ATA 32 cours finis LG 6q.odt

Main landing gear and door: each MLG is composed of a row of three leg which are **not structurally independent/interchangeable/ leg have diff geometry.** MLG is composed of a fixed cantilever structure attached to the fuselage at **11 points** along with **3 retractation actuator. Open doors with...

Main landing gear and door: each MLG is composed of a row of three leg which are **not structurally independent/interchangeable/ leg have diff geometry.** MLG is composed of a fixed cantilever structure attached to the fuselage at **11 points** along with **3 retractation actuator. Open doors with EBMA(hydro normal/elec back up)** The moving component are structurally independent Control and indications: L/G c.p (L/G lever red arrow when L/G **in not locked** down in approach configuration** (pedestal) 3 green arrows Location: main fitting = lower hinge pin and at the top to the cardan pin lateral link = lower hinge pin longitudinal = top main fitting the forward leg is also braced by 2 link = Upper and lower link Main Landing Gear Attachment points There are a total of 14 Main Landing Gear attachment points, including 3 Retraction Actuators attachment points. P33 ***moving parts :*** Shock absorber in two part pneumatic Nose landing gear and door: Fwd doors open mecha/ The gear automatically center upon full extension of the strut longitudinal folding dragstay consist of lower dragstay attached to main fitting and a panel type upper dragstay with removable pintle pin installed in bulkhead The folding dragstay is locked in the down position by lock link which are held over-center, on a integral stop by 2 tension spring SOSV allowing hydraulic pressure to the steering manifold when NLG is down position or to isolate the aircraft hydraulic pressure NLG up 2 forward doors hydraulically operated and closing when the gear is locked down 2 rear doors operate by 2 separate mechanical rods Location: ***Folding dragstay:*** - upper part connected to retractation actuator - lower to main fitting Extension and retraction: Emergency extension: - Close **cut off valves** = isolate the hydraulic supply pressure - open 3 vent valves = ensure all landing gear actuator are dumped in return-line for prevent inadvertent pressurization EMCU electrically operate EBMA Down lock MLG : one per leg, equipped with hook, a trigger and roller Spring assist to lock gear down in emergency mode ***MLG door up-lock:*** ***Nose door by-pass valve:*** can be operated on ground with a handle, allowing both front doors to be opened for maintenance purposes (mechanically release) NLG down lock spring = keep the overcenter in position locking the NLG in the down position ***Control and indications:*** ***Location:*** RDC = cargo bay 12s for sequence retraction 14s for extension in emergency 30s ***Wheel and brakes:*** Main wheel speed = tachometer BTMU: Temp sensors connected to btmu =\> IRDC (integrated remote data concentrato ***Anti skid:*** Compare wheel speed with aircraft speed (provided bu GADIRS) to release the brakes for that pair of wheel. - **touchdown protection** which inhibit braking before wheel spin up - prevent loss of braking efficiency (disable under 5m/s) Autobrake function: If use pedals, it overrides auto brk syst. for this further assistance to be available the ground spoiler p/b is not pressed for take off set on HI/RTO BCS: ** ***IRDC manages:*** - anti-skid - brake pressure control - data acquisition of pressure transducer switches and tachometer signal If both system are invalid EBCU take control Braking modes: Normal braking: ***Alternate braking:*** when normal is loss, supply by yellow and same normal function Park brake: ***Emergency brake operation:*** Pedals mechanically linked Ultimate braking: pedal braking unvailable ***Control and indications:*** ***U-turn:*** ** ***Location:*** Brake assemblie attached to axle on the trailing arm assemblies CPIOM-G = 1000VU IRDC = 1000VU EBCU = 1300VU avio bay RDC = cargo hold Shuttle valve = each leg Operation: Taxiing ground speed \< 90knots Brake pressure is not regulated and limited ***Steering:*** RVDT =... Transducers LVDT give a control spool feedback (degree active mode etec tableau !) ***Modes:*** ***Active mode:*** **less than 90 knots** on ground fully operative (pressure everywhere : sisv:swsv...) Semi-active mode: SAFETY VALVE CLOSED (wow, Gs \> 90knots) inhibited mode: ** Pre-land test: Internal test after the L/G lock down ***Control and indications:*** ***Parking brake light : lire 315*** ** ***Kneeling:*** Automatic reset function: only initiated **after the landing gear extended** 7,5s Manual reset function: and from LMWS when aircraft is stopped U-turn: **only available for military aircraft** Maintenance: lock valve is used for a wheel or brake replacement Location: kneeling actuator upper part of shock absorber