[Federal Register: June 7, 2002 (Volume 67, Number 110)]
[Rules and Regulations]               
[Page 39264-39265]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07jn02-8]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE174; Special Conditions No. 23-119-SC]

 
Special Conditions: Liberty Aerospace, Model XL-2 Airplane, 
Installation of Full Authority Digital Engine Control (FADEC) System 
and the Protection of the System From the Effects of High Intensity 
Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Liberty Aerospace 
Model XL-2 airplane. This airplane will have a novel or unusual design 
feature(s) associated with the installation of an engine that uses an 
electronic engine control system in place of the engine's mechanical 
system. 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.

EFFECTIVE DATE: July 8, 2002.

FOR FURTHER INFORMATION CONTACT: Ervin Dvorak, Federal Aviation 
Administration, Aircraft Certification Service, Small Airplane 
Directorate, ACE-111, 901 Locust, Room 301, Kansas City, Missouri 
64106; 816-329-4123, fax 816-329-4090.

SUPPLEMENTARY INFORMATION:

Background

    On October 26, 2000, Liberty Aerospace applied for a type 
certificate for their new Model XL-2. The Model XL-2 is powered by one 
reciprocating engine equipped with an electronic engine control system 
with full authority capability in place of the hydromechanical control 
system.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Liberty Aerospace must show 
that the Model XL-2 meets the applicable provisions of 14 CFR part 23, 
as amended by Amendments 23-1 through 23-53 thereto.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 23) do not contain adequate or 
appropriate safety standards for the Model XL-2 because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec. 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model XL-2 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 pursuant to section 611 of Public Law 92-574, the 
``Noise Control Act of 1972.''
    Special conditions, as appropriate, as defined in 11.19, are issued 
in accordance with Sec. 11.38, and become part of the type 
certification basis in accordance with Sec. 21.17(a)(2).
    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, the special conditions would also apply to the 
other model under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The Model XL-2 will incorporate the following novel or unusual 
design features:
    Liberty Aerospace, Model XL-2 airplane will use an engine that 
includes an electronic control system with full engine authority 
capability.
    Many advanced electronic systems are prone to either upsets or 
damage, or both, at energy levels lower than analog systems. The 
increasing use of high power radio frequency emitters mandates 
requirements for improved high intensity radiated fields (HIRF) 
protection for electrical and electronic equipment. Since the 
electronic engine control system used on the Liberty Aerospace, Model 
XL-2 will perform critical functions, provisions for protection from 
the effects of HIRF fields should be considered and, if necessary, 
incorporated into the airplane design data. The FAA policy contained in 
Notice 8110.71, dated April 2, 1998, establishes the HIRF energy levels 
that airplanes will be exposed to in service. The guidelines set forth 
in this Notice are the result of an Aircraft Certification Service 
review of existing policy on HIRF, in light of the ongoing work of the 
ARAC Electromagnetic Effects Harmonization Working Group (EEHWG). The 
EEHWG adopted a set of HIRF environment levels in November 1997 that 
were agreed upon by the FAA, JAA, and industry participants. As a 
result, the HIRF environments in this notice reflect the environment 
levels recommended by this working group. This notice states that a 
full authority digital engine control is an example of a system that 
should address the HIRF environments.
    Even though the control system will be certificated as part of the 
engine, the installation of an engine with an electronic control system 
requires evaluation due to the possible effects on or by other airplane 
systems (e.g., radio interference with other airplane electronic 
systems, shared engine and airplane power sources). The regulatory 
requirements in 14 CFR part 23 for evaluating the installation of 
complex systems, including electronic systems, are contained in 
Sec. 23.1309. However, when Sec. 23.1309 was developed, the use of 
electronic control systems for engines was not envisioned; therefore, 
the Sec. 23.1309 requirements were not applicable to systems 
certificated as part of the engine (reference Sec. 23.1309(f)(1)). 
Also, electronic control systems often require inputs from airplane 
data and power sources and outputs to other airplane systems (e.g., 
automated cockpit powerplant controls such as mixture setting). 
Although the parts of the system that are not certificated with the 
engine could be evaluated using the criteria of Sec. 23.1309, the 
integral nature of systems such as these makes it unfeasible to 
evaluate the airplane portion of the system without including the 
engine portion of the system. However, Sec. 23.1309(f)(1) again 
prevents complete evaluation of the installed airplane system since 
evaluation of the engine system's effects is not required.
    Therefore, special conditions are proposed for the Liberty 
Aerospace, Model XL-2 to provide HIRF protection and to evaluate the 
installation of the electronic engine control system for

[[Page 39265]]

compliance with the requirements of Sec. 23.1309(a) through (e) at 
Amendment 23-46.

Discussion of Comments

    Notice of proposed special conditions No. 23-02-01-SC for the 
Liberty Aerospace Model XL-2 airplanes was published on March 14, 2002 
(67 FR 11451). No comments were received, and the special conditions 
are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Model XL-2. Should Liberty Aerospace 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 under the provisions of Sec. 21.101.

Conclusion

    This action affects only certain novel or unusual design features 
on one model XL-2 of airplanes. It is not a rule of general 
applicability, and it affects only the applicant who applied to the FAA 
for approval of these features on the airplane.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.

Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and 
21.17; and 14 CFR 11.38 and 11.19.

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 Liberty Aerospace Model XL-2 
airplanes.
    1. High Intensity Radiated Fields (HIRF) Protection. In showing 
compliance with 14 CFR part 21 and the airworthiness requirements of 14 
CFR part 23, protection against hazards caused by exposure to HIRF 
fields for the full authority digital engine control system, which 
performs critical functions, must be considered. To prevent this 
occurrence, the electronic engine control system must be designed and 
installed to ensure that the operation and operational capabilities of 
this critical system are not adversely affected when the airplane is 
exposed to high energy radio fields.
    At this time, the FAA and other airworthiness authorities are 
unable to precisely define or control the HIRF energy level to which 
the airplane will be exposed in service; therefore, the FAA hereby 
defines two acceptable interim methods for complying with the 
requirement for protection of systems that perform critical functions.
    (1) The applicant may demonstrate that the operation and 
operational capability of the installed electrical and electronic 
systems that perform critical functions are not adversely affected when 
the aircraft is exposed to the external HIRF threat environment defined 
in the following table:

------------------------------------------------------------------------
                                                       Field strength
                                                      (volts per meter)
                     Frequency                     ---------------------
                                                       Peak     Average
------------------------------------------------------------------------
10 kHz-100 kHz....................................         50         50
100 kHz-500 kHz...................................         50         50
500 kHz-2 MHz.....................................         50         50
2 MHz-30 MHz......................................        100        100
30 MHz-70 MHz.....................................         50         50
70 MHz-100 MHz....................................         50         50
100 MHz-200 MHz...................................        100        100
200 MHz-400 MHz...................................        100        100
400 MHz-700 MHz...................................        700         50
700 MHz-1 GHz.....................................        700        100
1 GHz-2 GHz.......................................       2000        200
2 GHz-4 GHz.......................................       3000        200
4 GHz-6 GHz.......................................       3000        200
6 GHz-8 GHz.......................................       1000        200
8 GHz-12 GHz......................................       3000        300
12 GHz-18 GHz.....................................       2000        200
18 GHz-40 GHz.....................................        600       200
------------------------------------------------------------------------
The field strengths are expressed in terms of peak root-mean-square
  (rms) values.

    or,
    (2) The applicant may demonstrate by a system test and analysis 
that the electrical and electronic systems that perform critical 
functions can withstand a minimum threat of 100 volts per meter peak 
electrical strength, without the benefit of airplane structural 
shielding, in the frequency range of 10 KHz to 18 GHz. When using this 
test to show compliance with the HIRF requirements, no credit is given 
for signal attenuation due to installation. Data used for engine 
certification may be used, when appropriate, for airplane 
certification.
    2. Electronic Engine Control System. The installation of the 
electronic engine control system must comply with the requirements of 
Sec. 23.1309(a) through (e) at Amendment 23-46. The intent of this 
requirement is not to re-evaluate the inherent hardware reliability of 
the control itself, but rather determine the effects, including 
environmental effects addressed in Sec. 23.1309(e), on the airplane 
systems and engine control system when installing the control on the 
airplane. When appropriate, engine certification data may be used when 
showing compliance with this requirement.

    Issued in Kansas City, Missouri on May 29, 2002.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 02-14351 Filed 6-6-02; 8:45 am]
BILLING CODE 4910-13-P