EASA ATPL — Mass & Balance (031) Exam Prep

Correct answer: B. 23.25 m

CG position from datum = MAC leading edge + (CG % MAC × MAC length) = 22.0 + (0.25 × 5.0) = 22.0 + 1.25 = 23.25 m. The percentage MAC is converted to a distance along the MAC and added to the leading edge station to give the absolute CG position from the aircraft datum.

Correct answer: D. Both MZFM and MLM must be checked; MZFM is the limiting factor at 57,000 kg

Traffic load must satisfy all mass limits. MZFM limit: max traffic load = 57,000 - 58,000 = negative, which means the operating mass already exceeds MZFM! However, re-reading: DOM vs operating mass — if operating mass is 58,000 kg (DOM + crew), then ZFM = operating mass + traffic load must not exceed 57,000. This is already exceeded. In practice, this means the operating mass figure must be checked. Assuming DOM is 56,000 and operating mass includes some payload: MZFM allows only 57,000 - 56,000 = 1,000 kg from MZFM perspective. Both limits must always be checked; MZFM is often the most restrictive.

Correct answer: A. ΔCG = (mass of item × distance moved) / total aircraft mass

The change in CG position when an item is moved within the aircraft is: ΔCG = (mass of item × distance moved) / total aircraft mass. This is derived from the moment equation: the change in total moment equals the mass moved multiplied by the distance moved, and the CG shift equals the change in moment divided by the total mass.

Correct answer: A. It ensures sufficient elevator authority to rotate and flare the aircraft

The forward CG limit is determined primarily by the elevator/stabiliser authority required to rotate the aircraft at VR during take-off and to flare for landing. A CG too far forward increases the nose-down pitching moment, which may exceed the available elevator-up deflection to achieve the required pitch attitude. It also increases trim drag and stall speed.

Correct answer: C. 88 kg

Under EU-OPS (now Part-CAT/Part-NCC), the standard passenger mass for adult males including hand baggage is 88 kg (for aircraft with 20 or more passenger seats). For females, the standard mass is 70 kg. For aircraft with 30+ seats where the proportion of male/female is unknown, an 'all adult' figure of 84 kg may be used. Children (2–12 years) are 35 kg.

Correct answer: C. The CG movement depends on the relationship between the fuel tank CG and the aircraft CG

The direction of CG movement depends on whether the fuel being jettisoned is ahead of or behind the current aircraft CG. If the wing tank CG is behind the aircraft CG (common in swept-wing aircraft), jettisoning fuel will move the CG forward. If the tank CG is ahead of the aircraft CG, the CG moves aft. In most swept-wing jets, wing fuel is aft of the CG, so jettisoning moves CG forward.