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[Federal Register Volume 69, Number 223 (Friday, November 19, 2004)]
[Rules and Regulations]
[Pages 67636-67638]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-25698]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE213; Special Conditions No. 23-152-SC]

Special Conditions: Thielert Aircraft Engines; Cessna Model 172 
K, L, M, N, P, R, and S Series Airplanes; Installation of Thielert TAE-
125-01 Aircraft Diesel Engine for 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; request for comments.

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SUMMARY: These special conditions are issued to Thielert Aircraft 
Engines, GmbH, Lichtenstein, Germany for a supplemental type 
certificate for the Cessna Model 172 series airplanes. The supplemental 
type certificate for these airplanes will have a novel or unusual 
design feature associated with the installation of an aircraft diesel 
engine that uses an electronic engine control system instead of a 
mechanical control 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.

DATES: The effective date of these special conditions is: November 1, 
2004. Comments must be received on or before December 20, 2004.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration (FAA), Regional Counsel, ACE-7, 
Attention: Rules Docket, Docket No. CE213, 901 Locust, Room 506, Kansas 
City, Missouri 64106, or delivered in duplicate to the Regional Counsel 
at the above address. Comments must be marked: Docket No. CE213. 
Comments may be inspected in the Rules Docket weekdays, except Federal 
holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Pete Rouse, Federal Aviation 
Administration, Aircraft Certification Service, Small Airplane 
Directorate, ACE-111, 901 Locust, Room 301, Kansas City, Missouri 
64106; telephone: (816) 329-4135, fax: (816) 329-4090.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are impracticable because 
these procedures would significantly delay issuance of the design 
approval and thus delivery of the affected aircraft. In addition, the 
substance of these special conditions has been subject to the public 
comment process in several prior instances with no substantive comments 
received. The FAA, therefore, finds that good cause exists for making 
these special conditions effective upon issuance.

Comments Invited

    Interested persons are invited to submit such written data, views, 
or arguments as they may desire. Communications should identify the 
regulatory docket or special condition number and be submitted in 
duplicate to the address specified above. All communications received 
on or before the closing date for comments will be considered by the 
Administrator. The special conditions may be changed in light of the 
comments received. All comments received will be available in the Rules 
Docket for examination by interested persons, both before and after the 
closing date for comments. A report summarizing each substantive public 
contact with FAA personnel concerning this rulemaking will be filed in 
the docket. Commenters wishing the FAA to acknowledge receipt of their 
comments submitted in response to this notice must include a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. CE213.'' The postcard will be date stamped and 
returned to the commenter.

Background

    On February 11, 2002, Thielert Aircraft Engines applied for a 
supplemental type certificate for the Cessna Model 172 series 
airplanes. The supplemental type certificate will allow Thielert 
Aircraft Engines to install a Thielert Aircraft engine (TAE 125-01 
aircraft diesel engine (ADE)) that is equipped with an electronic 
engine control system with full authority capability in these 
airplanes.

Type Certification Basis

    Under the provisions of 14 CFR, part 21, Sec.  21.101, Thielert 
Aircraft Engines must show that the Cessna Model 172 meets the 
applicable provisions of the original certification basis of the Cessna 
Model 172, as listed on Type Certificate No. 3A12, issued on November 
4, 1955; exemptions, if any; and the special conditions adopted by this 
rulemaking action. The Cessna Model 172 was originally certified under 
part 3 of the Civil Air Regulations.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., CAR 3; 14 CFR, part 23) do not contain adequate or 
appropriate safety standards for the Cessna 172 because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec.  21.16.
    Special conditions, as appropriate, as defined in Sec.  11.19, are 
issued in accordance with Sec.  11.38, and become part of the 
certification basis for the supplemental type certification basis in 
accordance with Sec.  21.101. Special conditions are initially 
applicable to the model for which they are issued. Should the applicant 
apply for a supplemental type certificate to modify any other models 
that are listed on the same type certificate to incorporate the same 
novel or unusual design features, the special conditions would also 
apply under the provisions of Sec.  21.101.

Novel or Unusual Design Features

    The Thielert Aircraft Engines modified Cessna Model 172 will 
incorporate a novel or unusual design feature, an engine that includes 
an electronic control system with full authority digital engine control 
(FADEC) 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 Thielert

[[Page 67637]]

Aircraft Engines modified Cessna Model 172 will perform critical 
functions, provisions for protection from the effects of HIRF 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 Aviation Rulemaking Advisory Committee 
(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, the Joint Aviation Authorities (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 FADEC 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 Thielert 
Aircraft Engines modified Cessna Model 172 airplane to provide HIRF 
protection and to evaluate the installation of the electronic engine 
control system for compliance with the requirements of Sec.  23.1309(a) 
through (e) at Amendment 23-49.

Applicability

    As discussed above, these special conditions are applicable to the 
Thielert Aircraft Engines modified Cessna Model 172. Should Thielert 
Aircraft Engines apply at a later date for a supplemental type 
certificate to modify any other model included on the same type 
certificate as the Thielert Aircraft Engines modified Cessna Model 172 
to incorporate the same novel or unusual design features, 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, the Cessna Model 172 K, L, M, N, P, R, and S series 
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.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register. However the FAA finds that good cause exists to make 
these special conditions effective upon issuance.

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 
21.101; 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 supplemental type certification basis for Thielert Aircraft Engines 
modified Cessna Model 172 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)
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                      Frequency                         Peak     Average
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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-2GHz..........................................      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 23-49. 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

[[Page 67638]]

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 November 1, 2004.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-25698 Filed 11-18-04; 8:45 am]
BILLING CODE 4910-13-P
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