Federal Register / Vol. 65, No. 229 / Tuesday, November 28, 2000 / Rules and Regulations 70773

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 29

[Docket No. SW007; Special Condition No.

29–007–SC]

Special Conditions: Eurocopter France

Model EC–155 Helicopters, HighIntensity Radiated Fields

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Final special condition; request

for comments.

SUMMARY: This special condition is

issued for Eurocopter France

(Eurocopter) Model EC–155 helicopters.

These helicopters will have novel or

unusual design features associated with

the installation of electronic systems

that perform critical functions. The

applicable airworthiness regulations do

not contain adequate or appropriate

safety standards to protect systems that

perform critical control functions or

provide critical displays from the effects

of high-intensity radiated fields (HIRF).

This special condition contains the

additional safety standards that the

Administrator considers necessary to

ensure that critical functions of systems

will be maintained when exposed to

HIRF.

DATES: The effective date of this special

condition is October 31, 2000.

Comments must be received on or

before January 12, 2001.

ADDRESSES: Comments on this special

condition may be mailed in duplicate

to: Federal Aviation Administration,

Office of the Regional Counsel,

Attention: Rules Docket No. SW007,

Fort Worth, Texas 76193–0007, or

delivered in duplicate to the Office of

the Regional Counsel at 2601 Meacham

Blvd., Fort Worth, Texas 76137.

Comments must be marked: Rules

Docket No. SW007. Comments may be

inspected in the Rules Docket

weekdays, except Federal holidays,

between 8:30 a.m. and 4:00 p.m.

FOR FURTHER INFORMATION CONTACT:

Jorge Castillo, FAA, Rotorcraft

Directorate, Rotorcraft Standards, Fort

Worth, Texas 76193–0110; telephone

(817) 222–5127, fax (817) 222–5961.

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 approval design and

thus delivery of the affected aircraft. In

addition, notice and opportunity for

prior public comment are unnecessary

since the substance of this special

condition 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 this special

condition 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. The special condition may

be changed in light of the comments

received. All comments received will be

available in the Rules Docket for

examination by interested persons. 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

special condition must include a selfaddressed, stamped postcard on which

the following statement is made:

‘‘Comments to Rules Docket No.

SW007.’’ The postcard will be date

stamped and returned to the

commenter.

Background

On September 1, 1998, Eurocopter

submitted an application for Type

Validation of Model EC–155 Transport

Category helicopters through the

Direction Generale de l’Aviation Civile

(DGAC), which is the airworthiness

authority of France, and the FAA

Brussels Aircraft Certification Office

(ACO). Model EC–155 helicopters are a

derivative of Model AS365N3

helicopters that achieved FAA Type

Certification on November 8, 1998. The

main design differences between Model

EC–155 and Model AS365N3

helicopters include the following: a

gross weight increase from 4250 kg to

4800 kg; enlarged fuselage structure; a

new 5-blade speriflex main rotor and

composite fenestron blades; and a new

avionics instrumentation package that

includes a 3-axis digital Automatic

Flight Control System (AFCS) and

electronic displays.

Type Certification Basis

Under the provisions of 14 CFR 21.17,

Eurocopter must show that Model EC–

155 helicopters meet the applicable

provisions of the regulations as listed

below:

—14 CFR 21.29.

—14 CFR part 29, Amendment 29–1

through Amendment 29–40 with the

following exceptions:

—Excluding Amendment 29–38.

—Excluding 14 CFR 29.952,

introduced at Amendment 29–35.

—Excluding 14 CFR 29.562,

introduced at Amendment 29–29.

—Excluding 14 CFR 29.631,

introduced at Amendment 29–40.

—Section 29.561(a), (b), and (d) at

Amendment 29–1.

—Section 29.561(c) at Amendment

29–29.

—Section 29.571 at Amendment 29–

20.

—Section 29.785 at Amendment 29–

24.

—Section’s 29.963, 29.973, and

29.975 at Amendment 29–26.

—Section 29.1305(a)(4)(i) at

Amendment 29–16.

—14 CFR part 36, Appendix H

through the latest amendment in effect

at the time that the noise tests are

conducted.

—Any Special conditions,

Exemptions, and Equivalent Safety

Findings deemed necessary.

In addition, the certification basis

includes certain special conditions and

equivalent safety findings that are not

relevant to this special condition.

If the Administrator finds that the

applicable airworthiness regulations do

not contain adequate or appropriate

safety standards for these helicopters

because of a novel or unusual design

feature, special conditions are

prescribed under the provisions of

§ 21.16.

In addition to the applicable

airworthiness regulations and special

conditions, Eurocopter Model EC–155

helicopters must comply with 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, are

issued in accordance with § 11.49, as

required by §§ 11.28 and 11.29(b), and

become part of the type certification

basis in accordance with § 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 § 21.101(a)(1).

Novel or Unusual Design Features

Eurocopter Model EC–155 helicopters

will incorporate the following novel or

unusual design features: electrical,

70774 Federal Register / Vol. 65, No. 229 / Tuesday, November 28, 2000 / Rules and Regulations

electronic, or a combination of electrical

electronic (electrical/electronic) systems

that will perform critical control

functions or display critical

information, such as electronic flight

instruments that display critical

information required for the continued

safe flight and landing of the helicopter

during operation in Instrument

Meteorological Conditions (IMC); and

Full Authority Digital Engine Control

(FADEC) that will perform engine

control functions that are critical to the

continued safe flight and landing of the

helicopter during Visual Flight Rules

(VFR) and Instrument Flight Rules (IFR)

operations.

Discussion

Eurocopter Model EC–155

helicopters, at the time of application,

were identified as incorporating one and

possibly more electrical/electronic

systems, such as electronic flight

instruments and FADEC. After the

design is finalized, Eurocopter will

provide the FAA with a preliminary

hazard analysis that will identify any

other critical functions required for safe

flight and landing that are performed by

the electrical/electronic systems.

Recent advances in technology have

given rise to the application in aircraft

designs of advanced electrical/

electronic systems that perform critical

control functions or provide critical

displays. These advanced systems

respond to the transient effects of

induced electrical current and voltage

caused by HIRF incident on the external

surface of the helicopter. These induced

transient currents and voltages can

degrade the performance of the

electrical/electronic systems by

damaging the components or by

upsetting the systems’ functions.

Furthermore, the electromagnetic

environment has undergone a

transformation not envisioned by the

current application of § 29.1309(a).

Higher energy levels radiate from

operational transmitters currently used

for radar, radio, and television. Also, the

number of transmitters has increased

significantly.

Existing aircraft certification

requirements are inappropriate in view

of these technological advances. In

addition, the FAA has received reports

of some significant safety incidents and

accidents involving military aircraft

equipped with advanced electrical/

electronic systems when they were

exposed to electromagnetic radiation.

The combined effects of the

technological advances in helicopter

design and the changing environment

have resulted in an increased level of

vulnerability of the electrical/electronic

systems required for the continued safe

flight and landing of the helicopter.

Effective measures to protect these

helicopters against the adverse effects of

exposure to HIRF will be provided by

the design and installation of these

systems. The following primary factors

contributed to the current conditions:

(1) Increased use of sensitive electronics

that perform critical functions; (2)

reduced electromagnetic shielding

afforded helicopter systems by

advanced technology airframe materials;

(3) adverse service experience of

military aircraft using these

technologies; and (4) an increase in the

number and power of radio frequency

emitters and the expected increase in

the future.

The FAA recognizes the need for

aircraft certification standards to keep

pace with the developments in

technology and environment and, in

1986, initiated a high priority program

to: (1) Determine and define

electromagnetic energy levels; (2)

develop and describe guidance material

for design, test, and analysis; and (3)

prescribe and promulgate regulatory

standards.

The FAA participated with industry

and airworthiness authorities of other

countries to develop internationally

recognized standards for certification.

The FAA and airworthiness

authorities of other countries have

identified two levels of the HIRF

environment that a helicopter could be

exposed to, one environment for VFR

operations and a different environment

for IFR operations. While the HIRF

rulemaking requirements are being

finalized, the FAA is adopting a special

condition for the certification of aircraft

that employ electrical/electronic

systems that perform critical control

functions or provide critical displays.

The accepted maximum energy levels

that civilian helicopter system

installations must withstand for safe

operation are based on surveys and

analysis of existing radio frequency

emitters. This special condition will

require the helicopters’ electrical/

electronic systems and associated

wiring to be protected from these energy

levels. These external threat levels are

believed to represent the exposure for a

helicopter operating under VFR or IFR.

Compliance with HIRF requirements

will be demonstrated by tests, analysis,

models, similarity with existing

systems, or a combination of these

methods. Service experience alone will

not be acceptable since such experience

in normal flight operations may not

include an exposure to HIRF. Reliance

on a system with similar design features

for redundancy, as a means of

protection against the effects of external

HIRF, is generally insufficient because

all elements of a redundant system are

likely to be concurrently exposed to the

radiated fields.

This special condition will require the

aircraft-installed systems that perform

critical control functions or provide

critical displays to meet certain

standards based on either a defined

HIRF environment or a fixed value

using laboratory tests. Control system

failures and malfunctions can more

directly and abruptly contribute to a

catastrophic event than display system

failures and malfunctions. Therefore, it

is considered appropriate to require

more rigorous HIRF verification

methods for critical control systems

than for critical display systems.

The applicant may demonstrate that

the operation and operational

capabilities of the installed electrical/

electronic systems that perform critical

functions are not adversely affected

when the aircraft is exposed to the

defined HIRF test environment. The

FAA has determined that the test

environment defined in Table 1 is

acceptable for critical control functions

in helicopters. The test environment

defined in Table 2 is acceptable for

critical display systems in helicopters.

The applicant may also demonstrate

by a laboratory test that the electrical/

electronic systems that perform critical

control functions or provide critical

displays can withstand a peak

electromagnetic field strength in a

frequency range of 10 kHz to 18 GHz. If

a laboratory test is used to show

compliance with the defined HIRF

environment, no credit will be given for

signal attenuation due to installation. A

level of 100 volts per meter (v/m) is

appropriate for critical display systems.

A level of 200 v/m is appropriate for

critical control functions. Laboratory

test levels are defined according to

RTCA/DO–160D Section 20 Category W

(100 v/m and 150 mA) and Category Y

(200 v/m and 300 mA). As stated in DO–

160D Section 20, the test levels are

defined as the peak of the root means

squared (rms) envelope. As a minimum,

the modulations required for RTCA/

DO–160D Section 20 Categories W and

Y will be used. Other modulations

should be selected as the signal most

likely to disrupt the operation of the

system under test, based on its design

characteristics. For example, flight

control systems may be susceptible to 3

Hz square wave modulation while the

video signals for electronic display

systems may be susceptible to 400 Hz

sinusoidal modulation. If the worst-case

modulation is unknown or cannot be

determined, default modulations may be

Federal Register / Vol. 65, No. 229 / Tuesday, November 28, 2000 / Rules and Regulations 70775

used. Suggested default values are a 1

kHz sine wave with 80 percent depth of

modulation in the frequency range from

10 kHz to 400 MHz and 1 kHz square

wave with greater than 90 percent depth

of modulation from 400 MHz to 18 GHz.

For frequencies where the unmodulated

signal would cause deviations from

normal operation, several different

modulating signals with various

waveforms and frequencies should be

applied.

Applicants must perform a

preliminary hazard analysis to identify

electrical/electronic systems that

perform critical functions. The term

‘‘critical’’ means those functions whose

failure would contribute to or cause an

unsafe condition that would prevent the

continued safe flight and landing of the

helicopters. The systems identified by

the hazard analysis as performing

critical functions are required to have

HIRF protection. A system may perform

both critical and non-critical functions.

Primary electronic flight display

systems and their associated

components perform critical functions

such as attitude, altitude, and airspeed

indications. HIRF requirements would

apply only to the systems that perform

critical functions, including control and

display.

Acceptable system performance

would be attained by demonstrating that

the critical function components of the

system under consideration continue to

perform their intended function during

and after exposure to required

electromagnetic fields. Deviations from

system specifications may be acceptable

but must be independently assessed by

the FAA on a case-by-case basis.

TABLE 1.—VFR ROTORCRAFT

Field strength volts/meter

Frequency Peak Average

10 kHz—100 kHz ........... 150 150

100 kHz—500 kHz ......... 180 150

500 kHz—2 MHz ............ 140 140

2 MHz—30 MHz ............. 610 610

30 MHz—70 MHz ........... 80 80

70 MHz—100 MHz ......... 150 150

100 MHz—200 MHz ....... 300 140

200 MHz—400 MHz ....... 160 140

400 MHz—700 MHz ....... 540 400

700 MHz—1 GHz ........... 2400 400

1 GHz—2 GHz ............... 7000 250

2 GHz—4 GHz ............... 8600 840

4 GHz—6 GHz ............... 13700 1270

6 GHz—8 GHz ............... 1800 800

8 GHz—12 GHz ............. 8000 500

12 GHz—18 GHz ........... 3300 560

18 GHz—40 GHz ........... 1800 700

TABLE 2.—VFR ROTORCRAFT

Field strength volts/meter

Frequency Peak Average

10 kHz—100 kHz ........... 50 50

100 kHz—500 kHz ......... 60 60

500 kHz—2 MHz ............ 70 70

2 MHz—30 MHz ............. 200 200

30 MHz—70 MHz ........... 30 30

70 MHz—100 MHz ......... 30 30

100 MHz—200 MHz ....... 150 30

200 MHz—400 MHz ....... 70 70

400 MHz—700 MHz ....... 700 80

700 MHz—1 GHz ........... 1700 240

1 GHz—2 GHz ............... 5000 360

2 GHz—4 GHz ............... 4500 360

4 GHz—6 GHz ............... 7200 300

6 GHz—8 GHz ............... 2000 330

8 GHz—12 GHz ............. 3500 270

12 GHz—18 GHz ........... 3500 330

18 GHz—40 GHz ........... 780 20

Applicability

As previously discussed, this special

condition is applicable to Eurocopter

Model EC–155 helicopters. Should

Eurocopter 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 condition would apply to that

model as well under the provisions of

§ 21.101(a)(1).

Conclusion

This action affects only certain novel

or unusual design features on one model

series of helicopters. It is not a rule of

general applicability and affects only

the applicant who applied to the FAA

for approval of these features on the

helicopter.

The substance of this special

condition has been subjected to the

notice and comment period in several

prior instances and has been derived

without substantive change from those

previously issued. It is unlikely that

prior public comment would result in a

significant change from the substance

contained herein. For this reason and

because a delay would significantly

affect the certification of the helicopter,

which is imminent, the FAA has

determined that prior public notice and

comment are unnecessary and

impracticable, and good cause exists for

adopting this special condition upon

issuance. The FAA is requesting

comments to allow interested persons to

submit views that may not have been

submitted in response to the prior

opportunities for comment described

above.

List of Subjects in 14 CFR Part 29

Aircraft, Air transportation, Aviation

safety, Rotorcraft, Safety.

Authority: The authority citation for these

special conditions is as follows: 42 U.S.C.

7572; 49 U.S.C. 106(g), 40105, 40113, 44701–

44702, 44704, 44709, 44711, 44713, 44715,

45303.

The Special Condition

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the following special

condition is issued as part of the type

certification basis for Eurocopter Model

EC–155 helicopters.

Protection for Electrical and Electronic

Systems From High-Intensity Radiated

Fields

Each system that performs critical

functions must be designed and

installed to ensure that the operation

and operational capabilities of these

critical functions are not adversely

affected when the helicopter is exposed

to high-intensity radiated fields external

to the helicopter.

Issued in Fort Worth, Texas, on October 31,

2000.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate,

Aircraft Certification Service.

[FR Doc. 00–30303 Filed 11–27–00; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–NM–273–AD; Amendment

39–11999; AD 2000–23–26]

RIN 2120–AA64

Airworthiness Directives; Aerospatiale

Model ATR72 Series Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to all Aerospatiale Model

ATR72 series airplanes, that requires a

revision to the Airworthiness

Limitations Section of the Instructions

for Continued Airworthiness to

incorporate inspections to detect fatigue

cracking in certain structure, inspection

intervals, and life limits for certain

components. This amendment is

prompted by issuance of mandatory

continuing airworthiness information by

a foreign civil airworthiness authority.

The actions specified by this AD are

intended to ensure that fatigue cracking

of certain structural elements is detected

and corrected; such fatigue cracking