Landing Gear Flashcards
Under normal conditions, which system powers the landing gear?
Hydraulic system A
-extension and retraction
-nose wheel steering (normally)
Hydraulic system B
-normal brake system (and auto brake)
Describe how tires are protected from explosion during thermal expansion caused by hot brakes?
4 thermal fuse plugs in each inner wheel
Melt to release pressure at approx 177C or 352F
*not the answer but also have over pressure relief valve. Releases all pressure in tire if exceeds 375-450 psi
When is the landing gear lever locked? Can it be overridden?
Locked on the ground. Air/ground system energize lever lock solenoid.
Yes, with the Lever Lock Override Trigger
What do the red and green position lights on the forward landing gear panel indicate?
Red:
-landing gear is not down and locked (with with either or both thrust levers idle below 800 ft AGL)
-Related landing gear disagree with lever position (in transit or unsafe)
-pulling the gear lever out to select up will cause red lights to illuminate
-failure to slide gear lever IN when selecting down.
Green:
-related gear down and locked
-when extinguished not down and locked
What is the purpose of the aft overhead panel supplemental landing gear indicator lights?
Supplemental. Backup
Uses a dedicated proximity switch on each gear and associated wiring.
Gear is down and locked as long as one green indicator illuminated. Center or overhead panel
What protects the aircraft from loose tread or foreign object debris in the main wheel well during landing gear retraction?
Frangible fitting
Loose tire impacts fitting. Opens and relieves hydraulic pressure to associate gear retraction line.
Gear free falls down. Cannot be retracted til fitting replaced.
If the No. 1 engine fails, how is the hydraulic capability of system A affected? How is the gear raised at a normal rate?
System A engine driven hydraulic pump volume is lost. Engine pump 6x output of electric pump
Landing Gear Transfer Valve
-supplies normal volume of fluid to raise gear normal rate due to No. 1 N2 <50%
-automatic
-improves second segment climb
-valve auto repositions to allow Sys B engine pump to supply Hyd volume of fluid needed when:
—airborne
—No. 1 engine N2 below 50%
—gear lever positioned up
—either main gear not up and locked
When is the nose wheel steering active?
Is powered when nose gear is down and compressed by aircraft weight.
*powered by Sys A if NOSE WHEEL STEERING switch in normal guarded position. Powered by B with switch in ALT when on ground and B Sys quantity >21%. If B <21%, transfer valve return to normal position.
If normal and alternate brake pressure lost, how is braking accomplished? Are there any limitations?
Brake accumulator.
-pre charge of nitrogen
-pressurized by system B
-relief valve at 3500 psi
Trapped pressure. Only several (6) brake (or park brake) applications for eight hours.
Which hydraulic systems can pressurize the parking brake?
A
B
Brake Accumulator
Which brake systems have anti skid?
Normal
Alternate
Accumulator
Is the alternate brake system capable of supplying auto brakes?
No
Only with normal brake system and anti skid systems functional
When can RTO braking be armed? When is RTO braking available?
Armed:
-on ground
-anti skid and auto brake systems working
-AUTO BRAKE select switch to RTO
-wheel spin <60 kts
-forward thrust levers idle
Available:
-after reaching 90 kts or more
*once airborne automatically disarmed. AUTO BRAKE DISARM light not illuminated
*selecting RTO in flight does nothing. Illuminates disarm light
What does the Parking Brake Warning (red) light indicate?
The parking brake is set
Or, the parking brake shut off valve internal switch detects that the shutoff valve position is not full open.
Operates using battery power
