[Federal Register Volume 65, Number 175 (Friday, September 8, 2000)]
[Rules and Regulations]
[Pages 54403-54407]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-22908]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-183-AD; Amendment 39-11890; AD 2000-18-05]
RIN 2120-AA64


Airworthiness Directives; Aerospatiale Model ATR42 and ATR72 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all Aerospatiale Model ATR42 and ATR72 series airplanes, 
that requires modification of the alerting capability of the anti-icing 
advisory system to improve crew awareness of icing conditions, 
replacement of the median wing de-icing boots with extended de-icing 
boots, and installation of de-icing boots on the metallic wing leading 
edge. This amendment is prompted by issuance of mandatory continuing 
airworthiness information by a foreign civil airworthiness authority. 
The actions specified by this AD are intended to reduce the degradation 
of lift and drag characteristics in prolonged severe icing exposure, 
which could result in loss of lift and consequent reduced 
controllability of the airplane.

DATES: Effective October 13, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 13, 2000.

ADDRESSES: The service information referenced in this AD may be 
obtained from Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 
03, France. This information may be examined at the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, Rules Docket, 
1601 Lind Avenue, SW., Renton, Washington; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2110; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD)

[[Page 54404]]

that is applicable to certain Aerospatiale Model ATR42 and ATR72 series 
airplanes was published in the Federal Register on October 27, 1999 (64 
FR 57787). That action proposed to require modification of the alerting 
capability of the anti-icing advisory system to improve flight crew 
awareness of icing conditions, replacement of the median wing de-icing 
boots with extended de-icing boots, and installation of de-icing boots 
on the metallic wing leading edge.

Explanation of Relevant Service Information

    Aerospatiale has issued Revision 2 of the following Avions de 
Transport Regional Service Bulletins:

------------------------------------------------------------------------
        Service bulletin                   Date                Model
------------------------------------------------------------------------
ATR42-30-0064..................  October 1, 1999........  ATR42
ATR42-30-0063..................  October 1, 1999........  ATR42
ATR42-30-0065..................  October 25, 1999.......  ATR42
ATR72-30-1032..................  October 1, 1999........  ATR72
ATR72-30-1033..................  October 1, 1999........  ATR72
ATR72-30-1034..................  October 19, 1999.......  ATR72
------------------------------------------------------------------------

The service bulletins that were cited in the proposed AD as the 
appropriate sources of service information were all at Revision 1. The 
procedures described in Revisions 1 and 2 are essentially the same; 
Revision 2 was issued to correct certain technical errors. 
Accomplishment of the actions specified in Revision 2 of the service 
bulletins is intended to adequately address the identified unsafe 
condition.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Modification Requirement

    One commenter agrees that the modifications specified in the 
proposed AD ``represent a step forward in providing a higher level of 
protection for an aircraft operating in icing conditions or with 
airframe ice accretions.''
    Request To Revise Intent of AD
    Two commenters request that certain language of the proposed AD be 
revised to more accurately explain the scope and purpose of the 
proposed actions.
    1. One commenter requests that the proposed AD be revised to 
indicate that the proposed modifications represent only improvements 
over the present system, not a solution to the degradation of lift and 
drag in prolonged exposures to severe icing.
    2. This same commenter requests a revision of certain portions of 
the proposed AD that state that the proposed modifications are intended 
to ``prevent degradation of lift and drag characteristics in prolonged 
severe icing exposure, which could result in loss of lift and 
consequent reduced controllability of the airplane.'' The commenter 
notes that, ``if degradations in lift and drag are being prevented, the 
aircraft is not in severe icing.''
    3. Another commenter requests that the proposed AD be revised to 
reflect that the actions are intended to ``prevent degradation of lift 
and drag characteristics in prolonged severe icing exposure, which 
could result in wing stall.''
    4. This same commenter disagrees with certain statements in the 
Discussion section of the proposed AD, and proposes the following 
revision:

    ``The DGAC advises that the existing median wing de-icing boots 
may not be adequate to protect the airplane during prolonged 
exposure to severe icing conditions, outside of those for which the 
airplane has been certificated. Such prolonged exposure could 
produce degradation of lift and drag characteristics which could 
result in wing stall.
    In addition, DGAC reports that in several instances, crews have 
failed to activate the de-icing boots, despite the fact that ice 
accretion had been detected by the Anti-icing Advisory System (AAS). 
This failure could indicate that the current design of the AAS may 
not provide adequate alerting signal to the flight crew in case of 
lack of awareness or vigilance.''

The commenter requests this revision of the Discussion section for the 
following reasons:

     The commenter states that, ``[p]riority should be given to 
the median de-icing boot extension to further enhance the airplane's 
robustness in case of prolonged severe icing encounters.'' [The FAA 
infers that the commenter objects to the order in which the issues were 
presented in the proposed AD (the icing light logic problem was 
discussed before the boot modification), although the issues were 
presented in no particular order.]
     The modification of the ICING light flashing logic should 
be considered only a reinforcement of crew awareness and vigilance, 
considering the importance of human factors during flight in severe 
icing conditions.
     The proposed AD states that failure to activate the boots 
may indicate that the AAS may not provide adequate alerting ``in all 
instances of ice accretion.'' The commenter suggests that this could be 
interpreted to mean that the AAS system could malfunction under some 
ice accretion conditions. The commenter points out that the AAS 
modification addresses only its warning logic, not its detection 
capability.
     In line with its policy to avoid relying only on 
procedures to address safety issues, the DGAC mandated the 
modifications proposed in the NPRM.

FAA's Response: Clarification of Intent

    In response to these comments, the FAA agrees that clarification of 
the intent of the AD may be necessary. The actions proposed by this AD 
are intended to enhance the alerting capability and performance of the 
airplane ice protection system. Accomplishment of these actions will 
result in a more robust icing protection system that will provide an 
increased level of safety during flight in icing conditions.
    It was not the FAA's intent to suggest that the new de-icing boots 
proposed by this AD would provide a permanent solution for prolonged 
flight in severe icing conditions. The new de-icing boots are not FAA-
approved for operation in severe icing, although they represent product 
improvements that may provide some benefit during an inadvertent 
encounter with a severe icing environment. The FAA Aeronautical 
Information Manual defines ``severe icing'' as follows:

    ``The rate of [ice] accumulation is such that the de-icing/anti-
icing equipment fails to reduce or control the hazard. Immediate 
flight diversion is necessary.''

It is therefore clear that no airplane is approved for operations in 
severe icing conditions, and, if such conditions are inadvertently 
encountered, an immediate diversion is the only practical means to deal 
with the hazard at this time. The FAA and the aviation industry are 
working to define a ``severe icing envelope,'' i.e., icing conditions

[[Page 54405]]

that may be outside the present certification envelope (as required by 
Appendix C of part 25 of the Federal Aviation Regulations). Until the 
FAA and the aviation industry agree on the definition of this new 
severe icing envelope and a means to operate safely within it, the FAA 
is not prepared to consider approval of operations in such conditions. 
Therefore, the final rule has been revised (in several places) to state 
that the required actions are intended to reduce (rather than 
``prevent'') the degradation of lift and drag characteristics in 
prolonged severe icing exposure, which could result in loss of lift and 
consequent reduced controllability of the airplane.
    The DGAC has advised the FAA of a few instances in which 
flightcrews failed to activate the de-icing boots, despite the fact 
that ice accretion had been detected by the AAS. As a result, the 
manufacturer has developed an enhancement of the alerting capability of 
the AAS system that reinforces flightcrew awareness of icing 
conditions. This modification results in the ICING light on the 
instrument panel continuing to flash as long as both level 2 and level 
3 ice protection systems are not selected, once ice accretion has been 
detected by the electronic ice detection system. [Note: Level 1 
(windshield heat and pitot-probe heat) is always on for every flight. 
Level 2 is the ``anti-icing'' mode (propeller and elevator/rudder horn 
heat, side window heat, and engine ice protection). Level 3 is the 
``de-icing'' mode (airframe de-icing boots activated), and is on when 
level 2 is still in effect.]
    In an effort to further enhance safety, the DGAC has also mandated 
a modification that extends the chord-wise coverage of the median wing 
boots. That mandate [French airworthiness directives 1999-165-077(B) 
(for Model ATR42 series airplanes) and 1999-166-041(B) (for Model ATR72 
series airplanes); both dated April 21, 1999] prompted the issuance of 
the proposed AD. The new boots extend farther back on both the upper 
and lower surfaces of the wing. These extended boots have not been 
shown to provide any measurable improvement in the airplane's ability 
to operate safely in severe icing conditions, and are not offered by 
Aerospatiale in order to gain any operational advantage in these severe 
conditions. However, if the flightcrew inadvertently encounters severe 
icing, these extended boots may increase the level of safety while the 
flightcrew takes the required steps to immediately exit the severe 
icing conditions.
    The FAA agrees that rewording the Discussion section of the 
proposed AD might clarify the purpose and anticipated benefit of the 
modifications; however, the Discussion section is not restated in a 
final rule.

Request To Revise Applicability

    One commenter requests that the applicability of the proposed AD be 
revised to exclude airplanes on which the proposed modifications have 
been accomplished.
    The FAA concurs. To better define the airplanes affected by this 
AD, the FAA has revised the applicability to exclude airplanes on which 
certain modifications have been accomplished.

Request To Require Revised Service Bulletins

    One commenter has identified certain minor technical errors in 
Revision 1 of the service bulletins that would ``prevent proper 
operation of the entire modification'' if accomplished strictly in 
accordance with the accomplishment instructions. (Revision 1 was cited 
in the proposed AD as the appropriate source of service information.) 
The commenter reports that it was advised by the manufacturer that 
those technical issues will be corrected in the next service bulletin 
revisions.
    The FAA partially concurs. Revision 2 of the service bulletins 
incorporates the corrected information. However, the manufacturer 
advises that clarification and correct instructions were provided so 
that the modification can be accomplished with the Revision 1 
instructions. The manufacturer further advises that no additional work 
should be necessary for an airplane modified in accordance with 
Revision 1. Therefore, the final rule has been revised to require 
accomplishment of the modification in accordance with Revision 2, and 
to include a note that credits operators for prior accomplishment in 
accordance with Revision 1.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    The FAA estimates that 140 airplanes of U.S. registry will be 
affected by this AD.
    The replacement of existing de-icing boots and the new installation 
of de-icing boots will take approximately 75 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts will cost approximately $5,500 per airplane. Based on these 
figures, the cost impact of the replacement/installation required by 
this AD on U.S. operators is estimated to be $1,400,000, or $10,000 per 
airplane.
    The modification of the alerting capability of the Anti-icing 
Advisory System (AAS) will take approximately 30 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Required parts will cost approximately $2,000 per airplane. Based on 
these figures, the cost impact of the modification required by this AD 
on U.S. operators is estimated to be $532,000, or $3,800 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

[[Page 54406]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

2000-18-05  Aerospatiale: Amendment 39-11890. Docket 99-NM-183-AD.

    Applicability: The following airplanes, certificated in any 
category:
--Model ATR42 series airplanes, excluding those modified in 
accordance with Aerospatiale Matra ATR Modifications 4993, 4998, and 
5008
--Model ATR72 series airplanes, excluding those modified in 
accordance with Aerospatiale Matra ATR Modifications 4994, 4997, and 
5008

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (d) 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 reduce the degradation of lift and drag characteristics in 
prolonged severe icing exposure, which could result in loss of lift 
and consequent reduced controllability of the airplane, accomplish 
the following:

Boot Replacement/Installation

    (a) Within 30 months after the effective date of this AD, 
replace the median wing de-icing boots with extended de-icing boots 
in accordance with Avions de Transport Regional Service Bulletin 
ATR42-30-0063, Revision 2, dated October 1, 1999 (for Model ATR42 
series airplanes), or ATR72-30-1032, Revision 2, dated October 1, 
1999 (for Model ATR72 series airplanes); as applicable.
    (b) Within 30 months after the effective date of this AD, 
install de-icing boots on the metallic wing leading edge in 
accordance with Avions de Transport Regional Service Bulletin ATR42-
30-0064, Revision 2, dated October 1, 1999 (for Model ATR42 series 
airplanes), or ATR72-30-1033, Revision 2, dated October 1, 1999 (for 
Model ATR72 series airplanes); as applicable.

Modification

    (c) Within 30 months after the effective date of this AD, modify 
the ICING light flashing logic of the Anti-icing Advisory System 
(AAS), in accordance with Avions de Transport Regional Service 
Bulletin ATR42-30-0065, Revision 2, dated October 25, 1999 (for 
Model ATR42 series airplanes), or Avions de Transport Regional 
Service Bulletin ATR72-30-1034, Revision 2, dated October 19, 1999 
(for Model ATR72 series airplanes); as applicable.

    Note 2: Accomplishment of the boot replacement, boot 
installation, and modification is also considered acceptable for 
compliance with the applicable requirements of paragraphs (a), (b), 
and (c) of this AD, if accomplished in accordance with Revision 1 of 
the following Avions de Transport Regional service bulletins: (For 
Model ATR42 Series Airplanes) ATR42-30-0063, May 7, 1999, ATR42-30-
0064, May 7, 1999, ATR42-30-0065, May 17, 1999 (For Model ATR72 
Series Airplanes) ATR72-30-1032, May 7, 1999, ATR72-30-1033, May 7, 
1999, ATR72-30-1034, May 17, 1999.

Alternative Methods of Compliance

    (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, International Branch, ANM-116, FAA, 
Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Maintenance Inspector, 
who may add comments and then send it to the Manager, International 
Branch, ANM-116.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

Special Flight Permits

    (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.

Incorporation by Reference

    (f) The actions shall be done in accordance with the following 
Avions de Transport Regional Service Bulletins, as applicable:

----------------------------------------------------------------------------------------------------------------
                                                                Revision level
      Service bulletin and date              Page numbers        shown on the          Date shown on page
                                                                     page
----------------------------------------------------------------------------------------------------------------
ATR72-30-1032, Revision 2, October 1,  1-10, 14-16, 33, 34, 43               2  October 1, 1999.
 1999.
                                       11-13, 17-32, 35-42,                  1  May 7, 1999.
                                        44, 45.
ATR72-30-1033, Revision 2, October 1,  1, 2, 6, 7, 8, 15......               2  October 1, 1999.
 1999.
                                       3-5, 9-14, 16-43.......               1  May 7, 1999.
ATR72-30-1034, Revision 2, October     1, 2, 4, 8-31..........               2  October 19, 1999.
 19, 1999.
                                       3......................               1  May 17, 1999.
                                       5, 6, 7................           (\1\)  February 2, 1999.
ATR42-30-0063, Revision 2, October 1,  1-5, 9, 10, 13, 14, 16,               2  October 1, 1999.
 1999.                                  18, 19, 37, 38, 43, 47.
                                       6-8, 11, 12, 15, 17, 20-              1  May 7, 1999.
                                        36, 39-42, 44-46, 48,
                                        49.
ATR42-30-0064, Revision 2, October 1,  1-5, 8-10, 12-14, 20,                 2  October 1, 1999.
 1999.                                  21, 35-54, 59, 60.
                                       6, 7, 11, 15-19, 22-34,               1  May 7, 1999.
                                        55-58, 61.
ATR42-30-0065, Revision 2, October     1-5, 7-52..............               2  October 25, 1999.
 25, 1999.
                                       6......................               1  May 17, 1999.
----------------------------------------------------------------------------------------------------------------
\1\ Original.

This incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Aerospatiale, 316 Route de Bayonne, 
31060 Toulouse, Cedex 03, France. Copies may be inspected at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.

    Note 4: The subject of this AD is addressed in French 
airworthiness directives 1999-165-077(B) and 1999-166-041(B), both 
dated April 21, 1999.

    (g) This amendment becomes effective on October 13, 2000.


[[Page 54407]]


    Issued in Renton, Washington, on August 31, 2000.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-22908 Filed 9-7-00; 8:45 am]
BILLING CODE 4910-13-P