Landing Gear Flashcards by Richard hunt

What is the landing gear retraction/extension time?

25 seconds

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What type of motors are used for normal and emergency extension?

 Normal = 2 hydraulic motors (extension and retraction)

 Emergency = 2 Electric motors (extension)

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What are the normal hydraulic systems for each of the gear?

NLG - #1 FWD MLG - #4 AFT MLG - #1

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The landing gear can be extended without normal electrics AND without normal hydraulics?

FALSE - Need normal hydraulics OR normal electrics to get gear down

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How many gear doors does each main gear pod have?

2 (inboard & outboard)

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Describe MLG retraction:

 GREEN WHEELS - MLG is down and locked, positioning collar is locked
 RED WHEELS – Caster powerback positioning collar unlocks, bogie rotates 90 inboard
 INTRANSIT – Downlock unlocks the sidebrace
 UP - All MLG doors close and lock (MLG doors don’t have uplocks – have only 4 door locks on outboard doors)

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Approximately how long does it take for normal MLG wheel spin down after takeoff (uses 7-port valve)?

5 Seconds

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Describe MLG extension:

 UP - Gear is up and locked
 INTRANSIT – when first MLG door lock unlocks
 RED WHEELS – MLG downlock locks sidebrace; bogie rotates 90 outboard
 GREEN WHEELS - Caster powerback positioning collar is locked, forward rolling gear

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How many gear doors are part of the NLG system?

5 (two inboard, two outboard, kneeling door on aft part of fairing)

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DISCUSSION: MLG EMERGENCY EXTENSION (takes about 3 minutes)

a) Place EMERG EXT switch to EXTEND
b) Return switch to NORMAL if INTRANSIT indication is not obtained within 5 seconds
c) Simultaneously, the emergency extension electric motors are electrically energized and the emergency isolation valve isolates the normal hydraulic system from the normal extension/retraction manifold and pressurizes the emergency gear extension manifold with alternate hydraulic system pressure (electrically controlled)
d) MLG door locks unlock (alternate hydraulics) and clutches disengage the normal extension hydraulic motors and engage the electric motors to the extension/retraction gearboxes using the alternate hydraulic system
 Get INTRANSIT indication when door lock unlocks
e) Electric motors (Main AC) extend the MLG
f) Alternate hydraulic pressure locks the MLG sidebrace lock
 Get a RED WHEELS indication when the sidebrace locks
g) Using alternate hydraulic pressure, the emergency bogie rotation cylinder rotates the bogies to the zero-degree position
h) Alternate hydraulic pressure locks the positioning collar lock
 Get GREEN WHEELS when the positioning collar locks
 Also get EMERG SW ON light on (indicates forward rolling green wheels)

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Anytime you use the emergency extend switches, which hydraulic systems are you using for each respective set of gear?

 NLG - #4
 FWD MLG - #1
 AFT MLG - #4
If Emergency hyd press from alternate (emergency) source is also not available (both systems #1 and #4 are lost):
 CED Accum
 L MLG Emergency Accum
 R MLG Emergency Accum

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How many gear door locks are on the MLG?

 MLG = 4 locks each

 NLG = 8 locks

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NLG has a two-speed gearbox, describe its operation:

It has a high speed/low torque mode for extension and retraction; a low speed/high torque mode for kneeling

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How are the NLG doors powered during normal and emergency operations?

 Normal: powered by #1 hydraulics (hydraulic motor)

 Emergency: powered by electric motor

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How many degrees from center must the NLG be in order to retract?

5°

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Describe NLG retraction:

 GREEN WHEELS - NLG drag brace (downlock) is locked, NLG down
 RED WHEELS – Drag brace unlocks (NLG retracts, uplocks lock)
 INTRANSIT - Doors intransit – start to close
 UP - All “8” gear door locks are closed; locks and door closed targets met

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Describe NLG extension:

 UP - Gear is up and locked (locks locked & door closed, targets met)
 INTRANSIT – When first NLG door unlocks
 RED WHEELS – Both NLG doors are fully open (strut begins to extend)
 GREEN WHEELS – NLG drag brace (downlock) is locked, NLG down

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The gear handle is locked down until:

MLG struts are fully extended after takeoff

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What electrical power sources are used for Emergency Extension of the gear?

 Emergency Extend Switches – Main DC #2
 NLG Emergency Extension Motor & Door Motor – Fwd Main AC #2
 MLG Emergency Extension Motors – Aft Main AC #1, 2, 3, 4

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When the gear are DOWN, what does the BOGIE PITCH CWA mean?

On when bogie is greater than 15 nose down or greater than 11 nose up and side braces are locked

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When the gear are UP, what does the BOGIE PITCH CWA mean?

Shows erroneous side brace signal and could cause damage if gear handle is placed to down position

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During NLG emergency extension, the EMERG SW ON light comes on when the switch is placed to extend and:

The first NLG door reaches the fully open position.
(NOTE: If the Fwd RH Lock is unlocked when the EMER EXT switch is placed to Extend, the EMERG SW ON light comes on when the NLG is down and locked)

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During MLG emergency extension, the EMERG SW ON light comes on when the switch is placed to extend and:

The affected MLG is down and locked and the positioning collar is engaged

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What if the EMERG SW ON light comes on when the NLG is up and locked?

Warns of an erroneous NLG door open signal & structural damage could occur if NLG is extended

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What does the red light in the gear handle indicate?

 Gear lever UP: any NLG or MLG gear door locks are not in locked position  Gear lever DOWN: NLG is not down & locked or any MLG caster powerback positioning collars are not engaged

What is indicated when the landing gear warning horn sounds?

 Airspeed < 200 KCAS for 5 seconds  Radar altimeter below 1000 feet  Any throttle is below 14 degrees lever angle (approx.. 60% N1 at pattern altitudes) for 5 seconds  ADS switch in safe  NLG not down and locked or any MLG positioning collar not locked  Flaps extended beyond 80% and NLG not locked or any MLG positioning collar not locked

The gear warning horn will sound if: (can NOT be silenced)

Flaps greater than 80% and NLG not down/locked or any MLG positioning collar locks are not engaged

To silence the landing gear warning horn with the throttle, the triggering throttle(s) must be increased above ____ degrees lever angle (approximately 70% N1 at pattern altitude).

If both CARAs are failed/off, the landing gear warning horn will sound when the airspeed is below ____ KCAS for 5 seconds, regardless of the altitude, if all other conditions when horn can be silenced are met.

180

When the radar altitude is less than 1,000 feet and airspeed is less than 200 KCAS for 5 seconds, the airspeed must be increased to greater than ____ KCAS or radar altitude increased to greater than or equal to _____ feet to reset the landing gear warning horn.

210; 1000

The landing gear warning horn will not sound when the Cargo Doors Aft Arming switch is in the __________ position unless the flaps are greater than or equal to ____ % and any of the landing gear are not down and locked.

ADS READY; 80

What is the range of nosewheel steering with the wheel (tiller)? The rudders?

+/-60, 5°, (+2, -1)

What hydraulic systems power the NLG steering, normal and emergency?

Normal - #1 | Emergency - #4

What is the transition time between wheel and rudder steering?

3 seconds

What hydraulic systems power rudder pedal steering?

#1 hydraulics only

How do you steer if #1 and #4 hydraulic systems are gone?

NLG will caster (be cautious), use differential braking and asymmetric thrust (aka…good luck)

Both aft MLG caster up to ___ degrees of center.

When castering the aft MLG, what asymmetry protection is built into the system?

None, no asymmetrical restraints (split bogie is possible)

When centering the aft MLG, what asymmetry protection is built into the system?

If asymmetry reaches 8, the gear nearest to center stops until the other gear gets within 5 of the other, then both continue

Which hydraulic system supplies pressure for the aft main gear bogie emergency positioning switches?

What hydraulic system powers the brakes: normal, alternate & emergency?

 Normal - #4 Normal brake pressure is supplied from the fwd gear hydraulic manifold (Hyd sys 4 thru fwd gear down rotate line for each side)  Alternate - #1 Alternate brake pressure is supplied from the aft gear hydraulic manifold (Hyd sys 1 thru aft gear down rotate line for each side)  Emergency - Emergency brake accumulator (system 4)

How many brakes per bogie?

In EMERGENCY, a fully charged brake accumulator may provide up to ______ full brake applications.

The EMER HYD light will come on if:

The accumulator has a min pressure of 1300 psi & brake switch is in EMER

Anti-skid will prevent locked wheel above ________ kts.

Why would you not want to takeoff with anti-skid switch in TEST ARM?

Only partial anti-skid modulation; may suddenly release then reapply brake pressure and damage the gear

What do the BRAKES and NO BRAKES light mean?

Brakes: All brakes receiving pressure (12 pressure lines) | No Brakes: No brakes are receiving pressure (12 pressure lines)

How does anti-skid work in EMER BRAKES?

It doesn’t

What reasons the ANTI-SKID OFF LIGHT would illuminate?

 Anti-skid switch OFF  Brake switch in EMER  Anti-skid in TEST ARM, TEST 1 is depressed & alt power supply is inop  Anti-skid in TEST ARM TEST 2 is depressed & normal power supply is inop  Anti-skid switch in TEST ARM & Test 3 depressed  Anti-skid switch ON and overvoltage occurs  Loss of two electrical power sources to the anti-skid control box

What does the DET FAIL light indicate? Ground or in-flight?

 With anti-skid ON, a skid control malfunction on one or more pairs of brakes which causes one or more pairs of wheels to free wheel for more than 3 seconds;  DET FAIL will NOT come on inflight.

Can EDS provide information about which pair of brakes is freewheeling after receiving a DET FAIL indication?

 Yes, The output current for each detector pair can be determined by checking the appropriate anti-skid test points in EDS. This allows the crew chief to check hub sensors for free-wheeling on that particular pair of brakes.

What is the Seven-Port Valve?

 A mechanically driven scissor valve located on the aft portion of each MLG bogie. The Seven-Port Valve is a mechanical valve that’s position changes with the compression and extension of the MLG strut. When the strut is compressed (i.e. weight on wheels) down rotate pressure is able to provide pressure to the individual brake pad actuators for braking. When the strut is extended (i.e. weight is off wheels) the Seven-Port Valve mechanically shifts allowing reduced in-flight brake line pressure to port to the brakes for MLG wheel spin-down.

Where are the MLG spin-up detectors located?

``` X X XXXX XXXX (FWD) (1A2 & 2A1) ``` ``` X X XXX XXXX (AFT) (3A1 & 4A2) ```

What are you testing during the in-flight brake check?

Testing brake pressure switches only; 12 total, 3 per bogie, 1 for each pair of brakes

How do the MLG spin down after takeoff?

Once airborne, the anti-rotation valve opens and supplies approximately 100 - 110 psi hydraulic pressure to the brakes (takes 5 seconds to spin down); the 7 port valve prevents full hyd pressure to the brakes after weight is off the wheels

The landing gear lever is electrically powered by:

Main DC #1

If any MLG is more than _____ degrees from another, do not taxi the airplane

When taxiing above ____ knots, the anti-skid should be turned on to prevent locking of the braked wheels in the event excessive brake pressure is applied.

Thrust reverser operation during taxi will require _________ of the engine and thrust reverser system for structural integrity, FOD, and lubrication requirements, prior to the next flight.

An inspection

Limit taxi speed in congested areas to ____ knots or less.

For a min-radius 180-degree turn, taxi the airplane until ____ feet from the edge of the runway.

On a wet runway, the turn radius for a 180-dergee turn may increase by ____ feet.

Normal taxi speeds should be limited to ___ knots or less.

What do pilots/copilots look for when castering/centering?

 Pilots: MLG free lights, NW steering angle |  Copilots: MLG free lights, aft main gear position indicators; advise if improper indications

In order to accomplish a 180-degree turn on a 150-foot wide surface, asymmetrical thrust and brakes must be applied IAW Section 5. Forward speed must be held to _____knots maximum.

What do you do if MLG free lights fail to come on when the Caster switch is placed to CASTER or if they remain on after the switch is placed to CENTER and the gear are centered?

Comply with the CASTER/POWERBACK BITE Procedures in Section 2 (2.54). The Caster/Pwr Back Shutoff Valve Control CB (FE #5 panel) must be pulled and gear centered prior to flight.

During alternate caster procedure taxi turns, the aft MLG Bogie emergency Positioning switches can be used to position the aft gear in the opposite direction to the turn, not to exceed _____ degrees.

If hydraulic system ____ is lost, alternate caster procedures should be avoided or kept to a minimum. The MLG may not remain centered after releasing the MLG Bogie Emergency Positioning Switches.

On airplanes with inoperative rudder pedal steering, the pilot’s left hand will remain on the nose gear steering wheel until the rudder is effective for directional control (approximately _____KCAS).

Retraction malfunctions: What would you do if all 4 MLG gear remained GREEN WHEELS?

Anti-rotation failure; allow 2 minutes for spindown

Retraction malfunctions: What would you do if 1 AFT MLG gear remained GREEN WHEELS?

```  Check CBs  Landing gear lever – Down  Caster switch – Caster, Center  Landing Gear Lever – Up  If gear doesn’t retract, use MADAR prior to using Alt MLG Retraction Procedure (Standard Configuration in Section 2) ```

What alternate retraction procedures would you follow to retract only ONE MLG from a green wheels indication?

Alternate MLG Retraction Procedures – Standard Configuration

If one or more landing gear cannot be retracted and mission requirements dictate, continue flight. The remaining gear may be retracted using what procedures?

Alternate MLG Retraction Procedures – Non-Standard Configuration

Retraction malfunctions: What would you do if 1 MLG gear remained INTRANSIT?

(2.18, After Takeoff Climb Checklist – Engineer column) See Section 2 engineer procedure  mechanical vs no mechanical failures; specific detailed procedures must be followed. Section 2 (pg 2-142)

What happens if the Landing Gear Emergency Extend switches are left in “extend” for the MLG?

Normal and alternate brakes and caster may not be available if the Emergency Extend switches are left in the EXTEND position.

During Emergency MLG Extension (Normal Hydraulic Pressure Available), the MLG may not rotate above ____ KCAS.

185

After putting the gear down, if a gear position indicator is displaying RED WHEELS, proceed to the ______ Procedure.

Emergency Bogie Rotation

During Emergency MLG Extension, if the position indicator does not move to the intermediate position (INTRANSIT) within _____ seconds, immediately return the switch to the ______ position to prevent motor(s) burnout.

5; NORMAL

During Emergency MLG Extension, total extension time is _____.

3 minutes

When the flaps are at less than ___%, the landing gear warning horn protection associated with that flap setting will not be available.

If at any time, the MLG position indicator does not indicate down and locked (green wheels) and the MLG position indicator indicates zero degrees, check the _______ across the MLG rotation collar, locking collar and positioning collar are aligned vertically to form one line.

Black stripes

During Emergency MLG Extension (Normal Hydraulic Pressure NOT Available), using accumulator pressure only, the MLG MAY not rotate above ____ KCAS.

170

With loss of hyd systems 1 AND 4, ensure that the MLG Emergency accumulator is charged to _____ psi. Use the hand pump until the MLG indicates the zero-degree position.

3000

If hydraulic fluid in system #1 is lost, the NLG Steering shall be placed to ____.

EMER

With the loss of hydraulic systems 1 AND 4, emergency brakes shall be selected ______.

Just prior to landing

During Emergency NLG Extension, if the position indicator does not move to the intermediate position (INTRANSIT) within _____ seconds, immediately return the switch to the ______ position to prevent motor(s) burnout.

10; NORMAL

Illumination of the EMERG SW ON light while in flight with all of the Emergency Extend switches in the Normal position, indicates a failure of:

NLG door (open) switch card(s) or sensor circuitry.

Will NLG Steering be available if the NLG emergency Extend switch is left in the EXTEND Position?

If the NLG position indicator does not indicate down and locked (green wheels) and one down lock light is on, check the _____ for proper alignment.

Fiber optic scope target image

With loss of hyd systems 1 AND 4, the _____ is the only source of hydraulic pressure for initiating NLG extension.

CED accumulator

What is the minimum pressure for the CED accumulator to extend the NLG during Emergency NLG Extension?

2500 psi

The gear are currently UP, what would happen if you placed the gear handle down after observing a Bogie Pitch light on one of the MLG?

The affected MLG would immediately start to rotate as soon as the gear handle was placed down, resulting in structural damage

If the EMERG SW ON light is on (NLG up and Emergency Extend switches in normal) and the NLG sequence panel indicates only ONE door open light on, you should _____.

Extend the NLG by placing the gear handle down or using the NLG Emergency Extend switch

If the EMERG SW ON light is on (NLG up and Emergency Extend switches in normal) and the NLG sequence panel indicates BOTH door open lights on, you should _____.

Proceed with the Section 3 detailed procedures.

When placing the Emergency NLG or MLG extend switches to extend, how long do you have before you should observe an in transit?

5 Seconds for MLG and 10 Seconds for NLG

When do you do an inflight brake check?

 Emergency extension procedure  MLG CB pulled  Extension after Alternate MLG Retraction procedure

How do you do the Inflight Brake Check?

```  Antiskid – OFF  Press brake pedals – BRAKES light  Release brake pedals – NO BRAKES light  Select Alternate Brakes  Press brake pedals – BRAKES light  Release brake pedals – NO BRAKES light  Select Normal brakes  Anti-Skid – ON ```

How do you taxi with emergency brakes?

You don’t

How do apply Emergency Brakes?

Steady brake pedal pressure (do not pump brakes)

How many brake applications do you have with a fully charged accumulator?

Approximately 3

How many brake applications do you have with 1000 psi on the brake accumulator?

One

What if brake pressure is indicated on BOTH Normal and Alternate brake pressure gauge?

Antiskid Control CB is popped; brakes still work and will use system with highest pressure

What are the landing gear limiting airspeeds?

 MLG – 200 recommended  NLG & MLG – 250 Max  NLG may not retract above 225