APPENDIX A. RELATED REGULATIONS AND DOCUMENTS (CONTINUED) Table A-1. Related 14 CFR Parts 23, 25, 27, an d 29 Regulations (Continued) Subpart Part 23 Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes Part 25 - Airworthiness Standards: Transport Category Airplanes Part 27 – Airworthiness Standards: Normal Category Rotorcraft Part 29 – Airworthiness Standards: Transport Category Rotorcraft E-Powerplant § 23.901(d)(2), Installation § 23.903, Engines § 23.905(e), Propellers § 23.929, Engine installation ice protection § 23.939, Powerplant operating characteristics § 23.951(c), Fuel System, General § 23.975, Fuel tank vents and carburetor vapor vents § 23.997(e), Fuel strainer or filter § 23.1013(d), Oil tanks, vent § 23.1041, General - cooling § 23.1093, Induction system icing protection § 23.1095, Carburetor deicing fluid flow rate § 23.1097, Carburetor deicing fluid system capacity § 23.1099, Carburetor deicing fluid system detail design § 23.1101, Carburetor air preheat design § 23.1105, Induction system screens § 23.1157, Carburetor air temperature controls § 23.1189, Shutoff means § 23.1199(b), Extinguishing agent containers § 25.901(c), Installation § 25.903, Engines § 25.929, Propeller deicing § 25.939, Turbine engine operating characteristics § 25.941, Inlet, engine and exhaust compatibility § 25.951(c), Fuel System, General § 25.975, Fuel tank vents and carburetor vapor vents § 25.981, Fuel tank ignition prevention § 25.1013(d), Oil tanks, vent § 25.1041, General - cooling § 25.1093, Induction system icing protection § 25.1101, Carburetor air preheat design § 25.1105, Induction system screens § 25.1157, Carburetor air temperature controls § 25.1189, Shutoff means § 25.1199(b), Extinguishing agent containers § 27.939, Turbine engine operating characteristics § 27.951(c), Fuel System, General § 27.975, Fuel Tank Vents § 27.1041, General - cooling § 27.1093, Induction system icing protection § 29.901(c), Installation § 29.939, Turbine engine operating characteristics § 29.951(c), Fuel Systems, General § 29.975, Fuel Tank Vents and Carburetor Vapor Vents § 29.1013(d), Oil tanks, vent § 29.1041, General - cooling § 29.1093, Induction system icing protection § 29.1101, Carburetor air preheater design § 27.1105, Induction system screens § 29.1157, Carburetor air temperature controls § 29.1189(a), Shutoff means § 29.1199(b), Extinguishing agent containers A-4
APPENDIX A. RELATED REGULATIONS AND DOCUMENTS (CONTINUED) Table A-1. Related 14 CFR Parts 23, 25, 27, an d 29 Regulations (Continued) Subpart Part 23 Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes Part 25 - Airworthiness Standards: Transport Category Airplanes Part 27 – Airworthiness Standards: Normal Category Rotorcraft Part 29 – Airworthiness Standards: Transport Category Rotorcraft F-Equipment § 23.1301, Function and installations § 23.1305(c)(7), Powerplant instruments § 23.1307, Miscellaneous equipment § 23.1309, Equipment, systems, and installations § 23.1323(d), Airspeed indicating system § 23.1325, Static pressure system § 23.1326, Pitot heat indication systems § 23.1327, Magnetic direction indicator § 23.1351, General § 23.1357, Circuit protective devices § 23.1416, Pneumatic de-ice boot system § 23.1419, Ice protection § 25.1301, Function and installation § 25.1305(c)(5), Powerplant instruments § 25.1307(c), Miscellaneous equipment § 25.1309, Equipment, systems, and installations § 25.1323(e), Airspeed indicating system § 25.1325(b), Static pressure systems § 25.1326, Pitot heat indication system § 25.1327, Magnetic direction indicator § 25.1351, General § 25.1353, Electrical equipment and installations § 25.1357, Circuit protective devices § 25.1403, Wing icing detection lights § 25.1419, Ice protection § 25.1455, Draining of fluids subject to freezing § 27.1301, Function and installation § 27.1305(p), Powerplant instrumentation § 27.1307(d), Miscellaneous equipment § 27.1309, Equipment, systems, and installation § 27.1325(b), Static pressure systems § 27.1327, Magnetic direction indicator § 27.1351, General § 27.1419, Ice protection § 29.1301, Function and installation § 29.1305(a)(17), Powerplant instruments § 29.1309, Equipment, systems, and installations § 29.1323(f), Airspeed indicating systems § 29.1325(c), Static pressure and pressure altimeter systems § 29.1351, General § 29.1353, Electrical equipment and installations § 29.1419, Ice protection G-Operating Limitations and Information § 23.1525, Kinds of operations § 23.1529, Instructions for Continued Airworthiness § 23.1559(b), Operating limitations placard § 23.1583(h), Operating limitations § 23.1585, Operating procedures § 25.1525, Kinds of operations § 25.1529, Instructions for Continued Airworthiness § 25.1583, Operating limitations § 25.1585(a)(6), Operating procedures § 27.1525, Kinds of operation § 27.1529, Instructions for Continued Airworthiness § 27.1559, Limitations placard § 27.1583, Operating limitations § 27.1585, Operating procedures § 29.1525, Kinds of operations § 29.1529, Instructions for Continued Airworthiness § 29.1559, Limitations placard § 29.1583, Operating limitations § 29.1585, Operating procedures Other Appendix C of Part 25 Appendix C Appendix C of Part 29 Appendix C A-5
APPENDIX A. RELATED REGULATIONS AND DOCUMENTS (CONTINUED) Table A-2. Related 14 CFR Part 33 - Airworthiness Standards: Aircraft Engines Regulations Subpart A - General § 33.4 Instructions for Continued Airworthiness D - Design Construction § 33.35(b) Fuel and induction system E - Design and Construction; Turbine Aircraft Engines § 33.65 § 33.66 § 33.67(b)(4)(ii) § 33.68 § 33.77 § 33.89(b) Foreign object ingestion–ice Bleed air system Fuel system Induction system icing Foreign object ingestion - ice Operational test Table A-3. Related 14 CFR Part 35 - Airworthiness Standards: Propellers Subpart A - General § 35.3 § 35.4 Instruction manual for installing and operating the propeller Instructions for Continued Airworthiness Table A-4. Related Operating Rules Subchapter 14 CFR Part Subpart Section F – Air Traffic and General Operating Rules 91, General Operating and Flight Rules F – Large and Turbine- Powered Multiengine Airplanes § 91.527 Operating in icing conditions G – Air Carriers and Operators for Compensation or Hire: Certification and Operation 121, Operating Requirements;
Domestic, Flag, and Supplemental Operations U – Dispatching and Flight Release Rules § 121.629 Operating in icing conditions 125, Certification and Operations:
Airplanes Having a Seating Capacity of 20 or More Passengers or a Maximum Payload Capacity of 6,000 Pounds or More; and Rules Governing Person On Board Such Aircraft F – Instrument and Equipment Requirements § 125.221 Icing conditions:
Operating limitations 135, Operating Requirements:
Commuter and On Demand Operations and Rules Governing Person On Board Such Aircraft D – VFR/IFR Operating Limitations and Weather Requirements § 135.227 Icing conditions:
Operating limitations 14 CFR SFAR No. 88 Fuel Tank System Fault Tolerance Evaluation Requirements A.2 ADVISORY CIRCULARS.
Except for ACs 25-7A and 23-8B, you may get the ACs listed below on the FAA web site or from the U.S. Department of Transportation at the following address: Subsequent Distribution Office, SVC-121.23, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785.
AC 25-7A is available from the Superintendent of Documents, U.S. Government Printing Office, A-6
APPENDIX A. RELATED REGULATIONS AND DOCUMENTS (CONTINUED) Washington D.C. (stock number 050-007-01214-4, $33.00). You may buy copies of AC 23-8B from the Superintendent of Documents, P.O. Box 371954, Pittsburgh, PA 15250-7954. Make check or money order payable to the Superintendent of Documents.
AC 20-73 Aircraft Ice Protection AC 20-115B Radio Technical Commission for Aeronautics, Inc. (RTCA) Document RTCA/DO-178B AC 20-117A Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Aircraft Icing.
AC 20-147 Turbojet, Turboprop, and Turbofan Engine Induction System Icing AC 21-16D RTCA Document DO- 160D AC 21-40 Application Guide for Obtaining a Supplemental Type Certification AC 21.101-1 Establishing the Certification Basis of Changed Aeronautical Products AC 23-8B Flight Test Guide for Certification of Part 23 Airplanes AC 23-16A Powerplant Guide for Certification of Part 23 Airplanes and Airships AC 23-17A Systems And Equipment Guide For Certification Of Part 23 Airplanes AC 23.143-1 Ice Contaminated Tailplane Stall AC 23.629-1A Means of Compliance with Section 23.629, Flutter AC 23.1309-1C Equipment, Systems, and Installation in Part 23 Airplanes AC 23.1419-2C Certification of Part 23 Airplanes for Flight in Icing Conditions AC 25-7A Change 1 Flight Test Guide for Certification of Transport Category Airplanes AC 25-11 Transport Category Airplane Electronic Display Systems AC 25-22 Certification of Transport Airplane Mechanical Systems AC 25.629-1A Flutter Substantiation of Transport Category Airplanes AC 25.1309-1A System Design Analysis AC 25.1419-1A Certification of Transport Category Airplanes for Flight in Icing Conditions AC 27-1B Certification of Normal Category Rotorcraft A-7
APPENDIX A. RELATED REGULATIONS AND DOCUMENTS (CONTINUED) AC 29-2C Certification of Transport Category Rotorcraft AC 33-2B Aircraft Engine Type Certification Handbook AC 120-42A Extended Range Operation with Twin-Engine Airplanes (ETOPS) AC 120-58 Pilot Guide for Large Aircraft Ground Icing AC 120-60 Ground Deicing and Anti-Icing Program AC 135-16 Ground Deicing & Anti-icing Training & Checking AC 135-17 Pilot Guide - Small Aircraft Ground Deicing (pocket) A.3 RELATED READING MATERIAL.
(1) FAA Technical Report DOT/FAA/CT-88/8-1, “Aircraft Icing Handbook,” published March 1991, updated September 1993, includes reference material on ground and airborne icing facilities, simulation procedures, and analytical techniques. This document represents all types and classes of aircraft. The FAA intends it to be a working tool for the designer and analyst of IPSs. The FAA William J. Hughes Technical Center continues with the transfer of material from the Aircraft Icing Handbook (AIHB) to the Electronic Aircraft Icing Handbook (EAIHB) web site:
http://aar400.tc.faa.gov/Programs/FlightSafety/icing/eaihbk.htm
(2) FAA Technical Report ADS-4, “Engineering Summary of Airframe Icing Technical Data,” and Report No. FAA-RD-77-76, “Engineering Summary of Powerplant Icing Technical Data,” provides technical information on airframe and engine icing conditions. They also provide methods of detecting, preventing, and removing ice accretion on airframes and engines in flight. Although most of the information in ADS-4 and FAA-RD-77-76 is still valid, some is outdated. More usable information is now available through recent research and experience and is included in the Aircraft Icing Handbook referenced in paragraph (1) above.
NOTE: You may get copies of the FAA technical reports listed above from: the National Technical Information Service (NTIS), Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161.
(3) NACA Technical Note 1855 (1949), “Recommended Values of Meteorological Factors To Be Considered in the Design of Aircraft Ice-Prevention Equipment,” NASA Ames Research Center, Moffett Field, California 94035.
(4) NACA Technical Note 2738 (1952), “A Probability Analysis of the Meteorological Factors Conducive to Aircraft Icing in the United States,” NASA Glenn Research Center, Cleveland, Ohio 44135.
A-8
APPENDIX A. RELATED REGULATIONS AND DOCUMENTS (CONTINUED)
(5) RTCA/DO160D, “Environmental Conditions and Test Procedures for Airborne Equipment,” dated July 29, 1997.
(6) RTCA/DO-178B, “Software Considerations in Airborne Systems and Equipment Certification,” published December 1, 1992, provides an acceptable means of compliance for software used in airborne systems and equipment.
(7) RTCA/DO-254, “Design Assurance Guidance for Airborne Electronic Hardware.”
NOTE: You may request the RTCA documents from: RTCA Inc., 1140 Connecticut Avenue NW, Suite 1020, Washington, D.C. 20036.
(8) SAE AIR5504, “Aircraft Inflight Icing Terminology,” (September 1, 2002).
(9) SAE AIR1168/4, “Ice, Rain, Fog, and Frost Protection.”
(10) SAE ARP4087, “Wing Inspection Lights – Design Criteria.”
(11) SAE ARP4754, “Certification Considerations for Highly-Integrated or Complex Aircraft Systems.”
(12) SAE ARP4761, “Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment.”
(13) SAE ARP5903, “Droplet Impingement and Ice Accretion Computer Codes,” (October 16, 2003).
(14) SAE ARP5904, “Airborne Icing Tankers,” (October 21, 2002).
(15) SAE ARP5905, “Calibration and Acceptance of Icing Wind Tunnels,” (October 18, 2003).
NOTE: You may get SAE Aerospace Recommended Practices and Aerospace Information Reports from: SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.
A-9 (and A-10)
APPENIDX B. NOMENCLATURE B.1 TERMS.
Anti-icing: Preventing ice formation or buildup on a protection surface. This occurs by either evaporating the impinging water or by allowing it to run back and off the surface or to run back and freeze on non-critical areas.
Appendix C: The 14 CFR parts 25, Appendix C and 29, Appendix C icing envelopes for continuous maximum and intermittent maximum icing conditions.
Appendix C icing conditions: 14 CFR parts 25, Appendix C and 29, Appendix C certification icing condition standard for approving ice protection provisions on aircraft. The conditions are specified by altitude, temperature, liquid water content (LWC), representative drop size (mean effective diameter (MED)), and cloud horizontal extent.
NOTE: In Appendix C, the term “mean effective diameter” refers to what is now called the “median volume diameter (MVD).” The MED of Appendix C was determined by using rotating multi-cylinders and assuming a Langmuir distribution.
Artificial ice: A structure formed from material other than frozen water, but intended to represent an ice accretion. See “simulated ice shapes.”
Clear ice: See “glaze ice.”
Collateral icing: Ice accretions that occur on aircraft surfaces other than those typically considered when aircraft certification tests use simulated ice shapes. Examples are ice feathers that accumulate on fuselage, nacelle, nacelle pylons, empennage, antennas, and wing surfaces.
Collection efficiency: See “water catch efficiency.”
Computational fluid dynamics (CFD): The science of solving discretized equations for fluid flow on a computer.
Computed ice: An ice shape generated by CFD codes or other analytical means.
Critical ice shape: The aircraft surface ice shape formed within required icing conditions. It results in the most adverse effects for specific flight safety requirements. For an aircraft surface, the critical ice shape may differ for different requirements (for example, stall speed, climb, aircraft controllability, control surface movement, control forces, air data system performance, dynamic pressure probes for control force “feel” adjustment, ingestion and structural damage from shed-ice, engine thrust, engine control, and aeroelastic stability).
Critical aircraft ice shape configuration: The ice-contaminated aircraft configuration that results in the most adverse effects for specific flight safety requirements.
B-1
APPENDIX B. NOMENCLATURE (CONTINUED)
Critical surface: A surface whose integrity affects safe aircraft takeoff, flight, and landing. A surface that accretes ice and affects safe aircraft takeoff, flight, and landing is a critical surface for inflight icing.
Deice or deicing: The periodic shedding or removal of ice buildups from a surface. This occurs by destroying the bond between the ice and the protection surface.
Empirical validation/evaluation: Validation or evaluation of analytical results by experimental data.
Euler equations: The title given to equations, developed by L. Euler, for calculating the flow of a frictionless, nonviscous fluid. The equations address compressibility of a fluid. They do not address flowfield discontinuities, such as those from shocks. Flow field rotation can be computed. The Euler equations of fluid flow can be integrated throughout a finite region to determine the dynamic equilibrium of a finite volume of particles, applying Newton’s second law (momentum) to the group of fluid particles. This flowfield solution is called Eulerian, compared with a more complex flowfield solution that tracks each fluid particle (the Lagrangian approach). Traditionally, flow field analyses performed using the Euler equations are considered to be between analyses performed using the potential flow and the Navier-Stokes equations, in complexity and sophistication.
Eulerian: See “Euler Equations.”
Extended range operations with twin-engine airplanes (ETOPS): Operation of twin-engine airplanes for extended periods beyond alternate airports (AC 120-42A).
Failure ice: Aircraft ice accretion following failure of the ice protection system (IPS), or its components.
Finite wing: A wing having finite span. Vortices, which are shed at the wing tips, affect finite wings. Considerations such as spanwise airflow are more difficult to analyze theoretically.
Forecast icing conditions: Meteorological conditions that an FAA-approved weather provider expects to be conducive to forming ice on aircraft in flight.
Freezing drizzle (FZDZ): Precipitation at ground level or aloft in the form of liquid water drops. The drizzle drop diameters are less than 0.5 mm and greater than 0.05 mm. Freezing drizzle exists at air temperatures less than 0qC and colder (supercooled), remains in liquid form, and freezes on contact with objects on the surface or airborne.
Freezing fraction (n): The amount of impinging water that freezes at the point of impingement.
Freezing precipitation: Freezing rain or drizzle falling through or outside a visible cloud.
Freezing rain (FZRA): Precipitation at the ground level or aloft in the form of liquid water drops. The raindrop diameters are greater than 0.5 mm. Freezing rain exists at air temperatures B-2
APPENDIX B. NOMENCLATURE (CONTINUED)
less than 0qC (supercooled), remains in liquid form, and freezes on contact with objects on the surface or airborne.
Glaze ice: Sometimes glaze ice is clear and smooth. Glaze ice usually contains some air pockets that result in a lumpy translucent appearance. Glaze ice results from supercooled drops striking a surface but not freezing rapidly on contact. Glaze ice is denser, harder, and sometimes more transparent than rime ice. Factors, which favor glaze formation, are those that favor slow dissipation of the heat of fusion (i.e., slight supercooling and rapid accretion). With larger accretions, the ice shape typically includes “horns” protruding from unprotected leading edge surfaces. Flight crews are more likely to assess the ice shape, rather than the clarity or color of the ice, accurately from the cockpit. The terms “clear” and “glaze” have been used for essentially the same type of ice accretion. Some reserve “clear ice” for thinner accretions that lack horns and conform to the airfoil.
Gridding: The process of defining elements (finite segments, zones, spaces, volumes, etc.) that describe the surface (body) and its external flow space. The grid elements are used with a flow solver to calculate flow conditions. Typically, the gridding is denser in areas where significant changes in the flow field occur (for example, in the boundary layer, high curvature surface areas, and shocks). Since gridding affects the definition of rapid flowfield changes, it also affects the precision of the flowfield solution and resulting body surface pressures. Gridding may be held fixed for a flowfield solution. It may also be adaptive (automatically changing with a timestepping flowfield solution according to an algorithm within the CFD code). B-1 shows a gridding example.
Figure B-1. Gridding of a NACA 0012 Wing Into a Mesh of Finite Volumes for Flow Field Analysis, Drop Impingement Computation, and Ice Accretion Analysis (Reference B1).
Hard wing airplanes: Airplanes without wing leading-edge high-lift devices.
Heavy icing: A descriptor used operationally by flight crews when they report encountered icing intensity to air traffic control. The rate of ice buildup requires maximum use of the ice protection systems to minimize ice accretions on the airframe. A representative accretion rate B-3
APPENDIX B. NOMENCLATURE (CONTINUED)
for reference purposes is more than 3 inches (7.5 cm) per hour on the outer wing. A pilot encountering such conditions should consider immediate exit from the conditions.
Hybrid model: Wind tunnel model truncated aft of the leading edge and designed so the leading edge aerodynamic loading is the same as the full chord airfoil.
Ice bridging: Classic pneumatic deicing boot ice bridging occurs when a thin layer of ice is sufficiently plastic to deform to the shape of the inflated deicing boot. This occurs without the thin ice breaking or shedding during ensuing cycling of the deicing boot. As the deformed ice hardens and accretes more ice, the deicing boot becomes ineffective. Ice bridging may occur when enough supercooled water freezes during the inflated deicing boot dwell period. It will keep that shape after the deicing boot deflates and will form a deformed surface that continues to accrete ice and is unaffected by ensuing cycling of the deicing boot. A deicing boot ice bridge may also form when flying into increasingly colder ambient temperature conditions following a mixed-phase icing encounter at near-freezing temperatures. Ice bridging also refers to the ice “caps” or “bridges” between adjacent component surfaces. For example, unprotected leading edge surfaces of an elevator horn and the horizontal stabilizer.
Ice evidence probe: Device that accretes ice before ice accretes on the airframe or its components. You may use ice evidence probes as a visual icing cue.
Ice ridge: Formation of a ridge of ice typically aft of the ice protection surface. Runback ice or large drops impinging aft of the protection surface can cause ice ridges to form.
Icing encounter: An exposure to continuous or broken icing conditions until a gap or interruption longer than some preselected distance (for example, 1 nautical mile (nm)) or duration (for example, 1 minute) occurs.
Icing in cloud: Icing occurring within visible cloud. Cloud drops (diameter < 50 ȝm) will be present; freezing drizzle or freezing rain, or both, may be present.
Icing in precipitation: Icing occurring from an encounter with freezing precipitation (supercooled drops with diameters exceeding 0.05 mm, within or outside a visible cloud).
Ice accretion limit: The location farthest aft on a body at which ice accretes. You may measure this distance either as the streamwise distance from the leading edge, or as the surface distance from the stagnation point. This document defines the icing limit as the streamwise distance from the leading edge.
Impingement limit: The location farthest aft on a body where water drops impinge. This distance is usually measured as the surface length from the surface’s leading edge.
Intercycle ice: Ice that builds up on a deiced surface and exists immediately before the deice system is activated.
B-4
APPENDIX B. NOMENCLATURE (CONTINUED)
Known icing conditions: Atmospheric conditions where ice formation is observed or detected in flight.
NOTE: Because of the variability in space and time of atmospheric conditions, the existence of a report of observed icing does not guarantee the presence or intensity of icing conditions at a later time.
A report of no icing does not guarantee the absence of icing conditions at a later time.
Known or observed or detected ice accretion: Ice observed visually on the aircraft by the flight crew or identified by onboard sensors.
Lagrangian drop trajectory computation: A method for calculating the trajectory of water drops in the surrounding airflow. These trajectories are typically calculated by determining the forces exerted on individual drops. The calculation proceeds by sequentially calculating forces and resulting motion as the drop moves through the flowfield surrounding the body of interest (for example, the wing, fuselage, engine inlet, etc.). The drop trajectory calculation finishes when the drop either impacts on the body or passes it.
Langmuir distribution: A family of theoretical drop size distributions. The distributions are based on the percentages of liquid water content of each drop size (appendix I of this AC).
Light icing: A descriptor used operationally by flight crews when they report encountered icing intensity to traffic control. The rate of ice buildup requires occasional cycling of manual deicing systems to minimize ice accretions on the airframe. A representative accretion rate for reference purposes is 1/4 inch to one inch (0.6 to 2.5 cm) per hour on the outer wing. The pilot should consider exiting the condition.
Liquid water content (LWC): The mass of water in liquid cloud drops within a unit volume of cloud. It is usually given in units of grams of water per cubic meter of air (g/m 3).
Local water catch efficiency (E): The ratio of dY to ds. dY is the freestream distance between two drop trajectories that intersect a surface near a point P a distance ds apart. Letting ds approach 0, the value of E at P is the derivative dY/ds (figure B-2).
B-5