shapes may be acceptable for acquisition of flight test data necessary for handling qualities and performance evaluations and demonstrations.
(vii) Items such as fuel tank vents, cooling vents, antennas, etc., must be substantiated for maximum icing effects.
(viii) The ice protection system should be sufficiently reliable to perform its intended function in accordance with the requirements of § 29.1309. These requirements may in some instances be met by the use of sound engineering judgment during design and compliance demonstrations. In many instances, use of good design practices, failure modes and effects analysis, and similarity analyses combined with good judgment will be adequate. In some instances the need for reliability analyses may be desirable. Additional information pertaining to reliability is contained in paragraph AC 29.1309 (§ 29.1309).
(ix) The subject of lightning must be addressed. The criteria applied on rotorcraft with ice protection systems are that “the rotorcraft must be protected in such a manner to minimize lightning risk.” The general rules of § 29.1309(a), (b), and (c) are applicable to assure adequate lightning protection.
(x) Ice protection of pitot-static sources, windshields, inlets, exposed control linkages, etc., must be considered.
(xi) The impact of ice protection system failure, complete and partial, and achieving adequate warning thereof must be assessed.
(xii) The impact of delayed application of ice protection systems should be assessed. Hazardous conditions should not be apparent. Any rotorcraft characteristic changes resulting should be covered in cautionary material in the rotorcraft flight manual.
(xiii) Possible droop stop malfunction with ice accumulation and its potential hazard to the rotorcraft, its occupants, and ground personnel must be assessed.
(xiv) Possible ice shedding hazards to ground personnel or equipment in proximity to turning rotors following flight in icing conditions should be given much consideration.
(4) Flight Manual. Areas of the flight manual which may require inputs are:
(i) Operating limitations including approved types of operation and prohibiting operation in freezing rain or freezing drizzle conditions. Avoidance procedures may also be useful.
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(ii) Normal Operating Procedures. Information on the ice detection means or system and ice protection system and its capabilities.
(iii) Emergency Operating Procedures. Operating procedures containing essential information particularly with system failure.
(iv) Caution Notes. These caution notes should advise or address:
(A) Against inducing asymmetric shedding with rapid control inputs or rotor speed changes, except possibly as a last resort. Rotor speed changes appear to be more effective than control inputs in removing ice from the rotor blades of some rotorcraft.
(B) Loss in range, climb rate, and hover capability following prolonged operation in icing.
(C) The need for clean blade surfaces and use of approved cleaning solvents or ground deicing/anti-icing agents prior to starting rotors.
(D) Changes in autorotational characteristics resulting from formations.
(E) If the rotorcraft has been certificated for flight in supercooled clouds and falling and blowing snow, flight in other conditions such as freezing rain, freezing drizzle, sleet, hail, and combinations of these conditions with supercooled clouds should be avoided.
(F) The potential hazards to ground personnel, passengers deplaning, and equipment in proximity to turning rotors following flight in icing conditions.
d. Icing References.
(1) FAA Technical Report ADS-4, Engineering Summary of Airframe Icing Technical Data, December 1963.
(2) A New Characterization of Supercooled Clouds Below 10,000 Feet DOT/FAA/CT-83/22, June 1983.
(3) Advisory Circular 20-73, Aircraft Ice Protection, 21 April 71.
(4) Advisory Circular 91-51, Airplane De-ice and Anti-ice Systems, 9/15/77.
(5) FAA Report RD-77-76, Engineering Summary of Powerplant Icing Technical Data, July 1977.
(6) United States Army Aviation Engineering Flight Activity Reports:
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(i) Natural Icing Tests, UH-1H Helicopter, Final Report, June 1974, USAASTA Project No. 74-31.
(ii) Artificial Icing Tests, UH-1H Helicopter, Part 1, Final Report, January 1974, USAASTA Project No. 73-04-4.
(iii) Artificial Icing Tests, UH-1H Helicopter, Part II, Heated Glass Windshield, Final Report, USAASTA Project No. 73-04-4.
(iv) Artificial Icing Tests, Lockheed Advanced Ice Protection System Installed on a UH-1H Helicopter, Final Report, June 1975, USAAEFA Project No. 74-13.
(v) Artificial and Natural Icing Tests for Qualification of the UH-1H, Kit A Aircraft, Letter Report, USAAEFA Project No. 78-21-1.
(vi) Microphysical Properties of Artificial and Natural Clouds and Their Effects on UH-1H Helicopter Icing, Report USAAEFA Project No. 78-21-2.
(vii) Helicopter Icing Spray System (HISS) Nozzle Improvement Evaluation, Final Report, September 1981, USAAEFA Project No. 79-002-2.
(viii) Artificial and Natural Icing Tests of the YCH-4TD, Final Report, May 1981, USAAEFA Project No. 79-07.
(ix) Limited Artificial Icing Tests of the OV-ID, Letter Report, July 1981, USAAEFA Project No. 80-16, (Limited Distribution).
(x) JUH-IH Ice Phobic Coating Tests, Final Report, July 1980, USAAEFA Project No. 79-02.
(xi) Artificial and Natural Icing Tests, Production UH-60A Helicopter, Final Report, June 1980, USAAEFA Project No. 79-19.
(xii) Helicopter Icing Spray System (HISS) Evaluation and Improvements, Letter Report, June 1981, USAAEFA Project NO. 80-04.
(xiii) Artificial Icing Test of CH-47C Helicopter with Fiberglass Rotor Blades, Final Report, July 1979, USAAEFA Project No. 78-18.
(xiv) Limited Artificial and Natural Icing Tests, Production UH-60A Helicopter (Reevaluation), Final Report, August 1981, USAAEFA Project No. 80-14.
(7) Further Icing Experiments on an Unheated Nonrotating Cylinder, National Research Council, Canada Report LTR-LT-105, dated November 1979, by J.R. Stallabrass and P.F. Hearty.
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(8) Ludlam, F.H., Heat Economy of a Rimed Cylinder, Quarterly Journal, Royal Meteorological Society, Vol. 77, 1951.
(9) U.S. Army AMRDL Reports:
(i) USAAMRDL TR 73-38, Ice Protection Investigation For Advanced Rotary Wing Aircraft, J.B. Werner, August 1973, AD 7711182.
(ii) Werner, J.B., The Development of an Advanced Anti-Icing/Deicing Capability for U.S. Army Helicopters, Volume 1, Design Criteria and Technology Considerations, USAAMRDL - TR-75-34A, Eustis Directorate, U.S. Army Air Mobility R&D Laboratory, November 1975, AD A019044.
(iii) Werner, J.B., The Development of an Advanced Anti-Icing/Deicing Capability for U.S. Army Helicopters, Volume 2, Ice Protection System Application to the UH-1H Helicopter, USAAMRDL - TR-75-34B, Eustis Directorate, U.S. Army Air Mobility Research and Development Laboratory, November 1975, AD A019049.
(iv) USAAMRDL-TR-76-32, Ottawa Spray Rig Tests of an Ice Protection System Applied to the UH-1H Helicopter, November 1976, AD A0034458.
(v) USARTL-TR-78-48, Icing Tests of a UH-1H Helicopter with an Electrothermal Ice Protection System Under Simulated and Natural Icing Conditions, April 1979.
(vi) USAAMRDL-TR77-36, Final Report, Natural Icing Flights and Additional Simulated Icing Tests of a UH-1H Helicopter Incorporating an Electrothermal Ice Protection System, July 1978, AD A059704.
(10) Technical Feasibility Test of Ice Phobic Coatings for Rain Erosion in Simulated Flight Conditions, U.S. Army Test and Evaluation Command, Final Report, 4-AI-192-IPS-001, August 1980.
(11) Technical Feasibility Test of Ice Phobic Coatings in Simulated Icing Flight Conditions, U.S. Army TECOM, Final Report, 4-CO-160-000-048, September 1980.
(12) Aircraft Icing, NASA Conference Publication 2086, FAA-RD-78-109, July 1978.
(13) Helicopter Icing Review, FAA Technical Center, Final Report, FAA-CT-80-210, September 1980.
(14) National Icing Facilities Requirements Investigation, Final Report, FAA Technical Center, FAA-CT-81-35, March 1981.
(15) Aircraft Icing, AGARD Advisory Report No. 127, November 1978.
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(16) Rotorcraft Icing - Review and Prospects, AGARD Advisory Report, AR-166, September 1981.
(17) Advisory Circular 20-117 - Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Aircraft Icing, Dec. 17, 1982.
(18) Olson, W., Experimental Comparison of Icing Cloud Instruments, January 1983, NASA TM 83340.
(19) JUH-1H Redesigned pneumatic boot deicing system flight test evaluation.
Hayworth, L., Graham, M., to be published. USAAEFA Edwards AFB, California.
Project No. 834-13.
(20) An Appraisal of the Single Rotating Cylinder Method of Liquid Water Content Measurement, National Research Council Canada Report LTR-LT-92, dated November 1978, by J.R. Stallabrass.
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40 - 30 - AMBIENT TEMPERATURE - DEG F 20 10
- 10 - 2000 4000 6000 8000 10,000
PRESSURE ALTITUDE - FT FIGURE AC 29.877-1 CONTINUOUS ICING - TEMPERATURE VS ALTITUDE LIMITS Figures AC 29.877-1 through 4 represent one approach to a 10,000-foot altitude limit and Figure AC 29.877-5 represent another. See Paragraph 386b(5)(iii) for a discussion of the individual application of the two approaches.
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40 _ 30 AMBIENT TEMPERATURE - DEG F 20 • 10 10 2000 4000 6000 8000 10,000
PRESSURE ALTITUDE - FT FIGURE AC 29.877-2 INTERMITTENT ICING - TEMPERATURE VS ALTITUDE LIMITS Figures AC 29.877-1 through 4 represent one approach to a 10,000-foot altitude limit and Figure AC 29.877-5 represents another. See Paragraph 386b(5)(ii) for a discussion of the individual application of the two approaches Page D - 182
1.0 - LIQUID WATER CONTENT - GRAMS/CUBIC METER 0.8 - SEA LEVEL TO 10,000 FT PRESSURE ALTITUDE
0.6 AMBIENT TEMP °F
0.4 *70
0.2 10 20 30 40 50
MEAN EFFECTIVE DROP DIAMETER - MICRONS FIGURE AC 29.877-3 MEAN EFFECTIVE DROP DIAMETER - MICRONS Figures AC 29.877-1 through 4 represent one approach to a 10,000-foot altitude limit and Figure AC 29.877-5 represents another. See Paragraph 386b(5)(iii) for discussion of the individual application of the two approaches.
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2.0 SEA LEVEL TO 10,000 FT PRESSURE ALTITUDE LIQUID WATER CONTENT - GRAMS/CUBIC METER 1.6
AMBIENT TEMP
- 32 °F
1.2
- 14 °F
0.8
- 0 °F 10 20 30 40 50
MEAN EFFECTIVE DROP DIAMETER - MICRONS FIGURE AC 29.877-4 INTERMITTENT ICING - LIQUID WATER CONTENT VS DROP DIAMETER Figures AC 29.877-1 through 4 represent one approach to a 10,000-foot altitude limit and Figure AC 29.877-5 represents another. See Paragraph 386b(5)(ii) for a discussion of the individual application of the two approaches.
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SUPERCOOLED CLOUDS GROUND LEVEL TO 10,000 FEET
2.0 F LIQUID WATER CONTENT (gm3) 1.5 6 0 to - 15°
1.0 66 20
0.521 50 -20 to 20 - 15 TO - 20 ° C DURATION (NMI) .04 -25 °C
0.0 10 20 - 30 40 50 MEDIAN VOLUME DIAMETER (um) FIGURE AC 29.877-5 Figures AC: 29 877-1 through 4 represent one approach to a 10,000-foot altitude limit and Figure AC 29.877-5 represents another. See Paragraph 386b(5)(ii) for discussion of the individual application of the two approaches.
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CHAPTER 2. PART 29
AIRWORTHINESS STANDARDS
TRANSPORT CATEGORY ROTORCRAFT
SUBPART E - POWERPLANT
POWERPLANT - GENERAL AC 29.901. § 29.901 (Amendment 29-17) INSTALLATION.
a. Section 29.901(a):
(1) Explanation. Paragraph (a) provides a definition of areas of rotorcraft for which safety requirements are set forth under the general title, SUBPART E - POWERPLANT. This subpart includes not only major propulsive elements and power transmissive components but also powerplant controls and instruments, safety devices, including fire protection and other devices to protect personnel, and critical flight structure in event of fires.
(2) Procedures. To ensure that no certification aspect is overlooked in establishing compliance, certification engineers should make at least an informal breakdown of all components of the rotorcraft, assigning responsibility to powerplant certification engineers of all items within the above definition. While this procedure is usually straightforward, the following items of FAA/AUTHORITY powerplant responsibility are listed to minimize questions regarding authority and responsibility.
(i) Drive system components. All parts of the transmission, clutches, shafting, including the driveshafts (masts) of main and auxiliary rotors, powerplant cooling components, and powerplant instrumentation requirements under §§ 29.1305,
29.1337, 29.1543, 29.1549, 29.1551, 29.1553, 29.1555, and 29.1583.
NOTE: The division of responsibility between FAA/AUTHORITY airframe engineers and FAA/AUTHORITY powerplant engineers (in accordance with FAA/AUTHORITY practice) regarding the driveshaft is at the flange or spline interface between the driveshaft and the rotor hub. Rotor hubs, controls, blades, and associated components are the airframe engineers’ responsibility. (Industry practice may not agree with this concept.)
(ii) Engines, except for mount structure.
(iii) Auxiliary power units, except for mount structure.
(iv) Combustion heaters, except for downstream ventilation air ducting, mixing, and distribution systems and for electrical aspects of controls and safety devices.
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(v) Water/alcohol or other fluid power augmentation systems.
(vi) Engine induction systems including induction icing and snow ingestion, and exhaust systems, including exhaust shrouds and drains.
(vii) All fuel systems, including those serving engines, auxiliary power units, combustion heaters, power augmentation systems, etc., and vents and drains for those systems.
(viii) Oil systems for engines, auxiliary power units, rotor drive transmissions, and gearboxes, including grease lubricated gears and bearings of the drive system.
(ix) Cooling aspects of engines, rotordrive transmissions and gearboxes, and auxiliary power units (APU). Electrical generating equipment and hydraulic component cooling may be the responsibility of the systems and equipment engineer provided agreement is established among responsible personnel.
(x) Rotor brakes, except hydraulic, electrical, and structural aspects of nonrotating brake components.
(xi) Fire protection, including firewalls, fire extinguisher systems, fire detector systems, flammable fluid lines, fittings, and shutoff valves. The powerplant engineer has responsibility for evaluating compliance with §§ 29.861 and 29.863 as they pertain to fuel and oil systems.
(xii) Engine and transmission cowling and covering, including latches.
(xiii) Powerplant flexible controls (reference § 29.1141(c)).
(xiv) Powerplant accessories.
(xv) Pneumatic systems (engine bleed air) within the engine or APU compartments, including shut-off valves and engine isolation features of bleed systems.
(xvi) Powerplant aspects of instrument markings and powerplant aspects of flight manuals, including limitations, normal and emergency procedures, engine performance; powerplant aspects of maintenance manuals, with emphasis on the limitations section of the manual and verification of the limitations established under § 29.1521.
b. Section 29.901(b):
(1) Explanation. Paragraph (b) requires compliance with the engine manufacturers’ approved installation instructions and any applicable provisions of this subpart that the powerplant installation must be installed in a manner to ensure Page E - 2