Source: https://www.federalregister.gov/documents/2005/04/12/05-7320/special-conditions-airbus-model-a380-800-airplane-dynamic-braking-interaction-of-systems-and
Timestamp: 2017-09-25 08:29:43
Document Index: 690901711

Matched Legal Cases: ['art 25', 'art 34', 'art 36', '§\u200925', '§\u200925', '§\u200925', '§\u200925', 'art 4', '§\u200925', 'art 25', 'art 25', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', 'art 25', 'art 25', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925', '§\u200925']

70 FR 19015
19015-19027 (13 pages)
Notice No. 25-05-04-SC
05-7320
11. Flight Envelope Protection High Speed Limiting
https://www.federalregister.gov/d/05-7320 https://www.federalregister.gov/d/05-7320
This notice proposes special conditions for the Airbus A380-800 airplane. This airplane will have novel or unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. These design features include side stick controllers, a body landing gear in addition to conventional wing and nose landing gears, electronic flight control systems, and flight envelope protection. These proposed special conditions also pertain to the effects of such novel or unusual design features, such as their effects on the structural performance of the airplane. Finally, the proposed special conditions pertain to the effects of certain conditions on these novel or unusual design features, such as the effects of high intensity radiated fields (HIRF) or of operation without normal electrical power. Additional special conditions will be issued for other novel or unusual design features of the Airbus A380-800 airplanes. A list is provided in the section of this document entitled “Discussion of Novel or Unusual Design Features.”
Comments on this proposal may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attention: Rules Docket (ANM-113), Docket No. NM305, 1601 Lind Avenue SW., Renton, Washington 98055-4056; or delivered in duplicate to the Transport Airplane Directorate at the above address. All comments must be marked: Docket No. NM305. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
Airbus applied for FAA certification/validation of the provisionally-designated Model A3XX-100 in its letter AI/L 810.0223/98, dated August 12, 1998, to the FAA. Application for certification by the Joint Aviation Authorities (JAA) of Europe had been made on January 16, 1998, reference AI/L 810.0019/98. In its letter to the FAA, Airbus requested an extension to the 5-year period for type certification in accordance with 14 CFR 21.17(c). The request was for an extension to a 7-year period, using the date of the initial application letter to the JAA as the reference date. The reason given by Airbus for the request for extension is related to the technical challenges, complexity, and the number of new and novel features on the airplane. On November 12, 1998, the Manager, Aircraft Engineering Division, AIR-100, granted Airbus' request for the 7-year period based on the date of application to the JAA.
In its letter AI/LE-A 828.0040/99 Issue 3, dated July 20, 2001, Airbus stated that its target date for type certification of the Model A380-800 has been moved from May 2005, to January 2006, in order to match the delivery date of the first production airplane. In accordance with 14 CFR 21.17(d)(2), Airbus chose a new application date of April 20, 1999, and requested that the 7-year certification period which had already been approved be continued. The part 25 certification basis for the Model A380-800 airplane was adjusted to reflect the new application date.
In addition to the applicable airworthiness regulations and special Start Printed Page 19016conditions, the Airbus Model A380-800 airplane must comply with the fuel vent and exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36. In addition, the FAA must issue a finding of regulatory adequacy pursuant to section 611 of Public Law 93-574, the “Noise Control Act of 1972.”
The Airbus A380-800 airplane will incorporate a number of novel or unusual design features. Because of rapid improvements in airplane technology, the applicable airworthiness regulations do not contain adequate or appropriate safety standards for these design features. The special conditions proposed for Airbus Model A380 contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
These proposed special conditions are identical or nearly identical to those previously required for type certification of the basic Model A340 airplane or earlier models. One exception is the special condition pertaining to Interaction of Systems and Structures. It was not required for the basic Model A340 but was required for type certification of the larger, heavier Model A340-500 and -600 airplanes.
In general, the proposed special conditions were derived initially from standardized requirements developed by the Aviation Rulemaking Advisory Committee (ARAC), comprised of representatives of the FAA, Europe's Joint Aviation Authorities (now replaced by the European Aviation Safety Agency), and industry. In some cases, a draft Notice of Proposed Rulemaking has been prepared but no final rule has yet been promulgated.
Additional special conditions will be issued for other novel or unusual design features of the Airbus Model A380-800 airplane. Those proposed special conditions pertain to the following topics:
Design roll maneuvers, and
Extendable length escape systems.
Due to the potential complexities of the A380 landing gear system, in addition to meeting the requirements of § 25.493(d), a rational analysis of the braked roll conditions is necessary. Airbus Model A340-500 and -600 also have a body-mounted main landing gear in addition to the wing and nose gears. Therefore, a special condition similar to that required for that model is appropriate for the model A380-800.
Previously, special conditions have been specified to require consideration of the effects of systems on structures. The special condition proposed for the Model A380 is nearly identical to that issued for the Model A340-500 and -600 series airplanes.
Like some other Airbus models, the Model A380 airplane is equipped with a side stick controller instead of a conventional control stick. This kind of controller is designed to be operated using only one hand. The requirement of § 25.397(c), which defines limit pilot forces and torques for conventional wheel or stick controls, is not appropriate for a side stick controller. Therefore, a special condition is necessary to specify the appropriate loading conditions for this kind of controller.
A special condition for side stick controllers has already been developed for the Airbus model A320 and A340 airplanes, both of which also have a side stick controller instead of a conventional control stick. The same special condition would be appropriate for the model A380 airplane.
In previous Airbus airplane certification programs, special conditions pertaining to side stick controllers were addressed in three separate issue papers, entitled “Pilot Strength,” “Pilot Coupling,” and “Pilot Control.” The resulting separate special conditions are combined in this special condition under the title of “Side Stick Controllers.” In order to harmonize with the JAA, the following has been added to Special Condition 4.c. Side Stick Controllers:
Airbus proposes to reduce the speed spread between VC and VD required by § 25.335(b), based on the incorporation of a high speed protection system in the A380 flight control laws. The A380—like the A320, A330, and A340—is equipped with a high speed protection system which limits nose down pilot Start Printed Page 19017authority at speeds above VC/MC and prevents the airplane from actually performing the maneuver required under § 25.335(b)(1).
Section 25.335(b)(1) is an analytical envelope condition which was originally adopted in Part 4b of the Civil Air Regulations to provide an acceptable speed margin between design cruise speed and design dive speed. Freedom from flutter and airframe design loads is affected by the design dive speed. While the initial condition for the upset specified in the rule is 1g level flight, protection is afforded for other inadvertent overspeed conditions as well. Section 25.335(b)(1) is intended as a conservative enveloping condition for all potential overspeed conditions, including non-symmetric ones. To establish that all potential overspeed conditions are enveloped, the applicant should demonstrate either of the following:
In lieu of compliance with the regulations pertaining to lateral-directional and longitudinal stability, this special condition ensures that the model A380 will have suitable airplane handling qualities throughout the normal flight envelope (reference paragraphs 6.a. and 6.b.).
The unique features of the A380 flight control system and side-stick controllers, when compared with conventional airplanes with wheel and column controllers, do not provide conventional awareness to the flight crew of a change in speed or a change in the direction of flight (reference paragraph 6.c.). This special condition requires that adequate awareness be provided to the pilot of a low energy state (low speed, low thrust, and low altitude) below normal operating speeds.
b. Longitudinal Static and Dynamic Stability: The longitudinal flight control laws for the A380 provide neutral static stability within the normal operational envelope. Therefore, the airplane design does not comply with the static longitudinal stability requirements of §§ 25.171, 25.173, and 25.175.
The pitch control movement of the side stick is a normal load factor or “g” command which results in an initial movement of the elevator surface to attain the commanded load factor. That movement is followed by integrated movement of the stabilizer and elevator to automatically trim the airplane to a neutral (1g) stick-free stability. The flight path commanded by the initial side stick input will remain stick-free until the pilot gives another command. This control function is applied during “normal” control law within the speed range from Vaprot (the speed at the angle of attack protection limit) to VMO to MMO. Once outside this speed range, the control laws introduce the conventional longitudinal static stability as described above.
With a response-command type of flight control system and no direct coupling from cockpit controller to control surface, such as on the A380, the pilot is not aware of the actual surface deflection position during flight maneuvers. Some unusual flight conditions, arising from atmospheric conditions or airplane or engine failures or both, may result in full or nearly full surface deflection. Unless the flight crew is made aware of excessive deflection or impending control surface deflection limiting, piloted or auto-flight system control of the airplane might be inadvertently continued in a way which would cause loss of control or other Start Printed Page 19018unsafe handling or performance characteristics.
This special condition requires that suitable annunciation be provided to the flight crew when a flight condition exists in which nearly full control surface deflection occurs. Suitability of such a display must take into account that some pilot-demanded maneuvers (e.g., rapid roll) are necessarily associated with intended full or nearly full control surface deflection. Therefore, simple alerting systems which would function in both intended or unexpected control-limiting situations must be properly balanced between needed crew awareness and not getting nuisance warnings.
This special condition and the method of compliance presented in Appendix 7 of the Flight Test Guide, AC 25-7A, provide a means by which one may evaluate flight characteristics—as, for example, “satisfactory,” “adequate,” or “controllable”—to determine compliance with the regulations. The HQRM in Appendix 7 was developed for airplanes with control systems having similar functions and is employed to aid in the evaluation of the following:
This special condition and the following ones—pertaining to flight envelope protection—present general limiting requirements for all the unique flight envelope protection features of the basic A380 Electronic Flight Control System (EFCS) design. Current regulations do not address these types of protection features. The general limiting requirements are necessary to ensure a smooth transition from normal flight to the protection mode and adequate maneuver capability. The general limiting requirements also ensure that the structural limits of the airplane are not exceeded. Furthermore, failure of the protection feature must not create hazardous flight conditions. Envelope protection parameters include angle of attack, normal load factor, bank angle, pitch angle, and speed. To accomplish these envelope protections, one or more significant changes occur in the EFCS control laws as the normal flight envelope limit is approached or exceeded.
Because Airbus has chosen to include this optional design feature for which part 25 does not contain adequate or appropriate safety standards, a proposed special condition pertaining to this feature is included. This special condition establishes minimum load factor requirements to ensure adequate maneuver capability during normal flight.
The longitudinal control law design of the A380 incorporates a high speed limiting protection system in the normal flight mode. This system prevents the pilot from inadvertently or intentionally exceeding the airplane maximum design speeds, VD/MD. Part 25 does not address such a system that would limit or modify flying qualities in the high speed region.
It restores positive static stability beyond VMO/MMO. Start Printed Page 19019
This special condition establishes requirements to ensure that pitch limiting functions do not impede normal maneuvering and that pitch and roll limiting functions do not restrict or prevent attaining certain roll angles necessary for emergency maneuvering.
Special conditions to supplement § 25.143 concerning pitch and roll limits were developed for the A320, A330 and A340 in which performance of the limiting functions was monitored throughout the flight test program. The FAA expects similar monitoring to take place during the A380 flight test program to substantiate the pitch and roll attitude limiting functions and the appropriateness of the chosen limits.
The A380 is equipped with a high incidence protection system that limits the angle of attack at which the airplane can be flown during normal low speed operation and that cannot be overridden by the flight crew. The application of this limitation on the angle of attack affects the longitudinal handling characteristics of the airplane, so that there is no need for the stall warning system during normal operation. In addition, the alpha-floor function automatically advances the throttles on the operating engines whenever the airplane angle of attack reaches a predetermined high value. This function is intended to provide increased climb capability. This special condition thus addresses the unique features of the low speed high incidence protection and the alpha-floor systems on the A380.
To ensure that a level of safety is achieved that is equivalent to that intended by the regulations incorporated by reference, a special condition is needed for the Airbus Model A380 airplane. This special condition requires that avionics/electronics and electrical systems that perform critical functions be designed and installed to preclude component damage and interruption.
These special conditions were developed to address fly-by-wire airplanes starting with the Airbus Model A330. As with earlier airplanes, the Airbus A380-800 fly-by-wire control system requires a continuous source of electrical power for the flight control system to remain operable.
To maintain the same level of safety as that associated with traditional designs, the Model A380 design must not be time limited in its operation, including being without the normal source of engine or Auxiliary Power Unit (APU) generated electrical power. Service experience has shown that the loss of all electrical power generated by the airplane's engine generators or APU is not extremely improbable. Thus, it must be demonstrated that the airplane Start Printed Page 19020can continue through safe flight and landing—including steering and braking on the ground for airplanes using steer/brake-by-wire—using its emergency electrical power systems. These emergency electrical power systems must be able to power loads that are essential for continued safe flight and landing.
In addition to the requirements of § 25.493(d), the following special condition applies:
Loads arising from the sudden application of maximum braking effort must be defined, taking into account the behavior of the braking system. Failure conditions of the braking system must be analyzed in accordance with the criteria specified in proposed special condition number 2, “Interaction of Systems and Structures.”
b. Unless shown to be extremely improbable, the airplane must be designed to withstand any forced structural vibration resulting from any failure, malfunction, or adverse condition in the flight control system. These loads must be treated in accordance with the requirements of paragraph a. above.
(1) General: The following criteria must be used for showing compliance with this special condition and with § 25.629 for airplanes equipped with flight control systems, autopilots, stability augmentation systems, load alleviation systems, flutter control systems, and fuel management systems. If this paragraph is used for other systems, it may be necessary to adapt the criteria to the specific system.
Probabilistic terms: The probabilistic terms (probable, improbable, and extremely improbable) used in this special condition are the same as those used in § 25.1309.
Failure condition: The term failure condition is the same as that used in § 25.1309. However, this special condition applies only to system failure conditions that affect the structural performance of the airplane (e.g., system failure conditions that induce loads, change the response of the airplane to inputs such as gusts or pilot actions, or lower flutter margins).
(c) System in the failure condition. For any system failure condition not Start Printed Page 19021shown to be extremely improbable, the following apply:
(ii) For residual strength substantiation, the airplane must be able to withstand two thirds of the ultimate loads defined in subparagraph (c)(1)(i) of this section.
(ii) For static strength substantiation, each part of the structure must be able to withstand the loads in subparagraph (2)(i) of this paragraph multiplied by a factor of safety, depending on the probability of being in this failure state. The factor of safety is defined in Figure 2.
Start Printed Page 19022
Q j = (Tj)(Pj)
(iii) For residual strength substantiation, the airplane must be able to withstand two thirds of the ultimate loads defined in subparagraph (c)(2)(ii).
(v) Freedom from aeroelastic instability must be shown up to a speed determined from Figure 3. Flutter clearance speeds V' and V” may be based on the speed limitation specified for the remainder of the flight, using the margins defined by § 25.629(b).
V' = Clearance speed as defined by § 25.629(b)(2).
V” = Clearance speed as defined by § 25.629(b)(1).
If Pj is greater than 10−3 per flight hour, then the flutter clearance speed must not be less than V”.
(vi) Freedom from aeroelastic instability must also be shown up to V' in Figure 3 above for any probable system failure condition combined with any damage required or selected for investigation by § 25.571(b).
(1) The system must be checked for failure conditions, not extremely improbable, that degrade the structural capability below the level required by part 25 or significantly reduce the reliability of the remaining system. The flight crew must be made aware of these failures before flight. Certain elements of the control system, such as Start Printed Page 19023mechanical and hydraulic components, may use special periodic inspections, and electronic components may use daily checks in lieu of warning systems to achieve the objective of this requirement. These certification maintenance requirements must be limited to components that are not readily detectable by normal warning systems and where service history shows that inspections will provide an adequate level of safety.
(2) The existence of any failure condition, not extremely improbable, during flight that could significantly affect the structural capability of the airplane and for which the associated reduction in airworthiness can be minimized by suitable flight limitations must be signaled to the flightcrew. For example, failure conditions that result in a factor of safety between the airplane strength and the loads of part 25, subpart C below 1.25 or flutter margins below V” must be signaled to the crew during flight.
(e) Dispatch with known failure conditions. If the airplane is to be dispatched in a known system failure condition that affects structural performance or affects the reliability of the remaining system to maintain structural performance, then the provisions of this special condition must be met for the dispatched condition and for subsequent failures. Flight limitations and expected operational limitations may be taken into account in establishing Qj as the combined probability of being in the dispatched failure condition and the subsequent failure condition for the safety margins in Figures 2 and 3. These limitations must be such that the probability of being in this combined failure state and then subsequently encountering limit load conditions is extremely improbable. No reduction in these safety margins is allowed, if the subsequent system failure rate is greater than 1E-3 per flight hour.
In addition to the requirements of § 25.397(c) the following special condition applies:
The limit pilot forces are as follows:
In the absence of specific requirements for side stick controllers, the following special condition applies:
c. Pilot control: It must be shown by flight tests that the use of side stick controllers does not produce unsuitable pilot-in-the-loop control characteristics when considering precision path control/ tasks and turbulence. In addition, pitch and roll control force and displacement sensitivity must be compatible, so that normal inputs on one control axis will not cause significant unintentional inputs on the other.
In lieu of the requirements of § 25.335(b)(1)—if the flight control system includes functions which act automatically to initiate recovery before the end of the 20 second period specified in § 25.335(b)(1)—the greater of the speeds resulting from the following special condition applies.
a. From an initial condition of stabilized flight at VC/MC, the airplane is upset so as to take up a new flight path 7.5 degrees below the initial path. Control application, up to full authority, is made to maintain this new flight path. Twenty seconds after initiating the upset, manual recovery is made at a load factor of 1.5 g (0.5 acceleration increment) or such greater load factor that is automatically applied by the system with the pilot's pitch control neutral. The speed increase occurring in this maneuver may be calculated, if reliable or conservative aerodynamic data is used. Power, as specified in § 25.175(b)(1)(iv), is assumed until recovery is made, at which time power reduction and the use of pilot controlled drag devices may be used.
(3) no dispatch of the airplane is allowed with the system inoperative. Start Printed Page 19024
In lieu of the requirements of § 25.171 and sub-section 25.177(c), the following special condition applies:
a. The airplane must be shown to have suitable static lateral, directional, and longitudinal stability in any condition normally encountered in service, including the effects of atmospheric disturbance.
b. The airplane must provide adequate awareness to the pilot of a low energy (low speed/low thrust/low height) state when fitted with flight control laws presenting neutral longitudinal stability significantly below the normal operating speeds.
In addition to the requirements of §§ 25.143, 25.671 and 25.672, the following special condition applies:
a. General Limiting Requirements: (1) Onset characteristics of each envelope protection feature must be smooth, appropriate to the phase of flight and type of maneuver, and not in conflict with the ability of the pilot to satisfactorily change the airplane flight path, speed, or attitude, as needed.
In addition to the requirements of 25.143(a)—and in the absence of other limiting factors—the following special condition applies:
This Special Condition does not impose an upper bound for the normal load factor limit, nor does it require that the limit exist. If the limit is set at a value beyond the structural design limit maneuvering load factor “n,” indicated in § 25.333(b) and 25.337(b) and (c), there should be a very positive tactile feel built into the controller Start Printed Page 19025and obvious to the pilot that serves as a deterrent to inadvertently exceeding the structural limit.
High Incidence Protection System. A system that operates directly and automatically on the airplane's flying controls to limit the maximum angle of attack that can be attained to a value below that at which an aerodynamic stall would occur.
Vmin The minimum steady flight speed is the stabilized, calibrated airspeed obtained when the airplane is decelerated at an entry rate not exceeding 1 knot per second, until the longitudinal pilot control is on its stop with the high incidence protection system operating.
Vmin1gVmin corrected to 1g conditions. It is the minimum calibrated airspeed at which the airplane can develop a lift force normal to the flight path and equal to its weight when at an angle of attack not greater than that determined for Vmin.
b. Capability and Reliability of the High Incidence Protection System:
(1) It must not be possible to encounter a stall during pilot induced maneuvers, and handling characteristics must be acceptable, as required by Paragraphs e and f below, entitled High Incidence Handling Demonstrations and High Incidence Handling Characteristics respectively.
c. Minimum Steady Flight Speed and Reference Stall Speed:
In lieu of the requirements of § 25.103, the following special condition applies:
(1) Vmin The minimum steady flight speed, for the airplane configuration under consideration and with the high incidence protection system operating, is the final stabilized calibrated airspeed obtained when the airplane is decelerated at an entry rate not exceeding 1 knot per second until the longitudinal pilot control is on its stop.
nz w = load factor normal to the flight path at Vmin
is first a maximum during the maneuver prescribed in paragraph (5)(h) of this section.
(h) Starting from the stabilized trim condition, apply the longitudinal control to decelerate the airplane so that Start Printed Page 19026the speed reduction does not exceed one knot per second.
d. Stall Warning. (1) Normal Operation: If the conditions of Paragraph b above which is entitled Capability and Reliability of the High Incidence Protection System are satisfied, a level of safety equivalent to that intended by § 25.207, Stall Warning, must be considered to have been met without provision of an additional, unique warning device.
(2) Failure Cases: Following failures of the high incidence protection system not shown to be extremely improbable, if the system no longer satisfies sub paragraphs (1), (2), and (3) of Paragraph b above which is entitled Capability and Reliability of the High Incidence Protection System, stall warning must be provided in accordance with § 25.207. The stall warning should prevent inadvertent stall under the following conditions:
e. High Incidence Handling Demonstrations: In lieu of the requirements of § 25.201, the following special condition applies:
(7) Starting at a speed sufficiently above the minimum steady flight speed to ensure that a steady rate of speed reduction can be established, apply the longitudinal control so that the speed reduction does not exceed one knot per second until the control reaches the stop.
(8) The longitudinal control must be maintained at the stop until the airplane has reached a stabilized flight condition and must then be recovered by normal recovery techniques.
(9) The requirements for turning flight maneuver demonstrations must also be met with accelerated rates of entry to the incidence limit, up to the maximum rate achievable.
f. High Incidence Handling Characteristics: In lieu of the requirements of § 25.203, the following special condition applies:
(1) Throughout maneuvers with a rate of deceleration of not more than 1 knot per second, both in straight flight and in 30 degree banked turns, the airplane's characteristics must be as follows:
(2) In maneuvers with increased rates of deceleration, some degradation of characteristics is acceptable, associated with a transient excursion beyond the stabilized alpha-limit. However, the airplane must not exhibit dangerous characteristics or characteristics that would deter the pilot from holding the longitudinal controller on the stop for a period of time appropriate to the maneuvers.
(3) It must always be possible to reduce incidence by conventional use of the controller.
(4) The rate at which the airplane can be maneuvered from trim speeds associated with scheduled operating speeds such as V2 and VREF up to alpha-limit must not be unduly damped or significantly slower than can be achieved on conventionally controlled transport airplanes.
g. Atmospheric Disturbances: Operation of the high incidence protection system and the alpha-floor system must not adversely affect aircraft control during expected levels of atmospheric disturbances or impede the application of recovery procedures in case of windshear. Simulator tests and analysis may be used to evaluate such conditions but must be validated by limited flight testing to confirm handling qualities at critical loading conditions.
h. Alpha Floor: The alpha-floor setting must be such that the aircraft can be flown at normal landing operational speed and maneuvered up to bank angles consistent with the flight phase, including the maneuver capabilities specified in 25.143(g), without triggering alpha-floor. In addition, there must be no alpha-floor triggering, unless appropriate, when the airplane is flown in usual operational maneuvers and in turbulence.
i. Proof of Compliance: In addition to the requirements of § 25.21, the following special condition applies:
j. Longitudinal Control: (1) In lieu of the requirements of § 25.145(a) and 25.145(a)(1), the following special condition applies:
It must be possible—at any point between the trim speed for straight flight achievable by the automatic trim system and Vmin—to pitch the nose downward, so that the acceleration to this selected trim speed is prompt, with the airplane trimmed for straight flight at the speed achievable by the automatic trim system.
(2) In lieu of the requirements of § 25.145(b)(6), the following special condition applies:
With power off, flaps extended and the airplane trimmed at 1.3 VSR1, obtain and maintain airspeeds between Vmin and either 1.6 VSR1 or VFE, whichever is lower. Start Printed Page 19027
k. Airspeed Indicating System: (1) In lieu of the requirements of subsection 25.1323(c)(1), the following special condition applies:
(2) In lieu of the requirements of subsection 25.1323(c)(2), the following special condition applies:
a. Protection from Unwanted Effects of High-intensity Radiated Fields:
Each electrical and electronic system which performs critical functions must be designed and installed to ensure that the operation and operational capabilities of these systems to perform critical functions are not adversely affected when the airplane is exposed to high intensity radiated fields external to the airplane.
b. For the purposes of this special condition, the following definition applies:
Critical Functions: Functions whose failure would contribute to or cause a failure condition which would prevent the continued safe flight and landing of the airplane.
Issued in Renton, Washington, on March 29, 2005.
[FR Doc. 05-7320 Filed 4-11-05; 8:45 am]