§ 23.397, Limit control forces and torques
§ 23.405, Secondary control system
§ 23.473, Ground load conditions and assumptions
§ 23.477, Landing gear arrangement
§ 23.479, Level landing conditions
§ 23.481, Tail down landing conditions
§ 23.483, One-wheel landing conditions
§ 23.485, Side load conditions
§ 23.493, Braked roll conditions
§ 23.505, Supplementary conditions for ski-planes
§ 23.521, Water load conditions
§ 23.561 Emergency Landing Conditions- General
§ 23.562, Emergency landing dynamic conditions
§ 23.601, Design and Construction- General
§ 23.603, Materials and workmanship
§ 23.613, Material strength properties and design values
§ 23.655, Control Surfaces- Installation
§ 23.955, Fuel flow
§ 23.959, Unusable fuel supply
§ 23.961, Fuel system hot weather operation
§ 23.991, Fuel pumps
§ 23.993, Fuel system lines and fittings
§ 23.995, Fuel valves and controls
§ 23.997, Fuel strainer or filter
§ 23.1019, Oil strainer or filter
§ 23.1121, Exhaust System- General
§ 23.1123, Exhaust system
§ 23.1182, Nacelle areas behind firewalls
§ 23.1183, Lines, fittings, and components
§ 23.1191, Firewalls
§ 23.1203, Fire detector system
§ 23.1505, Airspeed limitations
§ 23.1525, Kinds of operation
§ 23.1527, Maximum operating altitude
§ 23.1529, Instructions for Continued Airworthiness
§ 23.1541, Markings and Placards- General
§ 23.1543, Instrument markings: General
§ 23.1545, Airspeed indicator
§ 23.1547, Magnetic direction indicator
§ 23.1549, Powerplant and auxiliary power unit instruments
§ 23.1551, Oil quantity indicator
§ 23.1553, Fuel quantity indicator
§ 23.1555, Control markings
§ 23.1557, Miscellaneous markings and placards
§ 23.1559, Operating limitations placard
§ 23.1581, Airplane Flight Manual and Approved Manual material- General
§ 23.1583, Operating limitations
§ 23.1585, Operating procedures
Appendix F to Part 23, Test Procedure (Flammability)
11 Chapter 1 – Subpart D-Design and Construction
Section 1. Control Systems
23.671 General
No FAA policy is available as of December 31, 2007. EASA AMC effective November 13, 2003, AMC 23.671 is acceptable for FAA certification.
This rule was adopted on February 1, 1965 as a recodification of Civil Air Regulations (CAR), CAR 3.335.
23.672 Stability augmentation and automatic and power-operated systems
There are no corresponding rule or airworthiness criteria in CAR 3 or the Airship Design Criteria.
Amendment 23-45 and Subsequent
This rule is applicable only if the system is required to show compliance with the flight characteristic requirements of part 23.
This amendment adopted a proposed revision in NPRM 90-18 that stated: “This proposal would provide criteria for approval of those stability augmentation, automatic, and poweroperated systems whose performance is essential to flight safety. The proposed § 23.672 is similar to § 5.672 and, as part 25, the warning system requirement relating to control system activation is not intended to preclude installing tactile warning devices, such as control system shakers activated independently for other purposes.”
NOTE: Section 5.672 in above quote is incorrect. It should be § 25.672.
This requirement would not apply to a simple downspring or a bobweight stability device as affirmed by Final Rule, Docket 26269.
23.673 Primary flight controls
No policy available as of December 31, 2007.
The corresponding rule in CAR 3 is CAR 3.336.
23.675 Stops
No policy available as of December 31, 2007.
The corresponding rule in CAR 3 is CAR 3.340.
23.677 Trim Systems
The corresponding rule in CAR 3 is CAR 3.337.
The corresponding airworthiness criteria is section 4.16, Airship Design Criteria, FAA-P-8110-2, Change 2.
Original Issue and Subsequent
The trim system should prevent inadvertent, improper or abrupt trim operation. The direction of trim movement and its relation to its range of adjustment should be designed to prevent confusion.
Trim devices should be designed to continue normal operation with one failure of any connecting or transmitting element in the primary flight control system for (1) longitudinal trim in a single-engine airplane, and (2) longitudinal and directional trim in multiengine airplanes.
Amendment 23-7 and Subsequent
The amendment requires there be adequate control for safe flight and landing (rather than to “continue normal operation”) using the trim devices following the failure of a connecting/transmitting element in the primary controls. Thus, the control system element failure must not cause a failure of the trim system.
Failures of the trim system must not prevent safe flight and landing.
This amendment is clarified by Final Rule, Docket 8083 as follows: “The notice proposed to amend § 23.677 to make it clear that operation of the trim system may not be dependent upon the primary control system and that failures of the primary control system may not prevent safe flight and landing. Comments were received objecting to the proposal on the ground that it exceeded the part 25 requirements for transport category airplanes, and that it would improperly and undesirably change trim response and make compliance tests extremely hazardous. The FAA does not agree. The trim requirement is merely one of a number of control system requirements that must be considered as a total requirement. There is, therefore, no comparison between individual provisions in parts 23 and 25. Service experience with existing airplanes does not indicate that the proposal will improperly and undesirably change trim response or that compliance testing will be hazardous.
Furthermore, trim response equal to primary flight control response will not necessarily be needed to comply with the proposal. All that is required is that there be adequate control for safe flight and landing.”
16 Amendment 23-34 and Subsequent
Section 23.677(d) was added by Amendment 23-34 which was only applicable to commuter category airplanes.
Probable powered trim runaways should be demonstrated for all part 23 airplanes so equipped. See AC 23-8C, “Flight Test Guide for Certification of Part 23 Airplanes,” for the procedure.
Even if trim runaways have been determined to be unlikely using the guidance in AC 23.1309-1E, “System Safety Analysis and Assessment for Part 23 Airplanes,” appropriate trim runaway demonstrations in all axes are required to demonstrate the airplane has no unsafe features. The FAA has accepted demonstration of control-restrained trim runaways during malfunction testing for systems without a monitor/limiter regardless of the reliability and those with a monitor/limiter whose reliability is greater than probable. However, the FAA has determined this procedure is not acceptable in itself for failure conditions shown to be greater than major. To allow expansion of the 0 to 2g envelope, as specified in AC 23-8C, the FAA suggests a test procedure that incorporates both control restrained and unrestrained errors. The following test matrix considers the probability of trim runaways, high airframe limit loads, control stick/wheel configuration and absence of an autopilot system. Because rudder trim can be adjusted without the pilot directly in the control loop (that is, feet on the floor), restrained runaways for rudder trim are not considered acceptable. (See Table 1).
TABLE 1. TRIM SYSTEMS REQUIREMENTS
Maximum Maximum Force Maximum Axis Time Load (g) Attitude (restrained and Rate of Force (unrestrained) Change Unstrained) Change (unrestrained) (restrained)
Pitch recognition Structural +/-45 degrees 60 pounds 20 pounds/sec +3 seconds limits NTE
3.5g
Roll recognition Structural +/-90 degrees 30 pounds 10 pounds/sec +3 seconds Limits
Yaw recognition Structural +/-30 degrees 150 pounds N/A +3 seconds Limits (unrestrained only)
NOTE:
1. Restrained means the pilot is in the control loop (hands on) and unrestrained means the pilot is not in the control loop (hands off).
2. Trim systems with a monitor/limiter will be tested at a magnitude just below that required for monitor/limiter trip.
3. NTE is Not to Exceed.
Amendment 23-42 and Subsequent
This section was changed by Docket 25811, Amendment 23-42, as follows: This amendment extended the current requirements of Sec. 23.677 for powered trim system runaways to all categories of part 23 airplanes.
Amendment 23-49 and Subsequent
Final Rule 28506, Amendment 23-49, revised § 23.677(a) as follows:
NPRM 94-21 stated: “Proposed revised Sec. 23.677(a) would clarify the need to mark the lateral and directional trim indicators with the neutral trim position. Since trim indicators on most airplanes are currently marked with the neutral position of the trimming device, this proposal would standardize the cockpit markings for all airplanes.
Revised paragraph (a) would also add a requirement for the pitch trim indicator to be marked with the proper pitch trim range for the takeoff of the airplane. Some takeoff accidents, including some involving fatalities, have occurred because the pitch trim was not set to the proper range needed for the airplane takeoff. Because of this accident experience, most of the current airplane manufacturers mark the pitch trim indicator with the pitch trim range for takeoff. Therefore, the proposed marking requirement would not have a significant impact on future airplane designs and would ensure that the markings needed for a safe takeoff are provided for the pilots use.”
23.679 Control system locks
The corresponding rule in CAR 3 is CAR 3.341.
The corresponding airworthiness criteria is section 4.17, Airship Design Criteria, FAA-P-8110-2, Change 2.
Original Issue and Subsequent
Section 23.679(a) of part 23 and § 3.341(a) of the CAR require that if there is a device to lock the control system, there should be a means to give obvious warning to the pilot when the lock is engaged. Several accidents have occurred because the pilot did not remove the control system lock before takeoff. Many such accidents relate to internally applied locks, mostly pins installed at the control wheel column. Misuse and alteration of these installed locking devices, and neglect by the pilot to perform a control freedom check before takeoff, contributed to such accidents.
When evaluating a control lock system, the following factors should be considered in finding compliance with the applicable regulation:
a. The warning should be easily observable dur ing both day and night operations. Color, location, shape, and accessibility of the device, ease of removal with the pilot seated in the flying position, and legibility of any placards, etc., should be considered.
b. The system operation should be obvious. It s hould be possible to apply the lock only in such a manner that the required warning is provided.
c. When engaged, the lock should, by design, limit the operation of the airplane so the pilot receives unmistakable warning in the cockpit before or at the start of takeoff by an effective means, such as one of the following:
(1) Preventing the application of sufficient engine power to attempt a takeoff.
(2) Displacement of primary pilot controls, such as the control wheel full forward.
(3) An aural warning device that cannot be disengaged.
For airplanes with separate locks for throttle and control column, where one lock (for example, throttle) can be removed independently of the other, each lock should independently meet the criteria of § 23.679(c) above.
Amendment 23-45 and Subsequent
This amendment, changed by Final Rule, Docket 26269, states as follows: “The FAA is aware that an automatically released control lock system would be costly. The proposal did
19 not mandate the installation of an automatic system, but would add an optional provision that would show the acceptance of such systems.
The JAA stated its assumption that the proposed requirement would not be applicable to external locks. Based on the comments received, the FAA has re-examined the proposal.
Since the proposal would have eliminated the current Section 23.679(a), external systems that use the red warning ribbons as a means of warning the pilot that the locks are in place would no longer be acceptable. The FAA has determined that there is a need to retain the provision of current Section 23.679(a), so that presently used locks and their warning systems remain acceptable. The added provision of Section 23.679(a)(2) will make it clear that systems that automatically disengage the locks are also acceptable but not mandatory.
The proposal to limit the operation of the airplane when the locks are engaged is being restated since control locks and their warnings can be overlooked and automatic disengage systems will fail. The FAA believes an additional safeguard is required. By requiring a system that will ensure that airplane operation is limited, the pilot will receive a pre-takeoff warning and thus a hazardous takeoff will not be attempted.