[Federal Register Volume 60, Number 225 (Wednesday, November 22, 1995)]
[Proposed Rules]
[Pages 57840-57842]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-28546]



 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 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.
 
 ========================================================================
 

  Federal Register / Vol. 60, No. 225 / Wednesday, November 22, 1995 / 
Proposed Rules  

[[Page 57840]]


DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-155-AD]


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: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of 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 
action would require repetitive inspections to detect cracking of the 
attach ring of the nose cowl, and replacement of cracked attach rings. 
Replacement with a certain attach ring, if accomplished, would 
terminate the requirement to inspect the attach ring repetitively. This 
proposal is prompted by the development of an improved attach ring. The 
actions specified by the proposed 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: Comments must be received by December 22, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-155-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 The Nordam Group, 624 East 4th Street, Tulsa, Oklahoma 
74120. This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue SW., Renton, Washington.

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:

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 95-NM-155-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-155-AD, 1601 Lind Avenue SW., Renton, Washington 
98055-4056.

Discussion

    On April 5, 1995, the FAA issued AD 95-08-08, amendment 39-9197 (60 
FR 19157, April 17, 1995), applicable to certain Boeing 737-200 and -
200C airplanes, to require installation of fail-safe straps onto the 
attach ring of the nose cowl. The part number of the subject attach 
ring on the affected airplanes is part number (P/N) 65ND-54301-1. That 
AD action was prompted by reports of failure of reworked turbine 
blades, and subsequent failure of the engine inlet attach ring. The 
requirements of that AD are intended to prevent separation of the nose 
cowl from the engine following turbine blade failure.
    In the preamble to AD 95-08-08, the FAA indicated that the actions 
required by that AD were considered ``interim action'' and that further 
rulemaking action was being considered. The FAA now has determined that 
further rulemaking action is indeed necessary, and this proposed AD 
follows from that determination.

Explanation of New Data

    Nordam, the manufacturer of these nose cowls, has recently 
developed an attach ring having P/N 65ND-54301-5, which is made of 
forging material that is stronger and more impact resistant than the 
attach ring having P/N 65ND-54301-1. Installation of this improved 
attach ring eliminates the need for the installation of fail-safe 
straps (as is required by AD 95-08-08).
    While the FAA considers that the improved attached ring will 
positively address the unsafe condition addressed by the existing AD, 
the FAA has a high degree of assurance that cracking of the attach ring 
having P/N 65ND-54301-1 will be detected prior to the nose cowl 
separating from the engine, provided visual inspections of the attach 
ring are performed following each incident of turbine blade failure. 
Operators using repetitive detailed visual inspection techniques should 
be able to detect cracking easily on that attach ring, which is easily 
accessible.

Explanation of Service Information

    The FAA has reviewed and approved Nordham Service Bulletin 71-04, 
Revision 1, dated June 16, 1995, which describes procedures for 
replacing the attach ring, P/N 65ND-54301-1, of the 

[[Page 57841]]
nose cowl with the improved attach ring, P/N 65ND-54301-5.
    The FAA also has reviewed and approved Nordham Service Bulletin 71-
03, Revision 1, dated June 16, 1995, which describes procedures for 
installing fail-safe straps onto the attach ring, part number (P/N) 
65ND-54301-1, of the nose cowl. The originally issued version of this 
service bulletin was referenced in AD 95-08-08 as the appropriate 
source of service information. Revision 1 is essentially identical to 
the originally issued version, but includes references to optional 
part-numbered items.

Explanation of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 95-08-08.
    Paragraph (a) of the proposal would continue to require 
installation of eight fail-safe straps onto the attach ring, P/N 65ND-
54301-1, of the nose cowl in accordance with Nordam Service Bulletin SB 
71-03. This is the same requirement that was contained in AD 95-08-08. 
Revision 1 of the service bulletin is included as an additional source 
of appropriate service information.
    Paragraph (b) of the proposal would require operators to perform a 
detailed visual inspection to detect cracking of the attach ring of the 
nose cowl, prior to further flight after each incident of turbine blade 
failure. If any cracked attached ring is detected, it would be required 
to be replaced with an attach ring having either P/N 65ND-54301-1 or 
65ND-54301-5. Should an operator elect to replace a cracked attached 
ring with an attach ring having P/N 65ND-54301-1, that replacment would 
be required to be accomplished in accordance with Supplemental Type 
Certification (STC) SA5730NM. Should an operator elect to replace the 
cracked attached ring with an attach ring having P/N 65ND-54301-5, that 
replacement would be required to be accomplished in accrodance with 
Nordam Service Bulletin SB 71-03.
    Paragraph (c) of the proposal provides operators the opportunity to 
terminate the repetitive inspections by installing an attach ring 
having P/N 65ND-54301-5. For the reason discussed previously, the FAA 
is not proposing to mandate this installation, but provides it an an 
optional terminating action for the proposed inspection requirements of 
the AD.

Economic Impact

    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 would be affected by this proposed 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 proposed in this AD action would take 
approximately 10 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the proposed requirements of this AD on the sole U.S. 
operator is estimated to be $600 per airplane per inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no affected 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 39-9197 (60 FR 
19157, April 17, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: 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 
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 use the authority 
provided in paragraph (e) 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 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 

[[Page 57842]]
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 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 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.

    Issued in Renton, Washington, on November 16, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-28546 Filed 11-21-95; 8:45 am]
BILLING CODE 4910-13-U