Constant Speed Props / Manifold Pressure

ALSO SEE:

• Engines / Powerplants
• Multiengine / High Performance / Complex

In General:

• Constant-speed props, adjustable-pitch, adjustable-speed, variable-speed, etc., are called that because you can adjust the RPM and the governor keeps it at that RPM.
• The blue knob (standard color) adjusts the pitch, which in turn adjusts the RPM.
• The black knob (standard) increases/decreases power but the governor tries to maintain the RPM.
• When full forward, the prop gives the highest RPM, but also acts like a brake.
• When full aft, the prop is taking bigger ‘bites’ out of the relative wind.
• IMPORTANT: if your engine fails and you need to glide, pull the prop aft - it’s less drag.
• How a constant speed propeller works.
• How a Piper Seminole constant speed propeller works.

Emergencies:

• First and foremost - always follow your POH
• Need to glide?  Pull the prop full aft when able.  This creates less drag.
• "The Drill"
• PITCH - for blue line
• Mixture (for altitude - it's not binarily forward)
• Props - forward
• Throttles - forward
• Flaps - set
• Gear - up
• Identify AND SLAP your leg
• Verify and pull the throttle back
• Feather
• Mixture - as appropriate
• Engine failure checklist

Governor check:

• I have never seen this described in any POH, but it's a great idea.  After you cycle the prop, pull the prop back until there's a noticeable change (about 100 RPM).  Then gently push up the throttle.  The RPM will increase, but if the governor is working, it should quickly roll back to the starting RPM.  Courtesy:  Steve Jackson

Manifold Pressure:

• Manifold Pressure Sucks (article by AVweb's John Deakin).
• When we talk about RPM and MP (manifold pressure) we drop the zeros off the RPM.  In other words, if we cruise at “22 squared”, we mean 2200 RPM and 22 inches of MP.  Or “21 over 19” would be 2100 RPM and 19 MP.  It’s ‘over’ because we keep the RPM over (or above) the MP.
  

Propeller check:

• The age-old word of mouth (WOM) is to cycle the prop three times.  No POH prescribes it, but it's not a bad idea.  You can watch the RPM, manifold pressure and oil pressure for each cycle.  Additionally, it warms up the oil that drives the propeller change.

Sayings / Expressions / Memory aids:

• Always keep Prop above Throttle (unless POH allows differently).
• When we talk about RPM and MP (manifold pressure) we drop the zeros off the RPM.  In other words, if we cruise at “22 squared”, we mean 2200 RPM and 22 inches of MP.  Or “21 over 19” would be 2100 RPM and 19 MP.  It’s ‘over’ because we keep the RPM over (or above) the MP.
• Blue Sky / Black Earth
• When you add power (go up), you increase propeller first, throttle next
• When you decrease power (go down), you pull the throttle first
• If configuration is Throttle, Prop, Mixture (left to right)
• Gather power up (mixture, prop, throttle)
• Push Power Away (throttle, prop, mixture)
• Pull Power In (mixture, prop, throttle)
• Throw Power Away (throttle, prop, mixture)
• Throttle Back, Power Up
• Reduce the throttle first, Push the Power (Prop) up first

Takeoff:

• Why use high RPM for takeoff with a constant speed propeller? (Vid 226).

More info...

• A graphical approach (youtube)

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Engines / Powerplants

ALSO SEE:

• How does a piston engine work?
• 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): see Temperature below.

EGT (exhaust gas temperature): see see Temperature below.

Emergencies: see Emergencies

Fuel:

• 5 things to look for when you sump your fuel.
• “COWS” (color, odor, water, sediment).  Odor can help if the entire sample is water.
• Quizzes:
• How much does 100 low lead fuel weigh per... 5Qs.
• Unleaded fuel will trash my valves?

Exhaust valve recession: - what causes it? (GA News).

Jets / Turbofan / Turboprop:

• See Multiengine / High Performance.

Knowledge Check/Quizzes:

• Engine parts... What is this part? 6Qs
• On a turbofan engine, what is N1? 6Qs
• What is the Bendix drive part of... 6Qs
  
• What is the primary purpose of the carburetor...7s. (FI)
• You push the throttle full forward... 7Qs.

Leaning: +

• In General:
• Before increasing power settings, return slowly towards full rich .
• 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.
• Why do we do it? (Vid 3).
• Airports (low altitude) < 5K density altitude:
• Adjust mixture for descent, but only as required.  Keep the engine running smoothly.
• Airports (high altitude) > 5K density altitude:
• Lean for taxi, take-off, traffic pattern entry and landing.
• How to (Rob Machado)
• Ground ops:
• How to lean the mixture during taxi to prevent plug fouling.
• Leaning your mixture on the ground. (Vid 16).
• Fuel economy - how to lean the mixture for it. (Flying).
• 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
• Traffic pattern: before entering, go full rich (as required).
• Why does the engine run rough when it's lean? Vid 4 or Vid 207.
• Reference / Articles:
• The fuel air mixture. (AOPA)
• See also Mixture below.

Lycoming:

• How the Lycoming IO-360 works.

Magnetos:

• Magneto Management (Aviation Safety)

Mixture:

• Are you taxiing too rich? (Vid 248).
• How mixture control works on carbureted engines.
• Mixture Magic. J Deakin.
• Why do turbocharged aircraft have a mixture control? (Vid 8).
• See also Leaning above.

Oil:

• 5 things oil does inside your engine.
• 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:

• 5 common mistakes to avoid when you start your engine.
• Hot starts. (ASI)
• How does an aircraft engine start?
• Lessons on starting a piston airplane engine (great article).
• Priming for a cold start.
• There’s more to starting an airplane engine than luck.
• Vapor lock, what is it and why does it happen?
• Zero throttle start.

Temperature(s):

• Four different engine temps, and what they mean to you. (Vid 17).
• CHT (cylinder head temperature)
  • How fuel flow affects CHT. (Vid 15).
  • If too high > Enrich mixture / decrease pitch attitude / reduce power / open cowl flaps
  • Shock cooling > avoid it by allowing CHT to drop slowly
  • Why are my cylinder head temperatures different? (Vid 18).
• EGT (exhaust gas temperature):
  
• Lean to 100°F on rich side of peak EGT for best operation (technique).
• What's EGT used for? (Vid 6, Vid 11 or Vid 80).

Thrust:

• What happens to max available thrust as temperature increases? (Vid 11)

Turbochargers:

• How a turbocharger works.
• Why do turbocharged aircraft have a mixture control? (Vid 8).

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Multiengine / High Performance / Complex

ALSO SEE:

• Constant Speed Props / Manifold Pressure
• Engines / Powerplants

Coffin corner - 6 question quiz.

Jets:

• 5 engine start malfunctions you'll learn about before flying jets.
• Cruise performance (vid).
• How does a turbofan engine work?
• Quizzes:
• On a turbofan engine, what is N1? 6Qs.
• What is N1 on a turbofan engine? 6Qs.
• Where does bypass air go on a turbofan... 6Qs

Multiengine:

• Aerodynamics.
• The “Drill” (emergencies)
• Pitch for Blue Line
• Mixture
• Props
• Throttles
• Flaps set
• Gear up
• Identify and slap your leg
• Verify and pull the throttle back
• Feather
• Mixture
• Engine failure checklist
• Quiz:
• Why is one engine considered critical...5Qs.
• You're flying with an engine inoperative... 6Qs
• You're planning to do your checkride in a Beechcraft... 6Qs.
• Safety Alert: Know when to feather propeller if one engine loses power.
• Staying safe in multi-engine flight. (NAFI).
• Transitioning to multiengine flying? Here’s how.
• Vmc Demo
• Reduce power / lower nose (reduce AOA)
• MULTTI OPS - acronym for determining Vmc
• Maximum takeoff power on operating engine, Unfavorable center of gravity (aft and lateral), Landing gear retracted, Takeoff weight (maximum allowable), Takeoff flaps (in the takeoff position), In trim (for takeoff), Out of ground effect, Propeller windmilling (on the inoperative engine) and Standard day conditions (sea level ISA)

Training:

• Taming the Twin by Air Safety Institute:
• Engine failure during cruise.
• Engine failure during takeoff.
• Intro to multiengine airplanes.
• Single-engine operations.
• Four rules for safe multiengine flying.
• Transitioning to a higher performance aircraft. (AOPA).

Turbochargers: see Turbochargers in Engines / Powerplants.

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