Presentation on theme: "MMS&TF Piston Engine Seminar By Chad Menne / Malibu Aerospace"— Presentation transcript:
1MMS&TF Piston Engine Seminar By Chad Menne / Malibu Aerospace Teledyne Continental Motors“Gold Motor”Textron Lycoming“Grey Motor”
2Who am I and why are we here? Chad MenneMalibu AerospaceOver 7,000 hours of PA46 timeCorporate flight experienceAircraft managementFlight test experienceEngineering – Research & DevelopmentFAA Certification TestsMaintenance / Production Flight Tests
3Today’s Topics 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?
4Let’s talk engines Reliability “Piston engines are comprised of a thousand parts flying in all different directions, looking for a way out.”
5Let’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.
6Let’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/yearThat 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
7Common Problems Both Malibu & Mirage Exhaust! Magnetos Turbochargers Turbo transitions, slip joints, gaskets, clampsMagnetosCam wear, moisture/corrosion, points, dist. blockTurbochargersDon’t expect them to go to TBOCam & lifter corrosion and wearExcess moisture, fuel dilution, shearing & thermal breakdown of the oil
8Malibu specific problems Exhaust valvesMost common cause from high power & high CHT & exhaust tempsStarter drive adaptersLightweight Iskra starters can cause premature wearAir conditioner driveshaft seals can leakCylinder & ring wearFirst to be blamed & rarely the causeBearing end playCheck for proper end play during pre-flight and DO NOT fly without end play!Borescope for detailed inspection before condemning a cylinderBe sure to use TCM master orifice tool for daily calibration during a compression check
9Mirage specific problems Exhaust valve guide wear (high oil consumption and rough running)Broken oil control ringsPoor break-in results (high oil consumption)Lycoming does not allow mineral oilCracked oil sump at turbo support studsCracked internal oil baffleBe sure to check suction screen for rivetsFuel servo problemsUnable to get proper ground mixture or full power fuel flowCan cause surging in cruiseFuel line AD every 100 hours (cracking due to improper securing of lines)
15Most Common Sources of Wear Metal Elements in Oil IronCylinders, rotating shafts, valve train and any steel part sharing the oil.CopperBrass or bronze parts, bushings, bearings, oil coolers, sacrificial coatings.NickelValve guides, trace element in steel, some cylinder types.ChromiumRings, cylinders, a trace element in steel.SilverSacrificial coatings, a trace element in some types of bearings, bearing cage platingMagnesiumEngine casings, additivesAluminumPistons, piston pin plugs, bearing overlay, casings.LeadPrimarily leaded gas blow-by, traces from bearingsSiliconAbrasive dirt from intake air, silicone sealers and gaskets, sample contamination.TinBearings, bronze parts (with copper), anti-wear coatings.MolybdenumTraces of anti-wear coatings, some cylinder types, and bearings.
28Things that you can doVent 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 compressionDrift down is usually a probe going bad
29The best pilots can juggle The best way to prolong your engine’s life and improve safety is to know how to balance parametersTrade one temp for anotherEngine limits are not intended to provide longest life, but are instead proven to be acceptable for short durationsAdd fuel only as necessary to achieve a good balance during climbLess fuel means more power! (power means heat)
30Which is worse???360° CHT – 1650° TIT400° CHT – 1580°TIT
31Which is worse??? 360° CHT – 1650° TIT 400° CHT – 1580°TIT The TIT is an exhaust gas temp, the CHT affects the engine’s ability to dissipate heatA cooler CHT can transfer more heat away from a valve400° CHT – 1580°TITLess differential from valve to seat and guides removes less heat from valveLocalized oil temps will be hotter at valve guides
32Operations How hot is too hot??? Lean of Peak, no free lunch CHT or EGT/TIT, not both (valve wear)High TIT equals more exhaust wearLean of Peak, no free lunchLose 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)
33LOP Cost Comparison Continental Lycoming 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 hours)1500 hrs x 200kts - 2% / 196kts x $300/hrIncreased exhaust wear costs ($3000 over 2000 hours)Lycoming25% fuel savings ($35,000 over 2000 hours)1500 hrs x 21GPH x $4.50/gal -25%10% speed loss ($50,000 additional cost over hours)1500 hrs x 200kts - 10% / 180kts x $300/hrIncreased exhaust wear costs ($10,000 over 2000 hours)
34Ignition timing and combustion speed How to change your ignition timing???Engine speedHigher RPM = less advance (less time to burn)2500 RPM = 1 Revolution every .024 secondsLower RPM = more advance (more time to burn)2300 RPM = 1 Revolution every .026 seconds or 9% more timeMixture ratio ROPLeaner mixture = more advance (burns faster – sharper power pulse)Richer mixture = less advance (burns slower – softer power pulse)Mixture ratio LOPRicher mixture = more advance (burns faster – sharper power pulse)Leaner mixture = less advance (burns slower – softer power pulse)
35Affects of RPM on “Combustion timing” Lower RPMHigher RPMTDCPeak PressureIntakeCompressionCombustionExhaustEarlier Peak Pressure, More Time to Burn, More Cooling Timeper Cycle, Less HP, Cooler EGT, Cooler CHTTDCPeak PressureIntakeCompressionCombustionExhaustLater Peak Pressure, Less Time to Burn, Less Cooling Timeper Cycle, More HP, Hotter EGT, Hotter CHT
36Affects of mixture on “combustion timing” TDCPeak PressureAffects of mixture on “combustion timing”ROP CombustionLOP CombustionTDCPeak PressureIntakeCompressionCombustionExhaustFaster Combustion, Sharper Pulse, Cooler EGT, Hotter CHTTDCPeak PressureIntakeCompressionCombustionExhaustSlower Combustion, Lower Pressure, Hotter EGT, Cooler CHT
37Leaning Techniques No wonder you’re confused! Rich of peak, lean to peak, lean of peakTIT peak method, a.k.a.“the factory method”Fuel flow methodJPI lean find “Lean L” methodJPI lean find “Lean R” method“The big pull”
38What’s My Horsepower??? Continental Lycoming LOP, FF x 15 = HP ROP, FF x = HP (Can vary a lot)LycomingLOP, FF x 14 = HPROP, FF x 12 = HP (Can vary a lot)