(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
continued safe operation, that accessibility for inspection and maintenance is provided, that appropriate electrical connections (ground connections) are provided, and that allowance is provided for thermal expansion of turbine engines.
(2) Procedures.
(i) Engine Installation. Compliance with most of the detail requirements in the engine installation manual can be established by test or by design features and arrangements negotiated between the rotorcraft manufacturer and the FAA/AUTHORITY powerplant engineer. Some aspects, usually involving inlet and/or exhaust distortion limitations, vibration limitations, and aircraft/engine interface items may require direct assistance and information from the engine manufacturer to determine that compliance with the installation manual exists. Fuel control/engine/rotor system torsional matching is usually a developmental problem to be worked out before presentation of the rotorcraft to the FAA/AUTHORITY; however, final flight tests for surge or stall, torsional stability, and acceleration/deceleration schedules may require direct coordination among FAA/AUTHORITY installation engineers, engine manufacturers’ representatives, and the FAA/AUTHORITY engine certification engineers. These items are addressed specifically under § 29.939. Reciprocating, carburetor-equipped engines usually require a particular carburetor configuration to achieve adequate engine cooling. This configuration, identified as a “carburetor parts list,” must be approved for the engine under Part 33 and should be listed with the engine on the type data sheet for the rotorcraft.
(ii) Arrangement and Construction. Each item of the powerplant area of responsibility should be shown to be suitable for its intended purpose and installed to operate satisfactorily and safely between normal inspections and overhauls.
Accessories mounted on engine or transmission drive pads should be determined to be compatible with the pad limits including fit and speed range, overhang moment loads, running torque, and static torque. This latter term pertains to protection of the engine or transmission, which drives the accessory, from damage to be expected from malfunction of the accessory. This protection is usually supplied by providing a shear section in the accessory drive shaft designed to fail before exceeding the static torque limit of the engine or transmission driving component. Note that when evaluating the strength of the mechanical shear section, material allowables quoted in materials handbooks should not be used since these are minimum strength values. Shear sections should consider maximum strength values to be expected which are on the order of 130 percent of the minimum strength values. Also, it should be verified that design data for shear sections are dimensioned to limit the maximum diameter as well as the minimum diameter. Installation of starter -generators may also require verification that horsepower extraction limits are not exceeded. Special flightcrew instructions in the flight manual to monitor generator load or to disconnect electrically loaded items to protect accessory or engine-transmission pad limits should be avoided.
Environmental qualification requires consideration or protection against adverse effects of heat, sand or dust, humidity and rain, salt-laden atmosphere, and extremes of cold weather. Accessories such as generators, pumps, etc., are subjected to many of these Page E - 3
aspects during the individual qualification tests; however, satisfactory overall integrated system performance under these adverse conditions should be verified. Cold weather testing should include verification that lubricating oils and greases function properly and that engine starting procedures are safe and do not impose excessive loads on accessories, engines, or drive system components. Powerplant engineers should coordinate compliance efforts in this area with the system engineer’s investigations of compliance with §§ 29.1301 and 29.1309. Full -scale rotorcraft operations in cold weather should be required. Performance tests are required at the minimum temperature to be certified. Propulsion systems may usually be evaluated at this time.
Cold soak or overnight exposure to cold weather is appropriate followed by starting and pretakeoff procedures in accordance with the flight manual. Attention should be given to the practicality of important mandatory inspection procedures as affected by cold weather.
(iii) Accessibility. Accessibility for maintenance should be reviewed.
Typically, some maintenance activities must involve disassembly or removal of adjacent components. This should be avoided if repetitive activity can jeopardize the performance of critical or safety-related equipment. Verify that easy access exists to items such as oil system sight gauges or dip sticks, filler ports and drain valves for engines, auxiliary propulsion units, transmissions, fuel tanks and filters, etc.
(iv) Electrical (Grounding). Electrical interconnections to prevent difference of potential should be provided in the form of grounding straps or wires sized to carry the currents to be expected. Verify that the attachments for these grounding devices are not compromised by paint or zinc chromate which will tend to electrically insulate the engine or component. Note that engine mount structure should not be accepted as a grounding device since electrical current will cause corrosion at attachment points.
(v) Thermal Expansion. Axial and radial expansion of turbine engines is usually not a problem unless redundant mount arrangements are used. Special expansion provisions are usually required if engine components other than mounting points are attached to bulkheads, firewalls, other engines, or drive system components.
Engine output shaft axial or bending loads due to thermal expansion and to deflection of supports under ground or flight loads should be checked. Other components of concern are compressor inlet flanges, exhaust ducts, and rigid fluid or air lines between aircraft structure and the engine. The engine installation data will provide limit loads to be considered for parts of the engine which normally are attached to airframe components.
c. Section 29.901(c):
(1) Explanation. Paragraph (c) requires, with notable exceptions, a detailed failure modes and effects analysis (FMEA) of the various powerplant systems and components to establish that anticipated failures will not jeopardize the safe operation of the rotorcraft. Alternative methods such as top- down analysis may also be used.
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