(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.
(Amendment 25-0)
(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)
(5) Paragraph (e). Direct visual inspection. The means of complying with paragraph
(e) of this section will depend upon the type of door and locking mechanism used. In all cases there should be provisions to ascertain that an unsatisfactory condition does not exist after closing the door. In some instances a central window for viewing the position of the mechanism may be sufficient while other cases may require one or more windows in the door frame to permit inspection of the bayonet location relative to that portion of the lock in the door frame.
The need for or the number and location of inspection openings or windows will depend on the type of door and locking mechanism used. (Amendment 25-0)
(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)
(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)
(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.
(Amendment 25-0)
62. AMENDMENT 25-15, Effective October 24, 1967.
a. Regulation.
(a) Each cabin must have at least one easily accessible external door.
(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.
(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.
(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.
(e) There must be a provision for direct visual inspection of the locking mechanism by crewmembers to determine whether external doors, for which the initial opening movement is outward (including passenger, crew, service, and cargo doors), are fully locked. In addition, there must be a visual means to signal to appropriate crewmembers when normally used external doors are closed and fully locked.
(f) Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure.
[(g) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit. If an integral stair is installed at such a passenger entry door, the stair must be designed so that when subjected to the inertia forces specified in § 25.561, and following the collapse of one or more legs of the landing gear, it will not interfere to an extent that will reduce the effectiveness of emergency egress through the passenger entry door.]
b. Guidance.
(l) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the
23 main cabin door. Cargo and service doors not suitable for emergency egress need only comply with § 25.783(e) and be safeguarded against opening in flight as a result of mechanical failure.
(Amendment 25-0)
(2) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)
(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)
(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.
(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)
(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-
0)
(3) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)
(4) Paragraphs (b) and (e). Means for safeguarding against inadvertent opening in flight. Auxiliary locking devices may be used to reduce the probability of inadvertent opening in flight provided they meet the standards and conditions covered above. (Amendment 25-0)
(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.
(Amendment 25-0)
(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)
(5) Paragraph (e). Direct visual inspection. The means of complying with paragraph
(e) of this section will depend upon the type of door and locking mechanism used. In all cases there should be provisions to ascertain that an unsatisfactory condition does not exist after closing the door. In some instances a central window for viewing the position of the mechanism may be sufficient while other cases may require one or more windows in the door frame to permit inspection of the bayonet location relative to that portion of the lock in the door frame.
The need for or the number and location of inspection openings or windows will depend on the type of door and locking mechanism used. (Amendment 25-0)
(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)
(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)
(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in
25 loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.
(Amendment 25-0)
63. AMENDMENT 25-23, Effective May 8, 1970.
a. Regulation.
(a) Each cabin must have at least one easily accessible external door.
(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure [or failure of a single structural element]). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.
(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.
(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.
(e) There must be a provision for direct visual inspection of the locking mechanism by crewmembers to determine whether external doors, for which the initial opening movement is outward (including passenger, crew, service, and cargo doors), are fully locked. In addition, there must be a visual means to signal to appropriate crewmembers when normally used external doors are closed and fully locked.
(f) Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure [or failure of a single structural element].
(g) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit. If an integral stair is installed at such a passenger entry door, the stair must be designed so that when subjected to the inertia forces specified in § 25.561, and following the collapse of one or more legs of the landing gear, it will not interfere to an extent that will reduce the effectiveness of emergency egress through the passenger entry door.
b. Guidance.
(l) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. Cargo and service doors not suitable for emergency egress need only comply with § 25.783(e) and be safeguarded against opening in flight as a result of mechanical failure.
(Amendment 25-0)
(2) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)
(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)
(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.
(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)
(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-
0)
(3) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The
27 loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)
(4) Paragraphs (b) and (e). Means for safeguarding against inadvertent opening in flight. Auxiliary locking devices may be used to reduce the probability of inadvertent opening in flight provided they meet the standards and conditions covered above. (Amendment 25-0)
(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.
(Amendment 25-0)
(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)
(5) Paragraph (e). Direct visual inspection. The means of complying with paragraph
(e) of this section will depend upon the type of door and locking mechanism used. In all cases there should be provisions to ascertain that an unsatisfactory condition does not exist after closing the door. In some instances a central window for viewing the position of the mechanism may be sufficient while other cases may require one or more windows in the door frame to permit inspection of the bayonet location relative to that portion of the lock in the door frame.
The need for or the number and location of inspection openings or windows will depend on the type of door and locking mechanism used. (Amendment 25-0)
(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)
(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)
(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.
(Amendment 25-0)
64. AMENDMENT 25-54, Effective October 14, 1980.
a. Regulation.
(a) Each cabin must have at least one easily accessible external door.
(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure or failure of a single structural element [either during or after closure]). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.
(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.
(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.
[(e) There must be a provision for direct visual inspection of the locking mechanism to determine if external doors, for which the initial opening movement is not inward (including passenger, crew, service, and cargo doors), are fully closed and locked.
The provision must be discernible under operational lighting conditions by appropriate crewmembers using a flashlight or equivalent lighting source. In addition, there must be a visual warning means to signal the appropriate flight crewmembers if any external door is not fully closed and locked. The means must be designed such that any failure or combination of failures that would result in an erroneous closed and locked indication is improbable for doors for which the initial opening movement is not inward.
(f) External doors must have provisions to prevent the initiation of pressurization of the airplane to an unsafe level if the door is not fully closed and locked. In addition,
29 it must be shown by safety analysis that inadvertent opening is extremely improbable.] [(g)] Cargo and service doors not suitable for use as an exit in an emergency need only meet paragraph (e) of this section and be safeguarded against opening in flight as a result of mechanical failure or failure of a single structural element.
(h) Each passenger entry door in the side of the fuselage must qualify as a Type A, Type I, or Type II passenger emergency exit and must meet the requirements of §§ 25.807 through 25.813 that apply to that type of passenger emergency exit.
(i) If an integral stair is installed in a passenger entry door that is qualified as a passenger emergency exit, the stair must be designed so that under the following conditions the effectiveness of passenger emergency egress will not be impaired:
(1) The door, integral stair, and operating mechanism have been subjected to the inertia forces specified in § 25.561(b)(3), acting separately relative to the surrounding structure.
[(2) The airplane is in the normal ground attitude and in each of the attitudes corresponding to collapse of one or more legs of the landing gear.
(j) All lavatory doors must be designed to preclude anyone from becoming trapped inside the lavatory, and if a locking mechanism is installed, it be capable of being unlocked from the outside without the aid of special tools.]
b. Guidance.
(1) Refer to § 25.809 for related requirements, and AC 25.783-1, “Fuselage, Doors, Hatches, and Exits,” dated 12/10/86, for related guidance. (Amendment 25-54)
(2) Paragraph (b). Protection against inadvertent exit door openings is required, but at the same time, a single-motion handle operation to open a passenger door should be provided to facilitate emergency egress. Auxiliary locking devices that complicate the door opening process may be accepted as necessary, though undesirable, if it can be substantiated that there is no other practicable means of protecting against inadvertent exit door opening. (Amendment 25-54)
(i) Auxiliary locking devices that may initially be assumed to be necessary, in fact might be eliminated by assuring that the door is designed in accordance with human factors principles. A door that is opened by moving a handle from the up position to a down position represents a design contrary to the convention believed to be familiar to most people in the aircraft industry. Therefore, this design may lend itself to contributing to an inadvertent door opening, as has actually happened. In addition, a door handle that is in the up position when the door is closed lends itself to more easily being used as a handhold in flight, which may result in an inadvertent opening. The threat inherent in this design would practically mandate the inclusion of auxiliary locking devices, to the possible detriment of emergency egress capability.
30 On the other hand, a door handle which operates in a conventional manner (i.e., moves up to open, moves down to close) is not as prone to inappropriate operation, nor is it in a location as susceptible for use as a handhold in flight. Consequently, this design, in addition to being more user-friendly from a human factors viewpoint, may eliminate any need for auxiliary locking devices. (Amendment 25-54)
(ii) Handles which operate in a rotary manner (in a plane parallel to that of the door) are not known to have been implicated in any incidents as noted above, nor has clockwise versus counterclockwise rotary motion been known to be controversial in this regard (except that counterclockwise may be the most universally accepted convention for opening jars, faucets, etc.). Likewise, these handles have not been considered to represent the attractive handhold devices in flight that other types of handles might and, furthermore, they require a deliberate effort to actuate. (Amendment 25-54)
(iii) When it can be substantiated to the satisfaction of the FAA that auxiliary locking devices are necessary to comply with the inadvertent door opening requirements of §§ 25.783(a) and 25.809(f), and it is not through design defect that these devices are provided, any potentially adverse impact of these devices on emergency egress must be minimized through adherence to the available guidance pertinent to auxiliary locking devices. "Design defect" in this context may reasonably be considered to include designs which neglect to address known human factors concerns as highlighted herein. Auxiliary locking devices which are deemed to be not simple and obvious, are not acceptable. Devices which are hidden by design or color, recessed, contoured, camouflaged, or otherwise concealed to the degree that a naive person may need to read a placard to determine how to open the door are not simple and obvious, and are therefore not acceptable. Suitable demonstrations may be required to substantiate acceptability in this regard. (Amendment 25-54)
(3) Paragraphs (b) through (e). The requirements of these paragraphs apply to all cabin and pilot compartment external doors usable for entrance or egress. It is not restricted to the main cabin door. (Amendment 25-0)
(4) Paragraph (b). Auxiliary locking devices. (Amendment 25-0)
(i) The use of auxiliary locking devices is permitted. Such devices would include dual locking handles, other types of locking and safety devices, two position handles, and dual operation handles (where one operation such as pushing or pulling on the handle unlocks the latching mechanism and the second operation of turning the handle unlatches the door for opening). Auxiliary locking devices should be used only as an additional safety factor and should not be used as a means of correcting an inadequate design of the primary locking or latching means. The advantages to be gained from the installation of auxiliary or dual locking devices (safety chains and dual handle main locking means) should be weighed against the need to easily and rapidly open the door in case of emergencies so that the overall level of safety is as high as practicable. (Amendment 25-0)
(ii) All locking or safety means, including safety chains and latches of any kind, should be so positioned and designed that their presence, location and means of operation are obvious to one not familiar with door designs. (Amendment 25-0) (A) The means of fastening safety devices should be sufficiently simple to make removal easy. (Amendment 25-0) (B) Any emergency release mechanism installed to release the safety device should operate with a simple motion and upon the application of relatively small forces.
(Amendment 25-0) (C) All locking devices should be readily operable from both inside and outside of the airplane and be appropriately marked both inside and outside. (Amendment 25-0)
(iii) Auxiliary safety devices meeting the standards of paragraph (ii) above may be fastened in place during the entire flight. It will not be necessary to have such devices unlatched during takeoff and landing. Auxiliary safety devices such as safety chains or bars that do not meet the standards of paragraph (ii) above may be used provided operating instructions are installed at or near the device and a placard is installed requiring the removal of such devices prior to takeoff and landing. For related guidance, Refer to paragraph 351b(3). (Amendment 25-
0)
(5) Paragraph (b). Power operated external doors. Power operated doors should be so designed that the door can be opened by manual means even when power is inactivated. The loss of power should not cause the door to become unlatched. Since emergency landings, such as the wheels-up condition, may result in the severance of electrical wires or rupture of hydraulic and pneumatic lines, the power which may be needed for operation of the doors or exits may be lost. Similarly, it is conceivable that under emergency conditions, the electrical power source may be purposely interrupted to reduce the possibility of fire. (Amendment 25-0)
(i) It is acceptable to create a limited access zone in front of the door to eliminate the possibility of a passenger using the door handle as a steadying means and thereby inadvertently opening the door. Although providing a restricted zone by means of a barrier may appear to conflict with the requirements of § 25.813 for an unobstructed passageway to Type I, and Type II emergency exits, it is considered that it would contribute sufficiently to the overall safety of the airplane occupants to be permitted. This device may be a rope, chain, rigid bar or gate. Such installations should be waist high to provide the maximum benefits for an adult and the end fastenings should be simple to make removal easy. It is not considered acceptable to install full-length auxiliary doors, but waist-high rigid gates would be acceptable provided they open toward the door and will not block the opening of the cabin door in any way. The locking means should be one, which could be easily overridden such as a spring-loaded ball type latch.
(Amendment 25-0)
(ii) Flexible gates such as those made from webbing are not acceptable on the basis that persons may become entangled during an emergency egress. The use of a barrier to prevent persons from inadvertently opening the door in flight does not eliminate the need for a safety
32 means to provide for possible malfunctioning of the primary locking mechanism; however, the auxiliary safety means covered above may eliminate the need for a restricted zone. (Amendment 25-0)
(6) Paragraph (e). Visual indicating system. The objective herein is to be able to ascertain by visual means that the door or locking means is sufficiently engaged to eliminate hazards emanating from an improperly closed door. Outward opening doors present a different problem from inward opening doors. (Amendment 25-0)
(i) The visual indicating system may consist of an indicator for each individual door, or a system connecting all doors in series. If the latter system is used, it need not necessarily show which door is not fully locked. (Amendment 25-0)
(ii) It is not necessary that more than one crewmember be able to ascertain by a visual signal that all external doors, normally used by the crew in supplying the airplane, or in loading and unloading passengers and cargo, are fully closed and locked. The visual signal should be located so that it may easily be seen by the appropriate crewmember from his station.
(Amendment 25-0)
65. AMENDMENT 25-72, Effective August 20, 1990.
a. Regulation.
(a) Each cabin must have at least one easily accessible external door.
(b) There must be a means to lock and safeguard each external door against opening in flight (either inadvertently by persons or as a result of mechanical failure or failure of a single structural element either during or after closure). Each external door must be openable from both the inside and the outside, even though persons may be crowded against the door on the inside of the airplane. Inward opening doors may be used if there are means to prevent occupants from crowding against the door to an extent that would interfere with the opening of the door. The means of opening must be simple and obvious and must be arranged and marked so that it can be readily located and operated, even in darkness. Auxiliary locking devices may be used.
(c) Each external door must be reasonably free from jamming as a result of fuselage deformation in a minor crash.
(d) Each external door must be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.
(e) There must be a provision for direct visual inspection of the locking mechanism to determine if external doors, for which the initial opening movement is not inward (including passenger, crew, service, and cargo doors), are fully closed and locked.
The provision must be discernible under operational lighting conditions by appropriate crewmembers using a flashlight or equivalent lighting source. In