Note: For normal transitions from one AFCS mode to another, a single visual or aural alert may suffice. For an AFCS mode malfunction or a mode having a timecritical component, the flight crew alerting system must activate early enough to allow the flight crew to take timely and appropriate action. The alerting system means must be designed to alert the flight crew in order to minimize crew errors that could create an additional hazard.
(5) The reliability of the AFCS must be related to the effects of its failure. The occurrence of any failure condition that would prevent continued safe flight and landing must be extremely improbable. For any failure condition of the AFCS , which is not shown to be extremely improbable, the helicopter must be safely controllable and capable of continued safe flight without exceptional piloting skill, alertness, or strength. Additional unrelated probable failures affecting the control system must be evaluated. Additionally, the AFCS must be designed so that it cannot create a hazardous deviation in the flight path or produce hazardous loads on the helicopter during normal operation or in the event of a malfunction or failure, assuming corrective action begins within an appropriate period of time. Where multiple systems are installed, subsequent malfunction conditions must be evaluated in sequence unless their occurrence is shown to be improbable. A functional hazard assessment and a system safety assessment must be provided in accordance with section 29.1309 of this AC to address the failure conditions associated with the AFCS modes. The assessments must consider all systems required for AFCS mode operation, including the AFCS, all associated AFCS sensors (for example, radio altimeter), and primary flight displays. Electrical and electronic systems with catastrophic failure conditions (for example, AFCS) must comply with the § 29.1317(a)(4) High Intensity Radiated Field requirements.
(6) The AFCS modes must be demonstrated in the requested flight envelope.
(7) For any single failure or any combination of failures of the AFCS that is not shown to be extremely improbable, the recovery must not result in a loss of height greater than half of the minimum use height.
(8) For coupled flight below the previous VMINI, at the maximum demonstrated winds, the helicopter must be able to maintain any required flight condition and make a smooth transition from any flight condition to any other flight condition without requiring exceptional piloting skill, alertness, or strength, and without exceeding the limit load factor.
(9) For coupled flight below the previous VMINI, the following requirements of Appendix B to part 29 must be met and will be used as an extension to the IFR certification envelope of the basic aircraft:
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AC 29-2C, Chg 7 2/4/2016
(i) Static Longitudinal Stability: The requirements of Appendix B to part 27, paragraph IV are not applicable.
(ii) Static Lateral-Directional Stability: The requirements of Appendix B to part 27, paragraph V are not applicable.
(iii) Dynamic Stability: In lieu of the requirements of Appendix B to part 29, paragraph VI, the following apply:
(A) Any oscillation must be damped and any aperiodic response must not double in amplitude in less than 10 seconds. This requirement must also be met with degraded upper mode(s) of the AFCS.
(B) After any upset, such as a wind gust, the AFCS must return the aircraft to the last commanded position within 10 seconds or less.
(10) With any of the upper mode(s) of the AFCS engaged, the pilot must be able to manually recover the aircraft and transition to the normal (Appendix B to part 29) IFR flight profile envelope without exceptional skill, alertness, or strength.
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40 35 30 ~ I \, 0 w 25 (j) -0 0 f5 20
0..
15 I L 10 I
UNACCEPTABLE 5 -0.3 -0.2 -0.1 I' ' 0
DAMPING RATIO
ACCEPTABLE
0.05 0.1 0.15 2/4/2016 AC 29-2C, Chg 7 FIGURE AC 29 APX B-1 ROTORCRAFT DYNAMIC STABILITY
REQUIREMENTS FOR IFR Page Apdx B - 27
AC 29 APPENDIX B (AMENDMENT 29-59) AIRWORTHINESS GUIDANCE FOR ROTORCRAFT INSTRUMENT FLIGHT.
a. Explanation.
(3) Amendment 29-59 revised section VIII (b)(5)(i), which requires isolating the pilot instrument system from any other operating systems, to only apply to pneumatic systems. This change allows other types of pilot instrument systems to be connected to other systems on the rotorcraft and allows the use of modern technology to monitor and display highly integrated information. This guidance remains unchanged except paragraphs (b)(9)(v) and (b)(9)(vi) of this AC section do not apply to non-pneumatic systems.
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