### Q121: What type of defect causes a loss of airworthiness? ^t20q121 - A) A scratch on the exterior paint. - B) Damage to load-bearing structural parts. - C) A crack in the canopy plastic. - D) A dirty wing leading edge. **Correct: B)** > **Explanation:** Airworthiness is fundamentally determined by the structural integrity of load-bearing components (main spar, wing attachment fittings, fuselage frames, control system connections). Damage to these parts compromises the aircraft's ability to sustain flight loads safely and constitutes a loss of airworthiness, grounding the aircraft until repairs are made. Option A (paint scratch) is cosmetic. Option C (canopy crack) may affect visibility but is not structural. Option D (dirty leading edge) reduces aerodynamic performance but does not affect structural airworthiness. ### Q122: The loaded mass falls below the minimum load required by the load sheet. What should be done? ^t20q122 - A) Change the pilot's seat position. - B) Modify the incidence angle of the elevator. - C) Load ballast weight until the minimum load is reached. - D) Set the trim to a nose-down position. **Correct: C)** > **Explanation:** When the actual loaded mass falls below the minimum required by the load sheet, ballast weight (typically lead) must be added in the designated ballast compartment to bring the total mass up to the minimum. This ensures the centre of gravity remains within approved limits. Option A (seat position) does not add mass. Option B (elevator incidence) is a major structural modification, not an operational solution. Option D (trim setting) compensates aerodynamically but does not address the underlying mass and CG problem. ### Q123: Water ballast increases wing loading by 40%. By what percentage does the minimum speed of the glider increase? ^t20q123 - A) 200% - B) 18% - C) 100% - D) 40% **Correct: B)** > **Explanation:** Minimum speed (stall speed) is proportional to the square root of wing loading: Vs is proportional to the square root of (W/S). If wing loading increases by 40% (factor 1.4), stall speed increases by the square root of 1.4, which equals approximately 1.183, or an 18.3% increase. This square-root relationship is fundamental to understanding the performance effects of water ballast. Option A (200%) is far too high. Option C (100%) would require quadrupling the wing loading. Option D (40%) incorrectly assumes a linear relationship. ### Q124: The maximum mass from the load sheet has been exceeded. What action is required? ^t20q124 - A) Set the trim to nose-up. - B) Set the trim to nose-down. - C) Reduce the load. - D) Increase the speed by 15%. **Correct: C)** > **Explanation:** When the maximum mass is exceeded, the only correct action is to reduce the load -- remove water ballast, baggage, or use ballast reduction until the total mass falls within the approved limit. Exceeding maximum mass means structural limits may be reached at lower G-forces than designed for. Option A and Option B (trim adjustments) do not address structural overloading. Option D (speed increase) would actually increase structural loads, making the situation more dangerous. ### Q125: What is meant by a torsion-stiffened leading edge? ^t20q125 - A) A special shape given to the leading edge. - B) A portion of the main spar designed to resist torsion forces. - C) The point where the torsion moment on a wing begins to decrease. - D) A leading edge planked on both sides (from edge to spar) to resist torsion forces. **Correct: D)** > **Explanation:** A torsion-stiffened leading edge (D-box or D-nose) is created by planking (covering with skin) both the upper and lower surfaces of the wing from the leading edge back to the main spar. This creates a closed cross-section box that efficiently resists torsional (twisting) loads on the wing. Option A describes a shape, not a structural concept. Option B confuses the leading edge structure with the spar. Option C describes a theoretical analysis point, not a construction feature. ### Q126: Where can information about maximum permitted airspeeds be found? ^t20q126 - A) POH, approach chart, and vertical speed indicator. - B) Airspeed indicator, cockpit panel, and AIP part ENR. - C) POH and the briefing room notice board. - D) POH, cockpit panel, and airspeed indicator. **Correct: D)** > **Explanation:** Maximum permissible airspeeds (VNE, VNO, VFE) are documented in three locations: the Pilot's Operating Handbook (POH/AFM), the cockpit instrument panel (placard), and the airspeed indicator itself (via red line, arcs, and markings). Option A incorrectly includes approach charts and the VSI. Option B incorrectly includes the AIP ENR, which contains airspace information, not aircraft-specific speed limits. Option C includes the briefing room, which is informal. ### Q127: The airspeed indicator is unserviceable. When may the aircraft be operated again? ^t20q127 - A) Only for a circuit pattern. - B) If no maintenance facility is available nearby. - C) When the airspeed indicator is fully functional again. - D) When a GPS with speed readout is used during flight. **Correct: C)** > **Explanation:** The ASI is a mandatory instrument; without it the pilot cannot determine safe operating speeds, stall speed, or structural limits. The aircraft must remain grounded until the ASI is fully functional. No exceptions exist. Option A (circuit pattern only) is not a recognised exception. Option B (no nearby maintenance) does not waive the requirement. Option D (GPS substitute) is inadequate because GPS shows ground speed, which differs from indicated airspeed and cannot be used for aerodynamic safety decisions. ### Q128: During a left turn, the yaw string deflects to the left. What correction centres it? ^t20q128 - A) Less bank, more rudder in the direction of the turn. - B) Less bank, less rudder in the direction of the turn. - C) More bank, less rudder in the direction of the turn. - D) More bank, more rudder in the direction of the turn. **Correct: C)** > **Explanation:** In a left turn, a yaw string deflecting to the left indicates a slip -- the aircraft is slipping into the turn due to excessive bank relative to rudder input. To correct a slip, increase bank (to match the turn rate) and reduce rudder in the turn direction (less left rudder, as too much rudder is driving the nose too far into the turn). Option A corrects a skid, not a slip. Options B and D use incorrect combinations for slip correction. ### Q129: What is the purpose of winglets? ^t20q129 - A) To increase the effective aspect ratio. - B) To increase lift and turning maneuverability. - C) To improve gliding performance at high speed. - D) To reduce induced drag. **Correct: D)** > **Explanation:** Winglets are vertical or near-vertical extensions at the wingtips designed to reduce induced drag by weakening the wingtip vortex -- the primary source of induced drag on any finite wing. By disrupting the spanwise flow around the tip, winglets reduce the energy lost in the vortex system. Option A (effective aspect ratio) is a related effect but not the primary purpose. Option B (lift and manoeuvrability) is incorrect -- winglets do not significantly increase lift. Option C (high-speed performance) is not the primary benefit; induced drag reduction helps most at lower speeds. ### Q130: What does dynamic pressure depend on directly? ^t20q130 - A) Air density and lift coefficient. - B) Lift coefficient and drag coefficient. - C) Air pressure and air temperature. - D) Air density and airflow speed squared. **Correct: D)** > **Explanation:** Dynamic pressure is defined by the equation q = 1/2 rho v-squared, where rho is air density and v is airflow velocity. It depends directly on these two variables. Option A and Option B involve aerodynamic coefficients, which are effects that result from dynamic pressure, not its determinants. Option C (pressure and temperature) influences density indirectly (through the ideal gas law) but are not the direct parameters in the dynamic pressure formula. ### Q131: The airspeed indicator, altimeter, and vertical speed indicator all give incorrect readings simultaneously. What is the likely cause? ^t20q131 - A) Failure of the electrical system. - B) A leak in the compensation vessel. - C) Blockage of the static pressure lines. - D) Blockage of the Pitot tube. **Correct: C)** > **Explanation:** All three instruments -- ASI, altimeter, and VSI -- are connected to the static pressure system. If the static pressure line is blocked (by ice, water, or a protective cover left on), all three will simultaneously give erroneous readings. Option A (electrical failure) does not affect these purely pneumatic instruments. Option B (compensation vessel leak) would affect only the VSI. Option D (Pitot tube blockage) would affect only the ASI, not the altimeter or VSI. ### Q132: When should the reference pressure on the altimeter subscale be adjusted? ^t20q132 - A) Once a month before flight operations. - B) Every day before the first flight. - C) After maintenance has been completed. - D) Before every flight, and during cross-country flights. **Correct: D)** > **Explanation:** The altimeter subscale must be set to the correct QNH/QFE before every flight to ensure accurate altitude readings. During cross-country flights, QNH changes as the pilot moves between different pressure regions, requiring updates from ATC or ATIS broadcasts along the route. Option A (monthly) would result in dangerous altitude errors. Option B (daily) is insufficient for multiple flights and cross-country work. Option C (after maintenance only) ignores the continuous need for pressure updates. ### Q133: The term "inclination" is defined as... ^t20q133 - A) The angle between the aircraft's longitudinal axis and true north. - B) The angle between the Earth's magnetic field lines and the horizontal plane. - C) Deviation induced by electrical fields. - D) The angle between magnetic north and true north. **Correct: B)** > **Explanation:** Magnetic inclination (or dip) is the angle between the Earth's magnetic field vector and the local horizontal plane. At the magnetic equator, field lines are horizontal (0 degrees dip); at the magnetic poles, they are vertical (90 degrees dip). This dip causes turning and acceleration errors in the magnetic compass. Option A describes aircraft heading. Option C describes deviation from onboard equipment. Option D describes magnetic variation/declination. ### Q134: As air density decreases, the true airspeed at stall increases. How should a final approach be flown on a hot summer day? ^t20q134 - A) At a decreased indicated airspeed (IAS). - B) At an unchanged indicated airspeed (IAS). - C) At an increased indicated airspeed (IAS). - D) At an additional speed as specified in the POH. **Correct: B)** > **Explanation:** Aerodynamic behaviour (lift, stall, control effectiveness) depends on dynamic pressure, which is what IAS reflects. Stall occurs at the same IAS regardless of air density. On a hot day, lower density means TAS is higher for the same IAS, but the wing "feels" the same dynamic pressure. Therefore, the approach should be flown at the same IAS as in standard conditions. Option A (decreased IAS) would bring the aircraft closer to stall. Option C (increased IAS) is unnecessarily conservative. Option D adds complexity not needed when understanding the IAS/TAS relationship. ### Q135: The load factor n represents the ratio between... ^t20q135 - A) Drag and lift. - B) Thrust and drag. - C) Lift and weight. - D) Weight and thrust. **Correct: C)** > **Explanation:** Load factor n = Lift / Weight. In level flight n = 1. In manoeuvres where lift exceeds weight (turns, pull-ups), n increases above 1. The load factor is critical for structural calculations -- gliders have certificated maximum positive and negative load factors that define their structural envelope. Option A (drag/lift) is not a standard aerodynamic ratio. Option B (thrust/drag) relates to propulsion efficiency. Option D (weight/thrust) is irrelevant for gliders which normally have no engine. ### Q136: Static pressure is defined as the pressure... ^t20q136 - A) Inside the aircraft cabin. - B) Sensed by the Pitot tube. - C) Resulting from orderly movement of air particles. - D) Of undisturbed airflow. **Correct: D)** > **Explanation:** Static pressure is the ambient atmospheric pressure of undisturbed air, acting equally in all directions at a given point regardless of airflow velocity. It is sensed by flush static ports on the fuselage. Option A (cabin pressure) is a different, regulated pressure in pressurised aircraft. Option B (Pitot tube) senses total pressure, which includes both static and dynamic components. Option C describes dynamic pressure characteristics related to directed airflow, not the omnidirectional nature of static pressure. ### Q137: The term "inclination" refers to... ^t20q137 - A) The angle between the aircraft's longitudinal axis and true north. - B) Deviation caused by electrical fields. - C) The angle between magnetic north and true north. - D) The angle between the Earth's magnetic field lines and the horizontal plane. **Correct: D)** > **Explanation:** Magnetic inclination (dip) is the angle between the Earth's total magnetic field vector and the local horizontal plane. At the magnetic equator the field is horizontal (0 degrees); at the magnetic poles it is vertical (90 degrees). This inclination is the root cause of compass turning errors and acceleration errors. Option A describes heading relative to true north. Option B describes electromagnetic deviation from onboard equipment. Option C describes magnetic variation/declination.