[Federal Register Volume 70, Number 14 (Monday, January 24, 2005)]
[Proposed Rules]
[Pages 3320-3322]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-1220]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20110; Directorate Identifier 2004-NM-114-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 Series Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-600, -700, -700C, -800, and -900 series 
airplanes. This proposed AD would require repetitive general visual 
inspections for dirt, debris, and drain blockage and cleaning of the 
aft fairing cavities of the engine struts; and modification of the aft 
fairings, which would terminate the repetitive general visual 
inspections. This proposed AD is prompted by a report indicating that 
water had accumulated in the cavities of the engine strut aft fairings. 
We are proposing this AD to prevent drain blockage by debris that, when 
combined with leaking, flammable fluid lines passing through the engine 
strut aft fairing, could allow flammable fluids to build up in the 
cavity of the aft fairing, and consequently could be ignited by the 
engine exhaust nozzle located below the engine strut, resulting in an 
explosion or uncontrolled fire.

DATES: We must receive comments on this proposed AD by March 10, 2005.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide Rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     By Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street SW., Washington, DC, 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, P.O. Box 3707, Seattle, Washington 98124-
2207.
    You can examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street SW., room PL-401, on 
the plaza level of the Nassif Building, Washington, DC. This docket 
number is FAA-2005-20110; the directorate identifier for this docket is 
2004-NM-114-AD.

FOR FURTHER INFORMATION CONTACT: Doug Pegors, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6504; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2005-20110; 
Directorate Identifier 2004-NM-114-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments submitted by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You can review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
can visit http://dms.dot.gov.

Examining the Docket

    You can examine the AD docket on the Internet at http://dms.dot.gov, 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 DOT 
street address stated in the ADDRESSES

[[Page 3321]]

section. Comments will be available in the AD docket shortly after the 
DMS receives them.

Discussion

    We have received a report indicating that water had accumulated in 
the cavities of the engine strut aft fairings on several Boeing Model 
737-700 series airplanes. Build up of debris in the sump area of the 
cavity of the aft fairing had blocked the drain, which caused 
approximately 12 inches of water to accumulate. Debris and water had 
entered through gaps between the engine strut fairing and the thrust 
reverser skirt fairing at the wing interface blade seal. A drain 
blocked by debris in combination with flammable fluid lines, which pass 
through the engine strut aft fairing and occasionally leak, could cause 
a hazardous amount of flammable fluid to build up in the cavity of the 
aft fairing. This condition, if not corrected, could result in the 
ignition of the flammable fluid by the exhaust nozzle located below the 
engine strut and consequent explosion or uncontrolled fire.
    The aft fairing of the engine strut on certain Boeing Model 737-
600, -700C, -800, and -900 series airplanes are identical to those on 
the affected Model 737-700 series airplanes. Therefore, all of these 
models may be subject to the same unsafe condition.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-54-
1041, dated January 22, 2004. The service bulletin describes procedures 
for repetitive general visual inspections for dirt, debris, and drain 
blockage and cleaning of the aft fairing cavities of the left and right 
engine struts; and modification of the aft fairings of the left and 
right engine struts, which eliminates the need for repetitive general 
visual inspections. Modification involves installing new, improved 
seals on the inboard and outboard sides of the aft fairings of the left 
and right engine struts. Accomplishing the actions specified in the 
service information is intended to adequately address the unsafe 
condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. Therefore, we are proposing this AD, which 
would require repetitive general visual inspections for dirt, debris, 
and drain blockage and cleaning of the aft fairing cavities of the left 
and right engine struts; and modification of the aft fairings of the 
left and right engine struts, which would terminate the repetitive 
general visual inspections. Modification involves installing new, 
improved seals on the inboard and outboard sides of the aft fairings of 
the left and right engine struts. The proposed AD would require you to 
use the service information described previously to perform these 
actions, except as discussed under ``Differences Between the Proposed 
AD and Service Bulletin.''

Differences Between Proposed AD and Service Bulletin

    Boeing Special Attention Service Bulletin 737-54-1041, dated 
January 22, 2004, specifies that operators may accomplish the general 
visual inspection and cleaning of the aft fairing cavities in 
accordance with either the Boeing 737-600/700/800/900 Airplane 
Maintenance Manual (AMM) or an ``approved equivalent procedure.'' 
However, this proposed AD would require operators to accomplish the 
actions in accordance with the procedures specified in Chapter 54-55-02 
of the Boeing 737-600/700/800/900 AMM. An ``approved equivalent 
procedure'' may be used only if approved as an alternative method of 
compliance in accordance with paragraph (j) of this AD.
    The proposed AD would require inspecting and cleaning the drain 
system of an aft fairing after the modifications required by paragraph 
(i) of this AD. We have determined that modification alone would not 
eliminate the build up of debris and flammable fluids in the cavity of 
the aft fairing since the most previous inspection. Therefore, 
operators must inspect and clean the aft fairings when the modification 
is done.

Costs of Compliance

    This proposed AD would affect about 1,406 airplanes worldwide. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                        Average                                      Number of
                                Work     labor                         Cost per        U.S.-
           Action              hours    rate per       Parts           airplane      registered     Fleet cost
                                          hour                                       airplanes
----------------------------------------------------------------------------------------------------------------
Inspection, per inspection          2        $65  None...........  $130, per                549  $71,370, per
 cycle.                                                             inspection                    inspection
                                                                    cycle.                        cycle.
Modification................        5         65  $294...........  619............          549  339,831.
----------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. 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.
    This rulemaking is promulgated 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 AD.

Regulatory Findings

    We have 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 that the 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,

[[Page 3322]]

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 proposed AD. 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, 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 
airworthiness directive (AD):

Boeing: Docket No. FAA-2005-20110; Directorate Identifier 2004-NM-
114-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by March 10, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, -800, 
and -900 series airplanes, certificated in any category; as listed 
in Boeing Special Attention Service Bulletin 737-54-1041, dated 
January 22, 2004.

Unsafe Condition

    (d) This AD was prompted by a report indicating that water had 
accumulated in the cavities of the engine strut aft fairings. We are 
issuing this AD to prevent drain blockage by debris that, when 
combined with leaking, flammable fluid lines passing through the 
engine strut aft fairing, could allow flammable fluids to build up 
in the cavity of the aft fairing, and consequently could be ignited 
by the engine exhaust nozzle located below the engine strut, 
resulting in an explosion or uncontrolled fire.

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.

Service Bulletin Reference

    (f) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-54-1041, dated January 22, 2004.

Repetitive Inspections of the Engine Strut Aft Fairings

    (g) Within 4,000 flight cycles or within 30 months after the 
effective date of this AD, whichever occurs first: Do the actions 
specified in paragraphs (g)(1) and (g)(2) of this AD.
    (1) Do a general visual inspection for dirt, debris, and drain 
blockage and clean the aft fairing cavity of the left engine strut, 
in accordance with Part I of the service bulletin, except as 
provided by paragraph (h) of this AD. Thereafter at intervals not to 
exceed 4,000 flight cycles or 30 months, whichever occurs first: 
Repeat the inspection until the aft fairing of the left engine strut 
has been modified in accordance with paragraph (i)(1) of this AD.
    (2) Do a general visual inspection for dirt, debris, and drain 
blockage and clean the aft fairing cavity of the right engine strut, 
in accordance with Part II of the service bulletin, except as 
provided by paragraph (h) of this AD. Thereafter at intervals not to 
exceed 4,000 flight cycles or 30 months, whichever occurs first: 
Repeat the inspection until the aft fairing of the right engine 
strut has been modified in accordance with paragraph (i)(2) of this 
AD.

    Note 1: For the purposes of this AD, a general visual inspection 
is: ``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 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.''

Approved Equivalent Procedure

    (h) If the service bulletin specifies that the general visual 
inspection and cleaning of the aft fairing cavity of the left or 
right engine strut may be accomplished per an ``approved equivalent 
procedure'': The general visual inspection or cleaning must be 
accomplished in accordance with the chapter of the Boeing 737-600/
700/800/900 Airplane Maintenance Manual specified in the service 
bulletin.

Modification of the Engine Strut Aft Fairings

    (i) Within 9,000 flight cycles after the effective date of this 
AD, do the actions specified in paragraphs (i)(1) and (i)(2) of this 
AD.
    (1) Modify the aft fairing of the left engine strut, in 
accordance with Part III of the service bulletin; and after 
accomplishing the modification but before further flight, inspect 
and clean the drain system of the aft fairing in accordance with 
Part I of the service bulletin. This modification terminates the 
repetitive inspections required by paragraph (g)(1) of this AD.
    (2) Modify the aft fairing of the right engine strut, in 
accordance with Part IV of the service bulletin; and after 
accomplishing the modification but before further flight, inspect 
and clean the drain system of the aft fairing in accordance with 
Part II of the service bulletin. This modification terminates the 
repetitive inspections required by paragraph (g)(2) of this AD.

Alternative Methods of Compliance (AMOCs)

    (j) The Manager, Seattle Aircraft Certification Office, FAA, has 
the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.

    Issued in Renton, Washington, on January 12, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-1220 Filed 1-21-05; 8:45 am]
BILLING CODE 4910-13-P