Brunei DCA CPL(A) Mass & Balance Exam cheat sheet

Basic empty mass (BEM) = empty aircraft + crew + unusable fuel + full oil + fixed equipment; excludes usable fuel and payload.

Dry operating mass (DOM) = BEM + operational items (crew, catering, potable water, toilet chemicals) but excludes usable fuel and traffic load.

Zero fuel mass (ZFM) = DOM + traffic load (passengers + baggage + cargo + mail); no usable fuel included.

Take-off mass (TOM) = ZFM + take-off fuel; landing mass (LM) = TOM − trip fuel.

Traffic load = TOM − DOM − usable fuel; used to cross-check load sheet totals.

Mass is measured in kg (SI); 1 lb = 0.4536 kg; 1 kg = 2.2046 lb.

Moment = mass × balance arm (kg·m or kg·in); used to compute CG position.

CG position = total moment ÷ total mass; expressed in metres or inches from the datum.

Operational empty mass includes crew and operational items but excludes usable fuel and payload; it is the basis for DOM.

MTOM (maximum take-off mass) is the maximum certified mass for starting the take-off run; limited by structure and performance.

MLM (maximum landing mass) is the maximum certified mass at touchdown; may be lower than MTOM; excess fuel must be burned off or jettisoned.

MZFM (maximum zero fuel mass) is the maximum mass without usable fuel; protects wing bending and fuselage structure.

MRW (maximum ramp mass) = MTOM + taxi fuel allowance; also called maximum taxi mass.

Regulated take-off mass (RTOM) = lowest of MTOM, performance-limited take-off mass, and field-length-limited mass.

Regulated landing mass (RLM) = lowest of MLM and performance-limited landing mass (approach/climb/brake energy).

MTOM ≥ MRW − taxi fuel; MLM ≤ MTOM; MZFM ≤ MTOM − minimum fuel.

Exceeding MZFM can overstress the wing root even if MTOM is respected; check both.

Structural limits are fixed; performance limits vary with temperature, pressure altitude, runway, and obstacles.

CG is the point where the aircraft mass is considered concentrated; expressed as %MAC or distance from datum.

%MAC = (CG distance from datum − LEMAC) ÷ MAC × 100; LEMAC is leading edge of mean aerodynamic chord.

Forward CG limit: ensures sufficient elevator authority for rotation and landing flare; also increases stall speed and cruise drag.

Aft CG limit: ensures static and dynamic stability; too far aft reduces stick force and can cause pitch-up.

CG moves forward when mass is added ahead of the CG; moves aft when mass is added behind the CG.

CG shift = (mass added × distance from original CG) ÷ new total mass.

CG envelope is a plot of mass versus CG position; all loading must remain inside the certified envelope.

Lateral CG (for asymmetric loads) must remain within lateral limits; fuel imbalance is a common cause of lateral shift.

Operating empty CG is the reference for adding crew, fuel, and payload; each addition changes total moment.

Datum is an arbitrary vertical reference plane from which all balance arms are measured; often at or near the nose.

Balance arm (station) is the horizontal distance from datum to the item's CG; positive aft of datum, negative forward.

Moment = mass × arm; sum moments and masses separately, then divide total moment by total mass to find CG.

When using a datum forward of the aircraft, all arms are positive; when datum is inside the aircraft, some arms may be negative.

To convert arm in inches to metres: multiply by 0.0254; to convert metres to inches: multiply by 39.37.

Index units are scaled moments (e.g., moment ÷ 1000) used to simplify load sheets; index = (mass × arm) ÷ constant.

If datum is changed, all arms must be recalculated relative to the new datum; moments change accordingly.

For a loaded aircraft: CG = Σ(mass × arm) ÷ Σmass; include BEM, crew, fuel, payload, and any ballast.

Ballast added to correct CG: required mass = (total mass × desired CG shift) ÷ (ballast arm − new CG).

Load sheet shows DOM, traffic load, fuel, TOM, LM, ZFM, and CG position; must be signed by the person in command or delegated load controller.

Trim sheet (or CG chart) is used to determine CG position from total mass and total moment/index; must fall within envelope.

Last-minute changes (LMC) must be recorded and signed; if exceeded, a new load sheet is required.

Standard passenger masses: 84 kg (adult male), 76 kg (female), 35 kg (child), 0 kg (infant); use actual masses if known.

Baggage standard mass: 13 kg per piece for domestic; check operator's manual for specific values.

Fuel density: jet fuel 0.78–0.80 kg/L; AVGAS 0.72 kg/L; use actual density from refueller if available.

Load sheet must be amended if fuel or load changes after signing; final figures must match actual aircraft loading.

Dry operating index (DOI) is the index of the DOM; added loads are converted to index and summed to find CG index.

Trim sheet check: plot ZFM and TOM against forward/aft limits; both must be inside the envelope.

Fuel is carried in wings and fuselage tanks; fuel burn changes CG as tank contents change; wing fuel burn generally moves CG aft initially.

Payload distribution: passengers and cargo must be distributed to keep CG within limits; use seat maps and cargo hold limits.

Cargo compartment floor limits: maximum load per compartment and per unit area must not be exceeded.

Heavy cargo should be placed near the aircraft CG to minimise trim drag and maintain handling.

Fuel jettison or burn-off may be required if landing mass exceeds MLM; calculate fuel to burn = LM − MLM.

Adding payload aft of CG moves CG aft; adding forward moves CG forward; magnitude depends on arm difference.

Zero fuel mass limit must be checked before adding fuel; fuel added after ZFM check does not affect ZFM but affects TOM and LM.

Asymmetric fuel or cargo causes lateral imbalance; cross-feed or redistribute to keep within lateral CG limits.

Density of cargo affects volume-limited versus mass-limited loading; check both hold volume and floor load limits.

Higher mass increases stall speed (Vs ∝ √mass), take-off and landing distances, and reduces climb gradient and acceleration.

Take-off distance increases approximately with the square of mass for a given configuration; field length limit may reduce RTOM.

Climb performance: excess thrust = thrust − drag; higher mass increases induced drag and reduces climb rate.

Forward CG increases elevator deflection required, increases trim drag, and reduces cruise speed and range.

Aft CG reduces trim drag and can increase range, but reduces static stability and may cause pitch-up at stall.

Landing distance increases with mass due to higher approach speed and greater kinetic energy; brake energy limit may reduce MLM.

CG affects rotation authority: forward CG requires more elevator force; aft CG requires less but may cause over-rotation.

Mass affects single-engine climb gradient; performance-limited mass may be below MTOM.

CG outside limits can cause loss of control; always verify CG within envelope before flight.

Before flight, the pilot-in-command must ensure mass and CG are within limits; load sheet and trim sheet are part of flight documentation.

Load sheet must be retained for a period specified by the operator (often 3 months) and made available to the authority on request.

Last-minute changes (LMC) must be recorded, signed, and if the change exceeds a defined threshold (e.g., 1% of MTOM or 0.5% MAC), a new load sheet is required.

Passenger and baggage mass standards must be used unless actual masses are obtained; operator's manual specifies values.

Fuel density must be determined from actual temperature or refueller's certificate; standard density may be used if not available.

The aircraft must not take off if mass exceeds MTOM or CG is outside limits; landing mass must not exceed MLM.

Documentation includes load sheet, trim sheet, fuel receipt, and any ballast or special load instructions.

Regulatory requirements: Brunei DCA ANR Part 121/135 or equivalent; operator's manual and MEL must be complied with.

Emergency situations: if landing mass exceeds MLM, a fuel jettison or holding to burn fuel may be required; follow AFM procedures.