b. Procedures.
(1) The performance requirements of this standard are normally evaluated by a flight test pilot, and usually are included in the Type Inspection Authorization as part of the evaluation to be conducted at night.
(2) The installation of the landing light units) should be very carefully evaluated. Many of the units provided are stowed until needed and then driven to their operating position by an electric motor. If this type of light unit is provided, the possibility of its contact with fuel fumes should be considered. Installations that have this problem normally require the use of light units qualified as explosion proof. The installation should also be reviewed to determine if a single failure can cause the light to be on in the stowed position. If the light can be on, the potential for overheat or fire in the adjacent area should be considered.
670. § 27.1385 POSITION LIGHT SYSTEM INSTALLATION. Refer to Advisory Circular 20-74, "Aircraft Position and Anticollision Light Measurements."
671. § 27.1387 (Amendment 27-7) POSITION LIGHT SYŞTEM DIHEDRAL ANGLES. Refer to Advisory Circular 20-74.
672. § 27.1389 POSITION LIGHT DISTRIBUTION AND INTENSITIES. Refer to Advisory Circular 20-74.
673. § 27.1391 MINIMUM INTENSITIES IN THE HORIZONTAL PLANE OF FORWARD AND REAR POSITION LIGHTS. Refer to Advisory Circular 20-74.
674. § 27.1393 MINIMUM INTENSITIES IN ANY VERTICAL PLANE OF FORWARD AND REAR POSITION LIGHTS. Refer to Advisory Circular 20-74.
675. § 27.1395 MAXIMUM INTENSITIES IN OVERLAPPING BEAMS OF FORWARD AND REAR POSITION LIGHTS. Refer to Advisory Circular 20-74.
676. § 27.1397 (Amendment 27-6) COLOR SPECIFICATIONS. Refer to Advisory Circular 20-74.
677. § 27.1399 (Amendment 27-2) RIDING LIGHT.
a. Explanation. The riding light is an amphibious operation requirement. The function of this light is to make the rotorcraft visible at night to other vessels when the rotorcraft has landed on water. A very important point which should be remembered is that when a rotorcraft has landed on the water and is not in flight, it is considered a vessel in accordance with the United States Coast Guard (USCG) navigation rules 886 Par 669
7/30/97 АС 27-1A (Inland Navigation Rules Act of 1980). If water operations are contemplated, one should acquire the USCG Navigation Rules, COMDTINST M16672.2A, which are for sale from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.
b. Procedures. A white light should be installed in a position where it will show the maximum unbroken light for a horizontal arc of 360° around the rotorcraft. If possible, this light should not be obscured by sectors of more than 6°. The light should be installed to meet the malfunction requirements of § 27.1309(b). (Reference Paragraph 621 of this AC.) For the purpose of this light, the following definition found in the Inland Navigation Rules, 33 CFR 84.13, Color specification of lights, and 33 CFR 84.15, Intensity of lights, applies:
(1) The chromaticity of white lights shall conform to the following standards, which lie within the boundaries of the area of the diagram specified for each color by the International Commission on Illumination (CIE), in the "Colors of Light Signals which is incorporated by reference. It is Publication CIE No. 2.2 (TC-1.6), 1975, and is available from the Illumination Engineering Society, 345 East 47th Street, New York, NY 10017. It is also available for inspection at the Office of the Federal Register, Room 8401, 1100 L Street NW., Washington, D.C. 20408.
(2) The boundaries of the area for white are given by indicating the corner coordinates, which are as follows:
0.525 0.525 0.452 0.310 0.310 0.443
0.382 0.440 0.440 0.348 0.283 0.382 and 33 CFR 84.15 defines the required luminosity to be visible on a clear night for 2 nautical miles. The minimum luminosity of the light is given by the formula:
1=3.43 × 10°x Tx D x K° where: I is luminous intensity in candelas under service conditions, T is threshold factor 2 x 107 lux, D is range of visibility (luminous range) of the light in nautical miles, and K is atmospheric transmissivity. For prescribed lights the value of K shall be 0.8, corresponding to a meteorological visibility of approximately 13 nautical miles.
(3) Solving this formula indicates a minimum intensity of 4.3 candelas is required for this light.
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AC 27-1A 7/30/97.
NOTE: The FAR and the USCG navigation rules may be satisfied by an externally hung lights). One method of compliance would be to use USCG approved all-around lights which are of the appropriate luminosity and externally hung.
678. § 27,1401 (Amendment 27-10) ANTI-COLLISION LIGHT SYSTEM.
a. Certification for night operations requires an approved aviation red anti-collision light. Determination of the location and how many anti-collision lights are required to satisfy the regulations are functions of aircraft shape and the ability to obtain the required area coverage and light intensity. A detailed explanation of how to calculate the measured area coverage required by § 27.1401(b) is given in AC 20-30B.
An explanation of the methods used to measure and calculate the light intensity and color required by § 27.1401(e) are explained in AC 20-74.
b. The anti-collision lights) should be located to obtain the required coverage and to prevent cockpit reflections that would affect the crew's vision. The anti-collision lights are required to be red to reduce cockpit reflections and objectionable effect of rotor blade strobing. During the period of August 11, 1971, through February 4, 1976, white lights were permitted by the rules; however, white lights resulted in undesirable cockpit reflections at night and in close proximity to clouds. For these reasons, white lights are not considered to be satisfactory in all operating conditions.
Section 27.1401(b) was changed in 1976 to require a red anti-collision light. White lights have been approved for installation on rotorcraft when they were installed in addition to the required red lights, if an independent control for the white light was provided that allowed the pilot to eliminate any adverse cockpit reflections.
679.-688. RESERVED.
888 (thru 898) Par 677
SECTION 38. SAFETY EQUIPMENT
689. § 27.1411 (Amendment 27-11) GENERAL.
a. Explanation.
(1) This section contains requirements for the accessibility and stowage of required safety equipment. Compliance with this section should ensure that:
Locations for stowage of all required safety equipment have been provided.
(ii) Safety equipment is readily accessible to both crewmembers and passengers, as appropriate, during any reasonably probable emergency situation.
(III) Stowage locations for all required satety equipment will adequately protect such equipment from inadvertent damage during normal operations.
(iv) Safety equipment stowage provisions will protect the equipment from damage during emergency landings when subjected to the inertia loads specified in § 27.561.
(2) It is a frequent practice for the rotorcraft manufacturer to provide the substantiation for only those portions of the ditching requirements relating to aircraft flotation and ditching emergency exits. Completion of the ditching certification to include the safety equipment installation and stowage provisions is then left to the affected operator so that those aspects can best be adopted to the selected cabin interior. In such cases, the "Limitations" section of the Rotorcraft Flight Manual should identify the substantiations yet to be accomplished in order to justify the full ditching approval. The operator (or modifier) performing these final installations is then concerned directly with the details of this paragraph. Any aspects of the basic rotorcraft flotation and emergency exits approval that are not compatible with the modifier's proposed safety equipment provisions should be resolved between the type certificate holder and the modifier prior to FAA/AUTHORITY approval for ditching. (See Paragraphs 338a(9) and 691a(3).)
b. Procedures.
(1) A cockpit evaluation should be conducted to demonstrate that all required emergency safety equipment to be used by the crew will be readily accessible during any probable emergency situation. This evaluation should include, for example, emergency flotation equipment actuation devices, remote liferaft releases, hand fire extinguishers, and protective breathing equipment.
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(2) Stowage provisions for safety equipment shown to be compatible with the vehicle configuration presented for certification should be provided and identified so that:
(i) Equipment is readily accessible regardless of operational configuration.
(її) Stored equipment is free from inadvertent damage from passengers and handling.
Stored equipment is adequately restrained to withstand the inertia forces specified in § 27.561(b)(3) without sustaining damage.
(3) Liferaft stowage provisions should be sufficient to accommodate rafts for the maximum number of occupants for which certification for ditching is requested.
Liferafts stowed inside the rotorcraft should be located near the ditching emergency exits so that:
(A) Liferafts are readily accessible and deployment through ditching emergency exits by passengers and crew may be accomplished without unreasonable effort and training.
(B) Deployment of liferafts can be accomplished without damage
(l.e., punctures, tears, etc.).
Liferafts stowed outside of the rotorcraft should have-- (A) A readily accessible deployment device; and (B) A secondary method of deployment near the stowed area.
(iii) Rotorcraft fuselage attachments for the liferaft static lines required by § 27.1415(c) must be provided.
(A) Static line fuselage attachments should not be susceptible to damage when the rotorcraft is subjected to the maximum emergency ditching water entry loads established by § 27.801. (See Paragraph 338b(1).)
(B) Static line fuselage attachments should be structurally adequate to restrain a fully loaded raft of the maximum capacity required for ditching certification.
(C) Literafts that are remotely or automatically deployed must be attached to the rotorcraft by the required static line after deployment without further action from the crew or passengers.
900 Par 689
(4) Stowage provisions for signaling equipment required by § 27.1415 should be located near a designated ditching emergency exit.
(5) If stowage provisions for life preservers are included in an interior configuration, each life preserver when stowed must be within easy reach of each occupant while seated.
690. § 27.1413 (Amendment 27-25) SAFETY BELTS.
a. Explanation. Design and performance standards are contained in this section.
(1) Each safety belt must be equipped with metal-to-metal latches (Amdt. 27-15).
(2) Belts and belt anchors must sustain without failure ultimate loads as prescribed for each installation.
(3) Seats and berths are included.
(4) Litters, if installed, shall be included.
(5) TSO-C22, Safety Belts, contains acceptable aircraft belt standards. Also, TSO-C114, Torso Restraint Systems, dated March 27, 1987, contains acceptable aircraft standards for compliance to the standard per Amendment 27-25, dated November 13, 1989. In part, the belts shall have a 2-inch nominal width, shall be self-extinguishing per § 25.853(a), and may have a 1,500- or 3,000-pound rated strength.
b. Procedures.
(1) TSO-C22 or TSO-C114 approved seat belts or seat belt/harnesses should be used. The rated load shall not be exceeded. During an interior compliance inspection, the belt should be checked for label, rating, and metal-to-metal latches.
(2) The type design data shall contain an analysis or test results of belts and anchors proving compliance with the strength standards of this section. Fitting factors prescribed in § 27.785 shall be used.
(3) The use or application of the belts shall be proven in compliance with the standard. The belt rated strength shall not be exceeded by the ultimate load derived from § 27.561(b).
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(4) The rated strength of each unique belt may be stated in structural loads or design criteria report and the corresponding maximum ultimate design load listed for ease of comparison.
691. § 27.1415 (Amendment 27-11) DITCHING EQUIPMENT.
a. Explanation.
(1) Emergency flotation and signaling equipment is not required for all rotorcraft overwater operations. However, if such equipment is required by an operating rule
(e.g., § 135.167), the equipment supplied for compliance with the operating rule must meet the requirements of this section.
(2) Compliance with the provisions of § 27.801 for rotorcraft ditching requires compliance with the safety equipment stowage requirements and ditching equipment requirements of §§ 27.1411 and 27.1415, respectively.
Emergency flotation and signaling equipment installed to complete certification for ditching or required by any operating rule must be compatible with the basic rotorcraft configuration presented for ditching certification. It is satisfactory if operating equipment is not incorporated at the time of original type certification of the rotorcraft provided suitable information is included in the "Limitations" section of the Rotorcraft Flight Manual to identify the extent of ditching certification not yet completed.
(i¡) When the ditching equipment required by § 27.1415 is being installed by a person other than the applicant who provided the rotorcraft flotation system and ditching emergency exits, special care must be taken to avoid degrading the functioning of the aircraft devices and to make the ditching equipment compatible with them. (See Paragraphs 338a(9) and 689a(2).)
b. Procedures.
(1) Liferafts and life preservers used to show compliance with the ditching requirements must be of an approved type. Compliance with the requirements of TSO-C12 for liferafts and TSO-C13 for life preservers will satisfy regulatory requirements for approval of this equipment.
(i> Life Preservers.
(A) Life preservers should comply with the requirements of the applicable operating regulations (FAR Parts 91, 135, 121, etc.). For extended overwater operations, each life preserver is required by the operating rules to have an approved survivor locator light.
902 Par 690
7/30/97 АС 27-1А (B) Protective covers for life preservers should be compatible with the TSO requirements under which the basic life preserver was approved.
(ії) Liferafts.
(A) Liferafts are rated during their approval to the number of people that can be carried under normal conditions and the number that can be accommodated in an overload condition. Only the normal rating may be used in relationship to the number of occupants permitted to fly in the rotorcraft.
(B) Each liferaft released automatically or by the pilot must be attached to the rotorcraft by a line to secure the liferaft close to the rotorcraft for occupant egress. The line should be of adequate strength to restrain the liferaft under any reasonably probable sea state condition but must be designed to release before submerging the empty raft to which it is attached if the rotorcraft sinks.
(iii) Survival Equipment. Approved survival equipment if required by any operating rule must be attached to each liferaft. Provisions for the attachment and stowage of the appropriate survival equipment should be addressed during the ditching equipment segment of the basic ditching certification.
(2) Emergency signaling equipment required by any operating rule must be free from hazard in its operation. Required signaling equipment must be easily accessible to the passengers or crew and should be located near an emergency ditching exit or included in the survival equipment attached to one of the rafts.
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692. RESERVED.
Intentionally Left Blank 904 Par 692
693. § 27.1419 (Amendment 27-19) ICE PROTECTION.
a. Background.
(1) In March 1984, the FAA/AUTHORITY for the first time certificated a rotorcraft for flight into known icing conditions. Several other manufacturers are pursuing designs for icing flight capability.
(2) Most rotorcraft icing technology has been developed for military rotorcraft.
As of 1990, the only U.S. military rotorcraft equipped and approved for flight into icing conditions is the UH-60A (Blackhawk). The UH-60A is limited to supercooled cloud conditions where liquid water content (LWC) does not exceed 1.0 gm/m? and outside air temperature (OAT) is not below -20° C.
(3) Many rotorcraft operators have voiced a high priority on obtaining rotorcraft approved for operation in icing conditions.
(4) The icing characteristics envelope of FAR Part 25, Appendix C, has served as a satisfactory design criteria for fixed-wing operations for two decades. The envelope, as presented, extends to 22,000 feet with possible extension to 30,000 feet but does not present icing severity as a function of altitude. At the time the envelope was derived, it was assumed that all transport category airplanes would operate to at least 22,000 feet. For present state-of-the-art rotorcraft, this assumption is not valid.
As such, an altitude-limited icing envelope based on the same data used to derive the Part 25, Appendix C, and the Part 29, Appendix C, envelopes is presented as an alternate to the full-icing envelope.
b. Explanation.
(1) General.
The discussion in this paragraph pertains generally to certifications to the full-icing envelope of Part 29, Appendix C, within the altitude limitations of the rotorcraft or to the altitude-limited icing envelope based on a 10,000-foot pressure altitude limit. The actual icing envelope considered may be further restricted based on the actual pressure altitude envelope for which certification is requested. It envisions certification with full ice protection systems (rotor blades, windshields, engine inlets, stabilizer surfaces, etc.). With the exception of pilot controllable variables such as altitude and airspeed, limited certification (either in terms of icing envelope or protection capability) is not envisaged at this time due to the difficulty in forecasting the severity of icing conditions, relating the effects of the forecasted conditions to the type of aircraft, and the effects of reported icing among various types of aircraft, particularly between fixed- and rotary-wing aircraft. In addition, with a limited protection capability, viable escape options may not be operationally available if limitations are exceeded.
Par 693 905
АС 27-1A 7/30/97 (ї) The discussion in this paragraph, regarding rotor blade ice protection, is oriented primarily toward electrothermal rotor deicing systems, since these have the most widespread acceptance and projected use within the industry. Also, most of the testing and research into rotorcraft ice protection to date has been conducted with these types of systems. Research is continuing with other types of systems such as anti-icing fluid systems, and information will be added to address certification of these as necessary. It should also be noted that most of the rotorcraft icing experience accumulated to date has been on rotorcraft with symmetrical airfoil sections. The application of this experience to rotorcraft with asymmetrical airfoils should be carefully evaluated. Limited experience has been gained during development and qualification testing of the Army Blackhawk on asymmetrical airfoil icing characteristics. The most prominent difference appears to be a more rapid degradation of airfoil performance.
Rapidity of performance degradation is also dependent upon severity of the icing condition (primarily a function of liquid water content) and ice shape (primarily a function of OAT and median volumetric droplet diameter (MVD)).
The effects of ice can vary considerably from rotorcraft to rotorcraft.
Experience gained for a rotor system with an identical blade profile could provide valuable information but should be used cautiously when applied to another rotorcraft.
Assumptions cannot necessarily be made based on icing test results from another rotorcraft. Particular care should be exercised when drawing from fixed-wing icing experience as the widely different and varying conditions seen by the rotor blades make many comparisons with fixed-wing results invalid. Likewise, icing effects on rotor blades vary significantly from those on other parts of the rotorcraft. This is due to changing blade velocity as compared with the constant velocity of the remaining parts.
(2) Reference Material. Prior to commencement of efforts to design and certify a rotorcraft, the references listed in Paragraph d should be reviewed. FAA Technical Report ADS-4, Engineering Summary of Airframe Icing Technical Data, December 1963, although somewhat dated, is recommended for basic aircraft icing protection system design information.
(3) Objective. The objective of icing certification is to verify that throughout the approved envelope, the rotorcraft can operate safely in icing conditions expected to be encountered in service (i.e., Appendix C of Part 29 or the altitude-limited icing envelope presented herein). This will entail determining that no icing limitations exist or defining what the limitations are, as well as establishing the adequacy of the ice warning means (or system) and the ice protection system. A limiting condition may manifest itself in one of several areas such as handling qualities, performance, autorotation, asymmetric shedding from the rotors, visibility through the windshield, etc. Prior to flight tests in icing conditions, sufficient analyses should have been conducted to determine the design points for the particular item of the rotorcraft being analyzed (windshield, engine inlet, rotor blades, etc.). After the analyses are reviewed and found adequate, tests should be conducted to confirm that the analyses are valid and that the rotorcraft can operate safely in any supercooled cloud icing condition defined by Part 29, Appendix C, 906 Par 693
or the altitude-limited icing envelope. Sufficient flight tests should be conducted to assure adequate ice protection exists for the requested certification. References d(1) and (3) may be useful in determining the design points and extrapolation of test data to the desired design points.
(4) Planning. For best utilization of both the applicant's and the FAA/AUTHORITY's resources, the applicant should submit a certification plan at the start of the design and development effort. The certification plan should describe all efforts intended to lead to certification and should include the following basic information:
(i) Rotorcraft and systems description.
(Il) Ice protection systems description.
(iii) Certification checklist.
(iv) Description of analyses or tests planned to demonstrate compliance.
(v) Projected schedules of design, analyses, testing, and reporting efforts.
(vi) Methods of test - artificial vs. natural.
(vil) Methods of control of variables.
(vill) Data acquisition instrumentation.
(ix) Data reduction procedures.
(5) Environment.
(i> Definitions.
(A) Supercooled Clouds. Clouds containing water droplets (below 32° F) that have remained in the liquid state. Supercooled water droplets will freeze upon impact with another object. Water droplets have been observed in the liquid state at ambient temperatures as low as -60° F. The rate of ice accretion on an aircraft component is dependent upon many factors such as droplet size, cloud liquid water content, ambient temperature, and aircraft component size, shape, and velocity.
(B) Ice Crystal Clouds. Glaciated clouds existing usually at very cold temperatures where moisture has frozen to the solid or crystal state.
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