AD 2006-07-21

[Federal Register Volume 71, Number 69 (Tuesday, April 11, 2006)]
[Rules and Regulations]
[Pages 18207-18210]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 06-3381]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19140; Directorate Identifier 2004-NM-84-AD; 
Amendment 39-14548; AD 2006-07-21]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 Airplanes Powered by 
Pratt & Whitney Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 757 airplanes. This AD requires repetitive 
inspections for corrosion and cracking of the midspar fittings in the 
nacelle struts, and corrective actions if necessary. This AD also 
provides an optional terminating action for the repetitive inspections. 
This AD results from reports of corrosion and cracking on midspar 
fittings on the nacelle struts of several Boeing Model 757 airplanes. 
We are issuing this AD to detect and correct cracking in the midspar 
fittings of the nacelle struts, consequent reduced structural integrity 
of the struts, and possible separation of an engine and strut from the 
airplane.

DATES: This AD becomes effective May 16, 2006.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of May 16, 2006.

ADDRESSES: You may examine the AD docket on the Internet at <a href="http://dms.dot.gov">http://dms.dot.gov</a> or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street SW., Nassif Building, 
room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Dennis Stremick, Aerospace Engineer, 
Airframe Branch, ANM-120S, Seattle Aircraft Certification Office, FAA, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6450; fax (425) 914-6590.

SUPPLEMENTARY INFORMATION:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at <a href="http://dms.dot.gov">http://dms.dot.gov</a> or in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that would apply to certain Boeing Model 
757 series airplanes. That NPRM was published in the Federal Register 
on September 21, 2004 (69 FR 56375). That NPRM proposed to require 
repetitive inspections for corrosion and cracking of the midspar 
fittings in the nacelle struts, and corrective actions if necessary. 
That NPRM also proposed to provide an optional terminating action for 
the repetitive inspections.

Explanation of Revised Service Information

    Since we issued the NPRM, Boeing revised Special Attention Service 
Bulletin 757-54-0042, dated May 13, 1999, which was specified in the 
NPRM as the appropriate source of service information for accomplishing 
the proposed requirements of this AD. We have reviewed Boeing Service 
Bulletin 757-54-0042, Revision 1, dated July 7, 2005, which, among 
other changes, incorporates the information specified in Boeing 
Information Notices 757-54-0042 IN 01, dated July 22, 1999; 757-54-0042 
IN 02, dated January 6, 2000; and 757-54-0042 IN 03, dated November 21, 
2000; revises incorrect part number references; and contains a revised 
Figure 6.
    Figure 6 of Service Bulletin 757-54-0042, Revision 1, specifies an 
optional action to replacing any cracked or corroded midspar fitting. 
That option involves one-time high-frequency eddy current (HFEC) and 
borescope inspections to detect corrosion or cracking within the 
fitting bolt holes. Revision 1 also describes the related repair of any 
cracked or corroded bolt hole; and repetitive detailed inspections and 
general visual inspections for recurrent corrosion or cracking of the 
repaired fitting until the fitting is replaced. We have determined that 
these new inspections and corrective actions are adequate to maintain 
airplane operational safety, and we have revised the AD to refer to 
Service Bulletin 757-54-0042, Revision 1, as the appropriate source of 
service information for accomplishing the requirements of the AD, 
except as discussed under ``Difference Between Service Information and 
This AD.''

Difference Between Service Information and This AD

    Service Bulletin 757-54-0042, Revision 1, specifies to contact the 
manufacturer for instructions on how to repair certain conditions, but 
this AD requires repairing those conditions in one of the following 
ways:
    <bullet> Using a method that we approve; or
    <bullet> Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

AD Not Applicable

    One commenter, American Airlines, states that none of its airplanes 
are affected by this AD.

Request To Correct Errors in Service Information

    Two commenters, ATA and UPS, request that we revise the service 
information. The commenters state that Boeing has released 3 INs that 
correct errors in the service bulletins, but that the INs are not FAA-
approved. Therefore, the commenters assert that

[[Page 18208]]

the INs should be incorporated in the service bulletin before the AD is 
released.
    We agree with this request, as Boeing has revised the service 
bulletin to incorporate the INs as previously discussed. The AD has 
been changed to specify the revised service bulletin as the appropriate 
source of service information.

Request for Delayed Replacement of Fittings

    One commenter, Boeing, requests that we allow up to 18 months to 
replace any midspar fitting following the detection of corrosion of 
that fitting. The commenter states that the additional inspections and 
actions specified in Service Bulletin 757-54-0042, Revision 1, will 
allow the airplane to operate safely for up to 18 months without 
replacing the corroded midspar fitting.
    We agree with this request, as we have agreed to update the service 
information reference as previously discussed. We have revised 
paragraphs (h) and (i) of the NPRM and added new paragraph (j) to 
describe the corrective actions. We have added new paragraph (k) to 
describe optional investigative actions which would allow up to 18 
months to replace any midspar fitting discovered with signs of 
corrosion or cracking; and to clarify the fitting repair, repetitive 
inspection, and replacement instructions of Service Bulletin 757-54-
0042, Revision 1. We added new paragraph (m) to give credit for actions 
accomplished prior to the effective date of this AD in accordance with 
Boeing Special Attention Service Bulletin 757-54-0042, dated May 13, 
1999. Consequently, we have re-identified existing paragraphs (j), (k), 
and (l) of the NPRM as paragraphs (l), (n), and (o) in this AD.

Request To Develop Non-Destructive Test for Cracking

    One commenter, ATA, requests that a non-destructive testing (NDT) 
procedure for cracking be developed prior to the release of the final 
rule. This NDT procedure would apply to holes that display evidence of 
corrosion. The commenter states that, though such a procedure does not 
exist for Model 757 airplanes, such procedures do exist and are 
required for Model 767 airplanes.
    We agree with this request. As discussed previously, Service 
Bulletin 757-54-0042, Revision 1, specifies new NDT procedures for HFEC 
and borescope inspections of the midspar fitting bolt holes, and we 
have revised the AD to require these inspections, if corrosion or 
cracking is found and the fitting is not immediately replaced with a 
new, improved fitting.

Request To Permit Continued Operation After Staining Discovered

    One commenter, UPS, requests that continued operation be permitted 
after the discovery of staining on the fittings. The commenter states 
that fittings discovered to have corrosion stains after multiple 
repetitions of the 300-flight-cycle inspection should be inspected in 
greater detail to determine the extent of the corrosion. The commenter 
gives no technical justification for this request.
    We do not agree with this request. The commenter asserts the 
service bulletin states that, after the discovery of staining, no 
corrective actions need be taken until several repetitions of the 300 
flight cycle inspection have been accomplished, at which time further 
investigative actions would be appropriate. However, staining is 
evidence of active corrosion and stress corrosion cracking (SCC) is 
time dependent; the longer a corroded fitting remains in service with 
no corrective action, the more likely it becomes that a crack will 
start and propagate, with possible consequent failure of the fitting. 
We have not changed this AD in this regard.

Request To Reinstate 300-Flight-Cycle Inspection and Lubrication 
Interval

    Two commenters, ATA and United Airlines, request that the 300-
flight-cycle interval for inspection and lubrication originally 
specified by Special Attention Service Bulletin 757-54-0042 be 
reinstated. One commenter states that a general visual inspection of 
the midspar fittings revealed no corrosion or cracking. The commenters 
feel that inspection and lubrication performed every 300 flight cycles 
should permit airplane operation with adequate safety.
    We do not agree with this request. We examined a midspar fitting, 
which showed major corrosion at the faying surface around one bolt hole 
with a crack emanating from that bolt hole. Further, another crack 
emanated from a second bolt hole. Therefore, we do not agree that 
inspection and lubrication as suggested by the commenters would provide 
adequate airplane safety. However, as previously discussed, Service 
Bulletin 757-54-0042, Revision 1, specifies HFEC and borescope 
inspections of the bolt holes of any cracked or corroded midspar 
fitting and, provided necessary corrective action is taken after those 
inspections, permits continued operation of the airplane as long as 
repetitive detailed inspections of any repaired fitting are performed 
until the fitting is replaced, and we have revised the AD to reflect 
this.

Request To Withdraw Proposed AD

    One commenter, ATA, requests that we withdraw the proposed AD. The 
commenter states that the AD is not necessary, since only one midspar 
fitting has been found with cracking, and asserts operators should be 
able to wait to inspect, repair, and replace any subject midspar 
fittings until the Model 757 Strut Improvement Program (SIP) can be 
accomplished.
    We do not agree. While the threshold for the SIP program is at 
twenty years (240 months) or 37,500 flight cycles, whichever occurs 
first, the cracked midspar fitting was discovered on an airplane that 
was about 17 years old and had accumulated less than 30,000 total 
flight cycles. Further, the damaged fitting showed two cracks that had 
propagated from SCC, and, as the suspect fittings are made of heat-
treated 4330M stock, all mounting holes of such fittings are 
susceptible to SCC. The actions specified in this AD are necessary to 
ensure adequate airplane safety prior to accomplishing the SIP; 
therefore, the AD will not be withdrawn.

Request To Correct Threshold Limits

    Two commenters, United Airlines and UPS, state that the threshold 
limits specified in the ``Other Related Rulemaking'' paragraph of the 
NPRM are incorrect. Though the commenters do not make a request or 
provide data to support this position, it appears the commenters wish 
us to revise those limits.
    We do not agree. Although paragraph (d) of AD 2003-18-05, amendment 
39-13296 (68 FR 53496, September 11, 2003), requires replacing the 
upper link of the strut in accordance with Boeing Service Bulletin 757-
54-0036, dated May 14, 1998, prior to the accumulation of 27,000 total 
flight cycles for Model 757-200 airplanes or 29,000 total flight cycles 
for Model 757-200PF airplanes, the threshold for the entire SIP remains 
at 20 years or 37,000 flight cycles, whichever occurs first. Our intent 
was to give credit to operators who have already accomplished the SIP, 
but we acknowledge that discussing these threshold limits could have 
caused confusion. However, as the ``Other Related Rulemaking'' 
paragraph of the NPRM is not repeated in the final rule, no change is 
needed to this AD in this regard.

Explanation of Change to Applicability

    We have revised the applicability of the existing AD to identify 
model

[[Page 18209]]

designations as published in the most recent type certificate data 
sheet for the affected models.

Clarification of AMOC Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously, 
as well as certain minor editorial changes. We have determined that 
these changes will neither increase the economic burden on any operator 
nor increase the scope of the AD.

Costs of Compliance

    This AD will affect about 410 airplanes worldwide. The following 
table provides the estimated costs for U.S. operators to comply with 
this AD.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                         Average                                    Number of
                                 Work     labor                     Cost per          U.S.-
            Action              hours    rate per     Parts         airplane       registerred     Fleet cost
                                           hour                                     airplanes
----------------------------------------------------------------------------------------------------------------
Inspection, per inspection          3        $65   None.......  $195, per                 338   $65,910, per
 cycle.                                                          inspection                      inspection
                                                                 cycle                           cycle
----------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD and placed it in the AD docket. See the ADDRESSES 
section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

2006-07-21 Boeing: Amendment 39-14548. Docket No. FAA-2004-19140; 
Directorate Identifier 2004-NM-84-AD.

Effective Date

    (a) This AD becomes effective May 16, 2006.

Affected ADs

    (b) This AD is related to AD 2003-18-05.

Applicability

    (c) This AD applies to Boeing Model 757-200, and -200PF 
airplanes, certificated in any category; having line numbers 1 
through 639 inclusive; powered by Pratt & Whitney engines.

Unsafe Condition

    (d) This AD results from reports of corrosion and cracking on 
midspar fittings on the nacelle struts of several Boeing Model 757 
airplanes. We are issuing this AD to detect and correct cracking in 
the midspar fittings of the nacelle struts, consequent reduced 
structural integrity of the struts, and possible separation of an 
engine and strut from the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Inspections for Group 1 Airplanes

    (f) For airplanes identified as Group 1 in Boeing Service 
Bulletin 757-54-0042, Revision 1, dated July 7, 2005--which is 
referred to after this paragraph as ``the service bulletin'': Within 
18 months after the effective date of this AD, do general visual and 
detailed inspections for evidence of corrosion and/or cracking of 
the midspar fittings located in the nacelle struts, in accordance 
with the Accomplishment Instructions of the service bulletin. Repeat 
the inspections thereafter at intervals not to exceed 18 months 
until the requirements of paragraph (l) of this AD are accomplished.

    Note 1: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made from within 
touching distance unless otherwise specified. A mirror may be 
necessary to ensure visual access to all exposed surfaces in the 
inspection area. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or droplight and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''


    Note 2: For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation,

[[Page 18210]]

or assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Inspections for Group 2 Airplanes

    (g) For airplanes identified as Group 2 in the service bulletin: 
Within 18 months after the effective date of this AD, identify the 
type of material used to make the midspar fittings, in accordance 
with Figure 4 of the Accomplishment Instructions of the service 
bulletin.
    (1) If all four midspar fittings are made of 15-5PH CRES 
material, no further action is required by this AD.
    (2) If any midspar fitting is made of 4330M material, do the 
inspections required by paragraph (h) of this AD.
    (h) For Group 2 airplanes with any fittings made of 4330M 
material: After identifying the fitting material as required by 
paragraph (g) of this AD, but before further flight: Do a general 
visual inspection and a detailed inspection of the 4330M midspar 
fittings for evidence of corrosion and/or cracking, in accordance 
with the Accomplishment Instructions of the service bulletin. Repeat 
the inspections for corrosion and/or cracking thereafter at 
intervals not to exceed 18 months until the requirements of 
paragraph (l) of this AD are accomplished.

Cracking or Corrosion

    (i) For Group 1 and Group 2 airplanes: If any evidence of 
corrosion or cracking is found during any action required by 
paragraph (f) or (h) of this AD, before further flight, perform the 
corrective actions of paragraph (j) of this AD or the optional 
investigative actions of paragraph (k) of this AD.

Corrective Actions

    (j) Replace the affected midspar fitting with a new midspar 
fitting by accomplishing all of the applicable actions in accordance 
with the Accomplishment Instructions of the service bulletin. 
Replacement of an affected midspar fitting terminates the repetitive 
inspections required by paragraphs (f) and (h) of this AD for that 
fitting only.

Optional Investigative Actions

    (k) Perform one-time high-frequency eddy current (HFEC) and 
borescope inspections of any cracked or corroded bolt hole; and, 
before further flight, perform the applicable actions of paragraph 
(k)(1) or (k)(2) of this AD; in accordance with the Accomplishment 
Instructions of the service bulletin.
    (1) Repair corrosion damage or cracking of any bolt hole as 
specified in Figure 6 of the Accomplishment Instructions of the 
service bulletin; then accomplish paragraph (k)(1)(i) or (k)(1)(ii) 
of this AD as applicable.
    (i) Perform repetitive detailed inspections of any repaired bolt 
hole in accordance with Figure 7 of the service bulletin, at 
intervals not to exceed 300 flight cycles or 75 days, whichever 
occurs first, until the fitting is replaced as specified in 
paragraph (l) of this AD. Replace the repaired fitting with a new, 
improved fitting no later than 18 months after the repair of the 
bolt hole, or prior to further flight if any further evidence of 
corrosion or cracking is found in that fitting during any inspection 
required by this paragraph. Replacement of any fitting terminates 
the inspections required by paragraphs (f), (h), and (k)(1)(i) of 
this AD for that fitting only.
    (ii) Replace the midspar fitting with a new, improved fitting, 
in accordance with paragraph (j) of this AD. Replacement of any 
fitting terminates the inspections required by paragraph (f), (h), 
and (k)(1)(i) of this AD for that fitting only.
    (2) If any corrosion damage or cracking found during any 
inspection required by this AD cannot be repaired in accordance with 
paragraph (k)(1) of this AD, and the service bulletin specifies to 
contact Boeing for appropriate action, before further flight, 
perform the actions in paragraph (k)(2)(i) or (k)(2)(ii) of this AD, 
as applicable.
    (i) Repair the corrosion damage or cracking using a method 
approved in accordance with the procedures specified in paragraph 
(o) of this AD.
    (ii) Replace the midspar fitting with a new, improved fitting, 
in accordance with paragraph (l) of this AD.

Optional Terminating Action

    (l) Replacement of all of the midspar fittings with new, 
improved midspar fittings in accordance with the Accomplishment 
Instructions of the service bulletin terminates the repetitive 
inspections required by paragraphs (f), (h), and (k)(1)(i) of this 
AD.

Actions Accomplished Using Prior Version of Service Information

    (m) Replacement of the midspar fitting(s) with new, improved 
fittings before the effective date of this AD in accordance with 
Boeing Special Attention Service Bulletin 757-54-0042, dated May 13, 
1999, is considered acceptable for compliance with the applicable 
action specified in this AD. Inspection of any fitting accomplished 
in accordance with Boeing Special Attention Service Bulletin 757-54-
0042, dated May 13, 1999, before the effective date of this AD, with 
no findings of cracking or corrosion, are considered acceptable for 
compliance with the inspection required by paragraph (f) or (h) of 
this AD, as applicable, for that fitting only.

Previous Nacelle Strut and Wing Modification

    (n) Accomplishment of the nacelle strut and wing modification 
required by AD 2003-18-05 is considered acceptable for compliance 
with the requirements of this AD.

Alternative Methods of Compliance (AMOCs)

    (o)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with 14 CFR 
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any replacement required by this AD, if it is approved by a 
Boeing Company Designated Engineering Representative who has been 
authorized by the Manager, Seattle ACO, to make those findings.

Material Incorporated by Reference

    (p) You must use Boeing Service Bulletin 757-54-0042, Revision 
1, dated July 7, 2005, to perform the actions that are required by 
this AD, unless the AD specifies otherwise. The Director of the 
Federal Register approved the incorporation by reference of this 
document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for a copy of this service information. You 
may review copies at the Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street SW., room PL-401, Nassif 
Building, Washington, DC; on the Internet at <a href="http://dms.dot.gov">http://dms.dot.gov</a>; or 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at the NARA, call 
(202) 741-6030, or go to <a href="http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html">http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html</a> html.

    Issued in Renton, Washington, on March 30, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3381 Filed 4-10-06; 8:45 am]
BILLING CODE 4910-13-P