Re: Question: Aircraft Door Type Designations

Date:         25 Mar 97 03:38:10 
From:         "Leo Kok" <t43583@dax.dehavilland.ca>
References:   1 2
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easy answer... as per FAR25.807 Amdt 83
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  Sec. 25.807   Emergency exits.

    (a) Type. For the purpose of this part, the types of exits are defined as
  follows:
    (1) Type I. This type is a floor level exit with a rectangular opening of
  not less than 24 inches wide by 48 inches high, with corner radii not greater
  than one-third the width of the exit.
    (2) Type II. This type is a rectangular opening of not less than 20 inches
  wide by 44 inches high, with corner radii not greater than one-third the
  width of the exit. Type II exits must be floor level exits unless located
  over the wing, in which case they may not have a step-up inside the airplane
  of more than 10 inches nor a step-down outside the airplane of more than 17
  inches.
    (3) Type III. This type is a rectangular opening of not less than 20 inches
  wide by 36 inches high, with corner radii not greater than one-third the
  width of the exit, and with a step-up inside the airplane of not more than 20
  inches. If the exit is located over the wing, the step-down outside the
  airplane may not exceed 27 inches.
    (4) Type IV. This type is a rectangular opening of not less than 19 inches
  wide by 26 inches high, with corner radii not greater than one-third the
  width of the exit, located over the wing, with a step-up inside the airplane
  of not more than 29 inches and a step-down outside the airplane of not more
  than 36 inches.
    (5) Ventral. This type is an exit from the passenger compartment through
  the pressure shell and the bottom fuselage skin. The dimensions and physical
  configuration of this type of exit must allow at least the same rate of
  egress as a Type I exit with the airplane in the normal ground attitude, with
  landing gear extended.
    (6) Tail cone. This type is an aft exit from the passenger compartment
  through the pressure shell and through an openable cone of the fuselage aft
  of the pressure shell. The means of opening the tailcone must be simple and
  obvious and must employ a single operation.
    (7) Type A. This type is a floor level exit with a rectangular opening of
  not less than 42 inches wide by 72 inches high with corner radii not greater
  than one-sixth of the width of the exit.
    (b) Step down distance. Step down distance, as used in this section, means
  the actual distance between the bottom of the required opening and a usable
  foot hold, extending out from the fuselage, that is large enough to be
  effective without searching by sight or feel.
    (c) Over-sized exits. Openings larger than those specified in this section,
  whether or not of rectangular shape, may be used if the specified rectangular
  opening can be inscribed within the opening and the base of the inscribed
  rectangular opening meets the specified step-up and step-down heights.
    (d) Passenger emergency exits. Except as provided in paragraphs (d) (3)
  through (7) of this section, the minimum number and type of passenger
  emergency exits is as follows:
    (1) For passenger seating configurations of 1 through 299 seats:

                                       Emergency exits for
                                         each side of the
                                             fuselage

                        Passenger
                         seating
                      configuration
                       (crewmember
                        seats not     Type  Type  Type  Type
                        included)      I     II   III    IV

                     1 through 9                           1
                     10 through 19                   1
                     20 through 39             1     1
                     40 through 79       1           1
                     80 through 109      1           2
                     110 through 139     2           1
                     140 through 179     2           2

    Additional exits are required for passenger seating configurations greater
  than 179 seats in accordance with the following table:

                            Additional
                            emergency    Increase in
                              exits       passenger
                            (each side     seating
                                of      configuration
                            fuselage)      allowed

                            Type A                110
                            Type I                 45
                            Type II                40
                            Type III               35

    (2) For passenger seating configurations greater than 299 seats, each
  emergency exit in the side of the fuselage must be either a Type A or Type I.
  A passenger seating configuration of 110 seats is allowed for each pair of
  Type A exits and a passenger seating configuration of 45 seats is allowed for
  each pair of Type I exits.
    (3) If a passenger ventral or tail cone exit is installed and that exit
  provides at least the same rate of egress as a Type III exit with the
  airplane in the most adverse exit opening condition that would result from
  the collapse of one or more legs of the landing gear, an increase in the
  passenger seating configuration beyond the limits specified in paragraph (d)
  (1) or (2) of this section may be allowed as follows:
    (i) For a ventral exit, 12 additional passenger seats.
    (ii) For a tail cone exit incorporating a floor level opening of not less
  than 20 inches wide by 60 inches high, with corner radii not greater than
  one-third the width of the exit, in the pressure shell and incorporating an
  approved assist means in accordance with Sec. 25.809(h), 25 additional
  passenger seats.
    (iii) For a tail cone exit incorporating an opening in the pressure shell
  which is at least equivalent to a Type III emergency exit with respect to
  dimensions, step-up and step-down distance, and with the top of the opening
  not less than 56 inches from the passenger compartment floor, 15 additional
  passenger seats.
    (4) For airplanes on which the vertical location of the wing does not allow
  the installation of overwing exits, an exit of at least the dimensions of a
  Type III exit must be installed instead of each Type IV exit required by
  subparagraph (1) of this paragraph.
    (5) An alternate emergency exit configuration may be approved in lieu of
  that specified in paragraph (d) (1) or (2) of this section provided the
  overall evacuation capability is shown to be equal to or greater than that of
  the specified emergency exit configuration.
    (6) The following must also meet the applicable emergency exit requirements
  of Secs. 25.809 through 25.813:
    (i) Each emergency exit in the passenger compartment in excess of the
  minimum number of required emergency exits.
    (ii) Any other floor level door or exit that is accessible from the
  passenger compartment and is as large or larger than a Type II exit, but less
  than 46 inches wide.
    (iii) Any other passenger ventral or tail cone exit.
    (7) For an airplane that is required to have more than one passenger
  emergency exit for each side of the fuselage, no passenger emergency exit
  shall be more than 60 feet from any adjacent passenger emergency exit on the
  same side of the same deck of the fuselage, as measured parallel to the
  airplane's longitudinal axis between the nearest exit edges.
    (e) Ditching emergency exits for passengers. Ditching emergency exits must
  be provided in accordance with the following requirements whether or not
  certification with ditching provisions is requested:
    (1) For airplanes that have a passenger seating configuration of nine seats
  or less, excluding pilots seats, one exit above the waterline in each side of
  the airplane, meeting at least the dimensions of a Type IV exit.
    (2) For airplanes that have a passenger seating configuration of 10 seats
  or more, excluding pilots seats, one exit above the waterline in a side of
  the airplane, meeting at least the dimensions of a Type III exit for each
  unit (or part of a unit) of 35 passenger seats, but no less than two such
  exits in the passenger cabin, with one on each side of the airplane. The
  passenger seat/exit ratio may be increased through the use of larger exits,
  or other means, provided it is shown that the evacuation capability during
  ditching has been improved accordingly.
    (3) If it is impractical to locate side exits above the waterline, the side
  exits must be replaced by an equal number of readily accessible overhead
  hatches of not less than the dimensions of a Type III exit, except that for
  airplanes with a passenger configuration of 35 seats or less, excluding
  pilots seats, the two required Type III side exits need be replaced by only
  one overhead hatch.
    (f) Flightcrew emergency exits. For airplanes in which the proximity of
  passenger emergency exits to the flightcrew area does not offer a convenient
  and readily accessible means of evacuation of the flightcrew, and for all
  airplanes having a passenger seating capacity greater than 20, flightcrew
  exits shall be located in the flightcrew area. Such exits shall be of
  sufficient size and so located as to permit rapid evacuation by the crew. One
  exit shall be provided on each side of the airplane; or, alternatively, a top
  hatch shall be provided. Each exit must encompass an unobstructed rectangular
  opening of at least 19 by 20 inches unless satisfactory exit utility can be
  demonstrated by a typical crewmember.

  [Doc. No. 24344, Admt. 25-72, 55 FR 29781, July 20, 1990]

  *****************************************************************************


  55 FR 29756, No. 140, July 20, 1990

    SUMMARY: These amendments to the Federal Aviation Regulations (FAR) update
  the standards for type certification of transport category airplanes for
  clarity and accuracy, and ensure that the standards are appropriate and
  practicable for the smaller transport category airplanes common to regional
  air carrier operation.

    EFFECTIVE DATE: August 20, 1990.

  *****************************************************************************
that should cover it..
8-)

--
Leo J.J. Kok
Structures Research & Development,                  Tel: (416)375-3363
de Havilland Inc.,Garratt Blvd., M/S: N18-06        FAX: (416)375-4537
DOWNSVIEW, Ontario, Canada M3K 1Y5                  E-MAIL: lkok@dehavilland.ca