AIRFRAME ACS CODES EXAM QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026

AIRFRAME ACS CODES EXAM QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026 Non-Metallic And Sheet metal - Answers How do you determine the total lenght of a solid rivet for installation? - Answers The grip length +1.5 x the rivet diameter. What is done with the rivet head stem when a self plugging rivet is installed? - Answers The stem is pulled until it snaps off and the remaining projecting part is trimmed flush with the head. Give examples self plugging mechanical lock rivets. - Answers CherryLOCK, CherryMAX, CherrySST, HulkLOCK and OLYMPIC-LOCK. What methods are used in forming sheet metal? - Answers shrinking, stretching, bumping, crimping, and folding What factors are used to determine setback? - Answers Radius of the bend and thickness of the material What calculation must be made when bending sheet metal? - Answers Bend allowance and setback. What must be done when two bends intersect to prevent cracking? - Answers Relief holes are drilled at the intersection/corner. What is a joggle? - Answers A joggle is an offset formed on an angle strip to allow clearance for a sheet or extrusion. What is the purpose of lightning holes cut in rib sections? - Answers To reduce weight and increase off stiffness. Describe rivet head markings for A,B,D,AD and DD rivets: - Answers A - Are Plain, B - Have a Cross, D - Have a Raised Dot, AD - Have a Dimple, DD - Have a double dash. What are the correct dimensions on a properly formed rivet head.(shop head - Answers 1 ½ the shank diameter and ½ the shank of diameter hight. How do you determine the proper material to be used for a repair of an all metal aircraft? - Answers Use the same type and thickness of the material that was used in the original structure. What is the single row spacing and edge distance for protunding head rivets? - Answers Edge 2 x diameter; Spacing 3 x diameter. Describe the criteria for replacement of a 2024 rivet with a 2117 rivet for general repairs. - Answers For 5/32 or less diameter, use the next larger size rivet 2117 and the edge/spacing distance meet the minimum requirements. What is the major type of damage to aluminum structures that is caused by exposure to the weather? - Answers corrosion What is the difference between the tools required to pull a CherryLOCK rivet and a CherryMAX rivet? - Answers CherryLOCK rivets require a tool for each different size and head shape, while one pulling tool will set any size CherryMAX rivet. How can a mechanic determine whether the countersink for a flush rivet should be dimpled or drilled? - Answers By the thickness of the top sheet; thin sheets are dimpled while thick sheets may be countersunk. What action is taken to prevent cracks from forming while dimpling magnesium or some hard sheet metals - Answers Hot dimpling equipment is used to preheat and soften the metal before the dimple is formed. What type of damage can occur when using a rivet set that does not properly fit the rivet? - Answers The rivet head or sheet metal may be damaged. Why is it important to use the proper bucking bar when performing sheet metal riveting? - Answers Bucking bar too large or heavy - Difficult to control and you can damage the sheet metal. Bucking bar too light - Will not properly upset the rivet before work hardening occur. What procedures should be followed to properly remove a solid-shank rivet? - Answers center punch the rivet, drill to the base of the head with the same size or 1 size smaller drill bit, use a pin punch to remove rivet head. Which of the five stresses is the most common cause of rivet failure? - Answers shear WOOD STRUCTURES - Answers How would you inspect wood for rot (decay)? - Answers Inspect for a dark discoloration of the wood surface or gray stains along the grain. What three forms of wood are used in aircraft? - Answers Solid, laminated, and plywood. What is a laminated wood assembly? - Answers Two or more layers glued together with the grain of all layers approximately parallel. How is aircraft plywood constructed? - Answers Made of an odd number of the thin plies and the grains of each layer placed 90° with the adjacent ply or plies What specie of wood is used as a standard for strenght? - Answers spruce Are hard knots acceptable? - Answers Yes within the limits of ac 43.13-1a Why is compression wood NOT acceptable? - Answers It is very prejudicial to strength. What type of glue may have been used in OLDER AIRCRAFT construction that requires careful inspection to detect deterioration? - Answers Casein glue. What types of glues are used in MODERN AIRCRAFT wood structure repair? - Answers Resorcinol glue, Phenol-formaldehyde glue, and epoxy resin glue. What is the minimum °F for curing wood joints with resin glue - Answers 70°F or as specified by the glue manufacturer. Why it is important to consider the open-assembly time when gluing wooden structures? - Answers Because if the maximum open-assembly time is exceeded the joint may fail since the glue my begin setting up before the joint is assembled. Why it is important to apply the proper clamping pressure to a glue joint? - Answers Clamping forces the air out, brings the wood surfaces together evenly and in part responsible for the strength of the glue line. Describe the acceptable methods used to repair enlongated bolt holes found in a wooden wing spar: - Answers Remove the damaged section and splice in a new section or replace the entire spar. Describe the characteristics of a scarf joint: - Answers The pieces are tapered or beveled on a slope of 1 to 10 or 1 to 12 What are the results of insuficient gluing pressure? - Answers Thick glue and a weak joint. What methods are used to apply pressure to wood glue joints? - Answers Clamps, Brads, Nails, Elastic Straps, Weight, Vacuum Bags, Screws, Electric and Hydraulic power presses. What type of joint is used in splicing structural members? - Answers A scarf joint. What areas of a wood spar may NOT be spliced? - Answers Under a wing attachment, landing gear, engine mount, and lift strut fittings What are the two primary uses for plywood in aircraft construction? - Answers Gusset plates and aircraft skin. Provide examples of at least three types of plywood skin repair: - Answers Scarf, surface, plug, splayed and scarfed patches What type of patch should be used to repair small holes in thin plywood skinif the skin is less than 1/10 inch thick? - Answers A splayed patch. Why must the beveled cut accurate on both pieces of wood being repaired with a scarfed joint? - Answers The pieces must match exacly to ensure a tight glue joint Name at least three diferent types of defects found in wood: - Answers Knots, checks, decay, Splits, pitch pockets, curly grain, cross grain, dry rot. Why should the various pieces of wood be kept in a room for at least 24 hours prior to joining? - Answers To allow moisture content to equalize, minimizing dimensional changes in the wood. What is the maximum number of splices that should be made to any one spar? - Answers two Always splice and reinforce plywood webs with what type of wood? - Answers The same type of plywood as the original Why are light steel bushings somethimes used in wooden structures? - Answers To prevent crushing the wood when the bolts are tightened. What method will prevent a patch and a plywood pressure plate from adhering together due to extruding glue from the patch? - Answers The use of waxed paper or vinyl plastic between the patch and pressure plate. Name several facings and core material used in bonded honeycomb structures intended for special applications: - Answers Stainless steel, titanium, magnesium, plywood, glass, nylon, and cotton cloth. Describe the construction of a bonded honeycomb structure: - Answers It is a laminated structure that has a solid facing bonded to either side of a core consisting of open, six-sided cells. What must be done with a damaged area in a bonded honeycomb structure prior to beginning repairs? - Answers Inspect the area, determine the damage prior to removing the affected area When are mineral streaks acceptable? - Answers If inspection fails to reveal any decay Why is it necessary to examine all strains and discoloration? - Answers To determine if the stains are harmless, preliminary or advanced decay. What types of glues are used in aircraft wood structure repair? - Answers Casein, epoxies, plastic resin, resorcinol glue. drill bit used for drilling composites should operate at approximately what speed? - Answers 20.000 rpm. What are the most common causes for delamination of a composite structure? - Answers Sonic vibration, expansion of internal moisture, liquid leakage, and a manufacturing error. What type of defect in, or damage to, a bonded honeycomb structure can be repaired using the potted repair method? - Answers Filling a hole. Name some factors that cause crazing in transparent plastic Windows and windshields: - Answers UV light, stress, solvents, improper handling How should a hole be drilled in Plexiglas to avoid damage to the hole when the drill breaks through to the underside? - Answers Back up the plastic with a piece of wood and feed the drill slowly. FLIGHT CONTROLS - Answers What flight control surfaces are in the primary group? - Answers The ailerons, elevators, and rudder. What are the three axes of an aircraft - Answers Vertical, longitudinal and lateral What is the purpose of vortex generators - Answers To provide for boundary layer air control. What is a servo trim tab? - Answers It is an auxiliary control, positioned by the movement of a cockpit control and designed to create aerodynamic forces to assist in moving a control surface What is a balance trim tab - Answers An auxiliary control designed to create aerodynamic forces to assist in moving a control surface. What are three mechanical methods used to actuate flight control systems - Answers Cable, push-pull and torque tube What is a Spring Tab? - Answers It is an auxiliary control designed to aid the movement of a primary control at high speeds when control forces become too high. Name four hight-lift devices. - Answers Leading edge and trailing Flaps,Slots,Slats. What is the purpose of a rotorcraft cyclic pitch control - Answers Change the pitch of the main rotor blades during its cycle of rotation. What is the purpose of the rotorcraft colletive pitch control? - Answers It varies the lift of the main rotor blades simultaneosly. What unit compensates for helicopter main rotor torque - Answers tail rotor What controls a helicopter tail rotor? - Answers Foot pedals Where does breakage of control cables occur most frequently? - Answers where cables pass over pulleys and through fairleads What is a cable fairlead? - Answers A cable guide that prevent the cable from rubbing on the aircraft structure. What are cable tension regulators? - Answers They are mechanical devices that automatically maintain cable tension to compensate for expansion and contraction of the aircraft structure What tools are primarily used to check control surface travel - Answers Protactors, rigging fixures, contour templates and rules. What items must be know before using a typical cable rigging chart - Answers The cable size and ambient temperature What should control surfaces be locked when an aircraft is parked? - Answers To prevent damage from the wind. Describe some of the tools used to check control surface travel: - Answers A universal propeller protractor or special control surface protractor. LANDING GEAR SYSTEM - Answers What is the purpose of main landing gear torque links? - Answers They keep the landing gear pointed in a straight ahead direction What is used to inflate landing gear shock strut? - Answers Dry air or nitrogen What power sources are normally used to retract landing gear systems? - Answers Hydraulic or electrical What prevents a nose landing gear from being retracted with the nosewheel out of the center position? - Answers Nosewheel centering cams or external track. When should a landing gear retraction check be accomplished? - Answers Annual inspection,Replacements, Hard Landings or other programed inspecions. What methods are used for transmitting cockpit control movements to a steering control unit in large aircraft? - Answers Mechanical, electrical, or hydraulic What type of nosewheel steering is provided on small aircraft? - Answers A simple system consisting of mechanical linkage hooked to the rudder pedals What unit prevents nosewheel vibration? - Answers A shimmy damper. What prevents a Split Wheel from leaking air through the inner and outher mating surfaces, or the wheel assembly. - Answers An O'ring between the halves. What is the indication of excessive heating of a wheel bearing? - Answers discoloration What is the purpose of a wheel fusible plug? - Answers Relieve air pressure to prevent tire blowout What are some types of brake actuating systems - Answers Independent master cylinders, boosted brakes and power control-controlled brakes. What is the purpose of power brake debooster? - Answers Reduces hydraulic system high pressure to a lower value for more satisfactory brakes action. What is the purpose of an anti-skid system - Answers It prevents the wheels to skid or lock during brakes attempts. What are some methods of bleeding brakes? - Answers gravity and pressure methods What must be accomplished before inspecting a wheel brake system for hydraulic leaks? - Answers Pressurize the system What is the most necessary maintenance function for safe and long aircraft tire service? - Answers Proper inflation What are the effects of under inflation on tires? - Answers Uneven wear near the edge of tread and creep or slip when the brakes are applied. What conditions should a mechanic look for during a regular inspection of the esposed piston section of a landing gear - Answers Cleanliness, damages and proper extension. What safety precaution must be taken when removing a wheel from an axle or when disassembling a wheel? - Answers Verify that the tire is completely deflated before removing a wheel from an axle or before wheel disassembly. HYDRAULIC AND PNEUMATIC SYSTEMS - Answers What are three types of hydraulic fluids? - Answers Vegetal, Mineral and Phosphate Esters. Which color mineral base and phosphate-ester hydraulic fluids have? - Answers Mineral -Red / Phosphate ester - Light purple. What happens to plastic resins, vinyl compositions, lacqers, and oil base paints if exposed to a phosphate ester base hydraulic fluid such as skydrol? - Answers Damaged, softened and/or peeled. What precautions should be taken to minimize contamination during replacement of a hydraulic unit? - Answers All lines should be plugged or capped after disconnecting. What would cause a hydraulic filter to go into open by-pass, allowing unfiltred fluid into the system? - Answers A clogged filter What are two types of engine-driven hydraulic pumps? - Answers Constant delivery and variable delivery What feature is built into a hydraulic pump-drive system to prevent engine damage in the event of pump seizure or overload? - Answers A shear action in the pump drive shaft occurs. What is the purpose of a pressure relief valve - Answers To limit the amount of pressure, preventing failure of the system components. What is the purpose of a pressure regulator - Answers to manage the output of the pump to maintain system pressure and allow the pump to turn without resistance What is used in some hydraulic systems to supplement the power pump when several units are operated at the same time? - Answers An accumulator. What are the different types of accumulators - Answers Piston, diaphragm, and bladder. What must be accomplished with any accumulator prior to disassembling? - Answers Make sure that the air or preload has been discharged. For what purposes are pneumatic systems used in some aircrafts? - Answers To operate brakes, doors, drive pumps, and engine starting. What are sources of pneumatic power? - Answers Storage bottles, vane-type pumps, and turbine engine compressors. How does a gear-type power pump operate? - Answers Two meshed gears are driven by a power unit rotate in a housing. Fluid is carried around the outside of the gears and delivered to the outlet side as the gears rotate. What happens to excessive pressure in a pneumatic system - Answers A relief valve will bleed it to the atmosphere What is the purpose of restrictors that are used in aircraft pneumatic systems? - Answers To control the rate of the airflow Why should a pneumatic system be purged periodically? - Answers To remove contamination and moisture Name several sources used to develop hydraulic pressure: - Answers Hand pumps, engine-driven pumps, and electrically driven pumps. What types of components or systems are pneumatically operated in some aircraft - Answers Landing gear, brakes, flaps, Name several sources of pneumatic power: - Answers Storage bottles, engine bleed air , engine-driven compressors or vane-type pumps. CABIN ATMOSPHERE CONTROL SYSTEMS - Answers How does a continuous-flow oxygen system operate? - Answers oxygen flows from a charged cylinder through a high pressure line to a reducing valve and to mask outlets How does a basic pressure-demand oxygen system operate? - Answers oxygen flows from a charged cylinder to a pressure-demand regulator, adjustable by each crewmember What type of oxygen must be used in aircraft? - Answers Aviators breathing oxygen 4. What must be accomplished if an oxygen system has been open to atmosphere for 2 hours or more? - Answers It must be purged to remove the moisture. What is used to purge oxygen lines of moisture? - Answers Dry nitrogen, dry air and/or oxygen What safety precautions should be observed when servicing oxygen systems? - Answers Oil free tools, clothing, hands, and adequate eye protection. What are the two groups of independent cabin compressors - Answers Positive-displacement and centrifugal. What is a Roots Blower? - Answers An engine-driven compressor. What method is used by some turbine-powered aircraft for pressurization? - Answers Engine bleed air. What pressurization control unit will regulates the position of an outflow valve? - Answers The cabin pressure controller. What is the principal control of a pressurization system? - Answers An outflow valve What components are used in an air-cycle cooling system? - Answers An expansion turbine, heat exchanger and various valves. Describe the basic operating principles that allow an air-cycle system to produce cool air. - Answers (1)Engine air bleed is cooled in the primary heat exchanger, (2)compressed cooled again in the second heat exchanger (3)then goes to a turbine that extracts the energy and pressure of the air droping the air temperature. How does a water separator remove moisture from the air? - Answers The moist air passes through vanes that swirl the air and the droplets are collected and drained. In what significant way is a vapor-cycle cooling system different from an air-cycle system? - Answers Vapor-Cycle uses Freon. What components are in a vapor-cycle cooling? - Answers a receiver dryer, evaporator, compressor, condenser, and expansion valve Why is oil added to a vapor-cycle freon system? - Answers To seal and lubricate the compressor. What is the function of ventilating air in a combustion heater? - Answers Ventilating air transports the heat from the heater into the cabin and prevents combustion gases from entering the cabin if the combustion chamber develops a crack. Name several methods used on reciprocating engine aircraft for providing heated cabin air: - Answers Exhaust shroud heat exchangers, combustion heaters, and electric heaters. What are sources of ventilating air in a combustion heater? - Answers A blower, ram air, or cabin compressor AIRCRAFT INSTRUMENT SYSTEM - Answers What can be used to static check a manifold pressure indicator gauge? - Answers Current atmospheric pressure. What flight instruments are usually connected to a pilot-static system? - Answers Air speed, Rate of climb (vertical speed indicator), altimeter and mach meter. Why should you avoid cleaning obstructions from the sensing holes in a pitot-static system? - Answers The holes are aerodynamically critical. What causes an electric-driven gyro rotor to tilt when the aircraft turned? - Answers Gyroscopic precession What indication erros may be found in altimeters? - Answers Scale errors, hysteresis (lags), friction and installation. What aircraft instrument can be used to check manifold pressure gauge for proper indication? - Answers The sensitive altimeter. What is a synchro-type remote indicating system? - Answers A system that transmits information from one point to another point (flap position). What does a tachometer indicate? - Answers Crankshaft RPM or Main Turbine rotor speed IN % of RPM. Where does an electrical resistance temperature indicator receive a signal? - Answers From a temperature bulb OR sensitive element. What type of indicating system is a turbine-engine exhaust gas temperature system? - Answers A thermocouple-type system. What methods are used to drive turn-and-bank/slip (gyroscopic turn indicator) indicators? - Answers Vacuum, air pressure, or electricity Who is authorized to apply the range markings to an instrument dial face? - Answers The manufacturer or a certified instrument repair station. What does a yellow arc on an instrument dial indicate? - Answers caution Why are slippage marks used on instruments glass covers? - Answers To indicate glass rotation in the bezel. What refrences should be consulted to determine the proper range markings for aircraft instruments? - Answers The aircraft maintenance manual, Aricraft flight manual, TCDS. Or Aircraft Specifications. What is required after replacement of components connected to a pitot-static system? - Answers leak test What is the meaning of swinging a compass? - Answers correcting for deviations by adjusting the compensating magnets Name at least two items that should be looked for during an inspection of a magnetic compass? - Answers ( 1 ) Security of attachment ; ( 2 ) Correct readings at various headings ; ( 3 ) The bowl should be filled with liquid and not contain any bubbles or discoloration ; ( 4 ) The scale should be readable ; ( 5 ) Moving parts should work easily . In what way do magnetic fields generated by electrical equipment and steel parts in the airplane affect a magnetic compass? - Answers Magnetic fields deflect the compass from correct alignment with the earth's magnetic field.