Special Conditions: Embraer S.A., Model EMB-550 Airplanes; Flight Envelope Protection: Normal Load Factor (g) Limiting, 20768-20769 [2014-08275]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 79, Number 71 (Monday, April 14, 2014)]
[Rules and Regulations]
[Pages 20768-20769]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-08275]



[[Page 20768]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0772; Special Conditions No. 25-520-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: Final special conditions.

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SUMMARY: These special conditions are issued 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 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: Effective Date: May 14, 2014.

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:

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).

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 because the current regulations do not 
provide standards for maneuverability and controllability evaluations 
for such systems. Therefore, special conditions are needed to ensure 
adequate maneuverability and controllability when using this design 
feature.

Discussion

    Title 14, Code of Federal Regulations, 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.
    These special conditions will ensure adequate maneuverability and 
controllability when using this design feature.

Discussion of Comments

    Notice of proposed special conditions No. 25-13-05-SC for Embraer 
S.A. Model EMB-550 airplanes was published in the Federal Register on 
October 25, 2013 (78 FR 63902). No comments were received, and the 
special conditions are adopted as proposed.

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.

[[Page 20769]]

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.


0
The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Embraer S.A. Model EMB-550 airplanes.
    1. 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 issued 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 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 April 8, 2014.
John P. Piccola,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-08275 Filed 4-11-14; 8:45 am]
BILLING CODE 4910-13-P