Post on 18-Dec-2015
Historical Perspective:
1910 – G.E. begins manufacturing turbos1915 – First turbo diesel engine
1905 – Sulzer Bros. designs first turbo
1918 – Dr. Sanford Moss altitude tests a 350 hp turbocharged engine.
Historical Perspective:
1921 – John Macready's flight to 40,800' in an open cockpit Lusac 11, Lepere biplane.
ENGINE HORSEPOWER DEPENDS ON…
…The amount of fuel and air an engine burns.
So…actual power is determined by the MASS of air consumed.
…The density of the charge, not the volume.
PRINCIPLES OF TURBOCHARGING
Sea-level air density = 0.0765 lb. cu. ft.At 10,000 ft. air density = 0.0565 lb. cu. ft.
100 hp @ sea-level =
73.9 hp @ 10,000 ft.
A Naturally-Aspirated Engine
WHY TURBOCHARGE?
Power diminishes with an increase in altitude.
Gain more power and increase engine efficiency without enlarging the powerplant.
Recapture the heat energy normally wasted out the exhaust. GOAL – Convert Exhaust Energy into Manifold
Pressure
Exhaust gas inlet (T.I.T.) from the combustion process
Spent exhaust gases overboard
Filteredambient air inlet
Compressor outlet
Routing of exhaust and compressor discharge air
TURBOCHARGING DEFINITIONS
TurbochargingBOOSTED – HP increase (31-45”MAP)
Turbo-NormalizingNORMALIZED – Maintains sea-level
performance (29.5” MAP) at altitude.
TURBOCHARGING DEFINITIONS
Upper Deck Pressure From compressor discharge to the
throttle plate.
Manifold Pressure From the throttle plate to the cylinder
intake port.
AME Maintenance Seminar
Sludge build-up in the “wedge” can decrease the oil pressure feeding into the bearing and shaft
Sludge build-up in the “wedge” can decrease the oil pressure feeding into the bearing and shaft
Piston rings keep air and exhaust pressures out of the center housing
Piston rings keep air and exhaust pressures out of the center housing
30-60 PSI
30-60 PSI
TURBO COMPONENTS:COMPRESSOR STAGE (Cold Side)
Discharge Air
Volute shape – converts velocity energy into pressure energy
Power increasePower
increase
Exhaust volume
increases
Exhaust volume
increases
Turbo begins to spin faster
Turbo begins to spin faster
Increased compressor discharge
Increased compressor discharge
MAP increases
MAP increases
TURBO “RUN-AWAY”
COULD EXCEED MAXIMUM
ENGINE OPERATING LIMITS!
Decrease power
Decrease power
Decreased
exhaust flow
Decreased
exhaust flow
Turbo slows down
Turbo slows down
Compressor
discharge decreases
Compressor
discharge decreases
MAP decrease
s
MAP decrease
s
Upper Deck Pressure
Engine Oil from
Wastegaate Actuator
Aneroid Bellows
Oil restrictor
Valve
Oil Return to Engine
Throttle Controlled Cam
4 BASIC SYSTEM COMPONENTS
4 BASIC COMPONENTS
Wastegate (Exhaust Bypass Valve)Butterfly
Valve
Drain Port
Oil Inlet
Piston
Oil Outlet to Controller
4 BASIC SYSTEM COMPONENTS
Absolute Pressure Relief Valve (PRV)
Escape path for excess Upper Deck
Air Pressure
Valve Face
Spring and Bellows
Assy
Valve Seat
Turbo output pressures must be regulated.
Without a control system, the turbocharged engine would Be extremely unstable.
INSUFFICIENT LUBRICATION…
…RESULTS IN:
Bearing damage that causes an increase in the orbital motion of the turbine shaft.
Turbine and compressor wheels begin to contact their respective housings.
CONTAMINATED LUBRICATION RESULTS IN:
Damage to bearing(s)Collateral damage to turbine and compressor housingsFull floating bearings require 30 PSI minimum at inlet (3 GPM)
Engine Oil should be changed every 25-35 hours in a turbocharged engine.
Lubricating Oil Recommendations:
Lycoming SI 1014M – “All turbocharged engines must be broken-in and operated with ashless dispersant oil only.”
TCM M87-12 Rev 1 – Straight Mineral Oil (MIL-L-6082) may be used – not to exceed 25 hours or 6 months of operation.
VERIFY TURBO CONDITION
Use a light source to carefully examine the
condition of the leading edges of the
Turbine Wheel blades.
Check inducer
blades for damage
FOREIGN OBJECT DAMAGE
Bolts, valves, and rocks will break pieces from the blades or “machine” them down.Abrasive matter (sand, dirt) will wear away the underside of the blades.Soft material (shop rags) will bend the compressor blades backwards.
Avoiding Turbo Oil Leaks
Drain ports must point down. (not more than 35 degrees from vertical centerline) Drain line should slope entire length (no “sink traps”).Check hoses for internal de-lamination.
No sludge at outlet From “coking” of bearing housing.
Restriction or faulty check valve(s)
Overspeed/Overshoot/Overboost
Overspeed
Overshoot
Operating an engine above it’s rated speed or RPM.
Automatic controls can’t respond quickly enough to the inertia of the turbocharger speed as it increases when the throttle is rapidly advanced.
Overspeed/Overshoot/Overboost
Overshoot Lycoming says:
“If overshoot does not exceed 2 inches and 3 seconds duration, it may be disregarded.”
Overspeed/Overshoot/Overboost
OverspeedOvershoot
Overboost Occurs when the manifold pressure
exceeds the limits at which the engine was tested and FAA certified.
OVERBOOST – CAUSED BY:
Rapid throttle movement Exhaust By-Pass Valve fails to open.Sticking WastegateAir in the oil feed to the controllerPRV (pop-off valve) fails to open at predetermined crack point.
“UNACCEPTABLE OVERBOOST”
TCM SB67-12
“OVERSHOOT” / “OVERBOOST”
3-6 INCHES – Check System, Adjust or Replace Malfunctioning Components.
“UNACCEPTABLE OVERBOOST”
LYCOMING MSB-369J
“Not exceeding 5 inches Hg. or 10 seconds” – Normal 50 hour inspection required.
“Not exceeding 10 inches Hg.” – Complete engine disassembly and inspection.
“Over 10 inches Hg.” – Complete engine Overhaul and crankshaft replacement.
“ACCEPTABLE OVERBOOST”
LYCOMING MSB-369J “Momentary” - not exceeding 3
inches Hg. for 5 seconds
Log Book entry required.• Maximum manifold pressure
reached.• Duration of overboost• Cylinder head temperature• Ambient air temperature• Pressure altitude
“ACCEPTABLE OVERBOOST”
LYCOMING MSB-369J
Visual inspection of compressor and turbine wheels
Manually check for excessive movement of turbine shaft in the journal bearings.
Radial Bearing Check
Axial End Play Bearing Check
CHECKING BEARING CLEARANCES
0.003-0.007
0.004-0.009
Maintenance of Turbo System
Preflight – Visual Inspection Check for security of turbo mountings
and connections. Inspect for evidence of oil leakage, air
leakage, or exhaust leakage.
Maintenance of Turbo System
Inspect the hoses and tubing of the air intake system.
Check for leakage due to cracks, damaged gaskets, loose clamps or connections.
Restrictions due to kinks, collapsed hoses, or dented tubing.
Inspect for exhaust leakage.
50 and 100 hour inspections:
Maintenance of Turbo System
Check oil feed and return lines. Unusual noises or vibration. Observe the engine exhaust. FOD damage to wheels or evidence of
contact with housings.
50 and 100 hour inspections:
Turbo Cool Downs
Allow for a two to four minute cool-down period.
CHT – drop 50 degrees from last power reduction
EGTs – 500 degree drop from Cruise Temps.