(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.
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(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
combination of sensor inputs, the evaluation must include an appropriate number of data points for each configuration for which the approval is sought.
The exact number of data points should be agreed upon between the applicant and the FAA and will depend upon the characteristics of the system.
(iv) The data obtained from the flight demonstration should be referenced to the flight deck instrumentation for airplane configuration and airspeed that the flightcrew normally uses to determine airplane performance when operating the airplane manually. Unless it can be shown that the type certificated airplane performance was determined in another manner, the data should not be corrected for actual flap/slat position or airspeed system position error.
(v) If the FMS approval is sought with mix of autopilot or autothrottle computers, each combination should be included during the evaluation.
(vi) The evaluation should include a sufficient number of
• simulated engine out conditions for the takeoff mode to demonstrate that the AFM engine out speed is smoothly captured and maintained. The effects of electrical transients upon the FMS due to the simulated loss of the engine and its associated generator should be assessed.
(vii) At least one actual engine shutdown should be accomplished to evaluate bus and/or generator load switching effects on the FMS. This test may be accomplished on the ground, provided there is nothing associated with flight logic that would invalidate such a simulation.
(viii) An FMS controlled buffet boundary protection margin should be demonstrated for all applicable flight modes by commanding a relatively large speed change at a point close to the boundary. Protection margin over or undershoot transients should not result in buffet.
(ix) The performance management climb, cruise and descent modes should also be evaluated during the flight test demonstration. Unlike the more critical takeoff, landing approach and go-around modes, the primary emphasis should be on the safety and operational characteristics of the speed schedules as opposed to the verification of the actual minimum cost, fuel or time schedules. The flight test should include a functional check of speed, fuel and time schedules as applicable. The operational suitability of these modes should also be evaluated. These modes should affect flightcrew workload and the ease and simplicity of their operation can impact the determination of the minimum flightcrew per § 25.1523.
(x) If an FMS approach autothrottle mode is provided, the control speed should be within + 5 knots of the programmed speed but not less than the computed threshold (minimum) speed. Reference Chapter 2, paragraph 11c(2) of AC 120-29, Criteria for Approving Category I and II Landing Minima for FAR 121 Operators. If the autothrottles are revised as a result of the FMS installation, a qualitative evaluation of Category II and/or autoland characteristics should be made if the airplane has been previously approved for such modes. If a new autothrottle is installed, a quantitative assessment may also be included in the evaluation.
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(xi) If the FMS is used to set power for takeoff by the use of coupled autothrottles, it should be demonstrated that the rate of power increase is sufficient to set the power prior to autothrottle clamp which generally occurs in the 60 to 80 knot range. This becomes increasingly important when operating at high performance conditions associated with light weight, low altitude, maximum takeoff power, and rolling takeoff procedure.
(xii) An evaluation of the fuel state computations should be made for reasonableness when compared with flight planning data.
(xiii) Installation of FNS that are heavily integrated into the airplane displays and controls may result in a change in pilot type rating for Contact should be made as early as possible with the Flight Standards Board for the particular airplane type in accordance with the details described in AC 61-XX, Procedures and Criteria for Determining the Type Rating Requirements for an Aircraft.
Airplane Flight Manual Supplement (AFMS). The AFMS should provide the appropriate system limitations and a comprehensive description of all normal and submodes of system operation including what actions are expected by the flightcrew for each case. A reduction in the amount of material covered may be allowed if the equipment manufacturer's pilot operating manual is required to be on board the aircraft and if the initial version and subsequent revisions are approved by the FAA. The following items, if applicable, should also be addressed in the AFMS.
(1) The compatibility of powerplant intermix and derate with the FMS performance management function.
(2) The AFMS should indicate those functions that have not been evaluated for accuracy by the FAA. The following is an example statement:
¿The accuracy of the FMS range and fuel management information have not been evaluated by the FAA; therefore, airplane range calculations and tuel management must not be predicted upon its use."
(3) The navigation functions, airspace and geographical areas approved for the FMS primary and/or sub-(reversionary) navigation modes should be clearly identified in the AFMS.
(4) The AFMS should describe how the FMS computed and displayed takeoff performance monitor information can vary as the result of varying wind conditions along the runway and the different techniques of applying thrust.
(5) Display of software identifier should be included in the AFMS.
LEROY A. KEITH Manager, Transport Airplane Directorate, Aircraft Certification Service, ANM-100 26 Par 5
Appendix 1 APPENDIX 1 TABLE 1
COMPUTED PERFORMANCE CRITERIA
PARAMETER COCKPIT FMS COMPUTES FMS ERRORS FMS CONTROLS
READABILITY TO THE AFM RESULTING FROM TO THE VALUES WITHIN: SENSOR ACCURACY COMPUTED
COMMANDS WITHIN (STEADY STATE*):
EPR .01 See Note 1 See Note 2 See Note 3 THRUST SET See Note 1 See Note 2 See Note 3 RPM (%) EGT (C) + 8 LIMITING 1 + 0, -1.0 + .5 + 1 RPM (%)
IAS (KTS) + 1 + 2 +5, -2 1 + 2, -0 + 2 @ 100 KTS +5, -0 T.O. & LDG 10 See Note 4 See Note 4 ...
DISTANCE (FEET) PERF See Note 5 See Note 5 See Note 5
LIMIT WT Dual systems displays may differ by the extremes of the sum of columns 3 and 4.
*Control accuracy on "steady state" basis; gusts and other short term disturbances may exceed these during transients.
NOTE 1: Computes thrust setting values to an accuracy that does not introduce appreciable error in the displayed value of the thrust setting parameter when compared to the value shown on the thrust setting charts contained in the AFM.
Typically ‡ .005 EPR or + .25% RPM.
NOTE 2: Errors introduced by sensor inaccuracy may not exceed those associated with the accuracies/readabilities historically deemed acceptable for the display of parameters used in setting thrust by means of reference charts contained in the AFM. Typically + .005 EPR or + .25% RPM.
NOTE 3: Controls all engines to computed commands with an accuracy equal to or better than the pilot's ability to set thrust manually without undue concentration or effort when relying on the thrust setting information sostans see paragraph sti21(1) of this Ac. 5% RPM. For single serve contained in the AFM. Typically NOTE 4: Not shorter than the distance determined by the AFM.
NOTE 5: Not greater than the weight determined from the AFM.