737 Flight Controls Flashcards
In what phase of flight does the Speed Trim System (STS) operate most frequently?
during takeoff, climb and go-arounds
What will cause the SPEED BRAKES EXTENDED light to come on?
In flight:
If speed brake lever is beyond the armed position and
1. TE flaps are extended more than flaps 10
- OR -
2. Radio Altitude is less than 800 ft
On Ground:
* Speed brake lever is in the DOWN position but the spoilers are not stowed
What is the meaning of an amber LE FLAPS TRANSIT light?
- Any LE (leading edge) device in transit
- Any LE device not in programmed position with respect to TE flaps
- An LE uncommanded motion condition exists (two or more LE flaps or slats have moved away from their commanded position)
- During alternate flap extension, the LE FLAPS TRANSIT light illuminates until the LE devices are fully extended and TE flaps reach flaps 10.
What is meant by the Flight Control panel LOW PRESSURE light?
Indicates low hydraulic system pressure (A or B) to ailerons, elevator and rudder.
- deactivated when STBY RUD switch is activated and standby shutoff valve opens
What is the meaning of the amber FEEL DIFF PRESS light?
Indicates excessive differential pressure in the elevator feel computer. This can happen when either one of the hydraulic systems fails or one of the elevator feel systems fails.
What is the speed trim system?
What is the meaning of the amber SPEED TRIM FAIL light?
The speed trim system (STS) is a speed stability augmentation system designed to improve flight characteristics during:
* Low gross weight
* Aft center of gravity
* High thrust (Autopilot not engaged)
- Indicates failure of the speed trim system (STS)
- Indicates failure of a single FCC channel.
- when the MASTER CAUTION recall is pressed a FLT CONT will illuminate
What is the meaning of the amber MACH TRIM FAIL light?
- Indicates failure of the mach trim system.
- Indicates failure of a single FCC channel when the MASTER CAUTION recall is activated and light extinguishes when Master Caution System is reset
What is the meaning of the AUTO SLAT FAIL light?
- Indicates failure of the Auto slat system.
- Indicates failure of a single Stall Management/Yaw Damper (SMYD) computer when illuminated during MASTER CAUTION recall.
What is the meaning of the amber YAW DAMPER light?
Yaw damper not engaged
What is the meaning of the amber SPEED BRAKE DO NOT ARM
When speed brake lever is armed the light indicates abnormal condition or test input to the automatic speed brake system.
During landing, indicates wheel speed has dropped below 60 kts and the speed brake lever is not yet in the DOWN position. When speed brakes are down the light goes out.
Explain the function of the FLT CONTROL switches located on the Forward Overhead panel.
STBY RUD - activates standby hydraulic system pump and opens standby rudder shutoff valve to pressurize the standby rudder power control unit.
OFF - closes flight control shutoff valve which isolates the ailerons, elevators and rudder from the associated hydraulic system.
ON (guarded position) normal operating position
Explain the function of the Control Column Stabilizer cutout switches. (This seems to be the same as question FCTL 011)
They stop the operation of the main electric and autopilot trim when the control column movement opposes trim direction.
Note: This mechanism is inside the control column near the floor. It senses excessive pressure on the yoke that opposes trim direction.
What is the purpose of the STAB TRIM OVERIDE switch on the aft Electronic panel?
OVERIDE - Electric trim can be used regardless of control column position. It bypasses the control column actuated stabilizer cutout switches to restore power to the Stabilizer Trim switches on the Control Wheel.
NORM (guarded position) - normal operating position
Explain the function of the STAB TRIM Cutout switches on the Control Stand. (This seems to be the same question as FCTL 014)
MAIN ELECTRIC:
NORMAL - normal operating position
CUTOUT - deactivates control wheel trim with operation
AUTOPILOT:
NORMAL - normal operating position
CUTOUT - deactivates autopilot stabilizer trim operation. Autopilot disengages if engaged
How does the Flap Load Relief system operate?
When the flaps are set at 40, the TE flaps:
- retract to 30 if airspeed for flaps 40 is exceeded and then they will re extend when airspeed is reduced below flaps 30.
- The same thing happens with flaps 30 - they will retract to 25 and then go back again when speed is lessened
How are primary flight controls powered?
They are powered by redundant hydraulic sources - System A and B. Either source can power all flight controls.
The ailerons and rudder can be operated manually if required.
The rudder may be operated by the standby hydraulic system if systems A and B pressures are not available.
What does the ALTERNATE FLAPS master switch do?
OFF (guarded position) - normal operating position
ARM - closes TE flap bypass valve and activates standby pump and arms the ALTERNATE FLAPS Position Switch.
Explain positions of Speed Brake Lever
DOWN - faired position
ARMED - automatic speed brake system armed
50% - Under certain high gross weight/airspeed combinations if the speed brakes are deployed to the FLIGHT DETENT position they will automatically retract to the 50% of FLIGHT DETENT position.
FLIGHT DETENT - all spoilers move to their maximum position of - inflight use only
UP - all flight and ground spoilers are extended to maximum position - ground use only
Explain function of the Speedbrake Load Alleviation Feature.
It limits the deployment of speed brakes under certain high gross weight/airspeed combinations. If the crew wants to increase speed brake deflection beyond 50% they must hold the speed brake lever to do so.
