Appendix E E-2 Figure E-1. Overall HQRM Process
HANDLING QUALITIES REQUIREMENTS
OBJECTIVES AND APPLICABILITY Xa
ATMOSPHERIC
DISTURBANCE Xc
FAILURE
CONDITIONS Xe FLIGHT
ENVELOPES Xc * Xa * Xe
COMBINATION
METHODOLOGY
PILOT TASKS
HQ RATING
CATEGORIES
FIND COMPLIANCE
PROBABILITY
RELATIONSHIPS
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- Harper Rating Military Standard HQ Rating Definition 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
Appendix E E-3 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.
Appendix E E-4 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.
Appendix E E-5 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.
Appendix E E-6 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) Normal Operation:
100 Probable Failures:
100 - 10-5 Improbable Failures:
10-5 - 10-9 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.
Appendix E E-7 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 Normal Flight Envelope Operational Flight Envelope Limit Flight Envelope NFE LFE OFE V
DET
* or or -150
* *
0.8
0.0
- 1.0 or IB V ENG INOP
or
or
1.6
1.3 LIM LIM
LIM DYN
LIM
LIM DYN
2.5 LIM
LIM
or
V
MMO
ALTITUDE AOA ROLL BETA BUFFET V PITCH V PITCH a a a VMO MFC VFC a sw CLMAX
CLMAX LIM STDY LIM STDY VSW j or ±670 ±500 ±400 VFTO ±400 V
1.3VS LOWEST SELECT NFE NFE OFE LFE +300 MD VD NZ NZ LIM or *Rudder appropriate to task/operation/ or rudder lock evaluation
Appendix E E-8 Figure E-5. Flaps DOWN Flight Envelopes V
DET or or -150 * *
0.8
0.5
0.0 or IB
ENG INOPor or
1.6
1.3
LIMDYN LIM LIM DYN
2.0 LIM LIM or V
ALTITUDE AOA ROLL BETA BUFFET V PITCH V PITCH a a a VFE VFE + V a sw CLMAX
CLMAX LIM STDY LIM STDY VSW j or ±670 ±500 ±400 V2+X X ±400 LAND NFE NFE OFE LFE +300 NZ NZ Normal Flight Envelope Operational Flight Envelope Limit Flight Envelope NFE LFE OFE LIM VFE + V TO & L +3000 TO & L +3000 ±300
TAKEOFF VREF * * V *Rudder appropriate to task/operation/ or rudder lock evaluation 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.
Appendix E E-9 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
Appendix E E-10 Figure E-7. Probability Guidelines to Determine HQ Requirements 0 -1 -2 -3 -4 -5 -6 -7 -8 -9
PROBABLE FAIL IMPROBABLE FAIL EFCS FAILURE RATE -10Xc Xc= -9 -8 -7 -6 -5 -4 -3 -2 -1 0 EFCS *Based on (Xe+Xc) Xe Xc Xa IMPROB FLT CONDPROB FLT COND* PROBABILITY -10x
FLIGHT ENVELOPE &
ATMOSPHERIC DISTURBANCE **Gust intensity variations may be expected with altitude and between u, v, w axes
OFE LFENFE
MOD SEVERELIGHT 3 5 8 14 20GUST** fps SHEAR XWIND 10 18 25 33 45 kts
SMALL RAMP INCR & JFK DEN MSY DFW (TO&L) ug FLIGHT
ENVELOPE
ATMOSPHERIC
DISTURBANCE
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.
Appendix E E-11 Table E-2. Minimum HQ Requirements Flight Condition (Xc*Xe) Atmospheric Disturbance (Xa) 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
Appendix F F-1 APPENDIX F. CORRECTION OF AIR MINIMUM CONTROL SPEED TO
STANDARD CONDITIONS F.1 Overview.
The following analysis presents three methods of correcting a flight test derived value of air minimum control speed to standard conditions. These methods are applicable only to rudder deflection limited VMCA, for either jet or propeller driven airplanes. The effect of banking into the operating engine is accounted for, and the method will work with either fixed pitch or constant speed propellers, including the effects of windmilling drag. For rudder pedal force limited VMCA, see appendix G of this AC.
F.2 Theoretical Basis.
Given the static lateral/directional equations of motion for straight line, unaccelerated flight:
∑ 𝐹𝑦 = 0 𝐶𝑦𝛽 ⋅ 𝛽 + 𝐶𝑦𝛿𝑎 ⋅ 𝛿𝑎 + 𝐶𝑦𝛿𝑟 ⋅ 𝛿𝑟 = 𝐶𝐿 𝑠𝑖𝑛 ∅ (1) ∑ 𝑀𝑥 = 0 𝐶𝑙𝛽 ⋅ 𝛽 + 𝐶𝑙𝛿𝑎 ⋅ 𝛿𝑎 + 𝐶𝑙𝛿𝑟 ⋅ 𝛿𝑟 = 0 (2) ∑ 𝑀𝑧 = 0 𝐶𝑛𝛽 ⋅ 𝛽 + 𝐶𝑛𝛿𝑎 ⋅ 𝛿𝑎 + 𝐶𝑛𝛿𝑟 ⋅ 𝛿𝑟 = 𝐶𝑛𝑎 (3) Where:
𝐶𝐿 = 295 ⋅ 𝑊𝑉𝑒2 ∙ 𝑆 𝐶𝑛𝑎 = 295 ⋅ 𝐹𝑛𝑎 ⋅ 𝑙𝑒𝑉𝑒2 ⋅ 𝑆 ⋅ 𝑏 W = Weight (lbs) Ve = Equivalent airspeed (kts) S = Wing area (ft2) Fna = Asymmetric net thrust (lbs) Fna = (Fn + Dw) for engine inoperative Fna = (Fn + Fi) for engine at idle Fn = Net thrust of the operating engine (lbs) Fi = Idle engine net thrust (lbs) Dw = Windmill drag (lbs) le = Distance from aircraft center line to engine thrust line (ft) b = Wingspan (ft)
Appendix F F-2 F.3 Constant Cn Method.
F.3.1 For the case where full rudder deflection is achieved, r is a constant, and the system of equations can be resolved to an identity that shows that Cna is a linear function of CL sin Ø.
𝐶𝑛𝑎 = 𝐴 ⋅ 𝐶𝐿 𝑠𝑖𝑛 ∅ + 𝐵 (4) F.3.2 If it is assumed that test and standard day VMCA occur at the same angle-of-attack and bank angle, the asymmetric yawing moment coefficient will be constant, and VMCA can be corrected to standard conditions by the relationship:
𝑉𝑀𝐶𝐴𝑠 = 𝑉𝑀𝐶𝐴𝑡 ⋅ √ 𝐹𝑛𝑎𝑠 𝐹𝑛𝑎𝑡 for turbojets 𝑉𝑀𝐶𝐴𝑠 = 𝑉𝑀𝐶𝐴𝑡 ⋅ [ 𝑇𝐻𝑃𝑠√𝜎𝑠 𝑇𝐻𝑃𝑡√𝜎𝑡 ] 1 3 ⋅ √ 𝐹𝑛𝑎𝑠 𝐹𝑛𝑎𝑡 for propeller driven Where:
THPs = Maximum AFM scheduled brake/shaft horsepower multiplied by standard day propeller efficiency.
THPt = Test day brake/shaft horsepower where VMCA was achieved multiplied by test day propeller efficiency.
√𝜎𝑠 = Atmospheric density ratio at standard conditions.
√𝜎𝑡 = Atmospheric density ratio at test conditions.
F.3.3 Windmilling shaft horsepower is not considered because the current part 25 takeoff requirements for propeller driven airplanes result in such large performance penalties with a windmilling propeller that all part 25 turboprops to date have had autofeather installed.
F.3.4 Since both net thrust and shaft horsepower vary with speed, use of these equations will require an iterative solution. Because this constant Cn method does not consider the effect on VMCA due to variations in bank angle, weight, sideslip angle, or adverse yaw, its use is limited to corrections of 5 percent or less in asymmetric net thrust or power.
F.3.5 For corrections beyond 5 percent, the relationship shown in equation (4) should be used, and enough flight test data should be obtained to define the correlation between Cna and CL sin Ø.
F.4 Graphical Method.
F.4.1 In theory this data could be obtained by varying any combination of asymmetric power or thrust, airspeed, weight, and bank angle that would provide a representative variable set. However, since VMCA and stall speed are nearly coincident for most airplanes, there are some severe constraints on most of the variables. Typically, any reduction in