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Chapter 2. POWERPLANT
Section 1. GENERAL
42. Section 25.943 Negative acceleration 117
a. Rule Text 117
Section 2. FUEL SYSTEM COMPONENTS
43. Section 25.1001 Fuel jettisoning system 119
a. Rule Text 119
Section 3. POWERPLANT FIRE PROTECTION
44. Section 25.1183 Flammable fluid-carrying components 121
a. Rule Text 121
45. Section 25.1185 Flammable fluids 122
a. Rule Text 122
46. Section 25.1189 Shutoff means 122
a. Rule Text 122
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Chapter 3. EQUIPMENT
Section 1. GENERAL
47. Section 25.1301 Function and installation 125
a. Rule Text 125
b. Intent of Rule 125
c. Background 125
(1) Harmonization 125
d. Policy/Compliance 125
(1) JAR ACJ 25.1301(b) 126
e. Reference 126
48. Section 25.1309 Equipment, systems, and installations 126
a. Rule Text 126
b. Intent of Rule 127
c. Background 127
(1) Amendment 25-23 128
(2) Amendment 25-38 128
(3) Amendment 25-41 128
(4) Harmonization 128
d. Policy/Compliance 128
(1) Probability of a fire 128
(2) Examples 130
(3) Safe and reliable 130
e. References 130 [49-51] [RESERVED] 130
Section 2. INSTRUMENTS: INSTALLATION
52. Section 25.1325 Static pressure systems 131
a. Rule Text 131
b. Intent of Rule 132
c. Background 132
(1) Amendment 25-5 132
(2) Amendment 25-12 132
(3) Amendment 25-41 132
d. Policy/Compliance 132
e. Reference 132
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Section 3. SAFETY EQUIPMENT
53. Section 25 1419 Ice protection 133
a. Rule Text 133
b. Intent of Rule 133
c. Background 133
(1) Amendment 25-23 134
(2) Amendment 25-72 134
d. Policy/Compliance 134
e. References 134 [54-58] [RESERVED] 134
Section 4. MISCELLANEOUS EQUIPMENT
59. Section 25.1433 Vacuum systems 135
a. Rule Text 135
b. Intent of Rule 135
c. Background 135
(1) Amendment 25-72 135
d. Policy/Compliance 135
e. References 135
60. Section 25.1435 Hydraulic systems 135
a. Rule Text 135
b. Intent of Rule 136
c. Background 137
(1) Amendment 25-13 137
(2) Amendment 25-23 138
(3) Amendment 25-41 138
(4) Amendment 25-72 138
(5) Exemptions 138
(6) Harmonization 139
d. Policy/Compliance 139
(1) Hydraulic fluid contamination 139
(2) Certification of hydraulic lines for temporary repairs 140
(3) Use of hydraulic lines for temporary repairs 141
(4) Hydraulic system certification philosophy 142
(5) Interpretation of § 25.1435(a)(4) of 14 CFR 143
e. References 144
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61. Section 25.1438 Pressurization and pneumatic systems 145
a. Rule Text 145
b. Intent of Rule 145
c. Background 145
(1) Harmonization 145
d. Policy/Compliance 145
(1) Pneumatic versus pressurization system identification 145
e. References 146
62. Section 25.1439 Protective breathing equipment 146
a. Rule Text 146
b. Intent of Rule 147
c. Background 148
(1) Amendment 25-38 148
d. Policy/Compliance 148
(1) Protective breathing equipment usage when approved under TSO-C99 and TSO-C116 148
(2) Protective breathing equipment serviceability 149
(3) Protective breathing equipment on the flight deck 149
(4) Definition of terms used in § 25.1439 150
e. References 151
63. Section 25.1441 Oxygen equipment and supply 151
a. Rule Text 151
b. Intent of Rule 151
c. Background 151
d. Policy/Compliance 151
(1) Compliance with §§ 25.1309(c) and 25.1441(c) 151
(2) Guidance, availability of flightcrew oxygen 153
(3) Oxygen installation for medical use 155
e. Reference 156
64. Section 25.1443 Minimum mass flow of supplemental oxygen 156
a. Rule Text 156
b. Intent of Rule 157
c. Background 157
d. Policy/Compliance 157
e. Reference 157
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65. Section 25.1445 Equipment standards for the oxygen distributing system 158
a. Rule Text 158
b. Intent of Rule 158
c. Background 158
d. Policy/Compliance 158
e. Reference 158
66. Section 25.1447 Equipment standards for oxygen dispensing units 158
a. Rule Text 158
b. Intent of Rule 160
c. Background 160
(1) Amendment 25-41 160
(2) Amendment 25-87 160
d. Policy/Compliance 160
(1) Oxygen equipment for forward observer's position 160
e. References 161
67. Section 25.1449 Means for determining use of oxygen 161
a. Rule Text 161
b. Intent of Rule 161
c. Background 161
d. Policy/Compliance 162
(1) Oxygen equipment for observer's position 162
(2) Determination of passenger oxygen supply 163
e. References 163
68. Section 25.1450 Chemical oxygen generators 163
a. Rule Text 163
b. Intent of Rule 164
c. Background 164
d. Policy/Compliance 164
e. Reference 164
69. Section 25.1453 Protection of oxygen equipment from rupture 164
a. Rule Text 164
b. Intent of Rule 164
c. Background 164
d. Policy/Compliance 164
(1) Flexible plastic oxygen lines 165
(2) Use of plastic oxygen lines 165
e. Reference 166
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70. Section 25.1455 Draining of fluids subject to freezing 166
a. Rule Text 166
b. Intent of Rule 166
c. Background 166
(1) Amendment 25-23 167
d. Policy/Compliance 167
e. Reference 167
71. Section 25.1461 Equipment containing high energy rotors 167
a. Rule Text 167
b. Intent of Rule 167
c. Background 168
(1) Amendment 4b-8 (CAR) 168
(2) Amendment 4b-12 (CAM) 168
(3) Amendment 25-41 168
d. Policy/Compliance 168
e. Reference 168
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Chapter 4. OPERATING LIMITATIONS AND INFORMATION
Section 1. OPERATING LIMITATIONS
72. Section 25.1529 Instructions for continued airworthiness 169 H25.4 airworthiness limitations section 169
a. Rule Text 169
b. Intent of Rule 169
c. Background 169
d. Policy/Compliance 170
e. Reference 170
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APPENDICES
Appendix Subject
1. Cross reference for selected sections of part 25, 171 Section 4b of the civil air regulations (CAR) and Section 4b of the civil aeronautics manual (CAM)
2. Glossary of acronyms 172
3. Index of advisory circular references 173
4. Index of incorporated guidance material and references 178
(1) FAA memorandums and letters 178
(2) FAA technical standard orders (TSO) 181
(3) FAA orders 182
(4) FAA videos 182
(5) Society of Automotive Engineers (SAE) documents 183
(6) Miscellaneous references 186
(7) Cross reference to other AC handbooks 189
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Chapter 1. DESIGN AND CONSTRUCTION
Section 1. CONTROL SYSTEMS
1. SECTION 25.671 - GENERAL.
a. Rule Text.
(a) Each control and control system must operate with the ease, smoothness, and positiveness appropriate to its function.
(b) Each element of each flight control system must be designed, or distinctively and permanently marked, to minimize the probability of incorrect assembly that could result in the malfunctioning of the system.
(c) The airplane must be shown by analysis, tests, or both, to be capable of continued safe flight and landing after any of the following failures or jamming in the flight control system and surfaces (including trim, lift, drag, and feel systems), within the normal flight envelope, without requiring exceptional piloting skill or strength. Probable malfunctions must have only minor effects on control system operation and must be capable of being readily counteracted by the pilot.
(1) Any single failure, excluding jamming (for example, disconnection or failure of mechanical elements, or structural failure of hydraulic components, such as actuators, control spool housing, and valves).
(2) Any combination of failures not shown to be extremely improbable, excluding jamming (for example, dual electrical or hydraulic system failures, or any single failure in combination with any probable hydraulic or electrical failure).
(3) Any jam in a control position normally encountered during takeoff, climb, cruise, normal turns, descent, and landing unless the jam is shown to be extremely improbable, or can be alleviated. A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable.
(d) The airplane must be designed so that it is controllable if all engines fail.
Compliance with this requirement may be shown by analysis where that method has been shown to be reliable.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 35 FR 5674, Apr. 8, 1970]
NOTE: This regulation is the subject of a Federal Aviation Regulations/Joint Aviation Requirements (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group may recommend revisions to §§ 25.671 and 25.672. The ARAC working group is developing Advisory Circular (AC) 25.671-1.
2. SECTION 25.672 - STABILITY AUGMENTATION AND AUTOMATIC AND POWER-OPERATED SYSTEMS.
a. Rule Text.
If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show compliance with the flight characteristics requirements of this part, such systems must comply with § 25.671 and the following:
(a) A warning which is clearly distinguishable to the pilot under expected flight conditions without requiring his attention must be provided for any failure in the stability augmentation system or in any other automatic or power-operated system which could result in an unsafe condition if the pilot were not aware of the failure. Warning systems must not activate the control systems.
(b) The design of the stability augmentation system or of any other automatic or power-operated system must permit initial counteraction of failures of the type specified in § 25.671(c) without requiring exceptional pilot skill or strength, by either the deactivation of the system, or a failed portion thereof, or by overriding the failure by movement of the flight controls in the normal sense.
(c) It must be shown that after any single failure of the stability augmentation system or any other automatic or power-operated system-
(1) The airplane is safely controllable when the failure or malfunction occurs at any speed or altitude within the approved operating limitations that is critical for the type of failure being considered;
(2) The controllability and maneuverability requirements of this part are met within a practical operational flight envelope (for example, speed, altitude, normal acceleration, and airplane configurations) which is described in the Airplane Flight Manual; and
(3) The trim, stability, and stall characteristics are not impaired below a level needed to permit continued safe flight and landing.
[Amdt. 25-23, 35 FR 5675, Apr. 8, 1970]
NOTE: This regulation is the subject of a Federal Aviation Regulations/Joint Aviation Requirements (FAR/JAR) harmonization effort under the Aviation Rulemaking Advisory Committee (ARAC). The ARAC working group may recommend revisions to §§ 25.671 and 25.672. The ARAC working group is developing AC 25.671-1.
NOTE: For policy and guidance on compliance with this requirement, refer to AC 25.672-1, Active Flight Controls.
3. SECTION 25.699 - LIFT AND DRAG DEVICE INDICATOR.
a. Rule Text.
(a) There must be means to indicate to the pilots the position of each lift or drag device having a separate control in the cockpit to adjust its position. In addition, an indication of unsymmetrical operation or other malfunction in the lift or drag device systems must be provided when such indication is necessary to enable the pilots to prevent or counteract an unsafe flight or ground condition, considering the effects on flight characteristics and performance.
(b) There must be means to indicate to the pilots the takeoff, en route, approach, and landing lift device positions.
(c) If any extension of the lift and drag devices beyond the landing position is possible, the controls must be clearly marked to identify this range of extension.
[Amdt. 25-23, 35 FR 5675, Apr. 8, 1970]
b. Intent of Rule. This rule prescribes standards for providing visual indication to the pilot of the high lift and drag device(s) surface positions for the takeoff, enroute, approach, and landing conditions.
c. Background. Effective February 1, 1965, part 25 was added to Title 14, Code of Federal Regulations (14 CFR), to replace part 4b of the Civil Air Regulations (CAR). Sections 4b.323(e) and 4b.323(f) of the CAR basically covered trailing edge devices. These sections became §§ 25.699(a) and 25.699(b) of 14 CFR for wing flap position indicator.
(1) Amendment 25-23 (April 8, 1970) expanded the rule to specifically cover all high drag devices or high lift devices (such as slots, spoilers, and slats), and added the requirement for position indication for all lift and drag devices with separate cockpit controls. The title was revised accordingly.
d. Policy/Compliance Methods. Indicators that show the position of the lift or drag devices must be provided. If asymmetric extension of lift or drag devices could result in an unsafe condition, an indication of each individual control surface is required. The indication must clearly identify each position setting. The controls should be designed so that inadvertent extension beyond the landing position is not possible. For guidance on compliance with this requirement, refer to AC 25-14, dated 5/4/88, which is incorporated below.