Appendix 3
(h) Record any unusual engine operating conditions or maneuvers associated with the intended airplane mission profile.
(i) Test all maneuvers that will be approved for the airplane for aerobatic installations. All maneuvers should be tested to the left and right and, when applicable, at varying entry speeds. The testing may include, but is not limited to, the following maneuvers:
1 Chandelle.
2 Cuban 8 - Inside and outside.
3 Immelmann.
4 Knife Edge.
5 Loop.
6 Slow Roll.
7 Hammerhead.
8 Barrel Roll.
9 Tail Slide - Forward and aft pitch.
10 Hesitation Roll.
11 Upright Spin - Six turns with power off.
12 Vertical Roll.
13 Upright Spin - Six turns with maximum power after spin established.
14 Torque Roll.
15 Inverted Spin - Six turns with power off.
16 Snap Roll.
17 Inverted Spin - Six turns with maximum power after spin established.
18 Shoulder Roll.
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Appendix 3 19 Lomcevak.
20 Rolling 360° Turn.
21 Rudder Kicks with Full Deflection.
3. Test Conditions For Turbine Engine Installations.
a. General comments.
(1) The intended operating envelope and maneuver spectrum should be evaluated for each installation and test conditions added, deleted, or changed as necessary to fully evaluate propeller loads.
(2) Applicants may need to revise test conditions as data is reviewed during the test.
(3) Multi-engine installations may require testing on more than one engine, depending on airplane configuration and previous test experience.
(4) Testing may be required to verify repair allowances, such as reduced diameters, reduced thickness, and, for composite blades, significant shell repairs.
(5) Maximum power should be the first limit of torque or inter-turbine temperature.
(6) Flight testing should be conducted at the maximum airplane gross weight for certification and the minimum weight of the airplane in the test configuration.
(7) These test conditions are based on conventional turbine airplane engines with separate power and propeller controls that use a conventional constant speed propeller.
Installations that deviate from this standard will require modifications to the test conditions as appropriate to fully evaluate propeller vibration characteristics.
(8) Multi-engine airplanes should be tested in flight at high and low gross weights.
b. Test conditions. Tests under 3b(1) apply to all propellers; tests under 3b(2) apply only to propellers with four or more blades.
(1) Ground testing with the airplane static into the wind.
(a) Using power lever, increase propeller rpm from idle to maximum rpm in increments.
(b) Accelerate and decelerate between idle and maximum rpm.
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AC 20-66B CHG 1 Appendix 3
(c) Maintain maximum power and reduce rpm from maximum to minimum governing rpm in increments.
(d) Decrease blade angle to maximum reverse.
(2) Ground testing with the airplane static in a 45° cross tail wind of not less than 15 knots for propellers with four or more blades.
(a) Repeat 3b.(1)(a).
(b) Repeat 3b.(1)(b).
(c) Propeller feather/unfeather or engine start/shutdown as applicable.
(d) Record wind velocity at beginning and end of test.
(3) Flight testing at or below approximately 8000 ft. SL.
(a) Take- off rotation and initial climb with maximum power and rpm. Consider all possible flap positions. Test at high and low gross weights.
(b) Maintain maximum power and rpm and increase airspeed from minimum to VMO/VNE in increments. Test at high and low gross weights.
(c) Repeat b.(3)(b) with 70% torque.
(d) Maintain level flight and reduce torque from 100% to 40% in increments of approximately 10%.
(e) Record left and right banks at 30°, 45°, and 60° during climbing and level flight.
(f) Record incremental left and right rudder skids to the first limit of rudder travel or pedal force during climbing and level flight.
(g) Record stalls with flight idle power and approximately 60% torque.
(h) Record flight idle descent at incremental airspeeds. When investigating the actual vibration behavior of each propeller, the applicant should include the operating conditions that correspond to descent with the power levers at flight idle position and with airspeeds near the maximum operating limit speed (VMO) for airplanes equipped with turboprop engines.
(i) Select maximum and partial reverse at incremental speeds up to the maximum landing airspeed.
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AC 20-66B CHG 1 Appendix 3
(j) Record propeller feather/unfeather and/or engine shutdown/restart for multiengine installations, as applicable.
(k) Reduce power to idle for multi-engine installations on engine without instrumented propeller and record data with maximum power and rpm during single engine climb and level flight.
(4) Flight testing above approximately 12,000 ft SL. Consider higher altitudes for engines with significant thermodynamic capability.
(a) Maintain maximum power and maximum rpm and increase airspeed from minimum to VMO/VNE in increments. Test at high and low gross weights.
(b) Maintain maximum power and reduce from maximum rpm to minimum governing rpm in increments.
(c) Record flight idle descent at incremental airspeeds. When investigating the actual vibration behavior of each propeller, the applicant should include the operating conditions that correspond to descent with the power levers at flight idle position and with airspeeds near the maximum operating limit speed (VMO) for airplanes equipped with turboprop engines.
(5) Record any unusual engine operating conditions or maneuvers associated with the intended airplane mission profile.
(6) Test all maneuvers that will be approved for the airplane for aerobatic installations.
All maneuvers should be tested to the left and right and at varying entry speeds as applicable.
The testing may include, but is not limited to, the following maneuvers:
(a) Chandelle.
(b) Cuban 8 - Inside and outside.
(c) Immelmann.
(d) Knife Edge.
(e) Loop.
(f) Slow Roll.
(g) Hammerhead.
(h) Barrel Roll.
(i) Tail Slide - Forward and aft pitch.
(j) Hesitation Roll.
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Appendix 3
(k) Upright Spin - Six turns with power off.
(l) Vertical Roll.
(m) Upright Spin - Six turns with maximum power after spin established.
(n) Torque Roll.
(o) Inverted Spin - Six turns with power off.
(p) Snap Roll.
(q) Inverted Spin - Six turns with maximum power after spin established.
(r) Shoulder Roll.
(s) Lomcevak.
(t) Rolling 360° Turn.
(u) Rudder Kicks with Full Deflection.
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