Engines

Question 1

Monitoring engine performance numbers

Answer 1

During climb cruise and dissent. For baseline values and make it easier to notice anomalies are trends in the future

Question 2

General rule for amount of oil

Answer 2

Start a flight with at least 2/3 capacity and ensure you finish a flight with at least half capacity

Stick to the more restrictive POH limitation

Question 3

Hi oil temperature was low oil pressure

Answer 3

Precautionary landing no matter how much oil you think you have

Question 4

Oil that gets dirty early in life

Answer 4

Could be sign of other problems like excessive piston ring blow by

Question 5

Wear gloves during a fuel inspection

Answer 5

Gasoline and lead are bad for skin

Question 6

Things to look for when doing fuel check on sump

Answer 6

Flow rate between two sides – possible corrosion in valve or debris

Color – 100LL Blue. Clear is jet A. Drop of fuel on a paper towel Pier 100 LL evaporates quickly and dries clean. Jet A leaves behind a greasy ring

Water-allow 15 minutes after fueling before sumping to allow water to collect at the drain

Sump on a level surface

Question 7

Parking overnight in humid area

Answer 7

Fuel the tanks. Always sump after parking overnight even if you didn’t add fuel

Question 8

Distance from the fuel pump

Answer 8

Signified by yellow arc on ground Shows how far the hose will reach

Question 9

Av gas is a terrible conductor true or false

Answer 9

True. The resulting spark from buildup of static charge as fuel flows can ignite the fuel. Aircraft needs proper grounding Between fuel components and the airplane

Question 10

Fuel cap rules to live by

Answer 10

Securely in your hand or

securely in place

Cap goes on as soon as fueling is done

Question 11

Inserting fuel nozzle into tank

Answer 11

Only so far to ensure if you will go in. Too far and you can damage fuel tanks cell or liner or hit a fuel level sensor

Question 12

What is quenching

Answer 12

Slower airflow gives fuel in the carburetor more time to drop out of the air and pool on the metal intake manifold of the carburetor

Will occur on the first start. will need priming to overcome

Question 13

Over priming causes what?

Answer 13

An over rich mixture

Pool is too big, the mixture to Rich, and ignition is impossible until the pool shrinks

As fuel is atomized it eventually hits the right amount and combustion in cylinder occurs

Question 14

Under priming

Answer 14

Start out too lean, just gets leaner as you crank so under priming is useless

Question 15

Throttle is too far closed on start

Answer 15

Engine never gets lean enough to start a.k.a. it floods

Question 16

Flooded engine start

Answer 16

Mixture – idle cut off

Crank engine while…

Opening throttle such That it would take about 10 seconds to reach wide-open

No rush to get the mixture control back in. Engine will run for a couple seconds on the fuel sitting in the intake. If it quits you’ll have rectified the flooding anyway

Fuel also will eventually evaporate

Why not crank just a little longer? Mixture would get leaner as you crank but your starter would overheat and your battery would be dead

Question 17

When can you try starting with the throttle closed?

Answer 17

Engine is warm from previous flight, or summer day.

Throttle closed
While engine cranking, throttle about halfway, then rapidly back to full closed. To rich slightly

Main reason to have the throttle cracked normally is that cold engines don’t idle well

Question 18

What is an accelerator pump

Answer 18

Squirts a burst of fuel into the car but every time you open the throttle so the engine doesn’t go over lean and stumble at the moment after the throttle opens

If your plane has this, consider not pumping the throttle until the engine is cranking. Could pool fuel and cause a fire before starting

Question 19

Way to avoid spark plug fouling at idle speed

Answer 19

Lean the mixture as aggressively as you can after the engine starts.

Lean until engine RPM rises

then continue until RPM Falls but not so much of the engine stumbles are quits

Cold engine needs extra fuel at idle during first few minutes of operation

Will need to go for Rich before takeoff again.Make sure included in checklist

Question 20

Carbon fouling of the spark plugs caused by?

Answer 20

Mixtures that are too rich to burn or

mixtures that are so lean they cause intermittent firing

• improper idle mixture adjustment,
• leaking primer, or
• carburetor malfunctions that cause too rich a mixture in the idle range

Rich mixture detected by soot or black smoke coming from exhaust or by increase RPM when the idling fuel air mixture is leaned to best power

Question 21

Oil fouling of spark plugs

Answer 21

At low engine speeds oil combines with sought in the cylinder to form a solid that can short out the spark plug.

Oil that has been service for any length of time holds in suspension minute carbon particles that are capable of conducting electricity

Higher RPM carries away excess oil

Question 22

Lead fouling of spark plugs

Answer 22

Lead from fuel forms lead oxide during combustion in deposits on combustion chamber surfaces.

Also good electrical conductor at high temperature and causes miss firing

Most conducive wall cruising with lean mixtures.

Lead build up generally confined to specific combustion temperature range

Can usually be eliminated by increasing combustion temperature… Operating engine at full takeoff power for one minute

Question 23

Graphite fowling

Answer 23

Excessive application of lubricant anti-seize compound to the spark plug. Causes shorting because graphite is good electrical conductor.

Never apply lubricant to the first set of spark plug threads. Do not contact the electrodes

Question 24

Rough running as a lean for taxi might indicate what?

Answer 24

Induction leak

Leak of air getting into the engine other than past the throttle means engine is to lean at idle

Question 25

What does the mag check check?

Answer 25

Entire ignition system: magnetos, wiring harnesses, spark plugs, ignition control switch (key) CHT should change very little Check R magneto first (disables left) Wait for RPM stabilization

Question 26

Mag check: expected RPM drop and smooth engine? (Option 1 of 4)

Answer 26

EGT rises CHT steady or slight drop because single spark is less effective at initiating combustion, so fuel is burning for a longer period of time and further into the cycle of the piston EGT falling Means active spark plug (one driven by active mag) in that cylinder is not performing correctly. Can cause roughness but not always (especially six cylinder engine’s). Attempt to clear using fouled plug procedures, then test mag again. If not plug itself, Could be the wiring harness, or terminal on the magneto CHT- note all CHT downward trends over next minute, and keep in mind for next mag check

Question 27

Mag check: excessive drop in RPM and smooth. (Option 2 of 4)

Answer 27

Excess drop, and smooth with Accompanying rise in all EGT: Retarded timing in the active magneto. This robs you have total engine power and should be checked by mechanic. Check the other mag before taxing back

Question 28

Mag check: rough regardless of the drop (option 3 of 4)

Answer 28

Denotes uneven power distribution Check EGT. If EGT fallen, likely a mag problem Could be such retarded timing that combustion is failing intermittently, but unusual. More likely has a problem with ignition in specific cylinders. Look for cylinders with excessive EGT drop. May indicate that no combustion is happening there. First try clearing a fouled plug. If that doesn’t work go back to ramp with mag to plug chart in hand for troubleshooting

Question 29

Mag check: absence of change (option 4 of 4)

Answer 29

No RPM drop, no EGT rise. Probably switch itself or some other part of the ignition grounding system Could be advanced timing on current mag. Especially if accompanies CHT drop on other mag

Question 30

True or false timing of the spark for magnetos differs based on the engine speed

Answer 30

False. Engine spark timing is optimized for max RPM were getting most power is critical Time to so that the flame front and expanding hot gases meet the top of the cylinder just as it’s descending.

Question 31

Retarded timing causes

Answer 31

Engine doesn’t produce full power

Question 32

Advanced timing causes

Answer 32

Pressure inside cylinder can rise to damaging levels and CHT can go off the charts. Can cause engine failure in minutes if really off If you ever see a situation Like this after engine maintenance, taxi back to the ramp and get timing rechecked

Question 33

Carb heat RPM drop on run up Too little dip could signify

Answer 33

100-200 rpm drop on runup Too little (<100, check to see if working as designed. Some aircraft only do do that much) possible indication of fresh air leaking into that system or incomplete closing of the carb heat door (check to see if knob is still 1/8” from the panel when fully closed) *key is know what to look for every time

Question 34

Carb heat warm air into the intake reduces the available power (up to 15%) from the engine for three reasons:

Answer 34

1) thermodynamic efficiency is slightly reduced, since it is a function of the difference in temperature between the incoming and exhaust gases; 2) quantity of air available for combustion inside the cylinders is reduced due to the lower density of the warm air; 3) the previously-correct ratio of fuel to air is upset by the lower-density air, so some of the fuel will not be burned and will exit as unburned hydrocarbons.

Question 35

Landing checks O-B-U-M-M-M-P-F-F-I-T-C-H-H

Answer 35

``` (*Comm-ATIS/Tower) O - Open carburettor heater B - Brakes free U - Undercarriage down and locked M - Mixtures M - Magnetos M - Master switch P - Propeller Pitch F - *Fuel [Selectors both, mixture rich] F - *Flaps I - Instruments (*Lights) T - Temperatures and pressures C - *Close carburettor heat H - Hatches or doors H - *Harnesses ```

Question 36

If filtered air gets blocked what could you do?

Answer 36

Use carb heat as a backup source

Question 37

When should you check standby vacuum systems?

Answer 37

Same time you check carb heat

Question 38

What are you checking for the load test

Answer 38

Ensure your battery can recharge and supply power to everything at the same time Turn on all lights, pitot heat, prop heat. Obey any prohibitions for hot items on the ground like windshield heat Check voltage and ammeter While the system is under load. Shouldn’t drop out of range except for momentary drop from Beacon flash Normal voltage for 12 V system is usually 13.5 to 14.5 when the alternator is running. If system can’t supply max power without the battery helping get it checked out.

Question 39

Possible issues associated with the readings slightly out of the green

Answer 39

Slightly low vacuum could be a leak that will worsen and could damage an instrument Slightly off oil or coolant temp could be a winterization kit (restricts airflow over cylinders to keep temp higher quicker and longer) that someone forgot to remove on the weather turned warm.

Question 40

How to clear a fouled plug

Answer 40

Don’t pick a spot over sand or a puddle Point into the wind (engine heat is good, high CHT does nothing) Magnetos- both Engine power~ 65% (~2300rpm) Lean the mixture for peak RPM (EGT if have engine monitor) Run for 45-60s Watch CHTs for nearing limits. If do, reduce power End of timer, reduce power to normal runup RPM, Richen mixture, and check each mag again. look for smooth operation If better but not fixed, you correctly identified the problem. Don’t try this more than TWICE. If still not cleared then have to clear manually or fouling isn’t the culprit. Taxi back to ramp.

Question 41

Other common issues with spark plugs besides fouling

Answer 41

Wire chafing. Spark plugs won’t fire if the wire is grounding to the air frame. Possible the problem is where the leads connect to the towers on the magneto itself. Best left to a mechanic. Corrosion or possibly the magneto itself

Question 42

Pre-takeoff instrument check

Answer 42

REACT: ``` RPM ENGINE GAUGES AIRSPEED CENTERLINE TAKEOFF ABORT POINT ```

Question 43

Pre-takeoff RPM check

Answer 43

Fix pitch prop look for the correct static RPM My only showed 2300 RPM at full power until the airplane starts moving where Forward motion lowers the props angle of attack, making it easier for the spin Anything less than expected indicates engine isn’t producing full power. Abort the takeoff to troubleshoot

Question 44

Takeoff engine instrument and fuel flow check

Answer 44

Low oil temp on a winter day not cause for concern immediately. Low oil pressure at full power might not be a cause for a board, but worth watching that it doesn’t get lower during flight Worth knowing specific fuel flow. Some airplanes have a chart for determining specific fuel flows on takeoff. Might need to lean in order to hit that number

Question 45

Thumb rule for determining take off fuel flow

Answer 45

Sea level horsepower divided by 10 for aircraft up to 200 hp. Divide by 11 for over 200 hp To correct for higher altitudes (and you don’t have a turbo), reduce rated horsepower by about 3.5% for every 1000 foot increase in pressure altitude. Also applies if leaning for high-altitude takeoff I.e.) 6000 feet DA, fuel flow would be 82% of what you normally see at sea level

Question 46

Common POH recommendation for altitude for leaning engines

Answer 46

> 3000 feet for Lycoming engines

Question 47

Which altitude should be used for referencing to lean for high altitude takeoff

Answer 47

Density altitude

Question 48

How to determine density altitude

Answer 48

Set altimeter to 29.92 Read altitude from the altimeter Add or subtract 120 feet for every degree C above or below standard temperature for that pressure altitude

Question 49

Leaning for high altitude takeoff

Answer 49

Full rich Advance throttle to full takeoff power Lean, watching the tachometer RPM should rise as you approach the best power mixture and then begin to fall as you get too lean Moment RPM begins to fall, note the mixture control position and re-enriching to a point halfway between Max RPM and full rich

Question 50

Leaning for high altitude takeoff (DA so high that engine can't produce >65%)

Answer 50

Full rich Advance throttle to full takeoff power Lean, watching the tachometer RPM should rise as you approach the best power mixture and then begin to fall as you get too lean Set mixture control to peak to get as much power as you can (Unlikely though since that would mean ~11k DA, but is this even a takeoff you'd like to attempt??. Wait for cooler weather instead)

Question 51

If the pilot believes the engine may be detonating, he or she could take the following actions.

Answer 51

1) Increase the engine mixture. 2) Reduce power to a lower setting. 3) Reduce or stop climb and increase forward speed for greater cooling.

Question 52

Leaning at high power risks what?

Answer 52

Causing detonation

Question 53

What is altitude compensation in fuel delivery system

Answer 53

Some aircraft automatically adjust baseline fuel flow for pressure altitude, so you can take off at full throttle and full rich for all altitudes. Pilot still needs to lean for cruise at altitude

Question 54

Some magnetos connect their p-leads through a capacitor. What happens if it fails?

Answer 54

Acts like a broken p-lead, and could have a hot mag still.

Question 55

Carbureted and some injected engines experience a rise in RPM when idle cutoff. Why and how much RPM is normal or of concern?

Answer 55

25-100 RPM: normal >200 RPM: idle mixture setting too rich fuel flow can't be consistently delivered at low RPM, so they have other systems that measure fuel for idle.

Question 56

Over-rich mixture in climb causes what?

Answer 56

slower climb rate and wasted fuel

Question 57

How to lean during climbout

Answer 57

If EGT readouts: as takeoff EGT falls when you increase altitude, lean just enough to maintain that takeoff EGT. If normalize feature, normalize ASAP after rotation, then maintain 0 EGT. Or use fuel flow read out, make your own schedule. reduce SL fuel flow by 3% for ea 2000' altititude gain.

Question 58

How to double check if your Automatic Altitude compensation for leaning is working?

Answer 58

Check fuel flow against expected for your current altitude.

Question 59

How to set mixture for takeoff (only recommended w/multi probe EGT)

Answer 59

1) foot on brakes 2) Full rich, apply full throttle power 3) Lean referencing your leanest cylinder (first to reach peak EGT) **Once you know how much the system lags, you can do it quickly to minimize the time spent at full power without accompanying cooling airflow

Question 60

Why is it not a good idea to climb at best rate of climb speed all the way to cruise

Answer 60

Because airspeed improves engine cooling and forward visibility with only a small hit to climb rate

Question 61

What is an economizer circuit in a carburetor?

Answer 61

Throws more fuel into the carburetor at wide-open throttle

Question 62

What is the most efficient altitude for fixed pitch prop aircraft

Answer 62

The altitude where you can get the power setting you want at wide-open throttle. Typically 5 to 8000 feet for 65 to 75% power

Question 63

What should minimum CHT be and why do you keep it that way?

Answer 63

Running the engine cooler is not always desirable because it causes build ups on the valve and valve stems

Question 64

What is your maximum no wind speed, generally speaking

Answer 64

The highest altitude (highest true airspeed) where you can produce max continuous power. With a turbo charger that’ll be close to your critical altitude. Without one, not very high

Question 65

Extended low power with a full rich mixture can lead to what?

Answer 65

Lead deposits on the valves. Only at low altitude. At higher density altitude you must Lean for takeoff and lean for climb

Question 66

What is the “do no harm” approach to leaning the engine?

Answer 66

Use your POH to find what RPM setting produces 65% power for your cruise altitude. At that power setting it’s almost impossible to damage an engine with leaning.

Question 67

In the Cessna, how to set lean at 65% cruise?

Answer 67

With a fuel flow gauge, just lean to that fuel flow for that 65% power setting (including altitude and temperature compensation). Without a fuel flow gauge lean until the engine begins to run rough and then enRich in until it’s running smoothly again

Question 68

In the Cessna, how to sit lean at greater than 65% power?

Answer 68

Set fuel flow if you have fuel flow gauge. But consider using 10% more fuel flow then published at greater than 65% because manufacturer fuel flows may provide a little or no margin against engine damage at higher power Without a fuel flow gauge, lean until engine roughness (do this such that it takes no more than 10 seconds to reach this rough point). Note the position of the mixture control, then reenrichen to a point halfway between rough running setting and full rich. Results in more fuel then you need to burn, but should be safely on the Rich side

Question 69

Why does the engine produce more power even though there’s less fuel as we lean

Answer 69

Because we’re generating more heat and pressure as that fuel burns more efficiently.

Question 70

Will choosing a lower power cruise setting make An engine last longer?

Answer 70

Continuous maximum power is just that: you can fly at that power setting indefinitely. Unlikely to have an appreciable difference on life. Any value of horsepower per cube (horsepower divided by displacement in cubic inches) of .6 or greater: conservative power settings might extend the life.

Question 71

LOP power calculation

Answer 71

15 times fuel flow in gallons per hour. = HP Then divide by total rated horsepower for the power setting (Percentage power on an EGT monitor is usually based off ROP calculation, and is incorrect if running LOP. Some monitors have lean assist that also based off of ROP calculations) many systems also used a fixed number of degrees ROP or LOP as a target, rather than an adaptive number based on power

Question 72

The higher your power setting, the further ______ or ______ you must be to stay safe

Answer 72

ROP or LOP EGT The spread between safe ROP and safe LOP can be quite wide

Question 73

Job when leaning is targeting a _______ or ________.

Answer 73

Safe best power somewhere ROP OR Safe best efficiency somewhere LOP

Question 74

Many POHs recommend ________ for best power. The highest ____/______ is in that zone is the most likely zone for _________to occur. That’s why many POH recommend peak EGT for _________.

Answer 74

50-100°F ROP ICP/HP Engine damage Economy

Question 75

The higher the engines rated power for its size (HP per cubic inches) the__________ you must be to be safe.

Answer 75

Further ROP or LOP you must be to keep your engine safe

Question 76

Operations between minimum ROP and minimum LOP (danger zone) should be limited to no more than______

Answer 76

a minute

Question 77

Difference between running at min ROP and min LOP

Answer 77

Lean Burns less fuel and puts less fuel and less carbon in the oil and spark plugs. Both yield same airspeed and similar CHT

Question 78

To safely operate LOP you would need

Answer 78

Fairly even fuel distribution between all cylinders Which never happens. The greater the difference in power between the cylinders the tougher the engine runs Because the power drops off faster on the lean side of the curve....

Question 79

Both the extreme ROP and extreme LOP yield the same power, but the lean one __________. The down side of running LOP is_______.

Answer 79

Burns less fuel and puts less carbon in the oil and in the spark plugs. Not everyone can run LOP smoothly

Question 80

Unless the difference between your richest and leanest cylinders (GAMI spread) is less than _______, you can’t run _____ of peak. GAMI spread or fuel distribution can be tested in flight

Answer 80

0.5 GPH Lean *The more cylinders you have, the bigger the problem will be.

Question 81

Virtually no horizontally opposed six cylinder carbureted engine can smoothly run ______.

Answer 81

LOP So check how far ROP you can safely lean to stay safe

Question 82

Leaning to LOP using multi EGT

Answer 82

1) big pull: pull til runs rough, then push back in slightly so it doesn’t quit

Question 83

What to do if Oil temp or CHT are too high during climb?

Answer 83

First, use airflow (airspeed). Second, if not enough, enrichen the mixture (fuel has ~30% of cooling effect of engine, and will cool assuming you're not increasing from Lean of Peak LOP) * *climb performance will suffer, and use more fuel * *No need to lean excessively during clim, as long as climbing on rich side of peak. Third, could also reduce climb power

Question 84

If CHT's are routinely high in climb, could mean what?

Answer 84

engine baffles are not in good shape, or that high power fuel flow is correct Advance timing could cause high CHTs

Question 85

Calculate fuel flow to expect LOP for different percent power setting

Answer 85

1) Calculate horsepower. 300 Hp * 70% power = 210 Hp 2) divide by 15. 210/15= 14GPH After leaning to LOP, verify the delta between Peak EGT and current EGT on richest cylinder is large enough to stay out of danger zone -OR- Go directly from ROP to fuel flow for the power setting you want, and verify EGT delta is sufficient

Question 86

The contact between cylinder wall and piston due to rapid heating and uneven expansion between steel and aluminum is called _______. For this reason, you should ________.

Answer 86

Scuffing Allow your engine to warm up sufficiently before even applying run up power

Question 87

LOP operations usually require a GAMI spread of less than _____. Some carbureted six cylinders can have GAMI spreads of up to _____, which is why LOP operation is essentially impossible. Sometimes GAMI spread can be reduced in carbureted engines by ______ & _______.

Answer 87

1 GPH 2 GPH Operating with the throttle just slightly closed & Judicious use of carb heat

Question 88

Lean range is the difference between ____ &______. GAMI spread is difference in ______&_______.

Answer 88

EGT @ full rich & peak EGT Fuel flow when richest cylinder reaches peak EGT & Fuel flow when leanest cylinder reaches peak EGT

Question 89

O300 manual) Due to design in today’s higher output engines, the comparison of ____ versus _____ is no longer a sound criteria for evaluation of magnetos. Therefore all magneto checks should be compared between _________. Difference between the two should be _____. Oil pressure should _______. Magneto drops of up to ______ are not uncommon but if the cylinder is not firing __________ will be very evident and magneto drop will be considerably greaterz

Answer 89

Single magneto VS both magnetos, 75 RPM, Slightly rise Between left and right magneto 150 RPM, Engine roughness