attack (e.g., a stick pusher), VCLMAX may not be less than the speed existing at the instant the device operates;
nZW = Load factor normal to the flight path at VCLMAX;
W = Airplane gross weight;
S = Aerodynamic reference wing area; and q = Dynamic pressure.
VCLMAX is determined with:”
25.103(a)(1) Change to read: “Engines idling, or, if that resultant thrust causes an appreciable decrease in stall speed, not more than zero thrust at the stall speed;”
25.103(a)(2) Change to read: “Propeller pitch controls (if applicable) in the takeoff position;”
25.103(a)(3) Insert a new paragraph that reads: “The airplane in other respects (such as flaps and landing gear) in the condition existing in the test or performance standard in which V SR is being used;”
25.103(a)(4) Renumbering of the old § 25.103(a)( 3) and change “V S” to “VSR.”
25.103(a)(5) Change to read: “The center of gravity position that results in the highest value of reference stall speed; and”
25.103(a)(6) Insert a new paragraph that reads: “The airplane trimmed for straight flight at a speed selected by the applicant, but not less than 1.13 VSR and not greater than 1.30 V SR.”
25.103(b) Change to read: “Starting from the stabilized trim condition, apply elevator control to decelerate the airplane so that the speed reduction does not exceed one knot per second.”
25.103(b)(1) Remove this paragraph.
25.103(b)(2) Remove this paragraph.
25.103(c) Insert a new paragraph that reads: “In addition to the requirements of paragraph (a) of this section, when a device that abruptly pushes the nose down at a selected angle of attack (e.g., a stick pusher) is installed, the reference stall speed, V SR, may not be less than 2 knots or 2 percent, whichever is greater, above the speed at which the device operates.”
25.107(b)(1) Change “1.2 VS” to “1.13 VSR.”
25.107(b)(2) Change “1.15 VS” to “1.08 VSR.”
25.107(c)(3) Insert a new paragraph that reads: “A speed that provides the maneuvering capability specified in § 25.143(g).”
25.107(g) Insert a new paragraph that reads: “V FTO, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by § 25.121(c), but may not be less than--
(1) 1.18 VSR; and
(2) A speed that provides the maneuvering capability specified in § 25.143(g).”
NOTE: Unless AOA protection system (stall warning and stall identification) production tolerances are acceptably small, so as to produce insignificant changes in performance determinations, the flight test settings for stall warning and stall identification should be set at the low AOA tolerance limit; high AOA tolerance limits should be used for characteristics evaluations.
25.111(a) Replace “a speed is reached at which compliance with §
25.121(c) is shown” with “V FTO is reached.”
25.119(b) Change to rea d: “A climb speed of not more than V REF.”
25.121(c) Change to read: “...for four engine airplanes, at V FTO and with – ”
25.121(d) Change to read: “In a configuration corresponding to the normal all-engines-operating procedure in which V SR for this configuration does not exceed 110 percent of the V SR for the related all-engines-operating landing configuration, the steady gradient of climb may not be less than 2.1 percent for twoengine airplanes, 2.4 percent for three-engine airplanes, and 2.7 percent for four-engine airplanes, with –”
25.121(d)(3) Change to read: “...but not more than 1.4 V SR; and”
25.121(d)(4) Add new paragraph as follows: “Landing gear retracted.”
25.125(a)(2) Change to read: “A stabilized approach, with a calibrated airspeed of not less than V REF, must be maintained down to the 50 foot height. VREF may not be less than ___
(i) 1.23 VSR0; and
(ii) VMCL established under § 25.149(f); and
(iii) A speed that provides the maneuvering capability specified in § 25.143(g).”
25.143(g) Insert a n ew paragraph that reads: “The maneuvering capabilities in a constant speed coordinated turn at forward center of gravity, as specified in the following table, must be free of stall warning or other characteristics that might interfere with normal maneuvering:
CONFIG-
URATION SPEED
MANEUVERING
BANK ANGLE IN A
COORDINATED TURN
THRUST/POWER
SETTING TAKEOFF V2 30° ASYMMETRICWAT-LIMITED.1 TAKEOFF V2 + XX 2 40° ALL-ENGINES-OPERATING CLIMB.3 ENROUTE VFTO 40° ASYMMETRICWAT-LIMITED.1 LANDING VREF 40° SYMMETRIC FOR-3° FLIGHT
PATH ANGLE
(1) A combination of weight, altitude and temperature (WAT) such that the thrust or power setting produces the minimum climb gradient specified in § 25.121 for the flight condition.
(2) Airspeed approved for all- engines-operating initial climb.
(3) That thrust or power setting which, in the event of failure of the critical engine and without any crew action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified for the takeoff condition at V 2, or any lesser thrust or power setting that is used for all-engines-operating initial climb procedures.”
25.145(a), (a)(1) Change to read: “It must be possible, at any point between the trim speed prescribed in § 25.103(a)(6) and stall identification (as defined in § 25.201(d)), to pitch the nose downward so that the acceleration to this selected trim speed is prompt with-
(1) The airplane trimmed at the speed prescribed in § 25.103(a)(6);”
25.145(b)(1) - (4) Change “1.4 VS1” to “1.3 VSR1.”
25.145(b)(1) Change “40 percent” to “30 percent.”
Change “stalling speed” to “reference stall speed.”
25.145(b)(6) Change “1.4 VS1” to “1.3 VSR1.”
Change “1.1 VS1” to “VSW.”
Change “1.7 VS1” to “1.6 VSR1.”
25.145(c) Change “1.1 VS1” to “1.08 VSR1.”
Change “1.2 VS1” to “1.13 VSR1.”
25.147(a), (a)(2), (c), (d) Change “1.4 VS1” to “1.3 VSR1.”
25.149(c) Change “1.2 VS” to “1.13 VSR.”
25.161(b), (c)(1), (c)(2), Change “1.4 VS1” to “1.3 VSR1.”
(c)(3), (d)
25.161(e)(3) Change “0.013 VS02” to “0.013VSR02.”
25.175(a)(2), (b)(1), (b)(2), Change “1.4 VS1” to “1.3 VSR1.”
(b)(3), (c)(4)
25.175(b)(2)(ii) Change “VMO + 1.4 VS1/2” to “(VMO + 1.3 VSR1)/2.”
25.175(c) Change speed range to: “...at speeds between V SW and 1.7 VSR1.”
25.175(d) Change speed range to: “...at speeds between V SW and 1.7 VSR0.”
25.175(d)(5) Change “1.4 VS0” to “1.3 VSR0.”
25.177(c) Change “1.2 VS1” to “1.13 VSR1.”
25.181(a), (b) Change “1.2 VS” to “1.13 VSR.”
25.201(a)(2) Change “1.6 VS1” to “1.5 VSR1” and “VS1” to “VSR1.”
Change “stalling speed” to “reference stall speed.”
25.207(c) Change to read: “When the speed is reduced at rates not exceeding one knot per second, in straight flight with engines idling and at the center-of-gravity position specified in § 25.103(a)(5), stall warning must begin, in each normal configuration, at a speed, V SW, exceeding the reference stall speed by not less than three knots or three percent, whichever is greater. Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which the stall warning began.”
25.207(d) Insert a new paragraph that reads: “In slow-down turns at 1.5g load factor normal to the flight path and airspeed deceleration rates greater than two knots per second, with the flaps and landing gear in any normal position, the stall warning margin must be sufficient to allow the pilot to prevent stalling (as defined in § 25.201(d)) when recovery is initiated not less than one second after the onset of stall warning.”
25.207(e) Insert a new paragraph that reads: “Stall warning must also be provided in each abnormal configuration of the high lift devices likely to be used in flight following system failures (including all configurations covered by Airplane Flight Manual procedures).”
25.233(a), and Change “0.2 VS0” to “0.2 VSR0.”
25.237(a), (b)(1) and (b)(2)
SUBPART D
25.735(f)(2) Change the KE equation to read: “KE = 0.0443(WV 2/N)” Change the V definition to read: “V = V REF/1.3” and “VREF = Airplane steady landing approach speed, in knots, at the maximum design landing weight and in the landing configuration at sea level; and”
25.735(g) Change to read: “The minimum speed rating of each main wheel-brake assembly (that is, the initial speed used in the dynamometer tests) may not be more than the V used in the determination of kinetic energy in accordance with paragraph (f) of this section, assuming...”
25.773(b)(1)(i) Change “1.6 VS1” to “1.5 VSR1.”
SUBPART E
25.1001(c)(1) and (c)(3) Change 1.4 VS1 to 1.3 VSR1.
SUBPART F
25.1323(c)(1) Change “1.3 VS1” to “1.23 VSR1.”
25.1323(c)(2) Change “1.3VS0” to “1.23VSR0.”
25.1325(e) Change “1.3 VS0” to “1.23 VSR0.”
Change “1.8 VS1” to “1.7 VSR1.”
Part 36 (Noise Standa rds:
Aircraft Type and Airworthiness Certification) NOTE: It has been determined that the following is equivalent for the purposes of FAR Part 36 certification.
Appendix C, Sec. C36.9(e)(1) Change “1.30VS + 10 knots” to “VREF + 10 knots.”
FCAA POSITION:
APPLICANT POSITION:
CONCLUSION:
________________________________ _________________________ Transport Airplane Directorate Date
Aircraft Certification Service
APPENDIX 6
SAMPLE FLIGHT TEST PROGRAM [RESERVED]
APPENDIX 7 - FAA HANDLING QUALITIES RATING METHOD
a. Explanation. With the advent of transport category airplanes employing electronic flight control systems (EFCS) that provide control augmentation, and sometimes employ limiting systems, the ability to make a literal finding of compliance with many of the stability and control requirements of Part 25 was eroded. As a result the Handling Qualities Rating Method (HQRM) presented in this appendix was developed to provide a pseudo-quantitative means of evaluating airplane flying qualities. The HQRM draws on a matrix of parameters in defining the desired handling characteristics, including atmospheric conditions, flight envelope conditions, pilot task tracking requirements, and probability of occurrence.
(1) Figure 1 presents a list of deficiencies that exist for applying existing regulations to airplanes with maneuver demand electronic flight control systems.
(2) Since the subject airplanes have redundant EFCS capabilities, which generally provide reduced levels of control duplication with progressive failure states, a "failure consequence vs. probability" type of approach is applicable (see Figure 2).
b. Procedures. The HQRM is to be applied as a task-oriented system to be used in the evaluation of airplane handling qualities in accordance with the following procedures.
(1) A probability of occurrence versus effect philosophy is applied in relating the flight test variables to flight envelope characteristics, atmospheric disturbance levels, and probability of a specific flight control failure state. The combined application of these parameters to make a finding of compliance is shown schematically in Figure 4.
(2) It has also become necessary to create a defined set of criteria by which to evaluate the handling qualities of EFCS-equipped airplanes. In an attempt to create a system that can be used in a standardized manner, the handling qualities rating method has been limited to three levels: Satisfactory (SAT), Adequate (ADQ), and Controllable (CON). These pilot ratings are defined and compared with other established rating scales in Figure 5A. Handling qualities must be demonstrated to meet one of these ratings levels for a particular flight condition that will be defined in terms probability of occurrence, flight envelope, and level of atmospheric disturbance (see Figures 5B, C, and D).
(3) Matrices can be formed of measurable flight parameters for the normal, operational, and limit flight envelopes. These are shown in the "spider web" charts for flaps up and flaps down in Figures 6 and 7, respectively.
(4) A description of the pilot ratings (SAT, ADQ, & CON) is presented in Figure 8 along with their equivalent Cooper-Harper and Military Standard ratings for comparison.
(5) Figure 9 presents the method for combining the various flight condition parameter probabilities that will, in turn, be used to determine the minimum handling qualities rating. This method is shown in a graphical format in Figure 10.
(6) The HQRM is to be used in a task-oriented environment to evaluate airplane handling qualities while performing typical static and dynamic maneuvers. A sample list of such tasks is presented in Figure 11.
(7) Figure 12 shows a table of the minimum 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.
CURRENT BASIC OBJECTIVE LIKELY DEFICIENCY FOR
REGULATION AIRPLANE WITH FBW
MANEUVER DEMAND EFCS
25.171/173/175 Static Long. Stab: Literal noncompliance: Airplane 1 lb/6 kts, average has short-term path stability.
25.171/177 Stat. Lat-Dir Stab: Literal noncompliance for roll- Fa/Beta > 0 rate command EFCS, when airplane in steady sideslip.
25.671(c)(2) Control Systems, General: Proper objective, but no Continued safe flight and structured approach showing landing after combination compliance for matrix of EFCS of failures not shown to failure modes and flight be extremely improbable. conditions.
25.672(c)(1)-(3) Various HQ requirements • Deals only with single failures for failure of stability (e.g., Yaw Damper-only augmentation/power- technology) operated systems. • Presumes controllability and maneuverability requirements can be maintained, yet trim, stability, and stall characteristics can be impaired.
25.1309(b)(1) Occurrence of any failure • Applies to systems, but has condition which would indirect relation to flight prevent continued safe characteristics evaluationflight and landing is clarification needed.
extremely improbable • Differences between U.S. and European airworthiness interpretations.
Figure 1: Airworthiness HQ Regulations Impacted/Outpaced by Technology.
Catastrophic Accident Adverse UNACCEPTABLE Effects on Occupants Airplane Damage Consequences of Consequences of Failure Condition Failure Condition Emergency Procedures Abnormal Procedures ACCEPTABLE Nuisance Normal Probable Improbable Extremely Improbable *From AC 25.1309-1A Probability of Failure Condition Probability of Failure Condition (Sys. Design & Anal.)
Figure 2: Probability vs. Consequence Graph*
Certification Program Need:
A320 1988/89 MD-11 1989/90 B777 1995/96 Informal Contacts NASA Dryden AFFTC AFWAL Society/Industry Documents Cooper-Harper Rating Method Existing FAA Contract Research
MIL SPEC/STD Rating Methods & Elements
FAA HANDLING QUALITIES RATING METHOD (Current Special Conditions, Issue Papers, & Certification Review Items Figure 3: Development of FAA HQRM Criteria ADAPTED HQ REG’S AND ADVISORY MATERIAL
OBJECTIVES AND APPLICABILITY
FAILURE
CONDITIONS FLIGHT
ENVELOPES
ATMOSPHERIC
DISTURBANCE
COMBINATION
METHODOLOGY TASKS
HQ RATING
CATEGORIES
FIND COMPLIANCE Figure 4: Major Elements of Task Oriented Handling Qualities Rating Method