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
NFE OFE LFE NFE LFE OFE Normal Flight Envelope Operational Flight Envelope Limit Flight Envelope Rudder appropriate to task/operation/or rudder lock eval V V V SW LIM STDY V LIM DYN CL MAX OR OR 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
1.3
1.6
0.8 IB DET +- 50 0 +- 40 0 LIM DYN CL MAX SW LIM STDY OR OR Figure 7: Flaps DOWN Flight Envelopes +- 30 0 TO +- 40 0 LAND
2.0
0.5
0.0 TO & L +3000 TO & L +3000 V FE V FE + V FE + V REF V 2 V 2 + XX
FIGURE 8: Pilot Ratings FAA HQ RATING
FAA DEFINITION
COMPARISON
MIL STANDARD
LEVEL QUAL CH SAT ADQ CON Full performance criteria met with routine pilot effort and attention.
1-3.5
3.5-6.5
6.5-8.0 SAT ACCEPT CON Adequate for continued safe flight and landing; full or specified reduced performance met, but with 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.
1 2 3 heightened pilot effort and attention.
* Note: * Cooper-Harper 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 airworthines) · Assume Envelope Probabilities ( Xe) and Atmospheric Probabilities ( Xa) for Scenario · Modify the Envelope Prob ability (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
DISTURBANCE FAA RATING
- Flight Test
- Simulator (high risk and specific atmospheric conditions) FIGURE 9. PROBABILITY COMBINATION LEADING TO HQ RATING
FIGURE 10 : Probability Guidelines to determine HQ Requirements
NFE OFE LFE
MOD SEVERE FLIGHT
ENVELOPE
ATMOSPHERIC
DISTURBANCE 3 5 8 14 20 fps 10 18 25 33 45 kts SHEAR XWIND
SMALL RAMP INCR & JFK DEN MSY DFW (TO & L) LIGHT GUST**ug Xc 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 0 -1 -2 -3 -4 -5 -6 -7 -8 -9
PROBABLE FAIL IMPROBABLE FAIL Xc = EFCS FAILURE RATE ~10 EFCS
FLIGHT ENVELOPE &
ATMOSPHERIC DISTURBANCE with altitude and between u, v, w axes Xe Xc Xa *Based on (Xe+Xc) **Gust intensity variations may be expected PROB ABILI TY ~10 X IM PR O B FL T C O PR O B FL T C O N
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/ o Wind-up turn or symmetric pull-up/push-over Longitudinal o Slow-down-turn at fixed g or on AOA or g-limiter o Stall or AOA-limiter approach o Push/pull off trim speed * Roll o Rapid bank-to-bank roll * Yaw o Sudden heading change o Constant heading sideslip * Operational o Pitch/roll upset recover o Emergency descent o Climbing/diving turn o Takeoff/land windshear escape maneuver o Go around/power application from low speed o Arrest of high sink rate, at touchdown or level-off altitude o Collision avoidance roll/pull o 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) * SPD/ALT/HDG tracking, in various atmospheric disturbance and cockpit display status, for: o Takeoff o Climb o Cruise o Descent o Hold o Configuration changes/power changes o Transition between aforementioned Figure 11: General HQ Task Categories
(Xe) (Xa)
FIGURE 12: Minimum HQ Requirements
ATMOSPHERIC DISTURBANCE
LIGHT MODERATE SEVERE
FLIGHT ENVELOPE
PROBABLE
CONDITION
IMPROBABLE
CONDITION FLIGHT
CONDITION
NFE OFE LFE NFE OFE LFE NFE OFE LFE S A C S A
A A C C C C C C C C S = SATISFACTORY A = ADEQUATE C = CONTROLLABLE (Xc + Xem)
APPENDIX 8 FUNCTIONAL AND RELIABILITY TESTS -§ 21.35(b)(2)
1. Explanation.
a. In order to satisfactorily accomplish the objectives concerning additional flight tests and the extent thereof, the Administrator deems it necessary that:
(1) A comprehensive and systematic check be made, in flight, of the operation of all components to determine whether they "function properly" (i.e., perform their intended function without introducing safety hazards).
(2) Sufficient FAA test experience, and supplementary experience gained from operators' route proving tests, should be obtained and evaluated to give reasonable assurance that the airplane is "reliable" (i.e., should continue to function properly in service).
NOTE: In order to obtain wider experience, manufacturers are encouraged to cooperate with airlines or other responsible operators in operating airplanes with provisional type certificates under service conditions.
(3) Appropriate corrective action be taken when the need therefor is determined under subparagraphs (1) and (2) of this paragraph.
2. Procedures . The principal FAA flight test pilot for the project will act as coordinator of all flight activities during the official program, and that pilot (or a designated alternate) will participate in all flights. Other FAA personnel will not board the functional and reliability (F & R) airplane(s) during these activities, particularly in regard to flight plans and procedures, unless authorized by the flight test pilot. The manufacturer's pilot should be in command of all flights, but FAA pilots will fly the airplane to determine compliance with § 21.35(b)(2). Other FAA personnel (e.g., representatives of other divisions and specialists) will participate in the flight tests, when deemed necessary, to accomplish the purpose of the tests.
a. Test Time. It is highly desirable that function and reliability test programs be administered uniformly so that the program and flight time for a given project would be approximately the same, regardless of which FAA Aircraft Certification Office (ACO) administered the project. This is difficult to achieve without establishing fixed arbitrary test times, which would obviously be contrary to the intent of § 21.35 (b)(2). The following procedure, which permits considerable flexibility, is therefore established as guidance for administering F & R test programs:
(1) For a turbine engine-powered airplane incorporating engines of a type not previously certifi cated, §
21.35(f)(1) requires an F & R test program of at least 300 hours. This 300 hour minimum may also be applied to a complex new airplane model (e.g., an airplane with an electronic flight control system (fly by wire)). Though some F & R test requirements can be completed concurrently with certification testing (if relevant design conformity can be shown), experience has indicated the desirability of obtaining at least 150 hours on a production configured airplane. For a previously certificated airplane, the F & R program requirement should be commensurate with the modifications or changes.
(2) When supplementary experience is not taken into account, and the airplane is conventional with regard to complexity and design features and does not incorporate engines that have not been previously certificated (including derivative engines), it has been found that function and reliability tests can be performed within 300 hours. This time may be reduced if credit is granted for certain types of component testing (see paragraph 2e(2)) and for supplementary experience (see paragraph 2a(3)(iii). However, it may be necessary to increase the 150-hour minimum F & R test requirement of § 21.35(f)(2) if difficulties are encountered or for unusual cases of complexity.
(3) When satisfactory supplementary experience is available and taken into account the following allowances should be used as a guide and applied with judgment in reducing the official flight test time. However, in any case, the official F & R test program should provide sufficient time to accomplish the objective of paragraph 1a(2) in accordance with the procedures described in paragraphs 2e(3) and (4).
(i) For Intensive Experience . When the allowance is based on the total time of any one airplane in airline crew training and similar intensive operations, two hours of such operation may be considered equivalent to one hour of official testing.
(ii) For Miscellaneous Experience . When the allowance is based on the total time of any one airplane, five hours of such experience may be considered equivalent to one hour of official testing.
(iii) Reduction for Supplementary Experience . Whenever a reduction of official test time is desired on the basis of supplementary experience, such experience should be adequately recorded and submitted to the responsible FAA aircraft certification office as described in paragraph 2f(2).
b. Test Airplane . To facilitate completion of the type certification procedure, one airplane, in production configuration or equivalent, should be used for the official functional and reliability tests while another airplane (or airplanes) is used for the routine-type tests. In this case, the test time on at least one airplane would be sufficient to accomplish the objective of paragraph 1a(2).
c. Modified Types . The procedure outlined in paragraph d., below, applies to new type designs. When a design employs components (parts) identical to those used in previous designs, credit may be given for the supplementary experience available for such components. When a design is modified (e.g., several versions of the same basic type with different engines, propellers, etc.), the modified features and components should be rechecked in accordance with paragraph 2e(6), below.
d. Test Program. The project engineers of the responsible FAA ACO will propose guidelines for developing an F & R test program at the preflight Type Board meeting (prior to commencement of FAA certification flight tests) and coordinate this with the airplane manufacturer. Near the conclusion of the type certification tests, the FAA certification engineers will again meet with the manufacturer to review the experience gained in those tests, review changes made in the design, consider any additional supplementary experience, and revise the proposed F & R test program accordingly. In application, there is generally considerable overlap of the certification and F & R test programs, thus making a definite transition point indiscernible.
e. Planning and Execution of Test Program . The following points should be considered:
(1) The test program should be sufficiently well planned to enable its execution in an efficient manner without overlooking important items. Documentation should focus on the test objective(s) but does not necessarily require the type of detail maintained for type certification testing. The FAA project engineers will review the design features and equipment (appliances) with respect to the general objective and prepare a list showing:
(i) Components and systems to be checked in accordance with the procedures described in paragraph 2e(4).
(ii) A brief description of the operations to be performed, where these are not obvious (referencing any necessary operating instructions).
(iii) Special checks or likely critical conditions.
(iv) Estimated flight time required.
(2) Allowance may be made for those functional tests whose requirements are covered by 14 CFR part 25 type certification tests. Allowance may also be made for qualification-type testing of new features and equipment; however, the flight test program should be planned to determine the adequacy of these tests and the accuracy of the simulated operating environment (e.g., to determine whether the actual environmental conditions such as temperature variation, etc., are covered by the test simulations) when these may be critical, and to determine whether the installation and connected systems are satisfactory. This does not imply that flight tests must be conducted under the most severe outside air temperatures likely to be encountered in service. It should normally be possible to determine the effects of extreme outside temperatures on local temperatures by extrapolation or by