100+ Free PPL Flight Performance & Planning Practice Questions

Explanation: Basic Empty Mass (BEM) is the mass of the aircraft including its structure, power plant, fixed equipment, unusable fuel, and maximum operating fluids (including full engine oil and hydraulic fluid). It excludes usable fuel, crew, passengers, and baggage.

Explanation: Useful Load is calculated as Maximum Take-Off Mass minus Basic Empty Mass: Useful Load = MTOM - BEM = 1,150 kg - 715 kg = 435 kg. Useful load comprises usable fuel, pilot, passengers, and baggage.

Explanation: Zero Fuel Mass (ZFM) is the total mass of the aircraft including its Basic Empty Mass plus all payload/traffic load (pilot, passengers, baggage), but excluding all usable fuel. Exceeding ZFM limits can cause excessive bending stress at the wing root.

Explanation: Step 1: Calculate total mass: 750 + 160 + 30 + 90 = 1,030 kg. Step 2: Calculate moments for each item: - BEM Moment = 1,575 kg·m - Front Seats = 160 kg × 2.5 m = 400 kg·m - Rear Seats = 30 kg × 3.2 m = 96 kg·m - Fuel = 90 kg × 2.3 m = 207 kg·m Total Moment = 1,575 + 400 + 96 + 207 = 2,278 kg·m. Step 3: Calculate CG: CG = Total Moment / Total Mass = 2,278 / 1,030 = 2.2116 m ≈ 2.21 m.

Explanation: Step 1: Calculate item moments / index values: - Front seats: 150 kg × 1.0 m = 150 kg·m → Index = 15.0 - Rear seats: 120 kg × 1.8 m = 216 kg·m → Index = 21.6 - Fuel: 100 kg × 1.2 m = 120 kg·m → Index = 12.0 Step 2: Total Mass = 800 + 150 + 120 + 100 = 1,170 kg. Step 3: Total Index = 40.0 + 15.0 + 21.6 + 12.0 = 88.6 (Total Moment = 886 kg·m). Step 4: CG = Total Moment / Total Mass = 886 / 1,170 = 0.757 m.

Explanation: A forward CG location increases the tailplane downforce required to maintain level flight. This increases effective wing loading, resulting in a higher stall speed, higher longitudinal stability, heavier stick forces, longer take-off distance, and increased trim drag (which lowers cruise speed).

Explanation: An aft CG reduces the moment arm of the horizontal stabilizer, decreasing longitudinal stability. Stick forces become dangerously light or reversed, pitch control becomes twitchy, and recovery from stalls or spins may be impossible because elevator control cannot force the nose down.

Explanation: Step 1: Calculate distance shifted: Distance = 3.5 m - 1.5 m = 2.0 m forward. Step 2: Apply CG shift formula: Shift = (Mass Shifted × Distance Shifted) / Total Mass = (20 kg × 2.0 m) / 1,000 kg = 40 / 1,000 = 0.04 m forward. Step 3: New CG = 2.10 m - 0.04 m = 2.06 m aft of datum.

Explanation: On most general aviation aircraft (e.g. Cessna 172, Piper PA-28), wing fuel tanks are intentionally positioned near the aircraft CG arm. Consequently, as fuel is consumed in flight, total weight decreases while the CG position remains relatively stable within limits.

Explanation: Operating Mass = BEM + Take-off Fuel = 730 + 90 = 820 kg. Max Allowable Payload = MTOM - Operating Mass = 1,150 - 820 = 330 kg. (Taxi fuel is burned on the ground prior to take-off, so it does not reduce take-off payload.)