Landing Gear Flashcards
What is the landing gear retraction/extension time?
25 seconds
What type of motors are used for normal and emergency extension?
Normal = 2 hydraulic motors (extension and retraction)
Emergency = 2 Electric motors (extension)
What are the normal hydraulic systems for each of the gear?
NLG - #1 FWD MLG - #4 AFT MLG - #1
The landing gear can be extended without normal electrics AND without normal hydraulics?
FALSE - Need normal hydraulics OR normal electrics to get gear down
How many gear doors does each main gear pod have?
2 (inboard & outboard)
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)
Approximately how long does it take for normal MLG wheel spin down after takeoff (uses 7-port valve)?
5 Seconds
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
How many gear doors are part of the NLG system?
5 (two inboard, two outboard, kneeling door on aft part of fairing)
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)
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
How many gear door locks are on the MLG?
MLG = 4 locks each
NLG = 8 locks
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
How are the NLG doors powered during normal and emergency operations?
Normal: powered by #1 hydraulics (hydraulic motor)
Emergency: powered by electric motor
How many degrees from center must the NLG be in order to retract?
5°
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
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
The gear handle is locked down until:
MLG struts are fully extended after takeoff
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
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
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
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)
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
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
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).
20
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.
20
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?
4
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)