private pilot ground school Articles | Index    

Operation of Airplane Systems
2010-03-18

Operation of Airplane Systems

REFERENCES: C 61-21, AC61-23, Airplane Handbook and Flight Manual

P 1. Explain aircraft systems and operation.

Ex Controls, flaps, trim, engine, instruments, landing gear, engine, propeller, fuel system, hydraulic system, electrical system, environmental system, icing, navigation and communications, and vacuum system.

The ailerons, elevators, and rudder are usually moved via a system of cables and pulleys connected to a yoke or stick. In some instances a system of push rods may be used. Flaps and spoilers may be operated by push rods or electrically. Trim may be manual, electrical or both. High performance aircraft may have hydraulic or electric boost systems to aid the pilot.

Flight instruments have several modes of operation. The compass is magnetic. The ball is gravitational and inertial. The needle or turn coordinator is usually electric gyro driven. The attitude and heading indicators are usually gyro driven by vacuum pressure. The altimeter, airspeed indicator, and vertical speed indicator are functions of outside air pressures. Examiners have been known to cover or otherwise disable instruments.

Landing gear, fixed or retractable, have shock absorbing springs, air/oil struts, or rubber in combination to take the shock of landing. Retractables may operate manually or electrically with visual or lighted indicators as to gear position. Higher insurance and maintenance costs go with retractables.

Brakes are usually hydraulically operated shoes clamped to the brake disk attached to the wheels. Hydraulic cylinder connected to the top of the rudder pedals allows toe pressure to operate the brakes. Retractable gear has similar braking systems. Aircraft tires are usually of natural rubber and have a four-ply rating but only two plies. This means that when you can see the beginning of cord in a tire it is absolutely time to quit using it. The nose wheel regardless of its suspension system allows the application of foot pressure on pedals and brakes to provide ground steering. Good operational techniques would use the nose wheel only during the very slowest part of takeoff and landing.

Most light aircraft engines are four stroke, (intake, compression, power and exhaust), horizontally opposed, and gasoline fueled. Each cylinder has a spark plug on top and bottom, which obtain an igniting, spark from dual magnetos. Each cylinder has an upper and lower spark plug. The magneto serving the top right plugs services the lower left plugs.

Spark plugs fouling from fuels with lead would be caused at low power settings where the internal cylinder temperature was not high enough to vaporize additives. Small lead pellets would form in the lower plugs and cause preignition. When unleaded fuels are used the deposits are calcium like particles that cause preignition (knocking in automobiles) by shorting out the spark plugs. Avoid low power descents and power off operations. During taxi be assure to lean so as to avoid lead fouling. At shut down the rpm may be increased momentarily so as to facilitate removal of any accumulated fouling. Preignition is shown by engine roughness, backfiring and high cylinder head temperatures. Detonations occur as a result of ignition of unburned combustible material by pressure or temperature.

1. Copper runout or lead fouling = excessive heat;
2. Carbon and lead bromide deposits = low temperature and excess richness.
3. Oil fouling shows piston ring problems and wear.
4. Other than brown/gray deposits = incomplete combustion
5. Cracked porcelain = preignition
6. Carbon fouling = valve guide or ring wear and oil burning.

The controls for the engine are few. The throttle moves a wire connected to the butterfly valve of a carburetor engine and controls the airflow drawing fuel to the engine. Pumping the throttle can fill the carburetor as a priming method. Over use of this priming can cause the fuel to over flow and start an engine fire. The fuel injected engine throttle performs a similar function but provides better fuel distribution. A fuel-injected engine cannot be primed by pumping the throttle.

The venturi effect of a carburetor air intake can cause any moisture in the air when mixed with fuel to form ice and adhere to the interior of the venturi. This ice can choke off the flow of air to the carburetor. This is most likely to occur at low power settings but can occur at any time even on very warm days. The symptoms of carburetor ice are insidious but start with unexplained loss of RPM or manifold pressure accompanied by roughening engine operation. Since this condition arises from conditions outside the aircraft, correction rather than prevention is the control method.

Application of carburetor heat opens a diversion gate in the heater- exhaust system and cuts off the outside air intake while diverting hot air into the carburetor. The hot air causes an additional drop in RPM or manifold pressure and a rise as the ice melts. Removal of carburetor heat will give an additional rise in RPM and manifold pressure. Fuel injected engines do not have carburetor heat controls.

Air and fuel are mixed by weight. About 16 pounds of air to 1 pound of fuel gives best power. An engine can intake only so much air depending on the volume of its piston cavity. As the density of the air decreases with altitude the air molecule intake into the engine decreases. The 16 to 1 air fuel ratio becomes over-rich with fuel and power decreases. The mixture control allows the pilot to adjust the air/fuel mixture for the best power for the air available. Even so the power of a normally aspirated engine decreases with altitude. It is possible to install an air pump called a turbocharger which will pressurize the air being taken into the cylinders and make possible more fuel consumption and greater power.

Most light aircraft have a fixed pitch propeller, which is a compromise pitch between a climb or cruise propeller. A constant speed propeller has an additional cockpit control, which allows the pilot to use oil from the engine to adjust the pitch for best climb or cruise. The setting of the control causes the propeller to maintain a constant RPM.

The airplane can operate much like a lawn mower. Just turning the propeller can give the electrical spark needed for operation. It is this feature which makes ground operation so dangerous. A shorted magneto or fuel left in the carburetor could cause any small movement of the propeller to start the engine. For these reasons the engine shut down should include a magneto check and fuel starvation. The checking of the magnetos prior to takeoff should be as recommended in the POH (Pilot's Operating Handbook). Checking at a lower RPM may cause a higher than normal magneto drop, giving a false indication of trouble. A minimal or nonexistent drop should raise suspicions of a "hot" or shorted magneto. Hot magneto checks should be done at RPMs less than 800. A momentary turn to "off" should show whether the engine is going to stop (as it should) before returning to "both".

Gasoline is the fuel for airplanes. The fuel is enclosed in metal or rubber tanks, which have cockpit gauges to indicate either weight or quantity. The safest method to judge fuel is by time. All low wing aircraft have electric fuel pumps as a backup for the engine driven pump. High wing aircraft do not usually have auxiliary pumps since the gravity flow is considered adequate. All aircraft have a cockpit operated shutoff valve for gasoline to the tanks. Most aircraft have fuel tank selector valves associated with the shutoff valve. Low wing aircraft normally select single tank operation while high wing aircraft select both tanks.

Every aircraft engine is designed for a specific grade of fuel. Only this grade or a higher grade should ever be used. All grades of fuel have different colors. The mixing of grades may give a colorless mixture. The smell of the also colorless jet fuel is an important safety check. Since the fumes of gasoline are very explosive the aircraft should be grounded during fueling to prevent and static electrical discharges. It is very possible to get widely varying amounts of fuel into an aircraft tank depending on the how level the ground. A level engine can make a difference of 1/2-quart reading in the oil level.

Fuels were once available as 80/87, (red) 91/96 (blue) and 115/145 (green) octane. The first two of these have been replaced by 100LL (blue)(low lead). With some changes in maintenance low compression engines can use 100LL with no problem. Because of exhaust valve damage and valve guide wear of 100/130 (green) can only be used with lead scavenging additives. Where carburetor icing is a problem, certain anti-icing additives are available to be used only after consulting aircraft manufacturer as to compatibility with fuel tanks.

Automotive fuels must have STC (supplemental type certificate) for the specific aircraft and engine before use. Such fuels may cause preignition, detonation, vapor lock and valve problems. Specific brands of fuel differ in their properties and composition. Aircraft filler openings must be marked as to minimum grade to be used.

The hydraulic system of most small aircraft applies mostly to the brake system. Since brake application puts very high pressures on the lines and hoses it is vital that the preflight check for any hydraulic fluid leaks. These leaks are best noted by the accumulation of oily dirt.

The engine also may have accessories. A battery-powered starter can turn the propeller. An engine driven generator or alternator will give enough electricity for lighting, radios and auxiliary motors. At low power a generator may be inadequate but it will function without a battery. An alternator needs battery voltage through its field coil. Then it will function even at very low engine power.

Each electrical circuit in the airplane will have a fuse or circuit breaker for protection. If something fails to work properly first confirm the switch position and then the fuse or breaker. The ampere meter will show the proper functioning of the electrical system and sometimes the load imposed. Many aircraft have an external battery plug, which will allow an external battery to be used to start the engine. The alternator will still require at least a partially charged battery.

Adjustable air vents can be set to admit outside air into the cockpit. The engine exhaust system has a heater muff, which can conduct hot air into the cockpit. If there is a leak in the exhaust system carbon monoxide can enter as well. Always mix heater air with fresh air as well has having a detector disk.

There is no reason for the small aircraft to be exposed to structural ice. Do not fly in or into weather conditions conducive to icing. The only ice prevention device on a small aircraft might be the pitot heat on the airspeed system. This should be turned on when in precipitation as a preventative measure.

The vacuum system usually runs off an engine driven pump. The cockpit has a vacuum pressure gauge that should read between 4.5 and 5.4 for normal operation. This pressure is used to operate to attitude and heading indicators. Other things may work from this as well. At vacuum pump failure the heading indicator will begin to spin and the attitude indicator will begin to tilt and remain tilted. If in IFR conditions, cover up any failed instrument.

The aircraft radio is VHF FM, which reduces interference but operates essentially on line of sight from 118.0 to 135.975 kHz. The current 720 possible frequency selections can be as selective as 25/1000ths of a kHz, such as 122.725, and 122.975 which are the 1992 additions to UNICOM frequencies. 122.72 and 122.97 may be assumed to have the additional 5 to the thousandth place. Many aircraft have an avionics master switch to reduce the frequency of radio on/off switch failure. It is best to make an initial setting of the radio volume and leave it. Use the panel switch to turn off the speaker or phones.

The navigation side of the radio goes from 108.0 to 117.9 MH FM. There is an additional switch, which allows a .05 sideband to increase the reception of navigational aids operational verification/identification code. No NAVAID should be used without such identification. The use of the NAV side to receive voice from an FSS is now obsolescent.

Comment

 
 External Links
 Recent articles
The Student As A Student
P How much does it cost Depends on motivation of student BR How long does it take 62 hours is average My students may...

Restricted Areas
P You should determine if area is quot;hot quot; or in use Hazardous area usually due to military firing bombs explosive missile activity...

Training Attitudes
A casual approach to flying can be hazardous Flying requires considerable planning and rethinking of the options as the flight progresses The midset...

Accidents By Experience Level
Less experienced pilots are more susceptible to accidents BR li Flying less than 10 hours in 30 days or less than 25 hours...

Traffic Patterns
Local rules BR Altitudes U U 100 and speeds U U 10 knots BR The idea of...

Written Tests
Private Pilot Written Test figures: P P 1997: Total tests taken 32 981 92 1 passed the test average ...

IFR Flying Faults
P Initially VFR to IFR flight results in over controlling especially when making corrections Non instrument rated pilots who fly into instrument weather lose control in...

Fatigue and Flying
P Acute fatigue occurs when a long period passes with a lack of sleep Chronic fatigue occurs when several acute fatigue periods occur without adequate recovery time...

About Students
ol li A student won #39;t learn from those they distrust BR li A student won #39;t improve unless told what...

Buying the Farm
In the `20s #39; barnstormers would travel the countryside to small cities and set up an quot;airplane ride quot; concession from some farmer #39;s field The pilot...

Statistics As of October 2001
ul li If you are rushed for time you are eleven times more likely to make a mistake than if you have ample...

CFI Hours
I took my intro flight a few days ago and when I asked my prospective CFI how many hours he had he said over 600 hrs...

Emergency Procedures
Use of checklist BR Emergency descent BR Situations where required BR Advantage of using flaps BR Speeds within 5 knots BR ...

Runup
P Use a run up checklist Always face the wind Engine cooling is the reason We are not teaching a flying career made only...

Spins Were A One Time Thing In 1914
An unheralded aviation pioneer is British scientist F A Lindemann quot;The Prof quot; as he was known led a very ...

The Risks of Flying
Most flying decisions are easy if the decision is based upon safety Being safe does not mean without risk Engine operations are safe but some 8 percent...

How We Got Pattern A and Pattern B
These patterns have been for many years a part of the Instrument Flying Handbook as among the first lessons in acquiring the aircraft control required for instrument flying ...

Pre-start/Start Checklist
P Once in the aircraft we begin the pre start tape recording Seats doors window open belts FAR 91 107 requires the pilot ...

Reaction and Anticipation
P In searching for an appropriate place for this material I was surprised at how often the terms appeared the variety of context and application to...

A Training Program
P I make a practice of having prospective students come to my home office for a couple of hours to discuss flying I request that...

Aborted Takeoff
P once is enough BR It is all too common to have a seat slide back during initial takeoff acceleration For this reason the...

Permanent Records
P Total time on airframe engine propeller since last overhaul of items required to be overhauled P P Status...

Dealing with Delays
One of the advantages of learning to fly in the fall is the greater probability of weather delays A pilot learns to live with and accept delays of any kind...

Flight Contradictions
ul li The rudder is not used to turn the plane Rather it keeps the nose straight BR...

CFI Abuses of Student Time
This problem is usually one of teaching style and respect BR 1 Coming to lesson unprepared BR 2 Failure to prep...

1999 Nall Report
li B Landings are the source of most accidents but few injuries BR li For every mile traveled airplanes...

Power-off Stalls
No lower that 1500 #39; BR Stabilized approach landing configuration full flaps BR Stall induced in back side of the power curve and heading ...

Why Takeoff Pitch Changes
P The initial lift off attitude at Vso is slightly higher than that required for Vy best rate of climb but is about right for Vx...

Ground Procedures - Taxiing Renewal
P By the time we solo we should be using power and brakes with great restraint Minimum power required to move at a good pace and smooth...

Sources of Inadvertent Stalls Becoming Spins
B 1 Inadequate rudder application in steep climbs Climb power raises nose decreases airspeed and increases P factor BR 2 False...

Taxiing
P The nose wheel linkaqe tire pressure spring tension and seat position affect taxiing and often cause turns in one direction to be easier than...

Good Judgement
font size 1 color 339966 b Good Judgement b font br P Even the best instruction will not suffice if the...

Basic Maneuver Tolerances
Altitude U U 200 feet BR Heading U U 10 degrees BR Speed U ...

Alert Areas
P High volume military flight areas are classified as Alert Areas Basic VFR requirements exist but no clearance is required Visual separation is a must ...

Spin Awareness (Discussion)
Flight situations where spins may occur BR Recognize a spin and apply recovery technique BR Techniques specific to aircraft BR power off and flaps up...

Certificates and Documents
I FONT SIZE quot; 1 quot; REFERENCES; FARs 43 61 and 91; AC 61 21 AC61 23; Pilot #39;s handbook and Flight Manual...

Fitting The Hood
P The hood should be fitted prior to engine start Note that the attitude indicator has both a wings level and a level index mark at its...

Night Accidents
1 Night emergency landings are 1 5 times as likely to result in a fatality BR 2 7 of flying is...

Minimum Equipment List
P I Reference FAR Part 91 I P P P Knowledge of required instruments and equipment for day night VFR...

Downwind Takeoff
P demonstration BR At controlled airports the non assertive pilot just goes where he is told to go There are occasions where for convenience...

Learning To Fly
P There is no single way to get a pilot license Getting it is faster and cheaper if training is done consistently with the same aircraft and...

Crosswind Takeoff
P The crosswind takeoff requires some timing skills that are not present in other landings On full power application the yoke is held full over into the...

Vertigo
P Beware of false sensations Your inner ear will give you feelings that are overpowering With low time under the hood you must avoid attempting to...

Private Pilot Sharing of Expenses
Only direct operating costs of rental and fuel ...

Carbon Monoxide
P Is poisoning due to the exhaust fumes resulting from carbon burning with insufficient oxygen to produce complete oxidation The resulting gas has one atom of carbon...

Parking and Tiedown
Use of checklist ...

Uncontrolled Airport Radio
P Start listening well away from the airport Overfly above pattern altitude if you are uncertain of pattern or procedures Adhere to AIM recommended procedures ...

Names And What
Bell decibel BR Morse code BR Doppler frequency change BR Mach speed of sound BR ...

VOR tracking
Tunes and idents station BR Holds altitude within 200 BR Locates position using radials BR Intercepts and tracks a radial BR Recognizes signal...

Diversion to Alternate
Accurate immediate turn to estimated heading finds ground speed ETA fuel conditions flies U U 200 feet U ...

 Related Links
 
©2010 4VFR.COM, All Rights Reserved Powered by 4vfr.com