Commission Regulation (EC) No 8/2008Show full title

“Appendix 1 to OPS 1.605 Mass and Balance — General(See OPS 1.605)

(a)

Determination of the dry operating mass of an aeroplane

(1)

Weighing of an aeroplane

(i)

New aeroplanes are normally weighed at the factory and are eligible to be placed into operation without reweighing if the mass and balance records have been adjusted for alterations or modifications to the aeroplane. Aeroplanes transferred from one operator with an approved mass control programme to another operator with an approved programme need not be weighed prior to use by the receiving operator unless more than 4 years have elapsed since the last weighing.

(ii)

The individual mass and centre of gravity (CG) position of each aeroplane shall be re-established periodically. The maximum interval between two weighings must be defined by the operator and must meet the requirements of OPS 1.605 (b). In addition, the mass and the CG of each aeroplane shall be re-established either by:

(A)

Weighing; or

(B)

Calculation, if the operator is able to provide the necessary justification to prove the validity of the method of calculation chosen, whenever the cumulative changes to the dry operating mass exceed ±0,5 % of the maximum landing mass or the cumulative change in CG position exceeds 0,5 % of the mean aerodynamic chord.

(2)

Fleet mass and CG position

(i)

For a fleet or group of aeroplanes of the same model and configuration, an average dry operating mass and CG position may be used as the fleet mass and CG position, provided that the dry operating masses and CG positions of the individual aeroplanes meet the tolerances specified in subparagraph (ii) below. Furthermore, the criteria specified in subparagraphs (iii), (iv) and (a)(3) below are applicable.

(ii)

Tolerances

(A)

If the dry operating mass of any aeroplane weighed, or the calculated dry operating mass of any aeroplane of a fleet, varies by more than ±0,5 % of the maximum structural landing mass from the established dry operating fleet mass or the CG position varies by more than ±0,5 % of the mean aero-dynamic chord from the fleet CG, that aeroplane shall be omitted from that fleet. Separate fleets may be established, each with differing fleet mean masses.

(B)

In cases where the aeroplane mass is within the dry operating fleet mass tolerance but its CG position falls outsides the permitted fleet tolerance, the aeroplane may still be operated under the applicable dry operating fleet mass but with an individual CG position.

(C)

If an individual aeroplane has, when compared with other aeroplanes of the fleet, a physical, accurately accountable difference (e.g. galley or seat configuration), that causes exceedance of the fleet tolerances, this aeroplane may be maintained in the fleet provided that appropriate corrections are applied to the mass and/or CG position for that aeroplane.

(D)

Aeroplanes for which no mean aerodynamic chord has been published must be operated with their individual mass and CG position values or must be subjected to a special study and approval.

(iii)

Use of fleet values

(A)

After the weighing of an aeroplane, or if any change occurs in the aeroplane equipment or configuration, the operator must verify that this aeroplane falls within the tolerances specified in subparagraph (2)(ii) above.

(B)

Aeroplanes which have not been weighed since the last fleet mass evaluation can still be kept in a fleet operated with fleet values, provided that the individual values are revised by computation and stay within the tolerances defined in subparagraph (2)(ii) above. If these individual values no longer fall within the permitted tolerances, the operator must either determine new fleet values fulfilling the conditions of subparagraphs (2)(i) and (2)(ii) above, or operate the aeroplanes not falling within the limits with their individual values.

(C)

To add an aeroplane to a fleet operated with fleet values, the operator must verify by weighing or computation that its actual values fall within the tolerances specified in subparagraph (2)(ii) above.

(iv)

To comply with subparagraph (2)(i) above, the fleet values must be updated at least at the end of each fleet mass evaluation.

(3)

Number of aeroplanes to be weighed to obtain fleet values

(i)

If ‘n’ is the number of aeroplanes in the fleet using fleet values, the operator must at least weigh, in the period between two fleet mass evaluations, a certain number of aeroplanes defined in the Table below:

Number of aeroplanes in the fleet	Minimum number of weighings
2 or 3	N
4 to 9	(n + 3)/2
10 or more	(n + 51)/10

(ii)

In choosing the aeroplanes to be weighed, aeroplanes in the fleet which have not been weighed for the longest time should be selected.

(iii)

The interval between 2 fleet mass evaluations must not exceed 48 months.

(4)

Weighing procedure

(i)

The weighing must be accomplished either by the manufacturer or by an approved maintenance organisation.

(ii)

Normal precautions must be taken consistent with good practices such as:

(A)

Checking for completeness of the aeroplane and equipment;

(B)

Determining that fluids are properly accounted for;

(C)

Ensuring that the aeroplane is clean; and

(D)

Ensuring that weighing is accomplished in an enclosed building.

(iii)

Any equipment used for weighing must be properly calibrated, zeroed, and used in accordance with the manufacturer's instructions. Each scale must be calibrated either by the manufacturer, by a civil department of weights and measures or by an appropriately authorised organisation within 2 years or within a time period defined by the manufacturer of the weighing equipment, whichever is less. The equipment must enable the mass of the aeroplane to be established accurately.

(b)

Special standard masses for the traffic load. In addition to standard masses for passengers and checked baggage, an operator can submit for approval to the Authority standard masses for other load items.

(c)

Aeroplane loading

(1)

An operator must ensure that the loading of its aeroplanes is performed under the supervision of qualified personnel.

(2)

An operator must ensure that the loading of the freight is consistent with the data used for the calculation of the aeroplane mass and balance.

(3)

An operator must comply with additional structural limits such as the floor strength limitations, the maximum load per running metre, the maximum mass per cargo compartment, and/or the maximum seating limits.

(d)

Centre of gravity limits

(1)

Operational CG envelope. Unless seat allocation is applied and the effects of the number of passengers per seat row, of cargo in individual cargo compartments and of fuel in individual tanks is accounted for accurately in the balance calculation, operational margins must be applied to the certificated centre of gravity envelope. In determining the CG margins, possible deviations from the assumed load distribution must be considered. If free seating is applied, the operator must introduce procedures to ensure corrective action by flight or cabin crew if extreme longitudinal seat selection occurs. The CG margins and associated operational procedures, including assumptions with regard to passenger seating, must be acceptable to the Authority.

(2)

In-flight centre of gravity. Further to subparagraph (d)(1) above, the operator must show that the procedures fully account for the extreme variation in CG travel during flight caused by passenger/crew movement and fuel consumption/transfer.