(J) Any other aircraft or personal equipment required for the operation (e.g., curtains, NVG stowage, extra batteries for NVGs).
(ii) The mounting position of all instruments, switches, position labels, and controls should be visible to the pilot during unaided and aided flight and in all cockpit lighting conditions (day and night).
Instruments required for NVG operations should be located in or as close as possible to the pilot’s primary scan. For example, a radar altimeter, which is required for NVG operations, should be located as close as possible to the primary instrument cluster. Locating the radar altimeter on the opposite side of the instrument panel increases the pilots’ scan and workload. The instruments, switches, and placards should be free from reflections. Warning, caution, and advisory annunciation devices should be conspicuous, NVG compatible, and clearly visible to the pilot (day and night). Gauge and instrument markings should be clearly seen and the colors of the markings maintained. Limited NVG visual degradation of one element on the USAF Tri-Bar chart (12%) is allowed for master caution, master warning, and warning messages or annunciators since these lights need to attract the pilot’s attention.
Other than master caution and warning lights and warning annunciators, no other light or reflection in the cockpit may degrade NVG visual acuity from the acuity measured viewing the target through the windscreen. Find a copy of the USAF Tri-Bar chart in the checklists at:
http://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/nvis/.
(iii) Interior Lighting. Internal lighting systems should not adversely affect the performance of the NVG.
NVIS-modified instrument lights, illuminated instrument markings and applicable signs must comply with § 29.1381. Compliance should be demonstrated during both aided and unaided operations. . In past applications, the use of NVIS White provided good color discrimination on instrument markings. If a piece of equipment, instrument, switch, indicator, or panel was illuminated prior to the NVIS lighting installation, it should be illuminated by the NVIS lighting modification. Shades of red, amber, or green in the cockpit that are difficult to distinguish as red, amber, or green in all lighting conditions are not acceptable since pilots must be able to readily distinguish all aircraft cautions, warnings, advisories, and instrument markings without confusion. Similarly, NVG filtering should not result in different colored illuminations becoming difficult to distinguish from each other. For example, when using amber for cautions, the NVIS filtering should not result in amber caution lights and green advisory lights appearing similar in color.
Because technology is available that allows “NVG-friendly” reds to appear red without interfering with Class B NVGs, the use of NVIS-Red (which appears orange or amber to the eye) is not acceptable when warning indicators in the cockpit are red. Additionally, NVIS -Red with orange hue is not acceptable in cockpits with amber caution lights or indicators since they are similar in color. Interior cabin, passenger, or emergency lighting should not interfere with NVG operations. Relying on a curtain between the passenger compartment and cockpit may not be acceptable as the sole means of keeping incompatible light from the cockpit if there are incompatible lights in the passenger cabin. Modifying the passenger cabin lighting with NVIS lighting would be recommended, due to the possibility of unacceptable light leaks, hot spots, and glare. Additionally, should a passenger or crewmember move the curtain, the glare and reflections could compromise pilot performance while using NVG.
(7) Exterior lighting. External lighting systems should not adversely affect the performance of the NVIS. The external lighting modifications must comply with §§ 29.1383 through 29.1401 and should use the guidance in AC 20-74. Evaluate external lighting under probable terrain, illumination, and environmental operating conditions. Non-NVIS position lights may cause unacceptable shadowing and interference with NVG performance in dark areas where there is little or no cultural lighting. NVIS-friendly position and anti-collision lights may be required. Landing lights and searchlights should be usable in the visible light mode. If a dual mode visible, IR landing, or searchlight is provided, the visible mode should be the default mode to allow the crew to more easily transition to unaided flight in case of NVG failures.
The crew should be able to illuminate landing zones sufficiently to allow unaided landing or obstacle identification and clearance in the event they need to transition to unaided operations .
(8) Reflections and glare. There should be no glare or reflections that interfere with unaided or NVG aided operations. Sources of reflection and glare could include aircraft interior surfaces (floor, Page MG 16-7
AC 29-2C, Chg 7 2/4/2016 panels, etc.), equipment, seats, etc. There must be demonstrated compliance with §§ 29.773, and
29.1381 in the ground and flight test.
(9) Controls.
(i) NVIS lighting controls should be readily identifiable and accessible.
(ii) NVIS control design should prevent the inadvertent selection of incompatible light sources in the cockpit. Typically, the use of a guarded or locking switch that does not allow inadvertently pushing of the switch to the incompatible light position is acceptable. If there is a capability to select an NVIS incompatible light source, the detrimental effects of incompatible light sources on the external view through the NVG should be evaluated. Some aircraft displays will power -up or re-boot in an NVG incompatible mode and require pilot action to select the NVG mode. This may be problematic should it interrupt power to a display in flight, and thus any possible effect on NVG performance should be evaluated.
(iii) NVIS lighting should have a dimming range consistent with aided and unaided operations.
Compliance with §§ 29.771(a), 29.773, 29.1301, 29.1309, and 29.1381 must be demonstrated. Lighting balance is important to assist in under-the-NVG scan. Native aircraft lighting may not have sufficient balance control to support NVG operations.
(iv) Some installations incorporate master light switches to control special busses for the lighting systems. If providing this capability, it should be evaluated to ensure failure modes are not introduced that will result in the illumination of incompatible light sources or loss of all required lighting.
(v) If IR lighting is installed in conjunction with the visible lighting systems required by §
29.1385, the control for the IR system should not turn the visible lighting system off when the IR system is activated.
(10) NVIS power sources. Determine whether the electrical power source capacity is adequate for the system installation under all foreseeable operating conditions including engine failure. Duplicate systems should be powered from separate busses and, in some cases, from independent sources if required by the airworthiness regulations (see §§ 29.1309 and 29.1351).
(11) NVIS cockpit and NVG integration.
(i) Accessibility and workload.
(A) The NVIS configuration should not compromise the ability to perform all necessary duties. Consider scanning and control accessibility. The applicant should determine the representative flight profiles and environmental conditions under which the workload should be evaluated. The purpose of this evaluation is to ensure that the workload associated with NVIS operations does not compromise safety of flight. It is important to assess the lighting system’s support of transition from aided flight to unaided flight. Demonstrate compliance with §§ 29.771, 29.773, 29.777, and 29.1523. Carefully consider the installation suitability for single pilot operation taking into account workload, cross cockpit view, and reduced field of view with the consequent need for greater head movement.
(B) If taking credit for the use of the landing light, this should be selectable and controllable without removing either hand from the primary flying controls.
(C) The design of the NVIS should consider flight into inadvertent IMC, unusual attitude recovery, and the transition from aided flight to instrument flight. This will also address the consequences of loss of external view through the NVG. Therefore, the applicant should plan this evaluation during all phases of aided flight (such as cruise flight or takeoff and landing, if requested) to ensure that workload is acceptable and the required instruments are within the pilot’s primary scan.
Page MG 16-8
( D) As sess the NVIS lighting for readability, uniformity, balance, light leakage, reflections, and degradation of NVG performance. See the NVIS and NVG cockpit integration checklists at http://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/nvis/. In addition, RTCA Document DO-275, section 4.0, provides an expanded explanation. Assess the cockpit using the make, model, and part number of the NVG that the applicant intends to show that are compatible with their NVIS lighting system.
(ii) Controls.
(A) Accessibility of NVIS lighting system controls. Pilots should be able to readily identify, access, and operate, with one hand, the NVIS lighting controls in-flight from their normal seated position.
(B) Inadvertent actuation of controls. Provide appropriate protection to prevent the inadvertent actuation of NVIS lighting controls and non-NVIS light sources.
(iii) Visibility.
(A) Windshield. The windshield and transparencies should not decrease NVG light sensitivities more than 12% (equivalent to one resolution element on a tri-bar chart). If the aircraft has a windshield anti-ice function, the visibility should be evaluated with anti-icing on and off to assess effect on the NVGs. Operation of windshield anti-ice should follow manufacturer’s procedures and limitations.
(B) Glare and reflectivity. Internal and external light sources can produce glare and reflectivity.
(C) Internal light sources.
(1) Reflections should be no worse than the original unaided lighting. However, NVGs may pick up more reflections than seen with unaided vision. Additionally, NVIS-incompatible light sources in other areas of the aircraft can cause interference. Block those reflections to ensure they do not interfere with the pilot’s ability to see outside the aircraft while wearing NVGs.
(2) Glare is an indication of an NVG-incompatible energy emission. Glare can result from poorly filtered or fitted lighting. Assess light sources causing glare and develop mitigating solutions to keep them from interfering with the pilots’ view through NVGs.
(D) External light sources.
(1) Assess external light glare and reflectivity during the night flight for both unaided and aided operations. Evaluating the effects of glare and reflecti ons that interfere with NVGs from external aircraft lighting is very important when operating in remote, dark areas. There are NVIS lighting position and anti-collision lights available. Consider using them if operations are conducted in very dark areas where there is little to no ambient cultural lighting.
(2) Methods to reduce glare or reflections caused by external aircraft lighting depend on where the light enters the cockpit and what aircraft structure reflects the light. For example, light that reflects off skids or wire cutters might be mitigated by using non-reflective paint on the reflecting surfaces.
If using physical barriers or baffle materials to block glare from entering the cockpit, pay particular attention to restrictions in the pilot's field-of-view through the chin bubble, particularly during take-off, landing, and hover operations. Also, pay attention to the potential of the mat or baffle moving or dislodging during flight, thereby causing interference with the tail rotor pedals or other aircraft controls.
(3) Use of blocking methods should be evaluated during both ground and flight test.
Note: It is possible that a non-compatible landing light used for NVG aided landings, which was found to be acceptable when landing on grass or a dark surface (e.g., asphalt), could cause unacceptable Page MG 16-9
AC 29-2C, Chg 7 2/4/2016 reflections when used over a light-colored concrete surface. For this reason, evaluate the effect of the light’s reflection off of various ground surfaces such as asphalt, concrete, etc., over which the aircraft may operate.
( ) Evaluate external light sources that pilots could use to assist them with NVG flight for their effect on NVG performance. Assess any installed landing lights, searchlights, etc., to determine their effect on the aide 4 d vi sual range. For instance, if the pilot uses a searchlight or landing lights to help assess a landing area or while landing with NVGs, then the light’s effect on the range of vision within and beyond the light boundaries should be evaluated and documented.
(5) During integration evaluations, record sources of non-compatible light glare and reflections and any mitigating strategies developed.
(12) Ground and flight tests.
(i) The purpose of FAA/AUTHORITY certification tests is to verify that the rotorcraft meets the certification requirements for both aided and unaided operations. Testing will include a ground and flight assessment of crew stations to ensure that the crew can use all systems for both aided and unaided operations. These assessments may result in changes to the limitations or operating procedures in the RFMS.
(ii) Prior to requesting FAA/AUTHORITY certification flight tests, the applicant should submit the certification plan, ground and flight test plans, and type design details (to include relevant data, drawings, bench tests, component tests, environmental qualifications, installation configurations, and test equipment and calibration) that were used to demonstrate compliance with the requirementsIt is highly recommended that the applicant and installer perform ground day, night, and NVG -aided evaluations prior to the FAA’s evaluations.
(iii) Ground and flight test plans should include the types of operations for which the applicant intends to use the aircraft. For instance, dual pilot operations or training will require both a right and left pilot seat evaluation. Emergency medical service (EMS) aircraft, for example, require an evaluation of visibility within the passenger compartment and the adequacy of cockpit protection from passenger compartment lighting if those lights are not NVG compatible.
(iv) The FAA/AUTHORITY will review the data package to verify compliance. After certification package acceptance, the applicant should coordinate the FAA/AUTHORITY ground and flight test plan and test schedule. The test plan and schedule should include all proposed tests to show compliance. RTCA Document DO-275, section 4.0, and its appendices describe one acceptable method of demonstrating compliance. The checklists found at http://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/nvis/ also outline another acceptable test sequence. Upon test plan acceptance, prior to commencing any certification tests (ground or flight), a conformity inspection should be performed. Once the conformity is completed, any changes from the conformed configuration (e.g., removing filters or changing bulbs in light sources) may require another conformity inspection at the discretion of the certification office.
(v) The applicant is responsible for meeting all pre-test requirements and providing the FAA/AUTHORITY certification office with the following:
(A) A list of test equipment the applicant will use (i.e., tri-bar charts, illumination source, illumination measuring device, NVG test set, or NVG eye lane).
(B) A description of the test facilities to be used (type of darkened location).
(C) A description of the proposed flight area including cultural lighting, terrain, obstacles, and landing areas.
Page MG 16-10
(D) Weather and illumination information including moon cycle, anticipated climatic conditions, etc.
(E) Any additional training necessary to operate in a NVIS environment (novel or new technology briefing).
(F) The flight equipment to be used (helmets, mounts, NVGs, flashlights, etc.).
(vi) Ground Test Procedures.
(A) Conducting ground testing prior to flight testing will optimize the test program and minimize flight test risks. Conduct this evaluation from all crew stations intended to be used (including the cabin) in NVG operations. The power supply used for ground tests, with the aircraft electrical generating system not operating, should provide power representative of flight conditions. Consider using power representative of flight conditions with generator and battery power to assess how the lighting system functions on low power.
(B) Flight-testing should be commenced after satisfactory completion of ground testing.
The schedule should allow for sufficient time between ground and flight test to resolve deficiencies discovered during ground testing. RTCA Document DO-275, section 4.4.1 and its appendices provide one acceptable test procedure and test sequence. Alternatively, as a minimum, complete the FAA Ground NVG-Cockpit Compatibility checklist, found at http://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/nvis.
(vii) Flight test procedures.
(A) Flight test should be scheduled for a low illumination (no moon) night, preferably in an area where there is little cultural lighting. Evaluation of NVG and NVIS lighting integration should be conducted in low ambient light conditions, because high ambient lighting conditions may mask the effects of inadequate cockpit lighting and reflections or glare.
(B) Prior to commencing the flight test evaluation, a daylight familiarization flight of the flight test area should be performed. Any specific flight regimes, maneuvers, terrain, or landing areas that will be used for the NVIS evaluation should be flown to familiarize the test pilots with possible hazards in the test area.
(C) Installing dual controls for every flight test evaluation is recommended, as additional risk-mitigation procedures may be required to conduct the test safely. If it is determined that the normal configuration of the aircraft is required for the flight evaluation, it may not be possible to install dual controls (such as, for example, in a police helicopter where the second crew station is equipped with comprehensive police mission systems). In this case, appropriate training and authorization may be required for the FAA/AUTHORITY test pilot to conduct the in-flight evaluation. The occupant of the second crew position should be a pilot trained in the use of NVGs and familiar with the installation under evaluation. In addition, special test equipment may be installed during the evaluation to enhance flight test safety. Minimum crew should be used to conduct an evaluation. If additional personnel are required for the evaluation, install the appropriate crew stations and safety equipm ent.
(D) The flight test profile should consist of maneuvers representative of those performed during normal or special operations over terrain and cultural areas in various illumination and weather conditions. This test should include evaluation under low illumination conditions (e.g., no moon, and overcast sky, with little cultural lighting). RTCA Document DO-275, section 4.4.2 provides one acceptable test procedure and test sequence. Alternatively, as a minimum, complete the NVIS-NVG Compatibility Flight Evaluation found at http://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/nvis.
g. Rotorcraft Flight Manual (RFM) (or Supplement (RFMS)).
Page MG 16-11
AC 2 9-2C, Chg 7 2/4/2016 An RFMS template is provided on the following pages.
Page MG 16-12
This section provides one acceptable template for use as a Rotorcraft Flight Manual Supplement (RFMS).
Other formats may be acceptable.
The following is an outline for a flight manual supplement to follow when developing a supplement for a specific STC. Information quoted in bold is expected to be in the RFMS verbatim. Following the headings are advisory and explanatory narratives in italics regarding the type of information you should include.
For example, under “2.1 NVG Compatibility, the explanatory text is not meant to be cut and pasted.
Note: Foreign civil certification authority requirements for flight manual supplement information will not be the same as represented here. If you are considering asking for a validation of your STC with, for example, EASA or TCCA, you may need to modify your RFMS. Coordinate with the appropriate foreign validation point of contact responsible for your project.
1. GENERAL. Include the following or similar statement:
“Any future modification, including role or mission specific equipment, involving a light emitting or reflecting device requires reassessment of the cockpit to ensure its compatibility with night vision imaging system (NVIS) operations.”
2. LIMITATIONS.
Add the following limitation if the aircraft has category A procedures and category A profiles were not certificated as part of the NVIS approval.
“Category A operations are prohibited when using NVG”
2.1 NVG Compatibility. The following NVGs are compatible with this cockpit lighting system: In this section, list the make and model of the NVGs used to determine compatibility. For example, if the STC holder shows its lighting system is compatible with ITT F4949 Class A and B NVGs, L- 3 M949, Class A and B NVGs, and Nivisys NVAG 6 NVGs, then the NVG compatibility list can be as follows.
2.1.1 NVGs that meet the performance requirements of TSO-C164. This covers NVG manufactured under a TSOA. 2.1.2 <Make, Model, and Part No. of NVG>. List the ITT/ExcelisF 4949 and Litton/Northrop-Grumman/L-3/Insight M949 NVG part numbers used to determine compatibility. If the STC is a foreign validation, coordinate with the validating authority to add foreign NVGs found compatible with the lighting system.
(NOTE: If the STC holder’s NVIS lighting system is shown to be only compatible with Class B NVGs, then add a limitation to use only Class B NVGs.)
2.2 Operational Limitations.
Include the following or similar limitation. This limitation may be different for RFMS’ acceptable by foreign authorities. Coordinate with the foreign authority for required wording:
“Installation of this NVIS lighting system does not approve flight operations with night vision goggles (NVG). The operator must coordinate with their FAA Flight Standards District Office to obtain operational authorization.”
2.3 Additional Required Equipment Functioning Correctly for NVG Operations (define this for each helicopter).
Page MG 16-13
AC 29-2C, Chg 7 2/4/2016
2.3.1 Vert ical speed indicator or equivalent.
2.3.2 List other aircraft equipment identified in the STC required for NVG operation like curtains separating the cockpit from the passenger cabin, chin bubble mats, etc.
If a design method (e.g., chin mats) is used to block the light from entering the cockpit, a caution such as the one below may be required. Only add requirements for chin mats or other light blocking items, like curtains, if they are required by the STC. Do not add generic statements or “if needed” statements to the limitations section of the RFMS.
“CAUTION:
Ensure <e nter chin mats, or whatever is used to block chin bubble light> are positioned and secured properly, allow sufficient view out of the chin bubble, and that they do not block or restrict operation of the flight controls.”
2.4 Minimum Crew. For foreign certifications, check with the foreign authority for correct wording.
2.4.1 Additional crewmember use of NVGs during single-pilot operations into and out of unimproved sites:
2.4.1.1 Landing. An additional NVG trained crewmember must be equipped with and use NVGs during landing to assist in obstacle identification and clearing.
2.4.1.2 Takeoff. An additional NVG trained crewmember must use NVGs during takeoff from unimproved sites to assist in obstacle identification and clearance if operational conditions permit (i.e., patient status allows).
2.5 Incompatible NVIS Lights. Specifically identify installed lighting in the cockpit and cabin that the STC did not modify and that are not useable during NVG operations. Additionally, include instructions on the use of non-NVIS lighting modified carry on equipment (e.g., cell phones, mission equipment, medical equipment) during NVG operations. For example, instructions should be the following or similar:
“Use of non-NVIS modified carry-on or personal equipment in the cockpit is prohibited during NVG operations”.
“The pilot must coordinate with other crewmembers and passengers before the use of non-NVIS modified carry-on equipment is used during NVG operations.”
3. EMERGENCY AND MALFUNCTION PROCEDURES.
3.1 NVG Malfunction or Failure. Describe procedures for NVG failure and for transition from aided to unaided flight, as may be required.
3.2 NVIS Lighting Malfunction or Failure in Flight. Describe procedures for handling NVIS lighting malfunctions, including procedures if the malfunction or failure degrades NVIS compatibility.
4. NORMAL PROCEDURES. Provide configuration and check procedures to ensure aircraft is capable of NVG operations. Suggested procedures are:
4.1 Operational Procedures.
4.1.1 Preflight.
• Check windshield, windows, and chin bubble windows for suitability (e.g., scratches, crazing, cleanliness).
Page MG 16-14
• Check filter condition for fogging, crazing, cracking, etc., which impairs unaided readability of the instrument or gauge to which the filter is applied.
• Check NVIS lighting for light leakage and compatibility.
• NVG adjustment and alignment.
• Check function of additional NVIS equipment.
• Interior configuration check for NVIS equipment (e.g., deselect incompatible light sources).
• Exterior configuration check for NVIS equipment (e.g., position lights, taxi and landing light, search light are selected to correct mode, if applicable).
• Adjust lighting as required.
4.1.2 In-flight.
• Control of cockpit and external NVIS illumination. Adjust lighting, as required.
• Transition to aided from unaided operations (and vice versa), as necessary.
• Radar altimeter and additional equipment procedures, as necessary.
4.1.3 Post flight. Report NVIS lighting or equipment and windscreen/transparency discrepancies.
5. WEIGHT AND BALANCE. The weight and balance should include the installation of NVIS equipment. Provide a sufficiently detailed system description. Refer to AC 43.13-1B, Chapter 10 for additional guidance.
(End of the section of one template for use as an RFMS.)
Page MG 16-15
AC 29-2C, Chg 7 2/4/2016
h. Instructions for Continued Airworthiness (ICA).
(1) General. ICA must contain the information necessary for carrying out ongoing maintenance and inspections on NVIS equipment installed in the rotorcraft. Refer to section AC 29.1529 and Appendix A of this guidance RTCA Document DO-275, section 5.5, also contains information related to the development of NVIS lighting ICA’s. . At a minimum, the following should be included:
(i) Appliance, system or accessory maintenance manual, or section.
(ii) Maintenance Instructions and Inspection Requirements. Ensure that the ICA instructions are clear on whether the operator must remove the filter or other NVIS modification prior to returning an instrument, gauge, or light to the manufacturer for maintenance. Ensure the ICAs have sufficient instructions on how to de-modify and re-modify instruments and gauges. Additionally, we recommend periodic inspections to ensure the NVIS lighting system is still NVG compatible and the configuration of the aircraft still agrees with the approved data. One acceptable method is the inclusion of an annual or time-interval inspection procedure..
(iii) Airworthiness Limitations.
(iv) Illustrated Parts Breakdown. The ICA should cover (as a minimum) aircraft transparencies (windscreen, windows, etc.), NVIS lighting, and any additional aircraft equipment that support NVIS operations. The NVG manufacturer should have ICA and maintenance schedules f or its goggles that the operator should follow.
It is recommended that a storage location or compartment is provided on the aircraft to protect the continued airworthiness of the NVGs. However, storing the NVGs in a location that could cause damage to the aircraft or an aircraft component, hinder crashworthiness, or result in loss of the intended function of a component is prohibited.
(2) Modifications or Maintenance.
(i) Post - Type Certificate (TC) or STC Approved Modifications. Any subsequent aircraft modifications (internal or external), including operational equipment (FLIR, EMS equipment, etc.)
involving a light emitting or reflecting device should be considered major since it could affect the operational characteristics of the NVIS lighting system and should be re-assessed against the original requirements for the NVIS certification.
(ii) Multiple TC or STC Approvals. If an approval is granted for multiple aircraft, installation and production procedures should ensure all aircraft comply with the type design. Provide this information in the initial certification data package so that the FAA knows it is intended for multiple approvals. The production procedures should be sufficiently detailed to detect minor differences between the different aircraft. Expect that post-production tests will include the ground and flight tests described above for each individual aircraft.
(iii) STC and Type Certificate Data Sheet (TCDS) verbiage: The following verbiage was developed to help with f.(2)(i) and f.(2)(ii) above and should be included in the “Limitations” section of the STC and the TC TCDS:
“Any deviation from the cockpit or cabin configuration specified in the STC or TC Type Design may affect the compatibility of the NVIS and will require a re-evaluation for NVIS cockpit and NVG compatibility. The aircraft is not certificated for NVG operations until the evaluation is completed.”
Note: Find the NVIS/NVG cockpit evaluation guides/checklists at http://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/nvis.
Page MG 16-16
CHAPTER 3
AIRWORTHINESS STANDARDS
TRANSPORT CATEGORY ROTORCRAFT
MISCELLANEOUS GUIDANCE (MG) AC 29 MG 17 GUIDANCE ON ANALYZING AN ADVANCED FLIGHT CONTROLS (AdFC) SYSTEM
a. Purpose.
(1) This MG provides certification guidance for installation of an AdFC system in rotorcraft. An AdFC is a flight control system that utilizes or replaces mechanical parts in conventional mechanical flight control systems with electronic parts such that there is no remaining direct mechanical link from the pilot to the control surfaces or swashplate.
Typical systems include fly-by-wire and fly-by-light. For the purpose of this document, conventional limited-authority or full-authority stability augmentation systems are not considered a subset of AdFC.
(2) This MG describes acceptable guidance for analyzing an AdFC system to determine compliance with all applicable sections of 14 CFR part 29. An applicant for a type certificate, amended type certificate, supplemental type certificate, amended supplemental type certificate, and technical standard order authorization may use the “Rotorcraft Advanced Flight Controls (AdFC) Handbook” (being published under Policy Statement PS-ASW-27,29-09), in conjunction with applicable ACs, to comply with relevant regulations.
b. References and Related Documents.
(1) Applicable 14 CFR part 29 regulations:
29.141, 29.143, 29.151, 29.161, 29.171, 29.173, 29.175, 29.177, 29.241,
29.391, 29.395, 29.397, 29.399, 29.602, 29.663, 29.671, 29.672, 29.674,
29.675, 29.681, 29.683, 29.685, 29.687, 29.771, 29.773, 29.777, 29.779,
29.1301, 29.1309, 29.1317, 29.1321, 29.1322, 29.1329, 29.1335, 29.1351,
29.1555, 29.1581, 29.1585, and Appendix B
(2) Applicable ACs (current version):
(i) AC 20-174, Development of Civil Aircraft and Systems.
(ii) AC 20-175, Controls for Flight Deck Systems.
(iii) AC 29-2, section 29.1309; Equipment, Systems, and Installations.
(3) Applicable Orders (current version):
Page MG 17 - 1
AC 29-2C, Chg 5 6/13/2014
(i) 4040.26, Aircraft Certification Service Flight Test Risk Management Program.
(ii) 8110.4, Type Certification.
(4) Applicable guidance:
(i) Policy Statement PS-ASW-27,29-09, Rotorcraft Advanced Flight Controls (AdFC) Handbook.
(ii) SAE, International ARP 4754A, Guidelines for Development of Civil Aircraft and Systems.
(iii) SAE, International ARP 4761, Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment.
c. Background. The FAA recognizes that technology utilized in commercial rotorcraft consistently lags behind state-of-the-art air transport aircraft and military technologies. AdFC technology has been in use for many years, but guidance material on the safety aspects of certification, continued operational safety, and especially the use of that technology has been limited within the FAA.
d. Application. Applicants seeking approval for the installation of an AdFC system in rotorcraft should apply this guidance as a means, but not the only means, for showing compliance with the applicable rules.
(1) Since part 29 regulations are inadequate for addressing the new and novel features of AdFC systems, special conditions, equivalent means of compliance, and methods of compliance issue papers may be required to establish safety standards in the following areas:
(i) Interaction of Systems and Structures. Since rotorcraft with AdFC systems may contain control functions that affect the structural integrity of the rotorcraft, additional safety considerations are necessary to address the effects of these systems on structural integrity, either directly or because of AdFC failures.
(ii) Pilot and Co-Pilot Dual Controls. Since the current regulations address mechanically linked controls only, additional safety considerations are necessary to address potentially confusing aspects of pilot and co-pilot dual, non-linked controls. As an example, a non-responsive control input could prevent compliance with § 29.779.
(iii) Lateral-Directional and Longitudinal Stability and Low Energy Awareness.
An AdFC allows for many possibilities in developing laws for novel flight control. In the simplest form, an AdFC could replace the function of a direct link between the flight controls and the swashplate. The current requirements were written with the conventional systems of the rotorcraft handling qualities in mind. A more likely situation Page MG 17 - 2