165 SECTION 25.793 FLOOR SURFACES
161. Section 25.793 Did Not Exist Prior to Amendment 25-51.
162. AMENDMENT 25-51, Effective March 6, 1980.
a. Regulation.
The floor surface of all areas which are likely to become wet in service must have slip resistant properties.
b. Guidance. Military Specifications Mil-W-5044B and Mil-W-5044C, titled "Walkway Compound, Nonslip and Walkway Matting, Nonslip,” measure dynamic coefficient of friction and provide an acceptable standard for the slip resistant properties when a minimum dynamic coefficient of friction of 0.45 is measured. This is an acceptable measure for this section and for § 25.803. (Amendment 25-51) 163 - 210. [RESERVED]
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167 SECTION 25.795 SECURITY CONSIDERATIONS
211. Section 25.795 Did Not Exist Prior to Amendment 25-106.
212. AMENDMENT 25-106, Effective January 15, 2002.
a. Regulation.
[(a) Protection of flightdeck. If a flightdeck door is required by operating rules, the door installation must be designed to:
(1) Resist forcible intrusion by unauthorized persons and be capable of withstanding impacts of 300 Joules (221.3 foot-pounds) at the critical locations on the door, as well as a 250 pound (1113 Newtons) constant tensile load on the knob or handle, and
(2) Resist penetration by small arms fire and fragmentation devices to a level equivalent to level IIIa of the National Institute of Justice Standard (NIJ) 0101.04.
(b) [Reserved]]
b. Guidance.
(1) Paragraph (a)(1). Refer to AC 25.795-1A, “Flightdeck Intrusion Resistance.”
(Amendment 25-106)
(2) Paragraph (a)(1). Refer to Appendix 11, FAA Memorandum, 01-115-11, Original Release: dated November 6, 2001, Revision dated December 3, 2002, “Subject: Certification of Strengthened Flightdeck Doors on Transport Category Airplanes.” This memorandum outlines acceptable means of compliance with this paragraph and many other regulatory requirements that were affected by Amendment 25-106. (Amendment 25-106)
(3) Paragraph (a)(2). Refer to AC 25.795-2A, “Flightdeck Penetration Resistance.”
(Amendment 25-106)
(4) Paragraph (a)(2). Refer to Appendix 11, FAA Memorandum, 01-115-11, Original Release: dated November 6, 2001, Revision dated December 3, 2002, “Subject: Certification of Strengthened Flightdeck Doors on Transport Category Airplanes.” This memorandum outlines acceptable means of compliance with this paragraph and many other regulatory requirements that were affected by Amendment 25-106. (Amendment 25-106) 213 - 250. [RESERVED]
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169 SECTION 25.801 DITCHING
251. REGULATION IN EFFECT AT ADOPTION OF PART 25.
a. Regulation.
(a) If certification with ditching provisions is requested, the airplane must meet the requirements of this section and §§ 25.807(d), 25.1411, and 25.1415(a).
(b) Each practicable design measure, compatible with the general characteristics of the airplane, must be taken to minimize the probability that in an emergency landing on water, the behavior of the airplane would cause immediate injury to the occupants or would make it impossible for them to escape.
(c) The probable behavior of the airplane in a water landing must be investigated by model tests or by comparison with airplanes of similar configuration for which the ditching characteristics are known. Scoops, flaps, projections, and any other factor likely to affect the hydrodynamic characteristics of the airplane, must be considered.
(d) It must be shown that, under reasonably probable water conditions, the flotation time and trim of the airplane will allow the occupants to leave the airplane and enter the liferafts required by § 25.1415. If compliance with this provision is shown by buoyancy and trim computations, appropriate allowances must be made for probable structural damage and leakage. If the airplane has fuel tanks (with fuel jettisoning provisions) that can reasonably be expected to withstand a ditching without leakage, the jettisonable volume of fuel may be considered as buoyancy volume.
(e) Unless the effects of the collapse of external doors and windows are accounted for in the investigation of the probable behavior of the airplane in a water landing (as prescribed in paragraphs (c) and (d) of this section), the external doors and windows must be designed to withstand the probable maximum local pressures.
b. Guidance.
(l) Background Information. The expression "reasonably probable water conditions" is considered judgmental in application to compliance for ditching and has never been specifically defined as to sea state force or wave height. Early ditching investigations of dynamic models were conducted by the National Advisory Committee for Aeronautics (NACA) at Langley Field, Virginia, and NACA Report 1347, issued in 1958. A compilation of such test results, set the precedence for early and modern transport airplane designers in substantiating airplanes for ditching by analyses. Such early tests were based on calm-water landings with the supposition
170 that rough-water landings of particular models that were made parallel to waves or swells would exhibit the same general type of performance. Later rough-water ditching investigations of models were conducted and their results were compiled in documents such as Technical Note No. D-101, issued by the National Aeronautics and Space Administration (NASA) in 1959, and Also referred to by designers in respective ditching analyses. In addition to the reference to actual ditching incidents, it became an acceptable practice for designers to substantiate the ditching behavior of a proposed airplane design by comparisons in basic geometric configuration to airplane designs approved for ditching by the models tested at Langley Field. Parametric comparisons usually revealed some identicalness in geometric aspects and where obvious discrepancies in dimensional relationships were evident, predetermined correction factors were applied. (Amendment 25-0)
(2) Paragraph (b). Ditching load factors may be determined by model tests. Landing procedures or design measures must be established that limit the factors to those listed in § 25.561. Load factors above these are considered to expose occupants to injurious loads. In addition, standard parts such as seats, belts, and harnesses are designed to § 25.561 load factors.
Higher load factors in the downward direction may be acceptable provided the structural components are designed for the higher loads and also provided it can be shown that the occupants are protected from serious injury under these loads. (Amendment 25-0)
(3) Paragraph (d). A maximum permissible evacuation time for liferafts per the rule is also considered judgmental in scope for ditching compliance. During certification, it is usually shown by analysis that an airplane will float for a period of time exceeding the most conservative estimate of time required to completely evacuate the airplane. Evacuation times and rates for liferaft type devices are normally established by analysis and included in the particular airplane model ditching and flotation document presented for approval during type certification.
(Amendment 25-0)
(4) Paragraph (d). Prior to approval of any size or type of transport airplane for ditching approval under § 25.801, there must be evidence of an engineering evaluation of the provisions for installing the emergency equipment specified in § 25.1411. (Amendment 25-0)
(5) Paragraph (d). In approving an airplane for overwater flight certification, two ditching conditions are examined. The first condition is the "planned ditching" case in which there is sufficient time to prepare the airplane for ditching and adjustments have been made to airplane weight and c.g. to account for loss of such items as engines, nacelles, and trailing edge flaps on impact with the water. The other condition is the "unplanned ditching" (§ 25.807(d)) case in which the airplane enters the water with insufficient time to prepare for ditching. The most critical situation for this case is at maximum gross weight due to a failed or aborted takeoff.
No airplane damage is considered for the "unplanned ditching" case. (Amendment 25-0)
(6) Paragraph (d). As to ditching structural criteria, external pressures must be determined for the fuselage and all external doors and exits that are subject to hydrodynamic forces. This can be determined by measurements on ditching models or by analysis based on tests. Section 25.533, "Hull and Main Float Bottom Pressure Loads," may be a source of some pressure information if similarity can be shown. The use of pressure distribution data from similar model airplanes is acceptable and is preferred over purely analytical methods.
(Amendment 25-0)
252. AMENDMENT 25-72, Effective August 20, 1990.
a. Regulation.
(a) If certification with ditching provisions is requested, the airplane must meet the requirements of this section and §§ 25.807[(e)], 25.1411, and 25.1415(a).
(b) Each practicable design measure, compatible with the general characteristics of the airplane, must be taken to minimize the probability that in an emergency landing on water, the behavior of the airplane would cause immediate injury to the occupants or would make it impossible for them to escape.
(c) The probable behavior of the airplane in a water landing must be investigated by model tests or by comparison with airplanes of similar configuration for which the ditching characteristics are known. Scoops, flaps, projections, and any other factor likely to affect the hydrodynamic characteristics of the airplane, must be considered.
(d) It must be shown that, under reasonably probable water conditions, the flotation time and trim of the airplane will allow the occupants to leave the airplane and enter the liferafts required by § 25.1415. If compliance with this provision is shown by buoyancy and trim computations, appropriate allowances must be made for probable structural damage and leakage. If the airplane has fuel tanks (with fuel jettisoning provisions) that can reasonably be expected to withstand a ditching without leakage, the jettisonable volume of fuel may be considered as buoyancy volume.
(e) Unless the effects of the collapse of external doors and windows are accounted for in the investigation of the probable behavior of the airplane in a water landing (as prescribed in paragraphs (c) and (d) of this section), the external doors and windows must be designed to withstand the probable maximum local pressures.
b. Guidance.
(l) Background Information. The expression "reasonably probable water conditions" is considered judgmental in application to compliance for ditching and has never been specifically defined as to sea state force or wave height. Early ditching investigations of dynamic models were conducted by the National Advisory Committee for Aeronautics (NACA) at Langley Field, Virginia, and NACA Report 1347, issued in 1958. A compilation of such test results, set the
172 precedence for early and modern transport airplane designers in substantiating airplanes for ditching by analyses. Such early tests were based on calm-water landings with the supposition that rough-water landings of particular models that were made parallel to waves or swells would exhibit the same general type of performance. Later rough-water ditching investigations of models were conducted and their results were compiled in documents such as Technical Note No. D-101, issued by the National Aeronautics and Space Administration (NASA) in 1959, and Also referred to by designers in respective ditching analyses. In addition to the reference to actual ditching incidents, it became an acceptable practice for designers to substantiate the ditching behavior of a proposed airplane design by comparisons in basic geometric configuration to airplane designs approved for ditching by the models tested at Langley Field. Parametric comparisons usually revealed some identicalness in geometric aspects and where obvious discrepancies in dimensional relationships were evident, predetermined correction factors were applied. (Amendment 25-0)
(2) Paragraph (b). Ditching load factors may be determined by model tests. Landing procedures or design measures must be established that limit the factors to those listed in § 25.561. Load factors above these are considered to expose occupants to injurious loads. In addition, standard parts such as seats, belts, and harnesses are designed to § 25.561 load factors.
Higher load factors in the downward direction may be acceptable provided the structural components are designed for the higher loads and also provided it can be shown that the occupants are protected from serious injury under these loads. (Amendment 25-0)
(3) Paragraph (d). A maximum permissible evacuation time for liferafts per the rule is also considered judgmental in scope for ditching compliance. During certification, it is usually shown by analysis that an airplane will float for a period of time exceeding the most conservative estimate of time required to completely evacuate the airplane. Evacuation times and rates for liferaft type devices are normally established by analysis and included in the particular airplane model ditching and flotation document presented for approval during type certification.
(Amendment 25-0)
(4) Paragraph (d). Prior to approval of any size or type of transport airplane for ditching approval under § 25.801, there must be evidence of an engineering evaluation of the provisions for installing the emergency equipment specified in § 25.1411. (Amendment 25-0)
(5) Paragraph (d). In approving an airplane for overwater flight certification, two ditching conditions are examined. The first condition is the "planned ditching" case in which there is sufficient time to prepare the airplane for ditching and adjustments have been made to airplane weight and c.g. to account for loss of such items as engines, nacelles, and trailing edge flaps on impact with the water. The other condition is the "unplanned ditching" (§ 25.807(e)) case in which the airplane enters the water with insufficient time to prepare for ditching. The most critical situation for this case is at maximum gross weight due to a failed or aborted takeoff.
No airplane damage is considered for the "unplanned ditching" case. (Amendment 25-0)
(6) Paragraph (d). As to ditching structural criteria, external pressures must be determined for the fuselage and all external doors and exits that are subject to hydrodynamic forces. This can be determined by measurements on ditching models or by analysis based on
173 tests. Section 25.533, "Hull and Main Float Bottom Pressure Loads," may be a source of some pressure information if similarity can be shown. The use of pressure distribution data from similar model airplanes is acceptable and is preferred over purely analytical methods.
(Amendment 25-0) 253 - 270. [RESERVED]
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175 SECTION 25.803 EMERGENCY EVACUATION
271. REGULATION IN EFFECT AT ADOPTION OF PART 25.
a. Regulation.
(a) Each crew and passenger area must have emergency means to allow rapid evacuation in crash landings, with the landing gear extended and retracted, considering the possibility of the airplane being on fire.
(b) The passenger and crew access doors and service doors may be considered as emergency exits if they meet the applicable requirements of this section and §§ 25.805 and 25.813.
(c) If the airplane is divided into separate compartments without the minimum unobstructed passageway between compartments required by § 25.813, this section and §§ 25.805 through 25.815 apply to each compartment independently.
b. Guidance. Paragraph (a). When installed above passenger egress paths, any features that hang (signs, video monitors etc.) from the ceiling or span across passenger egress paths (e.g., class dividers and curtain headers) should be at least 73-inches above the floor (top of the floor covering), unless they are retractable and are placarded to be retracted for taxi, takeoff, and landing (TT&L). For airplanes that do not have 73-inches between the floor and the ceiling panels, any features that hang (signs, video monitors, etc.) from the ceiling should not be positioned in the passenger cabin egress paths. Alternate locations should be used, e.g., over seat, on the side wall, etc. These features should also be appropriately padded or rounded to preclude injury when persons are moving about the cabin. (Amendment 25-0)
272. AMENDMENT 25-1, Effective June 7, 1965.
a. Regulation.
(a) Each crew and passenger area must have emergency means to allow rapid evacuation in crash landings, with the landing gear extended and retracted, considering the possibility of the airplane being on fire.
(b) The passenger and crew access doors and service doors may be considered as emergency exits if they meet the applicable requirements of this section and §§ 25.805 and 25.813.
[(c) Deleted]
b. Guidance. Paragraph (a). When installed above passenger egress paths, any features that hang (signs, video monitors etc.) from the ceiling or span across passenger egress paths (e.g.,
176 class dividers and curtain headers) should be at least 73-inches above the floor (top of the floor covering), unless they are retractable and are placarded to be retracted for taxi, takeoff, and landing (TT&L). For airplanes that do not have 73-inches between the floor and the ceiling panels, any features that hang (signs, video monitors, etc.) from the ceiling should not be positioned in the passenger cabin egress paths. Alternate locations should be used, e.g., over seat, on the side wall, etc. These features should also be appropriately padded or rounded to preclude injury when persons are moving about the cabin. (Amendment 25-0)
273. AMENDMENT 25-15, Effective October 24, 1967.
a. Regulation.
(a) Each crew and passenger area must have emergency means to allow rapid evacuation in crash landings, with the landing gear extended and retracted, considering the possibility of the airplane being on fire.
[(b) Passenger ventral and tail cone, crew access, and service doors may be considered as emergency exits if they meet the applicable requirements of this section and §§ 25.805 through 25.813.
(c) Except as provided in paragraph (d) of this section, on airplanes having a seating capacity of more than 44 passengers, it must be shown by actual demonstration that the maximum seating capacity, including the number of crewmembers required by the operating rules, for which certification is requested can be evacuated from the airplane to the ground within 90 seconds. Evacuees using stands or ramps allowed by subparagraph (8) of this paragraph are considered to be on the ground when they are on the stand or ramp, provided that the acceptance rate of the stand or ramp is no greater than the acceptance rate of the means available on the airplane for descent from the wing during an actual crash situation. The demonstration must be conducted under the following conditions:
(1) It must be conducted either during the dark of the night or during daylight with the dark of the night simulated, utilizing only the emergency lighting system and utilizing only the emergency exits and emergency evacuation equipment on one side of the fuselage, with the airplane in the normal ground attitude, with landing gear extended.
(2) All emergency equipment must be installed in accordance with specified limitations of the equipment.
(3) Each external door and exit, and each internal door and curtain must be in a configuration to simulate a normal takeoff.
(4) Seat belts and shoulder harnesses (as required) must be fastened.