Turbocharged SR22 • System Description • Turbo Limitations • Normal Operating Procedures • Emergency Operating Procedures
Turbonormalize vs. Turbocharged A turbocharged engine has boosted manifold pressure above ambient sea level pressure, increasing the amount of power the engine is capable of producing. VS A turbonormalized engine compensates for the loss of ambient sea level pressure as the aircraft’s altitude increases. This allows the engine to maintain sea level rated horsepower up to very high altitudes. It does not increase the amount of horsepower the engine is capable of producing.
Keep in Mind • The engine always thinks it is at sea level • The turbo does NOT increase the rated horsepower of the engine
System Components
Upperdeck • The portion of the turbo system that starts after the turbo/compressor and ends at the throttle plate • The turbo will create and regulate 33 inches of pressure in the upperdeck before the intercoolers • Key Upperdeck components – Intercooler – Overboost control
Intercooler • The induction air from the turbo is warm and pressurized to approximately 33 inches of pressure • The intercooler cools the induction air for combustion and reduces pressure to 29.6 inches
Overboost protection • In the event of an overboost condition excess pressure will be relieved by the overboost poppet valve. • An overboost could be cause by: – Excessive oil pressure due to low oil temperature – Malfunction in the turbo system (absolute pressure control or wastegate)
Turbo • Turbo- uses accelerated exhaust gases to spin a compressor which increases the pressure in the upper deck. • Capable of +100,000 RPM • Maximum Turbo Inlet Temperature (TIT) is 1750 ° F, seen on MFD Engine page • Turbo is lubricated via the engine oil system. Turbo Compressor
Turbo… • A scavenger pump is added to pull oil through the turbo for cooling and lubrication.
Turbo… Twin Turbos supply pressure to the upperdeck
Turbo… • The turbo allows the engine to maintain 100% power up to 25,000’ MSL. • The maximum certification altitude of 25,000’ MSL is lower then the critical altitude. – Critical altitude is the altitude where the turbo can low longer maintain sea level pressure. Not a factor in the Cirrus • The amount of pressure produced by the turbo is a function of exhaust allowed to flow through the turbo.
Wastegate • The wastegate controls the amount exhaust that is allowed to flow through the turbo. • Air will take the path of least resistance. • A closed wastegate sends more exhaust through the turbo. • An opened wastegate allows Exhaust to bypass the turbo and be dumped overboard. • A spring holds the wastegate in the open position. Oil pressure closes the wastegate. • Each turbo has an interconnected wastegate.
Wastegate… True or False? An open wastegate sends more air through the turbo. FALSE Wastegate Actuator
Absolute Pressure Control • Moves the wastegate to manage the pressure created by the turbo. • Adjusts the wastegate to maintain approximately 33 inches of pressure in the upperdeck • Uses engine oil as hydraulic fluid to move wastegate.
Absolute Pressure Control… • Pressure from the upperdeck is plumbed into the absolute pressure control unit. • An aneroid inside the APC will expand and contract based on the pressure in the upperdeck. • Oil pressure to the wastegate controller is adjusted by the movement of the aneroid. • When the upper deck pressure drops the aneroid expands allowing oil pressure to close the wastegate sending more exhaust through the turbo.
Air Intake • Induction air passes through an air filter in the front right cowl. • The airflow splits after the air filter to the right and left compressor
Air Intake • An automatic alternate air source will open if the air filter becomes clogged (ice, dirt…) • Magnets hold alternate door closed. When the filter clogs the pressure drops in the intake forcing the door open. • The door will automatically close when the resistance is gone. • A message will appear on the MFD alerting the pilot when the alternate air door opens or closes.
Fuel Injectors • GAMI Injectors are included with the turbo kit. • Tuned injectors supply close fuel/air ratios to all cylinders, important for running lean of peak • Pressure from the Upperdeck is plumbed to each injector preventing the backflow of fuel through the injector at high altitude.
Engine Driven Fuel Pump • Upperdeck pressure is plumbed to an aneroid in the engine driven fuel pump controlling the amount of fuel that goes to the engine or return line. • High upperdeck pressure will cause the aneroid to contract and increase the amount of fuel available to the engine. • Low upperdeck pressure will cause the aneroid to expanded sending more fuel to the return line. • Why is this important? What would happen if you ran a tank dry at high altitude.
Magnetos • Magnetos receive pressure from the upperdeck to prevent arcing • An inline filter removes contamination and moisture before the air enters the magneto
Environmental • Warm pressurized air is taken from Upperdeck before the Intercooler. • The air is plumbed through the exhaust to increase temperature. • The air pressure from the upper deck is higher then the pressure in the exhaust. This reduces the chance of Carbon Monoxide from entering the cabin from an exhaust leak.
Environmental… • A valve uses ambient pressure and upperdeck pressure to control the amount of hot air available for the heater.
Putting it all Together
Engine Idling on the Ground at Sea Level • Is the wastegate open or closed? • Why? See speaker notes for the answer.
Full Throttle at Sea Level • Is the wastegate open or closed? • Why? • What could cause an overboost when adding takeoff power? See speaker notes for the answer.
Departing Denver International (True of False) • The mixture should be leaned for takeoff to compensate for the higher altitude • False!!! See speaker notes for the answer.
As the Aircraft Climbs Through: • 5,000MSL • 10,000MSL • 15,000MSL • 20,000MSL • 25,000MSL • What happens to the wastegate? • Will the wastegate be fully closed at 25,000MSL? See speaker notes for the answer.
Turbo Limitations
System Limitations • Operating Limitations Speed KIAS Remarks Vne up to 17,500 MSL 201 Never Exceed Vne at 25,000 MSL 171 Vne is reduced linearly from 17,500 to 25,000 Vno up to 17,500 MSL 178 Maximum Structural Cruising Speed Vno at 25,000 MSL 152 Vno is reduced linearly from 17,500 to 25,000 Note: Vno and Vne can be interpolated for altitudes between 17,500 and 25,000. The PFD airspeed tape will change with altitude to reflect the difference in Vne / Vno
System Limitations • Altitude Limits – Maximum Takeoff Altitude…...………..10,000 MSL – Maximum Operating Altitude................25,000 MSL Note: FAR 91.211 requires the use of oxygen below the maximum operating altitude. • Environmental Conditions – Do not operate the aircraft below an outside air temperature of -40 ° C
System Limitations • Flap Limitation – Do not use flaps above………………...17,500 MSL • Power Plant – Avoid continuous operation with the fuel flow set between 30gph and 18 gph with the MP above 26’’ MP Warning: Continuous operation with MP above 26’’ and fuel flow set between 30 gph and 18 gph could lead to engine damage and possible failure. Operation in this area can lead to excessively high cylinder head pressures and temperatures.
Normal Operating Procedures
Preflight • O2 preflight – O2 quantity, requirements and duration tables – Verify O2 flow to each mask/cannula that will be used • Pulse Oximeter – Check saturation levels on the ground and monitor during flight. – Adjust O2 flow to maintain saturation levels above 90% • Cannulas can not be used above FL180 as per FAR part 23. Masks must be worn above FL180. Plan accordingly.
O2 Considerations • Do not use cannulas above FL180 • Passengers should be thoroughly brief on the use of O2 including: – Proper use of masks/cannulas and flow regulators – Recognition and response to hypoxia – Recognition and response to pilot incapacitation • If saturation levels decrease below 90% – Increase to flow of O2 – Increase mask seal around face – Descend to a lower altitude if saturation level can not be maintained above 90%
Normal Procedures • Engine Start – No Change • Taxi – Lean mixture to the X in miXture • Before Takeoff – No Change – Ensure oil temperature is above 100 ° F before run up
Takeoff • Full throttle • Full mixture (for every altitude) • Boost pump on • Monitor MP for overboost – If the MP exceeds 32 inches reduce the throttle below 32 inches of MP Note: Manifold pressure in the yellow arc (29.6 – 32) is normal with full power and no action is required as long as MP does not exceed 32”
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