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
PROBABILITY
RELATIONSHIPS
Figure 5 PROBABILITY GUIDELINES FOR
COMBINED OCCURRENCE FLIGHT CONDITIONS
HQR METHOD ELEMENT ISOLATED PROBABILITY
OF OCCURRENCE (at limit boundary) A. FLIGHT ENVELOPE Normal Generally associated with 10° NFE Flight practical, routine operation and/or Envelope: prescribed conditions, whether all-engine or engine inoperative.
Operational Generally associated with warning 10-3 OFE Flight onset; outside the normal flight Envelope: envelope.
Limit The most outside flight envelope, 10-5 LFE Flight generally associated with Envelope: airplane design limits or EFCS protection limits.
Refer to FIGURES 6 & 7.
Several of the flight parameter values may be necessary in combination in order to assign a given flight envelope. For the more influential flight parameters, such as AOA, speed, and NZ , the flight envelope may be determined by fewer or even one of the parameter values. Since the flight envelopes cover ranges of parameters (e.g.,Flaps UP: NZ LFE = 1.6 - 2.5), and are not just single point values, the above target probabilities for OFE and LFE might vary slightly depending on expected airplane behavior and assigned task within the range.
B. ATMOSPHERIC DISTURBANCE LEVEL LIGHT: Turbulence that momentarily causes 10° slight, erratic changes in altitude and/or attitude (pitch, roll, yaw).
Crosswinds up to 10 kts.
MODERATE:Turbulence that is similar to light 10-3 turbulence but of greater intensity.
Changes in altitude and/or attitude occur. Usually causes variations in indicated airspeed. Crosswinds up to 25 kts.
Figure 5 (CONT’D)
HOR METHOD ELEMENT ISOLATED PROBABILITY
OF OCCURRENCE (at limit boundary) SEVERE: Turbulence that causes large, abrupt 10-5 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.
C. FLIGHT CONTROL SYSTEM FAILURE STATE Normal Operation: 10º Probable Failures: 10º - 10-5 Improbable Failures: 10-5 - 10-9 D. COMBINATION GUIDELINES The above occurrence probability guidelines apply in isolation and should be modified when interrelationships exist according to the design or intended or expected operation of the airplane. For example, a severe windshear event may generate on Operational Flight Envelope or Limit Flight Envelope escape task at 10 º not 10-3 or 10-5 as shown above, in the limit since the operational procedure for escape would be to pull toward the AOA limit in windshear, perhaps experiencing overshoots of the steady value. Similarly, an airplane may experience overspeed, from VMO cruise, into the OFE due to a gust, in which the OFE task probability would be 10 º. not 10-3 in the limit. this probability adjustment concept would apply to EFCS failure cases where, for example, loss of warnings or exposure to reduced airplane stability might contribute to excursions outside the NFE or OFE, in which case the envelope probability might be appropriately increased.
The following steps can assist in the determination of combined occurrences required to determine the minimum applicable HQ Rating shown in FIGURE 12:
(1) Determine an occurrence probability value (se e FIGURES 9 & 10) considering the combination of factors for Flight Envelope ( Xe), Atmospheric Disturbance ( Xa), and EFCS failure state ( Xc) (after making necessary adjustments for interrelationships, as noted above).
(2) Ignore events whose occurr ences are less frequent than 10-9.
(3) For those combinational conditions occurring more frequently than 10-9. determine a "Flight Condition" value using only the combination values of EFCS Failure State ( Xc) and Flight Envelope ( Xe). Group this result ( Xc+Xe) into a category of either (Probable Flight Condition" (10 º - 10-5) or "Improbable Flight Condition" (10-5 - 10-9).
(4) Select or develop appropriate task(s) from FIGURE 11.
(5) Using this task(s), determine the minimum applicable HQ Rating s hown in FIGURE 12 with the given Flight Envelope and Atmospheric Disturbance, plus "Flight Condition" determined from step (3).
NFE OFE LFE NFE LFE OFE Normal Flight Envelope Operational Flight Envelope Limit Flight Envelope Rudder appropriate task/operation/or rudder lock eval VVVV VV V V V DFCMOS LOWEST SELECT FTO SW LIM STDY V LIM DYN CL MAX
1.3 OR OR OR MMM DFCMO LIM LIM OR
- 15 O +30 0 OR LIM +
- 67 0 OR NFE ENG INOP PITCH V AOA ROLL N Z
ALTITUDE PITCH V BUFFET N Z BETA * * * * LIM LIM LIM
1.3
1.6
2.5
0.8
0.0
- 1.0 IB DET +- 50 0 +- 40 0 +- 40 0 LIM DYN CL MAX SW LIM STDY OR OR Figure 6: Flaps UP Flight Envelopes