40.
30 AMBIENT TEMPERATURE - DEG F 20 • 10 10 2000 4000 6000 8000 10,000
PRESSURE ALTITUDE - FT FIGURE AC 29.1419-2 INTERMITTENT ICING - TEMPERATURE VS ALTITUDE LIMITS Figures AC 29.1419-1 through 4 represent the approach to a 10,000-foot altitude limit.
See Paragraph b(5)(iii) for a discussion on this approach.
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1.0 - LIQUID WATER CONTENT - GRAMS/CUBIC METER 0.8 - SEA LEVEL TO 10,000 FT PRESSURE ALTITUDE
0.6 AMBIENT TEMP °F 15
0.4 *70
0.2 10 20 30 40 50
MEAN EFFECTIVE DROP DIAMETER - MICRONS FIGURE AC 29.1419-3 CONTINUOUS ICING - LIQUID WATER CONTENT VS. DROP DIAMETER Figures AC 29.1419-1 through 4 represent one approach to a 10,000-foot altitude limit.
See Paragraph b(5) (ili) for a discussion on this approach.
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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
0.4 10 20 30 40 50
MEAN EFFECTIVE DROP DIAMETER - MICRONS FIGURE AC 29. 1419-4 INTERMITTENT ICING - LIQUID WATER
CONTENT VS DROP DIAMETER Figures AC 29.1419-1 through 4 represent one approach to a 10,000-foot altitude limit.
See Paragraph b(5) (ili) for a discussion of this approach.
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SUBPART F - EQUIPMENT
MISCELLANEOUS EQUIPMENT AC 29.1431. § 29.1431 ELECTRONIC EQUIPMENT.
a. Background. Th is section contains some specific requirements for electronic equipment in the rotorcraft. The principal requirements of this section are that radio and navigation equipment must be free from hazards, both in themselves and in their effect on any other items installed in the rotorcraft, and that operation of the radio and navigation equipment does not interfere with operation of any other required avionics.
The increased use of complex equipment that integrates communication and navigation functions increases the likelihood of common mode failures resulting in simultaneous loss of communication and navigation functions. Total non- restorable loss of communication and navigation information is considered to be a catastrophic failure condition for IFR operations.
b. Procedures. In showing compliance with this section, tests and analysis should be performed as necessary to determine that:
(1) All radio and navigation equipment is installed and operated in such a manner that it does not result in hazards to the rotorcraft. It also should not have an effect on any other components of the rotorcraft to the extent that it creates a hazardous condition. Consideration should be given to the effects of critical environmental conditions. The environment can easily be the cause of common mode failures.
Temperature extremes in the rotorcraft may exceed the temperature to which the system was qualified. Additional considerations include:
(i) An analysis, per SAE ARP 4761, to assure there is no single condition or fault which can cause multiple channels, systems, circuits, etc. to fail simultaneously.
An example of this could be a common power supply for both communication and navigation functions.
(ii) Addressing each potential common cause fault case and identifying the corresponding mitigation or assurance for precluding that fault. Examples of this are shown in MG-13.
(iii) Mitigating features which include “shake and bake” testing on each LRU, dissimilar design, and architecture considerations such as simplex back-up systems.
(2) All radio and navigation systems and equipment should be installed and operated in a manner that will not have a detrimental effect on the proper functioning of any electronic equipment or system required by the FAR. It should be noted that §§ 29.1301 (reference paragraph AC 29.1301) and 29.1309(b) through (d) (reference paragraph AC 29.1309) apply to all installed equipment and systems and § 29.1309(a) Page F – 106
applies to all systems and equipment required by Parts 21 through 49. As an example of showing compliance with this section, consider a high frequency radio (HF) system installation. The first thing to determine is that the installation and operation of the HF system cannot create a hazard. Consideration may be necessary in hazardous situations such as precipitation on the antenna. Next, it should be determined that the operation of the HF does not cause interference to a system whose functioning is required by the FAR. An example of unacceptable interference would be if operating the HF transmitter caused one of the navigation radios to malfunction.
(3) Finally, it should be determined that other systems do not interfere with the HF system. Additional guidance on the testing of avionics equipment and installation is contained in paragraph AC 29 MG 1.
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AC 29-2C, Chg 3 9/30/2008 AC 29.1433. § 29.1433 VACUUM SYSTEMS.
a. Explanation. Vacuum systems have been utilized on some rotorcraft to provide an energy source for the flight instruments. This specific rule addresses the potential hazards which are peculiar to vacuum system installations. The possible fire hazards presented by these systems are of particular concern.
b. Procedure. The following items should be specifically addressed when evaluating a vacuum system installation:
(1) Pressure and Temperature Protection. The high- pressure outlet of the vacuum pump should have a means to automatically relieve the pressure if it becomes excessively high or the air temperature becomes excessively hot.
(2) Fire Hazard Protection. The components of the vacuum system that are mounted in a designated fire zone should be fire resistant. This includes engine or transmission driven pumps if they are in a fire zone. The discharge side of the pump may emit flammable fluids. This discharge side of the pump, along with its associated lines and fittings, should meet the criteria in paragraph AC 29.1183.
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AC 29.1435. § 29.1435 HYDRAULIC SYSTEM S.
a. Reference Regulations. The following sections of Part 29 are either incorporated in the provisions of § 29.1435 or are otherwise applicable to hydraulic system design:
(1) Section 29.695. Paragraph AC 29.695 covers power boost and power operated control systems.
(2) Section 29.861. Paragraph AC 29.861 covers fire protection of structure, controls, and other parts.
(3) Section 29.863. Paragraph AC 29.863 covers flammable fluid fire protection.
(4) Section 29.1183. Paragraph AC 29.1183 covers lines, fittings, and components.
(5) Section 29.1185. Paragraph AC 29.1185 covers flammable fluids.
(6) Section 29.1189. Paragraph AC 29.1189 covers shutoff means.
(7) Section 29.1309. Paragraph AC 29.1309 covers the requirements for functioning and reliability, and prevention of hazards if malfunctions or failures occur.
(8) Section 29.1322. Paragraph AC 29.1322 covers warning, caution, and advisory lights.
b. System Design. It is assumed that the hydraulic system is to be utilized to operate the primary control system of the rotorcraft and the rotorcraft cannot be safely operated without the hydraulic system.
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(1) Section 29.1309, paragraphs (a) and (b), provides for functioning reliably under any foreseeable operating condition and prevention of hazards after any malfunction or failure.
(2) The substantiating data should include a failure analysis that considers every possible system component failure, such as (but not limited to) ruptured lines, pump failure, regulator failure, ruptured seals, clogged filters, broken pilot valve connections, etc.
(3) The requirements of § 29.1309(a) and (b) are met by dual independent hydraulic systems from the reservoir, hydraulic pump, regulator, connecting tubing, and hoses through the actuators. There must be no commonality in the fluid- containing components. A break in one system should not result in fluid loss in the remaining system.
(4) The pumps should be separated as far as practicable; i.e., on opposite sides of the rotor drive transmission, on separate engines, or one pump on an engine and the other on the rotor drive transmission. The tubing and hoses should also be routed with as much physical separation as practicable. The purpose of this separation is to prevent total loss of the hydraulic systems in the event of a malfunction such as fire, or rotor burst wherein one projectile could disable both systems.
(5) Dual actuators must be designed to assure that any single failure, such as a cracked housing, broken interconnecting input, or output link, does not result in loss of total hydraulic system function.
(6) If the assumption under (b) above does not apply and the pilot can control the rotorcraft without undue fatigue after loss of the hydraulic system, then a single hydraulic system is acceptable.
(7) The pressure-indicating system required by § 29.1435, paragraph (a)(3), can be satisfied with a dial, vertical scale, or digital indicator. The indicator should enable the crew to detect pressure trends. Paragraph AC 29.1322 concerns § 29.1322 regarding proper colors for annunciators if they are used to supplement the indicating system.
(8) An analysis or a combination of analysis and tests must be included in the substantiating data file to show compliance with paragraphs (a)(1), (a)(2), and (a)(4) of § 29.1435.
(9) Extra caution should be exercised to assure that control input forces at the mechanical connection to the actuator pilot valves do not exceed their intended value.
Consideration should be given to the most adverse tolerance buildup in parts fabrication and control system rigging.
Page F – 116
(10) The substantiating data should show that the hydraulic components will perform their intended function reliably under the most adverse continuous and short-time environmental conditions to which they are exposed. These variables include but are not limited to temperature, humidity, vibration, altitude, and shock.
Paragraph AC 29.1309.b.(9)(ii)(A) is a method of temperature correction to cover the entire operating temperature envelope being certified.
(11) The system component strength must be sufficient for its material fatigue life to exceed the number of cycles imposed by pump ripple pressure.
c. Installation Precautions and Fire Protection.
(1) All components and tubing routed through fire zones may be designed to comply with the fire protection requirements of §§ 29.1183, 29.1185, and 29.1189. As an alternative, a fireproof shield may be used around the component to be protected.
The component should be sufficiently protected to assure fluid leakage will not occur and fuel the fire.
(2) All hydraulic lines should be sufficiently isolated from the engine bleed air lines, environmental control unit, oil cooler, or other heat source to assure expected line life.
(3) If flammable hydraulic fluid is used, the hydraulic components should be isolated from ignition sources to assure that failure of any of the hydraulic components will not result in a fire or explosion. In t he case of electrical ignition sources in the proximity of hydraulic components, the electrical equipment should be hermetically sealed or otherwise substantiated as not being an ignition source. (Reference paragraph AC 29.1309.b.(9)(i)(D).)
(4) The installation detail should be thoroughly reviewed for adequacy of line clamping and clearance from sharp edges. As much physical separation as possible should be provided between hydraulic lines and electrical cables.
(5) While the control system is being moved from stop to stop, observation should be made to determine that hose flexing and tube bending is minimized.
d. Testing.
(1) Individual components should be substantiated by either vendor’s or primary manufacturer’s laboratory test reports. These tests should establish performance ratings such as pressures, flow rates, environmental capability, etc., to be approved.
(2) After the total system is installed, ground tests should be conducted to assure the system performs as intended and that each component is functioning within its design rating.
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AC 29-2C, Chg 4 5/1/2014
(3) If the total system design permits each combined independent power source and actuator to be disabled by shutoff valves, engine shutdown, etc., each combination should be disabled and the remaining combination verified to perform the necessary control functions. The test should be accomplished again with the functioning combination disabled and the disabled combination functioning. These tests should be accomplished first by ground tests, then repeated in flight.
(4) Temperature and pressure instrumentation should be provided at the critical points in the system to meet the provisions of d(2) above. Temperature results should be corrected for hot day conditions. (Paragraph AC 29.1309.b.(9)(ii)(A) gives a recommended procedure.)
(5) All controls should be cycled throughout their complete range of travel while accomplishing d(2) above.
(6) Satisfactory hydraulic system performance should be verified while the pump drive sources (rotor, engine, etc.) are individually varied throughout their approved operating range.
(7) Flight tests should be conducted throughout all altitudes, maneuvers, and control ranges while the system is instrumented as in d(2) and (4) above to determine that component ratings are not exceeded.
AC 29.1439. § 29.1439 PROTECTI VE BREATHING EQUIPMENT.
a. Explanation. This paragraph prescr ibes minimum requirements for eye and respiratory protection from toxic atmospheres during in-flight emergencies if one or more cargo or baggage compartments are to be accessible in flight. The equipment provided shall assure the crew protection against an oxygen deficient, toxic or highly irritating environment such as smoke.
b. Procedures.
(1) The equipment should provide a good fit for the range of intended users.
(2) A donning procedure should be provided by the manufacturer, evaluated, and the final procedure included in the Rotorcraft Flight Manual.
(3) The equipment should accommodate crewmembers who wear corrective glasses. Nominal position of eyeglasses should not be compromised. The equipment should not cause distortion or undue discomfort.
(4) The equipment donned under the stress of emergency should orient to the face and head, and interface to mating equipment, if required, in an obvious and Page F – 118
uncomplicated manner. Respiratory and eye protection should be provided in a manner that does not compromise the crew’s ability to perform required tasks.
(5) Any system that interfaces with existing components, should demonstrate satisfactory performance when operated with these components.
(6) For systems that require positive pressure to furnish satisfactory protection, a positive pressure vs. gas consumption curve should be supplied with the system along with instructions on the proper matching of the system or components to assure the minimum duration requirements of the standard are met.
(7) TSO-C99 and C116 are for Protective Breathing Equipment. If equipment is considered that is not qualified to one of these TSO’s, it is recommended that their provisions be reviewed and used as a basis for a qualification program for the equipment being considered. TSO -C99 provides minimum performance requirements for emergency equipment which provides flight deck and cabin crewmembers with eye and respiratory protection from toxic atmospheres during in-flight emergencies.
TSO-C116 results in protective breathing equipment that provides any crewmember with the ability to locate and combat a fire within the aircraft cabin or any other accessible compartment.
(8) Additional information regarding oxygen supply systems can be found in paragraph AC 29 MG 6.
AC 29.1457. § 29.1457 (Amendment 29-6) COCKPIT VOIC E RECORDER.
a. Explanation. The function of the cockpit voice recorder (CVR) is to provide a rec ord of the crew communications preceding an accidental crash of the rotorcraft.
Over the last several years, the National Transportation Safety Board (NTSB) has determined that CVR’s are invaluable in determining probable cause of an accident.
Because of this fact and acts of Congress, the use of CVR’s is required on many rotorcraft involved in passenger-carrying operations.
b. Procedures. The following a reas are of particular consideration in the approval of a CVR installation.
(1) Equipment Qualifications. The CVR must be approved. The most common way of obtaining an approval is to qualify the CVR (and associated control panel, if appropriate) to TSO C84.
(2) Cockpit Area Microphone (CAM). The third channel of recorded information is specified to be from a cockpit area microphone or from voice activated lip microphones at the first and second pilot stations. It should be noted that a continuously recording or “hot” microphone at both the first and second pilot stations would satisfy this CAM requirement. Due to the ambient noise level in rotorcraft, the use of “hot” microphone results in objectionable constant “hissing” in the pilot’s Page F – 119
headsets. Therefore, it is recommended that “hot” microphones not be used on rotorcraft.
(3) CVR Mechanical Installation. The CVR or the portion thereof which contains the recording should be physically located to enhance the probability of the recording surviving a crash. Normally, such a location would be in the lower portion of the rotorcraft as far aft as possible.
(4) Intelligibility of Recordings. Tests should be accomplished to determine that the recording is intelligible enough to make a positive identification of the speaker and the words or phrases spoken. This is usually accomplished by a flight test that provides an operation to produce the maximum cockpit background noise. The operation should provide for the normal speech of all crewmembers to be recorded on the pertinent channels. Then, during playback, preferably using a different listener, the listener should be able to identify the different crewmembers, the words and phrases spoken by the crew, and the radio communications made by and to the crew. The use of special filters and multiple playbacks to improve intelligibility is acceptable.
(5) Electrical Power Supply. The rule requires that the CVR should be supplied with power from a reliable source that does not jeopardize essential or emergency loads. For Category A rotorcraft, the CVR is not an essential load as specified in § 29.1309(e). However, since the functioning of the CVR is required by operating rules for some operations, it should be given priority over other nonessential loads.
(6) Self-Test Function. The CVR should be provided with a means in the cockpit that will allow a test to ensure the CVR is functioning properly. This may be accomplished by a manual playback feature.
(7) Bulk erasure. If this function is provided, the installation should be as follows:
(i) Any probable malfunction will not cause erasure of the recording medium.
(ii) The crash impact forces will not cause activation of the bulk erasure function.
(iii) Inadvertent actuation of the bulk erasure function is minimized.
Usually, this is accomplished by requiring two separate actions to operate the bulk erasure.
AC 29.1459. § 29.1459 (Amendment 29-25) FLIGHT RECORDERS .
a. Explanation. The function of the flight recorder, sometimes referred to as a flight data recorder, is to provide a record of various aircraft and air data parameters during the operation of the rotorcraft. This data is utilized by accident investigators to Page F – 120