# 20 - Aircraft General Knowledge > Source: EASA ECQB-SPL (new questions not in existing set) | 27 questions --- ### Q1: What is a cause for the dip error on the direct-reading compass? ^q1 - A) Acceleration of the airplane - B) Temperature variations - C) Deviation in the cockpit - D) Inclination of earth's magnetic field lines **Correct: D)** > **Explanation:** The dip error (also called northerly turning error or acceleration error) in a direct-reading magnetic compass is caused by the inclination of the Earth's magnetic field lines, which dip downward toward the magnetic poles at an angle to the horizontal. This causes the compass card's pivot point and the magnet system to be offset, leading to errors particularly during turns and accelerations. Temperature variations (B), deviation (C — a different compass error caused by onboard magnetic fields), and acceleration per se (A) are separate effects; the root physical cause of dip error is the field line inclination. ### Q2: The Caution Area is marked on an airspeed indicator by what color? ^q2 - A) Red - B) Green - C) White - D) Yellow **Correct: D)** > **Explanation:** On an airspeed indicator, the yellow arc marks the caution range — the speed band between VNO (maximum structural cruising speed) and VNE (never-exceed speed). Flight in this range is permitted only in smooth air. Red (A) marks VNE (the never-exceed redline). Green (B) marks the normal operating range. White (C) marks the flap operating speed range. ### Q3: What difference in altitude is shown by an altimeter, if the reference pressure scale setting is changed from 1000 hPa to 1010 hPa? ^q3 - A) Zero - B) 80 m less than before - C) 80 m more than before - D) Values depending on QNH **Correct: C)** > **Explanation:** The altimeter measures atmospheric pressure and converts it to altitude using the ISA pressure-altitude relationship. Increasing the QNH setting by 10 hPa causes the altimeter to indicate approximately 80 m more altitude (since 1 hPa corresponds to roughly 8 m at sea level). The reading is not zero (A), not less (B), and is not dependent on the QNH value itself (D) — the conversion factor is fixed by the ISA model. ### Q4: The altimeter's reference scale is set to airfield pressure (QFE). What indication is shown during the flight? ^q4 - A) Altitude above MSL - B) Height above airfield - C) Airfield elevation - D) Pressure altitude **Correct: B)** > **Explanation:** QFE is the atmospheric pressure at aerodrome elevation. When an altimeter is set to QFE, it reads zero on the ground at the aerodrome and shows height above that aerodrome during flight. It does not show altitude above MSL (A — that would be QNH), the aerodrome elevation itself (C), or pressure altitude (D — that requires setting 1013.25 hPa). ### Q5: A vertical speed indicator connected to a too big equalizing tank results in... ^q5 - A) Mechanical overload - B) No indication - C) Indication too low - D) Indication too high **Correct: D)** > **Explanation:** A total energy compensated vertical speed indicator (TE-VSI) uses a specially shaped nozzle (TE probe) to cancel out changes in indicated climb/sink caused by changes in airspeed (energy exchange). If the compensating tank is too large, the compensation overcorrects and the instrument indicates a sink rate that is larger than the actual sink rate — i.e., too high a reading. A too-large tank does not cause mechanical overload (A), no indication (B), or under-reading (C). ### Q6: A vertical speed indicator measures the difference between... ^q6 - A) Total pressure and static pressure. - B) Dynamic pressure and total pressure. - C) Instantaneous static pressure and previous static pressure. - D) Instantaneous total pressure and previous total pressure. **Correct: C)** > **Explanation:** A vertical speed indicator (variometer) works by measuring the difference between the current (instantaneous) static pressure and the pressure stored in an internal chamber (the reference or compensating vessel) through a calibrated restriction. As altitude changes, the instantaneous static pressure diverges from the stored pressure, deflecting a diaphragm or capsule. It does not measure total vs. static (A — that is the airspeed indicator), dynamic vs. total (B), or total pressure changes (D). ### Q7: What engines are commonly used with Touring Motor Gliders (TMG)? ^q7 - A) 2 plate Wankel - B) 2 Cylinder Diesel - C) 4 Cylinder 2 stroke - D) 4 Cylinder; 4 stroke **Correct: D)** > **Explanation:** Touring Motor Gliders (TMG) are typically equipped with a conventional four-cylinder, four-stroke piston engine (such as Rotax 912 or Limbach engines), which provides good power-to-weight ratio, reliability, and fuel efficiency for the self-launch and cruise requirements of a TMG. Wankel (A), diesel two-cylinder (B), and four-cylinder two-stroke (C) engines are either not common or not used in certified TMG types. ### Q8: What is the meaning of the yellow arc on the airspeed indicator? ^q8 - A) Cautious use of flaps or brakes to avoid overload. - B) Speed for best glide can be found in this area. - C) Flight only in calm weather with no gusts to avoid overload. - D) Optimum speed while being towed behind aircraft. **Correct: C)** > **Explanation:** The yellow arc on an airspeed indicator marks the caution speed range between VNO and VNE. Flight in this range is only permitted in smooth air with no gusts, because at these higher speeds turbulence-induced loads could exceed structural limits. It does not indicate a flap/brake limitation range (A), best glide speed (B — that is a specific point, not an arc), or towing speed (D). ### Q9: An energy-compensated vertical speed inicator (VSI) shows during stationary glide the vertical speed... ^q9 - A) Of the glider through surrounding air - B) Of the airmass flown through. - C) Of the glider plus movement of the air - D) Of the glider minus movement of the air. **Correct: B)** > **Explanation:** A total-energy compensated variometer (TE variometer) cancels the effect of the pilot's control inputs on indicated vertical speed by accounting for changes in kinetic energy. During a steady (stationary) glide with no vertical air movement, it correctly shows the vertical speed of the airmass being flown through (i.e., zero in still air, or the actual thermal/sink value). It does not show the glider's speed through the airmass uncompensated (A), the combined glider plus airmass movement (C), or a subtracted value (D). ### Q10: During a right turn, the yaw string is drawn to the left from center position. By what rudder input can the string be centered again? ^q10 - A) Less bank, less rudder in turn direction - B) Less bank, more rudder in turn direction - C) More bank, less rudder in turn direction - D) More bank, more rudder in turn direction **Correct: B)** > **Explanation:** During a right turn, if the yaw string deflects to the left, the nose is yawing left relative to the turn — this indicates a skidding turn (too little bank and too little inside rudder, or adverse yaw). To centre the string, the pilot needs to increase rudder in the turn direction (right rudder) to bring the nose around, and reduce bank slightly to decrease the centrifugal skid tendency. Options A, C, and D either use the wrong rudder direction or wrong bank correction for this skid condition. ### Q11: What kind of defect results in loss of airworthiness of an airplane? ^q11 - A) Dirty wing leading edge - B) Crack in the cabin hood plastic - C) Scratch on the outer painting - D) Damage to load-bearing parts **Correct: D)** > **Explanation:** Airworthiness of an aircraft is fundamentally determined by the structural integrity of load-bearing components (main spar, wing attachment, fuselage frames, control system attachment points). Damage to these parts compromises the aircraft's ability to sustain flight loads and constitutes a loss of airworthiness. A dirty leading edge (A) reduces performance but is not an airworthiness defect. A cracked canopy (B) and a scratch on paint (C) are cosmetic or minor defects that do not affect structural integrity. ### Q12: The mass loaded on the plane is lower than the minimum load required by the load sheet. What action has to be taken? ^q12 - A) Trim aircraft to "pitch down" - B) Change pilot seat position - C) Change incident angle of elevator - D) Load ballast weight up to minimum load **Correct: D)** > **Explanation:** The load sheet (weight and balance document) specifies a minimum pilot weight to ensure the centre of gravity remains within approved limits. If the actual pilot weight is below the minimum, ballast must be added (typically in the ballast area specified by the POH) to bring the total loaded mass up to the minimum required value. Adjusting trim (A, C) does not address the underlying CG/mass problem, and changing seat position (B) is not a standard corrective action for under-weight loading. ### Q13: Water ballast increases wing load by 40%. By what percentage does the minimum speed of the glider plane increase? ^q13 - A) 100% - B) 40% - C) 200% - D) 18% **Correct: D)** > **Explanation:** Minimum speed (stall speed) is proportional to the square root of wing loading: Vs ∝ √(W/S). If wing loading increases by 40% (factor 1.4), stall speed increases by √1.4 ≈ 1.183, i.e., approximately 18.3%. A 40% speed increase (B) would require a 96% increase in wing loading, 100% (A) would require a quadrupling of wing loading, and 200% (C) is far too large. Only the square-root relationship gives approximately 18%. ### Q14: The maximium load according load sheet has been exceeded. What action has to be taken? ^q14 - A) Increase speed by 15% - B) Reduce load - C) Trim "pitch-down" - D) Trim "pitch-up" **Correct: B)** > **Explanation:** If the actual loaded mass exceeds the maximum allowed mass from the load sheet, the only correct action is to reduce the load (remove ballast, water ballast, baggage, or have a lighter pilot). Exceeding maximum mass means structural load limits may be reached at lower G-loads or airspeeds. Increasing speed (A) or adjusting trim (C, D) does not address the structural overload problem. ### Q15: What is referred to as torsion-stiffed leading edge? ^q15 - A) The part of the main cross-beam to support torsion forces. - B) Special shape of the leading edge. - C) The point where the torsion moment on a wing begins to decrease. - D) Both-side planked leading edge (from edge to cross-beam) to support torsion forces. **Correct: D)** > **Explanation:** A torsion-stiffened leading edge is a structural design feature in which the leading edge of the wing (from the leading edge to the main spar) is planked (covered) on both upper and lower surfaces, creating a closed-section D-box that resists torsional (twisting) loads. This is not a spar component (A), not merely a shape descriptor (B), and not a reference to a torsion moment distribution point (C). ### Q16: Information about maxmimum allowed airspeeds can be found where? ^q16 - A) Airspeed indicator, cockpit panel and AIP part ENR - B) POH, approach chart, vertical speed indicator - C) POH and posting in briefing room - D) POH, Cockpit panel, airspeed indicator **Correct: D)** > **Explanation:** Maximum permissible airspeeds (VNE, VNO, etc.) are published in the Pilot's Operating Handbook (POH/AFM), displayed on the cockpit instrument panel (placard), and indicated on the airspeed indicator by the red line (VNE) and arc markings. The AIP ENR (A) does not contain aircraft-specific speed limitations. Approach charts and VSI (B) do not show speed limits. The briefing room posting (C) is informal and not authoritative. ### Q17: The airspeed indicator is unservicable. The airplane may only be operated... ^q17 - A) If no maintenance organisation is around. - B) If only airfield patterns are flown - C) When the airspeed indicator is fully functional again. - D) When a GPS with speed indication is used during flight. **Correct: C)** > **Explanation:** The airspeed indicator is a required instrument for safe flight; without it a pilot cannot determine safe operating speeds, stall speed, or structural speed limits. An inoperative airspeed indicator means the aircraft must remain on the ground until the instrument is serviceable. No exception exists for local aerodrome patterns (B) or GPS substitute (D — GPS ground speed is not equivalent to IAS for aerodynamic purposes). Absence of maintenance (A) is irrelevant to the operational requirement. ### Q18: During a left turn, the yaw string is drawn to the left from center position. By what rudder input can the string be centered again? ^q18 - A) More bank, less rudder in turn direction - B) Less bank, more rudder in turn direction - C) Less bank, less rudder in turn direction - D) More bank, more rudder in turn direction **Correct: A)** > **Explanation:** During a left turn, a yaw string deflecting to the left indicates the aircraft is slipping into the turn (too much bank relative to rudder input). To centre the string in a slip, the pilot needs to increase bank to steepen the turn and reduce rudder (less rudder in the turn direction). This is opposite to correcting a skid. Options B, C, and D use incorrect combinations for correcting a slip in a left turn. ### Q19: What is the purpose of winglets? ^q19 - A) To increase efficiency of aspect ratio. - B) Reduction of induced drag. - C) Increase gliging performance at high speed. - D) Increase of lift and turning manoeuvering capabilities. **Correct: B)** > **Explanation:** Winglets are upward (or downward) curving extensions at the wingtip that reduce induced drag by weakening the wingtip vortex — the main source of induced drag on a finite wing. They do not primarily increase aspect ratio efficiency (A — though functionally similar, they are a different mechanism), are not specifically for high-speed performance (C), and do not increase lift or turning agility (D). ### Q20: What does the dynamic pressure depend directly on? ^q20 - A) Lift- and drag coefficient - B) Air density and airflow speed squared - C) Air density and lift coefficient - D) Air pressure and air temperature **Correct: B)** > **Explanation:** Dynamic pressure (q) is defined by Bernoulli's equation as q = ½ρv², where ρ is air density and v is airflow speed. Dynamic pressure depends directly on air density and the square of velocity. Lift and drag coefficients (A) are aerodynamic effects that depend on dynamic pressure, not the other way around. Air pressure and temperature (D) influence density indirectly but are not the direct parameters in the formula. ### Q21: Airspeed indicator, altimeter and vertical speed indicator all show incorrect indications at the same time. What error can be the cause? ^q21 - A) Blocking of static pressure lines. - B) Leakage in compensation vessel. - C) Blocking of pitot tube - D) Failure of the electrical system. **Correct: A)** > **Explanation:** The airspeed indicator, altimeter, and vertical speed indicator are all connected to the static pressure port. If the static pressure system is blocked (e.g., by ice, water, or a cover left on), all three instruments will give erroneous readings simultaneously. A blocked pitot tube (C) would affect only the airspeed indicator. A leaking compensating vessel (B) affects only the VSI. An electrical failure (D) does not affect these purely pneumatic instruments. ### Q22: When is it necessary to adjust the pressure in the reference scale of an alitimeter? ^q22 - A) After maintance has been finished - B) Every day before the first flight - C) Once a month before flight operation - D) Before every flight and during cross country flights **Correct: D)** > **Explanation:** The altimeter's reference pressure (subscale) must be set before every flight to the correct local QNH/QFE so that the altimeter reads the correct altitude or height. During cross-country flights, QNH changes as the pilot moves between pressure regions, so updates are required when crossing into new altimeter setting regions. Monthly (C) or only after maintenance (A) settings would result in significant altitude errors. ### Q23: The term "inclination" is defined as... ^q23 - A) Deviation induced by electrical fields. - B) Angle between magnetic and true north - C) Angle between earth's magnetic field lines and horizontal plane. - D) Angle between airplane's longitudinal axis and true north. **Correct: C)** > **Explanation:** Magnetic inclination (dip) is the angle between the Earth's magnetic field vector and the horizontal plane at any given location. It is 0° at the magnetic equator and 90° at the magnetic poles. Deviation (A) is the error caused by magnetic fields within the aircraft. Magnetic variation/declination (B) is the angle between magnetic and true north. Option D describes aircraft heading, which is unrelated. ### Q24: With decreasing air density the airflow speed increases at stall speed (TAS) and vice verca. How has a final approach to be conducted on a hot summer day? ^q24 - A) With increased speed indication (IAS) - B) With unchanged speed indication (IAS) - C) With decreased speed indication (IAS) - D) With additional speed according POH **Correct: B)** > **Explanation:** The airspeed indicator measures IAS (Indicated Airspeed), which is derived from dynamic pressure. At lower air density (hot day, high altitude), TAS is higher than IAS for the same dynamic pressure. The aerodynamic behaviour of the wing (lift, stall) depends on dynamic pressure (and thus IAS), not on TAS. Therefore stall occurs at the same IAS regardless of density. The approach should be flown at the same IAS as always (B). Adding speed (D) or reducing IAS (C) based on temperature alone is not correct for stall margin management with IAS. ### Q25: The load factor n describes the relationship between... ^q25 - A) Weight and thrust. - B) Drag and lift - C) Lift and weight - D) Thrust and drag. **Correct: C)** > **Explanation:** The load factor (n) is the ratio of the aerodynamic lift acting on the aircraft to the aircraft's weight: n = L/W. In level unaccelerated flight, n = 1. In turns or pull-ups, n increases. It does not describe weight/thrust (A), drag/lift (B), or thrust/drag (D) relationships. ### Q26: The term static pressure is defined as pressure... ^q26 - A) Inside the airplane cabin. - B) Of undisturbed airflow - C) Resulting from orderly flow of air particles. - D) Sensed by the pitot tube. **Correct: B)** > **Explanation:** Static pressure is the pressure of the undisturbed ambient airmass — the atmospheric pressure acting equally in all directions at a given altitude. It is sensed through flush static ports on the fuselage skin. It is not the cabin pressure (A), not related to orderly flow direction (C — that is dynamic pressure), and is not sensed by the pitot tube alone (D — the pitot senses total pressure). ### Q27: The term inclination is defined as... ^q27 - A) Deviation induced by electrical fields. - B) Angle between magnetic and true north - C) Angle between earth's magnetic field lines and horizontal plane. - D) Angle between airplane's longitudinal axis and true north. **Correct: C)** > **Explanation:** Magnetic inclination (dip) is the angle between the Earth's total magnetic field vector and the local horizontal plane. At the magnetic equator, field lines are horizontal (0° dip); at the poles, they are vertical (90° dip). Deviation (A) is caused by onboard magnetic interference. Variation/declination (B) is the angle between magnetic and geographic north. Option D describes aircraft heading relative to true north.