AC 29-2C, Chg 7 2/4/2016
(ii) If required, pilots should easily manipulate the displays with one hand from their normally seated position. Pilot access of the displays and controls must meet the requirements of § 29.777 when used by the pilot-flying as primary flight information.
(2) Automatic reversion is one means to meet the requirement on § 29.1333(b) that allows required information to remain visible to the pilot flying without crewmember action. The format and arrangement of the reversionary mode is discussed below.
(i) Automatic reversion should provide the required information within one second of the detected failure of a display or the display’s inability to provide the information.
(ii) For undetectable loss of the display resulting from a backlight failure or a broken display screen, then a single button push by the pilot is acceptable.
The pilot should be able to recover the lost display of information within one second.
However, the design of the display should be such that these failures are extremely improbable.
(iii) Arrangement. Arrangement of information in a compressed or composite mode must follow the requirements of § 29.1321.
(A) Presentation of primary flight information should remain the same.
(B) Presentation of navigation information should provide for required information in as similar a location as possible as a normal display.
(C) Powerplant and required system information should be arranged in a manner that is easily accessed and readable.
(D) CAS messaging should be displayed with the ability to display all possible warnings without overflow.
(iv) Reversionary mode display format.
(A) Format of the primary flight information should not change.
(B) HSI presentation in a reversionary mode should provide the same usability and function as the non-reversionary mode. Navigation information should still be available and as close to the same format as possible.
(C) Presentation of primary powerplant information the pilot uses to set and monitor power should be prominent and graphically displayed.
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(D) Presentation of powerplant information pilots use to assess the health and ability of the powerplant to develop power can revert to numerical displays if needed. Display of these parameters numerically should include secondary cueing for the pilot in the event a parameter exceeds a cautionary or limit value. For example, the numerical digit or field should provide a visual cue regarding its status as it would in a normal display (see § 29.1322).
e. System Requirements.
(1) All parameters in EDS displays are to be designed in accordance with the relevant TSOs. TSOA does not mean that the function or hardware meets the certification requirements for the rotorcraft in which it is to be installed.
(2) A safety assessment should be provided as part of finding compliance with § 29.1309. The following sections of this AC contains guidance on safety assessments:
Section 29.1309, paragraphs c. (Failure Analysis), d. (Safety Assessment),
f. (Software), and g. (Airborne Electronic Hardware).
MG 21 (FHA)
(3) Special Considerations when determining failure condition classifications.
Consideration should be given to the type of operation that the system is intended to support. For example, failure condition classifications for IFR installations are generally higher than VFR. Information contained on a PFD is usually more critical, in most cases, than information on a MFD.
(i) VFR.
(A) In a VFR-only certificated rotorcraft misleading information will typically have a higher hazard categorization than loss of information. The design should provide mitigation to both as much as feasible, particularly for transport category rotorcraft, since night VFR can be flown in areas that do not provide pilots with good visual cues regarding the horizon or ground features.
(B) PFD. Display of any non-required information such as synthetic vision should not display misleading information. Loss of non-required information should not lead to confusion or affect the ability of the pilot to access or assess required flight information.
(C) Display of powerplant information. 14 CFR 29.1305 contains the required powerplant instrument data to be displayed. Although each item is required, care should be taken with the loss of the following, as applicable: low fuel warning, oil pressure warning for each gearbox, tachometer, and OEI power levels.
(ii) IFR. Regulations for rotorcraft certificated for IFR operations are found in Appendix B to part 29.
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AC 29-2C, Chg 7 2/4/2016
(iii) Field-Loadable Software (FLS) as part of the TC, STC, ASC, and ASTC installation. FLS is software that can be loaded without removal of the equipment from the rotorcraft installation. FLS can refer to either executable code or data. FLS might also include software loaded into a line replaceable unit (LRU) or hardware element at a repair station or shop. When obtaining certification approval for utilization of the FLS capability, refer to the guidance in FAA Order 8110.49.
(iv) Navigation Database Qualification. For area navigation equipment, the navigation database is an essential component of the ability of the equipment to perform its intended function. RTCA Document DO -200A, Standards for Processing Aeronautical Data, contains guidelines pertaining to the navigation database. .
Consider obtaining a Type 2 Letter of Authorization for databases used for Localizer Performance with Vertical Guidance in addition to the required documentation. See AC 20-153A for additional information. See AC 20-153A for additional information.
(4) Environmental qualification. EDS displays should meet the appropriate RTCA Document DO-160G environmental qualifications for rotorcraft. Rotorcraft environments can be more hostile than fixed-wing environments. Give special attention to the temperature and vibration qualifications. See section 29.1309 of this AC for more guidance.
(i) Cooling.
(A) Perform cooling evaluations for the installed components.
(B) Temperature Survey to Determine Proper Cooling of EDS Components.
(1) Equipment Requiring Cooling Test. As with any avionics equipment, good engineering judgment may deem that all components of the EDS should have an in-flight temperature survey performed to ascertain that the thermal environmental tolerance of the system components is not exceeded. Usually, the following general guidelines may be used to aid in determining when an in-flight temperature survey is warranted.
(i) Equipment specified by the manufacturer to require forced air cooling (by an airframe-mounted system) usually requires a temperature survey.
(ii) Equipment that is not specified as requiring forced air-cooling may usually have its critical thermal environment substantiated by laboratory testing.
(2) Temperature Survey Testing. The temperature tests for the EDS units should consist of a short-term test of approximately 30 minutes, which accounts for a rotorcraft that has heat-soaked on the ramp. A factor of 25° F should be added to the maximum corrected temperature to account for “greenhouse effect.” A long-term Page MG 19 -32
test should be accomplished at various altitudes and limiting (low and high) airspeeds.
All avionic equipment should be turned on during the long-term tests, and the cockpit panel lights should be operated at full intensity. The environmental control unit or air-conditioning system should not be operated during the short-term and long-term tests; however, any windows or vents, which are part of the basic TC of the rotorcraft, may be utilized to ventilate the pilot’s stations during the long-term test. Both of these tests should be corrected to the maximum temperature for which the rotorcraft is certificated (maximum outside air temperature) and a standard lapse rate for altitude
(i.e., 3.6° F/1,000 feet), as specified in this guidance (refer to section 27.1309 of this AC). This lapse rate should be applied regardless of the hot day sea level temperature the applicant chooses to certificate for operation. If an airframe cooling s ystem is necessary to keep the display units within acceptable temperature limits, then the pilot(s) must be made aware of a failure or malfunction of this required cooling system.
Some type of cockpit visual annunciation with the capability to perform a preflight test is usually utilized to fulfill this requirement.
(ii) HIRF. Perform HIRF testing in accordance with § 29.1317 and the guidance in section 29.1317 of this AC.
(5) Night vision imaging system (NVIS) lighting. If the EDS is designed with night vision goggle (NVG) compatibility for installation in a NVIS lighting modified cockpit, refer to MG-16 of this AC and RTCA Document DO-275 for lighting performance guidance. Modifications to EDS displays should preserve color uniformity across the cockpit. Most EDSs incorporate color, as a result, in order to preserve the EDS colors close to the rotorcrafts designed colors, the NVIS lighting system should be modified to be compatible with Class B NVGs. Lighting compatible with Class A NVGs may not provide the correct color hues (e.g., red colors tend to look orange or amber, yellow colors tend to have a green tint in daylight, etc.).
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This is new AC 29-2C guidance material.
CHAPTER 3
AIRWORTHINESS STANDARDS
TRANSPORT CATEGORY ROTORCRAFT
MISCELLANEOUS GUIDANCE (MG) AC 29 MG 20. HUMAN FACTORS (HF)
a. Background. The purpose of this miscellaneous guidance section is to provide applicants with general guidelines on how to approach compliance with 14 CFR part 29 sections that have provision relating to human factors (HF) or human performance. The intent of this guidance is to assist in understanding the HF implications of the more frequently referenced regulations. This guidance also provides examples of how to address HF implications when demonstrating compliance with these regulations. This information should help determine whether HF-related requirements have been adequately addressed.
(1) Developments in technology and the affordability of advanced avionics provide for the installation of sophisticated systems into rotorcraft. As a result, the level and characteristics of pilots’ interactions with cockpit and avionics systems is changing, particularly for rotorcraft that are not capable of operating under instrument flight rules (IFR). Additionally, integrating new technologies, such as a satellite-based augmentation system (SBAS) or wide area augmentation system (WAAS) increases the rotorcraft’s avionics system capabilities to perform functions and operations it was not previously capable of performing. These new capabilities create HF issues related to pilot workload that should be evaluated along with the systems integration. Poor system integration often results in applicants relying on the pilot to work around a design issue. This approach, coupled with complex pilot interfaces, can lead to pilot error and may inhibit the pilot’s ability to recover from errors without undue concentration or fatigue. Some HF implications are straightforward and easily complied with, while others may be more complex. A partial list of rules that have HF implications, particularly those that relate to pilot workload, is included in paragraph
b.(2) below. The HF guidance contained in this MG is consistent with the goals identified in the FAA Industry Guide to Product Certification (Jan 99) and the FAA Industry Guide to Avionics Approvals (Apr 01).
(2) The requirements of part 29 Subparts A through G applies to both VFR and IFR rotorcraft approvals. Rotorcraft approved for IFR operations must also meet the additional requirements of Appendix B to part 29. (Airworthiness Criteria for Helicopter Instrument Flight). Additionally, Appendix D to part 25 contains information regarding criteria for minimum crew determination for airplanes operating under IFR conditions, which may be beneficial for determinations in rotorcraft.
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AC 29-2C, Chg 7 2/4/2016
(3) As a normal part of the certification project, the applicant and the FAA/AUTHORITY usually establish an early and formal written certification plan on the certification basis, the methods of compliance, and the schedules for completing the certification project. Both parties should ensure coverage of the HF aspects of the rules in the plan. If the applicant chooses, it can submit a separate human factors certification plan. These early discussions can reduce the applicant’s time and cost to obtain certification.
(4) The flight test team usually performs the HF evaluations. However, HF engineers and test pilots should be involved early in the design, during cockpit integration tests, and early in the human-machine interface evaluations. Identify and develop pilot-system interfaces and interactions in the basic design to reduce the risk of having an interface issue identified after the system design is “frozen” and mature.
b. Related Regulations and Documents.
(1) (1) HF related regulations. Not all of the regulations listed require specific HF means of compliance. Some are self-explanatory and straightforward, while compliance with others is determined during flight test as part of their normal course of testing and evaluation. However, each regulation should be noted in the certification plan.
(2) Many of the regulations with HF implication are also within the purview of other engineering disciplines; therefore, demonstration of compliance with 14 CFR part 29 may include more than one engineering discipline. For regulations with HF implications, consider identifying which discipline or individual will be responsible for demonstrating compliance with these regulations. The following contains a partial list of part 29 regulations related to human factors and performance.
14 CFR Section Title
29.2 Special retroactive requirements.
29.33(b)(3), (c)(2), (e) Main rotor speed and pitch limits.
29.45(a), (f) General.
29.51(a) Takeoff
29.75(a), (b) Landing
29.141(b) General.
29.143(a), (d), (e) Controllability and maneuverability.
29.151(a), (b) Flight controls.
29.161(b) Trim control.
29.171 Stability: general.
29.177 Static directional stability.
29.239 Spray characteristics.
29.251 Vibration.
29.561(a), (b) General.
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14 CFR Section Title
29.611 Inspection provisions.
29.672(a), (b), (c)(1)(2)(3) Stability augmentation, automatic, and power-operated systems.
29.679(a), (b) Control system locks.
29.685(d)(10) Control system details.
29.771 (a), (b), (c) Pilot compartment.
29.773(a), (b) Pilot compartment view.
29.777 (a), (b) Cockpit controls.
29.779 (a), (b) Motion and effect of cockpit controls.
29.783(b) Doors.
29.785 Seats, berths, litters, safety belts, and harnesses.
29.801(a), (b), (d) Ditching.
29.805 (b) Flight crew emergency exits.
29.807(a), (b), (d) Emergency exits.
29.859(e)(3) Combustion heater fire protection.
29.863(c) Flammable fluid fire protection.
29.865(b)(1)(2), (c)(3)(5) External loads.
29.901(b)(2)(5) Installation.
29.921 Rotor brake.
29.955(c) Fuel flow.
29.999(b)(2)(3)(i) Fuel system drains
29.1141(a)(b)(d)(f)(2) Powerplant controls: general.
29.1143(b), (c), (e) Engine controls.
29.1145 (a) (b), (c) Ignition switches.
29.1147 Mixture controls.
29.1151 Rotor brake controls.
29.1189(e), (f) Shutoff means.
29.1301(a), (b) Function and installation.
29.1303 Flight and navigation instruments.
29.1305 Powerplant instruments.
29.1309(a), (b), (c)(4) Equipment, systems, and installations.
29.1321 Arrangement and visibility.
29.1322 Warning, caution, and advisory lights.
29.1329 Automatic pilot system.
29.1333(b) Instrument systems.
29.1335 Flight director systems.
29.1337(b), (e)(2) Powerplant instruments.
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AC 29-2C, Chg 7 2/4/2016 14 CFR Section Title
29.1351(b)(5), (6) General.
29.1357(d) Circuit protective devices.
29.1381(a), (b) Instrument lights.
29.1383(b), (c) Landing lights.
29.1401(a)(1) Anticollision light system.
29.1411(a), (b) (1) General.
29.1415(b), (d) Ditching equipment.
29.1501(b) General.
29.1523 Minimum flight crew.
29.1525 Kinds of operations.
29.1541(b)(1) General.
29.1543(b) Instrument markings: general.
29.1545 Airspeed indicator.
29.1549 Powerplant instruments
29.1555 Control markings.
29.1559 Limitations placard.
29.1561 Safety equipment.
29.1583 Operating limitations.
Appendix B to Part 29, IV Static longitudinal stability.
Appendix B to Part 29, VI Dynamic stability.
Appendix B to Part 29, VII Stability augmentation system (SAS).
Appendix B to Part 29, VIII Equipment, systems, and installation.
(3) Advisory Circulars (AC) and Related Documents (refer to the current version).
Note: ACs, Orders, and policy statement memoranda are available on the FAA website: www.faa.gov.
(i) ACs AC Title 20-175 Controls for Flight Deck Systems 21-40 Guide for Obtaining a Supplemental Type Certificate 27-1 Certification of Normal Category Rotorcraft (Sections related to Appendix B and the requirements within Appendix B identified in the certification plan with HF/HP issues) 29-2 Certification of Transport Category Rotorcraft (Sections related to Appendix B and the requirements within Appendix B identified in the certification plan with HF/HP issues) Page MG 20 -4
(ii) Related Documents Document Title SAE- ARP 4155 Human Interface Design Methodology for Integrated Display Symbology SAE-ARP 4033 Pilot-System Integration SAE-ARP 4102 Flight Deck Panels, Controls, and Displays SAE-ARP 4102-7 Electronic Displays SAE-ARP 4927 Integration Procedures for the Introduction of New Systems to the Cockpit SAE-ARD 50019 Human Engineering Issues for Enhanced Vision Systems DOT/FAA/RD-93/5 Human Factors for Flight Deck Certification Personnel DOT/FAA/ AM-13/21 Multi-Function Displays: A Guide for Human Factors Evaluation
c. Scope.
(1) The objective of this MG is to provide guidance regarding the regulatory HF components that should be considered during a certification project for rotorcraft. While applicants are the main target audience, this guidance can be used by all FAA project team members including:
(i) Aircraft Evaluation Group (AEG) inspectors,
(ii) avionics engineers,
(iii) project managers,
(iv) flight test pilots and engineers,
(v) HF specialists and engineers,
(vi) propulsion engineers, and
(vii) systems engineers.
(2) This MG is general and high level, covering the HF aspects of certificating a rotorcraft or system installation on a new or previously-certificated transport category rotorcraft. It is intended to guide applicants and certification engineers on what they should consider regarding HF during project planning and execution..
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AC 29-2C, Chg 7 2/4/2016
d. System Description.
(1) General. Develop a system description with enough detail to provide for a common understanding of the design, function, and operation of the system.
Thoroughly detail any new or novel features, interfaces, controls, or other pilot-system interfaces that pilots will use.
(2) Intended Function (§ 29.1301).
(i) Describe the intended functions of the major pilot-system interfaces. In order to assess the potential hazards posed by the installation of a system, there must be a clear understanding of the function provided by the system and the declared intended function. Accomplish this by providing a detailed description of how the system supports the specified function(s). For example, describing a function or component, such as a display, as “for pilot situation awareness only” or, “for situational awareness only” is not adequate regardless of whether the function or component is required by the regulations. A better example for a non-required function might be “to increase terrain awareness.” Identify the following items, as appropriate, focusing on new or unique features that affect the crew interface or the allocation of tasks between the pilot(s) and the rotorcraft systems:
(A) The intended function of the system from the pilot’s perspective (coupling between the pilot and the system)..
(B) The role of the pilot relative to the system.
(C) The degree of integration or independence with other flight deck equipment.
(D) The novelty of the system or features of the system.
(E) The criticality of the system and alerting mechanism.
(F) Methods to reduce the occurrence and consequences of crew error when interacting with the system.
(G) The system features accessible to the pilot other than those normally considered needed for flight. For example, whether field loadable software, maintenance, and configuration functions are accessible by the pilot in flight and on the ground, or whether they are accessible only by maintenance personnel.
(ii) Use the following information to evaluate whether the intended functions and associated tasks are sufficiently detailed and specific:
(A) Whether each feature includes a statement of the intended function and a description of the task associated with this feature.
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(B) Whether there are assessments, decisions, or actions required by the pilot for these intended functions.
(C) Whether other information is to be used in conjunction with these intended functions (for example, other cockpit systems), in combination with the system.
(D) Whether the operational environment in which these intended functions are to be used is adequately described (e.g., VFR, IFR, phase of flight).
(3) Cockpit layout (§§ 29.771, 29.773, 29.777, 29.1303, 29.1305, 29.1321,
29.1329, and Appendix B to part 29).
(i) Drawings of the cockpit layout showing positions of system components, even if preliminary, are beneficial for providing an understanding of the intended overall cockpit arrangement (controls, displays, sample display screens, seating, stowage, and so forth). Including measurements and dimensions of displays, their locations and locations of controls relative to the pilot’s central line of vision or the design eye position is also beneficial to both the applicant’s and certification authority teams. As the system design changes, keep the certification team updated so they are current on proposed changes. Give special attention to the following, especially if they are novel or unique:
(A) Arrangements of the controls, displays or other cockpit or flight deck features or equipment.
(B) Controls, such as cursor control devices, touchscreen displays, or new applications of existing control technology.
(C) Content, format, and function of the pilot interface on the display as generated by the systems software.
(D) Display hardware technology.
(E) Screen usage, alerting mechanisms, and mode annunciation.
(ii) Sketches of the crew interfaces for the specific systems or the items listed above can be helpful in providing an early understanding of the features that may face certification issues.
(4) Underlying principles for automation logic (§ 29.1309, § 29.1329, and Appendix B to part 29). Define the system’s automated functions design early in the process. The automation features should follow a design philosophy that supports the intended functions regarding the system behavior; modes of operation; and pilot interface with controls, displays, and alerts. For designs that involve significant automation, the way automation operates and communicates that operation to the pilot Page MG 20 - 7
- AC 29-2C, Chg 7 2/4/2016 can have significant effects on the crew interface. The system description should include, but not be limited to:
(i) Pilot actions to engage or disengage, or activate or deactivate modes and features.
(ii) Principles underlying mode transition.
(iii) Mode annunciation scheme.
(iv) Automation engagement or disengagement principles.
(v) Level of automation.
(vi) Logic diagrams and complexity of the logic, if available.
(vii) Failure modes, how they appear to pilots, and how pilots’ interaction with the system and rotorcraft changes.
(5) Operational considerations (§ 29.1523, Minimum flight crew; § 29.1525, Kinds of operations). Consider consulting the AEG inspector that is responsible for the make and model of rotorcraft on the system installation.
(i) Pilot characteristics (§ 29.1523). The FAA has not accepted certain designs, in past projects, that specifically relied on crew resource management or certain pilot characteristics to mitigate a system design flaw. Consider assessing the level of certification, skill, and knowledge a “nominal pilot” possesses in order to evaluate the pilot workload when interacting with the system and rotorcraft.
(ii) Identify the operations the system is designed to support. Although sometimes considered less complex than installations for operation under IFR, the HF evaluation of installations for operation under VFR should include the same rigor, as both present HF challenges to the pilot. For example, complex systems or systems that require the pilot to spend considerable time interfacing with a system’s functions and interactions with other rotorcraft systems will require the pilot to allocate attention from flying the rotorcraft. The results are increased workload with varying changes in the pilot’s ability to attend to flying the rotorcraft. The following are some considerati ons:
(A) For rotorcraft operating only under VFR, describe the operations the system is meant to support, taking into account day and night operations. For example, for installation of an electronic display systems (EDS) display suite that integrates with external GPS navigators, consider:
(1) The effect of the pilot-system interface on the pilot’s attention allocation and workload.
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