APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
transport category airplanes, as opposed to more complete scientific “characterizations” (Reference C1). A complete characterization may cover a wider range of parameters and values.
Traditionally, “Continuous Maximum” conditions are applied to airframe ice protection and “Intermittent Maximum” conditions are applied to engine ice protection (Reference C2).
Statistical analysis of data used to establish CAR part 4b, figures 4b-24a and 4b-25a and subsequent data shows that 99 percent of the data are in the temperature variant LWC envelopes (Reference C1).
CAR Amendment 4b-6, effective August 12, 1957, changed the icing envelopes to the current requirements and changed CAR § 4b.461, “Induction system deicing and anti-icing provisions.”
The preamble to the amendment states:
“There are included herein changes which extend the currently effective provisions governing intermittent maximum icing conditions so as to cover conditions which might be critical insofar as the turbine engine induction system is concerned. In this regard, the data are being extended in accordance with NACA Technical Note 2738 and involve a revision of figure 4b-25a to cover drop diameters as low as 15 microns and a revision of figure 4b-25c to cover distances down to 0.3 mile. The icing conditions prescribed in the currently effective regulations are applicable in the main to the airframe. The changes made in CAR § 4b.461 required the turbine powerplant to be subjected to the same icing conditions and required that the induction system be protected to prevent serious engine power loss. A similar requirement is incorporated with respect to certification of turbine engines by an amendment to part 13 which is being made concurrently with this amendment.”
The FAA recodified CAR Part 4b into 14 CFR part 25, effective January 1, 1965. After recodification, with minor editorial changes, the content of CAR § 4b.640, Ice protection, became 14 CFR § 25.1419; CAR § 4b.406, Propeller deicing provisions, became 14 CFR § 25.929; CAR § 4b.612(a)(5), Airspeed indicating systems, became 14 CFR § 25.1323(e); CAR § 4b.351(b)(1)(ii), Pilot compartment view, became 14 CFR § 25.773(b)(1)(ii). In 14 CFR part 25, the FAA changed the CAR § 4b.351 reference to the most severe icing conditions for which approval of the airplane is sought to reference the icing conditions specified in 14 CFR § 25.1419. CAR § 4b.461, Induction system deicing and anti-icing provisions, became 14 CFR § 25.1093.
Amendment 25-5, (30 FR 8261, June 29, 1965) effective July 29, 1965, changed 14 CFR § 25.1325(b) to require that each static port be designed and located so there is no change in the correlation between air pressure in the static pressure system and true ambient atmospheric static pressure when the airplane encounters the continuous and intermittent maximum icing conditions defined in 14 CFR part 25, Appendix C.
Amendment 25-11, (32 FR 6913, May 5, 1967) effective June 4, 1967, changed 14 CFR § 25.1585 to require that the Airplane Flight Manual (AFM) include information on using ice protection equipment.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
Amendment 25-23, (35 FR 5679, April 8, 1970) effective May 8, 1970, changed 14 CFR § 25.1419 to require that the effectiveness of the IPS and its components be shown by flight tests of the airplane or its components in measured natural icing conditions. Before this amendment, the FAA considered flight tests in natural icing conditions as one means of compliance but they were not mandatory. Amendment 25-23 also changed 14 CFR § 25.1309 to include extra requirements for certificating equipment, systems, and installations. The FAA changed the regulation to require a comprehensive systematic failure analysis, supported by suitable tests, to ensure that the safety objectives of the probability of occurrence decrease as the hazard of a failure increases.
Amendment 25-36, 39 FR 35432, October 1, 1974, (effective October 31, 1974), added the falling and blowing snow requirements to 14 CFR § 25.1093. The FAA changed requirements insuring acceptable induction system’s icing protection during ground operations icing conditions in 1977 and again in 1984 by Amendment 25-40, 42 FR 15034, March 17, 1977 and Amendment 25-57, 49 FR 6832, February 23, 1984, respectively.
Amendment 25-38, (41 FR 55468, December 20, 1976) effective December 20, 1976, added 14 CFR § 25.1403 to require a means for illuminating, or otherwise determining, ice accretion on the parts of the wings that are critical for ice buildup. The requirement is not applicable if the aircraft is prohibited from flight in icing conditions at night.
Amendment 25-43, (43 FR 10339, March 13, 1978) effective April 12, 1978, added 14 CFR § 25.1326 to require installing a pitot heat indication system on airplanes equipped with flight instrument pitot heating systems.
Amendment 25-46, (43 FR 50598, October 30, 1978) effective December 1, 1978, added 14 CFR § 25.1416 to require specific standards for pneumatic deicing boots.
Amendment 25-72, (55 FR 29785, July 20, 1990) effective July 20, 1990 transferred 14 CFR §§ 25.1416 to 25.1419 for clarification and editorial improvement and deleted 14 CFR § 25.1416.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
Table C-1. Chronology of 14 CFR Part 25 Icing Certification Requirements
DATE OF APPLICATION
FOR AIRPLANE TYPE
CERTIFICATION
CAR/TITLE STATUS ICING CERTIFICATION
REQUIREMENTS Before December 31, 1953 CAR Part 4 CAR § 4.5814 On or after December 31, 1953 CAR Part 4b (December 31, 1953, as amended through Amendment 4b-16) CAR §§ 4b.351(b)(ii), 4b.406, 4b.461, 4b.612(a)(5)4b.640 On or after August 25, 1955 Amendment 4b-2 CAR § 4b.640 amended to incorporate continuous maximum and intermittent maximum icing conditions which might be reasonably expected during normal operations On or after August 12, 1957 Amendment 4b-6 Changed the intermittent maximum icing conditions to include mean effective drop diameters as small as 15 ȝm (figure 4b-25a). Extended the liquid water content factor, F, to distances as short as 0.3 miles.
Amended CAR § .461 to require turbine powerplants and induction systems to be subjected to the continuous maximum and intermittent maximum icing conditions. (The preamble stated that the then current icing conditions requirements were mainly applicable to the airframe.)
On or after February 1, 1965 Recodification, 29 FR 18291, December 24, 1964 14 CFR § 25.1419 (originally CAR § 4b.640, with minor editorial changes), 14 CFR § 25.929 (originally § 4b.406), 14 CFR § 25.1323(e) (originally CAR § 4b.612(a)(5)), 14 CFR § 25.773(b)(1)(ii) (originally CAR § 4b.351(b)(1)(ii)), and 14 CFR § 25.1093 (originally CAR § 4b.161).
The CAR § 4b.351 reference to the most severe icing conditions for which approval of the airplane is sought, was changed to reference the icing conditions specified in 14 CFR § 25.1419.
On or after July 29, 1965 Amendment 25-5, 30 FR 8261, June 29, 1965 14 CFR § 25.1325(b) changed to require that the calibration of the static pressure source not change when the airplane encounters 14 CFR part 25, Appendix C icing conditions.
On or after June 4, 1967 Amendment 25-11, 32 FR 6913, May 5, 1967 14 CFR § 25.1585 changed to require that the AFM include information on use of the ice protection equipment.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
Table C-1. Chronology of 14 CFR Part 25 Icing Certification Requirements, Continued
DATE OF APPLICATION
FOR AIRPLANE TYPE
CERTIFICATION
CAR/TITLE STATUS ICING CERTIFICATION
REQUIREMENTS On or after May 8, 1970 Amendment 25-23, 35 FR 5679, April 8, 1970 14 CFR § 25.1419 changed to require that the effectiveness of the IPS and its components be shown by flight test of the airplane or its component in measured icing conditions. 14 CFR § 25.1309 changed to include added requirements for certificating equipment, systems, and installations.
On or after October 31, 1974 Amendment 25-36, 39 FR 35461, October 1, 1974 Falling and blowing snow added to 14 CFR § 25.1093.
On or after December 20, 1976 Amendment 25-38, 41 FR 55468, December 20, 1976 14 CFR § 25.1403 added to require a means to illuminate or otherwise determine ice accretion on parts of the wing that are critical for ice buildup, unless the airplane is limited from night operations.
April 12, 1978 Amendment 25-43, 43 FR 10339, March 13, 1978 14 CFR § 25.1326 added to require a pitot heat indication system, for airplanes with a heated pitot system.
December 1, 1978 Amendment 25-46, 43 FR 50598, October 30, 1978 14 CFR § 25.1416 added to require specific standards for pneumatic deicing boots.
July 20, 1990 Amendment 25-72, 55 FR 29785, July 20, 1990 14 CFR § 25.1403 transferred to 14 CFR § 25.1419 for clarification and editorial improvement. 14 CFR § 25.1416(c) changed to allow use of the “dark cockpit” concept (a warning when failure occurs rather than continual pilot monitoring).
C.2 NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES (14 CFR PART 23) The FAA certificated airplanes under CAR part 04 until 1945. CAR § 04.5814 required that if deicing boots were installed, they would have a positive means of deflation. There were no other references to an IPS in CAR part 04. When the FAA wrote separate regulations (CAR part 03) for normal category airplanes, they incorporated (without change) this requirement for positive means of deflating deicing boots in CAR § 03.541. In 1949, the FAA renumbered CAR § 03.541 as CAR § 3.712.
The FAA did not address ice protection again until they changed CAR part 03 in 1962 by Amendment 3-7. This amendment added CAR § 3.772 and CAR § 3.778. The amendment requires that the applicant provide information in the form of a placard in clear view to the pilot C-5
APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
specifying the types of operation and the meteorological conditions to which the airplane is limited by the equipment installed. This section places icing as a specific example of the meteorological conditions to be described. This change required a list of all installed equipment affecting the airplane operation limitations. The list also identified this equipment according to its operational function. This list of equipment later became known as the “Kind of Equipment List (KOEL).”
In 1964, the FAA recodified CAR part 03 (29 FR 17955, December 18, 1964) into 14 CFR part 23. After recodification, CAR § 3.712 became 14 CFR § 23.1419, and CAR §§ 3.772 and
3.778(h) became 14 CFR §§ 23.1559 and 23.1583(h), respectively. In 1965, Amendment 23-1 (30 FR 8261, June 29, 1965) changed 14 CFR § 23.1325 to include the effect of icing conditions on instruments that depend on static pressure. In 1969, Amendment 23-7 (34 FR 13095, August 13, 1969), added the requirement in 14 CFR § 23.1093(b) for turbine engines to operate in 14 CFR part 25, Appendix C icing conditions. These requirements apply to all airplanes regardless of whether they have an IPS approved under 14 CFR § 23.1419. Amendment 23-8 (35 FR 303, January 8, 1970), added 14 CFR § 23.1529, effective February 5, 1970. In the latter part of 1968, the FAA began an extensive review of the airworthiness standards of 14 CFR part 23. Because of this review, the FAA issued Amendment 23-14 (23 FR 31822, November 19, 1973), which made several substantive changes in the interest of safety to 14 CFR part 23. This amendment introduced a new 14 CFR § 23.929, which required engine installation ice protection and completely changed 14 CFR § 23.1419 to establish standards for IPSs. It also introduced a new 14 CFR § 23.1309, which established reliability and noninterference requirements for installed equipment and systems. These three sections are directly related (as defined in 14 CFR § 21.101) to IPS certification because of the increased reliance on this system when operating the airplane in an icing environment.
Amendment 23-26 (45 FR 60154, September 11, 1980), changed 14 CFR § 23.1529 and added requirements for preparation of Instructions for Continued Airworthiness in 14 CFR part 23, Appendix G, effective October 14, 1980.
The FAA unintentionally omitted specific standards for pneumatic deicing boots, that were in the former 14 CFR § 23.1419, when they adopted Amendment 23-14 (23 FR 31822, November 19, 1973). The FAA realized that a specific standard for pneumatic deicing boot systems was needed and in Amendment 23-23 (43 FR 50593, issued October 30, 1978) we added 14 CFR § 23.1416(c), pneumatic deicing boot system. Current certification requirements are limited to those icing conditions produced by clouds that contain supercooled water drops as defined by 14 CFR part 25, Appendix C. The certification requirements do not require design or proof of capability to operate in freezing rain and drizzle, snow, or mixed conditions.
In 1974, the FAA added engine operation requirements for falling and blowing snow to 14 CFR § 23.1093 by Amendments 23-15 (39 FR 35460, October 1, 1974). Amendment 23-18 (42 FR 15041, March 17, 1977) and Amendment 23-29 (49 FR 6847, February 23, 1984) changed requirements insuring acceptable induction system’s icing protection during ground operation icing conditions.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
When the FAA adopted Amendment 23-41 (55 FR 43309, October 26, 1990), 14 CFR § 23.1309 kept the existing reliability requirements adopted by Amendment 23-14, (38 FR 31822, dated November 19, 1972), for airplane equipment, systems, and installations that are not complex and do not perform critical functions. If the applicant finds it necessary or desirable to include complex systems or systems that perform critical functions, or both, then 14 CFR § 23.1309 as amended by Amendment 23-41, provides more requirements for identifying and certificating such equipment, systems, and installations. This amendment allowed the approval of more advanced systems capable of performing critical functions.
When Amendment 23-42 (56 FR 354, dated January 3, 1991) became effective on February 4, 1991, it added 14 CFR § 23.1323(e) to require a heated pitot tube, or an equivalent means of preventing malfunction due to icing. The FAA also took this opportunity to clarify why a heated pitot tube must be part of the system approval for flight in icing conditions. Also included by this amendment is 14 CFR § 23.1325(g) allowing airplanes that are forbidden to fly in instrument meteorological conditions (IMC) to be certificated without an alternate static air source.
Amendment 23-43 (58 FR 18973, dated April 9, 1993), became effective May 10, 1993, resulting in 14 CFR § 23.905(e) requiring that ice shed from the airplane not damage a pusher propeller. The FAA added 14 CFR §§ 23.1093(a)(5) and (6) to address aircraft with fuel injected engines. The FAA stated the ice protection requirements for fuel injection system designs with and without metering components on which impact ice may accumulate in 14 CFR § 23.1093(a)(6). Also, the FAA added 14 CFR § 23.1307(c) to require the airplane type design to include all the equipment necessary for operation according to the limitations required by 14 CFR § 23.1559. The FAA also changed 14 CFR § 23.1419 to continue the current minimum ice protection requirements that have been found necessary for safe operation in icing conditions.
Lastly, this revision provides specific test requirements, to clarify the requirements for information that must be provided to the pilot, and to allow approval of equivalent components that have been previously tested and approved, and that have shown satisfactory service if the installations are similar.
Amendment 23-45, 58 FR 42165 (dated August 6, 1993), became effective September 7, 1993, and added the following sections:
(1) 14 CFR § 23.773(b) to provide requirements for the pilot compartment view to address the environment expected in all the operations sought for certification;
(2) 14 CFR § 23.775(f) to clarify the criteria for determining the cleared windshield area that is necessary to ensure safe operation in icing conditions;
(3) 14 CFR § 23.775(g) to require that a single failure of a transparency heating system not adversely affect the integrity of the airplane cabin nor increase the danger of fire; and C-7
APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
(4) 14 CFR § 23.1525 was changed to require establishing and including the kinds of operations authorized in the Airplane Flight Manual (AFM) as specified by 14 CFR § 23.1583(h).
Amendment 23-48 (61 FR 5168, dated February 9, 1996), became effective March 11, 1996, by revising 14 CFR § 23.1325(g) to exempt airplanes that are forbidden to fly in instrument meteorological or icing conditions from the requirements of 14 CFR § 23.1325(b)(3). Also, the FAA added 14 CFR § 23.1326 to require installing a pitot tube heat-indicating system on those airplanes required to have heated pitot tube. Airplanes that are approved for instrument flight, or for flight in icing conditions, would need to have a heated pitot tube and a heated pitot tube indicator by this amendment.
Because of the large fleet of small airplanes that have been certificated under the requirements of earlier regulations, the applicability of later regulations to previously approved ice protection provisions may vary as those aircraft are modified.
With Amendment 23-14 (38 FR 31822, dated November 19, 1973), 14 CFR §§ 23.929, 23.1309, and 23.1419 applied to the icing certification of all 14 CFR part 23 airplanes regardless of the original certification basis for the basic airplane. The application may be limited to the equipment used for ice protection on airplanes certificated according to CAR part 3 and 14 CFR part 23 through Amendment 23-13. When some systems are used as part of that airplane’s icing approval, the previously approved systems on the airplane may need to be modified to improve their reliability.
When the FAA adopted Amendment 23-43 (58 FR 18973, dated April 9, 1993), they changed 14 CFR § 23.1419 to continue the current minimum ice protection requirements found necessary for safe operation in icing conditions. The amendment also provides specific test requirements and clarifies the requirements for information that must be provided to the pilot. The amendment also allows approval of equivalent components which were previously tested and approved, and which showed satisfactory service (if the installations are similar).
Besides the previously mentioned requirements (14 CFR §§ 23.929, 23.1309, and 23.1419), table C-2 lists the sections that should be applied depending on the IPS design and the original certification basis of the airplane. Many of the requirements listed in table C-2 also apply, even without approval for flight into known icing.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
Table C-2. Chronology of 14 CFR Part 23 Icing Certification Requirements
DATE OF APPLICATION
FOR AIRPLANE TYPE
CERTIFICATION
CAR/TITLE STATUS ICING CERTIFICATION
REQUIREMENTS Before February 1, 1965 Part 3 of the CAR, (May 15, 1956, as amended through Amendment 3-8) §§ 3.85(a) and (c), 3.85a(a) and (c),
3.382, 3.383, 3.446, 3.575, (including note following (b)), 3.652, 3.652-1,
3.665, 3.666, 3.681, 3.682, 3.685,
3.686, 3.687, 3.690, 3.691, 3.692,
3.712, 3.725, 3.758, 3.770, 3.772,
3.777, 3.778, and 3.779 On or after February 1, 1965 Recodification, 29 FR 17955, December 18, 1964 and 30 FR 258, January 9, 1965.
§§ 23.65, 23.75, 23.77, 23.773, 23.775,
23.1301, 23.1351, 23.1357, 23.1437,
23.1541, 23.1559(b), 23.1583(h),
23.1585, and 23.1419 (boot requirement before Amendment 23-14) On or after July 29, 1965 Amendment 23-1, 30 FR 8261, June 29, 1965 Add § 23.1325 to the above part 23 requirements.
On or after September 14, 1969 Amendment 23-7, 34 FR 13095, August 13, 1969 Added the requirement in 14 CFR § 23.1093 for turbine engines to operate in 14 CFR part 25, Appendix C icing conditions.
On or after February 5, 1970 Amendment 23-8, 35 FR 303, January 8, 1970 Add § 23.1529 to the above part 23 requirements.
On or after December 20, 1973 Amendment 23-14, 33 FR 31822, November 19, 1973.
Add §§ 23.853(d), 23.929, 23.903(c), and 23.1309 to the above part 23 requirements. Amended § 23.1419 to require test and analysis to show safe operation in 14 CFR part 25, Appendix C icing conditions On or after October 31, 1974 Amendment 23-15, 39 FR 35460, October 1, 1974 Falling and blowing snow and ground ice fog requirements added to 14 CFR § 23.1093. Amendments 23-18, 42 FR 15041, March 17, 1977 and Amendment 23-29, 49 FR 6847, February 23, 1984, respectively, changed the ground ice fog requirements.
On September 1, 1977 Amendment 23-20, 42 FR 36969, July 18, 1977 Add §§ 23.1327 and 23.1547 to the above part 23 requirements.
On or after December 1, 1978 Amendment 23-23, 43 FR 50593, October 30, 1978 Add §§ 23.863, and 23.1416 (instead of the boot requirement of § 23.1419 before Amendment 23-14) to the above part 23 requirements.
On or after October 14, 1980 Amendment 23-26, 45 FR 60154, September 11, 1980 Changed 14 CFR § 23.1529 and added requirements for preparation of Instructions for Continued Airworthiness as 14 CFR part 23, Appendix G.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
DATE OF APPLICATION
FOR AIRPLANE TYPE
CERTIFICATION
CAR/TITLE STATUS ICING CERTIFICATION
REQUIREMENTS On or after February 17, 1987 Amendment 23-34, 52 FR 1833, January 15, 1987 For commuter category airplanes, add §§ 23.67(e)(2), 23.67(e)(3), 23.997(e), and 23.1199(b) to the above part 23 requirements.
On or after February 4, 1991 Amendment 23-42, 56 FR 354, January 3, 1991 Add §§ 23.1323(e) and 23.1325(g) to the above part 23 requirements.
On or after May 10, 1993 Amendment 23-43, 58 FR 18973, April 9, 1993 Add §§ 23.905(e), 23.1093(a)(6), and
23.1307(c) to the above part 23 requirements. Amended § 23.1419 to require compliance with Subpart B regulations in icing.
On or after September 7, 1993 Amendment 23-45, 58 FR 42165, August 6, 1993 Add §§ 23.773(b), 23.775(f),
23.775(g), and 23.1525 to the above part 23 requirements.
On or after February 9, 1996 Amendment 23-49, 61 FR 5168, February 9, 1996 Changed 14 CFR § 23.1325(g) and added requirements for pitot heatindication system as 14 CFR § 23.1326.
C.3 AIRCRAFT ENGINES (14 CFR PART 33).
Until the late 1950s, the only icing requirements for engines were carburetor icing requirements that were applied to reciprocating engines and then to induction system icing. During the late 1950s, with the introduction of turbine engines, the FAA introduced CARs for turbine engines and fuel and induction systems icing. Amendment 4b-6 (dated August 12, 1957), changed CAR § 4b.461, “Induction system deicing and anti-icing provisions.” The preamble to the amendment states:
“There are included herein changes which extend the currently effective provisions governing intermittent maximum icing conditions so as to cover conditions which might be critical insofar as the turbine engine induction system is concerned. In this regard, the data are being extended in accordance with NACA Technical Note 2738 and involve a revision of figure 4b-25a to cover drop diameters as small as 15 microns and a revision of figure 4b-25c to cover distances down to 0.3 miles. The changes made in section 4b.461 required that the turbine powerplant be subjected to the same icing conditions as the airframe and that the induction system be protected to prevent serious engine power loss.
A similar requirement is incorporated with respect to certification of turbine engines by an amendment to part 13 which is being made concurrently with this amendment.”
During 1965, the FAA codified Federal Aviation Regulations (FAR) from the CAR. They placed turbine engines icing requirements in 14 CFR 33.66, 33.67, and 33.89. They introduced 14 CFR § 33.68 in Amendment 33-6, 39 FR 35463, October 1, 1974. The extracted requirements from 33.67, fuel and induction system requirements. 14 CFR § 33.68 is entitled C-10
APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
“induction system icing,” however turbine engines do not typically include the “induction system” (for example, inlet, or other air delivery ducting) in the engine Type Design. Therefore, turbine engine 14 CFR 33.68 icing issues are mainly “internal” to the engine (including the spinner, fan blades, compressor stators and blades, etc.) and typically reside in the category of unprotected surfaces. Table C-3 summarizes the chronology of engine ice protection requirements.
Table C-3. Chronology of 14 CFR Part 33 Engine Icing Certification Requirements
DATE OF APPLICATION
FOR ENGINE TYPE
CERTIFICATION
CAR/TITLE STATUS ICING CERTIFICATION
REQUIREMENTS Before August 12, 1957 Part 13 of the CAR, (May 15, 1956, as amended through Amendment 13-1) §§ 13.110(b), 13.155 (Reciprocating engines and fuel induction systems only) On or after August 12, 1957 Part 13 of the CAR, (May 15, 1956, as amended through Amendment 13-5) §§ 13.110(b), 13.155 (Recip.
Engines) §§ 13.210(b), (c) and (e), 13.255 (Turbine Engines) On or after February 1, 1965 Recodification, 29 FR 7453, June 10, 1964 §§ 33.35, 33.51 (Recip. Engines) §§ 33.66, 33.67, 33.89 (Turbine Engines) On or after October 1, 1974 Amendment 33-6, 39 FR 35463, October 1, 1974 Replaced § 33.67 with § 33.68 and added § 33.77 On or after March 26, 1984 Amendment 33-10, 49 FR 6851, February 23, 1984 Changed § 33.77 to require ice slab size based on a two-minute delayed engine IPS activation, rather than 30 seconds.
C.4 ROTORCRAFT (14 CFR PARTS 27 AND 29).
In CAR part 6, the only icing requirement for Normal Category rotorcraft concerned carburetor preheat, CAR § 6.462 “Induction system deicing and anti-icing provisions.” This requirement was carried over to 14 CFR § 27.1093. The FAA did not address the approval of other ice protection provisions for a type of operation in icing conditions, CAR § 6.718, before the 1964 regulation recodification.
CAR § 7.392, the earlier Transport Categories Rotorcraft airworthiness requirements, addressed approval of ice protection provisions for icing conditions that apply to the design’s operating limitations. This CAR part 7 requirement was carried over into 14 CFR § 29.877 and now as 14 CFR § 29.1419. CAR part 7 addressed pilot compartment vision, requiring “sufficiently extensive view to permit safe operation” in the most severe icing conditions in which operation of the rotorcraft is approved. The pilot compartment requirement was carried over into 14 CFR § 29.773. Engine air induction and engine air induction system screens ice protection provisions, CAR §§ 7.461 and 7.464, were carried over into 14 CFR §§ 29.1093 and 29.1105.
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APPENDIX C. BACKGROUND OF ICE PROTECTION REGULATORY
DEVELOPMENT (CONTINUED)
C.5 REFERENCES.
C1. “Recommended Values of Meteorological Factors to be Considered in the Design of Aircraft Ice-Prevention Equipment,” NACA Technical Note 1855 (1949), NASA/Ames Research Center, Moffett Field, California 94035.
C2. “Review of Icing Criteria,” Lewis, William, Aircraft Ice Protection, Report of Symposium, April 28-30, 1969.
C-12
APPENIDX D. COMPONENT ICE PROTECTION SYSTEM DESIGN AND
CERTIFICATION PROCESS FLOWCHARTS Figure D-1 shows the flow of a typical inflight icing certification program. Figures D-2 through D-7 provide typical program flowcharts for the design and certification of critical surfaces, engine, propeller, airframe components, and probes ice protection. These program flowcharts are general in nature and may not be applicable to all icing certification programs. Applicants should assess their aircraft for design features that warrant added considerations to ensure safe flight in icing conditions.
D-1