Special Conditions: Embraer S.A., Model EMB-550 Airplanes; Flight Envelope Protection: Normal Load Factor (g) Limiting
Federal Register, Volume 78 Issue 207 (Friday, October 25, 2013)
Federal Register Volume 78, Number 207 (Friday, October 25, 2013)
Proposed Rules
Pages 63902-63903
From the Federal Register Online via the Government Printing Office www.gpo.gov
FR Doc No: 2013-25204
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
Docket No. FAA-2012-0772; Notice No. 25-13-05-SC
Special Conditions: Embraer S.A., Model EMB-550 Airplanes; Flight Envelope Protection: Normal Load Factor (g) Limiting
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the Embraer S.A. Model EMB-550 airplane. This airplane will have a novel or unusual design feature associated with an electronic flight control system that prevents the pilot from inadvertently or intentionally exceeding the positive or negative airplane limit load factor. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These proposed special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.
DATES: Send your comments on or before December 9, 2013.
ADDRESSES: Send comments identified by docket number FAA-2013-0772 using any of the following methods:
Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending your comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S. Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, DC, between 8 a.m. and 5 p.m., Monday through Friday, except federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: The FAA will post all comments it receives, without change, to http://www.regulations.gov/, including any personal information the commenter provides. Using the search function of the docket Web site, anyone can find and read the electronic form of all comments received into any FAA docket, including the name of the individual sending the comment (or signing the comment for an association, business, labor union, etc.). DOT's complete Privacy Act Statement can be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov/ gov/.
Docket: Background documents or comments received may be read at http://www.regulations.gov/at any time. Follow the online instructions for accessing the docket or go to the Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except federal holidays.
FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Airplane and Flight Crew Interface Branch, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-2011; facsimile 425-227-1149.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite interested people to take part in this rulemaking by sending written comments, data, or views. The most helpful comments reference a specific portion of the special conditions, explain the reason for any recommended change, and include supporting data.
We will consider all comments we receive on or before the closing date for comments. We may change these special conditions based on the comments we receive.
Background
On May 14, 2009, Embraer S.A. applied for a type certificate for its new Model EMB-550 airplane. The Model EMB-550 airplane is the first of a new family of jet airplanes designed for corporate flight, fractional, charter, and private owner operations. The airplane has a conventional configuration with low wing and T-tail empennage. The primary structure is metal with composite empennage and control surfaces. The Model EMB-550 airplane is designed for 8 passengers, with a maximum of 12 passengers. It is equipped with two Honeywell HTF7500-E medium bypass ratio turbofan engines mounted on aft fuselage pylons. Each engine produces approximately 6,540 pounds of thrust for normal takeoff. The primary flight controls consist of hydraulically powered fly-by-wire elevators, ailerons, and rudders controlled by the pilot or copilot sidestick.
The design of the electronic flight control system for the Model EMB-550 airplane incorporates normal load factor limiting on a full time basis that prevents the flight crew from inadvertently or intentionally exceeding the positive or negative airplane limit load factor. This feature is considered novel and unusual in that the current regulations do not provide standards for maneuverability and controllability evaluations for such systems.
Type Certification Basis
Under the provisions of Title 14, Federal Code of Regulations (14 CFR) 21.17, Embraer S.A. must show that the Model EMB-550 airplane meets the applicable provisions of part 25, as amended by Amendments 25-1 through 25-127 thereto.
If the Administrator finds that the applicable airworthiness regulations (i.e., 14 CFR part 25) do not contain adequate or appropriate safety standards for the Model EMB-550 airplane because of a novel or unusual design feature, special conditions are prescribed under the provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which they are issued. Should the type certificate for that model be amended later to include any other model that incorporates the same or similar novel or unusual design feature, the special conditions would also apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special conditions, the Model EMB-550 airplane must comply with the fuel vent and exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36 and the FAA must issue a finding of regulatory adequacy under Sec. 611 of Public Law 92-574, the ``Noise Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR 11.19, in accordance with Sec. 11.38, and they become part of the type-
certification basis under Sec. 21.17(a)(2).
Page 63903
Novel or Unusual Design Features
The Model EMB-550 airplane will incorporate the following novel or unusual design features: The design of the electronic flight control system incorporates normal load factor limiting on a full-time basis that will prevent the flight crew from inadvertently or intentionally exceeding the positive or negative airplane limit load factor. This feature is considered novel and because the current regulations do not provide standards for maneuverability and controllability evaluations for such systems. Therefore, a special condition is needed to ensure adequate maneuverability and controllability when using this design feature.
Discussion
Title 14 Code of Federal Regulations (14 CFR) part 25 sections do not specify requirements or policy for demonstrating maneuver control that impose any handling qualities requirements beyond the design limit structural loads. Nevertheless, some pilots have become accustomed to the availability of this excess maneuver capacity in case of extreme emergency such as upset recoveries or collision avoidance.
As with previous fly-by-wire airplanes, the FAA has no regulatory or safety reason to prohibit a design for an electronic flight control system with load factor limiting. It is possible that pilots accustomed to this feature feel more freedom in commanding full-stick displacement maneuvers because of the following:
Knowledge that the limit system will protect the structure,
Low stick force/displacement gradients,
Smooth transition from pilot elevator control to limit control.
The special conditions will ensure adequate maneuverability and controllability when using this design feature.
Applicability
As discussed above, these special conditions are applicable to the Model EMB-550 airplane. Should Embraer S.A. apply at a later date for a change to the type certificate to include another model incorporating the same novel or unusual design feature, the special conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features on one model of airplanes. It is not a rule of general applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping requirements.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for Embraer S.A. Model EMB-550 airplanes.
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Flight Envelope Protection: Normal Load Factor (g) Limiting.
To meet the intent of adequate maneuverability and controllability required by Sec. 25.143(a), and in addition to the requirements of Sec. 25.143(a) and in the absence of other limiting factors, the following special conditions are proposed based on Sec. 25.333(b):
(a) The positive limiting load factor must not be less than:
(1) 2.5g for the normal state of the electronic flight control system with the high lift devices retracted.
(2) 2.0g for the normal state of the electronic flight control system with the high lift devices extended.
(b) The negative limiting load factor must be equal to or more negative than:
(1) Minus 1.0g for the normal state of the electronic flight control system with the high lift devices retracted.
(2) 0.0g for the normal state of the electronic flight control system with high lift devices extended.
(c) Maximum reachable positive load factor wings level may be limited by the characteristics of the electronic flight control system or flight envelope protections (other than load factor protection) provided that:
(1) The required values are readily achievable in turns, and
(2) That wings level pitch up is satisfactory.
(d) Maximum achievable negative load factor may be limited by the characteristics of the electronic flight control system or flight envelope protections (other than load factor protection) provided that:
(1) Pitch down responsiveness is satisfactory, and
(2) From level flight, 0g is readily achievable or alternatively, a satisfactory trajectory change is readily achievable at operational speeds. For the FAA to consider a trajectory change as satisfactory, the applicant should propose and justify a pitch rate that provides sufficient maneuvering capability in the most critical scenarios.
(e) Compliance demonstration with the above requirements may be performed without ice accretion on the airframe.
(f) These proposed special conditions do not impose an upper bound for the normal load factor limit, nor does it require that the limiter exist. If the limit is set at a value beyond the structural design limit maneuvering load factor n of Sec. Sec. 25.333(b), 25.337(b), 25.337 (c), there should be a very obvious positive tactile feel built into the controller so that it serves as a deterrent to inadvertently exceeding the structural limit.
Issued in Renton, Washington, on September 6, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
FR Doc. 2013-25204 Filed 10-24-13; 8:45 am
BILLING CODE 4910-13-P
