tural analysis and testing of these structures, it will be permissible to assume that the critical load in each of these directions, as determined from the prescribed flight, ground, and emergency landing conditions, acts separately. If the applicant desires, selected combinations of loads may be used, provided the required strength in all specified directions is substantiated. (TSO C-25, Aircraft Seats and Berths, § 514.25 of this title, outlines acceptable methods for testing seats and berths).

[Supp. 22, 18 F. R. 5563, Sept. 17, 1953]

§ 4b.359 Cargo and baggage compart

ments.

(See also §§ 4b.382 to 4b.384.)

(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 § 4b.260.

(b) Provisions 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) Provisions shall be made to protect the passengers and crew from injury by the contents of any

com

partment, taking into account the emergency landing conditions of § 4b.260. (15 F. R. 3543, June 8, 1950, as amended by Amdt. 4b-6, 17 F. R. 1094, Feb. 5, 1952]

EMERGENCY PROVISIONS

§ 4b.360 General.

The requirements of §§ 4b.361 and 4b.362 shall apply to the emergency provisions.

§ 4b.361 Ditching.

Compliance with this section is optional. The requirements of this section are intended to safeguard the occupants in the event of an emergency landing during overwater flight. When compliance is shown with the provisions of paragraphs (a) through (c) of this section and with the provisions of §§ 4b.362(d), 4b.645, and 4b.646, the type certificate shall include certification to that effect. When an airplane is certificated to include ditching provisions, the recommended ditching procedures established on the basis of these requirements shall be set forth in the Airplane Flight Manual (see § 4b.742(d)).

(a) All practicable design measures compatible with the general characteristics of the type airplane shall be taken to minimize the chance of any behavior of the airplane in an emergency landing on water which would be likely to cause immediate injury to the occupants or to make it impossible for them to escape from the airplane. The probable behavior of the airplane in a water landing shall be investigated by model tests or by comparison with airplanes of similar configuration for which the ditching characteristics are known. In this investigation account shall be taken of scoops, flaps, projections, and all other factors likely to affect the hydrodynamic characteristics of the actual airplane.

(b) It shall be shown that under reasonably probable water conditions the flotation time and trim of the airplane will permit all occupants to leave the airplane and to occupy the life rafts required by § 4b.645. If compliance with this provision is shown by buoyancy and trim computations, appropriate allowances shall be made for probable structural damage and leakage.

NOTE: In the case of fuel tanks which are equipped with fuel Jettisoning provisions and which can be reasonably expected to withstand a ditching without leakage, the Jettisonable volume of fuel may be considered as buoyancy volume.

(c) External doors and windows shall be designed to withstand the probable maximum local pressures, unless the effects of the collapse of such parts are taken into account in the investigation of the probabie behavior of the airplane in a water landing as prescribed in paragraphs (a) and (b) of this section. [Amdt. 4b-8, 18 F. R. 2215, Apr. 18, 1953] § 4b.362 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 airplane being on fire. If the airplane is divided into separate compartments arranged so that the minimum unobstructed passageway between such compartments is not available as required by paragraph (g) of this section, requirements of this section shall be applied to each compartment independently. Passenger and crew entrances 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, one on each side of the airplane, or, alternatively, a top hatch shall be provided. Such exits shall be of sufficient size and shall be so located as to permit rapid evacuation by the crew. Such exits shall not be required in airplanes having a passenger capacity of 20 or less if the Administrator finds that the proximity of passenger emergency exits to the flight crew area offers a convenient and readily accessible means of evacuation for the flight crew.

(b) Passenger emergency exits; type and location. All required exits shall be in such specific locations as will afford the most effective means of passenger evacuation. The type of exits and their general location shall be as follows:

(1) Type I: A rectangular opening of not less than 24 inches wide by 48 inches high, with corner radii not greater than 3 the width of the exit. The first Type I exit on each side of the fuselage shall be located in the aft portion of the passenger compartment unless the configuration of the airplane is such that some other location would afford a more effective means of passenger evacuation. All Type I exits shall be floor level exits.

(2) Type II: A rectangular opening of not less than 20 inches wide by 44 inches high, with corner radii not greater than 3 the width of the exit. Unless Type I exits are required, one Type II exit on each side of the fuselage shall be located in the aft portion of the passenger compartment except where the configuration of the airplane is such that some other location would afford a more effective means of passenger evacuation. Type II exits shall be floor level exits unless located over the wing in which case they shall have a step-up inside the airplane of not more than 10 inches and a step-down outside the airplane of not more than 17 inches.

(3) Type III: A rectangular opening of not less than 20 inches wide by 36 inches high, with corner radii not greater than 3 the width of the exit, located over the wing with a step-up inside the airplane of not more than 20 inches and a step-down outside the airplane of not more than 27 inches.

(4) Type IV: A rectangular opening of not less than 19 inches wide by 26 inches high, with corner radii not greater than 1⁄2 the width of the exit, located over the wing with a step-up inside the airplane of not more than 29 inches and a stepdown outside the airplane of not more than 36 inches.

NOTE: Larger openings than those specified in paragraph (b) of this section shall be acceptable, whether or not of rectangular shape, provided that the specified rectangular openings can be inscribed therein, and provided further that the base of the inscribed rectangular opening meets the specifiled step-up and step-down heights.

(c) Passenger emergency exits; number required. Emergency exits of the type and location prescribed in paragraph (b) of this section shall be accessible to the passengers and shall be provided in accordance with subparagraphs (1) through (5) of this paragraph.

(1) The relation between the passenger seating capacity and the type and number of exits provided on each side of the airplane shall be as follows:

NOTE: Although similar exits and their locations are prescribed for each side of the fuselage, it is not the intent of this regulation to require that the exits necessarily be at locations diametrically opposite each other.

(2) Additional exits shall be provided on airplanes having 220 or more passengers. The additional exits shall provide an effective means of passenger evacuation consistent with the minima provided in the table in subparagraph (1) of this paragraph.

(3) In applying subparagraph (1) of this paragraph, it shall be acceptable to install 2 Type IV exits in lieu of each required Type III exit.

(4) If the Administrator finds that there exist compensating factors in the

emergency evacuation means provided, it shall be permissible to increase the passenger seating capacity beyond that shown in subparagraph (1) of this paragraph, except that such increase in seating capacity shall in no case exceed 10 passengers.

(5) On airplanes where the vertical location of the wing does not permit the installation of over-wing exits, an exit the dimensions of which are not less than those prescribed in paragraph (b) (3) of this section shall be installed for each Type III and each Type IV exit required by subparagraph (1) of this paragraph.

(d) Ditching emergency exits. Except as otherwise provided in this paragraph, at least 2 exits, one on each side of the airplane, meeting the minimum dimensions of the exits specified in paragraph (b) (3) of this section and located above the water level, shall be provided. On airplanes with a passenger seating capacity of 10 or less, the minimum dimensions of the exit specified in paragraph (b) (4) of this section shall be acceptable. In addition, it shall be shown that there is not less than one emergency exit located above the water level for every 35 passengers. It shall be permissible to substitute 2 type IV exits for each required type III exit. When the configuration of the airplane is such that it will not permit the location of side exits above the water level, the required number of side exits shall be replaced by an equal number of overhead hatches of not less than the dimensions of exits specified in paragraph (b) (3) of this section, except that on airplanes having a passenger capacity of 35 or less only one such overhead hatch need be provided.

(e) 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 except that the sliding window emergency exit in the flight crew area need not be openable from the outside if the Administrator finds that the proximity of other approved exits makes them convenient and readily accessible to the flight crew area.

(3) The means of opening emergency exits shall be simple and obvious and

shall not require exceptional effort of a person opening them.

(4) Means shall be provided for locking each emergency exit and for safeguarding against opening in flight either inadvertently by persons or as a result of mechanical failure.

(5) Means shall be provided for a direct visual inspection of the locking mechanism by crew members to ascertain whether all emergency exits for which the initial opening movement is outward are fully locked.

(6) Provision shall be made to minimize the possibility of jamming of emergency exits as a result of fuselage deformation in a minor crash landing.

(7) For all landplane emergency exits other than exits located over the wing which are more than 6 feet from the ground with the airplane on the ground and the landing gear extended, approved means shall be provided to assist the occupants in descending to the ground.

(8) The proper functioning of emergency exit installations shall be demonstrated by test.

(f) Emergency exit marking. (1) All passenger emergency exits, their means of access, and their means of opening shall be marked conspicuously. The identity and location of emergency exits shall be recognizable from a distance equal to the width of the cabin. The location of the emergency exit operating handle and the instructions for opening shall be marked on or adjacent to the emergency exit and shall be readable from a distance of 30 inches.

(2) A source or sources of light, with an energy supply independent of the main lighting system, shall be installed to illuminate all emergency passenger exit markings. Such lights shall be designed to function automatically in a crash landing and shall also be operable manually.

(3) All emergency exits which are required to be openable from the outside, and their means of opening shall be marked on the outside of the airplane for guidance of rescue personnel.

(g) Emergency exit access. Passageways between individual compartments of the passenger area and passageways leading to Type I and Type II emergency exits (see paragraph (b) of this section) shall be unobstructed and shall be not less than 20 inches wide. Adjacent to emergency exits where assisting

means are required by paragraph (e) (7) of this section, there shall be sufficient additional space to allow a crew member to assist in the evacuation of passengers without reduction in the unobstructed width of the passageway to such exit. Access shall be provided from the main aisle to all Type III and Type IV exits and such access shall not be obstructed by seats, berths, or other protrusions to an extent which would reduce the effectiveness of the exit, except that minor obstructions shall be permissible if the Administrator finds that compen-. sating factors are present to maintain the effectiveness of the exit. If it is necessary to pass through a doorway to reach any required emergency exit from any seat in the passenger cabin, the door shall be provided with a means to latch it in the open position. A suitable placard stating that the door is to be latched in the open position during takeoff and landing shall be installed.

(h) Width of main aisle. The main passenger aisle at any point between seats shall not be less than 15 inches wide up to a height above the floor of 25 inches and not less than 20 inches wide above that height. For airplanes having a maximum passenger seating capacity of 19 or less, these aisle widths shall not be less than 12 inches wide up to a height above the floor of 25 inches and not less than 20 inches above that height.

[Amdt. 4b 4, 16 F. R. 11761, Nov. 21, 1951, as amended by Amdt. 4b-1, 19 F. R. 2250, Apr. 20, 1954; Amdt. 4b-5, 22 F.R. 1546, Mar. 9, 1957; 22 F.R. 1931, Mar. 22, 1957; Amdt. 4b-6, 22 F.R. 5565, July 16, 1957; Amdt. 4b-8, 23 F.R. 2591, Apr. 19, 1958; Amdt. 4b-11, 24 F.R. 7070, Sept. 9, 1959]

§ 4b.362-1 Flight crew emergency exits (FAA policies which apply to § 4b.362(a)).

(a) A flight crew area emergency exit should be a minimum of 19" x 20" unobstructed rectangular opening; however, other size and shape minimums will also be acceptable providing a demonstration of exit utility, using typical flight crew personnel, is satisfactorily demonstrated to the Administrator.

(b) The provisions of § 4b.362 (e) (2) through (8) and (f) are also applicable to flight crew emergency exits When the internal exit "opening means" involve sequence operations, operation of two handles or latches, release of safety catches, etc., such means will be accept

The step-down distances specified in § 4b.362 (b) (2), (3), and (4) mean the actual distances between the bottom of the required openings and a useable foothold which extends out from the fuselage and is large enough to be effective without searching visually or by feel. [Supp. 37, 23 F. R. 2789, Apr. 26, 1958] § 4b.362-3 Number of passengers (FAA policies which apply to § 4b.362(c)). (a) Cabin attendants are considered part of the crew and are not included in the passenger seating capacity, § 4b.362 (c) (1).

(b) The following compensatory factor in emergency evacuation means will be acceptable for an increase in the passenger seating capacity beyond the limits specified in § 4b.362 (c) (1).

(1) The installation of an approved inflatable slide at each floor level exit, other than over the wing exits, is acceptable for:

(i) An increase of no more than 5 passengers on airplanes having at least 2 such exits; or

(ii) An increase of no more than 10 passengers on airplanes having at least 4 such exits.

[Supp. 37, 23 F. R. 2789, Apr. 26, 1958]

1

§ 4b.362-4 Emergency exit design descent means (FAA policies which apply to § 4b.362(e) (7)).

(a) The assist device required for crew exits may be a rope or any other device demonstrated to be suitable for the purpose. If a rope is provided, it should be attached to the fuselage structure at or above the upper limit of the exit opening. The rope and attachment should be capable of withstanding a 400 lb. static load.

1 Consideration should be given to such factors affecting the utility of Type III and Type IV exits as weight, ease of handling, provision of hand holds, stowage space, adequacy of instructions, etc. A side hinged or external opening exit would not be as critical from the weight standpoint as one removed inwardly which must be moved an appreciable distance to clear the exit approach.

(b) When required by § 4b.362 (e) (7) at floor level passenger exits, the approved means may be an inflatable slide, a non-inflatable slide, or any other device approved by FAA as suitable for the purpose. Ropes or ladders will not be approved as descent means for use at floor level passenger exits.

[Supp. 37, 23 F. R. 2789, Apr. 26, 1958] § 4b.362-5 Emergency exit marking (FAA policies which apply to § 4b.362 (f)).

(a) Exits in excess of the number required by the table in § 4b.362 (c) (1), need not be marked as emergency exits, but if so marked, such exits must meet all requirements of § 4b.362 for the particular type.

(b) Emergency exits used solely for emergency evacuation of the aircraft should be marked "Emergency Exit." Emergency exits customarily used in entering or leaving the airplane need only be marked with the word "Exit." In either case, the marking should be in red or in another color which provides adequate contrast where red might be ineffective against the cabin color scheme.

(c) Opening instructions when not on the exit should be immediately beside the exit and no special effort should be required by a person having 20/20 vision to read these instructions. Readability should be evaluated under representative day and emergency night lighting conditions.

[Supp. 37, 23 F. R. 2790, Apr. 26, 1958] § 4b.362-6 Emergency exit accesS (FAA policies which apply to § 4b.362 (g)).

(a) Attendant seating facilities' should not normally result in any reduction in required aisle widths, passageways between compartments, or the minimum 20'' passageway leading to Types I and II exits. Attendant seating facilities provided with any acceptable means of clearing the passageway immediately is not considered as being an obstruction to these passageways. An acceptable means of demonstrating compliance would be a spring loaded attendant seat which provides automatic retraction

Under such seating arrangements, particular attention should be directed to compliance with § 4b.260 (c) to protect the attendant from incapacitation by aircraft or galley equipment.

when the seat is vacated. Unless the seat is aft facing, the seat should also be equipped with a shoulder harness.

(b) When it is required that there be an area adjacent to an exit to permit a crew member to assist passengers in the use of escape devices, a 12" x 20" area with the long dimension parallel to and clear of the required 20'' exit approach passageway or equivalent facility should be provided. The area should be adequate to permit an attendant to stand erect and to perform needed assist services in the evacuation of passengers.

(c) Projection of the seat backs into the minimum required exit opening may be permitted only if the seat back can be pushed forward or aft to clear the opening with the seat occupied. The force required to push the seat back away from the opening should be as low as practicable and should not exceed a maximum of 35 pounds with the seat unoccupied. The action should not require operation of any mechanical release. A clear opening should permit the required minimum exit shape to be projected inward past the seat bottom and back cushion. Minor protrusion of the seat upholstery is acceptable if it does not interfere with exit removal and if it would be compressed without special effort by the person(s) using the exit.

(d) Arm rests, curtains, or other protuberances should not restrict the required minimum opening unless they are removed simultaneously with opening of the exit.

(e) Berth installations, whether or not made up, should not decrease the accessibility and utility of emergency exits. [Supp. 37, 23 F. R. 2790, Apr. 26, 1958] § 4b.362-7 Width of main aisle (FAA policies which apply to § 4b.362 (h)).

In determining compliance with aisle width requirements in an airplane so arranged that passengers face the aisle, the minimum aisle should be considered to begin at a point 12'' forward of the leading edge of each seat.

[Supp. 37, 23 F. R. 2790, Apr. 26, 1958] VENTILATION, HEATING, AND