14. Landing Gear and Brakes

Question 1

Where is the 28V DC landing gear motor powered from?

Answer 1

Right generator bus

Question 2

What causes the warning horn to sound intermittently and landing gear switch handle lights to illuminate if gear isn’t down? (Both)

Answer 2

When flaps are in UP or APPROACH, and both power levers are retarded below a certain power level (hyd 85% N1, elec unspecificied), and,

When the flaps are beyond APPROACH both are activated and can’t be cancelled

Question 3

What does the WARN HORN SILENCE button do?

Answer 3

Silences the warning horn. Switch handle lights remain on. Warning system is rearmed if power levers are advanced sufficiently

Question 4

What holds gear in the retracted position? (Electric)

Answer 4

Friction in the jackscrew assembly in each actuator

Question 5

How is the nose gear held in the locked down position? (Elec and hydraulic)

Answer 5

By an over-centre condition of the drag brace (both).

Hydraulic also by an internal lock mechanism in the hydraulic actuator

Question 6

How are the main gear held in the locked down position?

Answer 6

By a notched hook and plate attachment on the drag braces

Question 7

List the steps for an emergency gear extension? (Electric)

Answer 7

• Reduce speed to 130kts
• landing gear handle in DN position
• pull LANDING GEAR RELAY cb
• pull up on emergency engage handle and turn it clockwise to the stop (disconnects electrical power from the motor and engages emergency drive system)
• pump emergency handle until 3 greens

Question 8

In an emergency extension what should be done if not 3 greens? (Both)

Answer 8

Continue pumping until resistance is felt (both)

On hydraulic leave handle at top of the stroke

Question 9

What prevents the landing gear being inadvertently retracted on the ground? (Electric and hydraulic)

Answer 9

J hook around handle. Safety switch on right gear completes circuitry to disengage the hook. Can be overridden by DN LOCK REL button (both)

On hydraulic also control circuitry is complete only when main gear safety switches sense an airborne condition

Question 10

What holds gear in retracted position? (Hydraulic)

Answer 10

When retraction is complete (approx 6 seconds), the gear actuators bottom out, and pressure increases rapidly. At 2,775 psi, the uplock pressure switch opens, and the pump motor deenergizes.
Since there are no gear uplock mechanisms, pressure in the retract side holds the gear retracted. When system leakage drops the pressure to 2,475 psi, the uplock pressure switch closes power pump.

Question 11

List the steps for an emergency extension? (Hydraulic)

Answer 11

• landing gear handle in DN position
• pull LANDING GEAR RELAY cb
• actuate hand pump emergency handle until 3 greens
• place pump handle in down position, and secure in retaining clip

Question 12

What is the nose wheel steering range?

Answer 12

14deg left to 12deg right, but can be considerably increased by differential braking/thrust

Question 13

What are landing gear speed limitations?

Answer 13

V LO
Extension- 181 kias
Retraction- 163 kias

V LE- do not exceed with gear extended
181 kias

Question 14

What functions are controlled by the left gear safety switch? (8)

Answer 14

• safety valve
• preset solenoid
• dump solenoid
• door seal solenoid
• ambient air modulating valves
• stall warning
• stall warning heat control
• landing gear solenoid (hydraulic gear)

Question 15

What functions are controlled by the right gear safety switch? (4)

Answer 15

• landing gear handle lock solenoid
• landing gear motor
• landing gear emergency control
• flight hourmeter

Question 16

How is gear travel up or down limited? (electric)

Answer 16

Limit switches control a dynamic brake relay which simultaneously brakes the motor circuit and completes a circuit through the armature and unused field winding to stop motor

Question 17

What are the hydraulic gear cycle limits?

Answer 17

1 cycle (up and down) every 5 minutes for a total of 6 cycles. Then a 15 minute cool down period