[Federal Register Volume 61, Number 35 (Wednesday, February 21, 1996)]
[Rules and Regulations]
[Pages 6501-6503]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-3150]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-155-AD; Amendment 39-9514; AD 96-04-03]


Airworthiness Directives; Boeing Model 737-200 and -200C 
Airplanes Equipped With dB Partners Hush Kits Installed in Accordance 
With Supplemental Type Certificate (STC) SA5730NM

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 737-200 and -200C airplanes, 
that currently requires installation of fail-safe straps onto the 
engine inlet attach ring of the nose cowl. This amendment requires 
repetitive inspections to detect cracking of the attach ring of the 
nose cowl, and replacement of cracked attach rings. Replacement with an 
improved attach ring, if accomplished, would terminate the requirement 
to inspect the attach ring repetitively. This amendment is prompted by 
the development of an improved attach ring that eliminates the need for 
repetitive inspections. The actions specified by this AD are intended 
to prevent cracking of the attach ring of the nose cowl, which could 
result in separation of the nose cowl from the engine following failure 
of a turbine blade.

DATES: Effective March 22, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 22, 1996.
    The incorporation by reference of Nordam Service Bulletin SB 71-03, 
dated March 17, 1995, as listed in the regulations, was approved 
previously by the Director of the Federal Register as of May 2, 1995 
(60 FR 19157, April 17, 1995).

ADDRESSES: The service information referenced in this AD may be 
obtained from The Nordam Group, 624 East 4th Street, Tulsa, Oklahoma 
74120. 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: Thomas Rodriguez, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington; telephone (206) 227-2779; fax 
(206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 95-08-08, 
amendment 39-9197 (60 FR 19157, April 17, 1995), which is applicable to 
certain Boeing Model 737-200 and -200C airplanes, was published in the 
Federal Register on November 22, 1995 (60 FR 57840). The action 
proposed to supersede AD 95-08-08 to continue to require installation 
of fail-safe straps onto the engine inlet attach ring of the nose cowl. 
The action also proposed to require repetitive inspections to detect 
cracking of the attach ring of the nose cowl, and replacement of 
cracked attach rings. That action also proposed to provide an optional 
terminating action 

[[Page 6502]]
(installation of an improved attach ring) for the repetitive 
inspections.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the two comments received.
    Both commenters support the proposed rule.
    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 as proposed.
    There are approximately 46 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 1 
airplane of U.S. registry will be affected by this AD.
    The replacement action that is currently required by AD 95-08-08 
takes approximately 8 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Required parts will be 
provided at no cost to the operator. Based on these figures, the cost 
impact of the currently required actions on the sole U.S. operator is 
estimated to be $480 per airplane.
    The inspection that is required by this new AD will take 
approximately 10 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact on U.S. operators of the new requirements of this AD is 
estimated to be $600 per airplane, per inspection cycle.
    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 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 removing amendment 39-9197 (60 FR 
19157, April 17, 1995), and by adding a new airworthiness directive 
(AD), amendment 39-9514, to read as follows:

96-03-04 Boeing: Amendment 39-9514. Docket 95-NM-155-AD. Supersedes 
AD 95-08-08, Amendment 39-9197.

    Applicability: Model 737-200 and -200C airplanes equipped with 
dB Partners Hush Kit having attach ring, part number 65ND-54301-1, 
installed in accordance with Supplemental Type Certificate (STC) 
SA5730NM, 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 (e) 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 separation of the nose cowl from the engine following 
turbine blade failure, accomplish the following:
    (a) Within 30 days after May 2, 1995 (the effective date of AD 
95-08-08, amendment 39-9197), install fail-safe straps onto the 
attach ring, part number (P/N) 65ND-54301-1, of the nose cowl in 
accordance with Nordam Service Bulletin SB 71-03, dated March 17, 
1995, or Revision 1, dated June 16, 1995.
    (b) As of the effective date of this AD: Prior to further flight 
following each incident of turbine blade failure, perform a detailed 
visual inspection to detect cracking of the attach ring of the nose 
cowl. Fail-safe straps must be removed to perform this inspection.
    (1) If no cracking is detected, prior to further flight, 
reinstall the fail-safe straps in accordance with Nordam Service 
Bulletin SB 71-03, dated March 17, 1995, or Revision 1 dated June 
16, 1995.
    (2) If any cracking is detected, prior to further flight, 
accomplish the requirements of either paragraph (b)(2)(i) or 
(b)(2)(ii) of this AD.
    (i) Replace the cracked attach ring with an attach ring having 
P/N 65ND-54301-1 in accordance with STC SA5730NM, and reinstall the 
fail-safe strap in accordance with Nordam Service Bulletin SB 71-03, 
dated March 17, 1995, or Revision 1, dated June 16, 1995. Repeat the 
visual inspection of the attach ring prior to further flight 
following each incident of turbine blade failure. Or
    (ii) Replace the cracked attach ring with an attach ring having 
P/N 65ND-54301-5 in accordance with Nordam Service Bulletin SB 71-
04, Revision 1, dated June 16, 1995. After this replacement is 
accomplished, the inspections required by this paragraph may be 
terminated.
    (c) Installation of an attach ring having P/N 65ND-54301-5 
constitutes terminating action for the repetitive inspections 
required by paragraph (b) of this AD.
    (d) As of May 2, 1995 (the effective date of AD 95-08-08), fail-
safe straps must be installed onto the attach ring, P/N 65ND-54301-
1, of the nose cowl in accordance with Nordam Service Bulletin SB 
71-03, dated March 17, 1995, or Revision 1, dated June 16, 1995, 
prior to installation of STC SA5730NM on any airplane.
    (e) 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, Seattle Aircraft Certification 
Office (ACO), 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, Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (f) 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.
    (g) The actions shall be done in accordance with the following 
Nordam service bulletins, as applicable, which contain the specified 
effective pages: 

[[Page 6503]]


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                                                       Revision level shown on                                  
  Service bulletin reference and date      Page No.              page                   Date shown on page      
----------------------------------------------------------------------------------------------------------------
SB 71-03, March 17, 1995...............         1-12  Original.................  March 17, 1995.                
SB 71-03, Revision 1, June 16, 1995....         1-11  1........................  June 16, 1995.                 
                                                  12  Original.................  March 17, 1995.                
SB 71-04, Revision 1, June 16, 1995....         1, 2  Original.................  May 22, 1995.                  
                                                3-18  1........................  June 16, 1995.                 
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    The incorporation by reference of Nordam Service Bulletin SB 71-
03, dated March 17, 1995, was approved previously by the Director of 
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51 as of May 2, 1995 (60 FR 19157, April 17, 1995). The 
incorporation by reference of the remainder of the service documents 
listed above is approved 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 The Nordam Group, 624 East 4th Street, 
Tulsa, Oklahoma 74120. 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.
    (h) This amendment becomes effective on March 22, 1996.

    Issued in Renton, Washington, on February 7, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-3150 Filed 2-20-96; 8:45 am]
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