Federal Register / Vol. 61, No. 17 / Thursday, January 25, 1996 / Proposed Rules 2147

Compliance: Required as indicated, unless

accomplished previously.

To minimize the potential hazards

associated with operating the airplane in

freezing rain or freezing drizzle 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 must 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.

‘‘• Flight in meteorological conditions

described as freezing rain or freezing drizzle,

as determined by the following visual cues,

is prohibited:

—Unusually extensive ice accreted on the

airframe in areas not normally observed to

collect ice.

—Accumulation of ice on the upper surface

(for low-wing airplanes) or lower surface

(for high-wing airplanes) of the wing aft of

the protected area.

—Accumulation of ice on the propeller

spinner farther back than normally

observed.

If the airplane encounters conditions that

are determined to contain freezing rain or

freezing drizzle, the pilot must immediately

exit the freezing rain or freezing drizzle

conditions by changing altitude or course.

Note: The prohibition on flight in freezing

rain or freezing drizzle is not intended to

prohibit purely inadvertent encounters with

the specified meteorological conditions.

However, pilots should make all reasonable

efforts to avoid such encounters and must

immediately exit the conditions if they are

encountered.

• Use of the autopilot is prohibited when

any ice is observed forming aft of the

protected surfaces of the wing, or when

unusual lateral trim requirements or

autopilot trim warnings are encountered.

Note: The autopilot may mask tactile cues

that indicate adverse changes in handling

characteristics. Therefore, the pilot should

consider not using the autopilot when any

ice is visible on the airplane.

• All icing detection lights must be

operative prior to flight into 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.

‘‘WARNING

‘‘If ice is observed forming aft of the

protected surfaces of the wing, or if unusual

lateral trim requirements or autopilot trim

warnings are encountered:

• If the flaps are extended, do not retract

them until the airframe is clear of ice.

• The flight crew should reduce the angleof-attack by increasing speed as much as the

airplane configuration and weather allow,

without exceeding design maneuvering

speed.

• If the autopilot is engaged, hold the

control wheel firmly and disengage the

autopilot. Do not re-engage the autopilot

until the airframe is clear of ice.

• Exit the icing area immediately by

changing altitude or course.

• Report these weather conditions to Air

Traffic Control.

CAUTION

Severe icing comprises 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 extreme 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.

THE FOLLOWING SHALL BE USED TO

IDENTIFY FREEZING RAIN/FREEZING

DRIZZLE ICING CONDITIONS:

• Unusually extensive ice accreted on the

airframe in areas not normally observed to

collect ice.

• Accumulation of ice on the upper

surface (for low-wing airplanes) or lower

surface (for high-wing airplanes) of the wing

aft of the protected area.

• Accumulation of ice on the propeller

spinner farther back than normally observed.

THE FOLLOWING MAY BE USED TO

IDENTIFY POSSIBLE FREEZING RAIN/

FREEZING DRIZZLE CONDITIONS:

• Visible rain at temperatures below +5

degrees Celsius [outside air temperature

(OAT)].

• Droplets that splash or splatter on impact

at temperatures below +5 degrees Celsius

OAT.

PROCEDURES FOR EXITING THE

FREEZING RAIN/FREEZING DRIZZLE

ENVIRONMENT:

These procedures are applicable to all

flight phases from takeoff to landing. Monitor

the outside 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 AFM for identifying

possible freezing rain or freezing drizzle

conditions are observed, accomplish the

following:

• Exit the freezing rain or freezing drizzle

severe icing conditions immediately to avoid

extended exposure to flight conditions

outside of those for which the airplane has

been certificated for operation. Asking for

priority to leave the area is fully justified

under these conditions.

• Avoid abrupt and excessive

maneuvering that may exacerbate control

difficulties.

• Do not engage the autopilot. The

autopilot may mask unusual control system

forces.

• If the autopilot is engaged, hold the

control wheel firmly and disengage the

autopilot.

• If an unusual roll response or

uncommanded control movement is

observed, reduce the angle-of-attack by

increasing airspeed or rolling wings level (if

in a turn), and apply additional power, if

needed.

• Avoid extending flaps during extended

operation in icing conditions. Operation with

flaps extended can result in a reduced wing

angle-of- attack, with ice forming on the

upper surface further aft on the wing than

normal, possibly aft of the protected area.

• 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,

Standardization Branch, ANM–113, FAA,

Transport Airplane Directorate. Operators

shall submit their requests through an

appropriate FAA Principal Operations

Inspector, who may add comments and then

send it to the Manager, Standardization

Branch, ANM–113.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Standardization Branch,

ANM–113.

(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 January

19, 1996.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 96–1169 Filed 1–24–96; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 95–NM–146–AD]

Airworthiness Directives; Aerospatiale

Model ATR–42 and ATR–72 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Supplemental notice of

proposed rulemaking; reopening of

comment period.

SUMMARY: This document revises an

earlier proposed airworthiness directive

(AD) that is applicable to all

Aerospatiale Model ATR–42 and ATR–

72 series airplanes. That proposal would

have superseded an existing AD to

prohibit operation of the airplane in

certain icing conditions unless

modifications are accomplished or

alternative procedures and training are

adopted, and to require restrictions on
2148 Federal Register / Vol. 61, No. 17 / Thursday, January 25, 1996 / Proposed Rules

the use of the autopilot in certain

conditions. That proposal also would

have added requirements for

modification of the deicing boots on the

leading edge of the wing and various

follow-on actions. That proposal was

prompted by an FAA determination

that, during flight in certain icing

conditions, and with the airplane in a

specific flight configuration, a ridge of

ice can form on the wing and cause an

interruption in the airflow over the

ailerons, aileron deflection, and

resultant lateral control forces. This

action revises the originally proposed

rule by removing certain limitations and

procedures. The actions specified by

this proposed AD are intended to

prevent a roll upset from which the

flight crew may be unable to recover.

DATES: Comments must be received by

March 7, 1996.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 95–NM–

146–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.

The service information referenced in

the proposed rule may be obtained from

Aerospatiale, 316 Route de Bayonne,

31060 Toulouse, Cedex 03, France. This

information may be examined at the

FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: Gary

Lium, Aerospace Engineer,

Standardization Branch, ANM–113,

FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington 98055–4056; telephone

(206) 227–1112; fax (206) 227–1149.

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 95–NM–146–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.

95–NM–146–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

A proposal to amend part 39 of the

Federal Aviation Regulations (14 CFR

part 39) to add an airworthiness

directive (AD), applicable to all

Aerospatiale Model ATR–42 and ATR–

72 series airplanes, was published as a

notice of proposed rulemaking (NPRM)

in the Federal Register on October 18,

1995 (60 FR 53883). That NPRM would

have superseded an existing AD to

prohibit operation of the airplane in

certain icing conditions unless

modifications are accomplished or

alternative procedures and training are

adopted, and to require restrictions on

the use of the autopilot in certain

conditions. That proposal also would

have added requirements for

modification of the deicing boots on the

leading edge of the wing and various

follow-on actions. That NPRM was

prompted by an FAA determination

that, during flight in certain icing

conditions, and with the airplane in a

specific flight configuration, a ridge of

ice can form on the wing and cause an

interruption in the airflow over the

ailerons, aileron deflection, and

resultant lateral control forces. That

condition, if not corrected, could result

in a roll upset from which the flight

crew may be unable to recover.

Further Examination of Atmospheric

Conditions

Since the issuance of that NPRM, the

FAA has further examined the

atmospheric conditions that may have

contributed to an accident involving a

Model ATR–72 series airplane that

encountered severe icing conditions

(believed to be composed of freezing

drizzle size droplets) while the airplane

was enroute from Indianapolis to

Chicago. Those atmospheric conditions

(freezing drizzle) 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. Freezing

rain is an atmospheric condition that

also is outside the icing envelope. 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.

Information Currently Provided to

Flight Crews

The FAA finds that, in general, 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.

Effect of Unsafe Condition on Other

Airplanes

Since such information is not

available to flight crews, and no

airplane is certificated for operation in

freezing drizzle 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, the FAA finds

that the specified unsafe condition must

be addressed as a higher priority on

airplanes that are

turbopropellerpowered and have

unpowered control systems. Many of

these airplanes carry passengers in

regularly scheduled revenue service in

the United States. Since

turbopropellerpowered airplanes are

more likely to operate at low altitudes

and to make more frequent landings,

they are more likely to encounter icing

conditions that are outside the icing

envelope. Additionally, the flight crew

of an airplane having an unpowered roll
Federal Register / Vol. 61, No. 17 / Thursday, January 25, 1996 / Proposed Rules 2149

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.

Review of Other TurbopropellerPowered Airplanes

Subsequent to the accident, the FAA,

in conjunction with certain foreign

airworthiness authorities and airplane

manufacturers, conducted reviews of

certain transport and small category

airplanes to determine if any airplanes

might experience control difficulty

should a ridge of ice form aft of the

deicing boots and forward of the

ailerons. The review focused on

turbopropeller-powered airplanes

having unpowered roll control systems,

since those airplanes are similar in

design to the accident airplane and

because they are frequently exposed to

icing conditions.

During the reviews of these airplanes,

an artificial ice shape was used in the

demonstration of roll control

characteristics. This ice shape was

chosen as representative of a shape that

might form if an airplane were operated

in freezing drizzle. Results of these

reviews revealed that certain airplanes

demonstrated acceptable roll control

forces. However, the dynamics of ice

accretion in freezing drizzle are not well

understood, and the FAA recognizes

that such airplanes could develop ice

shapes other than those tested during

the review. Upon further review, the

FAA may consider additional

rulemaking.

Relevant Service Information Issued

Aerospatiale has issued Service

Bulletins ATR42–57–0043, ATR72–57–

1015, and ATR–72–57–1016, all dated

April 10, 1995. These service bulletins

describe procedures for modification of

the deicing boots on the outer leading

edges of the wing. The modification

entails replacing the existing leading

edges with leading edges having wider

deicers. Accomplishment of this

modification will provide increased

protection against severe icing

conditions by increasing the effective

area of the deicing boots.

Conclusion

Following examination of all relevant

information, the FAA has determined

that certain procedures and

requirements specified in the original

NPRM for Model ATR–42 and ATR–72

series airplanes are unnecessary.

Further, the FAA finds that the

limitations and procedures listed below

adequately address the unsafe condition

associated with inadvertent flight into

freezing rain or freezing drizzle:

• Aerospatiale Model ATR–42 and

ATR–72 series airplanes must be

prohibited from flight in freezing rain or

freezing drizzle 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 freezing rain or

freezing drizzle conditions.

The FAA has determined that such

limitations and procedures currently are

not defined adequately in the AFM for

these airplanes. These same limitations

and procedures are the subject of

additional rulemaking actions that affect

several other turbopropeller-powered

airplanes.

This airplane model is manufactured

in France and is type certificated for

operation in the United States under the

provisions of section 21.29 of the

Federal Aviation Regulations (14 CFR

21.29) and the applicable bilateral

airworthiness agreement.

Explanation of the Provisions of this

Proposed AD

Since an unsafe condition has been

identified that is likely to exist or

develop on other airplanes of the same

type design, the proposed AD would

require revising the Limitations Section

of the AFM to specify procedures that

would:

• Prohibit flight in freezing rain or

freezing drizzle 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;

• Require that all icing detection

lights be operative prior to flight into

icing conditions at night; and

• Require that the ice detector be

operative for flight into icing conditions.

The prohibition on flight in freezing

rain or freezing drizzle is not intended

to prohibit purely inadvertent

encounters with the specified

atmospheric conditions. However, pilots

should make all reasonable efforts to

avoid such encounters and must

immediately exit the conditions if they

are encountered.

This proposed AD also would require

revising the Normal Procedures Section

of the 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.

This proposed AD also would require

modification of the deicing boots on the

outer leading edges of the wing.

Since these changes revise the scope

of the originally proposed rule, the FAA

has determined that it is necessary to

reopen the comment period to provide

additional opportunity for public

comment.

Cost Impact

The FAA estimates that 158 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 $9,480, or

$60 per airplane.

For Model ATR–42 series airplanes,

Modification 4216 (or 4222), as

proposed in this AD, would take

approximately 52 work hours per

airplane to accomplish, at an average

labor rate of $60 per work hour.

Required parts would be supplied by

the manufacturer at no cost to operators.

Based on these figures, the cost impact

on U.S. operators for this proposed

modification is estimated to be

$492,960, or $3,120 per airplane.

For Model ATR–72 series airplanes,

Modification 4215 (or 4221), as

proposed in this AD, would take

approximately 96 work hours per

airplane to accomplish. Required parts

for this modification would be supplied

by the manufacturer at no cost to

operators. Modification 4213, as

proposed in this AD, would take

approximately 4 work hours to

accomplish. Required parts would cost

approximately $200 per airplane. The

average labor rate for accomplishment of

both modifications is $60 per work

hour. Based on these figures, the cost

impact on U.S. operators for these

proposed modifications is estimated to

be $979,600, or $6,200 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

this proposed AD may impose

operational costs. However, those costs

are incalculable because the frequency

of occurrence of the specified

conditions and the associated additional
2150 Federal Register / Vol. 61, No. 17 / Thursday, January 25, 1996 / Proposed Rules

flight time are indeterminable.

Nevertheless, because of the severity of

the unsafe condition addressed, the

FAA has determined that continued

operational safety necessitates the

imposition of these 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:

PART 39—AIRWORTHINESS

DIRECTIVES

1. The authority citation for part 39

continues to read as follows:

Authority: 49 USC 106(g), 40113, 44701.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

Aerospatiale: Docket 95–NM–146–AD.

Applicability: All Model ATR–42 and

ATR–72 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 use the authority

provided in paragraph (d) of this AD to

request approval from the FAA. This

approval may address either no action, if the

current configuration eliminates the unsafe

condition; or different actions necessary to

address the unsafe condition described in

this AD. Such a request should include an

assessment of the effect of the changed

configuration on the unsafe condition

addressed by this AD. In no case does the

presence of any modification, alteration, or

repair remove any airplane from the

applicability of this AD.

Compliance: Required as indicated, unless

accomplished previously.

To minimize the potential hazards

associated with operating the airplane in

freezing rain or freezing drizzle icing

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 must 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.

‘‘• Flight in meteorological conditions

described as freezing rain or freezing drizzle,

as determined by the following visual cue, is

prohibited:

Freezing rain and freezing drizzle are

characterized by ice covering all or a

substantial part of the unheated portion of

either forward side window, possibly

associated with water splashing and

streaming on the windshield.

The following also may be used as

secondary indications of possible freezing

rain/freezing drizzle conditions:

—Unusually extensive ice accreted on the

airframe in areas not normally observed to

collect ice.

—Accumulation of ice on the upper or lower

surface of the wing aft of the protected

area.

—Accumulation of ice on the propeller

spinner farther back than normally

observed.

If the airplane encounters conditions that

are determined to contain freezing rain or

freezing drizzle, the pilot must immediately

exit the freezing rain or freezing drizzle

conditions by changing altitude or course.

Note: The prohibition on flight in freezing

rain or freezing drizzle is not intended to

prohibit purely inadvertent encounters with

the specified meteorological conditions.

However, pilots should make all reasonable

efforts to avoid such encounters and must

immediately exit the conditions if they are

encountered.

• Use of the autopilot is prohibited when

any ice is observed forming aft of the

protected surfaces of the wing, when unusual

lateral trim requirements or autopilot trim

warnings are encountered, or when the side

window visual cue described in the

Limitations Section of the AFM is observed.

Note: The autopilot may mask tactile cues

that indicate adverse changes in handling

characteristics. Therefore, the pilot should

consider not using the autopilot when any

ice is visible on the airplane.

• All icing detection lights must be

operative prior to flight into icing conditions

at night. [Note: This supersedes any relief

provided by the Master Minimum Equipment

List (MMEL).]

• The ice detector must be operative for

flight into icing conditions.

(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.

‘‘WARNING

‘‘If ice is observed forming aft of the

protected surfaces of the wing, if unusual

lateral trim requirements or autopilot trim

warnings are encountered, or if the side

window visual cue described in the

Limitations Section of the AFM is observed:

• If the flaps are extended, do not retract

them until the airframe is clear of ice.

• The flight crew should reduce the angleof-attack by increasing speed as much as the

airplane configuration and weather allow,

without exceeding design maneuvering

speed.

• If the autopilot is engaged, hold the

control wheel firmly and disengage the

autopilot. Do not re-engage the autopilot

until the airframe is clear of ice.

• Exit the icing area immediately by

changing altitude or course.

• Report these weather conditions to Air

Traffic Control.

CAUTION

Severe icing comprises 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 extreme 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.

THE FOLLOWING SHALL BE USED TO

IDENTIFY FREEZING RAIN/FREEZING

DRIZZLE ICING CONDITIONS:

Freezing rain and freezing drizzle are

characterized by ice covering all or a

substantial part of the unheated portion of

either forward side window, possibly

associated with water splashing and

streaming on the windshield.

The following also may be used as

secondary indications of possible freezing

rain/freezing drizzle conditions:

• Unusually extensive ice accreted on the

airframe in areas not normally observed to

collect ice.

• Accumulation of ice on the upper or

lower surface of the wing aft of the protected

area.

• Accumulation of ice on the propeller

spinner farther back than normally observed.
Federal Register / Vol. 61, No. 17 / Thursday, January 25, 1996 / Proposed Rules 2151

• Visible rain at temperatures below +5

degrees Celsius [outside air temperature

(OAT)].

• Droplets that splash or splatter on impact

at temperatures below +5 degrees Celsius

OAT.

PROCEDURES FOR EXITING THE

FREEZING RAIN/FREEZING DRIZZLE

ENVIRONMENT:

These procedures are applicable to all

flight phases from takeoff to landing. Monitor

the outside 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 AFM for identifying

possible freezing rain or freezing drizzle

conditions are observed, accomplish the

following:

• Exit the freezing rain or freezing drizzle

severe icing conditions immediately to avoid

extended exposure to flight conditions

outside of those for which the airplane has

been certificated for operation. Asking for

priority to leave the area is fully justified

under these conditions.

• Avoid abrupt and excessive

maneuvering that may exacerbate control

difficulties.

• Do not engage the autopilot. The

autopilot may mask unusual control system

forces.

• If the autopilot is engaged, hold the

control wheel firmly and disengage the

autopilot.

• If an unusual roll response or

uncommanded control movement is

observed, reduce the angle-of-attack by

increasing airspeed or rolling wings level (if

in a turn), and apply additional power, if

needed.

• Avoid extending flaps during extended

operation in icing conditions. Operation with

flaps extended can result in a reduced wing

angle-of-attack, with ice forming on the

upper surface further aft on the wing than

normal, possibly aft of the protected area.

• Report these weather conditions to Air

Traffic Control.’’

(b) Within 6 months after the effective date

of this AD, modify the deicing boots on the

leading edges of the wing by accomplishing

either paragraph (b)(1) or (b)(2) of this AD, as

applicable.

(1) For Model ATR–42 series airplanes:

Accomplish Aerospatiale Modification 4216

(during retrofit) or 4222 (during production),

as applicable. Modification 4216 shall be

accomplished in accordance with

Aerospatiale Service Bulletin ATR42–30–

0059, Revision 1, dated April 10, 1995; and

ATR42–57–0043, dated April 10, 1995.

Modification 4222 shall be accomplished in

accordance with Aerospatiale Service

Bulletin ATR42–57–0043, dated April 10,

1995.

(2) For Model ATR–72 series airplanes:

Accomplish Aerospatiale Modification 4215

(during retrofit) or 4221 (during production),

as applicable. Modification 4215 shall be

accomplished in accordance with

Aerospatiale Service Bulletin ATR72–30–

1023, Revision 1, dated April 10, 1995;

ATR72–57–1015, dated April 10, 1995; and

ATR72–57–1016, dated April 10, 1995.

Modification 4221 shall be accomplished in

accordance with Aerospatiale Service

Bulletin ATR72–57–1015, dated April 10,

1995; and ATR72–57–1016, dated April 10,

1995.

(c) For Model ATR–72 series airplanes:

Within 6 months after the effective date of

this AD, install Aerospatiale Modification

4213, ‘‘Flaps Extension Inhibition above VFE

15 deg.,’’ in accordance with Aerospatiale

Service Bulletin ATR72–27–1039, dated

January 12, 1995.

(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,

Standardization Branch, ANM–113, FAA,

Transport Airplane Directorate. Operators

shall submit their requests through an

appropriate FAA Principal Operations

Inspector, who may add comments and then

send it to the Manager, Standardization

Branch, ANM–113.

Note 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Standardization Branch,

ANM–113.

(e) 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 January

19, 1996.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 96–1170 Filed 1–24–96; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 96–NM–22–AD]

Airworthiness Directives; Short

Brothers Model SD3–30, SD3–60, and

SD3–SHERPA 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

Short Brothers Model SD3–30, SD3–60,

and SD3–SHERPA series airplanes. This

proposal would require revising the

Airplane Flight Manual (AFM) to

specify procedures that would prohibit

flight in freezing rain or freezing drizzle

conditions (as determined by certain

visual cues), limit or prohibit the use of

various flight control devices, 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 freezing rain or

freezing drizzle conditions by providing

more clearly defined procedures and

limitations associated with such

conditions.

DATES: Comments must be received by

March 7, 1996.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 96–NM–

22–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, 1601 Lind Avenue, SW.,

Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Phil

Forde, Aerospace Engineer,

Standardization Branch, ANM–113,

FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington 98055–4056; telephone

(206) 227–2146; fax (206) 227–1149.

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