Engines / Powerplants

ALSO SEE:

• Constant Speed Props / Manifold Pressure
• Multiengine / High Performance / Complex

Aspirated ROT:

• Engine will lose about 3% of its power for every 1,000’ of altitude

Carb heat:

• Carb heat chart.
• Runups in Pilot Tips of the Week.

CHT (cylinder head temperature)

• How fuel flow affects CHT.
• If too high > Enrich mixture / decrease pitch attitude / reduce power / open cowl flaps
• Shock cooling > avoid it by allowing CHT to drop slowly

EGT (exhaust gas temperature)

• Lean to 100°F on rich side of peak EGT for best operation (technique)

Exhaust valve recession - what causes it? (GenAv News)

Jets / Turbofan / Turboprop

• See Multiengine / High Performance.

Leaning +

• ALWAYS RETURN SLOWLY TO FULL RICH BEFORE INCREASING POWER SETTINGS.
• Whenever mixture is adjusted, rich or lean, it should be done slowly.
• Use full rich mixture during take-off or climb below 5K density altitude (Lycoming).
• Anytime power setting is 75% or less at any altitude
• At high altitude airports (> 5K), lean for taxi, take-off, traffic pattern entry and landing.
• How to (Rob Machado)
• Landing at airports < 5K density altitude, adjust mixture for descent, but only as required.  You can't go wrong if you keep the engine running smoothly!
• Before entering pattern, go full rich
• Methods:
• Fixed props: gradually lean mixture until either tachometer or airspeed peaks.
• From a 1969 172 POH, “…the mixture should be leaded as follows:  pull mixture control out until engine RPM peaks and begins to fall off, then enrichen slightly back to peak RPM.
• Controllable pitch props: lean until a slight increase of airspeed is noted.
• Slowly lean mixture until engine becomes rough or until power rapidly diminishes as noted by undesirable decrease in airspeed.  When either occurs, enrich mixture to obtain an evenly firing engine or to regain most of the lost airspeed or engine RPM.
• When leaned, roughness is caused by misfiring due to a mixture which can’t support combustion.  It’s eliminated by slightly enriching mixture.
• With EGT: lean to 100°F on rich side of peak EGT for best operation.
• At all times, caution must be taken not to shock cool the cylinders.  Maximum recommended temperature change should not exceed 50°F per minute.
• FAA on leaning 
• Lycoming on leaning
• Why does the engine run rough when it's lean? Vid 1, Vid 2.

Magnetos:

• Magneto Management (Aviation Safety)

Oil:

• Too warm > Enrich mixture / decrease pitch attitude / reduce power / open cowl flaps

Percent power (RPM):

• We often see references to 75%, 65% or some other percent of max power setting.  It's easy if a pertinent chart/reference has the correlated RPM setting, but many do not.  When there isn't an RPM setting, it is completely frustrating.  For example, if your max RP is 2700 RPM, 75% power is NOT 2025 RPM.  It's actually 75% HP - which makes sense - but how do you calculate that?  It would seem if 2700 was 100% HP, 2025 would give you 75% HP...but it does not.  
• In studying engines and this problem, I've come up with a possible equation to calculate your percentage RPM settings.  I underlined "possible" because I haven't correlated it to every engine.  It goes like this - and it's pretty simple:
• Subtract the percentage from 100, multiply by 10, subtract from MAX
• Example:  75% of 2700 and 65% of 2700
• 100-75 = 25 x 10 = 250.  2700-250 = 2450 RPM (75% RPM)
• 100-65 = 35 x 10 = 350.  2700-350 = 2350 RPM (65% RPM)
• I hope this helps.  This question has bothered me for quite some time and it's a question students ask.

Power settings:

• Four articles from AVweb - "Where should I run my engine?"
• In general, climb, cruise, descent.

Starting engines:

• Avoid these 5 mistakes when you start your engine.
• Lessons on starting a piston airplane engine (great article).
• Priming for a cold start.
• There’s more to starting an airplane engine than luck.
• Zero throttle start.

- FIG -