23.745 Nose/tail wheel steering
No policy available as of September 30, 2003.
There is no corresponding rule in CAR 3 or the Airship Design Criteria.
FLOATS AND HULLS
23.751 Main float buoyancy
The corresponding rule in CAR 3 is CAR 3.371.
There is no corresponding rule in the Airship Design Criteria.
Original Issue and Subsequent
For a twin float seaplane or amphibian aircraft, the 80 percent excess buoyancy requirement should be applied to both rather than each float.
The rules for twin float aircraft do not address water stability or capsizing. They only require the aircraft remain afloat with any two compartments of the main floats flooded. The history does not support the position the aircraft will remain afloat indefinitely without capsizing with two compartments flooded. However, if an unsafe condition exists, certification should be denied under part 21, § 21.21(b)(2).
An example of an unsafe condition could be capsizing so rapidly the occupants could not safely exit. Capsizing that is delayed long enough to permit taxi to the shore or dock is not an unsafe condition. The time to capsize should be listed in the Emergency Procedures Section of the AFM.
Amendment 23-45 and Subsequent
A revision to NPRM 90-18 explains this amendment as follows: “This proposal revises Section 23.751 to clarify the buoyancy requirements for main floats in paragraph (a)(1) by specifying an 80 percent excess in buoyancy for each main float above the buoyancy required by that float to support the maximum weight of the seaplane. Additionally, the words "without capsizing" are added to paragraph (a)(2) to clarify the extent of flotation necessary after main float compartment flooding.
A strict interpretation of existing Section 23.751(a)(1) results in a buoyancy excess of 80 percent of the maximum weight of the seaplane when the design consists of only one main float, or a total of 180 percent of the maximum weight. However, on seaplanes having two main floats, each float would be required to have buoyancy of 80 percent in excess of that necessary to support the seaplane, or 180 percent of the maximum weight of the seaplane; for a total of 360 percent of the maximum weight.
For designs having three floats, each float would be required to support 180 percent of the maximum weight for a total of 440 percent. This is neither the intent of the rule nor the practice of industry.
The change to paragraph (a)(2) is intended to clarify the fact that the seaplane be afloat in the upright condition.”
23.753 Main float design
No policy available as of September 30, 2003.
There is no corresponding rule in CAR 3 or the Airship Design Criteria.
23.755 Hulls
The corresponding rule in CAR 3 is CAR 3.372.
There is no corresponding rule in the Airship Design Criteria.
Original Issue
The discussion on capsizing and unsafe conditions in § 23.751 applies to this rule also.
Amendment 23-45 and Subsequent
This amendment changed the rule to prohibit capsizing in fresh water for planes over 5,000 pounds with two adjacent compartments flooded, and those between 1,500 and 5,000 pounds with any single compartment flooded.
23.757 Auxiliary floats
No policy available as of September 30, 2003.
This rule was adopted on February 1, 1965 as a recodification of CAR 3.373.
There is no corresponding rule in the Airship Design Criteria.
PERSONNEL AND CARGO ACCOMMODATIONS
23.771 Pilot compartment
No policy available as of September 30, 2003.
The corresponding rule in CAR 3 is CAR 3.381.
The corresponding rule in the Airship Design Criteria, FAA-P-8110-2, Change 2, is section 4.28.
23.773 Pilot compartment view
The corresponding rule in CAR 3 is CAR 3.382.
The corresponding rule in the Airship Design Criteria, FAA-P-8110-2, Change 2, is section .29.
Amendment 23-14 and Subsequent
See AC 23-8B, “Flight Test Guide for Certification of Part 23 Airplanes,” for guidance on this regulation. EASA AMC 23.773 references the CS-23 Flight Test Guide.
Amendment 23-45 and Subsequent
A proposed revision to NPRM 90-18 explains the rewrite of this section as follows:
“This proposal is based in part on conference recommendation 272, on conference comments, and on a post conference review of the adequacy of previous certifications, which establishes a precedent for compliance with existing Section
23.773. It is not the intent of this proposal to require windshield heat on all small airplanes, to preclude open cockpit designs or to prohibit the pilot from using a cloth to wipe the windows. It does, however, define requirements to assure that a means exists to remove or prevent the formation of fog or frost on the inside of the windshield, specifies the extent of credit to be given to pilot actions and defines the area of windshield and windows to be kept clear.
Paragraph (a)(1) of this proposal requires an extensive, clear, and undistorted view sufficient to enable the pilot to perform any maneuvers within the operating limitations of the airplane, and specifies particular operations, such as taxi, takeoff, approach and landing to clarify the extent of view necessary for safe operation.
Paragraph (b) of this proposal is included to address the condition where an airplane is operated at high altitudes, becomes cold-soaked, and is then descended into warm, moist air. Such conditions have resulted in the formation of frost on the inside surface of the windshield and crew compartment windows, which resulted in a limited or completely obscured view. Since, in such cases, compliance has been shown for the current Section 23.773(a)(3), a rule change is appropriate to address this condition. The FAA proposes to revise Section 23.773 to identify this condition and to clarify the extent of actions taken by the pilot to remove such moisture.”
The Final Rule 26269 for Amendment 23-45 states as follows: “The FAA proposed to revise the 23.773 requirements for the pilot compartment view to address the environment expected in all the operations requested for certification. The JAA states that it will consider this change for JAR 23 but that it proposes to retain present paragraph (b) relating to night flight tests. The GAMA contends that the words 92
"must be shown in all operations for which certification is requested," could be interpreted to mean that the same view must be provided for all operations.
The FAA does not agree with the GAMA interpretation. Section 23.773(a) and (a)(1) require the pilot compartment view to be sufficiently extensive, clear, and undistorted to allow the pilot to perform the various functions identified in this proposal. The word "sufficiently" is included because the FAA recognizes that the view needed for one operation may differ from the view needed for another. The intent is also shown by the words "sufficiently large" used in Section 23.773(b). The FAA adopts Section
23.773 as proposed.”
23.775 Windshields and windows
The corresponding rule in CAR 3 is CAR 3.383.
The corresponding rule in the Airship Design Criteria, FAA-P-8110-2, Change 2, is section 4.30.
Original Issue and Subsequent
The rule requires the Luminous Transmittance (LT) be no less than 70 percent when the pilot is seated in a normal flight position. This rule does not specify how the LT is to be measured. Industry, federal practices, standards and airframe manufacturer specifications have specified a minimum LT measurement for Federal Standard 406, Method 3022 or equivalent.
Based on available data, we cannot determine that an LT of 70 percent is in itself an unsafe condition. There are other factors such as windshield/window inclination from vertical. The criterion to determine an unsafe condition is a qualitative pilot evaluation.
Nonsplintering material in this section refers to materials such as safety glass, which shatter into small fragments that can cause superficial injuries. Splintering materials are those that shatter into slivers, which can result in serious injuries.
Policy for 14 CFR, part 23, § 23.775, Temperature and Temperature Gradient Requirement Certification:
Section 23.775 requires the following:
- “The design of windshields, windows, and canopies in pressurized airplanes must be based on factors peculiar to high altitude operation, including – The effects of temperatures and temperature gradients;” and
- “If certification for operation above 25,000 feet is requested, the windshield, window panels, and canopies must be strong enough to withstand the maximum cabin differential loads combined with critical aerodynamic pressure and temperature effects, after failure of any load-carrying element of the windshield, window panel, or canopy.”
On-airplane testing is one acceptable Means of Compliance (MOC) to these requirements. Other acceptable MOCs are component level testing, a combination of tests and analyses, or an analysis based on known temperature and temperature gradient effects for a specific material and installation. Qualification by similarity is also acceptable.
NOTE 12: We are not aware of any case where an applicant has used an analysis without testing, but we should consider this if an applicant proposes it.
The testing or analysis would have to consider pressurization loads or fail-safe loads with the temperature and temperature gradient effects. These would be in addition to the cyclic or fail-safe testing of the complete pressure cabin at ambient temperature.
Current practice is to superimpose the pressure loading and the thermal gradients in a test. The testing and conditions vary from full-scale test articles with environmental chambers around the windows and windshields to component tests. For fail-safe requirements, most manufacturers are using a “failed” article (cut before test) while running a test to fail-safe loads or better.
If the bird strike requirements in § 23.775(h)(1) are applicable (Amendment 23-49), the applicant should consider the effects of temperature and temperature gradients when showing compliance to the two-pound bird strike.
Amendment 23-7 and Subsequent
A proposed revision to NPRM 67-14 explains this amendment as follows: “Sudden decompression of small cabins due to transparency failure is potentially catastrophic.
Experience with transport category airplanes has shown that decompression has been averted in several cases because of the dual element design of transparencies.
The value 25,000 feet is believed to represent a reasonable point of demarcation between the altitudes at which sudden decompression is and is not potentially catastrophic, considering the expected cabin sizes and operating altitudes of small airplanes.”
The preamble material for Final Rule, Docket 8083 is explained as follows: “The notice proposed to add a new Sec. 23.775(e) imposing a fail-safe requirement for windshields, window panels, and canopies of airplanes certificated for operation above 25,000 feet. One comment objected, stating that the proposed requirement is unnecessary and an arbitrary dictation of design; that windshields should not be singled out over control systems or other components, and that transport category airplane decompression experience does not apply to Part 23 airplanes because the differential pressures are not the same. Commentator also suggested that if the proposal is adopted, the prescribed load should be the ultimate load. The FAA does not agree. Windshield strength cannot be controlled to the same degree of precision as is achieved with other materials, consequently redundancy is particularly important. Part 23 airplanes operate at the same altitudes as transport airplanes, where windshields have been lost and where windshield failure can be extremely hazardous. There is no justification for Part 23 design standards for windshields to be lower than those required in Part 25. The prescribed loading cannot be considered the ultimate load because a partially failed windshield would have essentially no factor of safety. Another comment objected to the proposal because paragraph (e) would require a fail-safe determination for all canopies of pressurized 95
airplanes operated above 25,000 feet in addition to the testing already required under present paragraph (c). The intent of the proposal is to require airplanes certificated for operations above 25,000 feet to comply with the requirements of proposed paragraph (e) instead of the requirements of current paragraph (c), and paragraph (c) is amended to limit its applicability to pressurized airplanes that do not comply with the fail-safe requirements of paragraph (e). Except for this change the amendment is adopted as proposed.”
Amendment 23-45 and Subsequent
A proposed revision to NPRM 90-18 explains a change to this amendment as follows:
“This proposal is intended to clarify the criteria for determining the cleared windshield area the FAA deems necessary to assure safe operation for icing certification. By specifically identifying the operational phases of takeoff, approach, landing, and taxi, this proposal is intended to prevent the past practice of certifying airplanes for operation in known icing conditions, with panels too small and too far in front of the pilot (in some cases, a single small panel centered on the windshield to be used from either pilot seat) to allow full operation of the airplane. In such cases, the runway is not always visible during approach when crosswinds result in large crab angles. Additionally, upon landing, the ability to locate and safely use taxiways is hampered because of the restricted view available to the pilot through the small panel. This proposal is not intended to preclude the use of such panels, but does identify the criteria for determining the size, location, and, if necessary, the number of panels.
In addition, a proposal is made to require that the probable single failure of transparency heating systems not adversely affect the integrity of the airplane cabin.
Such failures do occur and consideration of such occurrences is necessary as a minimum requirement for the type certification of new airplane designs.”
EASA AMCs 23.775(f) and 23.775(g), which apply to § 23.775(g) and (h) in 14 CFR, part 23, are acceptable for FAA certification.
23.777 Cockpit controls
The corresponding rule in CAR 3 is CAR 3.384.
The corresponding rule in the Airship Design Criteria, FAA-P-8110-2, Change 2, is section 4.31.
Original Issue and Subsequent
The FAA has no rule preventing placement of non-flight controls on control wheels, but we consider such installations to be marginal since a switch could easily be confused with microphone or autopilot switches. Approval would require special crew training and AFM guidance to ensure it was used properly.
We strongly recommend that all redundant cockpit controls be symmetrical from one side of the cockpit to the other.
A proposed revision to NPRM 67-14 added a requirement under Amendment 23-7 about fuel selectors. The explanation in the NPRM reads as follows: “Proper fuel management requires that the pilot be able to reach the fuel selector, at any time, without being forced to move the seat or the primary controls (which may be hazardous at low altitudes). Ability to reach the fuel selector under any condition requires that each selector be visible to the pilot with the seat in any normal inflight position.”
Amendment 23-33 and Subsequent
This amendment added § 23.777(c)(4). It requires that airplanes with side-by-side pilot seats and two sets of powerplant controls, have one set on the left console and one set on the right console. We will consider an ELOS finding for airplanes with one set on the left hand side and one on or near the cockpit centerline.
The preamble to Amendment 23-33 shows that floor mounted, mechanical flap controls are acceptable.
14 CFR part 23/CAR 3 Airplanes; Clarification of Type Certification Process of Single Lever Power Controls (SLPCs)
The purpose of this guidance is to provide recommendations for certification of SLPC installed in part 23/CAR 3 airplanes.
There are airplanes certificated or currently undergoing certification that have combined the features of two or more of the cockpit powerplant controls for power (thrust), propeller (Revolutions Per Minute (RPM) control), and mixture control (condition lever and fuel cutoff for turbine powered airplanes) into a single power 97