[Federal Register Volume 63, Number 84 (Friday, May 1, 1998)]
[Proposed Rules]
[Pages 24136-24138]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-11561]


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 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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  Federal Register / Vol. 63, No. 84 / Friday, May 1, 1998 / Proposed 
Rules  

[[Page 24136]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-113-AD]
RIN 2120-AA64


Airworthiness Directives; British Aerospace BAe Model ATP 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain British Aerospace BAe 
Model ATP airplanes. This proposal would require repetitive inspections 
for discrepancies of the spring strut assembly of the forward door of 
the main landing gear (MLG), and replacement of the existing spring 
strut assembly with a new or serviceable part, if necessary. This 
proposal also would require eventual replacement of the existing spring 
strut assembly with an improved part, which, when accomplished, would 
terminate the repetitive inspections. This proposal is prompted by 
issuance of mandatory continuing airworthiness information by a foreign 
civil airworthiness authority. The actions specified by the proposed AD 
are intended to prevent failure of the spring strut assembly of the 
forward door of the MLG, which, if not corrected, could result in 
inability to extend the MLG.

DATES: Comments must be received by June 1, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-113-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 AI(R) American Support, Inc., 13850 Mclearen Road, 
Herndon, Virginia 20171. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

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:

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 98-NM-113-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-114, Attention: Rules 
Docket No. 98-NM-113-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, notified the FAA that an unsafe 
condition may exist on certain British Aerospace BAe Model ATP 
airplanes. The CAA advises that a BAe Model ATP airplane made an 
emergency landing because the left main landing gear (MLG) failed to 
extend. Investigation of the incident revealed a number of possible 
causes, including corrosion, wear, or damage to the operating 
mechanism. On March 31, 1998, the FAA issued a notice of proposed 
rulemaking (NPRM) to address these possible causes (reference Docket 
No. 97-NM-312-AD; 63 FR 16713, April 6, 1998).
    Further investigation of the incident revealed that the spring 
strut assembly of the forward door of the MLG on the airplane was 
loose. (The spring strut assembly is part of the mechanism which opens 
the MLG door and allows extension and retraction of the MLG.) Similar 
loose attachment also was observed on one other in-service airplane, 
and has been attributed to damage of the rivets that connect the fork 
end of the spring strut assembly to the tube of the assembly. Failure 
of these rivets, if not corrected, could cause failure of the spring 
strut assembly of the forward door of the MLG, which could result in 
inability to extend the MLG.

Explanation of Relevant Service Information

    The manufacturer has issued British Aerospace Alert Service 
Bulletin ATP-32-85, Revision 1, dated March 20, 1998, which describes 
procedures for repetitive visual inspections for discrepancies of the 
fork end of the spring strut assembly of the forward door of the left 
and right MLG on the airplane. The actions involve inspecting for 
looseness or damage of the rivets that connect the fork end fitting to 
the tube of the spring strut assembly, and inspecting for movement 
between the fork end fitting and the tube of the spring strut assembly. 
This alert service bulletin also describes procedures for replacing the 
spring strut assembly with a new or serviceable part, if any rivet is 
found to be damaged, if any rivet hole is found to be elongated, or if 
the

[[Page 24137]]

attachment of the fork end fitting to the tube is found to be loose. 
The CAA classified this alert service bulletin as mandatory in order to 
assure the continued airworthiness of these airplanes in the United 
Kingdom.
    The manufacturer also has issued British Aerospace Service Bulletin 
ATP-32-87, dated January 29, 1998, which describes procedures for 
replacing the existing spring strut assembly of the forward door of the 
MLG with an improved spring strut assembly. Such replacement eliminates 
the need for the repetitive inspections described previously.
    Accomplishment of the actions specified in the service bulletins is 
intended to adequately address the identified unsafe condition.

FAA's Conclusions

    This airplane model is manufactured in the United Kingdom 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. Pursuant 
to this bilateral airworthiness agreement, the CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the CAA, reviewed all available information, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

    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 proposed AD would require accomplishment of 
actions specified in the service bulletins described previously, except 
as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that this AD proposes to mandate the 
replacement of the existing spring strut assembly of the forward door 
of the MLG with an improved spring strut assembly, as described in 
British Aerospace Service Bulletin ATP-32-87, dated January 29, 1998, 
as terminating action for the repetitive inspections specified in 
British Aerospace Alert Service Bulletin ATP-32-85, Revision 1, dated 
March 20, 1998. Accomplishment of the modification specified in this 
service bulletin has not been classified as mandatory by the CAA.
    The FAA has determined that, in certain cases, long-term continued 
operational safety will be better assured by design changes to remove 
the source of the problem, rather than by repetitive inspections. Long-
term inspections may not be providing the degree of safety assurance 
necessary for the transport airplane fleet. This, coupled with a better 
understanding of the human factors associated with numerous continual 
inspections, has led the FAA to consider placing less emphasis on 
inspections and more emphasis on design improvements. The proposed 
requirement to replace the existing spring strut assembly with an 
improved spring strut assembly is in consonance with these conditions.

Cost Impact

    The FAA estimates that 10 airplanes of U.S. registry would be 
affected by this proposed AD.
    It would take approximately 4 work hours (2 work hours per MLG) to 
accomplish the proposed inspection, at an average labor rate of $60 per 
work hour. Based on this figure, the cost impact of the inspection 
proposed by this AD on U.S. operators is estimated to be $2,400, or 
$240 per airplane, per inspection cycle.
    It would take approximately 12 work hours (6 work hours per MLG) to 
accomplish the proposed modification, at an average labor rate of $60 
per work hour. Required parts would cost approximately $2,200 per 
airplane ($1,100 per MLG). Based on this figure, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
$29,200, or $2,920 per airplane.
    The cost impact figures discussed above are 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.

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 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

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

British Aerospace Regional Aircraft (Formerly Jetstream Aircraft 
Limited; British Aerospace (Commercial Aircraft) Limited): Docket 
98-NM-113-AD.

    Applicability: BAe Model ATP airplanes, as listed in British 
Aerospace Alert Service Bulletin ATP-32-85, Revision 1, dated March 
20, 1998, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c) 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 prevent failure of the spring strut assembly of the forward 
door of the main landing gear (MLG), which, if not corrected, could 
result in the inability to extend the MLG, accomplish the following:
    (a) Within 600 flight hours after the effective date of this AD, 
perform a visual

[[Page 24138]]

inspection for discrepancies of the fork end of the spring strut 
assembly of the forward door of the MLG, on the left and right side 
of the airplane; in accordance with British Aerospace Alert Service 
Bulletin ATP-32-85, Revision 1, dated March 20, 1998.
    (1) If no discrepancy is detected, repeat the visual inspection 
thereafter at intervals not to exceed 1,500 flight hours until the 
actions specified by paragraph (b) of this AD are accomplished.
    (2) If any discrepancy is detected, prior to further flight, 
replace the existing spring strut assembly with a new or serviceable 
part, in accordance with the alert service bulletin. Repeat the 
visual inspection thereafter at intervals not to exceed 1,500 flight 
hours until the actions specified by paragraph (b) of this AD are 
accomplished.
    (b) Within 18 months after the effective date of this AD, 
replace the spring strut assembly of the forward door of the MLG 
with an improved spring strut assembly, on the left and right side 
of the airplane; in accordance with British Aerospace Service 
Bulletin ATP-32-87, dated January 29, 1998. This replacement 
constitutes terminating action for the requirements of this AD.
    (c) 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 request 
through an appropriate FAA Principal Maintenance Inspector, who may 
add comments and then send it to the Manager, International Branch, 
ANM-116.
    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the International Branch, ANM-116.

    (d) 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 April 24, 1998.
Gary L. Killion,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-11561 Filed 4-30-98; 8:45 am]
BILLING CODE 4910-13-P