Section 10. FIRE PROTECTION [RESERVED] Section 11. MISCELLANEOUS [RESERVED] CHAPTER 5. POWERPLANT Section 1. GENERAL
89. FAR 25.901 Installation [RESERVED]387
90. FAR 25.903 Engines387
FAR 25.903(b) Engine Isolation387
FAR 25.903(c) Control of Engine Rotation387
FAR 25.903(d) Turbine Engine Installations388
FAR 25.903(e) Engine Restart Capability389
91. FAR 25.904 Automatic Takeoff Thrust Control Systems (ATTCS)390
92. FAR 25.905 Propellers392
93. FAR 25.907 Propeller Vibration [RESERVED]392
94. FAR 25.925 Propeller Clearance [RESERVED]392
95. FAR 25.929 Propeller Deicing392
96. FAR 25.933 Reversing Systems393
97. FAR 25.934 Turbojet Engine Thrust Reverser Sys. Tests [RESERVED]396
98. FAR 25.937 Turbopropeller-Drag Limiting Systems396
99. FAR 25.939 Turbine Engine Operating Characteristics398
100. FAR 25.941 Inlet, Engine, and Exhaust Capability (RESERVED398
101. FAR 25.943 Negative Acceleration399
102. FAR 25.945 Thrust or Power Augmentation System [RESERVE D]399
Section 2. FUEL SYSTEM
[103-108] [RESERVED]419
109. FAR 25.959 Unusable Fuel Supply419
110. FAR 25.961 Fuel System Hot Weather Operation421
[111-116] [RESERVED]423
117. FAR 25.975 Fuel Tank Vents and Carburetor Vapor Vents423
[118-120] [RESERVED]424
Section 3. FUEL SYSTEM COMPONENTS
[121-126] [RESERVED]445
127. FAR 25.1001 Fuel Jettisoning System445
Section 4. OIL SYSTEM [RESERVED]
Section 5. COOLING
[128-130] [RESERVED]481
Section 6. INDUCTION SYSTEM
131. FAR 25.1091 Air Induction497
132. FAR 25.1093 Induction System Icing Protection499
[133-136] [RESERVED]501
Section 7. EXHAUST SYSTEM
137. FAR 25.1121 General511
[138-140] [RESERVED] Section 8. POWERPLANT CONTROLS AND ACCESSORIES
[141-154] [RESERVED]521
Section 9. POWERPLANT FIRE PROTECTION
[155-158] [RESERVED]537
159. FAR 25.1187 Drainage and Ventilation of Fire Zones537
[160-164] [RESERVED]537
165. FAR 25.1197 Fire Extinguishing Agents537
[166-169] [RESERVED]538
CHAPTER 6. EQUIPMENT Section 1. GENERAL
170. FAR 25.1301 Function and Installation559
171. FAR 25.1303 Flight and Navigation Instruments592
172. FAR 25.1305 Powerplant Instruments [RESERVED]594
173. FAR 25.1307 Miscellaneous Equipment [RESERVED]594
174. FAR 25.1309 Equipment, Systems, and Installations594
Section 2. INSTRUMENTS: INSTALLATION
175. FAR 25.1321 Arrangement and Visibility [RESERVED]605
176. FAR 25.1322 Warning, Caution, and Advisory Lights [RESERVED]605
177. FAR 25.1323 Airspeed Indicating System605
178. FAR 25.1325 Static Pressure Systems608
179. FAR 25.1326 Pitot Heat Indicator Systems [RESERVED]609
180. FAR 25.1327 Magnetic Direction Indicator [RESERVED]609
181. FAR 25.1329 Automatic Pilot System609
Figure 181-1 Altitude Loss vs. Altitude Go-Around Mode617
[182-185] [RESERVED]625
Section 3. ELECTRICAL SYSTEMS AND EQUIPMENT
186. FAR 25.1351 General635
187. FAR 25.1353 Electrical Equipment and Installations637
188. FAR 25.1355 Distribution System639
189. FAR 25.1357 [RESERVED]639
190. FAR 25.1363 Electrical System Tests639
Section 4. LIGHTS
191. FAR 25.1381 Instrument Lights651
192. FAR 25.1383 Landing Lights651
193. FAR 25.1385 Position Light System Installation651
[194-200] [RESERVED]652
201. FAR 25.1401 Anticollision Light System652
202. FAR 25.1403 Wing Icing Detection Lights652
Section 5. SAFETY EQUIPMENT
[203-207] [RESERVED]659
Section 6. MISCELLANEOUS EQUIPMENT
208. FAR 25.1431 Electronic Equipment669
[209-223] [RESERVED]669
CHAPTER 7. OPERATING LIMITATIONS & INFORMATION Section 1. [RESERVED] Section 2. Operating Limitations [RESERVED] Section 3. Markings and Placards [RESERVED] Section 4. Airplane Flight Manual
224. FAR 25.1581 General679
[225-227] [RESERVED]679
CHAPTER 8. AIRWORTHINESS-MISCELLANEOUS ITEMS
228. Design and Function of Artificial Stall Warning and
Identification Systems701
229. Reduced and Derated Thrust Takeoff Operations704
230. Runway Gradients Greater than +2 Percent705
231. Performance Requirements for Flight in Icing Conditions707
232. Flying Qualities in Natural Icing Conditions708
233. Criteria for Approval of Steep Approach to Landing709
234. Takeoff and Landing on Unpaved Runways713
235. Accountability of Performance De gradation Relative Both Minor Design Changes (External Exposure) and
Configuration Deviation List (CDL) Items716
236. Configuration Deviation List (CDL)717
237. Spare Engine Pod 719
238. Authorization for Ferry Flight with One Engine Inoperative719
239. Instrument Landing System Weather Minima720
240. Takeoff Performance Credit for Alternate Forward Center of Gravity Limits721
241. Performance Credit for Automatic Propeller Drag Reduction Devices724
242. Airplane Backing Using Reverse Thru st725
APPENDICES Appendix 1 History of Jet Transport Performance Standards (CAR 4b Special Regulations 422, 422A and 422B) Appendix 2 History of Accelerate-Stop Transition Time Development Appendix 3 Correction of Air Minimum Control Speed (V MCA) to Standard Conditions Appendix 4 Rudder Pedal Force-Limited Air Minimum Control Speed (V MCA) Appendix 5 One-G Stall Compliance Basis Appendix 6 Sample Flight Test Program [RESERVED Appendix 7 FAA Handling Qualities Rating System Appendix 8 Functional and Reliability Tests (§ 21.35(b)(2))
CHAPTER 1 – GENERAL
1.-2. [RESERVED]
Chap 2 12 CHAPTER 2 - FLIGHT Section 1. GENERAL
3. PROOF OF COMPLIANCE - § 25.21.
a. Explanation. In an effort to provide the necessary guidelines for the flight test evaluation of transport category airplanes, without producing a cumbersome document, this advisory circular assumes a conventional transport airplane configuration. In general, a “conventional” airplane configuration is one with: distinct wing and fuselage elements that are joined together; aft-mounted horizontal and vertical stabilizers that are attached to the fuselage; and propulsion provided either by turbojet/turbofan engines that do not provide any significant increase in lift due to their operation or engine-driven propellers. The effects of non-conventional airplane configurations (e.g., blown flaps) on the compliance methods should be evaluated and determined based on the intent of the guidelines presented for conventional airplane configurations.
(1) Section 25.21(a) - Proof of Compliance.
(i) The burden of showing compliance with the flight requirements for an airworthiness certificate or a type certificate rests with the applicant. The applicant should, at his own expense and risk, conduct such official flight tests as required by the FAA to demonstrate compliance with the applicable requirements. During the certification process, the applicant should make available the airplane, as well as all of the personnel and equipment necessary to obtain and process the required data.
(ii) If the airplane flight characteristics or the required flight data are affected by weight and/or center of gravity (c.g.), the compliance data should be presented for the most critical weight and c.g. position. Unless it can be shown that the allowable c.g. travel in one or more axes (e.g., lateral fuel imbalance) has a negligible effect on the airworthiness requirements, compliance at the critical c.g. must be substantiated.
(iii) The gross weight and c.g. tolerances specified in paragraphs 3a(3)(ii)(A) and (D) are test tolerances and are not intended to allow compliance to be shown at less than critical conditions.
(iv) Section 25.21(a)(1) requires, in part, that the test airplane be in conformity with its type design specifications.
(A) This is interpreted as meaning the test airplane must be in conformity with its type design specification as relates to the particular test being conducted.
(B) Any deviation from conformity must be clearly shown to be of no consequence to the particular test being conducted. For example, if the slip resistant
Chap 2 13 escape surface required by §25.810(c) is not installed, it must be shown that its presence would have no effect on measured airplane performance and flight characteristics.
(2) Section 25.21(c) - Proof of Compliance (Altitude Effect on Flight Characteristics).
(i) Any of the flying qualities, including controllability, stability, trim, and stall characteristics, affected by altitude should be investigated for the most adverse altitude conditions approved for operations and limited, as appropriate, in accordance with § 25.1527.
(ii) Consideration should be given in the test program to aerodynamic control system changes with altitude (e.g., control throws or auto slats which are sometimes inhibited by Mach number at altitude).
(3) Section 25.21(d) - Proof of Compliance (Flight Test Tolerances).
(i) To allow for variations from precise test values, certain tolerances during flight testing should be maintained. The purpose of these tolerances is to allow for variations in flight test values from which data are acceptable for reduction to the value desired. They are not intended for tests to be routinely scheduled at the lower weights, or to allow for compliance to be shown at less than the critical condition; nor are they to be considered as allowable inaccuracy of measurement. As an example, when demonstrating stability with a specified trim speed of 1.4VS1, the trim speed may be
1.4VS1 +3 knots or 3 percent; however, no positive tolerance is permitted when demonstrating the minimum prescribed trim speed of 1.4VS1 (Ref. § 25.161).
(ii) Where variation in the parameter on which a tolerance is allowed will have an effect on the results of the test, the results should be corrected to the most critical value of that parameter within the operating envelope being approved. If such a correction is impossible or impractical (e.g., performance at forward c.g.), the average test conditions should assure that the measured characteristics represent the actual critical value.
(A) Weight limits. Figure 3-1, below, presents weight tolerances that have been found acceptable for the specified flight tests. Many flight tests need to be conducted at or very near the maximum operating weight for the airplane configuration, particularly those tests used to establish Airplane Flight Manual performance information. As noted in paragraph (i), above, the purpose of the test tolerances is to allow for variations in flight test values, not to routinely schedule tests at less than critical weight conditions or to allow for compliance to be shown at less that the critical weight condition.
Chap 2 14 FIGURE 3-1. WEIGHT TOLERANCE LIMITS Flight Test Conditions Weight Tolerance Limit +5% +10% Stall Speeds X Stall Characteristics X Climb Performance X Takeoff Flight Paths X Landing Braking Distance X Landing Air Distance X Takeoff Distance & Speed X Accelerate-Stop Distance X Maximum Energy RTOs X Minimum Unstick Speed X
(1) For follow-on airplane certification programs (e.g., minor gross weight increase), where it is desired to use an existing certificated data base from an aerodynamically similar model of the same airplane type, the test weight tolerance limits of Figure 3-1 have also been applied as extrapolation limits to minimize additional test requirements.
(2) For follow-on airplane certification programs, test data may be extrapolated to higher gross weights than specified in Figure 3-1, if the available test data includes an adequate range of weights and an appropriate number of points at the highest weight tested. If the test data analysis verifies the predicted effect of weight, then other extrapolation limits may apply.
(3) Equivalent weight extrapolation limits. For follow-on airplane certification programs where it is desired to increase a maximum operating weight based on existing certified performance parameters that have weight as one of their independent terms, those parameters should be examined for equivalent compliance with the weight tolerance limits of Figure 3-1. An example would be the reduction of an airplane's landing flap position, to one approved on a similar model of the same airplane type, which would incur an increase in landing speeds and brake energy, relative to the original certificated landing flap, at any given weight. The brake energy, at the maximum certificated landing weight, should be calculated for the reduced landing flap.
This brake energy should account for the increased landing speeds and reduced aerodynamic drag associated with the reduced flap setting. It should then be determined what "equivalent" gross weight would have rendered that brake energy with the original landing flap (see Figure 3-2). The resulting "equivalent" gross weight should not exceed the certificated maximum landing weight by more than the five percent weight extrapolation limit specified in Figure 3-1. If the "equivalent" gross weight (at the existing landing flap setting) is not more than five percent greater than the certificated
Chap 2 15 maximum landing weight, the reduced flap certification may be eligible for a limited flight test program (e.g., stall speed verification, handling characteristics, and qualitative landing demonstration). Further limitations may be imposed by the criteria of Technical Standard Order (TSO) C26c ("Aircraft Wheels and Wheel-Brake Assemblies, with Addendum I," dated May 18, 1984), wheel fusible plug energy limits, quick turnaround considerations, the maximum demonstrated kinetic energy level, wheel spin-up loads, etc.
FIGURE 3-2. EQUIVALENT WEIGHT EXTRAPOLATION (B) Wind Limits. For takeoff and landing tests, a wind velocity limit of 10 knots (from any direction) or 0.12VS1 (whichever is lower) at the height of the mean-aerodynamic-chord (MAC), as determined with the airplane in a static ground attitude, has been considered the maximum acceptable. When test wind velocity is to be measured at the wing MAC height, a measurement height of six feet above the ground should be considered as a limit to avoid possible measurement inaccuracies due to surface interference. Because of likely unsteady wind conditions, it is generally considered that takeoff and landing performance data obtained under runway wind conditions greater than 5 knots are likely to be inconsistent and unreliable. If performance data are obtained with winds greater than 5 knots, these data should not necessarily be ignored.
(C) C.G. Limits. A test tolerance of +7 percent of the total c.g. range is intended to allow some practical relief for inflight c.g. movement. This relief is only acceptable when the test data general scatter is on both sides of the limiting c.g. or when
c.g. correction from test c.g. to limit c.g. is acceptable.
(D) Airspeed Limits. Normally, tests conducted within 3 percent or 3 knots (whichever is the higher) of the desired test speed are considered acceptable.
Chap 2 16 (E) Thrust Limits. Thrust critical tests, such as minimum control speeds, should be conducted at the highest thrust (power) allowable on the engine given the constraints of temperature and altitude. It is then permitted to calculate further corrections to allow extrapolation of data to cover the entire operating envelope. These thrust corrections are limited to 5 percent of test day thrust, unless a detailed analysis is performed (see Appendix 3 of this AC).
(iii) Because the tolerance values normally are not considered in the airplane design substantiation, it is not the purpose of these tolerances to allow flights at values in excess of those authorized in the type design. If such flights are to be conducted, adequate structural substantiation for the flight conditions should be available.
These flights, however, are always conducted under controlled conditions and with the flight test crew's full cognizance of the situation. Examples of such flights are:
(A) Takeoff at greater than maximum takeoff weight for the purpose of reaching a test area at the maximum takeoff weight.
(B) Landing at greater than maximum landing weights during the course of conducting takeoff tests.
(C) Flights to obtain data for future approvals beyond that substantiated for the initial type design.
(iv) The table in Figure 3-3 indicates the cases in which corrections are normally allowed. Any corrections to flight test data should be made by methods that are agreed to by the FAA.
FIGURE 3-3. TEST PARAMETERS THAT NORMALLY CAN BE CORRECTED Flight Test Condition Correctable Parameters Wt. C.G. Airspeed Altitude Power/ Thrust Wind Airspeed calibration X --- --- --- --- --- Stall speeds X X --- --- X --- Climb performance X X X X X --- Landing performance X --- X X --- X Takeoff performance X X --- X X X Accelerate-stop perf. X X --- X X X Minimum control speed --- --- --- --- X --- Minimum unstick speed X X X --- X --- Buffet boundary X X --- X --- ---
(v) All instrumentation used in the flight test program should be appropriately calibrated and acceptable to the FAA test team.
Chap 2 17
(4) Section 25.21(f) - Proof of Compliance (Wind Measurement and Corrections). The relationship between the wind measured at one height and the corresponding wind at another height may be obtained by the following equation:
VW2 = VW1(H2/H1)1/7 Where: H = Height above the runway surface VW2 = Wind velocity at H2 VW1 = Wind velocity at H1 This equation is presented graphically below. Values of H less than 5 feet should not be used in this relationship.
FIGURE 3-4. WIND PROFILE VARIATION
(5) Wind Profile Variation for Test Data. The performance data of airplanes should be obtained in such a manner that the effect of wind on the test data may be determined. The test wind velocity should be corrected from the recorded height above the test surface to the height of the airplane wing mean-aerodynamic-chord. If the wind profile variation is not measured, the variation may be calculated using the equation in paragraph (4) above. The following examples are methods of handling wind profile variation data. Other methods have also been found acceptable.
0 10 20 30 40 50 60 70 0 10 20 30 40 50 60
WIND VELOCITY - KNOTS 10 meters
Chap 2 18 Example: Test Data Given:
o Height of mean-aerodynamic-chord with airplane on surface 8 ft.
o Height of wind measurement 6 ft.
o Measured wind velocity 4.8 kts.
Results:
o Test wind velocity with airplane 50 ft. above landing surface
4.8((50 + 8)/6)1/7 = 6.6 kts.
o Test wind velocity with airplane 35 ft. above takeoff surface
4.8((35 + 8)/6)1/7 = 6.4 kts.
o Test wind velocity with airplane on surface
4.8(8/6)1/7 = 5.0 kts.
(6) Wind Profile Variation for Airplane Flight Manual (AFM) Data. When expanding the data to the AFM conditions, the result should include the effective velocity, at the airplane's wing mean-aerodynamic-chord, which corresponds to the wind condition as measured at 10 meters (32.81 ft.) above the takeoff surface, and corrected for wind factors of § 25.105(d)(1).
Example: Airplane Flight Manual Data Given:
o Height of mean-aerodynamic-chord with airplane on surface 8.0 ft.
o Reported head wind at 10 meters 40.0 kts.
o Section 25.105(d)(1) wind factor 0.5 Results:
o Factored wind velocity with airplane 50 ft. above landing surface
(0.5)(40)((50 + 8)/32.81)1/7 = 21.7 kts.
o Factored wind velocity with airplane 35 ft. above takeoff surface
(0.5)(40)((35 + 8)/32.81)1/7 = 20.8 kts.
o Factored wind velocity with airplane on surface
(0.5)(40)(8/32.81)1/7 = 16.3 kts.
(7) Airplane Airspeed Variation Due to Wind Profile Variation With Simultaneous Speed Changes Due to Airplane Dynamic Performance. In the reduction of test data and in the expansion of such data to AFM conditions, the increase or decrease of speed due to the dynamic effect of the forces on the airplane are manifested by only the change in ground speed. These changes in speed (zero wind speed changes) may be