89 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 airworthiness criteria is section 4.30, Airship Design Criteria, FAA-P-8110-2, Change 2.
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, FAA 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.
91 NOTE: FAA is not aware of any case where an applicant has used an analysis without testing, but will 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 in 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 airplanes operated above 25,000 feet in addition to the testing already required
92 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 in 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.”
The rule does not specify the icing conditions for which the windshield must provide adequate view. Since it is not reasonable to expect the critical conditions of the part 25, Appendix C icing envelope to be achieved in natural icing flight tests, an analysis validated by dry air testing should be accomplished to show the windshield heat is adequate in part 25, Appendix C icing conditions.
When determining adequate visibility during approaches, circling approaches should be evaluated.
EASA AMC effective February 12, 2009, 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 airworthiness criteria is section 4.31, Airship Design Criteria, FAA-P-8110-2, Change 2.
Original Issue and Subsequent
The FAA has no rule preventing placement of non-flight controls on control wheels, but will 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.
FAA strongly recommends that all redundant cockpit controls be symmetrical from one side of the cockpit to the other.
A proposed revision in 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. FAA 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 lever. The design feature of an SLPC was not envisioned by part 23/CAR 3. Further,
94 an SLPC cannot meet the standards imposed by §§ 23.777(d) and 23.781(b) as amended by Amendment 23-33. The current amendment level of part 23 (Amendment 23-53) contains regulations that allow evaluation of an SLPC without the need for Special Conditions (for example, §§ 23.777(a)(b), 23.779(b)(1),
23.1309). However, since an SLPC was not envisioned at the time Amendment 23- 33 was adopted, the question of compliance with §§ 23.777(d) and 23.781(b) as amended by Amendment 23-33 still exists.
Because of recommendations made by the NTSB, Amendment 23-33 provides specific location, height, and shape requirements for a number of cockpit controls, including power, propeller, and mixture controls. With the design feature of an SLPC integrating the functions of multiple controls into a single cockpit control, a nonstandardized design approach for the affected powerplant cockpit controls is used.
Additionally, § 23.1141(a) states as follows: “Powerplant controls must be located and arranged under § 23.777. However, an SLPC, as described earlier, cannot be arranged in accordance with § 23.777; therefore, compliance with § 23.1141(a) is not possible.”
Notice No. 84-12, the basis for Amendment 23-33, describes the intent of §§ 23.777
(d) and 23.781 (b). As stated in the notice:
"An effective means of enhancing pilot experience and training would be to require complete standardization in cockpit design. While such action may initially improve the level of safety, it might ultimately inhibit design advancement and result in lower levels of safety than would have evolved without such a total standardization.
An effective and practical means of enhancing the effectiveness of pilot training and enhancing safety would be to require standardization of location, shape, color, and direction of movement of those cockpit controls. This would have minimal adverse effect on design advancement."
From the preceding, obviously the FAA and industry did not envision or address the future use of an SLPC when drafting this rulemaking, but it was intended to allow design advancements that would improve safety. An SLPC is a design advancement in the public interest and does not adversely affect safety. Therefore, an SLPC will meet the intent, but not literal compliance, of §§ 23.777(d) and 23.781(b) as amended by Amendment 23-33.
The FAA, therefore, recommends use of an ELOS finding for airplanes with a certification basis of Amendment 23-33 or later when making compliance determinations for §§ 23.777(d) and 23.781(b). For these airplanes, Special Conditions are usually unnecessary. Sometimes, however, the applicable airworthiness standards may not be adequate because of other novel or unusual features of the aircraft, and Special Conditions may be warranted.
95 For airplanes with a certification basis prior to Amendment 23-33, no special considerations will be needed unless they involve other novel or unusual design features not covered by the applicable regulations.
The FAA has introduced regulatory action to revise part 23 to allow incorporation of an SLPC without special considerations. However, until these actions have been completed, the recommendations in this AC may be used for certification of an SLPC on part 23/CAR 3 airplanes.
Amendment 23-62 and Subsequent
In Docket No. FAA-2009-0738, the Discussion of the Regulatory Amendments stated: Current § 23.777 standardizes the height and location of powerplant controls because pilots may become confused and use the wrong controls on propeller-driven airplanes. This requirement, however, does not include single-power levers (which are typical for electronically-controlled engines). The FAA currently makes an ELOS finding for each airplane program that includes a single-power lever. FAA revised § 23.777(d) to incorporate the ELOS language.
This amendment changes § 23.777(d) to allow a single power lever installation without the need for an equivalent level of safety.
The Final Rule was modified by a comment that the requirement for power (thrust) levers should be easily distinguishable for human factor considerations instead of one inch higher than mixture and propeller levers. The FAA agrees with this comment and § 23.777 is adopted as modified.
23.779 Motion and effect of cockpit controls
The corresponding rule in CAR 3 is CAR 3.384.
The corresponding airworthiness criteria is section 4.32, Airship Design Criteria, FAA-P-8110-2, Change 2.
Original Issue—Reserved
The original rule only specified primary aerodynamic and throttle motion.
Amendment 23-33 and Subsequent
This amendment requires the propeller control should move forward to increase RPM. Therefore, a propeller pitch control on the vertical instrument panel does not comply. A switch found in a horizontal position with forward motion to increase RPM does comply. Other designs would have to be considered by an ELOS finding.
FAA would consider a propeller pitch control switch that would increase propeller RPM when moved to the “UP” position with a placard to show RPM change to be eligible as an equivalent.
FAA has no objection to the propeller pitch control switch being spring loaded against the fine and coarse propeller blade angles. The airplane should be evaluated to ensure no unsafe operating condition occurs with a propeller switch in each critical blade position.
See § 23.777 for guidance applicable to single power lever controls.
23.781 Cockpit control knob shape
The corresponding rule in CAR 3 is CAR 3.384.
There is no corresponding airworthiness criteria in the Airship Design Criteria.
Amendment 23-33 and Subsequent
This rule did not envision a single power lever installation. See § 23.777 for guidance applicable to single power lever controls.
23.783 Doors
The corresponding rule in CAR 3 is CAR 3.389.
The corresponding airworthiness criteria is section 4.33, Airship Design Criteria, FAA-P-8110-2, Change 2.
Original Issue and Subsequent
An ELOS finding process for part 23, § 23.783(b), should include:
a. Pilot operated locks when the propeller stops turning.
b. A special operating procedure to assure the door is opened only after the propeller has stopped turning should be provided in the flight manual and on the inside of the door.
c. If an electric lock is used, complete loss of electric power should not affect opening the door.
d. The door should be designed and placarded so it can be opened from the inside by passengers and from outside by ground personnel.
e. A railing or guard that would deploy to guide passengers away from the propeller plane should be provided as an integral part of the door.
f. If engagement of the engine starter would be an immediate hazard to a person near the propeller, an interconnection between the door and the engine starting circuit should be included in the design.
Amendment 23-34 and Subsequent The direct visual inspection of the locking mechanism by crewmembers to determine whether external doors, for which the initial opening movement is outward, are fully closed and locked may be conducted from outside the airplane. It will be necessary to provide a means to inspect each individual lock of the locking mechanism. Means that do not allow direct visual inspection of each lock are unacceptable unless there is no failure mode of the locking mechanism that would allow a false visual indication that each latch is properly positioned and locked. If optical devices are used from either inside or outside, it should be determined that they are not subject to fogging, to obstruction by foreign objects, or to a false indication of a locked condition. The locking mechanism should incorporate features that provide a positive means to prevent the door from vibrating open throughout the approved operating envelope.
Over center features of the mechanism are not acceptable as a locking means. Also, it should not be possible to position the locks in a locked position if any of the latches are not in the fully latched position.
99 Amendment 23-36 and Subsequent Section 23.783(c) was adopted to provide standards that would assure the opening means of passenger and crew doors were simple, easy to find, and could be operated in darkness. It also assured the doors met particular marking requirements. Overly complex opening means had been identified as a major contributor in accident investigations. The particular marking means are those of § 23.811. § 23.783(c)(3) was adopted mainly as a measure to ensure the opening means of passenger and crew doors were kept as simple as possible, and that these doors could be found and opened in a timely manner. § 23.783(c)(4) was adopted to make the location of cabin doors more conspicuous and to facilitate emergency evacuation.
These requirements do not mandate the use of self-illuminated or electrically illuminated external markings. A reasonable and acceptable method of compliance can be found in § 23.807 by substituting “passenger or crew door” where reference is made to “emergency exit.”
This amendment added a requirement that doors be reasonably free of jamming from fuselage deformation from the ultimate load factors found in the General Requirements for Emergency Landing Conditions (§ 23.561) and the limit Proof of Structure (§ 23.307(a)). Some applicants choose ultimate Proof of Structure loads as a higher level of safety than proposed here. Methods used to show compliance with these requirements should include:
A determination from tests that each emergency door can be opened from inside and outside the airplane after imposing each critical static test load condition from the following limit flight and ground design load requirements (provided they equal or exceed the Emergency landing Conditions).
FLIGHT LOADS
General (§ 23.321) Symmetrical flight conditions (§ 23.331) Flight envelope (§ 23.333) Design airspeeds (§ 23.335) Limit maneuvering load factors (§ 23.337) Gust load factors (§ 23.341) Pressurized cabin loads (for flight, § 23.365(a) and (b); and for landing, § 23.365(a) and (c))
GROUND LOADS
General (§ 23.471) Ground load conditions and assumptions (§ 23.473) Landing gear arrangement (§ 23.477) Level landing conditions (§ 23.479)
100 Tail down landing conditions (§ 23.481) One-wheel landing conditions (§ 23.483) Side load conditions (§ 23.485).
Amendment 23-49 and Subsequent This amendment adds a requirement that passenger doors not be located with any other potential hazard as well as the propeller disk. These hazards could include hot anti-ice, hot de-ice surfaces, and sharp objects on the airplane structure.
EASA AMC effective February 12, 2009, AMC 23.783(b) is acceptable for FAA certification.