(2) Water loads during inflation after water entry.
(C) Handling Qualities. Rotorcraft handling qualities should be verified to comply with the applicable regulations throughout the approved operating envelopes for:
(1) The deflated and stowed condition;
(2) The fully inflated condition; and
(3) The in-flight inflation condition. For float systems which may be inflated in flight, rotorcraft controllability should be verified by test or analysis assuming the most critical float compartment fails to inflate.
(3) Flotation and Trim. The flotation and trim characteristics should be investigated for a range of a sea states from zero to the maximum selected by the applicant and should be satisfactory in waves having height/length ratios of 1:12.5 for multiengine rotorcraft with Category A engine isolation and 1:10 for all other rotorcraft.
Flotation and trim characteristics should be demonstrated to be satisfactory to at least sea state 4 conditions.
(її) Flotation tests should be investigated at the most critical rotorcraft loading condition.
(ili) Flotation time and trim requirements should be evaluated with a simulated, ruptured deflation of the most critical float compartment. Flotation characteristics should be satisfactory in this degraded mode to at least sea state 2 conditions.
(iv) A sea anchor or similar device should not be used when demonstrating compliance with the flotation and trim requirements but may be used to assist in the deployment of liferafts. If the basic flotation system has demonstrated compliance with the minimum flotation and trim requirements, credit for a sea anchor or similar device to achieve stability in more severe water conditions (sea state, etc.) may be allowed if the device can be automatically, remotely, or easily deployed by the minimum flightcrew.
(v) Probable rotorcraft door/window open or closed configurations and probable damage to the airframe/hull (i.e., failure of doors, windows, skin, etc.) should be considered when demonstrating compliance with the flotation and trim requirements.
Par 338 429
(4) Float System Reliability. Reliability should be considered in the basic design to ensure approximately equal inflation of the floats to preclude excessive yaw, roll, or pitch in flight or in the water.
Maintenance procedures should not degrade the flotation system
(e.g., introducing contaminants which could affect normal operation, etc.).
(ii) The flotation system design should preclude inadvertent damage due to normal personnel traffic flow and excessive wear and tear. Protection covers should be evaluated for function and reliability.
(5) Occupant Egress and Survival. The ability of the occupants to deploy liferafts, egress the rotorcraft, and board the liferafts should be evaluated. For configurations which are considered to have critical occupant egress capabilities due to liferaft locations and/or ditching emergency exit locations and floats proximity, an actual demonstration of egress may be required. When a demonstration is required, it may be conducted on a full-scale rotorcraft actually immersed in a calm body of water or using any other rig/ground test facility shown to be representative. The demonstration should show that floats do not impede a satisfactory evacuation.
(6) Botorcraft Flight Manual. The Rotorcraft Flight Manual is an important element in the approval cycle of the rotorcraft for ditching. The material related to ditching may be presented in the form of a supplement or a revision to the basic manual. This material should include:
The information pertinent to the limitations applicable to the ditching approval. If the ditching approval is obtained in a segmented fashion (l.e., one applicant performing the aircraft equipment installation and operations portion and another designing and substantiating the liferaft/lifevest and ditching safety equipment installations and deployment facilities), the RFM limitations should state "Not Approved for Ditching" until all segments are completed. The requirements for a complete ditching approval not yet completed should be identified in the "Limitations" section.
(ii) Procedures and limitations for flotation device inflation.
(iii) Recommended rotorcraft water entry attitude, speed, and wave position.
(iv) Procedures for use of emergency ditching equipment.
(v) Procedures for ditching egress and raft entry.
430 Par 338
TABLE 338-1
SEA STATE CODE (WORLD METEOROLOGICAL ORGANIZATION) Sea State Significant Wave Height Wind Speed Code Description of Sea Meters Feet Knots Calm (Glassy) 0-3 Calm (Rippled) O to 0.1 O to 1/3 4-6 2 Smooth (Wavelets) 0.1 to 0.5 1/3 to 1 2/3 7-10 3 Slight 0.5 to 1.25 1 2/3 to 4 11-16
• 4 Moderate 1.25 to 2.5 4 to 8 17-21 5 Rough 2.5 to 4 8 to 13 22-27 6 Very Rough 4 to 6 13 to 20 28-47 7 High 6 to 9 20 to 30 48-55 Very High 9 to 14 30 to 45 56-63 9 Phenomenal Over 14 Over 45 64-118 NOTES: (1) The Significant Wave Height is defined as the average value of the height (vertical distance between trough and crest) of the largest one-third of the waves present.
(2) Maximum Wave Height is usually taken to be 1.6 x Significant Wave Height; e.g., Significant Wave Height or 6 meters gives Maximum Wave Height of 9.6 meters.
(3) Winds speeds were obtained from Appendix R of the "American Practical Navigatori by Nathaniel Bowditch, LL.D.; Published by the U.S. Naval Oceanographic Office, 1966.
Par 338 431
339. RESERVED.
Intentionally Left Blank 432 Par 339
340. § 27.807 (Amendment 27-21) EMERGENCY EXITS.
a. Explanation. The specified emergency exits are as follows:
(1) Quantity, size, and location.
(1) For typical operations.
Passenger Seating Capacity Main Door (MD) Side Side Opposite Main Door 1 through 15 MD (1) 19- by 26-inch ellipse More than 15 MD + additional (1) 19- by 26-inch ellipse + exit(s) additional exit(s) For overwater operations (if ditching certification is requested), one 19- by 26-inch elliptical exit on each side of the fuselage above the waterline.
(i1) Section 27.807(a) was revised by Amendment 27-21 on November 6, 1984, to remove any reference to the seating capacity in excess of 15 seats. For further information, see Amendment 29-21 which, in part, amended § 29.1 on January 31, 1983.
(2) In addition to quantity and size of exits, the rule specifies the following:
The 19- by 26-inch ellipse portion of the exit is to be unobstructed.
(її) The exits are to be readily accessible.
(i) The exits must have a simple and obvious method of opening.
(iv) The exits must be readily located and operated in darkness.
(v) The exits must be protected from jamming by fuselage deformation.
b. Procedures.
(1) The quantity and minimum size of exits will be as specified.
(2) Access to the exits will be provided by aisles, break-over seatbacks, or other features as appropriate. If access is questionable, a demonstration shall be conducted to assess the means of access.
(3) The location and operation of the exits should be evaluated in total darkness.
Par 340 433
(4) Protection from jamming is normally provided by clearances between the fuselage exit frame and the exit or by exit designs which are basically insensitive to fuselage deformation. NASTRAN or similar analysis methods have been used in the past to obtain the effects of fuselage deformation on exit clearances during minor crash landings.
340A. § 27.807 (Amendment 27-26) EMERGENCY EXITS.
a. Explanation. Amendment 27-26 added § 27.807(d)(3) which requires proof that all rotorcraft ditching configuration exits will also be free of interference from emergency flotation devices, whether stowed or deployed (inflated).
b. Procedures. All of the policy material pertaining to this section remains in effect with the following additions:
(1) Test, demonstration, compliance inspection, or analysis is required to show the "ditching" exits are free from interference from stowed/deployed emergency flotation devices. In the event an analysis is insufficient or a given design is questionable, a demonstrating may be required. The demonstration would consist, as a minimum, of an accurate, full-size replica (or representation) of the rotorcraft and of the flotation devices both before, during, an after their deployment.
(2) The type inspection authorization may be used to perform a detailed compliance evaluation utilizing a full-scale rotorcraft in calm water.
(3) Designs may be accepted "by compliance visual inspection" if location of exit and flotation devices relative to each other ensure that interference is impossible.
In this case, a demonstration is unnecessary.
341.-344. RESERVED.
434 (thru 438) Par 340
345. § 27.831 VENTILATION.
a. Explanation.
(1) This rule specifies minimum ventilation requirements for each passenger and crew compartment. The passenger and crew compartments are required to be free from harmful or hazardous concentration of gases or vapors, and specifically for carbon monoxide, its concentration may not exceed 1 part in 20,000 parts of air during forward flight or hovering in still air.
(2) Failure conditions must also be considered when evaluating the ventilation system, and § 27.1309 is used to cover these aspects. Malfunctions concerning the ventilation system are covered here to make the discussion complete in one paragraph.
(3) This system becomes more significant when engine bleed air is used for conditioning of the passenger and crew compartment's air. Certain data are necessary in order to properly analyze the bleed air provided under normal and malfunction conditions. The airframe manufacturer can normally look to the engine manufacturer for a specification of the maximum amount of air that can be extracted and the temperature of the extracted air. The engine manufacturer also normally provides a failure analysis that identifies ways the bleed air can be contaminated and the associated oil flow rates under each failure condition. The oil manufacturers are in a position to provide information regarding breakdown of the oil under different temperature conditions and the impact of that breakdown on the quality of the air being provided to the passenger and crew compartments.
b. Procedures.
(1) The passenger and crew compartments should be monitored under normal operating conditions for the presence of carbon monoxide. A carbon monoxide test kit is normally used for this evaluation. Air is monitored around crew stations, and outlets and different combinations of windows closed/open, heat off/on, air-conditioner off/on, etc., are checked to ensure all conditions are evaluated.
(2) When engine bleed air is used to condition the passenger and crew compartment's air, it should be initially substantiated that under normal operation, the amount of air being extracted does not exceed the limit established by the engine manufacturer. To accomplish this, determine the flight condition that will give the maximum bleed air flow through the flow limiter (venturi). The flow calculations should use this maximum flow condition and should also be made using the maximum tolerance diameter of the venturi throat.
(3) The engine bleed air should also be evaluated under malfunction conditions to determine a worst-case air contamination condition. (A typical worst-case malfunction is for an oil seal to fail in the engine that allows the engine oil supply to be Par 345 439
introduced into the airflow.) With information regarding the contaminant, flow rate calculations can be made to predict the contamination levels that will be reached in the passenger and crew compartment's and also the associated time duration of passenger and crew exposure. The severity of the exposure to the contaminated air is related to the temperature of the oil when it is introduced into the airflow. For example, synthetic base oils manufactured to MIL-L-7808 or MIL-L-23699 begin to break down into toxic components when the temperature exceeds 300° C (572° F). The oil manufacturers have evaluated this problem and should be in a position to provide data regarding the amount and type of toxic components to be expected, and the effect of introducing those components into the passenger and crew compartments. Therefore, from information supplied by the engine manufacturer, the worst-case air contamination condition can be calculated, and this can be compared with results of the oil manufacturers' tests to determine if the concentrations are harmful or hazardous.
346. § 27.833 (Amendment 27-23) HEATERS.
a. Explanation.
(1) Amendment 27-23 added § 27.833 for combustion heaters which is derived from the lead-in paragraph of § 27.859(c) which relates to the fire protection requirements for fuel heaters. Section 27.833 was needed to facilitate the extensive changes made to § 27.859 and to achieve parallel rule construction with Part 29. This will ensure that all combustion heaters will be approved whether as a part of the type design or as a TSO approved combustion heater.
(2) Section 27.833 requires that each combustion heater be approved. The standard contains no provisions regarding functioning of the system, environmental considerations, or malfunctions; therefore, the provisions of §§ 27.1301 and 27.1309 should be used to evaluate those aspects of an installation. The ventilation provisions of § 27.831 should be considered as well as the fire protection and installation provisions of § 27.859.
b. Procedures.
(1) Technical Standard Order, TSO-C20, was issued June 15, 1949, and amended on April 16, 1951, and concerns combustion heaters. If a heater chosen for installation is qualified to the provisions of TSO-C20, it may be approved. If a unit is not TSO qualified, a qualification program for the heater itself in conjunction with the installation should be established. This program under the type design change procedures should be equal or equivalent to provisions of the TSO-C20.
(2) The TSO refers to the SAE Aeronautical Standard, AS 143B, which specifies the use of certain additional devices, design features, air supply considerations, performance tests, safety controls, environmental considerations, and so forth. Compliance with all of the provisions of the Aeronautical Standard should 440 Par 345
result in an approved unit; however, it will not necessarily result in a satisfactory installation. For environmental considerations, an environmental spectrum more suitable to rotorcraft may be used by referring to the latest version of Document No. RTCA/DO-160, Environmental Conditions and Test Procedures for Airborne Equipment, rather than the older AS 143B. Similarly, other specifications may also be satisfactory for compliance with the standard.
(3) The heater system installation evaluation should also consider functioning of the system based upon the provisions of § 27.1301 (see Paragraph 617 of this AC).
Section 27.1309(a) is the regulatory basis for also considering environmental conditions (see Paragraph 621 of this AC). The expected environmental conditions resulting from the particular rotorcraft installation should be compared to those specified in the TSO.
If the conditions derived for § 27.1309 are not met, additional environmental considerations are appropriate. The provisions of § 27.1309(b) should be used to evaluate the possible malfunctions of the installed system. Such an evaluation should be documented in a fault analysis. The air quality provisions of § 27.831 apply since certain standards of "ventilation air quality," under normal and malfunction conditions, should comply (see Paragraph 345 of this AC). The provisions of § 27.859 apply. See Paragraph 360 of this AC for information.
347.-356. RESERVED.
Par 346 441(thru 451.
7/30/97 AC 27-1A SECTION 21. FIRE PROTECTION Intentionally Left Blank Par 357 452
357. RESERVED.
Intentionally Left Blank Par 357 453
358. § 27.853 (Amendment 27-17) COMPARTMENT INTERIORS.
a. Explanation.
(1) Crew and passenger compartments must have materials that are at least flash resistant or flame resistant as prescribed for the application cited in the standard.
(2) Whenever smoking is allowed, self-contained, removable ashtrays must be provided as stated. A placard or placards, if needed, may be used to prohibit smoking at all times in the crew and passenger compartment. If smoking is allowed, illuminated "no smoking" signs are required. The signs shall meet prescribed standards for passenger compartments that are separate from the flightcrew. Integral crew and passenger compartments (of smaller rotorcraft) do not require illuminated signs since oral commands or instructions from the flightcrew are sufficient.
(3) Amendment 27-17 revised Paragraph (c) of this section by adding the standards for the "no smoking" illuminated signs that must be controllable by the flightcrew. Amendment 29-18 added the same standards for FAR Part 29 transport rotorcraft. The standard requires at least one illuminated sign for use in daylight as well as night in passenger compartments that are separate from the crew compartment.
The sign shall be legible to each seated passenger. If forward and aft facing seats are installed, signs for each seat orientation may be needed as prescribed.
Section 29.853(c) of Amendment 29-18 is the same standard as § 27.853(c) of Amendment 27-17.
(4) Advisory Circular 23-2, Flammability Tests, August 20, 1984, provides historical background of the regulatory standards for flash resistant, flame resistant, fire resistant, and fireproof materials. The procedures in AC 23-2 may be used for FAR Part 27 standards. Section 27.853 does not impose standards for mandatory use of self-extinguishing materials. Nevertheless, the FAA/AUTHORITY encourages and recommends use of self-extinguishing interior materials that comply with § 29.853 of Amendment 29-17.
(5) Flammability standards for certain electrical wires or cables are specified in § 27.1365. See Paragraph 659 of this AC for information about electrical wires.
b. Procedures.
(1) Aircraft interior materials including consoles, cabinets, etc., are subject to the standards.
(2) Advisory Circular 23-2 may be referred to in preparation of test proposals for flammability tests of interior materials.
454 Par 358