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The main rotor blade pitch control mechanism shall be arranged to permit rapid entry into autorotative flight in the event of power failure.

§ 7.328 Power boost and power-operated control systems.

When a power boost or power-operated control system is used, an alternate system shall be immediately available, such that the rotorcraft can be flown and landed safely in the event of any single failure in the power portion of the sysItem or in the event of failure of all engines. Such alternate system may be a duplicate power portion or a manually operated mechanical system. The power portion shall include the power source (e.g., hydraulic pumps), and such items as valves, lines, and actuators. The failure of mechanical parts (such as piston rods and links), and the jamming of power cylinders need not be considered if failure or jamming is considered to be extremely remote.

[Amdt. 7-4, 24 F.R. 7076, Sept. 1, 1959]

LANDING GEAR

§ 7.330 General.

The requirements of §§ 7.331 through 7.338 shall apply to the complete landing gear.

§ 7.331 Shock absorbers.

(a) The shock absorbing elements for the main, nose, and rear wheel units shall be substantiated by the tests specified in § 7.332.

(b) The shock absorbing ability of the landing gear in taxying shall be demonstrated by taxying tests (see § 7.236). § 7.332 Shock absorption tests.

Drop tests shall be conducted in accordance with paragraphs (a) and (b) of this section to substantiate the landing limit inertia load factor (see § 7.230 (d)) and to demonstrate the reserve energy absorption capacity of the landing gear. The drop tests shall be conducted with the complete rotorcraft or on units consisting of wheel, tire, and shock absorber in their proper relation.

(a) Limit drop test. The drop height in the limit drop test shall be 13 inches measured from the lowest point of the landing gear to the ground. A lesser drop height shall be permissible if it results in a drop test contact velocity found

by the Administrator to be equal to the greatest probable sinking speed of the rotorcraft at ground contact in power-off landings likely to be made in normal operation of the rotorcraft. In no case shall the drop height be less than 8 inches. If rotor lift is considered (see § 7.230 (c)), it shall be introduced in the drop test by the use of appropriate energy absorbing devices or by the use of an effective mass. The attitude in which the landing gear unit is tested shall be such as to simulate the landing condition which is critical from the standpoint of energy to be absorbed by the particular unit.

NOTE: In lieu of more rational computations, the following may be employed when use is made of an effective mass:

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W=WA

M for main gear units (pounds), equal to the static reaction on the particular unit with the rotorcraft in the most critical attitude; a rational method may be used in computing the main gear static reaction, taking into consideration the distance between the direction of the main wheel reaction and the aircraft center of gravity.

W=WN for nose wheel units (pounds),
equal to the vertical component of
the ground reaction which would
exist at the nose wheel, assuming
the mass of the rotorcraft acting at
the center of gravity and exerting
a force of 1.0g downward and 0.25g
forward.

h specified free drop height (inches).
L= ratio of assumed rotor lift to the
rotorcraft weight.

d= deflection under impact of the tire
(at the approved inflation pressure)
plus the vertical component of the
axle travel relative to the drop
mass (inches).

(b) Reserve energy absorption drop test. The reserve energy absorption capacity shall be demonstrated by a drop test in which the drop height is equal to 1.5 times the drop height prescribed in paragraph (a) of this section, and the rotor lift is assumed to be not greater than 1.5 times the rotor lift used in the limit drop tests, except that the resultant inertia load factor need not exceed 1.5 times the limit inertia load factor determined in accordance with paragraph (a) of this section. In this test the landing gear shall not collapse.

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§ 7.334

Retracting mechanism.

(a) General. (1) The landing gear retracting mechanism, wheel well doors, and supporting structure shall be designed for the loads occurring in the flight maneuvering conditions when the gear is in the retracted position, and for the combination of friction, inertia, and air loads occurring during retraction and extension at any air speed up to the design maximum landing gear extended speed.

(2) The landing gear, the retracting mechanism, and the rotorcraft structure including wheel well doors shall be designed to withstand flight loads, including those in yawed flight, occurring with the landing gear in the extended position at any air speed up to the design maximum landing gear extended speed.

(b) Landing gear lock. A positive means shall be provided for the purpose of maintaining the landing gear in the extended position.

(c) Emergency operation. When other than manual power for the operation of the landing gear is employed, emergency means for extending the landing gear shall be provided, so that the landing gear can be extended in the event of any reasonably probable failure in the normal retraction system. When an emergency system is installed, it shall provide for the failure of any single source of hydraulic, electric, or equivalent energy supply.

(d) Operation test. Proper functioning of the landing gear retracting mechanism shall be demonstrated by operation tests.

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(a) Landing gear tires shall be of a proper fit on the rim of the wheel, and their approved rating shall be such that it is not exceeded under the following conditions:

(1) Rotorcraft weight equal to the maximum design weight.

(2) Load on each main wheel tire equal to the corresponding static ground reaction when considering the critical center of gravity position.

(3) Load on nose wheel tires (to be compared with the dynamic rating established for such tires) equal to the reaction obtained at the nose wheel assuming the mass of the rotorcraft concentrated at the most critical center of gravity and exerting a force of 1.0g downward and 0.25g forward, the reactions being distributed to the nose and main wheels by the principles of statics with the drag reaction at the ground ap

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Floats shall be designed for the conditions set forth in paragraphs (a) and (b) of this section:

(a) Bag type floats. Bag type floats shall withstand the maximum pressure differential which might be developed at the maximum altitude for which certification with floats is sought. In addition, the floats shall withstand the vertical loads prescribed by § 7.245 (a) distributed along the length of the bag over three-quarters of the projected bag area.

(b) Rigid floats. Rigid type floats shall withstand the vertical, horizontal, and side loads prescribed in § 7.245. An appropriate load distribution under critical conditions shall be used. PERSONNEL AND CARGO ACCOMMODATIONS § 7.350 Pilot compartment; general.

(a) The arrangement of the pilot compartment and its appurtenances shall provide safety and assurance that the pilot will be able to perform all of his duties and operate the controls in the correct manner without unreasonable concentration and fatigue.

(b) When provision is made for a second pilot, the rotorcraft shall be controllable with equal safety from both seats.

(c) The pilot compartment shall be constructed to prevent leakage likely to be distracting to the crew or harmful to the structure when flying in rain or snow.

(d) Vibration and noise characteristics of cockpit appurtenances shall not interfere with the safe operation of the rotorcraft.

(e) A passageway between the pilot compartment and the passenger compartment shall be provided. Suitable means shall be provided to prevent passengers from entering the pilot compartment without permission.

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(1)

(a) Nonprecipitation conditions. The pilot compartment shall be arranged to afford the pilot(s) a sufficiently extensive, clear, and undistorted view for the safe operation of the rotorcraft.

(2) It shall be demonstrated during the day and, where appropriate, during the night by flight tests that the pilot compartment is free of glare and reflection which would tend to interfere with the pilots' vision.

(b) Precipitation conditions. (1) Means shall be provided so that the pilot(s) is afforded a sufficiently extensive view to permit safe operation under the following conditions:

(i) In heavy rain at forward speeds up to VH and

(ii) In the most severe icing condition in which operation of the rotorcraft is approved.

(2) In addition to the means provided in subparagraph (1) of this paragraph, the pilot shall be provided with a window which is openable under the conditions prescribed in subparagraph (1) of this paragraph and which provides the view prescribed in that subparagraph.

§ 7.352 Pilot windshield and windows. All glass panes shall be of a nonsplintering safety type.

§ 7.353 Controls.

(a) All cockpit controls shall be located to provide convenience in operation and in a manner tending to prevent confusion and inadvertent operation. (See also § 7.737.)

(b) The controls shall be so located and arranged with respect to the pilots' seats that there exists full and unrestricted movement of each control without interference from either the cockpit structure or the pilots' clothing when seated. This shall be demonstrated for individuals ranging from 5' 2" to 6' 0'' in height.

§ 7.354 Doors.

(a) Closed cabins shall be provided with at least one adequate and easily accessible external door.

(b) No passenger door shall be so located with respect to the rotor discs as to endanger persons using the door when appropriate operating instructions are employed.

(c) Means shall be provided for locking crew and external passenger doors and for safeguarding against their opening in flight either inadvertently by persons or as a result of mechanical failure. It shall be possible to open external doors from either the inside or the outside of the cabin while the rotorcraft is on the ground. The means of opening shall be simple and obvious and shall be so arranged and marked that it can be readily located and operated.

(d) Reasonable provisions shall be made to prevent the jamming of any external door as a result of fuselage deformation in a minor crash.

(e) Means shall be provided for a direct visual inspection of the locking mechanism by crew members to ascertain whether all external doors, including passenger, crew, service, and cargo doors are fully locked. In addition, visual means shall be provided to signal to appropriate crew members that all normally used external doors are closed and in the fully locked position.

(f) For outwardly opening external doors usable by persons for entrance or egress, an auxiliary safety latching device shall be provided which will prevent the door from coming open in the event of difficulties with the primary latching mechanism. If the door will not meet the requirements of paragraph (c) of this section with the auxiliary safety latching device in place, then suitable operating procedures shall be established to insure that the device shall not be in place during take-off or landing.

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landing, the seats, belts, harnesses (if used) and adjacent parts of the rotorcraft shall be such that a person making proper use of these facilities will not suffer serious injury in the emergency landing conditions as a result of inertia forces specified in § 7.260. Seats shall be of an approved type (see also § 7.643 concerning safety belts).

(b) Arrangement. (1) Passengers and crew shall be afforded protection from head injuries by one of the following

means:

(i) Safety belt and shoulder harness which will prevent the head from contacting any injurious object;

(ii) Safety belt and the elimination of all injurious objects within striking radius of the head; or

(iii) Safety belt and a cushioned rest which will support the arms, shoulders, head, and spine.

(2) For arrangements which do not provide a firm handhold on seat backs, hand grips or rails shall be provided along aisles to enable passengers or crew members to steady themselves while using the aisles in moderately rough air.

(3) All projecting objects which would cause injury to persons seated or moving about the rotorcraft in normal flight shall be padded.

(c) Strength. All seats and their supporting structure shall be designed for an occupant weight of 170 pounds with due account taken of the maximum load factors, inertia forces, and reactions be- | tween occupant, seat, and safety belt or harness corresponding with all relevant flight and ground load conditions, including the emergency landing conditions prescribed in § 7.260. In addition, the following shall apply:

(1) Pilot seats shall be designed for the reactions resulting from the application of pilot forces to the flight controls as prescribed in § 7.225.

(2) In determining the strength of the seat attachments to the structure and the safety belt or shoulder harness (if installed) attachments to the seat or structure, the inertia forces specified in § 7.260 (a) shall be multiplied by a factor of 1.33.

§ 7.356 Cargo and baggage compart

ments.

(See also § 7.382.)

(a) Each cargo and baggage compartment shall be designed for the placarded

maximum weight of contents and the critical load distributions at the appropriate maximum load factors corresponding with all specified flight and ground load conditions, excluding the emergency landing conditions of § 7.260.

(b) Provision shall be made to prevent the contents in the compartments from becoming a hazard by shifting under the loads specified in paragraph (a) of this section.

(c) Provision shall be made to protect the passengers and crew from injury by the contents of any compartment when the ultimate inertia force acting forward is 4g.

§ 7.357 Emergency evacuation.

Crew and passenger areas shall be provided with emergency evacuation means to permit rapid egress in the event of crash landings, whether with the landing gear extended or retracted, taking into account the possibility of the rotorcraft being on fire. Passenger entrance, crew, and service doors shall be considered as emergency exits if they meet the applicable requirements of this section.

(a) Flight crew emergency exits. Flight crew emergency exits shall be located in the flight crew area on both sides of the rotorcraft or as a top hatch to provide for rapid evacuation. Such exits shall not be required on small rotorcraft where the Administrator finds that the proximity of passenger emergency exits to the flight crew area renders them convenient and readily accessible to the flight crew.

(b) Passenger emergency exits; type and location. The types of exits and their location shall be as follows:

(1) Type 1. A rectangular opening of not less than 24 inches wide by 48 inches high, with corner radii not greater than 4 inches, located in the passenger area in the side of the fuselage at floor level and as far away as practicable from areas which might become potential fire hazards after a crash.

(2) Type II. Same as Type I (subparagraph (1) of this paragraph) except that the opening is not less than 20 inches wide by 44 inches high.

(3) Type III. A rectangular opening of not less than 20 inches wide by 36 inches high, with corner radii not greater than 4 inches, located in the passenger area in the side of the fuselage and as far away as practicable from areas which

might become potential fire hazards after a crash.

(4) Type IV. A rectangular opening of not less than 19 inches wide by 26 inches high, with corner radii not greater than 4 inches, located in the side of the fuselage with a step-up inside the rotorcraft of not more than 29 inches.

NOTE: Larger openings than those specified in paragraph (b) of this section will be acceptable, whether or not of rectangular shape, provided the specified rectangular openings can be inscribed therein, and further provided that the base of the opening affords a flat surface not less than the width specified.

(c) Passenger emergency exits; number required. Emergency exits of the type and located as prescribed in paragraph (b) of this section shall be accessible to the passengers, and shall be provided in accordance with the following table:

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In addition to the number of exits required for the side of the fuselage, openings shall be provided in other parts of the fuselage (top, bottom, or ends) so that, in the event of a crash landing in which the fuselage comes to rest on its side, emergency exits shall be available for egress. When it can be satisfactorily demonstrated that the configuration of the rotorcraft is such that the probability of the rotorcraft rolling over and coming to rest on the side of the fuselage after a crash landing is extremely remote, it shall be acceptable to provide emergency exits in the side of the fuselage only.

(d) Emergency exit arrangement. (1) Emergency exits shall consist of movable doors or hatches in the external walls of the fuselage and shall provide an unobstructed opening to the outside.

(2) All emergency exits shall be openable from the inside and from the outside.

(3) The means of opening emergency exits shall be simple and obvious and shall not require exceptional effort of a person opening them.

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