Landing gear and brakes
The landing gear on Cessna C525 Citation series is actuated by the landing gear lever to either the extend or retract position. During gear extension, hydraulic pressure retracts the uplocks and then extends the gear actuators. The actuators mechanically lock in the extend position. Upon retraction, hydraulic pressure unlocks the actuators and retracts the gear into the uplocks.
Hydraulic pressure automatically shuts off when the gears are down and locked on extension or up and locked on retraction.
Three green annunciators illuminate when the nose, left main, and right main gear are down and locked. These lights are not illuminated in the retracted position. A red GEAR UNLOCKED annunciator is illuminated anytime all landing gears are not locked in the position selected by the landing gear handle.
A “LANDING GEAR” or tone audio warning is provided by the warning/caution advisory system if either of the following conditions occur and the landing gear is not down.
1. Airspeed below 130 KIAS (copilot’s indicator), and either throttle is below approximately 85% N 2 . Warning can be silenced.
2. Flaps are extended beyond the TAKEOFF AND APPROACH setting. Warning cannot be silenced.
Emergency landing gear extension is provided by two emergency gear handles located below the landing gear handle. Pulling the Tee handle retracts the uplocks, allowing the landing gears to free fall to the extend position. Some yawing can be required to achieve green lights on all gear. Rotating the extended Tee handle 1/4 turn clockwise will lock the handle. After the Tee handle has been pulled, the round collar handle can be pulled to discharge the nitrogen blow down system. Nitrogen will retract the uplocks, in the event they did not release mechanically, and then extend the gear. After the gear is extended, the collar and Tee handle can be pushed in for knee clearance. If significant resistance is encountered, the handle should be left extended to prevent cable crimping.
- Prior to using the emergency extension, the landing gear handle must be down to prevent possible energizing of the gear hydraulic system to the retract position.
- Once the emergency gear extension system has been used, do not attempt to raise the gear.
The CJ4 has a fully retractable, hydraulically actuated tricycle landing gear with mechanical up-locks, pneumatic back-up deployment system and mechanical nose-wheel steering. Trailing-link main landing gear legs have an electronic, anti-skid wheel-braking system. Each leg has a single tyre, the nose-wheel is fitted with a chine each side to deflect surface contamination away from the engine intakes. The aircraft may only be operated from paved surfaces.
The hydraulic systems for undercarriage deployment and normal braking are independent (for undercarriage deployment hydraulic system, see Hydraulic System, below). Main brake pressure is provided through a dedicated DC electric hydraulic pump and accumulator. The pneumatic back-up system is shared by the two parent systems providing emergency undercarriage lowering and emergency wheel braking when required. The electronic braking and anti-skid systems both require DC power and are not connected to the Emergency Bus. The anti-skid system includes touch-down protection. With the anti-skid system inoperative the required scheduled landing distance is almost doubled.