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Health Factors
Age as a Factor in Flying; Fatigue; Sleep; Medicine; Carbon Monoxide; Cold Weather; Dehydration; Ear Problem; Hyperventilation; Hypoxia; Smoking; Coffee; Spatial Disorientation; Stress; Vertigo; Nutrition:
H. Task: AEROMEDICAL FACTORS
Pilot Operation - 1
References: AC 61-21, AC 67-2; AIM
Ex Explain cause, symptoms, effects, and correction for...
The average General Aviation pilot was 39 years of age in 1990. Pilots over 60 have 2.1 times more accidents than pilots in their 50's. Pilots over 60 are safer than pilots in their 20's and 30's. The accident rate goes up after 60 perhaps due to subtle age-related deterioration in cognitive function. The older you are the dumber you get! My wife agrees.
Older pilots like to think that what has been lost in ability has been made up in experience. By the age of 60 pilots lose some mental and physical abilities. By the age of 50 everyone has some vision loss known as presbyopia. Hardening of the lens causes this. As we age we become less efficient in getting and using oxygen and getting rid of carbon dioxide. Hearing by itself does not affect the ability to fly but it does make a difference in the communications area. Like vision, hearing the higher frequencies drops with age. Physically we become victims of some stiffness of the joints and extremities with age. Dehydration is going to have greater effect with age. We are all different in the way we age and the way our aging affects our flying.
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 between. While some fatigue is related to lack of sleep, not all is. Fatigue can result from inadequate nutrition and over exertion. More information needs to be obtained on fatigue distinguished from sleep as a factor in accidents.
Some factors of physical condition are controllable and some are not. 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 between. Stress is the result of events causing preoccupation, reducing external awareness, and making activities subject to distraction. Stress causes the taking of risks that would otherwise be unacceptable. The mental/physical condition resulting from fatigue and stress may cause the pilot to make unwise decisions.
There are many causes of fatigue: lack of sleep, hypoxia, noise, time zone factors, temperature extremes, dehydration, stress and more. When you are fatigued you are more irritable and easily annoyed, you will suffer for lapses in short term memory, your attention will fixate to the exclusion of all else, your performance skills will decrease and you will be unaware of any impairment.
The causes of fatigue are primarily lack of recent sleep or a chronic sleep deficiency. Additional fatigue arises from our physiological reaction to noise and vibration, illness, hunger, caffeine "down time", unresolved stress, hypoxia, dehydration, errors in judgment and extended mental/physical demands.
What to Expect from Fatigue
Reduced vigilance
Increased temper excursions
Reduced ability to concentrate
Reduce awareness of deviations
Increased rationalization of errors
Increase in ‘know-better’ mistakes
Fatigue increases if you are "doing nothing"
Reduced comprehension of ATC instructions
Subtle Fatigue
This problem often begins with a distraction that causes fixation on an instrument or occurrence. Complex flight operations are the first skills to deteriorate.
Silence prevails
Seat posture relaxes
Bad judgment prevails
Instruments are ignored
Attention and vision fixates
Eye/hand skills begin to fail
Writing becomes less linear
Heading excursions take place
Movements decrease and slow
Clearances cannot be copied in total
Knowing where you are becomes a problem
Pilot accepts what exists as O.K. without checking
External references begin to fade from consciousness
Sleep
The most common cause of diminished alertness and proficiency is lack of sleep. This condition is said to affect 30% of the U.S. population. This may be due to an actual loss of sleep or a change in a sleep pattern called the circadian rhythm. Pilots tend to neglect their need for sleep. The need for sleep is a defining limit to pilot mental capability. You must have sleep or your mind will fail. Once beyond the limit pilot performance deteriorates and can become irrational. Sleep is a restorative and can be both stored and deprived within limits set by the biological clock of the individual. As you grow older you will need less sleep. Jet lag sleep patterns are worse when flying from west to east. Accident rates climb precipitously when your body begins demanding sleep. The average American gets about one hour too little sleep each night.
Accident rates rise in the afternoon and become significant at night. Postponing sleep causes a sleep deficit that as it increases an accident becomes more likely. Jet lag is a type of sleep deficit. A sleep deficit can best be resolved by going to bed early, not by sleeping late. A large deficit cannot be made up in one night. 21% of aircraft accidents cite sleep deficiency as a factor.
When drowsiness occurs you cease to monitor the instruments. You will tend to fixate and drift off mentally. We go into a mental autopilot not thinking of what we are doing. This is the lowest level of alertness. The next level of alertness is one in which you are in constant search-and-scan, seeing what you are looking at, hearing what is said and asking question. This is the flying" mode from pre-flight to shutdown. This gradual deterioration of alertness is best observed in watching others. It can creep up on you and influence your flying without your even noticing. Your alertness rises again when you have located a problem. You focus on it and prepare to execute a solution. This might occur when required to make a crosswind landing. The highest level of alertness is when adrenaline begins to flow and survival becomes a factor.
Any over-the-counter medication whose name ends in "ine" should be checked in a flight medical examiner for use before flying. Beware of any medicine that is supposed to make you feel better. At altitude the effects may be damaging to flight safety.
Medicine taken is just as likely, even more likely, to be the basis for grounding a pilot than is the ailment itself. Medicinal side effects are both variable and unpredictable. Virtually all medications have side effects. Never take a medication for the first time and then fly. Make the safe decision if you are sick.
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 and one atom of oxygen. CO is odorless, colorless and cannot be tasted. CO poisoning may not be distinguished from fatigue or hypoxia except that the occurrence can occur at any altitude. Engine exhaust in an aircraft has 7% CO. Very small amounts of CO over a period of time will reduce a pilot’s ability to fly safely. It is the length of exposure as well as the amount that makes the critical difference. Susceptibility to CO poisoning increases with altitude due to the propensity of CO to enter blood. CO is 200 times more attracted to the blood hemoglobin as is oxygen. As little as one part CO to 20,000 (.005%) parts of air is enough to begin the death process of the brain.
Above 10% CO poisoning you will suffer from a headache. Above 20% you will be sleepy and sick to your stomach, HEADACHE, vision and speech problems. You will be incapacitated above 40% and dead at 70%. If you get a headache while flying, open the window and shut off heater.
CO reduces ability of blood to carry oxygen. Symptoms are similar to hypoxia. Headache, drowsiness, dizziness should initially be corrected by opening outside air vents. CO has a half-life in your body of about five hours. It will take a full day to recover. 70% of exhaust system failures result in CO poisoning. CO prevents the hemoglobin from both carrying and releasing oxygen. Antihistamines, alcohol, lack of sleep, or blood deficiency will exacerbate CO poisoning. Prevention of CO poisoning is directly preventable by proper aircraft maintenance. Club aircraft require extra alertness. You might suspect CO exists in your cabin air as soon as you smell some engine exhaust fumes.
Descend
Land ASAP
Use any oxygen
Shut off the heater
Get medical treatment
When in doubt, get on the ground.
Hot or cold temperatures affect the quality of the preflight. In the winter, as your body cools you tend to mentally and physically slow down. Flying in an unheated aircraft in the winter will drastically decrease your flying efficiency and effectiveness.
Human need for 2-4 quarts of water a day. You become thirsty with a deficit of 1.5 quarts of body fluids or 2% of body weight. The deficit causes a reduction in blood volume and triggers thirst. Thirst arrives too late and can be mollified too easily. At 3% of body weight fluid loss fatigue and weakness occurs. Symptoms are headache, sleepiness, dizziness and weariness. Avoid diuretics such as coffee and alcohol. Don’t rely on thirst as drinking trigger. Measure fluid intake daily.
Caused when the Eustachian tube becomes blocked. Earblock or sinus blockages can cause differential air pressures to exist between cavities of the skull and the exterior. If it is not possible to equalize these pressures by slowing or removing the pressure changes severe pain results. Do not fly if you suspect such a condition exists or above 8,000’ within 24 hours of scuba diving. Gum chewing and jaw movement are preventives. The Valsalva maneuver consists of opening the mouth wide with the jaw wide, as though yawning. Do this over and over because opening the mouth helps open the Eustachian tubes. Next, pinch your nose closed, shutting the mouth, and blow gently as through your nose.
Stress, anxiety and fear cause hyperventilation. The person begins abnormal rapid breathing. Reduction of carbon dioxide causes lightheadedness, suffocation, drowsiness, tingling, and coolness. Leads to incapacitation, spasms, and unconsciousness. Symptoms resemble hypoxia. Can be corrected by controlled breathing in a paper bag.
An adult will breath in 3,000 gallons (by volume) of air per day. This includes 600 (20% of total) gallons of oxygen. Your blood system has 25+ trillion (12 zeros) red blood cells (hemoglobin). Each one is capable of loading up four oxygen molecules for distribution throughout the body. when returning to the lungs for a refill they unload CO2 first.
Hypoxia is oxygen starvation. Lack of oxygen impairs the whole body but most importantly the brain. The first part of the body to show significant effect from oxygen deficiency is the retina of the eye. Every individual is affected but in different ways and to different degrees. The danger in hypoxia is that it occurs insidiously below the conscious threshold. Hypoxia makes you happy and such happiness in the cockpit is very dangerous. The best warning indicator for hypoxia is the altimeter. You will quickly recover by descent to a lower altitude.
Since hypoxia is due to reduced barometric pressure, low-grade hypoxia begins on takeoff. The percentage of oxygen is same but less is reaching the blood stream. Any stress or increase in activity requires more oxygen, up to 8 times more. Pilot performance deterioration begins at takeoff, as well. Slowed response times and inability to deal with complexities due to hypoxia compromise safety. Noticeable oxygen deficiency effects begins at 4000’ safety margins are beginning to erode. Hypoxic symptoms of difficulty breathing or headache may not be obvious or may not occur at all even though there are the foregoing changes in mental status.
I have seen complete personality changes occur after a couple of hours around 12,000’. Symptoms such as headache, drowsiness, dizziness, euphoria, tingling, perspiration, or belligerence are typical. Tunnel vision and blue fingernails occurs with times as little as 15 minutes above 15,000’. At 16,000’ disorientation, lapses of judgment, loss of impulse control, risk-taking behavior, decreased problem solving abilities, impaired memory, mood disturbances, and lowered coordination are common. Unconsciousness occurs in 10 minutes at 20,000’.
All effects are made worse and happen at lower altitudes with fatigue, age, smoking, health habits, and drinking. Oxygen recommended above 10,000 day and 5,000 night. If oxygen is being used, the pilot must be knowledgeable about the operation of the system and be able to recognize his and the system’s warnings of oxygen deficiency. FARs require oxygen if ½ hour above 12,500’, crew above 14,000’, everybody above 15,000’.
The smoking of tobacco is a form of self imposed physical and psychological stress that constitutes an immediate and on-going threat to health and safety. A smoker may deny that drugs are a part of his life. He lies in the face of facts. The whole purpose of a cigarette is to get a nicotine fix. Different from cocaine or heroin? How? The person who smokes is a health and economic hazard to everyone. The residue remains on his person, clothes, possessions, and associates.
Susceptibility to CO poisoning increases with altitude due to the propensity of CO to enter blood. This prevents the blood from being able to transport adequate oxygen to the body’s cells. The hypemic hypoxia of the smoker reduces his oxygen intake by 5-10 % of normal capacity. The fact that smokers are hypoxic means that we can expect smokers to feel anxiety, forgetfulness, irritability, confusion, altered judgment with every cigarette. Judgment, math ability, and reasoning will be affected. The indication is that smokers are more likely to enter into personal arguments and show lack of both good judgment and logical reasoning ability in those arguments. Very small amounts of CO over a period of time will reduce a person’s ability to perform safely. It is the length of exposure as well as the amount that makes the critical difference. This lack of oxygen to the brain impairs judgment and diminishes the ability to make reasoned decisions.
Any onset of sluggishness, warmth, and tightness across the head is an early symptom of CO poisoning. A headache, weakness, dizziness and dimming of vision comes next. You won’t be aware when you lose strength, vomit, convulse, and enter a coma. A breath of fresh air will not revive you. Several days may be required for full recovery. The smoker is betting against a CO impairment that has already occurred and can only become worse. Carbon monoxide and other toxins in tobacco smoke interfere with the oxygen-carrying capacity of red blood cells. Less oxygen means less energy. Smoking causes an accumulation of mucus in the windpipe and bronchial tubes constricts blood vessels and reduces the supply of oxygen to cells.
The pilot who smokes is a hazard to himself and other pilots. The fact that smokers are hypoxic at relatively low altitudes means that we can expect smoking pilots to feel anxiety, forgetfulness, confusion, irritability, and altered judgment at relatively low altitudes. The applicable question is, should smoking pilots have any more right to fly than drinking pilots? Know your limitations. Don’t fly if you are not 100%.
Half of the American population is addicted to coffee. 25% drink ten or more cups a day. Quitting coffee is both difficult and painful. At age 71 I dropped coffee primarily to lower my blood pressure. I had a two-week headache. Now I take afternoon naps. The lure and temptation of coffee still exists.
Coffee has some negatives:
1. Raises the adrenaline level.
2. Linked to heartburn and ulcers.
3. Leading cause of sleep disturbance.
4. Constricts blood vessels of the eyes.
5. Contains at least five cancer causing compounds.
6. Contains pesticides that are not allowed in the U.S.
7. Contributes to iron loss, zinc loss, and sex drive loss.
8. Increases risk of stroke by increasing blood pressure.
9. Blocks adenosine, a brain chemical that calms you down.
10. Can cause panic attacks by increasing lactate in the body.
11. Can addict babies whose mothers drank during pregnancy
12. In conjunction with diet, cold, anti-depressants will dramatically
raise blood pressure.
13. Causes excretion of calcium, potassium, magnesium and sodium
before being used by the body due to diuretic effect.
Spatial disorientation is the No. 1 cause of military fatal accidents. Even the best pilot will become disoriented under the right conditions. Effects on inner ear can cause a mentally and physical compelling move in a given direction. This can be the after effect of a gradual turn, spiral, spin, acceleration, leveling off, updraft, false horizon, autokinesis, (lights that move), runway illusions.
Human performance is mitigated by physical stresses such as fatigue, fitness, sleep, food, age and illness. Psychological stressors such as personal family problems, work load, situational awareness. External dynamic stresses due to weather, turbulence, aircraft performance and time factors. Stress is the result of events that cause preoccupation reducing external awareness and making activities subject to distraction. Stress causes the taking of risks that would otherwise be unacceptable.
Stress in moderate amounts is both necessary and desirable when flying. It prevents boredom and inhibits fatigue. The other extreme of stress leads to panic and impaired capability. Accidents happen when flying requirements exceed capability. Time in the air will decrease capability and lower the stress/panic threshold. 69% of accidents occur in the landing phase of flight operations. This is when time in the air is greatest and the stress/panic threshold lowest.
Whenever excessive tension exists, the ability to make considered judgments deteriorates. The concepts of what is best or safest become an emotional decision based more on fears or concerns rather than realities. Under tension the ability to make correct decisions deteriorates and compounds both the tension and the reliability of the selected solution. The pilot MUST recognize areas of tension and undertake an instructional program to raise a proficiency level to where competence reduces tension. Failure to resolve any tension-producing problem will eventually lead to an unforeseen situation where a decision will produce an accident. The instructional program must expose the student to those tension producing situations before the student goes solo. Stress exposure is a form of stress inoculation.
The most common tension producer is through use of the radio. At a given point in airspace the student knows that he should be prepared to say a given sequence of communication facts. Where to start talking, what to say, in what sequence, and the fear of the unknown ATC create tension. After being lost or disoriented the most dramatic tension producer is x-wind landings, next I would place unfamiliar airports, especially if they are small, followed closely by radio procedure uncertainty. Night flight over unfamiliar terrain certainly raises cockpit temperature. Turbulence produces tension in the best of us as does proximity to the ground. All of these tension producers can be reduced or eliminated by gradual programmed exposure. Stress reduction, according to one expert, can be achieved by only landing at airports and peeing every chance you get.
Unrecognized spatial disorientation is caused by some combination of channeled attention, distraction and target fixation. These most often occur in conjunction with loss of situational awareness due to excessive workload. A 10-degree bank with only the approach lights visible can cause an illusion that the lights are sloping from above. The future microwave landing system flown mostly with curved approaches is going to require special illusion training.
Recognized spatial disorientation is when the pilot is aware of his disorientation and should be able to work through a recovery sequence by establishing recommended power and attitude changes. Pilots have, over the radio, acknowledged their vertigo and inability to overcome it prior to crashing.
Incapacitating spatial disorientation occurs when the motion of aircraft is so severe that pilot may be incapable of rationally perceiving and processing information and making decisions. May cause nystagmus (trembling of the eyes) which makes reading of instruments impossible. Rare but can occur in extremes of weather or flight conditions. Other types of spatial disorientation are illusions such as caused by runway/cloud sizes, shapes, or slope.
Vertigo is the #1 cause of Air Force fatal accidents. Vision is the pre-installed vertigo preventative. A moments glance out-the-window is all it takes. This will overcome any sensations from other sources. However, without vision, the organs of balance in the inner ear take over. The semicircular canals approximate the three axes. They contain a fluid that stimulates our senses of angular acceleration in these axes. The otolith organs establish our sense of uprightness. Tiny stones affect hair sensors in reaction to "gravity". Otoliths sense linear accelerations, not angular accelerations, and regardless of the direction interpret such accelerations as gravity. In our muscles and joints we have sensors which give additional information about push or pull. Unless one or all of these sensors are confirmed by vision we are on our way to vertigo.
Food when converted into glucose is the source of brain energy. Glucose cannot be stored. As blood sugar it requires constant renewal. If glucose is not renewed the body and the mind shows evidence of fatigue, mental confusion, faintness, headache, memory loss, dizziness, vision problem, cold hands and feet.
Reduced blood pressure, tension, depression and hunger are all symptoms of hypoglycemia. This can be caused by the lack of a balanced meal within the past five hours. Ten hours without food will severely affect decision-making ability, alertness, coordination, and perception. Skipping breakfast causes fasting hypoglycemia. All hypoglycemia types can be aggravated by other physiological factors.
Altitude can incapacitate a pilot through dehydration. Increase your fluid intake prior to and during flight. What you eat is just as important as just eating. Reactive hypoglycemia can cause lack of consciousness. This is a reaction to the doughnut/candy bar meal. The student pilot who does not eat because of possible airsickness is endangering himself if flying solo. High sugar meals cause the pancreas to create excess insulin. Insulin allows the body to use sugar. Too much insulin and deplete sugar to such a low level as to incapacitate the body and mind. Adding caffeine, alcohol and nicotine acerbates the problem. Flying should be preceded by a balanced meal. Neuronutriments are the vitamins and minerals that the body can change into neurotransmitters. Trace minerals such as potassium, zinc, iron, and chromium are essential to control the body’s sugar burning process. The more balanced our meals the better will be our mental functioning and memory.
Systems and Paperwork
DETERMINING PERFORMANCE AND LIMITATIONS; Performance sheet ASEL; OPERATION OF AIRPLANE SYSTEMS; MINIMUM EQUIPMENT LIST; Permanent Records; Engine Logs; Inspections; Operating without a (MEL); MEL Decision Sequence; Repairs; Airworthiness Directives (ADs); Service Difficulty Reports (SDRs); Service Bulletin; Maintenance Records; Airworthiness Directive; Pilot/Owner Maintenance; Most dangerous thing in aviation;
E. Task:DETERMINING PERFORMANCE AND LIMITATIONS
REFERENCES: AC 61-21, AC 61-23, AC 61-84, Airplane Handbook and Flight Manual
P Figure weight and balance, takeoff, climb, ceilings, range, fuel consumption, TAS, altitude performance, locate all V speeds, landing performance, and final determination of aircraft capability.
EX Effects of weight, effects of balance, ground roll and clearing 50', altitudes effect on fuel, meaning of TAS, meaning of service ceiling,
significance of all V speeds, use of flaps, airspeed indicator, RPM, and way of determining capability.
(You must be able to locate any information related to the aircraft.
You may be asked to apply selected data to any one of the charts.)
Performance sheet
ASEL
Compute weight and balance with gross takeoff weight___________
Center of gravity location ________
Gross landing weight __________ Center of gravity location _________
Shift weight from _________ to the _____________New center of
gravity locaton _________
Cross Country Flight Plan
Total distance is __________Total time is ____________Total fuel
used is __________
Total fuel remaining including reserve ___________Is a fuel stop required for this flight? ____
Plan takeoff over a 50’ obstacle at full gross weight at sea lever with an outside air termperature of 30 degrees centigrade ____________
Discuss density altitude and performance.
Plan a landing over a 50 foot obstacle at landing weight at 3000’ pattern altitude with an a standard outside air temperature.
Whis is the best endurance altitude and power setting for this aircraft? _________
What is the range of this aircraft at 75% power? ________ amd 65% power?_______
Weight affects the stall speed of an airplane. Book figures are at gross weights. An overweight plane will stall before the book figure; a light plane will stall at a slower speed. Flight in excess of gross weight is prohibited. Alaska allows 10% over for survival gear. Most aircraft are close to gross when they have full fuel. Reduction of fuel load is the best adjustment factor.
Controls are designed and certified to perform properly within
a certain balance/speed range. Va or maneuvering speed (abrupt
control movement allowable) is published for gross weight only.
An out-of-balance plane at low speeds may not have the effectiveness
required for control. This means that the elevators may not be
able to properly raise the nose of an airplane while taking off
or landing. They may not be able to effectively lower the nose
in climb, slow flight or landing. All performance figures are
predicated on a properly balanced aircraft. An aircraft that is
out-of-balance causes performance figures to change for the worse.
This is especially true regarding fuel consumption.
Takeoff data is figured for standard conditions with factors added
for wind velocity and runway conditions. Since conditions are
seldom standard, you must compute any effects of density altitude
or non-standard conditions. Climb is figured likewise. The performance
increases at roughly the percentage of the weight reduction. Fly
10 % below gross weight expect takeoff climb and range to improve
about 10%.
Fuel consumption may be determined by power applied. Altitude normally decreases the air available to the fuel mixture making possible a reduction (leaning) of the mixture. At altitude the engine has less power and consumes less fuel while at the same time getting more distance. In no wind/tail wind conditions it is more economical to fly high. Density altitude conditions affect fuel/air relationships as well. Fuel consumption, leaned, is about .44 pounds of fuel per hour per horsepower. For the C-150 this gives, .44 X 100 hp /6 lb. per gal = 7.3...gallons per hour. With 22.5 useful capacity and the tanks not really topped off (prevents waste) three hours flight time with the required 1/2 hour daytime reserve comes up short. The manual gives more optimistic figures predicated on lower horsepower available at altitude.
The true air speed (TAS) is calibrated airspeed (CAS) corrected for air density. This is the manufacturers manual speed, which you use for navigational purposes to find ground speed. For practical use it is too optimistic due to the differences between new and abused (sic) aircraft. The service ceiling is required knowledge since it makes no sense to plan a flight across terrain above aircraft capability. At service ceiling the plane can still climb 100 feet per minute. Density altitude factors can greatly affect both this ceiling and the absolute ceiling.
The V speeds are determined through exhaustive study by the manufacturer to be the best speeds for a specific desired performance. While these speeds may vary somewhat with aircraft weight they are required knowledge as a base for performance. V speeds are indicated speeds, which are to be flown within the ranges, specified in the Practical Test Standards. V speeds are usually found near the front of the aircraft annual with explanation. It is best to locate, and know for the flight test, the significance and number of all the V speeds such as: Vx, Vy, Va, Vne, Vfe, etc.
Broad performance - specifications of the aircraft are on back of the front cover or on the first few pages of the manual. For specific performance under conditions see the chapter index. Putting labeled tabs on certain charts related to takeoff, landings, emergency, and power settings would make location easier. FAR 91.103 requires that we calculate required runway lengths for takeoff and landing. You need not know everything in the manual but you must be able to locate desired information efficiently. It is not recommended to ever fly without a manual available. Va, maneuvering speed, is slower at lighter weights. So are stall speeds. The maneuvering speed is a limit on control movement. Since the aircraft loading moments between control pressures and turbulence pressures differ, the allowable turbulence speed may be a bit higher than Va.
Since the use of flaps and slips varies so widely between aircraft, it is important to know what is specifically required, permitted or prohibited for your aircraft. The stronger the cross winds the fewer degrees of flap recommended. The maximum demonstrated crosswind component is not a limitation. It is something required as a demonstration. Make sure to know under what conditions slips are allowed or not. For takeoff be sure to know the required flap setting for specific performance. Partial and full flap settings may have different airspeed limits. Application of flaps before slowing to required speeds will be harmful to the aircraft. The way flaps are removed in flight depends upon the airspeed. Below Vx they should be milked off slowly until Vy is obtained while holding altitude. At Vy or higher removing the flaps all at once should not create a problem.
It is advisable to have your own manual for every aircraft you fly.
F. Task: 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.
G. Task: MINIMUM EQUIPMENT LIST
Reference FAR Part 91
P Knowledge of required instruments and equipment for day/night VFR Procedure to flying with inoperative instruments and equipment. How to get special flight permit.
Total time on airframe, engine, propeller, since last overhaul of items required to be overhauled.
Status of life-limited parts, inspections, airworthiness directives.
Copies of all FAA Form 337s with duplicate to FAA in OKC
IFR records on pitot/static system, altimeter, transponder, encoder and VORs.
Inoperable equipment must be entered into maintenance logs.
Overhaul
Does not change prior history. Time is added as "since overhaul". Work by FAA licensee.
Rebuild
Time in service begins anew. Rebuild must be by FAA approved depot.
FAR 43.11(a)(b) Type, description, date, total time, signature, certificate type and number; approval or disapproval for return to service Advisory Directives (Ads) compliance (work, inspection, repair) completed and signed off
Routine
100 hour, minor alterations. A & P sign off required
Required
Annual or progressive, major alteration AI sign off required and compliance with ADs.
Manufacturer's
Not in FARs but require A & P signoff
Minimum Equipment List
Most older aircraft have been certified without a MEL but everything operational when the aircraft was certified must be operational for flight--including the cigarette lighter and tire pressure.
Without an MEL any inoperative item must be removed or deactivated and then placarded. A certificated mechanic must do the work, adjust the weight and balance, complete FAA Form 337 and approve for return to service.
The pilot recognizes inoperative instruments or equipment
Question:
Is the item required by MEL or kinds of operations list?
If "yes" aircraft is unairworthy!
If "no" 91.205, 91.213(d)(2)(ii)
Is the inoperative item required for this flight?
If "yes" aircraft is unairworthy!
In "no" 91.213(d)(2)(ii)
Is the item required by airworthiness directive (AD)?
If "yes" the aircraft is unairworthy
If "no" 39, 91.213(d)(2)(iv)
Is the item required by FAR 91.107, 91.171, 91.185, 91.205, 91.207, 91.209 etc 91.213(d)(2)(ii)
If "yes" the aircraft is unairworthy
If "no"
The item must be removed or deactivated and placarded inoperative
91.213(a)(3)(i), 91.213(a)(3)(ii)
Pilot must determine that the item does not constitute a hazard under the conditions of the flight. Pilot may perform work that comes under preventive maintenance. Item: Under the strictest interpretation of the FARs, it is almost impossible to fly a legal, airworthy aircraft.
FAR 91.213 is distinct from FAR 91.205 which just lists what is required for specific operations. 91.213 says you can’t fly with inoperative instruments or equipment. Without an MEL, the alternative is in subsection (d), which requires a placard, plus deactivation or removal. Subsection (d) places total responsibility on the pilot.
1. The pilot must determine hazard potential, if any.
2. Determination may be made by certified mechanics.
3. Owner/operator must confirm if required for selected flight
operation.
4. Refer to POH for selected flight operation.
5. If not required, deactivate and placard or remove by certified
maintenance person who must make required placard and logbook
entries.
6. Inoperative placard must be replaced at each required inspection.
The main difference between a 100-hour inspection and annual inspection is that the airframe and power plant mechanic can sign off the 100 hour but the annual sign-off requires inspection authorization. While an in-flight operational check may not be required it is very worthwhile. The pilot making the flight should sign the logbooks.
Minor FAR 43.9(a) compliance
Work done, date completed, certificate type/number, signature.
TT (total time) not required
FAR 43.9 requires that the person performing preventive maintenance must record the work in the maintenance records. The record must contain a description of the work, the date of the work, the name of the person doing the work, and approval or disapproval the aircraft for return to service.
Major
Return to service by FAR 65.95
Repair stations
FAR 145 for propellers, instruments and avionics
Discrepancies
Need not be listed in logbook but separate discrepancy list must be signed off
Airworthiness Directives (ADs)
FAR 91.403(a) requires that an AD compliance record be kept. Some AD are one-time and others recurring. They notify aircraft owners and others of unsafe conditions and what must be done to operate the aircraft. ADs may be an emergency, which requires immediate compliance or less urgent nature with some time slack allowed. ADs are FAR’s and must be complied with unless exempted. There is no ‘overfly allowance as may exist with inspections. FAR 91.417 requires a record be maintained showing status of all ADs applicable to an aircraft. This often is on a separate sheet.
Service Difficulty Reports (SDRs)
SDRs are a mechanics’ report on maintenance problems. These are collected by the FAA and aircraft manufacturer and passed on to maintenance facilities as ADs (Airworthiness Directive) or as a maintenance suggestion. SDRs make up about 10% of all reported problems.
The most common items reported are those under the greatest stress. Exhaust valves, crankshaft weights, and valve train problems are most common. Cylinder reports relate to cracks at exhaust port area. Magneto problems relate to failed coils. Certain engine models are subject to specific reports related to inherent weakness such as case cracking in Continentals. Lycoming has engines with valve wobble problems. If ever you own an airplane, get an SDR listing for it.
Issued by manufacturer about service problems and solutions. The solution is not mandatory as with an AD.
The owner/operator is responsible for all required maintenance, inspections and logbook entries on an aircraft. FAR 43 gives entry examples of ‘appropriate" entries. This includes compliance with the FARs such as FAR 91.403(a) and FAR 91.405. 91.405 requires maintenance sufficient to keep aircraft airworthy. The owner-operator must retain the log books, be responsible that proper entries are made, and be able to make them available to authorities.
All records of maintenance and inspections require that entries say what has been done, the date of completion, signature and certification of the one doing the work and sign-off. A proper sign-off applies only to the work done. An inspection does not make the aircraft airworthy. An aircraft is airworthy only when work specified in the inspection as being required is completed and signed-off.
FAR 91.213(d)(2) covers inoperative equipment. This requires that any inoperative instrument or equipment have a signed placard FAR 43.11 as well as logbook entries regarding the action taking. Approval for return to service is required. Maintenance is the owner/operator responsibility; airworthiness is the pilot's.
FAR 91.7(b) "The pilot in command of a civil aircraft is responsible for determining whether the aircraft is in a condition for safe flight." If anything untoward happens the FAA gets to second-guess the pilot's decision. The regulations on maintenance and inspections are in FAR 91.403(a) and 91.405. 91.3 states: "The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft. Again, if anything untoward happens the FAA gets to second-guess the pilot's decision. The PIC determines airworthiness in the preflight, review of paperwork and checking aircraft maintenance records. The aircraft must meet and continue to meet it original type design data unless approved changes are made.
(AD)Compliance Record
Aircraft No: Make: Serial Number
Aircraft Model:_______________________________________________________________
AD # Date Subject Compliance Method of Date of Airframe Component One-time Recurring Next Authorized and Received Due Compliance Compliance Total Time Total time in Compliance Signature
Amend Date/Hours Service at Service at Date/Hours Certificate
Number Other Other Type & #
Aircraft Record keeping Requirements of Part 91
Regulation Required Required Recordation Retention
Records Entry Location Requirement
91.411 Altimeter and Encoder Date and maximum altitude Maintenance Log 24 months
Signature, # Permanent
91.413 Transponder tests Test, date, signature # Maintenance log 24 months
Permanent
91.417(a)(i ) Preventive, alternations Work performed, date completed Maintenance log Until repeated,
91.417(b)(i) 100 hr, annuals, required, Signature, certificate # of person Component log suspended, or approved inspections returning aircraft to service for one year
91.417(a)(i) Total time in service Identification /serial number Maintenance log Indefinite
91.417(b)(i) airframe, engines, Total time since new/overhauled Component log
propeller .
91.417(a)(2)(ii) Status of life-limited parts Identification /serial number Maintenance log Indefinite
91.417(b)(2) airframe, engine, propeller, Total time since new/overhauled Permanent record
or appliance
iii Time since last overhaul Identification/serial number Maintenance log Indefinite
as required on time basis Total time of service since Permanent record
________________ last overhaul .
iv Inspection status, time Type/time of last inspection Maintenance log Indefinite
since last defects found, items deferred Permanent record
v Status of ADs, time/ date DA number, revision date, Maintenance log Indefinite
when next required date of compliance, method AD Compliance record
and time/date of next action Permanent record
Signature/ Certificate # .
vi Form copies prescribed by Specified on Form 337 Form 337 attached Indefinite
FAR 43.9(a) for major alternation
Keeping an aircraft clean greatly improves both its appearance and its performance. When you clean an aircraft you learn a great deal about its construction and maintenance. You become aware of small defects and maintenance problems. Cleaning protects the thin layer of paint from the corrosion potential of dirt and airborne chemicals. Detergent and water are the best aircraft cleaners. If heavy grease must be removed be sure to obtain something other than a household cleaner should be used. Specifically, get a degreaser designed only for aircraft use.
Only aircraft type cleaners should be used on plastics and Plexiglas. Using a dry cloth on Plexiglas will cause an electrostatic charge to develop what will attract dust. Washing is the best cleaning method for Plexiglas.
Oils and solvents from the ground or in the air damage natural rubber more than synthetic. Light, especially sunlight will affect the durability and elasticity of rubber. Keep your tires both clean and out of direct sunlight. Keep all rubber surfaces free of hydrocarbons.
Frequent use of a specific aircraft gives the pilot an opportunity to determine what normal operation feels and sounds like. Knowing this makes early detection of abnormal conditions more easily detected.
WD-40 and Cleaning
The use of WD-40 is not recommended on aircraft. It is not recommended because only a light lubricant is left after the solvents evaporate. Use Kroil or ACF-50 available through aircraft parts houses. The use of steam cleaning and pressure washers on aircraft is not good practice since lubrication points are not sealed. Open bushes, pivot points must be dismantled to grease. Pressure washes flush out the oil and will wet the interior making it subject to corrosion.
Most dangerous thing in aviation:
"A pilot with a tool box." or "A politician with a good idea."
FAR 43.7(f) says that a Part 61 pilot may do preventative maintenance on an aircraft used in Part 91 operations provided it does not involve complex assembly operations. The pilot can approve for return to service after work under FAR 43.3(g) 29 items are listed. The complete index is in FAR Part 43, Appendix A.
The pilot can:
Replace safety belts
Remove, install and repair tires
Replenish hydraulic fluid in reservoir
Replace, clean and space spark plugs
Replace and service batteries (Not ELT)
Replace bulbs, reflectors and lenses in lights
Trouble shoot and repair landing light circuits
Replace defective safety wiring and cotter keys
Servicing landing gear shocks by adding oil or air
FAR 91.7 makes the pilot responsible for the airworthiness of an aircraft. Assumption of this responsibility carries with it responsibility to become and remain knowledgeable about the aircraft and its systems. The owner/operator is responsible for the actual financing of the maintenance. A certified mechanic must inspect any work done and make required entries in the records of the aircraft. FAR 43.3(d) requires that the mechanic personally observe the work and be available while the job is in progress. However, the FAA gets to second-guess all actions by these parties if something occurs.
The best care you can show toward your engine is to use it along with some good pilot procedures. A sitting engine will rust and corrode. Avoid descents with reduced power which may cause shock cooling; high rpm starts which fail to provide required initial lubrication; and, excessive leaning at high rpm which will burn exhaust valves.