[Federal Register Volume 60, Number 201 (Wednesday, October 18, 1995)]
[Proposed Rules]
[Pages 53883-53888]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25836]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


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: Notice of proposed rulemaking (NPRM).

SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to all Aerospatiale Model ATR-
42 and ATR-72 series airplanes. Unless modifications are accomplished 
or alternative procedures and training are adopted, that AD currently 
prohibits operation of the airplane in certain icing conditions, and 
requires restrictions on the use of the autopilot in certain 
conditions. That AD 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. The actions specified by that AD are 
intended to prevent a roll upset from which the flight crew may be 
unable to recover. This action would add requirements for modification 
of the deicing boots on the leading edge of the wing and various 
follow-on actions.

DATES: Comments must be received by November 28, 1995.

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 

[[Page 53884]]
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

    On December 9, 1994, the FAA issued telegraphic AD T94-25-51, 
applicable to all Aerospatiale Model ATR-42 and ATR-72 series 
airplanes, to address an unsafe condition related to potential hazards 
associated with operation of those airplanes in icing conditions. That 
AD required an operational limitation that prohibits operation of the 
airplane when icing conditions [as defined in the Airplane Flight 
Manual (AFM)] are forecast or reported. It also required restrictions 
on the use of the autopilot in inadvertent icing encounters, when the 
airplane is operated in moderate or greater turbulence, or whenever any 
unusual lateral trim situation is observed.
    That AD action was prompted by data obtained following an accident 
involving a Model ATR-72 series airplane that occurred when the 
airplane was enroute from Indianapolis to Chicago. The accident 
occurred during the initial descent for approach to Chicago. The 
airplane had been in a holding pattern for more than 30 minutes with 
flaps at the 15-degree position; icing conditions and turbulence were 
reported in the area.
    The official cause of the accident has not been determined. 
However, preliminary information from the accident investigation 
indicates that, immediately after the autopilot disconnected, at an 
indicated airspeed of approximately 185 knots, the ailerons abruptly 
deflected in the right-wing-down direction, and the airplane entered an 
abrupt roll to the right, which was not corrected before the airplane 
impacted the ground.

Results of Flight Tests Conducted at Edwards Air Force Base, 
California

    Prior to the issuance of telegraphic AD T94-25-51, Aerospatiale 
conducted wind tunnel and ground tests in Toulouse, France. Subsequent 
to the issuance of that AD, Aerospatiale contracted with the United 
States Air Force (USAF) to conduct a series of flight tests at Edwards 
Air Force Base, California. The test program was developed in 
conjunction with the National Transportation Safety Board (NTSB), 
National Aeronautics and Space Administration (NASA), the USAF, the 
FAA, and the Direction Generale de l'Aviation Civile (DGAC), which is 
the airworthiness authority for France.
    During these tests, a Model ATR-72 series airplane flew in close 
formation behind an ``icing tanker,'' which is a specially modified 
aerial refueling airplane designed to create icing conditions by 
spraying supercooled water droplets on a test airplane during flight. 
Appendix C of part 25 of the Federal Aviation Regulations (14 CFR part 
25) defines droplet diameters, liquid water content, temperature, and 
horizontal extent parameters for testing leading to approval of flight 
in icing conditions. Water droplet diameters specified in part 25 of 
the Federal Aviation Regulations (FAR) for certification of transport 
category airplanes, and larger droplets well outside the diameters 
specified in part 25 of the FAR (commonly referred to as ``freezing 
rain or freezing drizzle''), were sprayed onto the leading edges of the 
outer wing and on other airplane surfaces to determine ice accretion 
characteristics of the various diameter droplets. Droplet diameters 
larger than those specified in part 25 of the FAR were tested since 
meteorological evidence exists indicating that the accident airplane 
encountered such large droplets (freezing rain or freezing drizzle) 
prior to the accident.
    Results of data from the numerous flight tests conducted revealed 
the following significant findings:

--Ice accretion characteristics of the normal diameter droplets, as 
specified in the FAR, were entirely satisfactory. This confirmed that 
Model ATR-42 and ATR-72 series airplanes comply fully with performance 
requirements relating to the icing envelope specified in part 25 of the 
FAR for certification of these airplanes.
--Results of additional testing that was conducted with large water 
droplets (outside certification standards) revealed that it is possible 
for ice to accrete aft of the wing boot surface during a 17-minute 
exposure to the tanker spray when the aircraft operates with the flaps 
set at 15 degrees. Results of flight tests conducted with the flaps set 
at 15 degrees indicated that a spanwise ridge could disrupt the flow of 
air over the aileron when the flaps are retracted to the zero-degree 
position. This interruption of airflow caused an uncommanded aileron 
deflection and resultant unusual lateral control forces. However, 
during the tests conducted, the forces required to control the aircraft 
were within limits specified by the FAR.
--Exposure to freezing rain or freezing drizzle on the forward side 
windows of the cockpit produced ice on a substantial part of the 
forward side windows. This ice accretion on the forward side windows 
does not appear when the airplane is flying in the icing conditions 
defined in part 25 of the FAR. This characteristic ice accretion begins 
to form within 30 seconds of the beginning of the encounter with 
freezing rain or freezing drizzle. Additionally, test data indicate 
that the flight crew can observe the accumulation of ice on the forward 
side windows at least several minutes before a significant amount of 
ice accumulates on the wings.

    The cause of the accident is still under investigation. However, in 
light of the findings discussed previously, the FAA has determined that 
if a Model ATR-42 or ATR-72 series airplane is in flight with the flaps 
set at 15 degrees during freezing rain or freezing drizzle, an unusual 
ridge of ice on the wing (aft of the ice protection boots) can accrete. 
This ridge can interrupt the airflow over the ailerons when the flaps 
are retracted to the zero-degree position. This interruption of airflow 
can cause an aileron deflection and resultant unusual lateral control 
forces. In actual operations, these unusual forces may result in a roll 
upset from which the flight crew may be unable to recover.

Explanation of the Provisions of AD 95-02-51

    In an effort to break the chain of events that may lead to an 
aircraft roll upset, the manufacturer developed a set of procedures to 
be followed if the airplane should inadvertently encounter freezing 
rain or freezing drizzle conditions. These procedures were based on 
results of the tests conducted at Edwards Air Force Base. These 
procedures prohibit dispatch into or operation in known or forecast 
freezing rain or freezing drizzle, provide the 

[[Page 53885]]
flight crew with a means to identify inadvertent encounters with 
freezing rain and freezing drizzle conditions, and describe appropriate 
corrective actions. Accomplishment of these procedures will ensure safe 
operation of the airplane while operating in all icing conditions, 
including inadvertent encounters with freezing rain or freezing 
drizzle.
    These procedures were incorporated into several documents and 
related actions, which formed the basis for the FAA to expand operation 
of Model ATR-42 and ATR-72 series airplanes beyond that defined in 
telegraphic AD T94-25-51. Subsequently, on February 13, 1995, the FAA 
issued AD 95-02-51, amendment 39-9152 (60 FR 9616, February 21, 1995) 
to mandate the procedures developed by the manufacturer and approved by 
the FAA. Unless modifications are accomplished or alternative 
procedures and training are adopted, that AD continues to require an 
operational limitation that prohibits operation of the airplane when 
icing conditions (as defined in the AFM) are forecast or reported; and 
restrictions on the use of the autopilot in inadvertent icing 
encounters, when the airplane is operated in moderate or greater 
turbulence, or whenever any unusual lateral trim situation is observed. 
That AD also permits, as an interim measure prior to installation of an 
FAA-approved modification, operation of the airplane into icing 
conditions, provided that certain actions have been accomplished, as 
follows:
    1. The FAA-approved AFM must be revised to incorporate ATR-42 AFM 
Temporary Revision 18, dated January 10, 1995 (for Model ATR-42 series 
airplanes); or ATR-72 AFM Temporary Revision 14, dated January 10, 1995 
(for Model ATR-72 series airplanes).
    2. All Model ATR-42 and ATR-72 flight crew members must attend an 
FAA-approved training course prior to flight in known or forecast icing 
conditions. This training course provides instruction in the 
recognition of characteristic ice accretion on the cockpit forward side 
windows. This course also defines the procedures designed to escape 
freezing rain and freezing drizzle conditions and to minimize the 
hazard posed by flight in freezing rain or freezing drizzle. Documents 
used in this training course include the following: ATR Icing 
Conditions Procedures Brochure, Version 1.0 or 2.0; ATR Technical 
Background Paper, Version 1.0, dated January 6, 1995; Flight Crew 
Operation Manual, Revision 20, dated January 11, 1995 (for Model ATR-42 
series airplanes); and Flight Crew Operation Manual, Revision 12, dated 
January 11, 1995 (for Model ATR-72 series airplanes).
    3. Operators must establish an FAA-approved system to provide 
forecasts and reports of freezing rain and freezing drizzle at enroute 
altitudes along the route of flight and at all airports considered in 
the flight planning process.
    4. Operators of Model ATR-72 series airplanes must install ATR 
Modification Number 4213 to eliminate the multi-function computer 
inhibition against flap extension. The modification permits movement of 
the flaps above limit speed to give crews more operational discretion 
in an emergency.
    That AD also provides for an optional terminating action, which, if 
accomplished, would terminate the requirements of the AD. The optional 
terminating action, which must be approved by the FAA, involves 
installing a modification that precludes the formation of hazardous ice 
accumulation during flight in freezing rain or freezing drizzle 
conditions. The AD requires that, upon accomplishment of the optional 
terminating action, ATR Modification Number 4213 must be removed from 
Model ATR-72 series airplanes.
    The expanded operation provided by AD 95-02-51 includes the 
resumption of dispatch of the airplane into or operation in known or 
forecast icing conditions. (However, as specified in the AFM revisions 
cited in that AD, flight into known or forecast freezing drizzle or 
freezing rain conditions continues to be prohibited.)
    The procedures provided by AD 95-02-51 were permitted as an interim 
measure to allow resumption of normal flight operations in icing 
conditions until June 1, 1995, at which time an FAA-approved 
modification was to have been developed, tested, approved, and 
installed. The AD specifies that if such a modification was not 
installed by June 1, 1995, operation of the airplane when icing 
conditions are forecast or reported would again be prohibited and 
restrictions on the use of the autopilot in certain conditions would 
again be required.

Explanation of a Letter to Affected Operators

    While AD 95-02-51 was being developed, the manufacturer was 
developing certain modifications to the deicing boots on the leading 
edges of the wing. Subsequently, Aerospatiale issued Service Bulletins 
ATR42-30-0059, Revision 1, dated April 10, 1995 (for Model ATR-42 
series airplanes), and ATR72-30-1023, Revision 1, dated April 10, 1995 
(for Model ATR-72 series airplanes). These service bulletins describe 
procedures for modification of the deicing boots by extending the 
coverage of the deicing boots on the leading edges of the outer wing. 
Accomplishment of the modification will increase the deiced area of the 
leading edges of the outer wing. [The Aerospatiale modification numbers 
are: 4216 (retrofit) and 4222 (production line), for Model ATR-42 
series airplanes; and 4215 (retrofit) and 4221 (production line), for 
Model ATR-72 series airplanes. These modifications were approved by the 
FAA on March 20, 1995, as type design changes to Model ATR-42 and ATR-
72 series airplanes.]
    During development of those modifications and following issuance of 
AD 95-02-51, it became clear to the FAA that installation of modified 
deicing boots alone would not be sufficient to ensure an acceptable 
level of safety. Consequently, the FAA determined that certain existing 
flight crew procedures specified currently in AD 95-02-51 must remain 
in place and must be used in conjunction with the modified deicing 
boots. Further, the FAA recognized that a new AD to mandate 
installation of the deicing boots and observation of flight crew 
procedures could not be completed before the June 1, 1995, deadline 
specified in AD 95-02-51, and that sufficient justification existed to 
extend that deadline.
    In light of this, the FAA approved an alternative method of 
compliance for the requirements of AD 95-02-51 in accordance with the 
provisions of paragraph (d) of that AD. This approval is contained in a 
letter that was distributed to all operators of the affected airplanes 
on May 26, 1995. The approval allowed continued operation of these 
airplanes in icing conditions beyond June 1, 1995, provided that 
certain additional procedures and restrictions were observed and 
modification of the deicing boots, as described previously, was 
accomplished.
    The specific additional procedures and restrictions specified in 
the letter to operators included the following:
    1. For Model ATR-72 series airplanes only, Aerospatiale 
Modification 4213, ``Flaps Extension Inhibition Above VFE 15 ,'' must 
be installed (or remain installed, if already accomplished). Procedures 
for accomplishment of the modification are contained in Aerospatiale 
Service Bulletin ATR72-27-1039, dated January 12, 1995. The 
modification removes the flap movement cutout at speeds greater than 

[[Page 53886]]
185 knots to provide flight crews more operational discretion in an 
emergency.
    2. Flight crew training based on the revised ATR Icing Procedures 
Brochure ``Freezing Drizzle: Towards a Better Knowledge and a Better 
Protection,'' Issue 1, dated May 11, 1995, must be conducted prior to 
flight in icing conditions, and at least annually thereafter, for all 
ATR-42 and ATR-72 flight crews. (Training conducted previously in 
compliance with AD 95-02-51 may serve as the initial training for 
purposes of computing the training interval.)
    3. ATR-42 AFM Temporary Revision 20, dated May 1995 (for Model ATR-
42 series airplanes), or ATR-72 AFM Temporary Revision 16, dated May 
1995 (for Model ATR-72 series airplanes), must be inserted into the 
Limitations Section of the respective AFM. These temporary revisions 
specify that dispatch or operation into known freezing rain or freezing 
drizzle conditions is prohibited. Once inserted, the AFM revision 
required by AD 95-02-51 may be removed.
    The FAA determined that observing the procedures and restrictions 
outlined above, in addition to installing modified deicing boots, will 
provide an additional margin of safety during flight in icing 
conditions or during an inadvertent encounter with freezing rain or 
freezing drizzle conditions. The FAA also determined that the 
procedures identified in the letter to operators will provide the 
flight crews with an acceptable means to identify and safely exit those 
conditions.
    It should be noted that the procedures specified in the letter to 
operators are essentially the same as those mandated by AD 95-02-51 
with the exception that the letter allows dispatch into forecast (but 
not actual or reported) freezing rain or freezing drizzle conditions, 
while the AD prohibits such dispatch. Based on its determination that 
installing the modifications and observing the operational procedures 
and restrictions discussed previously will provide an additional margin 
of safety while flying in icing conditions, the FAA finds that the 
restriction specified in AD 95-02-51 concerning dispatch into forecast 
(but not actual or reported) freezing drizzle or freezing rain 
conditions can be eliminated.

Explanation of the Provisions of the Proposed AD

    Based on the information discussed previously, and since an unsafe 
condition has been identified that is likely to exist or develop on 
other airplanes of the same type design registered in the United 
States, the FAA proposes to supersede AD 95-02-51 with a new AD with 
the following requirements:
    Unless modifications are accomplished or alternative procedures and 
training are adopted, the proposed AD would continue to prohibit 
operation of the airplane in certain icing conditions, and requires 
restrictions on the use of the autopilot in certain conditions.
    The proposed AD would require installation of the FAA-approved 
modification of the deicing boots on the leading edges of the wing, 
which must be used in conjunction with certain flight crew procedures. 
Accomplishment of the modification and observation of the flight crew 
procedures would terminate the requirements of AD 95-02-51, thereby 
allowing operation of the airplane in certain icing conditions, 
allowing use of the autopilot in certain conditions, and eliminating 
the restriction specified in that AD concerning dispatch into forecast 
(but not actual or reported) freezing drizzle or freezing rain 
conditions.
    In addition, the FAA finds that the requirement specified in AD 95-
02-51 for operators to establish an FAA-approved system to provide 
forecasts and reports of freezing rain and freezing drizzle at enroute 
altitudes along the route of flight and at all airports considered in 
the flight planning process must be retained in this proposed AD.
    The proposed actions would be required to be accomplished in 
accordance with various documents described previously.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this notice to clarify this long-standing requirement.

Cost Estimate

    The airplane models affected by this proposed AD action are 
manufactured in France and are 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.
    There are approximately 158 Model ATR-42 and ATR-72 series 
airplanes of U.S. registry that would be affected by this proposed AD.
    The AFM revision that is currently required by AD 95-02-51 takes 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the total cost 
impact on U.S. operators of the actions currently required is estimated 
to be $9,480, or $60 per airplane.
    The AFM revision that is proposed in this AD would take 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the total cost 
impact on U.S. operators for the proposed AFM revision is estimated to 
be $9,480, or $60 per airplane.
    Accomplishment of training concerning the use of icing forecasts 
and reports, as proposed in this AD, would be approximately $300,000 
annually, or $1,900 per airplane. Accomplishment of flight crew 
training based on the Icing Procedures Brochure discussed previously, 
as proposed in this AD, would cost approximately $150,000 annually, or 
$950 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 total 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 total cost impact on U.S. 
operators for these proposed modifications is estimated to be $979,600, 
or $6,200 per airplane.
    The total cost impact figures discussed above are based on 

[[Page 53887]]
    assumptions that no operator has yet accomplished any of the current or 
proposed requirements of this AD action, and that no operator would 
accomplish those actions in the future if this AD were not adopted.

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), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9152 (60 FR 
9616, February 21, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

Aerospatiale: Docket 95-NM-146-AD. Supersedes AD 95-02-51, Amendment 
39-9152.

    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 in 
icing conditions, as defined in the Airplane Flight Manual (AFM), 
accomplish the following:
    (a) For all airplanes: Except as provided in paragraphs (b) and 
(c) of this AD, within 24 hours after receipt of telegraphic AD T94-
25-51, incorporate the following information into the Limitations 
Section of the FAA-approved AFM. This may be accomplished by 
inserting a copy of this AD in the AFM.
    ``(1) Operation of the airplane into forecast or reported icing 
conditions, as such conditions are defined in the AFM, is 
prohibited.
    ``(2) Use of the autopilot is prohibited during inadvertent 
flight in icing conditions, as defined in the AFM, or when the 
airplane is operated in moderate or greater turbulence.
    ``(3) If any unusual lateral trim situations are observed, such 
as excessive trim displacement; illumination of the message `RETRIM 
ROLL R WING DN' or `RETRIM ROLL L WING DN' on the advisory display 
unit (ADU); illumination of the message `AILERON MISTRIM' on the 
ADU; or abnormal flight characteristics of the airplane: Disconnect 
the autopilot and manually fly the airplane prior to adjusting the 
lateral trim. The autopilot may be re-engaged following manual 
adjustment of the lateral trim.''
    (b) For Model ATR-42 series airplanes: Within 6 months after the 
effective date of this AD, accomplish the requirements of paragraph 
(b)(1), (b)(2), (b)(3), and (b)(4) of this AD. Accomplishment of the 
requirements of this paragraph constitutes terminating action for 
the requirements of paragraph (a) of this AD.
    (1) Modify the deicing boots on the leading edges of the wing by 
accomplishing Aerospatiale Modification 4216 (during retrofit) or 
4222 (during production) in accordance with Aerospatiale Service 
Bulletin ATR42-30-0059, Revision 1, dated April 10, 1995.
    (2) Insert ATR-42 AFM Temporary Revision 20, dated May 1995, 
into the Limitations Section of the FAA-approved AFM. Once inserted, 
the AFM revision required by AD 95-02-51 may be removed from the 
AFM.

    Note 2: This may be accomplished by inserting copies of 
Temporary Revision 20 in the AFM. When these temporary revisions 
have been incorporated into general revisions of the AFM, the 
general revisions may be inserted in the AFM, provided the 
information contained in the general revisions is identical to that 
specified in Temporary Revision 20.

    (3) Establish an FAA-approved system to provide forecasts and 
reports of freezing rain and freezing drizzle at enroute altitudes 
along the route of flight and at all airports considered in the 
flight planning process. Training concerning the use of these icing 
forecasts and reports shall be accomplished at intervals not to 
exceed one year in accordance with Flight Standards Information 
Bulletin ``ATR-42 and ATR-72 Airworthiness Directive T95-02-51 
Compliance Procedures,'' dated January 11, 1995.

    Note 3: Training conducted previously in compliance with the 
requirements of AD 95-02-51, amendment 39-9152, may serve as initial 
training for purposes of computing the training interval.

    (4) Prior to flight in known or forecast icing conditions, and 
thereafter at intervals not to exceed one year, conduct flight crew 
training based on the revised ATR Icing Procedures Brochure 
``Freezing Drizzle: Towards a Better Knowledge and a Better 
Protection,'' Issue 1, dated May 11, 1995.

    Note 4: Training conducted previously in compliance with the 
requirements of AD 95-02-51, amendment 39-9152, may serve as initial 
training for purposes of computing the training interval.

    (c) For Model ATR-72 series airplanes: Within 6 months after the 
effective date of this AD, accomplish the requirements of paragraph 
(c)(1), (c)(2), (c)(3), (c)(4), and (c)(5) of this AD. 
Accomplishment of the requirements of this paragraph constitutes 
terminating action for the requirements of paragraph (a) of this AD.
    (1) Modify the deicing boots on the leading edges of the wing by 
accomplishing Aerospatiale Modification 4215 (during retrofit) or 
4221 (during production) in accordance with Aerospatiale Service 
Bulletin ATR72-30-1023, Revision 1, dated April 10, 1995.
    (2) Install Aerospatiale Modification 4213, ``Flaps Extension 
Inhibition Above VFE 15 deg.,'' in accordance with Aerospatiale 
Service Bulletin ATR72-27-1039, dated January 12, 1995.
    (3) Insert ATR-72 AFM Temporary Revision 16, dated May 1995, 
into the Limitations Section of the FAA-approved AFM. Once inserted, 
the AFM revision required by AD 95-02-51 may be removed from the 
AFM.

    Note 5: This may be accomplished by inserting copies of 
Temporary Revision 16 in the AFM. When these temporary revisions 
have been incorporated into general revisions of the AFM, the 
general revisions may be inserted in the AFM, provided the 

[[Page 53888]]
information contained in the general revisions is identical to that 
specified in Temporary Revision 16.
    (4) Establish an FAA-approved system to provide forecasts and 
reports of freezing rain and freezing drizzle at enroute altitudes 
along the route of flight and at all airports considered in the 
flight planning process. Training concerning the use of these icing 
forecasts and reports shall be accomplished at intervals not to 
exceed one year in accordance with Flight Standards Information 
Bulletin ``ATR-42 and ATR-72 Airworthiness Directive T95-02-51 
Compliance Procedures,'' dated January 11, 1995.

    Note 6: Training conducted previously in compliance with the 
requirements of AD 95-02-51, amendment 39-9152, may serve as initial 
training for purposes of computing the training interval.

    (5) Prior to flight in known or forecast icing conditions, and 
thereafter at intervals not to exceed one year, conduct flight crew 
training based on the revised ATR Icing Procedures Brochure 
``Freezing Drizzle: Towards a Better Knowledge and a Better 
Protection,'' Issue 1, dated May 11, 1995.

    Note 7: Training conducted previously in compliance with the 
requirements of AD 95-02-51, amendment 39-9152, may serve as initial 
training for purposes of computing the training interval.

    (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 8: 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 October 12, 1995.
S. R. Miller,
 Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-25836 Filed 10-17-95; 8:45 am]
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