DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
14 CFR Part 39
[Docket No. FAA-2008-0413; Directorate Identifier 2008-NM-003-AD] RIN
2120-AA64
AIRWORTHINESS DIRECTIVES; Boeing Model 737-600, -700, -700C, -800, -900,
and 900ER Series Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Boeing Model 737-600, -700, -700C, -800, -900, and 900ER series
airplanes. This proposed AD would require replacing the pushrods for the
left and right elevator tab control mechanisms with new, improved
pushrods. This proposed AD results from a report of a rod end fracture on
a rudder Power Control Unit (PCU) control rod, which is similar to the
ones used for the elevator tab pushrods. Analysis revealed that the
fractured rod end had an incorrect hardness, which had probably occurred
during the manufacture of the control rod. We are proposing this AD to
prevent fracture of the elevator tab pushrod ends, which could result in
excessive in-flight vibrations of the elevator tab, possible loss of the
elevator tab, and consequent loss of controllability of the airplane.
DATES: We must receive comments on this proposed AD by June 9, 2008.
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 AD, contact Boeing Commercial
Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.
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: Tamara Anderson, Aerospace Engineer, Air-
frame Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601
Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6421;
fax (425) 917-6590.
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-2008-0413; Directorate
Identifier 2008-NM-003-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.
DISCUSSION
We have received a report of a rod end fracture on a rudder Power Control
Unit (PCU) control rod, which is similar to the ones used for the elevator
tab pushrods. An operator found a broken rudder PCU control rod during
heavy maintenance of a Model 737-800 airplane. Analysis revealed that the
fractured rod end had an incorrect hardness, which had probably occurred
during the manufacture of the control rod. During the manufacturing
process, specific areas of the control rods are to be masked off to
prevent the application of the heat treatment/carburization process in
those areas. But at different site locations of the supplier, the heat
treatment/carburization process was done differently, which resulted in
the application of the heat treatment/carburization process of some
control rods in incorrect areas. This caused an incorrect hardness of the
hollow shanks of the rod ends, and resulted in the occurrence of cracks at
the time of manufacture. Further analysis revealed that all control rods
made by the supplier were also affected by the incorrect manufacturing
procedure. Subsequently, an improved design of the control rod was
developed to change from hollow shank rod ends to solid shank rod ends,
which would prevent the problems with the heat treatment/carburization
process during manufacture. Fracture of the elevator tab pushrod ends
could result in excessive in-flight vibrations of the elevator tab,
possible loss of the elevator tab, and consequent loss of controllability
of the airplane.
RELEVANT SERVICE INFORMATION
We have reviewed Boeing Special Attention Service Bulletin 737-27- 1284,
dated November 28, 2007. The service bulletin describes procedures for
replacing the pushrods for the left and right elevator tab control
mechanism with new, improved pushrods. The service bulletin specifies
doing the replacement within 4 years after the date on the service
bulletin.
OTHER RELATED RULEMAKING
On January 29, 2003, the FAA issued AD 2003-03-22, amendment 39- 13047 (68
FR 5819, February 5, 2003), which applies to certain Boeing Model 737-600,
-700, -700C, -800, and -900 series airplanes. AD 2003- 03-22 requires
accomplishing the modification in accordance with Boeing Alert Service
Bulletin 737-55A1080, dated September 19, 2002, and Service Bulletin 737
-27-1284 specifies prior or concurrent accomplishment of Service Bulletin
737-55A1080. AD 2003-03-22 requires installing speedbrake limitation
placards in the flight compartment, and revising the Limitations Section
of the Airplane Flight Manual to ensure the flightcrew is advised not to
extend the speedbrake lever beyond the flight detent. For Model 737-600,
-700, -700C, -800 series airplanes having line numbers 1 through 1174
inclusive, AD 2003-03-22 requires modifying the elevator and elevator tab
assembly before the accumulation of 18,000 total flight cycles, or within
2 years after March 12, 2003, whichever occurs first.
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.
COSTS OF COMPLIANCE
We estimate that this proposed AD would affect 715 airplanes of U.S.
registry. We also estimate that it would take about 4 work-hours per
product to comply with this proposed AD. The average labor rate is $80 per
work-hour. Required parts would cost about $8,036 per product. Based on
these figures, we estimate the cost of this proposed AD to the U.S.
operators to be $5,974,540, or $8,356 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, 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: