AD Amdt-39-10659

[Federal Register Volume 63, Number 136 (Thursday, July 16, 1998)]
[Rules and Regulations]
[Pages 38289-38290]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 98-18770]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-02-AD; Amendment 39-10659; AD 98-15-08]
RIN 2120-AA64


Airworthiness Directives; British Aerospace Model BAe 146 and 
Model Avro 146-RJ 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 certain British Aerospace Model BAe 146 and Model Avro 
146-RJ series airplanes, that requires repetitive detailed visual 
inspections of the top wing skins for stress corrosion cracks, damage, 
or missing surface protective finish of the metallic surfaces; and 
repair, if necessary. This amendment is prompted by reports of stress 
corrosion cracks found on the top wing skin during routine inspection 
on three airplanes. The actions specified by this AD are intended to 
detect and correct such cracking, which could result in reduced 
structural integrity of the wing.

DATES: Effective August 20, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 20, 1998.

ADDRESSES: The service information referenced in this AD 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; 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) that is applicable to certain British Aerospace Model 
BAe 146 and Model Avro 146-RJ series airplanes was published in the 
Federal Register on June 17, 1997 (62 FR 32701). That action proposed 
to require repetitive detailed visual inspections of the top wing skins 
for stress corrosion cracks, damage, or missing surface protective 
finish of the metallic surfaces, and repair, if necessary.

Consideration of Comments

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

Components Made of 7150-T651 Aluminum Material

    The commenter supports the proposed AD. However, the commenter 
expresses a concern that other airplane components made from the same 
material could pose a similar problem. As a result, the commenter 
requests the FAA to accomplish the following actions:

--Identify any other aircraft components made from the same material.
--Review the inspection criteria and frequency for those applications.
--Ensure that a failure of the material will be detected prior to the 
failure posing a risk to continued flight safety.

    The FAA acknowledges the concerns of the commenter. Based on 
additional information from the manufacturer, the FAA has determined 
that the problem is limited to a discrepant production lot of 7150-T651 
aluminum material that was produced with the incorrect thickness for 
the wing skins. In addition, the FAA has determined that no other 
components made of this aluminum material are affected. In light of 
this information, the FAA finds that it is unnecessary to take any 
additional action, and that the actions required by this AD are 
adequate in order to ensure the continued safety of the fleet.

Explanation of New Service Information

    Since the issuance of the proposed AD, the manufacturer issued 
British Aerospace Service Bulletin SB.57-49, Revision 1, dated June 19, 
1997, which replaces British Aerospace Service Bulletin SB.57-49, dated 
June 4, 1996. Revision 1 reduces the effectivity specified in the 
previous service bulletin to those airplanes on which 7150-T651 
aluminum material from a discrepant production lot was used for the top 
wing skins. The discrepant material was manufactured with an 
inappropriate thickness, which causes the wings to be susceptible to 
early stress corrosion cracking on the top wing skin, and which could 
result in reduced structural integrity of the airplane wing. However, 
since the discovery of this problem, subsequent 7150-T651 aluminum 
material used for the top wing skins has been machined to the 
appropriate thickness and, as a result, is not susceptible to early 
stress corrosion cracking. In all other respects, Revision 1 of the 
service bulletin is essentially the same as the original issue of the 
service bulletin.
    The FAA has reduced the applicability of this final rule to those 
airplanes having wing skins made from 7150-T651 aluminum material, as 
specified in British Aerospace Service Bulletin SB.57-49, Revision 1, 
dated June 19, 1997. In addition, the FAA has revised paragraph (a) of 
the final rule to require accomplishment of those actions in accordance 
with either the original service bulletin or Revision 1.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air

[[Page 38290]]

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 12 British Aerospace Model BAe 146 and Model 
Avro 146-RJ series airplanes of U.S. registry will be affected by this 
AD, that it will take approximately 4 work hours per airplane to 
accomplish the required actions, and that the average labor rate is $60 
per work hour. Based on these figures, the cost impact of the AD on 
U.S. operators is estimated to be $2,880, or $240 per airplane.
    The cost impact figure discussed above is 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.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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.

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:

98-15-08  British Aerospace Regional Aircraft (Formerly British 
Aerospace Regional Aircraft Limited, Avro International Aerospace 
Division; British Aerospace, PLC; British Aerospace Commercial 
Aircraft Limited): Amendment 39-10659. Docket 97-NM-02-AD.

    Applicability: Model BAe 146 and Model Avro 146-RJ series 
airplanes, as listed in British Aerospace Service Bulletin SB.57-49, 
Revision 1, dated June 19, 1997, and having wing skins made from 
7150-T651 aluminum; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.
    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct stress corrosion cracking in the wing 
skin, which could result in reduced structural integrity of the 
wing, accomplish the following:
    (a) Within 4 months after the effective date of this AD; and 
thereafter at intervals not to exceed 4,000 landings or 2 years, 
whichever occurs first: Perform a detailed visual inspection of the 
top wing skins to detect stress corrosion cracking, and any damaged 
or missing surface protective finish that exposes the metallic 
surfaces, in accordance with British Aerospace Service Bulletin 
SB.57-49, dated June 4, 1996, or Revision 1, dated June 19, 1997.
    (1) If any damaged or missing surface protective finish is 
detected, and no cracking or corrosion is detected, prior to further 
flight, reapply the protective finish in accordance with the service 
bulletin. Repeat the detailed visual inspection, thereafter, at 
intervals not to exceed 4,000 landings or 2 years, whichever occurs 
first.
    (2) If any cracking is detected, prior to further flight, repair 
in accordance with a method approved by the Manager, International 
Branch, ANM-116, FAA, Transport Airplane Directorate.

    Note 2: During the detailed visual inspections of the top wing 
skins, pay particular attention to the edge of cutouts, skin edges, 
and attachment bolt holes.

    (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, International Branch, ANM-116. 
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.

    (c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (d) Except as provided by paragraph (a)(2) of this AD, the 
inspections and repairs shall be done in accordance with British 
Aerospace Service Bulletin SB.57-49, dated June 4, 1996; or British 
Aerospace Service Bulletin SB.57-49, Revision 1, dated June 19, 
1997. 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 AI(R) American Support, Inc., 
13850 Mclearen Road, Herndon, Virginia 20171. 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 British 
airworthiness directive 005-06-96, dated June 4, 1996.

    (e) This amendment becomes effective on August 20, 1998.

    Issued in Renton, Washington, on July 8, 1998.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-18770 Filed 7-15-98; 8:45 am]
BILLING CODE 4910-13-U