MMS&TF Piston Engine SeminarBy Chad Menne / Malibu Aerospace

Teledyne Continental Motors“Gold Motor”

Textron Lycoming“Grey Motor”

• Chad Menne• Malibu Aerospace• Over 7,000 hours of PA46 time• Corporate flight experience• Aircraft management• Flight test experience• Engineering – Research & Development• FAA Certification Tests• Maintenance / Production Flight Tests

Who am I and why are we here?

Both Lycoming & Continental Engines How do we operate these engines? Why do we operate them that way? What are we missing? What is my mechanic missing? What are common problems?

Today’s Topics

Reliability◦ “Piston engines are comprised of a thousand parts

flying in all different directions, looking for a way out.”

Let’s talk engines

Reliability◦ “Piston engines are comprised of a thousand parts flying in

all different directions, looking for a way out.”

98 out of 1385 total accidents were due to powerplant failures (7%), representing 21.4Million flight hours (Nall report 2007). That is one accident every 218,367 flight hours caused by engine failures,(turbine & piston). 11 of them resulted in fatalities (0.8%), which equals ONE fatal accident every 1.95Million flight hours due to engine failure. The TOTAL fatal accident rate is 1 per 84,920 flight hours for ALL types of accidents in ALL types of planes.

Let’s talk engines

Reliability◦ “Piston engines are comprised of a thousand parts flying in all different

directions, looking for a way out.”

98 out of 1385 total accidents were due to powerplant failures (7%), representing 21.4Million flight hours (Nall report 2007). That is one accident every 218,367 flight hours caused by engine failures,(turbine & piston). 11 of them resulted in fatalities (0.8%), which equals ONE fatal accident every 1.95Million flight hours due to engine failure. The TOTAL fatal accident rate is 1 per 84,920 flight hours for ALL types of accidents in ALL types of planes.

The piston PA46 fleet averages about 150,000 hours/year That means we should see one accident every 1.5 years and one

fatal accident every 13 years due to engine failure (piston & turbine) Some sources claim a piston engine fails every 3,200 flight hours.

Pratt & Whitney claims a PT6 failure every 333,000 flight hours by comparison

Let’s talk engines

Both Malibu & Mirage◦ Exhaust!

Turbo transitions, slip joints, gaskets, clamps◦ Magnetos

Cam wear, moisture/corrosion, points, dist. block◦ Turbochargers

Don’t expect them to go to TBO◦ Cam & lifter corrosion and wear

Excess moisture, fuel dilution, shearing & thermal breakdown of the oil

Common Problems

Exhaust valves◦ Most common cause from high power & high CHT & exhaust temps

Starter drive adapters◦ Lightweight Iskra starters can cause premature wear◦ Air conditioner driveshaft seals can leak

Cylinder & ring wear◦ First to be blamed & rarely the cause

Bearing end play◦ Check for proper end play during pre-flight and DO NOT fly without

end play! Borescope for detailed inspection before condemning a

cylinder Be sure to use TCM master orifice tool for daily calibration

during a compression check

Malibu specific problems

Exhaust valve guide wear (high oil consumption and rough running)

Broken oil control rings Poor break-in results (high oil consumption)

◦ Lycoming does not allow mineral oil Cracked oil sump at turbo support studs Cracked internal oil baffle

◦ Be sure to check suction screen for rivets Fuel servo problems

◦ Unable to get proper ground mixture or full power fuel flow◦ Can cause surging in cruise

Fuel line AD 2008-14-07 every 100 hours (cracking due to improper securing of lines)

Mirage specific problems

Believe it, or not!

Lifter Main bearing

Crankcase bearing journal

Crankshaft Bearing Wear

Oil Sample - Good

Oil Sample - Bad

Iron Cylinders, rotating shafts, valve train and any steel part sharing the oil. Copper Brass or bronze parts, bushings, bearings, oil coolers, sacrificial coatings. Nickel Valve guides, trace element in steel, some cylinder types. Chromium Rings, cylinders, a trace element in steel. Silver Sacrificial coatings, a trace element in some types of bearings, bearing cage plating Magnesium Engine casings, additives Aluminum Pistons, piston pin plugs, bearing overlay, casings. Lead Primarily leaded gas blow-by, traces from bearings Silicon Abrasive dirt from intake air, silicone sealers and gaskets, sample contamination. Tin Bearings, bronze parts (with copper), anti-wear coatings. Molybdenum Traces of anti-wear coatings, some cylinder types, and bearings.

Most Common Sources of Wear Metal Elements in Oil

Exhaust Woes

Leaky Gasket Colorful clues

Mirage Turbo Transition

Heavy, Cast Inconel Erosion & Blistering

Malibu Turbo Transition

.065” Stainless Steel Check at EVERY Oil Change!

Tailpipe Trouble

Corrosion has its way Heat Muff - Uncovered

V-Band Clamps

Exhaust Clamps

Malibu & Old-Style Mirage Clamps Crack from over-tightening

Exhaust Clamp Engagement

The right way The WRONG way

Sump Cracks (Turbo Mounts)

Turbochargers

Compressor damage Bearing failure Seal failure Scavenge pump failure Scavenge hose failure Wastegate failure or sticking

Common Turbo Problems

Turbochargers

Bearings Compressor Damage

Engine Cooling

Vent oil cap after shutdown (minimize corrosion)

Watch EGTs and trend data (ignition and fuel injection anomalies)

In-flight mag checks (look for hot or cold EGTs) Oil samples (watch for iron, nickel,

almuminum) Watch for peak TIT drift (up or down)

◦ Drift up is usually ignition or low compression◦ Drift down is usually a probe going bad

Things that you can do

The best way to prolong your engine’s life and improve safety is to know how to balance parameters◦ Trade one temp for another◦ Engine limits are not intended to provide longest

life, but are instead proven to be acceptable for short durations

◦ Add fuel only as necessary to achieve a good balance during climb Less fuel means more power! (power means heat)

The best pilots can juggle

A. 360° CHT – 1650° TITB. 400° CHT – 1580°TIT

Which is worse???

A. 360° CHT – 1650° TIT◦ The TIT is an exhaust gas temp, the CHT affects

the engine’s ability to dissipate heat◦ A cooler CHT can transfer more heat away from

a valveB. 400° CHT – 1580°TIT

◦ Less differential from valve to seat and guides removes less heat from valve

◦ Localized oil temps will be hotter at valve guides

Which is worse???

How hot is too hot???◦ CHT or EGT/TIT, not both (valve wear)◦ High TIT equals more exhaust wear

Lean of Peak, no free lunch◦ Lose speed (less power at same power setting)◦ Wear exhaust (higher EGTs, more oxidation)◦ Not as smooth (slight roughness or surging)◦ Cooler CHTs (helps offset the higher EGTs and cool

valves)

Operations

Continental◦ 20% fuel savings ($28,000 over 2000 hours)

1500 hrs x 21GPH x $4.50/gal - 20%◦ 2% speed loss ($9,000 additional aircraft cost over 2000

hours) 1500 hrs x 200kts - 2% / 196kts x $300/hr

◦ Increased exhaust wear costs ($3000 over 2000 hours) Lycoming

◦ 25% fuel savings ($35,000 over 2000 hours) 1500 hrs x 21GPH x $4.50/gal -25%

◦ 10% speed loss ($50,000 additional cost over 2000 hours) 1500 hrs x 200kts - 10% / 180kts x $300/hr

◦ Increased exhaust wear costs ($10,000 over 2000 hours)

LOP Cost Comparison

How to change your ignition timing???◦ Engine speed

Higher RPM = less advance (less time to burn) 2500 RPM = 1 Revolution every .024 seconds

Lower RPM = more advance (more time to burn) 2300 RPM = 1 Revolution every .026 seconds or 9% more time

◦ Mixture ratio ROP Leaner mixture = more advance (burns faster – sharper power

pulse) Richer mixture = less advance (burns slower – softer power pulse)

◦ Mixture ratio LOP Richer mixture = more advance (burns faster – sharper power

pulse) Leaner mixture = less advance (burns slower – softer power

pulse)

Ignition timing and combustion speed

Lower RPM

Higher RPM

Affects of RPM on “Combustion timing”

Earlier Peak Pressure, More Time to Burn, More Cooling Time per Cycle, Less HP, Cooler EGT, Cooler CHT

Later Peak Pressure, Less Time to Burn, Less Cooling Time per Cycle, More HP, Hotter EGT, Hotter CHT

Intake Compression Exhaust

Intake Compression Combustion Exhaust

Combustion

TDC Peak Pressure

TDC Peak Pressure

ROP Combustion

LOP Combustion

Affects of mixture on “combustion timing”

Faster Combustion, Sharper Pulse, Cooler EGT, Hotter CHT

Slower Combustion, Lower Pressure, Hotter EGT, Cooler CHT

Intake Compression Combustion Exhaust

Intake Compression Combustion Exhaust

TDC Peak Pressure

TDC Peak Pressure

Rich of peak, lean to peak, lean of peak TIT peak method, a.k.a.“the factory

method” Fuel flow method JPI lean find “Lean L” method JPI lean find “Lean R” method “The big pull”

Leaning TechniquesNo wonder you’re confused!

Continental◦ LOP, FF x 15 = HP◦ ROP, FF x 13.25 = HP (Can vary a lot)

Lycoming◦ LOP, FF x 14 = HP◦ ROP, FF x 12 = HP (Can vary a lot)

What’s My Horsepower???

Questions Comments E-mail me,

cwmenne@malibuaerospace.com Fly Safe!

Thank you!