AC 25-7D

Appendix D

(b) No airplane shall be taken off at a weight such that, allowing for normal consumption of fuel and oil in flight to the airport of destination and to the alternate airports, the weight on arrival will exceed the landing weight specified in the AFM for the elevation of each of the airports involved and for the ambient temperatures anticipated at the time of landing. (See secs. 4T.123(a) (2) and 4T.743(a).)

(c) No airplane shall be taken off at a weight which exceeds the weight at which, in accordance with the minimum distances for takeoff scheduled in the AFM, compliance with subparagraphs (1) through (3) of this paragraph is shown. These distances shall correspond with the elevation of the airport, the runway to be used, the effective runway gradient, and the ambient temperature and wind component existing at the time of takeoff. (See secs. 4T.123(a)(3) and 4T.734(a).)

(1) The accelerate-stop distance shall not be greater than the length of the runway plus the length of the stopway if present.

(2) The takeoff distance shall not be greate r than the length of the runway plus the length of the clearway if present, except that the length of the clearway shall not be greater than one-half of the length of the runway.

(3) The takeoff run shall not be grea ter than the length of the runway.

(d) No airplane shall be operated outside th e operational limits specified in the AFM.

(See secs. 4T.123(a)(4) and 4T.743(a).)

5. The following definitions shall apply:

(a) Clearway. A clearway is an area beyond the runway, not less than 500 feet wide, centrally located about the extended centerline of the runway, and under the control of the airport authorities. The clearway is expressed in terms of a clearway plane, extending from the end of the runway with an upward slope not exceeding 1.25 percent, above which no object nor any portion of the terrain protrudes, except that threshold lights may protrude above the plane if their height above the end of the runway is not greater than 26 inches and if they are located to each side of the runway.

NOTE: For the purpose of establishing takeoff distances and takeoff runs, in accordance with section 4T.117 of this regulation, the clearway plane is considered to be the takeoff surface.

(b) Stopway. A stopway is an area beyond the runway, not less in width than the width of the runway, centrally located about the extended centerline of the runway, and designated by the airport authorities for use in decelerating the airplane during an aborted takeoff: To be considered as such, a stopway must be capable of supporting the airplane during an aborted takeoff without inducing structural damage to the airplane. (See also sec. 4T.115(d) of this regulation.)

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Appendix E APPENDIX E. FAA HANDLING QUALITIES RATING METHOD E.1 Explanation.

Many of the stability and control requirements of part 25 are inadequate or unsuitable safety standards for airplanes with electronic flight control systems (EFCS) because these systems use control laws to define or augment the airplane’s natural handling qualities. As a result, the handling qualities rating method (HQRM) was developed to provide a systematic way to determine appropriate minimum handling qualities requirements that take into account the features, characteristics, and limitations of an EFCS. The HQRM defines the minimum acceptable handling characteristics as a function of the atmospheric conditions, flight envelope conditions, piloting task, and probability of the particular failure condition being evaluated. The pilot rating levels used in this HQRM may also be useful in evaluating flying qualities for showing compliance with existing part 25 requirements where the airplane must be shown to be capable of continued safe flight and landing. Unless otherwise specified in a special condition, the HQRM does not replace or override any of the systems and equipment requirements of §§ 25.1301 and 25.1309 or the control system requirements of §§ 25.671 and 25.672.

E.2 Procedures.

E.2.1 The HQRM is a pilot task-oriented approach for evaluating airplane handling qualities.

E.2.2 The HQRM uses a probability of occurrence versus safety effect philosophy in relating the minimum acceptable handling qualities to the probability of being in a particular portion of the airplane’s flight envelope (referred to as Xe), the probability of encountering certain atmospheric disturbance levels (referred to as Xa), and the probability of a specific flight control failure state (referred to as Xc). The overall process used for the HQRM is shown in figure E-1.

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AC 25-7D Appendix E Figure E-1. Overall HQRM Process

E.2.3 Handling qualities to perform a specified pilot task for a particular flight condition are expressed in terms of one of three levels: Satisfactory (SAT), Adequate (ADQ), and Controllable (CON). A description of these handling qualities ratings is presented in table E-1 below, along with the equivalent Cooper-Harper and Military Standard ratings for comparison. The handling qualities rating will be used to determine if the handling qualities of a specific test condition are acceptable, considering the probabilities of the failure state being evaluated (Xc), being in a particular portion of the flight envelope (Xe), and the atmospheric disturbance level (Xa).

Table E-1. Comparison of Handling Qualities Ratings

FAA Handling Qualities (HQ) Cooper- Military Standard HQ Rating Definition Harper Rating Level Quality Satisfactory (SAT) Full performance criteria met with routine pilot effort and attention. 1-3 1 SAT Adequate (ADQ) Adequate for continued safe flight and landing. Full or specified reduced performance met, but with heightened pilot effort and attention.

4-6 2 ACCEPT Controllable (CON) Inadequate for continued safe flight and landing, but controllable for return to a safe flight condition, a safe flight envelope, and/or allows a reconfiguration that provides HQ that are at least ADEQUATE.

7-8 3 CON E-2

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AC 25-7D Appendix E E.2.4 The HQRM should be used to evaluate airplane handling qualities while performing typical static and dynamic maneuvers. A sample list of such tasks is presented in figure E-2. Task performance criteria should be defined for each identified task. From a test execution perspective, test tasks with criteria are defined (which may include a failure state, region of the flight envelope, and/or atmospheric condition), the tasks are flown and ratings are determined (from the HQRM rating scale shown in table E-1) for each task as flown. If desired, the Cooper Harper Handling Qualities Rating Scale can be used along with table E-1 to determine HQRM ratings for a given task.

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Appendix E Figure E-2. Sample Tasks for Evaluating Airplane Handling Qualities

A. Trim and Unattended Operation Characteristics of the airplane to stay at or depart from an initial trim or unaccelerated condition.

 Dynamic and steady-state flight path response to pulse input (all 3 axes).

 Dynamic and steady-state flight path response to atmospheric disturbance.

 Spiral stability (e.g., release controls at 40 bank).

B. Large Amplitude Maneuvering Generally, these are open-loop maneuvers in which the pilot attempts a significant change in airplane path, speed, or attitude in order to evaluate safe airplane capability that are beyond those expected in normal operational service. Maneuvers may be initiated outside the Normal Flight Envelope and transition flight envelopes. Most of these maneuvers are representative of airworthiness stability and control tests.

Pitch/Longitudinal  Wind-up turn or symmetric pull-up/push-over.

 Slow-down turn at fixed g or on AOA or g-limiter.

 Stall or AOA-limiter approach.

 Push-pull off trim speed.

Roll  Rapid bank-to-bank roll.

Yaw  Sudden heading change.

 Constant heading sideslip.

Operational  Pitch/roll upset recover.

 Emergency descent.

 Climbing/diving turn.

 Takeoff/land windshear escape maneuver.

 Takeoff/land windshear escape maneuver—Go around/power or thrust application from low speed.

 Arrest of high sink rate, at touchdown or level-off altitude.

 Collision avoidance roll/pull.

 Takeoff and landing flare with underspeed or high crosswind.

C. Closed-Loop Precision Regulation of Flight Path Generally, these are tightly-bounded, pilot closed-loop tasks expected to be performed in routine commercial flight. These controlling tasks are almost exclusively within the Normal Flight Envelope, or not far outside the NFE boundary.

 ILS and precision touchdown, various atmospheric disturbance and initial offset.

 Formation flying (as simulator for maneuver tracking).

SPD/ALT/HDG tracking, in various atmospheric disturbance and cockpit display status, for:

 Takeoff.  Climb.

 Cruise.  Descent.

 Hold.

 Configuration changes/power or thrust changes.

 Transition between the aforementioned.

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Appendix E E.2.5 Figure E-3 provides guidance for determining the probability of occurrence associated with being in a particular portion of the flight envelope (Xe), in a particular atmospheric disturbance level (Xa), and with a particular flight control failure state (Xc). It also describes how the flight envelope probability (Xe) should be modified for interrelationships with the atmospheric condition.

Figure E-3. Probability of Occurrence Guidelines

A. Flight Envelope (Xe) Probability of occurrence (at flight envelope boundary) Normal Flight Envelope Generally associated with routine operational and/or prescribed conditions, either all engines operating or one engine inoperative.

100 Operational Flight Envelope Generally associated with warning onset; outside the normal flight envelope.

10-3 Limit Flight Envelope Generally associated with airplane design limits or EFCS protection limits.

10-5 Refer to this figure and figures E-4 and E-5 for more detail on determining which flight envelope is applicable.

It may be necessary to consider several of the pertinent flight parameters together to determine which flight envelope a given flight condition is in. For the more influential flight parameters, such as angleof-attack (AOA), speed, and load factor normal to the flight path (Nz), the choice of which flight envelope a condition is in may be determined by as few as one of the parameter values. Since the flight envelopes cover ranges of parameters (e.g., for Flaps UP, Nz in the LFE can be from 1.6 to 2.5), the above target probabilities for OFE and LFE might vary slightly depending on the expected airplane behavior and the assigned task.

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AC 25-7D Appendix E Figure E-3. Probability of Occurrence Guidelines (continued)

B. Atmospheric Disturbance Level Probability of occurrence (at flight envelope boundary) Light: Turbulence that momentarily causes slight, erratic changes in altitude and/ or attitude (pitch, roll, yaw). Crosswinds up to 10 knots.

100 Moderate: Turbulence that is similar to light turbulence, but of greater intensity. Changes in altitude and/or attitude occur. Usually causes variations in indicated airspeed. Crosswinds up to 25 knots.

10-3 Severe: Turbulence that causes large, abrupt deviations in altitude and/or attitude. Usually causes large variations in indicated airspeeds.

Crosswinds substantially in excess of the minimum required crosswind to be demonstrated safe for takeoff and landing.

10-5 C. Flight Control System Failure State Probability of occurrence (at flight envelope boundary) 100 Normal Operation:

100 - 10-5 Probable Failures:

10-5 - 10-9 Improbable Failures:

D. Modifying the Flight Envelope Probability for Interrelationships with Atmospheric Conditions The above probability of occurrence values apply when considered separately. When obvious interrelationships exist due to the design or the intended or expected operation of the airplane, the way to address this within HQRM is to modify the flight envelope probability value. For example, a severe windshear event may result in a flight envelope probability of 100, not 10-3 or 10-5 as shown above for the OFE or LFE, since the operational procedure for escape would be to pull toward the AOA limit in windshear. Similarly, an airplane may experience overspeed, from VMO cruise, into the OFE due to a gust, in which case the modified flight envelope probability would be 100, not 10-3 . This probability adjustment concept would also apply to EFCS failure cases where, for example, loss of warnings or exposure to reduced airplane stability might contribute to excursions outside the normal flight envelope (NFE) or OFE, in which case the flight envelope probability should be appropriately increased.

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AC 25-7D Appendix E E.2.6 Three different flight envelopes (or portions of the airplane’s flight envelope), called the normal, operational, and limit flight envelopes have been defined as a function of various flight parameters. These flight envelopes are shown for flaps up and flaps down configurations in figures E-4 and E-5, respectively.

Figure E-4. Flaps UP Flight Envelopes

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AC 25-7D Appendix E Figure E-5. Flaps DOWN Flight Envelopes

E.2.7 Figure E-6 presents the method for combining the various flight condition parameter probabilities to determine the minimum acceptable handling qualities rating for each combination of these parameters. This method is shown graphically in Figure E-7.

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Appendix E Figure E-6. Combining Values

A. Analyze Failures/Determine Flight Control System Failure Probability (Xc).

 Predicted failure rates/check failure co-dependence  Equipment Inoperative Dispatch under MEL  Service Difficulty Records (continuing airworthiness) B. Determine Flight Envelope Probabilities (Xe) and Atmospheric Probabilities (Xa) for the Flight Condition.

C. Modify the Flight Envelope Probability if Inter-related with the Atmospheric Condition.

(See Figure E-3, Section D.)

D. Repeat Process to Identify All Cases Where Xc * Xa * Xe   10-9 E. Determine: “Flight Condition” (Xc * Xe)  Probable Flight Condition: 10-5  (Xc * Xe) < 0  Improbable Flight Condition: 10-9  (Xc * Xe) < 10-5 E-9

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AC 25-7D Appendix E Figure E-7. Probability Guidelines to Determine HQ Requirements

E.2.8 Table E-2 shows the minimum acceptable FAA handling qualities rating for a given flight condition, defined as a combination of the flight envelope conditions and the level of atmospheric disturbance, relative to the probability of the failure condition being evaluated. Table E-2 is not meant to imply that every atmospheric disturbance level and every flight envelope combination must be tested. It simply shows the minimum acceptable handling qualities rating for a handling qualities task conducted in a specific environmental state (i.e., atmospheric disturbance level), in a specific segment of the flight envelope, and in a specific system failure state.

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Appendix E Table E-2. Minimum HQ Requirements

Flight Condition Atmospheric Disturbance (Xa) (Xc*Xe) Light Moderate Severe Flight Envelope (Xe)

NFE OFE LFE NFE OFE LFE NFE OFE LFE Probable Condition

S S A A C C C C C Improbable Condition

A A C C C C NFE = Normal Flight Envelope OFE = Operational Flight Envelope LFE = Limit Flight Envelope S = Satisfactory A = Adequate C = Controllable E-11