This section of the FEDERAL REGISTER

contains regulatory documents having general

applicability and legal effect, most of which

are keyed to and codified in the Code of

Federal Regulations, which is published under

50 titles pursuant to 44 U.S.C. 1510.

The Code of Federal Regulations is sold by

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REGISTER issue of each week.

Rules and Regulations Federal Register

38075

Vol. 63, No. 135

Wednesday, July 15, 1998

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM147; Special Conditions No.

25–139–SC]

Special Conditions: Boeing Model 757–

300; High-Intensity Radiated Fields

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final special conditions.

SUMMARY: These special conditions are

issued for the Boeing Model 757–300

airplane. This airplane will utilize new

avionics/electronic systems that provide

critical data to the flightcrew. The

applicable regulations do not contain

adequate or appropriate safety standards

for the protection of these systems from

the effects of high-intensity radiated

fields. 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: August 14, 1998.

FOR FURTHER INFORMATION CONTACT: John

Dimtroff, FAA, Airplane and Flight

Crew Interface Branch, ANM–111,

Transport Airplane Directorate, Aircraft

Certification Service, 1601 Lind Avenue

SW., Renton, Washington, 98055–4056,

telephone (425) 227–2117 or facsimile

(425) 227–1320.

SUPPLEMENTARY INFORMATION:

Background

On February 21, 1996, the Boeing

Commercial Airplane Group, P. O. Box

3707, Seattle, Washington 98124–2207,

applied for an amendment to Type

Certificate No. A2NM to include the

new Model 757–300, a derivative of the

757–200. The 757–300 is a swept-wing,

conventional-tail, twin-engine, turbofanpowered transport. Each engine is

capable of delivering 43,100 pounds of

thrust. The flight controls are

unchanged beyond those changes

deemed necessary to accommodate the

stretched configuration. The airplane

has a seating capacity of up to 295, and

a maximum takeoff weight of 270,000

pounds (122,470 Kg).

Type Certification Basis

Under the provisions of Title 14 CFR

21.101, Boeing must show that the

Model 757–300 meets the applicable

provisions of the regulations

incorporated by reference in Type

Certificate No. A2NM, or the applicable

regulations in effect on the date of

application for the change to the Model

757–300. The regulations incorporated

by reference in the type certificate are

commonly referred to as the ‘‘original

type certification basis.’’ The regulations

incorporated by reference in Type

Certificate No. A2NM include 14 CFR

part 25, as amended by Amendments

25–1 through 25–45, and certain other

later amended sections of part 25 that

are not relevant to these special

conditions. Except for certain earlier

amended sections of part 25 that are not

relevant to these special conditions,

Boeing has chosen to comply with part

25 as amended by Amendments 25–1

through 25–85, the applicable

regulations in effect on the date of

application. In addition to the

applicable airworthiness regulations

and special conditions, the 757–300

must comply with the fuel vent and

exhaust emission requirements of part

34, effective September 10, 1990, plus

any amendments in effect at the time of

certification; and the noise certification

requirements of part 36, effective

December 1, 1969, as amended by

Amendment 36–1 through the

amendment in effect at the time of

certification. These special conditions

form an additional part of the type

certification basis.

If the Administrator finds that the

applicable airworthiness regulations

(i.e., part 25, as amended) do not

contain adequate or appropriate safety

standards for the 757–300 because of a

novel or unusual design feature, special

conditions are prescribed under the

provisions of § 21.16 to establish a level

of safety equivalent to that established

in the regulations.

Special conditions, as appropriate, are

issued in accordance with § 11.49 of the

FAR after public notice, as required by

§§ 11.28 and 11.29(b), and become part

of the type certification basis in

accordance with § 21.101(b)(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, or should any other

model already included on the same

type certificate be modified to

incorporate 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

The 757–300 airplane avionics

enhancement utilizes electronic systems

that perform critical functions,

including the following airframe Line

Replaceable Units (LRU): Multi-Mode

Receiver (MMR), Flight Control

Computer (FCC), Yaw Damper Stabilizer

Trim Module (YSM), Air Data Inertial

Reference System (ADIRS), and the

Allied Signal Radio Altimeter (RA).

These systems may be vulnerable to

high-intensity radiated fields (HIRF)

external to the airplane.

Discussion

There is no specific regulation that

addresses protection requirements for

electrical and electronic systems from

HIRF. Increased power levels from

ground based radio transmitters, and the

growing use of sensitive electrical and

electronic systems to command and

control airplanes, have made it

necessary to provide adequate

protection.

To ensure that a level of safety is

achieved equivalent to that intended by

the regulations incorporated by

reference, special conditions are needed

for the 757–300, which require that new

technology electrical and electronic

systems, such as the MMR, FCC, YSM,

ADIRS, and RA, be designed and

installed to preclude component

damage and interruption of function

due to both the direct and indirect

effects of HIRF.

High-Intensity Radiated Fields

With the trend toward increased

power levels from ground based

transmitters, plus the advent of space

and satellite communications, coupled

with electronic command and control of
38076 Federal Register / Vol. 63, No. 135 /Wednesday, July 15, 1998 /Rules and Regulations

the airplane, the immunity of critical

digital avionics systems to HIRF must be

established.

It is not possible to precisely define

the HIRF to which the airplane will be

exposed in service. There is also

uncertainty concerning the effectiveness

of airframe shielding for HIRF.

Furthermore, coupling of

electromagnetic energy to cockpitinstalled equipment through the cockpit

window apertures is undefined. Based

on surveys and analysis of existing HIRF

emitters, an adequate level of protection

exists when compliance with the HIRF

protection special condition is shown

with either paragraphs 1 or 2 below:

1. A minimum threat of 100 volts per

meter peak electric field strength from

10 KHz to 18 GHz.

a. The threat must be applied to the

system elements and their associated

wiring harnesses without the benefit of

airframe shielding.

b. Demonstration of this level of

protection is established through system

tests and analysis.

2. A threat external to the airframe of

the following field strengths for the

frequency ranges indicated.

Frequency

Field strength (volts per meter)

US UK/European Consolidated

Peak Avg. Peak Avg. Peak Avg.

10 kHz–100 kHz ............................................................... 30 30 50 50 50 50

100 kHz–500 kHz ............................................................. 40 30 60 60 60 60

500 kHz–2 MHz ................................................................ 30 30 70 70 70 70

2 MHz–30 MHz ................................................................. 190 190 200 200 200 200

30 MHz–70 MHz ............................................................... 20 20 30 30 30 30

70 MHz–100 MHz ............................................................. 20 20 30 30 30 30

100 MHz–200 MHz ........................................................... 30 30 150 30 150 30

200 MHz–400 MHz ........................................................... 30 30 70 70 70 70

400 MHz–700 MHz ........................................................... 80 80 700 40 700 80

700 MHz–1 GHz ............................................................... 690 240 1700 80 1700 240

1 GHz–2 GHz ................................................................... 970 70 5000 360 5000 360

2 GHz–4 GHz ................................................................... 1570 350 4500 360 4500 360

4 GHz–6 GHz ................................................................... 7200 300 5200 300 7200 300

6 GHz–8 GHz ................................................................... 130 80 2000 330 2000 330

8 GHz–12 GHz ................................................................. 2100 80 3500 270 3500 270

12 GHz–18 GHz ............................................................... 500 330 3500 180 3500 330

18 GHz–40 GHz ............................................................... 780 20 NA NA 780 20

The field strengths are expressed in terms of peak root-mean-square (rms) values.

The threat levels identified above

differ from those used in previous

special conditions and are the result of

an FAA review of existing studies on

the subject of HIRF, in light of the

ongoing work of the Electromagnetic

Effects Harmonization Working Group

of the Aviation Rulemaking Advisory

Committee. In general, these standards

are less critical than the threat level that

was previously used as the basis for

earlier special conditions

Discussion of Comments

Notice of Proposed Special

Conditions No. 25–98–02–SC for the

757–300 was published in the Federal

Register on March 25, 1998 (63 FR

14381). Three commenters responded.

The first commenter, representing the

interests of airline pilots, concurs with

the special conditions as proposed.

The second commenter, the United

Kingdom Civil Aviation Authority

(CAA), states that harmonized HIRF

requirements and associated guidance

material arising from FAA/Joint

Aviation Authorities (JAA) participation

in a working group of the Aviation

Rulemaking Advisory Committee

(ARAC) are well established and known

to the FAA and should be applied by

the FAA where special conditions of

this nature are required. The commenter

also states that the JAA has applied the

harmonized requirements and means of

compliance, and as the FAA may be

faced with finding compliance on behalf

of the JAA, it may be inappropriate for

the FAA to apply any special condition

or means of compliance that is not in

accordance with the harmonized

standards.

The FAA concurs with this

commenter; however, at the time of

application for certification of the 757–

300, the requirements depicted in the

certification program were not fully

harmonized. The HIRF requirements in

place at the time were as depicted in the

proposed special condition. Future

airplane certification programs will

include the fully harmonized

requirements. Also, Boeing can elect to

use the newer, harmonized requirement

table if they so choose.

The applicant, Boeing Commercial

Airplane Group, also provided

comments on the proposed special

conditions. Boeing does not believe a

HIRF special condition should be

applied to existing production airplane

models. The FAA does not agree.

Section 21.101 of 14 CFR part 21 states

that special conditions can be applied to

both new and substantially complete

redesigns of a component, equipment

installation, or system installation.

Upgrades of existing production

airplanes, if the upgrade incorporates

new or substantially complete redesigns

of a component, equipment installation,

or system installation, do fall within the

scope of § 21.101.

Boeing also states that applying the

HIRF special conditions would deter

them from upgrading existing airplane

models. The FAA has consistently

applied the requirements in the HIRF

special condition to avionics upgrades

of existing production model airplanes.

Many of these upgrades have been in

the form of supplemental type

certifications on Boeing airplanes and

were designed and installed by

applicants other than Boeing. The

special conditions have not deterred

other applicants from upgrading

existing Boeing airplanes. Also, Boeing

already applies the requirements within

the HIRF special conditions to existing

production model airplanes. When

Boeing certified the Model 777–200 and

the Model 777–300, components,

equipment installations, or system

installations from the Model 777–200,

which were new or substantially

redesigned, were shown to comply with

the requirements of the HIRF special

condition. When the engines on the

Model 767 were upgraded to include

Full Authority Digital Engine Controls
Federal Register / Vol. 63, No. 135 /Wednesday, July 15, 1998 /Rules and Regulations 38077

(FADECs), the FADECs were shown to

comply with the HIRF special

conditions. The FAA HIRF requirements

have been consistent, and Boeing has

been aware of and complied with these

requirements for several years.

Boeing further states that the HIRF

special condition would effectively

deter them from upgrading electronic

equipment that incorporates safety and

reliability enhancing features. The FAA

requirements in the HIRF special

condition reflect the need to address a

known environmental hazard,

recognized by the technical and

regulatory community worldwide.

Protection against this known

environmental hazard is required by

FAA for all systems performing

functions whose failure would

contribute to or cause a catastrophic

failure condition that would prevent the

continued safe flight and landing of the

airplane. This policy applies, regardless

of whether the new or significantly

changed component, equipment, or

system is intended to improve an

unrelated safety or reliability issue.

Improving one aspect of safety or

reliability should not degrade another

aspect of safety.

The FAA has consistently applied the

requirements in the HIRF special

conditions to certification programs for

over 12 years, regardless of whether the

certification was based on a new

airplane type, or a change to an existing

airplane. Changing this policy for one

model of Boeing airplanes would not be

consistent with the FAA policy over the

last 12 years. Therefore, special

conditions for the 757–300 are adopted

as proposed in Notice 25–98–02–SC.

Applicability

As discussed above, these special

conditions are applicable initially to the

Model 757–300 airplane. Should Boeing

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

§ 21.101(a)(1).

Conclusion

This action affects certain design

features only on the Model 757–300. It

is not a rule of general applicability and

affects only the manufacturer who

applied to the FAA for approval of these

features on this model.

List of Subjects in 14 CFR Part 25

Aircraft, Aviation safety, Reporting

and recordkeeping requirements.

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 Boeing Model

757–300 series airplanes.

1. Protection from Unwanted Effects

of High-Intensity Radiated Fields

(HIRF). Each electrical and electronic

system that performs critical functions

must be designed and installed to

ensure that the operation and

operational capability of these systems

to perform critical functions are not

adversely affected when the airplane is

exposed to high-intensity radiated

fields.

2. For the purpose of this special

condition, the following definition

applies:

Critical Functions. Functions whose

failure would contribute to or cause a

failure condition that would prevent the

continued safe flight and landing of the

airplane.

Issued in Renton, Washington, on July 7,

1998.

John J. Hickey,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 98–18857 Filed 7–14–98; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98–NM–41–AD; Amendment

39–10651; AD 98–15–01]

RIN 2120–AA64

Airworthiness Directives; Empresa

Brasileira de Aeronautica S.A.

(EMBRAER) Model EMB–145 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain EMBRAER Model

EMB–145 series airplanes, that requires

a one-time inspection to detect bulging

or cracking of the pitot 1 and pitot 2

drain tubes in the forward electronic

compartment; and cleaning the tubes or

replacing drain tubes with new tubes, if

necessary. This amendment also

requires modification of the pitot/static

system. 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 detect and correct bulging

and cracking of the pitot 1 and pitot 2

drain tubes in the forward electronic

compartment caused by cycles of water

freezing and expanding inside the tubes,

which could result in erroneous

airspeed indications to the flight crew

and reduced operational safety in all

phases of flight.

DATES: Effective August 19, 1998.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of August 19,

1998.

ADDRESSES: The service information

referenced in this AD may be obtained

from Empresa Brasileira de Aeronautica

S.A. (EMBRAER), P.O. Box 343—CEP

12.225, Sao Jose dos Campos—SP,

Brazil. This information may be

examined at the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, Rules Docket,

1601 Lind Avenue, SW., Renton,

Washington; or at the FAA, Small

Airplane Directorate, Atlanta Aircraft

Certification Office, One Crown Center,

1895 Phoenix Boulevard, suite 450,

Atlanta, Georgia; or at the Office of the

Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Neil

Berryman, Aerospace Engineer, Systems

and Flight Test Branch, ACE–116A,

FAA, Small Airplane Directorate,

Atlanta Aircraft Certification Office,

One Crown Center, 1895 Phoenix

Boulevard, suite 450, Atlanta, Georgia

30337–2748; telephone (770) 703–6066;

fax (770) 703–6097.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to

include an airworthiness directive (AD)

that is applicable to certain EMBRAER

Model EMB–145 series airplanes was

published in the Federal Register on

April 8, 1998 (63 FR 17130). That action

proposed to require a one-time

inspection to detect bulging or cracking

of the pitot 1 and pitot 2 drain tubes in

the forward electronic compartment;

and cleaning the tubes or replacing

drain tubes with new tubes, if

necessary. That action also proposed

modification of the pitot/static system.

Comments

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

single comment received.