Appendix 6 A6-8
Figure 7. Flaps DOWN Flight Envelopes
Appendix 6 A6-9
Figure 8. Pilot Ratings
FAA COMPARISON HQ FAA DEFINITION CH* MIL STANDARD
RATING LEVEL QUAL
Satisfactory
Full performance criteria met with routine pilot effort and attention
1-3.5
SAT
Adequate
Adequate for continued safe flight and landing:
full or specified reduced performance met, but with heightened pilot effort and attention.
3.5-6.5
ACCEPT
Controllable
Inadequate for continued safe flight and landing, but controllable for return to safe flight condition, a safe flight envelope, and/or reconfiguration so that HQ are at least ADEQUATE.
6.5-8.0
CON
NOTE: *Cooper-Harper Rating
Appendix 6 A6-10 Figure 9. Probability Combination Leading to HQ Rating
Analyze Failures/Determine EFCS Operating State (Xc) Probability
-- Predicted failure rates/check failure co-dependence
-- Equipment Inoperative Dispatch under MEL
-- Service Difficulty Records (continuing airworthiness)
Assume Envelope Probabilities (Xe) and Atmospheric Probabilities (Xa) for Scenario
Modify the Envelope Probability (to Xem) if Co-dependent with Atmospheric Condition (See figure 5, Section D.) If not Co-dependent, Xem = Xe
Continue with Cases Xc + Xa + Xem 10 -9
Develop: “Flight Condition” (Xc + Xem)
-- PROBABLE FLIGHT CONDITION: -5 (Xc + Xem) < 0
-- IMPROBABLE FLIGHT CONDITION: -9 (Xc + Xem) < -5
Develop Tasks/Ensure HQ Requirements Met
(Xc) (Xa) (Xe) (S-SAT,A-ADQ,C-CON) FLIGHT CONDITION + ATMOSPHERIC + ENVELOPE REQUIREMENTS FOR FAA
R A T I N G
-- Flight Test
-- Simulator (high risk and specific atmospheric conditions)
Appendix 6 Figure 10. Probability Guidelines to Determine HQ Requirements EFCS FAILURE RATE - 10Xc
PROBABLE FAIL IMPROBABLE FAIL T -1 -2 -4 -5 -7 -8 -9 IMPROB FLT COND *Based on -8 (Xe+Xc) EFCS PROBABILITY -10x PROB FLT COND* Xe Xc FLIGHT ENVELOPE &
ATMOSPHERIC DISTURBANCE -2 **Gust intensity variations may be expected with altitude and between u, v, waxes
NFE OFE LFE ENVELOPE FLIGHT
LIGHT MOD SEVERE ATMOSPHERIC
DISTURBANCE oug GUST** 14 20 fps
SMALL RAMP INCR & JFK DEN MSY DFW (TO&L) SHEAR 10 18 25 33 45 kts XWIND A6-11
Appendix 6 A6-12 Figure 11. General HQ Task Categories
A. TRIM & UNATTENDED OPERATION Characteristics of the airplane to stay at or depart from an initial trim or unaccelerated condition.
Dynamic and flight-path response to pulse (3 axes) Dynamic and flight-path response to atmospheric disturbance Spiral stability (e.g., release 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, but not reflecting the normal, daily commercial use of the airplane. Maneuvers may be initiated outside the NORMAL FLIGHT ENVELOPE and transition flight envelopes. Most of these maneuvers are representative of engineering airworthiness stability and control tests.
Pitch/ -- Wind-up turn or symmetric pull-up/push-over Longitudinal -- 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 -- Go around/power application from low speed -- Arrest of high sink rate, at touchdown or level-off altitude -- Collision avoidance roll/pull -- Takeoff and landing flare with abuse or high crosswind
C. CLOSED-LOOP PRECISION REGULATION OF FLIGHT PATH Generally, these are tightly-bounded, pilot closed-loop tasks performed in routine commercial flight. These controlling tasks are almost exclusively associated with the NORMAL FLIGHT ENVELOPE, or certainly not far outside the NFE boundary.
ILS and precision touchdown, various atmospheric disturbance and initial offset Formation flying (as simulator for maneuver tracking)
Appendix 6 A6-13
SPD/ALT/HDG tracking, in various atmospheric disturbance and cockpit display status, for:
- - T a k e o f f
- - C l i m b
- - C r u i s e
- - D e s c e n t
- - H o l d -- Configuration changes/power changes -- Transition between aforementioned
Figure 12. Minimum HQ Requirements
ATMOSPHERIC DISTURBANCE (Xa)
FLIGHT LIGHT MODERATE SEVERE CONDITION FLIGHT ENVELOPE (Xe) (Xc+Xem) 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
S=SATISFACTORY A=ADEQUATE C=CONTROLLABLE
Appendix 7 A7-1
Appendix 7
Rudder Pedal Force-Limited Air Minimum Control Speed
The following analysis presents one method of addressing rudder pedal force limited air minimum control speed. This method is applicable to 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 deflection limited VMCA, see Appendix 3.
Given the static lateral/directional equations of motion for straight line, unaccelerated flight:
Fy = 0 Cy + C yaa + Cyrr = CL · sin
Mx 0 Cl + Claa Cl r r = 0
Mz = 0 Cn + Cnaa Cnrr = Cna
For a reversible control system, rudder force versus deflection is:
F R = GR · q · SR · cR · Ch R · R
and R = kR · FV Re 2
Substituting for R in equations (1) through (3), and solving, results in an identity of the form:
F R = A·Fna - B·Wsin
All the airspeed terms cancel, indicating that the engine-out rudder force required for straight flight is not a function of airspeed, but only of asymmetric thrust, weight, and bank angle. If asymmetric thrust did not vary with airspeed, it would be possible to stabilize at any airspeed with the same rudder force. At higher speeds, less rudder deflection would be required (varies inversely with Ve2), but the same force would be required (varies directly with Ve2). When a force limited VMCA is determined during flight test, the variation in rudder force with airspeed results solely from the change in net thrust with speed, and if an airspeed (thrust) is reached at which the rudder force is 150 lbs, there is no way to correct this force limited VMCA to any other thrust level. Therefore, if VMCA is rudder pedal force limited, takeoff thrust at all flight conditions should be limited to the test value of asymmetric thrust.
Appendix 7 A7-2
In some cases, it is possible to achieve full rudder deflection at the test altitude without reaching a pedal force limit, but with the higher thrust at standard conditions, a force limit would exist.
To preclude missing this crossover effect, the following analysis should be performed whenever test day rudder pedal forces are greater than 90 percent of the CFR limit (i.e., 135 lbs after amendment 25-42; 162 lbs prior to amendment 25-42).
1. At any convenient airspeed (typically 1.13 VSR with minimum takeoff flaps), shut down the critical engine, and leave it windmilling (propeller feathered if autofeather is required), apply maximum available power/thrust to the operating engine, and while maintaining constant heading, vary the bank angle from 10° to less than 5° in approximately 2°-3° increments, noting the rudder force at each stabilized bank angle.
2. Plot the rudder force vs Wsin for each of the test points.
3. Calculate Wssin 5°, where Ws is either the average test weight, or the lightest weight scheduled in the AFM, and define standard day rudder force (FRs) as the intersection of this value of Wsin and the curve from step (2). For example:
Fnat = 2600 lbs V = 1.13 V SR W s = 9000 lbs FR=166 lbs Wsin = 784 lbs -50 0 50 100 150 200 250 400 800 1200 1600 Wsinlbs Rudder Pedal Force (FR) - lbs
Appendix 7 A7-3
4. Determine the maximum allowable asymmetric thrust from the relationship:
FFna namax t 150FRs * *( 180FRs prior to amendment 25-42)
Assuming a 180 lb force limit: 1661802600F maxna 2820 lbs
5. Plot maximum scheduled AFM thrust vs airspeed, and determine V MCA at the intersection of this curve and Fnamax :
80.5 KEAS 2820 lbs 2600 2650 2700 2750 2800 2850 2900 2950 3000 60 80 100 120 140 160 Ve - kts.
Fna - lbs.
If the force limited VMCA value is high enough to impact adversely the takeoff speed schedule, it can be reduced to an acceptable value by derating takeoff thrust. For example, if the standard day rudder force (FRs) was 140 lbs on an amendment 25-42 airplane, the maximum allowable asymmetric takeoff thrust would be:
F 2600 150140namax 2686 lbs
Using the same maximum asymmetric thrust available vs airspeed as before:
Appendix 7 A7-4 172 KEAS 2686 lbs 2600 2650 2700 2750 2800 2850 2900 2950 3000 60 80 100 120 140 160 180 200 Ve - kts.
Fna - lbs.
Because of the shallow thrust lapse rate with airspeed, the force limited VMCA for these conditions would be 172 knots, which is obviously unacceptable. To reduce this value back to 80 knots (or any other speed), takeoff thrust should be derated to a level which provides a maximum asymmetric thrust value of Fnamax at the desired VMCA (80 knots in this example). The amount of derate required can be determined from the following plot:
Maximum Thrust Derated Thrust (5%) 80 KEAS 2686 lbs 2400 2500 2600 2700 2800 2900 3000 50 100 150 200 Ve - kts Fna - lbs
For a given weight and bank angle, rudder pedal force is determined solely by asymmetric thrust;
consequently, takeoff thrust should be limited to a value which results in a pedal force no greater than 150 lbs (180 lbs prior to amendment 25-42).