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Jeppesen A&P General: Oral exam (CCC)
(A&P oral questions for General) With
Complete Solutions
Describe the result of adding a large positive number and a smaller negative number - result is smaller positive number, same as ignoring the signs and subtracting smaller number How do you convert a fraction into a decimal? - Divide the top number by bottom number What is the key step in order to add or subtract unlike fractions - finding the lowest common denominator How do you divide one fraction by another - Invert divisor (flip over the second fraction) and multiply both numerators and denominators (top and bottom numbers) How can you convert a decimal into a percent - Multiply decimal by 100 and add % sign, or move decimal TWO places to the RIGHT and add % How do you convert a fraction to a percent - Convert to decimal, move decimal two places to the right, add % How do you change a decimal to nearest equivalent fraction - Multiply decimal by desired denominator, result becomes numerator of fraction (try to get closest to whole number) Two different ways a ratio can be expressed? - 1- as a fraction
2- placing a colon between the numbers (5:54) 3- using the word "to" between the numbers What is a proportion? - a statement of equality (=) between two or more ratios: 1/2 = 4/8, 45/90 = x/ What is meant by the root of a number? - A root is two or more equal smaller numbers that when multiplied equal the specified number: the second (square) root of 9 is 3, the fifth root of 32 is 2 How do you find the square of a number? Give an example. - multiply the number times itself- 4 X 4=16, 10 X 10= 100 What is a common method of making computations involving very large or very small numbers more manageable? - Convert the numbers into scientific notation by using powers of 10. (7,234,000= 7.234 X 10^6) How is 100,000 expressed as a power of 10? - 10 to the fifth what formula is used to find the area of a rectangle? - A=L(length) X W(width) Area of a triangle? - 1/2 X B (base) X H (height) Define Pi - A constant that expresses the relationship between circumference and diameter of a circle, approximately 3. (number of times the diameter goes into the circumference)
What term defines the temperature at which all molecular activity stops? - Absolute zero Can liquids be compressed? - No, liquids are generally considered incompressible What are the units used to express hydraulic or pneumatic pressure - Pounds per square inch (PSI) Describe how pressure is transmitted when a force is applied to a confined liquid - Pressure is transmitted equally in all directions What formula expresses the relationship between force, pressure, and area - Force = Area X Pressure (F over A I P) What is the approximate speed of sound at sea level on a standard day? - 661 knots or 340 meters per second What is the atmospheric pressure at sea level on a standard day?
- 29.92 inches mercury or 1013.2 millibars On a standard day at sea level, what is temperature? - 59 degrees Fahrenheit, 15 Celsius What is the term used to describe the ratio between the amount of moisture actually present in the atmosphere compared to the amount the air could hold? - Relative Humidity
What are the four principle forces acting on an airplane in flight? - Lift, Gravity, Thrust, Drag What is the term that describes the angle between the relative wind and the chord line of an airfoil? - Angle of Attack What are the factors that cause a wing to stall? - when the angle of attack exceeds a critical value and the airflow separates from the upper surface and becomes turbulent What are the principle effects that result from lowering the flaps while in flight? - Lift increases, drag increases, and stall speed decreases What is the function of a wing mounted vortex generator? - They delay or prevent airflow from separating from the upper surface of a wing during high speed flight (prevent boundary layer separation) How does blade flapping help to compensate for dis-symmetry of lift in helicopter main rotor systems? - Flapping increases the angle of attack and lift on the retreating blade and decreases AOA and lift on advancing blade How does the airflow through the main rotor of a helicopter change during the transition from normal flight to auto-rotation?
- During normal flight air moves downward, in auto-rotation air moves upward What is friction? - opposition to relative motion between two objects in contact with each other
You must apply a correction to the specific gravity reading of the electrolyte of a lead acid battery when the temperature is outside of what two values? - when temp is less than 70 or more than 90 Fahrenheit What is the reason for having separate facilities for storing and servicing nickel-cadmium and lead-acid batteries? - The electrolytes are chemically opposite and the fumes from one can contaminate the electrolyte of the other The state of charge of a nickel-cadmium battery cannot be determined by measuring the specific gravity of the electrolyte for what reason? - There is no significant change in the specific gravity of the electrolyte as the battery is charged or discharged in Ni-Cad batteries What is the principal advantage of AC over DC? - Power can be transmitted over long distances more efficiently and with smaller wires because the voltage can be easily increased or decreased by a transformer What are the three causes of opposition to current flow in an AC circuit? - Resistance, Inductive reactance, and Capacitive reactance Define Inductance - An induced voltage which is opposite the direction of the applied voltage What component creates capacitance in AC circuits? - a Capacitor
How does a capacitor store electricity? - Energy is stored in the form of an electrostatic charge or field that exists between two conductors separated by an insulator What property of an AC circuit is defined by the term impedance? - Total opposition to current flow What are two reasons that might cause a nickel-cadmium battery to fail to deliver its rated capacity? - Faulty cells or cell imbalance What electrical values are measured by a typical multimeter? - Voltage, Current, Resistance How many views are required to represent the important details of most aircraft? - One, Two, or Three are usually enough What kinds of parts can be represented by one-view drawings? - Parts with uniform thickness like shims, plates, or gaskets What is the name for a part of a drawing used to bring out important details and how it is drawn? - A detailed view, usually drawn to a larger scale than the main drawing What is the purpose of schematic diagrams? - They are primarily used for troubleshooting systems Describe an orthographic projection - A way of drawing an object using different views at right angles to each other, such as top, front, and side view
What kinds of information about an aircraft drawing can be found in the title block? - Part or assembly name, drawing size, scale, date, company name, name or initials of people creating or approving drawing What info is contained in a bill of materials? - A list of materials and parts needed to fabricate or assemble the component or system shown in the drawing If an aircraft is loaded so that the aft C.G. limit is exceeded, what undesirable flight characteristic is likely to result? - The aircraft will be tail-heavy and may be unable to recover from a stall or spin If all the records for an aircraft are missing, how would you determine the empty weight and empty weight C.G.? - Aircraft would have to be re-weighed and new weight and balance records would have to be prepared Define "tare weight" and describe how it is handled when weighing an aircraft - Tare weight is the weight of anything on the scales that is not part of the aircraft. It must be subtracted from the scale weight reading to determine the net weight of the airplane If a piece of equipment such as a radio is added to an aircraft, how can you determine the effect on weight and balance without re-weighing the aircraft? - A new weight and C.G. location can be determined by computation. (WAM)
Why is control of the weight and balance of an aircraft important? - maximum safety What is the datum of an aircraft and what is its function? - Datum is an imaginary vertical plane at right angles to the longitudinal axis of the airplane. It is the reference point from which all horizontal measurements are taken How do you determine the moment of an item of equipment? - Multiply the weight of the item by its arm, which is the distance between the item and the datum What are two ways of determining the moment of an item of equipment? - Measure the distance between the item and the datum or use data supplied by the manufacturer What should be done to obtain a positive (plus) moment aft of the datum? - Add weight What should be done to obtain a negative (minus) moment aft of the datum? - Remove weight How does the category of an aircraft affect its loaded weight? - Aircraft certificated in more than one category such as normal and aerobatic, may have two different maximum gross weights and different useful loads What should be done with equipment that is not permanently installed and recorded on the equipment list when weighing an aircraft? - remove from aircraft
Installation of several new radios in the nose of an aircraft causes the forward CG limit to be exceeded. How can you correct this problem without removing the new equipment? - Ballast may be installed in the tail to move the CG aft How does the CG of a helicopter compare to that of a fixed wing airplane? - Helicopters typically have a much smaller CG range How do you work harden a piece of metal? - By cold working the metal Describe the primary difference between a thermosetting and thermoplastic resin - A thermosetting resin doesn't soften when heated and chars or burns rather than melting. Thermoplastic resins become soft and pliable when heated, and harden when cooled Explain how thermoplastic and thermosetting resins are commonly used in modern aircraft - Plexiglas is a thermoplastic resin used for windshields and windows. Thermosetting resins are most often used as the matrix material in composite structures Name one of the types of resin commonly used as matrix material for aircraft composite laminates - Polyester resin or Epoxy resin What are some of the materials that are commonly used as the reinforcing component in a composite structure? - Fiberglass, Aramid (Kevlar), Graphite (carbon) fiber, linen, and paper
What are the reasons that alloy steel that is responsive to heat treatment is usually less suitable for welding? - It may become brittle and lose its ductility in the area of the weld Give one advantage of pre-preg materials, other than saving time in the construction or repair of composite components - 1) Pre- preg fabrics contain the correct amount of matrix. 2) The matrix material evenly and completely permeates the reinforcing fibers.
- The matrix has the resin and hardener in the correct proportions What is indicated by the markings on the heads of solid shank rivets? - The material they are made of, and indirectly, their strength How can you keep heat treated aluminum alloy rivets soft enough to install after the quenching process? - If the rivets are stored in a freezer they will remain soft for several days What is the grip length of a bolt? - The length of the unthreaded portion How are AN standard steel bolts identified? - By the code markings on the bolt head What is the difference between a close tolerance bolt and a general purpose bolt? - Close tolerance bolts are machined to more accurate dimensions
What is the function of the sleeve on a flared-tube fitting? - The nut fits over the sleeve and draws the sleeve and the tubing flare tightly against the male fitting to form the seal Describe the two types of flares commonly used on aircraft tubing - Single and double flare How can you determine if a fitting is an AN type rather than AC type - AN fittings have a shoulder between the flare cone and the end of the threads, AC don't. What are the most significant differences between AN and AC fittings? - Sleeve length, thread pitch, and the shoulder between the threads and flare cone on AN fittings What are the names of the parts of a flare-less tube fitting - The nut and the ferrule or sleeve How do you tell a flare-less fitting from a flare type fitting? - Flare-less fittings don't have a flare cone and there is no space between the threads and the end of the fitting What is the effect of over tightening a flare type fitting - The sealing surface may be damaged or the flare cut off In addition to being securely clamped, what is an additional requirement for installing metal, fuel, oil, and hydraulic lines? - The lines must be electrically bonded to the structure What are some of the important advantages of Teflon tubing? - Compatible with nearly every liquid, has a broad operating
temperature range, low resistance to fluid flow, and has a very long shelf and service life Describe the identification markings commonly found on flexible hoses - A lay line, identification such as a Mil Spec number, the manufacturer's name or symbol, the hose size and a date code How can you determine if a flexible hose has been correctly or incorrectly installed? - The lay line will be straight if the hose is properly installed, a twisted lay line indicates an incorrect installation How are flexible hose sizes designated? - By the inside diameter, measured in 1/16 inch increments What precautions must be observed when deburring the end of a tube after it is cut - The wall thickness must not be reduced in size or fractured Describe the operation of quick disconnect couplings - Each half has a valve that is held open when coupled and is spring-loaded closed when disconnected If you fabricate a replacement for a flexible hose, what percentage of the total length must be added to allow for movement under pressure? - 5 to 8 percent What happens to the tube when a flare-less fitting is overtightened? - The tube is weakened when the nut drives the cutting edge of the sleeve too deeply into the tube
What are evidence of a cold weld? - Rough, irregular edges that are not feathered into the base metal and has variations in penetration amounts The penetration of a fillet weld should be what percentage of the thickness of the base metal - 25 to 50 percent Describe the basic steps for conducting a magnetic particle inspections - Magnetize the part, then coat the surface with ferromagnetic particles. If a defect or discontinuity is present, the particles align with the discontinuity forming a visible pattern Is there any requirement for cleaning an aircraft prior to an annual or 100 hour inspection? - It is a legal requirement as specified in FAR Part 43, Appendix D Discuss the general precautions that should be observed when washing an airplane. - Avoid or protect areas which may be damaged or contaminated such as Pitot and static ports, hinges, sealed areas, and bearings What are some of the more common light duty cleaning agents?
- Soap or detergents and water What materials are commonly used as heavy duty cleaners? - Solvents and emulsions What are the preferred cleaners for plastic surfaces such as windshields - Mild soap and water or a manufacturer approved cleaner
What type of cleaning agents should be used to remove grease, oil or fuel from aircraft tires? - Soap and Water Give at least three examples of the factors that cause or influence corrosion - 1) The environmental conditions 2) The presence of dissimilar metals 3) The type of metal 4) the presence of electrolytes and or contaminants 5) The condition of protective coatings Name at least three forms of corrosion - 1) Surface 2) Intergranular 3) Filliform 4) Dissimilar metal (galvanic) 5) Oxidation 6) Pitting
- Stress 8) Fretting Name at least one cause of filliform corrosion - 1) Improper or incomplete curing of a wash primer prior to painting 2) Failure to completely wash off acidic surface contamination What are the visible signs of filliform corrosion? - Blistered paint surfaces, worm or thread-like tracks under the paint What are two primary factors that may cause development of stress corrosion cracks? - A corrosive environment and sustained tensile stress What are the visible signs of fretting corrosion? - Corrosion residue has a dark, smoky appearance and often appears around and streaming back from rivet heads
