Federal Register / Vol. 62, No. 179 / Tuesday, September 16, 1997 / Proposed Rules 48553

• Immediately request priority handling

from Air Traffic Control to facilitate a route

or an altitude change to exit the severe icing

conditions in order to avoid extended

exposure to flight conditions more severe

than those for which the airplane has been

certificated.

• Avoid abrupt and excessive

maneuvering that may exacerbate control

difficulties.

• Do not engage the autopilot.

• If the autopilot is engaged, hold the

control wheel firmly and disengage the

autopilot.

• If an unusual roll response or

uncommanded roll control movement is

observed, reduce the angle-of-attack.

• Do not extend flaps when holding in

icing conditions. Operation with flaps

extended can result in a reduced wing angleof-attack, with the possibility of ice forming

on the lower surface further aft on the wing

than normal, possibly aft of the protected

area.

• If the flaps are extended, do not retract

them until the airframe is clear of ice.

• Report these weather conditions to ‘‘Air

Traffic Control.’’

(b) Incorporating the AFM revisions, as

required by this AD, may be performed by

the owner/operator holding at least a private

pilot certificate as authorized by section 43.7

of the Federal Aviation Regulations (14 CFR

43.7), and must be entered into the aircraft

records showing compliance with this AD in

accordance with section 43.11 of the Federal

Aviation Regulations (14 CFR 43.11).

(c) Special flight permits may be issued in

accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to

a location where the requirements of this AD

can be accomplished.

(d) An alternative method of compliance or

adjustment of the compliance time that

provides an acceptable level of safety may be

used if approved by the Manager, Small

Airplane Directorate, FAA, 1201 Walnut,

suite 900, Kansas City, Missouri 64106. The

request shall be forwarded through an

appropriate FAA Maintenance Inspector,

who may add comments and then send it to

the Manager, Small Airplane Directorate.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Small Airplane

Directorate.

(e) All persons affected by this directive

may examine information related to this AD

at the FAA, Central Region, Office of the

Assistant Chief Counsel, Room 1558, 601 E.

12th Street, Kansas City, Missouri 64106.

Issued in Kansas City, Missouri, on

September 9, 1997.

James E. Jackson,

Acting Manager, Small Airplane Directorate,

Aircraft Certification Service.

[FR Doc. 97–24495 Filed 9–15–97; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–NM–173–AD]

RIN 2120–AA64

Airworthiness Directives; McDonnell

Douglas Model DC–3 and DC–4 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to all

McDonnell Douglas Model DC–3 and

DC–4 series airplanes. This proposal

would require revising the Airplane

Flight Manual (AFM) to specify

procedures that would prohibit flight in

severe icing conditions (as determined

by certain visual cues), limit or prohibit

the use of various flight control devices

while in sever icing conditions, and

provide the flight crew with recognition

cues for, and procedures for exiting

from, severe icing conditions. This

proposal is prompted by results of a

review of the requirements for

certification of the airplane in icing

conditions, new information on the

icing environment, and icing data

provided currently to the flight crews.

The actions specified by the proposed

AD are intended to minimize the

potential hazards associated with

operating the airplane in severe icing

conditions by providing more clearly

defined procedures and limitations

associated with such conditions.

DATES: Comments must be received by

October 14, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 97–NM–

173–AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055–4056.

Comments may be inspected at this

location between 9:00 a.m. and 3:00

p.m., Monday through Friday, except

Federal holidays.

This information may be examined at

the FAA, Transport Airplane

Directorate, 601 Lind Avenue, SW.,

Renton, Washington; or at the FAA,

Transport Airplane Directorate, Los

Angeles Aircraft Certification Office,

3960 Paramount Boulevard, Lakewood,

California.

FOR FURTHER INFORMATION CONTACT:

Albert Lam, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130L, FAA, Transport Airplane

Directorate, Los Angeles Aircraft

Certification Office, 3960 Paramount

Boulevard, Lakewood, California

90712–4137; telephone (562) 627–5346

fax (562) 627–5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

participate in the making of the

proposed rule by submitting such

written data, views, or arguments as

they may desire. Communications shall

identify the Rules Docket number and

be submitted in triplicate to the address

specified above. All communications

received on or before the closing date

for comments, specified above, will be

considered before taking action on the

proposed rule. The proposals contained

in this notice may be changed in light

of the comments received.

Comments are specifically invited on

the overall regulatory, economic,

environmental, and energy aspects of

the proposed rule. All comments

submitted will be available, both before

and after the closing date for comments,

in the Rules Docket for examination by

interested persons. A report

summarizing each FAA-public contact

concerned with the substance of this

proposal will be filed in the Rules

Docket.

Commenters wishing the FAA to

acknowledge receipt of their comments

submitted in response to this notice

must submit a self-addressed, stamped

postcard on which the following

statement is made: ‘‘Comments to

Docket Number 97–NM–173–AD.’’ The

postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this

NPRM by submitting a request to the

FAA, Transport Airplane Directorate,

ANM–103, Attention: Rules Docket No.

97–NM–173–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

In October 1994, a transport category

airplane was involved in an accident in

which severe icing conditions [believed

to be composed of freezing drizzle or

supercooled large droplets (SLD)] were

reported in the area. Loss of control of

the airplane may have occurred because

ice accretion on the upper surface of the

wing aft of the area protected by the ice

protection system caused airflow

separation, which resulted in the

ailerons being forced to a right-wingdown control position. There also is

concern that the autopilot, which was
48554 Federal Register / Vol. 62, No. 179 / Tuesday, September 16, 1997 / Proposed Rules

engaged, may have masked the unusual

control forces generated by the ice

accumulation. These conditions, if not

corrected, could result in a roll upset

from which the flight crew may be

unable to recover.

The atmospheric conditions (freezing

drizzle or SLD conditions) that may

have contributed to the accident are

outside the icing envelope specified in

Appendix C of part 25 of the Federal

Aviation Regulations (14 CFR part 25)

for certification of the airplane. Such

icing conditions are not defined in

Appendix C, and the FAA has not

required that airplanes be shown to be

capable of operating safely in those

icing conditions.

The FAA finds that flight crews are

not currently provided with adequate

information necessary to determine

when the airplane is operating in icing

conditions for which the airplane is not

certificated or what action to take when

such conditions are encountered.

Therefore, the FAA has determined that

flight crews must be provided with such

information and must be made aware of

certain visual cues that may indicate the

airplane is operating in atmospheric

conditions that are outside the icing

envelope.

Since such information is not

available to flight crews, and no

airplane is certificated for operation in

severe icing conditions, such as freezing

drizzle or SLD conditions, the FAA

finds that the potentially unsafe

condition (described previously as

control difficulties following operation

of the airplane in icing conditions

outside of the icing envelope) is not

limited to airplanes having the same

type design as that of the accident

airplane.

The FAA recognizes that the flight

crew of any airplane that is certificated

for flight in icing conditions may not

have adequate information concerning

flight in icing conditions outside the

icing envelope. However, in 1996, the

FAA found that the specified unsafe

condition must be addressed as a higher

priority on airplanes equipped with

pneumatic deicing boots and

unpowered roll control systems. These

airplanes were addressed first because

the flight crew of an airplane having an

unpowered roll control system must

rely solely on physical strength to

counteract roll control anomalies,

whereas a roll control anomaly that

occurs on an airplane having a powered

roll control system need not be offset

directly by the flight crew. The FAA

also placed a priority on airplanes that

are used in regularly scheduled

passenger service. The FAA issued the

following airworthiness directives (AD)

that addressed airplanes that met these

criteria. These AD’s identified visual

cues for recognizing severe icing

conditions, procedures for exiting these

conditions, and prohibitions on the use

of various flight control devices. These

AD’s consisted of the following airplane

models:

Docket No. Manufacturer/airplane model Federal Register

citation

96–CE–01–AD .................... de Havilland DHC–6 Series ............................................................................................................. 61 FR 2175

96–CE–02–AD .................... EMBRAER EMB–110P1/EMB–110P2 ............................................................................................. 61 FR 2183

96–CE–03–AD .................... Beech 99/200/1900 Series .............................................................................................................. 61 FR 2180

96–CE–04–AD .................... Dornier 228 Series ........................................................................................................................... 61 FR 2172

96–CE–05–AD .................... Cessna 208/208B ............................................................................................................................ 61 FR 2178

96–CE–06–AD .................... Fairchild Aircraft SA226/SA227 Series ............................................................................................ 61 FR 2189

96–CE–07–AD .................... Jetstream 3101/3201 ....................................................................................................................... 61 FR 2186

96–NM–13–AD ................... Jetstream BAe ATP ......................................................................................................................... 61 FR 2144

96–NM–14–AD ................... Jetstream 4101 ................................................................................................................................ 61 FR 2142

96–NM–15–AD ................... British Aerospace HS 748 Series .................................................................................................... 61 FR 2139

96–NM–16–AD ................... Saab SF340A/SAAB 340B/SAAB 2000 Series ............................................................................... 61 FR 2169

96–NM–17–AD ................... CASA C–212/CN–235 Series .......................................................................................................... 61 FR 2166

96–NM–18–AD ................... Dornier 328–100 Series ................................................................................................................... 61 FR 2157

96–NM–19–AD ................... EMBRAER EMB–120 Series ........................................................................................................... 61 FR 2163

96–NM–20–AD ................... de Havilland DHC–7/DHC–8 Series ................................................................................................ 61 FR 2154

96–NM–21–AD ................... Fokker F27 Mark 100/200/300/400/500/600/700/050 Series .......................................................... 61 FR 2160

96–NM–22–AD ................... Short Brothers SD3–30/SD3–60/SD3–SHERPA Series ................................................................. 61 FR 2151

95–NM–146–AD ................. Aerospatiale ATR–42/ATR–72 Series ............................................................................................. 61 FR 2147

Since issuance of those AD’s, the FAA has determined that similar AD’s should be issued for similarly equipped

airplanes that are not used in regularly scheduled passenger service. Like the AD’s written in 1996, the proposed

rules, described below, also would provide visual cues for recognizing severe icing conditions, procedures for exiting

these conditions, and prohibitions on the use of various flight control devices. These proposed rules would apply

to part 25 and certain part 23 airplanes that are equipped with unpowered roll controls and pneumatic deicing boots.

The part 23 NPRM’s address airplanes certificated in normal and utility categories (not used in agricultural operations)

that are used in part 135 on-demand and air-taxi operation, and other airplanes regularly exposed to icing conditions.

The proposed rules affect the following airplanes:

Airplane models Docket No.

Aerospace Technologies of Australia, Models N22B and N24A ...................................................................................................... 97–CE–49–AD

Harbin Aircraft Mfg. Corporation, Model Y12 IV ............................................................................................................................... 97–CE–50–AD

Partenavia Costruzioni Aeronauticas, S.p.A. Models P68, AP68TP 300, AP68TP 600 .................................................................. 97–CE–51–AD

Industrie Aeronautiche e Meccaniche, Rinaldo Piaggio S.p.A. Model P–180 ................................................................................. 97–CE–52–AD

Pilatus Aircraft Ltd., Models PC–12 and PC–12/45 ......................................................................................................................... 97–CE–53–AD

Pilatus Britten-Norman Ltd., Models BN–2A, BN–2B, and BN–2T .................................................................................................. 97–CE–54–AD

SOCATA—Groupe Aerospatiale, Model TBM–700 .......................................................................................................................... 97–CE–55–AD

Aerostar Aircraft Corporation, Models PA–60–600, –601, –601P, –602P, and –700P ................................................................... 97–CE–56–AD

Twin Commander Aircraft Corporation, Models 500, –500–A, –500–B, –500–S, –500–U, –520, –560, –560–A, –560–E, –560–

F, –680, –680–E, and –680FL(P).

97–CE–57–AD

Beech Aircraft Corporation (Raytheon), Models E55, E55A, 58, 58A, 58P,58PA, 58TC, 58TCA, 60 series, 65–B80 series, 65–

B–90 series, 90 series, F90 series, 100 series, 300 series, and B300 series.

97–CE–58–AD

Beech Aircraft Corporation (Raytheon), Model 2000 ....................................................................................................................... 97–CE–59–AD
Federal Register / Vol. 62, No. 179 / Tuesday, September 16, 1997 / Proposed Rules 48555

Airplane models Docket No.

The New Piper Aircraft, Inc., Models PA–46 –310P and PA–46–350P .......................................................................................... 97–CE–60–AD

Piper Aircraft Corporation, Models PA–23, PA–23–160, PA–23–235, PA–23–250, PA–E23–250, PA–30, PA–39, PA–40, PA–

31, PA–31–300, PA–31–325, PA–31–350, PA–34–200, PA–34–200T, PA–34–220T, PA–42, PA–42–720, PA–42–1000.

97–CE–61–AD

Cessna Aircraft Company, Models P210N, T210N, P210R, 501, and 551 ..................................................................................... 97–CE–62–AD

Cessna Aircraft Company, Models T303, 310R, T310R, 335, 340A, 402B, 402C, 404, F406, 414, 414A, 421B, 421C, 425, and

441.

97–CE–63–AD

SIAI–Marchetti S.r.I. (Augusta), Models SF600 and SF600A .......................................................................................................... 97–CE–64–AD

Cessna Aircraft Company, Models 500, 550, and 560 Series Airplanes ......................................................................................... 97–NM–170–AD

Sabreliner Corporation, Models 40, 60, 70, and 80 Series Airplanes ............................................................................................. 97–NM–171–AD

Gulfstream Aerospace, Model G–159 Series Airplanes ................................................................................................................... 97–NM–172–AD

McDonnell Douglas, Models DC–3 and DC–4 Series Airplanes ..................................................................................................... 97–NM–173–AD

Mitsubishi Heavy Industries, Model YS–11 and YS–11A Series Airplanes ..................................................................................... 97–NM–174–AD

Frakes Aviation, Model G–73 (Mallard) and G–73T Series Airplanes ............................................................................................. 97–NM–175–AD

Lockheed, Models L–14 and L–18 Series Airplanes ........................................................................................................................ 97–NM–176–AD

Fairchild, Models F27 and FH227 Series Airplanes ......................................................................................................................... 97–NM–177–

AD.

The FAA’s Determination

Following examination of all relevant

information, the FAA has determined

that certain limitations and procedures

should be included in the FAAapproved Airplane Flight Manual

(AFM) for the affected airplanes as

follows:

• All McDonnell Douglas Model DC–

3 and DC–4 series airplanes must be

prohibited from flight in severe icing

conditions (as determined by certain

visual cues), and

• Flight crews must be provided with

information that would minimize the

potential hazards associated with

operating the airplane in severe icing

conditions.

The FAA has determined that such

limitations and procedures currently are

not defined adequately in the AFM for

these airplanes.

Explanation of the Provisions of the

Proposed AD

Since an unsafe condition has been

identified in which an unrecoverable

roll upset may occur as a result of

exposure to severe icing conditions that

are outside the icing limits for which

the airplane was certificated, the

proposed AD would require revising the

Limitations Section of the FAAapproved AFM to specify procedures

that would:

• require flight crews to immediately

request priority handling from Air

Traffic Control to exit severe icing

conditions (as determined by certain

visual cues)

• prohibit flight in severe icing

conditions (as determined by certain

visual cues)

• prohibit use of the autopilot when

ice is formed aft of the protected

surfaces of the wing, or when an

unusual lateral trim condition exists;

and

• require that all wing icing

inspection lights be operative prior to

flight into known or forecast icing

conditions at night.

This proposed AD would also require

revising the Normal Procedures Section

of the FAA-approved AFM to specify

procedures that would:

• limit the use of the flaps and

prohibit the use of the autopilot when

ice is observed forming aft of the

protected surfaces of the wing, or if

unusual lateral trim requirements or

autopilot trim warnings are

encountered; and

• provide the flight crew with

recognition cues for, and procedures for

exiting from, severe icing conditions.

Cost Impact

There are approximately 300

McDonnell Douglas Model DC–3 and

DC–4 series airplanes of the affected

design in the worldwide fleet. The FAA

estimates that 166 airplanes of U.S.

registry would be affected by this

proposed AD, that it would take

approximately 1 work hour per airplane

to accomplish the proposed actions, and

that the average labor rate is $60 per

work hour. Based on these figures, the

cost impact of the proposed AD on U.S.

operators is estimated to be $9,960, or

$60 per airplane.

The cost impact figure discussed

above is based on assumptions that no

operator has yet accomplished any of

the proposed requirements of this AD

action, and that no operator would

accomplish those actions in the future if

this AD were not adopted.

In addition, the FAA recognizes that

the proposed action may impose

operational costs. However, these costs

are incalculable because the frequency

of occurrence of the specified

conditions and the associated additional

flight time cannot be determined.

Nevertheless, because of the severity of

the unsafe condition, the FAA has

determined that continued operational

safety necessitates the imposition of the

costs.

Regulatory Impact

The regulations proposed herein

would not have substantial direct effects

on the States, on the relationship

between the national government and

the States, or on the distribution of

power and responsibilities among the

various levels of government. Therefore,

in accordance with Executive Order

12612, it is determined that this

proposal would not have sufficient

federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I

certify that this proposed regulation (1)

is not a ‘‘significant regulatory action’’

under Executive Order 12866; (2) is not

a ‘‘significant rule’’ under the DOT

Regulatory Policies and Procedures (44

FR 11034, February 26, 1979); and (3) if

promulgated, will not have a significant

economic impact, positive or negative,

on a substantial number of small entities

under the criteria of the Regulatory

Flexibility Act. A copy of the draft

regulatory evaluation prepared for this

action is contained in the Rules Docket.

A copy of it may be obtained by

contacting the Rules Docket at the

location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation

safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the Federal Aviation

Administration proposes to amend part

39 of the Federal Aviation Regulations

(14 CFR part 39) as follows:
48556 Federal Register / Vol. 62, No. 179 / Tuesday, September 16, 1997 / Proposed Rules

PART 39—AIRWORTHINESS

DIRECTIVES

1. The authority citation for part 39

continues to read as follows:

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

§39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

McDonnell Douglas: Docket 97–NM–173–AD.

Applicability: All Model DC–3 and DC–4

series airplanes, certificated in any category.

Note 1: This AD applies to each airplane

identified in the preceding applicability

provision, regardless of whether it has been

modified, altered, or repaired in the area

subject to the requirements of this AD. For

airplanes that have been modified, altered, or

repaired so that the performance of the

requirements of this AD is affected, the

owner/operator must request approval for an

alternative method of compliance in

accordance with paragraph (b) of this AD.

The request should include an assessment of

the effect of the modification, alteration, or

repair on the unsafe condition addressed by

this AD; and, if the unsafe condition has not

been eliminated, the request should include

specific proposed actions to address it.

Compliance: Required as indicated, unless

accomplished previously.

To minimize the potential hazards

associated with operating the airplane in

severe icing conditions by providing more

clearly defined procedures and limitations

associated with such conditions, accomplish

the following:

(a) Within 30 days after the effective date

of this AD, accomplish the requirements of

paragraphs (a)(1) and (a)(2) of this AD.

Note 2: Operators should initiate action to

notify and ensure that flight crewmembers

are apprised of this change.

(1) Revise the FAA-approved Airplane

Flight Manual (AFM) by incorporating the

following into the Limitations Section of the

AFM. This may be accomplished by inserting

a copy of this AD in the AFM.

‘‘Warning

Severe icing may result from

environmental conditions outside of those for

which the airplane is certificated. Flight in

freezing rain, freezing drizzle, or mixed icing

conditions (supercooled liquid water and ice

crystals) may result in ice build-up on

protected surfaces exceeding the capability of

the ice protection system, or may result in ice

forming aft of the protected surfaces. This ice

may not be shed using the ice protection

systems, and may seriously degrade the

performance and controllability of the

airplane.

• During flight, severe icing conditions

that exceed those for which the airplane is

certificated shall be determined by the

following visual cues. If one or more of these

visual cues exists, immediately request

priority handling from Air Traffic Control to

facilitate a route or an altitude change to exit

the icing conditions.

—Unusually extensive ice accumulation on

the airframe and windshield in areas not

normally observed to collect ice.

—Accumulation of ice on the upper surface

of the wing aft of the protected area.

—Accumulation of ice on the engine nacelles

and propeller spinners farther aft than

normally observed.

• Since the autopilot, when installed and

operating, may mask tactile cues that indicate

adverse changes in handling characteristics,

use of the autopilot is prohibited when any

of the visual cues specified above exist, or

when unusual lateral trim requirements or

autopilot trim warnings are encountered

while the airplane is in icing conditions.

• All wing icing inspection lights must be

operative prior to flight into known or

forecast icing conditions at night. [NOTE:

This supersedes any relief provided by the

Master Minimum Equipment List (MMEL).]’’

(2) Revise the FAA-approved AFM by

incorporating the following into the Normal

Procedures Section of the AFM. This may be

accomplished by inserting a copy of this AD

in the AFM.

‘‘THE FOLLOWING WEATHER

CONDITIONS MAY BE CONDUCIVE TO

SEVERE IN-FLIGHT ICING

• Visible rain at temperatures below 0

degrees Celsius ambient air temperature.

• Droplets that splash or splatter on impact

at temperatures below 0 degrees Celsius

ambient air temperature.

PROCEDURES FOR EXITING THE SEVERE

ICING ENVIRONMENT

These procedures are applicable to all

flight phases from takeoff to landing. Monitor

the ambient air temperature. While severe

icing may form at temperatures as cold as

¥18 degrees Celsius, increased vigilance is

warranted at temperatures around freezing

with visible moisture present. If the visual

cues specified in the Limitations Section of

the AFM for identifying severe icing

conditions are observed, accomplish the

following:

• Immediately request priority handling

from Air Traffic Control to facilitate a route

or an altitude change to exit the severe icing

conditions in order to avoid extended

exposure to flight conditions more severe

than those for which the airplane has been

certificated.

• Avoid abrupt and excessive

maneuvering that may exacerbate control

difficulties.

• Do not engage the autopilot.

• If the autopilot is engaged, hold the

control wheel firmly and disengage the

autopilot.

• If an unusual roll response or

uncommanded roll control movement is

observed, reduce the angle-of-attack.

• Do not extend flaps when holding in

icing conditions. Operation with flaps

extended can result in a reduced wing angleof-attack, with the possibility of ice forming

on the upper surface further aft on the wing

than normal, possibly aft of the protected

area.

• If the flaps are extended, do not retract

them until the airframe is clear of ice.

• Report these weather conditions to Air

Traffic Control.’’

(b) An alternative method of compliance or

adjustment of the compliance time that

provides an acceptable level of safety may be

used if approved by the Manager, Los

Angeles Aircraft Certification Office (ACO),

FAA, Transport Airplane Directorate. The

request shall be forwarded through an

appropriate FAA Operations Inspector, who

may add comments and then send it to the

Manager, Los Angeles ACO.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

(c) Special flight permits may be issued in

accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to

a location where the requirements of this AD

can be accomplished.

Issued in Renton, Washington, on

September 10, 1997.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–24503 Filed 9–15–97; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–NM–171–AD]

RIN 2120–AA64

Airworthiness Directives; Sabreliner

Model 40, 60, 70, and 80 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to

certain Sabreliner Model 40, 60, 70, and

80 series airplanes. This proposal would

require revising the Airplane Flight

Manual (AFM) to specify procedures

that would prohibit flight in severe icing

conditions (as determined by certain

visual cues), limit or prohibit the use of

various flight control devices while in

severe icing conditions, and provide the

flight crew with recognition cues for,

and procedures for exiting from, severe

icing conditions. This proposal is

prompted by results of a review of the

requirements for certification of the

airplane in icing conditions, new

information on the icing environment,

and icing data provided currently to the

flight crews. The actions specified by

the proposed AD are intended to

minimize the potential hazards

associated with operating the airplane