a sleeve.

The housing contains the actuating rod, the sleeve and the ball piece. The target is at the end of the actuating rod. The two sensors on the housing align with the targets on the actuating rod, with the flaps in their normal postion. The actuating rod has a total travel of 18 mm (0.7086 in.) in each direction from the center position. The limit of independent movement between the flaps is 14.5 mm (0.5708 in.). The sensors send a target-far signal to the LGCIU if the target moves more than 15 mm (0.5905 in.) from the center position.

System Jam Detection The SFCC will find a system jam if the system speed is below 2% nominal for more than 4 seconds. When the SFCC's find a system jam: - the valve block solenoids on the PCU are de-energized - the POBs are applied and stop their related hydraulic motors - the SFCCs give a class 1 level 2 caution and the ECAM display unit shows a failure message. If the SFCC's receive a new correct CSU signal, the SFCC's go back to their normal operation. If there is low hydraulic pressure, the SFCC's stop system jam monitoring.

B737NG_Pilot
15th Oct 2020, 14:05
Thanks Tubby... this is exactly what I was looking for. Very well explained. Any chance you would be having a schematic for the following. All related to Cargo Door. Manuel selector valves
Locking shaft
Locking handle
Safety shaft
Door sills