Document ID: FAA-2013-0772-0005
Agency: faa
Document Type: Rule
Title: Special Conditions: Embraer Model EMB-550 Airplanes; Flight Envelope Protection: Normal Load Factor (g) Limiting
Posted Date: 2019-05-08T04:00Z

[Federal Register Volume 84, Number 89 (Wednesday, May 8, 2019)]
[Rules and Regulations]
[Pages 20021-20023]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-09398]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0772; Special Conditions No. 25-520A-SC]

Special Conditions: Embraer 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 amended special conditions are issued for Embraer Model 
EMB-550 airplanes. This airplane will have novel or unusual design 
features when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. This design 
feature is 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 May 8, 2019.

FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, Airplane & Flight Crew 
Interface Section, AIR-671, Transport Standards Branch, Policy and 
Innovation Division, Aircraft Certification Service, Federal Aviation 
Administration, 2200 South 216th Street, Des Moines, Washington 98198; 
telephone and fax 206-231-3158; email joe.jacobsen@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    On August 9, 2016, Embraer applied for a change to Type Certificate 
No. TC00062IB to include additional flexibility to the normal load 
factor limit on the Embraer Model EMB-550 airplane, by requesting an 
amendment to the existing Embraer Model EMB-550 Special Conditions No. 
25-520-SC as a result of harmonization efforts in the Flight Test 
Harmonization Working Group (FTHWG). The Embraer Model EMB-550 
airplane, currently approved under Type Certificate No. TC00062IB, is a 
twin-engine, transport category airplane with a maximum takeoff weight 
of 42,857 pounds. The Embraer Model EMB-550 has a maximum seating 
capacity of 12 passengers.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.101, Embraer must show that the Embraer Model EMB-550 airplane, 
as changed, continues to meet the applicable provisions of the 
regulations listed in Type Certificate No. TC00062IB or the applicable 
regulations in effect on the date of application for the change, except 
for earlier amendments as agreed upon by the FAA.
    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 Embraer 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 novel or 
unusual design feature, or should any other model already included on 
the same type certificate be modified to incorporate the same novel or 
unusual design feature, these special conditions would also apply to 
the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Embraer 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.

[[Page 20022]]

    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.  21.101.

Novel or Unusual Design Features

    The Embraer Model EMB-550 airplane will incorporate the following 
novel or unusual design features:
    The Embraer Model EMB-550 airplane flight control system design 
incorporates normal load factor limiting on a full-time basis that will 
prevent the pilot 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.

Discussion

    The normal load factor limit on the Embraer Model EMB-550 airplane 
is unique in that traditional airplanes with conventional flight 
control systems (mechanical linkages) are limited in the pitch axis 
only by the elevator surface area and deflection limit. The elevator 
control power is normally derived for adequate controllability and the 
maneuverability at the most critical longitudinal pitching moment. The 
result is that traditional airplanes have a significant portion of the 
flight envelope where maneuverability in excess of limit structural 
design values is possible. The Embraer Model EMB-550 airplane because 
of the normal load factor limit does not have this excess 
maneuverability.
    Title 14, Code of Federal Regulations (14 CFR) part 25 does not 
specify requirements for demonstrating maneuver control that impose any 
handling qualities requirements beyond the design limit structural 
loads. Nevertheless, some pilots are accustomed to the availability of 
this excess maneuver capacity in case of extreme emergency such as 
upset recoveries or collision avoidance.
    As a result of harmonization efforts with other civil aviation 
authorities through the Flight Test Harmonization Working Group (FTHWG) 
and Embraer's request to incorporate them into Special Conditions No. 
25-520-SC, the FAA is including additional flexibility in 
maneuverability limits by amending the existing Embraer Model EMB-550 
airplane Special Conditions No. 25-520-SC. This additional flexibility 
allows for reduced maneuverability limits beyond Vmo/
Mmo. The existing special conditions are otherwise 
unchanged.
    The 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.

Discussion of Comments

    The FAA issued Notice of Proposed Special Conditions No. 25-19-01-
SC for the Embraer Model EMB-550 airplane, which was published in the 
Federal Register on April 8, 2019 (84 FR 13838). The FAA received a 
response from one commenter, while generally supporting the new 
technology requested a thorough review of the system reliability and 
failure modes. The comment is already addressed in Sec.  25.1309, 
Equipment, systems, and installations.

Applicability

    As discussed above, these special conditions are applicable to the 
Embraer Model EMB-550 airplane. Should Embraer apply at a later date 
for a change to the type certificate to include another model 
incorporating the same novel or unusual design feature, these special 
conditions would apply to that model as well.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register. However, as the certification date for the Embraer 
Model EMB-550 airplane is imminent, the FAA finds that good cause 
exists to make these special conditions effective upon publication.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of airplane. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Authority Citation

    The authority citation for these special conditions is as follows:

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

The Special Conditions

0
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 Model EMB-550 airplanes.
    1. 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 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 up to Vmo/
Mmo. The positive limiting load factor may be gradually 
reduced down to 2.25g above Vmo/Mmo.
    (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) Wings level pitch up responsiveness 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) and 
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.

[[Page 20023]]

    Issued in Des Moines, Washington, on May 2, 2019.
Victor Wicklund,
Manager, Transport Standards Branch, Policy and Innovation Division, 
Aircraft Certification Service.
[FR Doc. 2019-09398 Filed 5-7-19; 8:45 am]
 BILLING CODE 4910-13-P