powerplant overboost protection, buffet margin information, speed limits and control for each configuration of flaps, slats and landing gear, and airplane overspeed and underspeed protection. The performance management logic should provide protection against exceeding 250 knot IAS below 10,000 feet MSL, however pilot override of this feature should be provided.
(1) Ground Procedures. The flightcrew input data required to be manually entered into the computer will generally vary according to the number and types of output functions provided. These generally include airport ambient temperature, airplane zero fuel weight, flight distance, takeott flap osition, amount of thrust reduction, type of departure profile, etc. The arrangement of the display and the method of parameter input should lead the flightcrew in such a manner as to reduce the potential for human error. The display of the entered parameters should clearly identify the data units. The computer should contain reasonableness logic to prevent the airplane from being operated beyond its certificated envelope limits. This aspect will be unique for the airplane/engine combination. After the initialization procedures are complete, a means should be provided (pilot activated or automatic integrity check) to show that all the displays and interfaces with the autothrottles, flight directors, instrument bugs, etc., are functioning properly. This paragraph is applicable to all subsystems or functions contained in this AC.
(2) Takeoff Mode. The takeoff mode generally displays some or all of the takeoff speeds and appropriate engine thrust settings based upon the sensed or manually entered values of airport ambient temperature, airplane weight and thrust reduction as may be applicable. The following aspects should be considered in order to ensure that the takeoff performance is acceptable.
(i) Takeoff Autothrottle. The autothrottle servo configuration may impact the performance of the system when operating in some modes. Single servo systems have difficulty setting takeoff power on all engines since the first engine to reach the power commanded will stop the autothrottle advance which may leave the other engines low on power. Such a system would be usable only as an aid for setting takeoff power.
(ii) Engine Failure. The method of detecting an engine failure should be reviewed to establish the validity of the scheme. Low EGT sensing may not account for a slowly failing engine, or simulated failure during training. Automatic bleed-shut-off sensing may not account for Minimum Equipment List (MEL) items, etc. This type of review will aid in establishing the AFM limitations and procedures, and possible MEL revisions.
(iii) Takeoff Pitch Attitude. Some systems may derive and display an initial takeoft rotation pitch attitude based upon a predicted angle of attack and gradient without an actual angle of attack input. This method has been acceptable for initial pitch guidance only as this method does not account for less than predicted thrust, entered airplane weight too low,.
windshear, etc., which could lead to excessive pitch attitude. As a result, airspeed must be used as the primary reference and this should be clearly stated in the AFM.
Par 5 13
(iv) Engine-Out Flap Retraction. The FMS control laws should account for the available gradient and lower acceleration performance for an engine-out condition at each approved takeoff and climb flap/slat setting. As the flaps/slats are retracted to a new setting, the system should command a pitch attitude which results in the capture of the revised target speed at a reduced rate such that the airplane will maintain the minimum gradient required for that condition.
(v) Takeoff Speed Command Modes. Table 2 provides recommended transition and steady state tolerance criteria for low altitude autopilot or flight director speed command modes. The tolerance criteria is based upon normal flightcrew training and operational procedures and the consideration that the automatic system should command airplane performance which is commensurate to that which has been traditionally established for manual operation under the same conditions. Although the tolerance criteria is specified for still air, some allowance for local atmospheric conditions should be considered and a subjective evaluation should be made for this in atmospheric conditions which cause airplane upsets or disturbances to thade purpose. The demonstration of system pertormance, however.
extent that dynamic and steady state speed tracking performance cannot be readily determined.
(A) Takeoff. The system should provide commands that lead to the airplane smoothly acquiring a pitch attitude that results in a takeoff reference speed of 2+ X by the time the airplane has reached approximately 35 feet altitude. In the event of an engine failure during takeoff, the reference speed should be:
(1) V½ X for an engine failure at or above V½ + X.
(2) the time the airplane has reached approximately for an engine failure at or below V½. This speed should be attained by 35 feet altitude.
(3) Airspeed at engine failure for failure between V½ and V½ + X.
Note: X is the all-engine speed additive from the AFM which has generally been 10 knots or higher.
(B) Takeoff Noise Thrust Cutback. The system should provide commands that result in an indicated airspeed of V2 + X at all takeoff flap settings prior to thrust cutback. This speed should be maintained after thrust cutback even if the critical engine fails subsequent to the event.
Speed tolerances are provided in Table 2. Advisory Circular 91-53A, Noise Abatement Departure Profile, provides detail criteria concerning airplane flight profile, altitude, and thrust reduction constraints and the availability criteria for an automatic thrust advance feature. Handling qualities of a particular airplane may necessitate additional considerations for takeoff noise thrust cutback.
(C) Reduced Thrust Takeoff. Reduced thrust takeoffs are generally made for the purpose of reducing powerplant maintenance. Depending 14 Par 5
upon actual airplane takeoff weight, the thrust should be at least 75 percent of the takeoff thrust or derated takeoff thrust if such is the performance basis, for the existing ambient conditions. The assumed temperature method is commonly used for this purpose. In the event of the failure of the critical engine, the airplane will be able to maintain the minimum climb gradient required by the FAR without further advancing thrust on the remaining engines.
See AC 25-13, Reduced and Derated Takeoff Thrust (Power) Requirements, for specific guidance for this type of operation.
(D) Automatic Takeoff Thrust Control System. The FMS may provide automatic takeoff thrust control system (ATTCS) functions which will allow for reductions in takeoff thrust up to 10 percent of the takeoff thrust.
The ATTCS function is armed by the flightcrew and is designed to automatically advance the thrust on the remaining engine(s) to the takeoff thrust after an engine failure. Part 25, Appendix I contains the rules for ATTCS.
(E) Derated Takeoff Thrust. A derated takeoff thrust is a takeoff thrust less than the maximum takeoff thrust and for which a set of independent takeoff limitations and performance data may exist in the FMS computer memory. When this data is used for a derated takeoff, the thrust setting parameter which establishes thrust for takeoff, is considered a takeoff operating limit. Advisory Circular 25-13, Reduced and Derated Takeoff Thrust (Power) Requirements, provides certification guidance for this type of operation.
(F) Transition. The system should provide commands during periods of transition that are commensurate with that which would be expected from manual operation during the same condition. When speed deviations occur as the result of atmospheric conditions or delayed pilot response, corrective guidance should be provided that would minimize the time and magnitude of the deviation while being compatible with normal airplane maneuvering capabilities. The evaluation of this aspect is considered to be subjective and a qualitative assessment should be made during the flight demonstration.
(3) Climb Mode. The performance management function may provide a menu for manual or automatic selection of the climb speed schedule. This scheme ate or pude me for a selectable a tsped Machamber or fight path angle. The function may control the selection of climb thrust such as maximum climb thrust, fixed or variable derated thrust or a performance based derated thrust.
(4) Cruise Mode. The performance management function may control the selection of cruise altitude based upon such factors as minimum cost, fuel or time, maximum range or endurance or selected airspeed or Mach number. The system should compute a maximum altitude based upon buffet margin.
One-Engine-Inoperative Driftdown. The performance management function may control the driftdown with one engine inoperative.
This may be based upon the best estimate of engine and airplane performance using actual airplane sensor data.
Par 5 15
(ii) Two-Engine-Inoperative Driftdown. For airplanes with three or more engines, the performance management function may control the driftdown with two engines inoperative. This may be based upon the best estimate of engine and airplane performance using actual airplane sensor data.
(5) Descent Mode. The performance management function may select a descent schedule based upon minimum cost, tuel, time or a manually selected airspeed, Mach number or flight path angle. The computer should provide logic that would prevent the power being automatically reduced below safe levels or the minimum required when cescending with ice protection systems operating per AFM instructions.
(6) Landing Approach. The system should provide commands that result in an indicated airspeed of VREF + XX for all landing flap settings. This speed should be maintained even if the critical engine fails during stabilized approach.
Note: REF + XX is the landing approach reference speed plus the wind speed/gust additive, which may be manually entered.
(7) Landing Approach Go-Around. The airplane performance following addition of go-around thrust, during the landing approach go-around maneuver, with or without the simultaneous loss of an engine, should be such that the indicated airspeed is not reduced below that which existed upon initiation of the maneuver. The automatic and manual go-around procedures and speeds should be the same. The tolerances are specified in Table 2 and the go-around case assumes that the maneuver is initiated from stabilized approach.
(8) Annunciation and Display. The performance management primary flight modes selected by the fl ghtcrew such as takeoff, climb, cruise, descent and landing approach modes, should be displayed in the pilot's primary field of view. Performance management submodes such as reduced thrust takeoff, derated thrust takeoff and those modes providing automatic takeoff thrust control system functions should also be displayed but may be presented on the CDU. In addition, airplane performance information that was processed or computed by the FMS should be readily retrievable for display by the control display unit during any phase of the flight. Adequate annunciation should be provided for system or sensor failures which result in a loss or reduction of a performance management function. The central caution and warning system or other dedicated indicators may be used to annunciate some of the more significant performance management failure cases particularly when the FMS is extensively integrated with other airplane systems and sensors.
More routinely, a message light on the FMS control display unit may be used to alert the flightcrew to other system faults where immediate flightcrew action is not necessary. In this case, an indication should remain if a fault persists and another means such as a flashing message light should be provided to alert the flightcrew to further malfunctions.
system Accuracy. When the computed data is used as the primary reference for takeoff, landing approach, or command mode information, the resolution of the displayed data and the accuracy of the AFM curve fitting routines for performance parameters such as speed, engine thrust, and engine limit data should be equal to or better than those values which can be 16 Par 5
determined manually by the flightcrew when using the airplane performance information available on the flight deck. This criteria is commensurate with the methods used to establish the original type certificated performance of the airplane/engine combination. It is incumbent upon the applicant to provide the necessary documentation to the FAA to show that the computer memory contains authentic performance data for each airplane/engine combination for which the approval is sought. Table 1 provides generic guidance for representative computed and displayed performance parameters that are generally acceptable to the FAA.
Performance Management Integrity. With the exception of the takeoff and landing modes, the integrity required of computed airplane performance parameters generally depends upon the proposed use of the displayed information. When proposed as primary means, the flightcrew is not required to verify the validity of the displayed information with the airplane flight manual information. When proposed as advisory, the displayed information is supplemental to the AFM. Additionally, the integrity of a command system is established below for systems that compute and provide outputs that drive instrument indicators (bugs) or otherwise display a symbology for the purpose of directing the flightcrew to take an action that affects the performance or flight path of the airplane.
(i) Primary Information. The computation and display of hazardously misleading primary information such as takeoff V speeds, landing approach reference speeds, engine thrust, engine limit data or other related airplane performance data should be improbable. This includes system output data provided as a command mode for other instruments or displays. Flightcrew confirmation is required of all information that would be necessary to manually determine the same takeoff and landing performance data from the approved AFM performance charts prior to utilization by the FMS. An acceptable means of ensuring flightcrew conformation of these data is a key stroke for each required item. The computation and display of takeoff V, speed requires additional consideration in that the data required to compute this variable extends beyond normal airplane dependent parameters. Some systems may employ onboard airplane sensors to provide some of the airport, runway, and environmental data necessary for the computation of takeoff V, speed. When used as such, the onboard airplane sensor reliability must support the integrity criteria that has been specified above. Although the computed data is primary, approval does not negate the requirement for the flightcrew to have access to the airplane flight manual information on the flight deck.
(ii) Advisory Information. Takeoff and landing approach mode performance parameters are a special case in that they must meet the integrity criteria of paragraph 5e(10) (i) of this AC regardless of how the use of such computed data is proposed. Data computed for the climb, cruise and descent modes may be considered to be advisory and therefore do not have to meet the integrity criteria of paragraph 5f(10) (i) of this AC. These modes, however, should be shown to perform their intended function.
Automatic Takeoff Thrust Control System Failure Conditions. Some failure conditions involving the ATTCS takeoff mode function are major when considered independently and catastrophic when considered Par 5 17
coincident with the loss of an engine. For this purpose, the supporting inalysis may use the exposure time between takeoff decision speed minus one second (V,-1) and the airplane reaching an altitude of 400 ft AGL.
g. Autothrottle System (ATS). The FMS may incorporate a new ATS or utilize an existing system that has been modified for various flight modes.
In either case, the integration and compatibility of the ATS with the various flight management, performance management and autopilot modes must be taken into account.
NOTE: The criteria provided in this paragraph may not apply to turbo propellor or reciprocating engine powered airplanes. While the basic principals apply, the specific criteria may be different.
(1) Takeoff Mode. The ATS operates in a thrust control mode at high power settings and the system is designed to set the thrust by the time the throttle clamp speed is attained. A number of unique considerations apply to the takeoff mode.
(i) The ATS design should provide an autothrottle clamp (inhibit) speed during takeoff. The clamp speed should be the speed used during type certification for the determination of airplane performance and evaluation of engine limits. Subsequent minor throttle adjustments by the flightcrew may be required. If the designer chooses to select another speed for throttle clamp, one of the following should appily.
(A) The applicant may redemonstrate airplane performance and verify engine limit evaluations at the new clamp speed through climb to 400 ft. AGL.
The difference in performance between the selected clamp speed and the original performance related speed up to 400 feet AGL is negligible.
(ii) Adequate annunciation should be provided for the system failure condition where the throttles either fail to clamp at the takeoff inhibit speed or the throttles become unclamped during the takeoff mode below 400 ft. AGL.
(lil) Caution should be exercised in providing a single ATS servo clutch for all throttles for the takeoff mode. Since most systems control on the lead engine, throttle stagger may result in unacceptable thrust differential after throttle clamp.
(iv) Engine overboost and engine overspeed protection should be provided.
(v) Logic should be provided to account for flap, placard speeds.
(vi) Table 1 provides performance criteria for the ATS commanded parameters.
18 Par 5
(2) Climb Mode. The ATS may be selected to operate in either speed or thrust control modes. Since high power settings are normally used, overboost protection should be provided and may be required depending upon specific powerplant characteristics. The AlS logic should provide flight envelope speed protection based upon airplane configuration.
(3) Cruise Mode. The ATS may be selected to operate in either speed or thrust control modes. The system should be free of excessive throttle oscillations/hunting and it should be compatible with the autopilot pitch axis relative to speed on pitch/speed on throttles. Engine overboost, and flight envelope speed protection should be provided.
(4) Descent Mode The design should consider that a minimum thrust The ATS may be selected to operate in either speed or thrust control modes.
descent is compatible with minimum engine speed limits and cabin pressure altitude control and anti-ice bleed air requirements including accountability that the system may automatically switch from flight to ground idle if such a feature is provided. Flight envelope speed protection should be provided.
(5) Landing Approach Mode. The ATS may be selected for the speed or angle of attack control modes and the operating points may be set either manually or automatically. The system should be designed to control speed to within + 5 knots of the target speed but not less than the higher of VREF or
1.3V. of the landing contiquration. At the landing flare maneuver, the throttle retard rate should be consistent with the recommendations of the powerplant and airframe manufacturer.
(6) Go-Around Mode. In the FMS go-around mode, the ATS should operate in the thrust control mode. The system should automatically transition from the speed mode to the thrust control mode upon selection of the FMS go-around mode. The selection of the go-around mode may be a flight guidance function. The go-around thrust rating is usually selected manually by the flightcrew during landing approach; however, it may be automatically selected as a system feature. Actuation of the FMS go-around thrust rating selection may be independent of the go-around mode, however, when the goaround mode is actuated, the selection of the go-around thrust rating should be automatic.
Speed Floor Protection. If the system provides for pilot selection of speed, it should not be possible to select a speed below 1.2 Vsi Additional features may be provided by the ATS limiting the lowest speed that the system will command commensurate with the recommended minimum maneuvering speed for the airplane as a function of the maneuver being performed and the flap/slat position but not less than 1.2 Vsi. This protection may be provided by maximum angle of attack schedule.
(8) ATS Integrity. The autothrottle failure condition of uncommanded throttle movement between takeoff throttle clamp speed and 400 ft. AGL is considered major in accordance with AC 25.1309-1A and should be shown to be ' improbable. A slow throttle retard, such that pilot recognition of throttle movement would be in doubt in conjunction with an engine failure is considered catastrophic in accordance with AC 25.1309-1A, and should be shown to be extremely improbable. In this case, the cascade effect of engine failure, Par 5 19
electrical system disturbance and autothrottle system operation should be considered. Continuous unannunciated overboost is considered a major failure condition and should be shown to be improbable. Failure conditions of other modes of the ATS may be considered to be minor and may be probable.
Takeoff Performance Monitor. The FMS may provide the function of computing and displaying achieved airplane performance information to the flightcrew in real time. Airplane performance data derived from sensors is used to compute achieved performance. This data is compared to the computed airplane reference performance for the actual airplane configuration, weight, and takeoff thrust to be applied, and ai: port/runway environmental conditions such as temperature, wind and runway slope, and surface condition.
display of the computed data provides the flightcrew with additional information to assist in determining if the achieved airplane performance is acceptable.
(1) System Accuracy. The system displays information on the flightdeck so that the current status of the takeoff can be determined. It is important that system tolerances which can affect the accuracy of that flightdeck display be limited so that the presence of a significant deficiency in airplane performance will not be hidden nor will the display imply a significant performance deficiency when none exists. Therefore, the probability that the system tolerances will, of themselves, cause an error greater than + 5 percent in the apparent all-engine operating takeoff distance to rotation speed should be 0.01 or less. While this overall accuracy is the basic criteria, it is desirable that the accuracy of the individual performance parameter displays fall within the ranges as follows:
(1) Takeoff distance: ‡ 100 feet or + 2% (whichever is greater).
(ii) Airspeed: ‡ 4 knots or ‡ 2% (whichever is greater).
(iii) Longitudinal Acceleration: ‡ 0.2 feet per second squared or ‡ 2% (whichever is greater).
(2) Runway Considerations. If the time to a specific takeoff speed is computed and displayed, that speed should be sufficiently below decision speed to allow the flightcrew adequate time to decide if the difference between actual and computed performance is acceptable. The FAA feels that approximately 5 seconds is sufficient for this purpose. The computed time should agree with the airplane performance information developed in paragraph 5h(4) of this AC, to within 1 second. This accuracy criteria assumes near ideal runway conditions and if approval is sought for other conditions, the following considerations should be addressed in order to reduce the potential for unnecessary high speed rejected takeoffs.
(i) Runway Slope. Runways may have a constant or variable gradient and the accuracy of the airplane reference performance can be adversely affected. Runway gradient may be accounted for just as takeoff field length variables are accounted for. This may be satisfied with a flightcrew computer entry or by computer modeling or a combination of the two.
If the approval is sought for near constant gradient runways, the computer logic should account for the condition. If the runway has a variable 20 Par 5
gradient, the computer should contain a mathematical model of the condition and a means should be provided for the flightcrew to insert the data into the computer describing the point along the runway where the takeoff will be initiated. These considerations are not necessary for runways where the applicant can show that the computed reference performance can meet the accuracy criteria of paragraph 5h(1) of this AC.
Contaminated Runways. If the applicant seeks approval for operation on precipitation contaminated runways, the computer logic should account for the change in drag caused by standing water, slush, or snow.
Since, in some cases, there is a continuous variation of contamination along the length of a runway, accountability for such conditions may not be possible. The FAA has not developed criteria for the treatment of such conditions relative to takeoff performance monitors. It is the responsibility of the applicant to show that the performance criteria of paragraph 5h(1) of this AC is maintained for approval of system operation under such conditions.
The FAA will allow for an AFM limitation that prohibits the use of the system under these conditions at the applicant's discretion.
System Threshold. If the function is provided, the system should alert the flightcrew when the achieved performance is less than the reference performance by 5 percent. This alert should occur as early in the takeoff roll as possible as the field length and decision speed V, computations are based upon the manufacturers demonstrated values using known takeoff power and power application procedures. If the reference performance is less than that used for the computation, the runway distance used to reach V, will be greater and the corresponding length of remaining runway to decelerate and stop will be less.
(4) lakeott hrust. The implementation of the takeoff monitoring function should consider the manner in which the flightcrew will set thrust at the beginning of the takeoff roll. The thrust used for the AFM should be used for this purpose. Several models may be developed such as setting thrust statically or during a slight rolling takeoff, etc. If more than one model is developed, it may be a flightcrew selectable computer input. Airplane performance information should be developed that provides the same information as the computer model (s) so that it is available on the flight deck and the flightcrew can independently determine the computed airplane performance.
(5) Airmass Analysis. The applicant should perform airmass analysis to show the effects of a typical runway gust condition such as 10 knots/gust to 20 knots in order to show the suitability of the concepts used.
(6) Annunciation and Display. A real time digital or analog display of achieved and reference performance should be provided in the flightcrew's primary field of view. The nature of the display should be such that it provides information to the flightcrew as opposed to commanding a rejected takeoff or continued takeoff as in either case the final decision remains with the flightcrew. All forms of annunciation and display should be inhibited when the airplane reaches V, speed. If a display alerts the flightcrew that the system threshold of paragraph 5h(2) of this AC has been exceeded, it should be amber in color. It may also include an aural caution.
Par 5 21
(7) Function Integrity. Unannunciated system failure conditions are considered major in accordance with AC 25.1309-1A since the display of the computed data no matter how it is presented will influence the flightcrew's decision to continue the takeoff roll or initiate a rejected takeoff.
result, the computation and display of hazardously misleading information or the unannunciated loss of function should be improbable. The integrity of the external sensors should be considered. Computer software should be Level 2.
Fuel State. For each airplane model, the accuracy and resolution of the displayed fuel state computations should be equal to or better than that provided by the flight deck instrumentation approved at the time the original type certificate was issued.
(1) The FMS may utilize fuel and weight parameters in calculating airplane range and performance predictions which may be used in controlling the airplane. These predictions are calculated in real time and are continuously refined by the system throughout the flight. It also may utilize these inputs in arriving at engine out and drift down performance predictions, however the inputs should not be used as a basis for fuel load planning or airplane range predictions by the airplane operator.
(2) Fuel flow inputs from the airplane systems may be utilized by the FMS in order to refine airplane range and performance calculations.
(3) Fuel quantity may be used by the FMS and may be obtained directly from the airplane systems or entered into the system manually. These displays should not be substituted for the basic airplane fuel systems displays or gauges during airplane operation or fuel loading.
Fuel quantity low and fuel imbalance warnings may be incorporated into the FMS. Reserve fuel requirements may also be utilized by the FMS.
This input may be entered manually and may incorporate a low limit warning teature.
(5) Airplane gross weight and zero fuel weight may be used by the FMS and may be obtained directly from airplane systems or may be inserted manually. These parameters are the basis for all airplane performance calculations that are accomplished in real time.
(6) Fuel remaining at destination and fuel required for an alternate airport may be features incorporated into the FMS. Actual airplane range should not be based on these predictions.
j. Flight Deck Checklists. The FMS may provide additional features such as takeoff, landing and emergency flight deck checklists. These checklists may be displayed on the FMS control display unit, electronic flight instruments or by other means found acceptable to the FAA. Certification guidance is provided in AC 25-11, Transport Category Airplane Electronic Display Sys.ems.
k. Flight Management System Data Link. Airborne data links can be used by the FMS to provide a medium for the automated acquisition of flight plan navigational and airplane performance related data. The avionic functions 22 Par 5
which acquire and process such data should be developed and maintained to the criticality level of the processed data itself unless the applicant can show that a means can be provided to ensure that the integrity of the data is maintained. The imposition of an operational requirement for independent verification of such data by the flightcrew does not constitute an adequate means for this purpose, however, the data should not be used by the FMS until the data has been manually acknowledged by the flightcrew. An example of an airborne data link is the ARINC Communications, Addressing, and Reporting System commonly called ACARS.
Software Based Systems. An acceptable means for obtaining approval for the development of software based systems is to follow the design methodology contained in RTCA document DO-178A, Software Considerations in Airborne Systems and Equipment Certification, at the criticality level for which the approval is sought.
Software Changes. The provisions of this paragraph apply to FMS equipment which utilizes a digital computer to provide flight management information. The computer program (software) operates the computer and provides the basic functions of these systems. The software for navigation, performance management, autothrottle, and takeoff performance monitor Functions of the FMS equipment described in paragraphs 5e(7), 5f(10), 59(8), and 5h(7) of this AC should be verified and validated to at least the Level a requirements as defined by RTCA DO-178A. Any changes to software which affects these functions are considered to be major changes to the equipment.
software partitioning has been previously established, any change to Level 1 or Level 2 software of the FMS equipment should be verified and validated to the appropriate level and should be demonstrated as not having inadvertantly affected the remaining navigation, performance management, autothrottle, and takeoff performance monitor functions. Changes to software used for other FMS functions in equipment having established partitioning from software which provides navigation, performance management, autothrottle, and takeoff performance monitor functions, are considered to be minor and do not require prior approval by the FAA, providing the manufacturer of the FMS equipment has a software configuration management and quality assurance program approved by the FAA. All software changes should be identified in the outside of the associated line replaceable unit in accordance with the criteria of RTCA DO-178A. Software changes in TSO approved equipment must be reported to the cognizant Aircraft Certification Office. If the equipment displays a software identifier to the flightcrew, the AFM should indicate the approved identitier. Software changes incorporated in equipment already installed in an aircraft may require additional evaluation and possible flight manual revision prior to returning the aircraft to service, depending upon the scope of the change.
Software Identitier. If the FMS or its sensors are designed to display a software program identifier to the flightcrew, the progran identifier should be displayable by the FMS control display unit and the AFM should indicate the approved identifier.
Equipment Installation. An equipment installation failure modes and effects analysis should be provided, the extent of which is dependent upon the Par 5 23
degree of integration of the FMS with new or existing airplane systems and sensors.
n. Test and Evaluation.
Environmental Tests. The major components comprising the FMS should be qualified to the appropriate sections of RTCA document DO-160B, Environmental Conditions and Test Procedures for Airborne Equipment, or equivalent. The environmental qualifications should be compatible with the environment in which the equipment is installed.
from te intended function and that there are no adverse effects to existing airplane systems and sensors.
Simulators have been used extensively for evaluating the large matrix of FMS computed EPR, N1, engine overboost schedules, takeott and limits, etc. All of these parameters may vary with weight, altitude, an speed landing speed schedules, buttet boundary scnedules, YuM temperature, and in some cases engine bleed, center of gravity and load factor. Therefore, actual flight testing will at best provide only a small cross section of conditions that should be evaluated. The accuracy of the simulated inputs should be established by a validation program.
(ii) The thrust setting system (EPR or RPM) and airspeed/Mach system or Digital Air Data Computer system should be calibrated prior to the flight test evaluation.
(iii) Operational weight and balance records have been acceptable to use for flight test without the need for a dedicated weighing.
(3) Flight Tests. The applicant should provide a flight test plan that includes tests to verify that the FMS performs its intended function and that there are no adverse effects to other airplane systems and sensors.
These tests should include, but are not limited to the following:
(i) Flight test evaluations should be made to determine that prior approvals of existing airplane systems have not been compromised. This aspect could require extensive reevaluation it integration of the FMS required changes to existing airplane systems or sensors having prior approval tor automatic functions such as flight director takeoff, Category II or Category III landing modes.
(ii) Flight test evaluations should be made for all normal system operating modes such as speed command, attitude/thrust in combination with lateral and vertical navigation modes for takeoff, climb, cruise, descent and approach as may be applicable.
(iii) The advisory circulars which specify the flight test and evaluation requirements for navigation systems employing single or multisensor inputs are listed in paragraph 2b of this AC. If approval is sought for certain sub-(reversionary) operating modes utilizing single or a reduced Par 5 24