
[Federal Register: October 1, 2010 (Volume 75, Number 190)]
[Proposed Rules]               
[Page 60665-60667]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr01oc10-22]                         

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0953; Directorate Identifier 2010-NM-010-AD]
RIN 2120-AA64

 
Airworthiness Directives; McDonnell Douglas Corporation Model MD-
90-30 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to adopt a new airworthiness directive (AD) for all 
Model MD-90-30 airplanes. This proposed AD would require repetitive 
high frequency eddy current inspections for cracking on the hinge 
bearing lugs of the left and right sides of the center section ribs of 
the horizontal stabilizer, and related investigative and corrective 
actions if necessary. This proposed AD results from reports of cracks 
found on either the left or right (or in one case, both) sides of the 
center section ribs of the horizontal stabilizer. We are proposing this 
AD to detect and correct cracking in the hinge bearing lugs of the 
center section of the left and right ribs, which could result in 
failure of the hinge bearing lugs and consequent inability of the 
horizontal stabilizer to sustain the required loads.

DATES: We must receive comments on this proposed AD by November 15, 
2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
3855 Lakewood Boulevard, MC D800-0019, Long Beach, California 90846-
0001; telephone 206-544-5000, extension 2; fax 206-766-5683; e-mail 
dse.boecom@boeing.com; Internet https://www.myboeingfleet.com. You may 
review copies of the referenced service information at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington. For information on the availability of this material at the 
FAA, call 425-227-1221.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Roger Durbin, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification 
Office (ACO), 3960 Paramount Boulevard, Lakewood, California 90712-
4137; telephone (562) 627-5233; fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-0953; 
Directorate Identifier 2010-NM-010-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

[[Page 60666]]

Discussion

    We have received seven reports of cracks found on either the left 
or right (or in one case, both) sides of the center section ribs of the 
horizontal stabilizer. These cracks were located on the aft face of the 
hinge bearing lugs on the horizontal stabilizer. Cracks were reported 
on MD-90 airplanes that had accumulated 9,051 to 21,183 total flight 
hours, and 8,939 to 20,893 total flight cycles. The cause of the 
cracking has not been determined. Undetected cracking in the hinge 
bearing lugs of the center section of the left and right ribs, if not 
corrected, could result in failure of the hinge bearing lugs and 
consequent inability of the horizontal stabilizer to sustain the 
required loads.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin MD90-55A016, 
Revision 1, dated February 17, 2010. Boeing Alert Service Bulletin 
MD90-55A016, Revision 1, dated February 17, 2010, describes procedures 
for doing repetitive high frequency eddy current (HFEC) inspections for 
cracking on the hinge bearing lugs on the aft face of the horizontal 
stabilizer center section on the left and right ribs, and doing 
applicable related investigative and corrective actions. The related 
investigative action is measuring the crack length. The corrective 
actions include blending out cracks and replacing the rib of the center 
section of the horizontal stabilizer. For airplanes on which a blend 
out is done, Boeing Alert Service Bulletin MD90-55A016, Revision 1, 
dated February 17, 2010, describes procedures for doing repetitive HFEC 
inspections for cracking of the blend out. For airplanes on which the 
replacement is done, Boeing Alert Service Bulletin MD90-55A016, 
Revision 1, dated February 17, 2010, describes procedures for doing 
repetitive HFEC inspections for cracking of the replaced horizontal 
stabilizer rib.
    For the initial HFEC inspection, Boeing Alert Service Bulletin 
MD90-55A016, Revision 1, dated February 17, 2010, specifies a 
compliance time of before the accumulation of 7,200 total flight cycles 
or within 1,505 flight cycles after the original issue date of Boeing 
Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 
2010, whichever occurs later.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously, except as discussed under 
``Differences Between the Proposed AD and Service Bulletin.''

Differences Between the Proposed AD and Service Bulletin

    For Condition 2A specified in Boeing Alert Service Bulletin MD90-
55A016, Revision 1, dated February 17, 2010, the service bulletin 
specifies doing repetitive inspections of the blend out but did not 
identify corrective actions when cracks are found during those 
inspections. This proposed AD would require replacing the horizontal 
stabilizer center section rib when cracks are found during inspections 
of the blend out. We have coordinated this difference with Boeing.
    For Condition 2B specified in Boeing Alert Service Bulletin MD90-
55A016, Revision 1, dated February 17, 2010, the service bulletin 
specifies doing repetitive inspections of the replaced horizontal 
stabilizer center section rib at intervals not to exceed 1,680 flight 
cycles. This proposed AD would require doing an inspection of the 
replaced horizontal stabilizer center section rib and all applicable 
corrective actions and repetitive inspections (for Condition 1, the 
repetitive interval is 1,680 flight cycles; for Condition 2A, the 
repetitive interval is 400 flight cycles).

Interim Action

    We consider this proposed AD interim action. The manufacturer is 
currently developing a modification that will address the unsafe 
condition identified in this AD. Once this modification is developed, 
approved, and available, we might consider additional rulemaking.

Costs of Compliance

    We estimate that this proposed AD would affect 16 airplanes of U.S. 
registry. We also estimate that it would take about 2 work-hours per 
product to comply with this proposed AD. The average labor rate is $85 
per work-hour. Based on these figures, we estimate the cost of this 
proposed AD to the U.S. operators to be $2,720, or $170 per product.

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 determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 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. 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

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

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new AD:

McDonnell Douglas Corporation: Docket No. FAA-2010-0953; Directorate 
Identifier 2010-NM-010-AD.

[[Page 60667]]

Comments Due Date

    (a) We must receive comments by November 15, 2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all McDonnell Douglas Corporation Model 
MD-90-30 airplanes, certificated in any category.

Subject

    (d) Air Transport Association (ATA) of America Code 55: 
Stabilizers.

Unsafe Condition

    (e) This AD results from reports of cracks found on either the 
left or right (or in one case, both) sides of the center section 
ribs of the horizontal stabilizer. The Federal Aviation 
Administration is issuing this AD to detect and correct cracking in 
the hinge bearing lugs of the center section of the left and right 
ribs, which could result in failure of the hinge bearing lugs and 
consequent inability of the horizontal stabilizer to sustain the 
required loads.

Compliance

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

Repetitive Inspections and Corrective Actions for Cracking

    (g) At the applicable time in paragraph 1.E., ``Compliance,'' of 
Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated 
February 17, 2010, except as required by paragraph (n) of this AD, 
do a high frequency eddy current (HFEC) inspection for cracking on 
the hinge bearing lugs of the left and right sides of the center 
section ribs of the horizontal stabilizer, and do all applicable 
related investigative actions, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin MD90-55A016, Revision 
1, dated February 17, 2010. Do all applicable related investigative 
actions before further flight.
    (h) If during any inspection required by paragraph (g) of this 
AD, no cracking is found, repeat the inspection required by 
paragraph (g) of this AD thereafter at intervals not to exceed 1,680 
flight cycles.
    (i) If during any inspection required by paragraph (g) or (h) of 
this AD, any crack is found having a length between Points `A' and 
`B' less than or equal to 0.15 inch and crack length between Points 
`C' and `D' less than or equal to 0.05 inch, as identified in Boeing 
Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 
2010: Before further flight, blend out the crack; and within 1,000 
flight cycles after doing the blend out, do an HFEC inspection of 
the blend out on the center section rib hinge bearing lug; in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010. 
Repeat the HFEC inspection of the blend out thereafter at intervals 
not to exceed 400 flight cycles until the replacement specified by 
paragraph (j) is done.
    (j) If any cracking is detected during any inspection required 
by paragraph (i) of this AD, before further flight, replace the 
horizontal stabilizer center section rib with a new horizontal 
stabilizer center section rib, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin MD90-55A016, Revision 
1, dated February 17, 2010.
    (k) If during any inspection required by paragraph (g) or (h) of 
this AD, any crack is found having a length between Points `A' and 
`B' greater than 0.15 inch or crack length between Points `C' and 
`D' greater than 0.05 inch, as identified in Boeing Alert Service 
Bulletin MD90-55A016, Revision 1, dated February 17, 2010: Before 
further flight, replace the horizontal stabilizer center section rib 
with a new horizontal stabilizer center section rib, in accordance 
with the Accomplishment Instructions of Boeing Alert Service 
Bulletin MD90-55A016, Revision 1, dated February 17, 2010.
    (l) For any airplane having a horizontal stabilizer center 
section rib replaced during the actions required by paragraph (j) or 
(k) of this AD: Before the accumulation of 7,200 total flight cycles 
on the new horizontal stabilizer center section rib, do the actions 
required by paragraph (g) of this AD, and do all applicable actions 
specified in paragraphs (h), (i), (j), and (k) of this AD.

Credit for Actions Accomplished According to Previous Issue of Service 
Bulletin

    (m) Actions accomplished before the effective date of this AD 
according to Boeing Alert Service Bulletin MD90-55A016, dated 
December 16, 2009, are considered acceptable for compliance with the 
corresponding actions required by paragraphs (g), (h), (i), (j), and 
(k) of this AD.

Exceptions to the Service Bulletin

    (n) Where Boeing Alert Service Bulletin MD90-55A016, Revision 1, 
dated February 17, 2010, specifies a compliance time ``after the 
original issue date on the service bulletin,'' this AD requires 
compliance within the specified compliance time after the effective 
date of this AD.

Alternative Methods of Compliance (AMOCs)

    (o)(1) The Manager, Los Angeles ACO, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. Send information to ATTN: Roger Durbin, Aerospace 
Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft 
Certification Office (ACO), 3960 Paramount Boulevard, Lakewood, 
California 90712-4137; telephone (562) 627-5233; fax (562) 627-5210.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD if it is approved by the 
Boeing Commercial Airplanes Organization Designation Authorization 
(ODA) that has been authorized by the Manager, Los Angeles ACO to 
make those findings. For a repair method to be approved, the repair 
must meet the certification basis of the airplane, and the approval 
must specifically refer to this AD.

    Issued in Renton, Washington, on September 23, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-24715 Filed 9-30-10; 8:45 am]
BILLING CODE 4910-13-P

