Boosting Your Knowledge of…

TURBO- CHARGING

Randy Knuteson – Analytical / Air Safety

1905 – Patent by Dr. Alfred J. Buchi

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:

1920 – New altitude record in a LePere Bi-Plane – 33,113 feet!

Historical Perspective:

1921 – John Macready's flight to 40,800' in an open cockpit Lusac 11, Lepere biplane.

Turbo-Supercharged B-36

Six 28-Cylinder Engines

Without Turbos – 90 Cylinders per Engine!

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

A TURBOCHARGER IS AN…

…“AIRPUMP” powered by the unused heat energy normally wasted out the exhaust.

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

AME Maintenance Seminar

1650° F

As high as 125,000 RPMs!

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

Bonanza Pilots Turbo Talk

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

4 BASIC SYSTEM COMPONENTS

Turbocharger

Controller

Wastegate

Absolute Pressure Relief Valve (PRV)

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.

TURBOCHARGERS ARE SENSITIVE TO:

Insufficient lubrication

Foreign object damage

Extreme temperatures

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 CONDITIONDoes the shaft spin freely?

VERIFY TURBO CONDITIONWheels should not contact housing.

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

50 and 100 hour inspections:

Inspect the torque on all V-band clamps

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.

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