Cirrus SR20 Systems (Gen 3 Perspective) Flashcards
Engine
6 cylinder Teledyne Continental Electronic fuel injected IO-360 200 hp @ 2700 rpm Horizontally opposed, direct drive Air cooled
Airframe/control surfaces
Fuselage
Composite monocoque(orig. single-shell) (structural skin vs. Internal structural) two halves
4 seat roll cage
Access panels to firewall/avionics bulkheads
Wings
Single composite wing with conventional wing spar connects to fuselage at 4 locations ( under seats) contains fuel tanks and main landing gear attachment points
Ailerons are aluminum
Empennage
Horizontal stabilizer with 2 piece elevator
Vert stab is composite part of main structure
Rudder and elevator are aluminum
Control surfaces operate mechanically using torque tubes, cables and pulleys.
Trims operates on 28vdc and simply adjusts the neutral position on control yoke via electric motor
Flaps are electro mechanically activated (motor and torque tube) aluminum single slotted (28vdc, non essential bus)
50% 16 degrees
100% 32 degrees
Propeller system
Hartzell 3 blade constant speed prop
74”
Prop governed cable is connected to throttle control and has 3 settings: 2700 rpm takeoff and climb, 2500 cruise and normal ops, idle (less than 1000)
A prop governer uses a speeder spring (connected to cable on throttle control with a slotted guide for different flight areas listed above.
The prop governor reduces oil pressure during high power settings which allows the centrifugal force and spring to a high rpm setting (low pitch)
During throttle idle or low power positions, the governer via the flyweights open an oil duct that charges the hub (front of hub) which increases the pitch to a lower rpm
During engine failure, the prop is designed to fail at a high pitch giving you the least amount of drag. If it is windmilling however, moving the throttle to idle can force oil to the prop hum increasing pitch and decreasing drag.
Fuel system
100LL blue or 100 aviation grade (green)
58.5 gallons capacity
56 gallon usable (23 per side) tabs are at 13/ea side
Measured by electronic sensors or float probe(better) depending on year
Underwing fuel vents allow for positive pressure
Gravity fed to collector tanks/sump (better for maneuvering) where engine driven fuel pump draws fuel to the gasculator then metering system (determined by throttle position) to the flow divider and then to individual cylinders
A prime/boost electronic fuel pump uses prime for engine start momentarily then boost. This allows for proper pressure (4-5 psi). Boost also helps for fuel vapor suppression in hot fuel condition. Operates via 28vdc on main bus 2.
Oil system
8 qt (min 6) system used to lubricate/cool engine as well as prop pitch control
Cirrus Airplane Parachute System (CAPS)
Pulling the T ( 45 lbs of force) straight down (think pull up) handle will activate an extraction rocket rocket that employs a multi stage employment bag containing a parachute that is connected to a 3 point harness embedded in the plane structure.
Max demonstrated deployment speed 133 KIAS and requires about 400-500 ft to be effective
Electrical System
2 alternators
2 batteries
Batt 1 is 24 volt, 10 amp located front of firewall
Bat 2 is 2x12 volt, 7 amp connected in series to create 24 volts mounted behind aft bulkhead under CAPS. Batt 2 is charged via Ess bus 1
28 volt direct current (VDC) providing power to avionics, instruments, lights etc.
The brain is a Master Control Unit (MCU) located on the front left of the firewall. It controls all electronic operations and regulating/protection.
Alt 1 is a belt driven (mounted on front of engine and belt is around the prop flange) internally rectified (means uses AC to supply DC current) 75 amp, regulated to 28 volts.
Alt 2 is a gear-driven(back of engine on accessory case) internally rectified 40 amp regulated to 28.75 volts
Both alternators are self exciting which means they create their own electrical field/current even in a battery failure. They do need the battery initially to create the electrical field/current.
The MCU contains 3 power distribution busses: main bus 1, 2 and the Essential bus (Ess bus 1,2). The two mains are connected but has a diode(one way electrical valve) that prevents alt 2 from powering Main buss 1. It regulates alt 2 at 28.75 volts which is connected to Main bus 2.
Essential distribution buss is powered by both alternators and is controlled by the MCU. In the event of a Alt failure, the other alternator will provide power. In the event of double alternator failure, batt 2 will power.
Big picture:
If you loose alt 2, alt 1 will power whole system
If you lose alt 1, you have bat 1 power until it’s out.
Alt 1 is tied to main distribution bus which has very few unimportant components: cabin air control/fan, EVS (enhanced vision system), 12 volt recepticle, and MFD (but there is a backup MFD on main dist bus 2)
If you loose the essential distribution bus, think engine indicating, ADC, com 1, GPS Nav GIA 1, AHRS1, PFD, stall warning and trims.
