A&P - Airframe Oral Exam (Jeppesen) Questions and answers.

What is the function of a vortex generator? It is designed to delay of prevent separation of the boundary layer. What are the three axes of an airplane? Longitudinal, lateral, and vertical. What are the three primary flight controls of an aircraft? The ailerons, elevators, and rudder. Name several secondary flight controls and describe their general purpose? Secondary flight controls consist of various types of trim tabs such as balance tabs, anti-servo and servo tabs, and spring tabs. Their function is to assist the pilot in moving the controls and to trim the aircraft to fly hands-off. Name several types of auxiliary flight controls and describe their general purpose? The auxiliary flight controls consist of the various high-lift devices used during low-speed flight such as leading and trailing edge flaps, slats, slots, speed brakes, etc. What is a servo trim tab? It is an auxiliary control, positioned by the movement of a primary control and designed to create aerodynamic forces to assist in moving a control surface. What is a spring tab? It is an auxiliary control designed to aid the movement of a primary control at high speeds when control forces become too high. What is a balance trim tab? It is an auxiliary control designed to create aerodynamic forces to assist in moving a control surface. The tab is positioned by a control rod connected to the fixed surface on the same side as the horn an the tab. What are four most common types of high lift devices? Leading and trailing edge flaps, slats, and slots. Describe some of the tools used to check control surface travel? A universal propeller protractor or specal control surface protractor. Name three mechanical methods by which flight control systems may be actuated. Cables, push-pull rods, and torque tubes. What is a fairlead? It is a device to prevent a cable from rubbing on the aircraft strcture. What are the most likely places for a control cable to wear or break? Where the cables pass over pulleys or through fairleads. What information is required before a cable rigging chart can be used? The ambient temperature and the cable size. What is the function of a cable tension regulator? It automatically adjusts the cable tension to compensate for expansion and contraction in the aircraft structure. Describe the function of rotorcraft collective pitch control. The collective control causes each rotor blade to change its pitch angle by the same amount, thus increasing or decreasing the lift produced by the rotor. Describe the function of a rotorcraft cyclic pitch control. The cyclic control tilts the main rotor disc by by changing the pitch angle of each rotor blade during its cycle of rotation, which causes the helicopter to move in the direction the rotor tilts. What mechanism is most commonly used to compensate for the torque produced by the main rotor of a helicopter? The tail (or anti-torque) rotor. How is the amount of thrust produced by the tail rotor controlled? By moving the foot pedals. Why should a control surface be locked when an aircraft is parked? To prevent damage from the wind. What is the major type of damage to aluminum structures that is caused by exposure to the weather? Corrosion. Name several method for forming sheet metal. Bending or folding, stretching, shrinking, bumping, and crimping. What are the dimensions of a properly formed rivet head? The head should be 1-1/2 times the shank diameter in width and 1/2 the shank diameter in height. Describe the markings found on the heads of A, B, D, AD, and DD rivets? A rivets are plain, B rivets have a cross, D rivets have a raised dot, AD rivets have a dimple, and DD rivets have a double dash. What happens to the stem of a self-plugging (friction lock) rivet when the rivet is installed? The stem is pulled until it snaps off and the remaining projecting part is trimmed flush with the head. Name at least three types of self-plugging mechanical lock rivets. CherryMAX, CherryLOCK, OLYMPIC-LOK, and HuckLok. What is the difference between the tools required to pull a CherryLOCK rivet and a CherryMAX rivet? CherryLock rivets require a tool for each different size and head shape, while one pulling tool will set and size CherryMAX rivet. Which of the five stresses is the most common cause of rivet failure? Shear. If a 2024 rivet must be replaced with a 2117 rivet, how do you determine the size to be used? For 5/32" or smaller diameter, use the next larger size 2117 rivet, assuming that the edge distance and spacing meet the minimum requirements. Describe the process for determining the total length of a solid rivet for a particular installation. Add the grip length (thickness or the materials being joined) plus 1-1/2 times the rivet diameter. What minimum edge distance and spacing should be used for a single row of protruding head rivets? Not less than two rivet diameters from the edge and not less than three rivet diameters apart. How can a mechanic determine whether the countersink for a flush rivet should be dimpled or drilled? 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? 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? If the radius of the set is too small, the rivet head may be damaged, whereas a set with an over-sized radius may cause damage to the sheet metal. Why is it important to use the proper size and weight bucking bar when performing sheet metal riveting? If a bucking bar is too large or heavy it may be difficult to control and may cause damage to the surrounding structure, whereas a bucking bar that is too light will not properly upset the rivet before work hardening occurs.