ED Decision 2003/15/RM
Each requirement of this Subpart must be met at each appropriate combination of weight and centre of gravity within the range of loading conditions for which certification is requested. This must be shown:
(a) By tests upon a rotorcraft of the type for which certification is requested or by calculations based on, and equal in accuracy to, the results of testing; and
(b) By systematic investigation of each required combination of weight and centre of gravity if compliance cannot be reasonably inferred from combinations investigated.
ED Decision 2007/013/R
(a) Maximum weight. The maximum weight, the highest weight at which compliance with each applicable requirement of this CS-27 is shown, must be established so that it is:
(1) Not more than:
(i) The highest weight selected by the applicant;
(ii) The design maximum weight, the highest weight at which compliance with each applicable structural loading condition of this CS-27 is shown; or
(iii) The highest weight at which compliance with each applicable flight requirement of this CS-27 is shown; or
(iv) The highest weight, as a function of altitude and temperature, in which the provisions of CS 27.79 and/or CS 27.143(c)(1) are demonstrated if the operating conditions (altitude and temperature) prescribed by those requirements can not be met; and
(2) Not less than the sum of:
(i) The empty weight determined under CS 27.29;
(ii) The weight of usable fuel appropriate to the intended operation with full payload;
(iii) The weight of full oil capacity; and
(iv) For each seat, an occupant weight of 77 kg (170 lbs) or any lower weight for which certification is requested.
(b) Minimum weight. The minimum weight, the lowest weight at which compliance with each applicable requirement of this CS-27 is shown, must be established so that it is:
(1) Not more than the sum of:
(i) The empty weight determined under CS 27.29; and
(ii) The weight of the minimum crew necessary to operate the rotorcraft, assuming for each crew member a weight no more than 77 kg (170 lbs), or any lower weight selected by the applicant or included in the loading instructions; and
(2) Not less than:
(i) The lowest weight selected by the applicant;
(ii) The design minimum weight, the lowest weight at which compliance with each applicable structural loading condition of this CS-27 is shown; or
(iii) The lowest weight at which compliance with each applicable flight requirement of this CS-27 is shown.
(c) Total weight with jettisonable external load. A total weight for the rotorcraft with a jettisonable external load attached that is greater than the maximum weight established under sub-paragraph (a) may be established for any rotorcraft-load combination if
(1) The rotorcraft-load combination does not include human external cargo,
(2) Structural component approval for external load operations under either CS 27.865, or under equivalent operational standards is obtained,
(3) The portion of the total weight that is greater than the maximum weight established under sub-paragraph (a) is made up only of the weight of all or part of the jettisonable external load,
(4) Structural components of the rotorcraft are shown to comply with the applicable structural requirements of this CS-27 under the increased loads and stresses caused by the weight increase over that established under sub-paragraph (a), and
(5) Operation of the rotorcraft at a total weight greater than the maximum certificated weight established under sub-paragraph (a) is limited by appropriate operating limitations under CS 27.865(a) and (d).
[Amdt. No.: 27/1]
CS 27.27 Centre of gravity limits
ED Decision 2003/15/RM
The extreme forward and aft centres of gravity and, where critical, the extreme lateral centres of gravity must be established for each weight established under CS 27.25. Such an extreme may not lie beyond:
(a) The extremes selected by the applicant;
(b) The extremes within which the structure is proven; or
(c) The extremes within which compliance with the applicable flight requirements is shown.
CS 27.29 Empty weight and corresponding centre of gravity
ED Decision 2003/15/RM
(a) The empty weight and corresponding centre of gravity must be determined by weighing the rotorcraft without the crew and payload but with:
(1) Fixed ballast;
(2) Unusable fuel; and
(3) Full operating fluids, including:
(i) Oil;
(ii) Hydraulic fluid; and
(iii) Other fluids required for normal operation of rotorcraft systems, except water intended for injection in the engines.
(b) The condition of the rotorcraft at the time of determining empty weight must be one that is well defined and can be easily repeated, particularly with respect to the weights of fuel, oil, coolant, and installed equipment.
ED Decision 2003/15/RM
Removable ballast may be used in showing compliance with the flight requirements of this Subpart.
CS 27.33 Main rotor speed and pitch limits
ED Decision 2003/15/RM
(a) Main rotor speed limits. A range of main rotor speeds must be established that:
(1) With power-on, provides adequate margin to accommodate the variations in rotor speed occurring in any appropriate manoeuvre, and is consistent with the kind of governor or synchroniser used; and
(2) With power-off, allows each appropriate autorotative manoeuvre to be performed throughout the ranges of airspeed and weight for which certification is requested.
(b) Normal main rotor high pitch limits (power-on). For rotorcraft, except helicopters required to have a main rotor low speed warning under sub-paragraph (e). It must be shown, with power-on and without exceeding approved engine maximum limitations, that main rotor speeds substantially less than the minimum approved main rotor speed will not occur under any sustained flight condition. This must be met by:
(1) Appropriate setting of the main rotor high pitch stop;
(2) Inherent rotorcraft characteristics that make unsafe low main rotor speeds unlikely; or
(3) Adequate means to warn the pilot of unsafe main rotor speeds.
(c) Normal main rotor low pitch limits (power-off). It must be shown, with power-off, that:
(1) The normal main rotor low pitch limit provides sufficient rotor speed, in any autorotative condition, under the most critical combinations of weight and airspeed; and
(2) It is possible to prevent overspeeding of the rotor without exceptional piloting skill.
(d) Emergency high pitch. If the main rotor high pitch stop is set to meet sub-paragraph (b)(1), and if that stop cannot be exceeded inadvertently, additional pitch may be made available for emergency use.
(e) Main rotor low speed warning for helicopters. For each single engine helicopter, and each multi-engine helicopter that does not have an approved device that automatically increases power on the operating engines when one engine fails, there must be a main rotor low speed warning which meets the following requirements:
(1) The warning must be furnished to the pilot in all flight conditions, including power-on and power-off flight, when the speed of a main rotor approaches a value that can jeopardise safe flight.
(2) The warning may be furnished either through the inherent aerodynamic qualities of the helicopter or by a device.
(3) The warning must be clear and distinct under all conditions, and must be clearly distinguishable from all other warnings. A visual device that requires the attention of the crew within the cockpit is not acceptable by itself.
(4) If a warning device is used, the device must automatically de-activate and reset when the low-speed condition is corrected. If the device has an audible warning, it must also be equipped with a means for the pilot to manually silence the audible warning before the low-speed condition is corrected.