[Federal Register Volume 73, Number 82 (Monday, April 28, 2008)]
[Proposed Rules]
[Pages 22840-22845]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-9193]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0415; Directorate Identifier 2007-NM-256-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Boeing Model 737 airplanes. This proposed AD would require 
repetitive inspections, lubrications, and repetitive repairs/overhauls 
of the ball nut and ballscrew and attachment (Gimbal) fittings for the 
trim actuator of the horizontal stabilizer; various installation(s); 
and corrective actions if necessary; as applicable. This proposed AD 
results from a report of extensive corrosion of a ballscrew used in the 
drive mechanism of the horizontal stabilizer trim actuator (HSTA). We 
are proposing this AD to prevent an undetected failure of the primary 
load path for the ballscrew in the drive mechanism of the HSTA and 
subsequent wear and failure of the secondary load path, which could 
lead to loss of control of the horizontal stabilizer and consequent 
loss of control of the airplane.

DATES: We must receive comments on this proposed AD by June 12, 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.,

[[Page 22841]]

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: Kelly McGuckin, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6490; 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-2008-0415; 
Directorate Identifier 2007-NM-256-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

    On January 31, 2000, there was an accident involving a McDonnell 
Douglas Model DC-9-83 (MD-83) airplane. The National Transportation 
Safety Board (NTSB) determined that the probable cause of the accident 
was a loss of airplane pitch control resulting from the in-flight 
failure of the acme nut threads of the jackscrew assembly of the 
horizontal stabilizer trim system. The NTSB concluded that the thread 
failure was caused by excessive wear, resulting from insufficient 
lubrication of the jackscrew assembly. The drive mechanism of the 
horizontal stabilizer on Model MD-83 airplanes has a jackscrew assembly 
with an acme screw. The drive mechanism of the horizontal stabilizer on 
Boeing Model 737 airplanes has a horizontal stabilizer trim actuator 
(HSTA) with a ballscrew. Acme screws and ballscrews have some 
differences in design, but perform similar functions and have the same 
airplane-level effect following failure.
    In response to this accident, Boeing initiated a design review and 
safety analysis of the primary and secondary load paths of the 
ballscrew assembly used on the HSTA of their airplanes. During this 
review, one operator of a Model 757 airplane reported extensive 
corrosion of a ballscrew assembly of the HSTA. Investigation revealed 
extensive corrosion of the primary load path ball bearings in the 
ballscrew assembly. This condition, if not corrected, could result in 
an undetected failure of the primary load path for the ballscrew in the 
drive mechanism of the HSTA and subsequent wear and failure of the 
secondary load path, which could lead to loss of control of the 
horizontal stabilizer and consequent loss of control of the airplane.
    The ballscrew assembly on Model 757 airplanes is similar to those 
on the affected Model 737 airplanes. Therefore, all of these models may 
be subject to the same unsafe condition.

Other Relevant Rulemaking

    We are considering additional rulemaking to address the identified 
unsafe condition on Model 757 airplanes.

Relevant Service Information

    We have reviewed the following Boeing Service Bulletins:

                    Table--Primary Service Bulletins
------------------------------------------------------------------------
                                  Describes the
                              following procedures
                                  for the trim
                                 actuator of the     And recommends that
    Boeing Alert Service           horizontal         those actions be
         Bulletin--                stabilizer              done--
                                (depending on the
                                    airplane
                                configuration)--
------------------------------------------------------------------------
737-27A1277, Revision 1,      Repetitive detailed   Within 6,400 flight
 dated July 25, 2007 (for      and general visual    hours or 18 months
 Model 737-600, -700, -700C,   inspections to        from the last
 -800, -900, and -900ER        detect                detailed
 series airplanes).            discrepancies         inspection,
                               (e.g., metal          whichever occurs
                               particles or          first, and
                               corrosion in          thereafter at
                               grease, damage,       intervals not to
                               cracks, corrosion,    exceed 6,400 flight
                               worn areas, grease    hours or 2 years,
                               leakage, and loose    whichever occurs
                               ball bearings) of     first.
                               the ball nut and
                               ballscrew.
                              Repetitive            Within 1,600 flight
                               lubrications of the   hours or 1 year
                               ball nut and          from the last
                               ballscrew.            lubrication,
                                                     whichever occurs
                                                     first, and
                                                     thereafter at
                                                     intervals not to
                                                     exceed 1,600 flight
                                                     hours or 1 year,
                                                     whichever occurs
                                                     first.
                              Repetitive repair/    Before the
                               overhaul.             accumulation of
                                                     25,000 flight hours
                                                     since the date of
                                                     issuance of the
                                                     original standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 25,000
                                                     flight hours since
                                                     the last overhaul
                                                     of the trim
                                                     actuator of the
                                                     horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     first, and
                                                     thereafter at
                                                     intervals not to
                                                     exceed 25,000
                                                     flight hours.

[[Page 22842]]

 
                              Installation of tube  Before the
                               retainers on the      accumulation of
                               ball nut.             25,000 flight hours
                                                     since the date of
                                                     issuance of the
                                                     original standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 25,000
                                                     flight hours since
                                                     the latest overhaul
                                                     of the trim
                                                     actuator of the
                                                     horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     later.
                              Applicable            Before further
                               corrective actions.   flight.
                               The corrective
                               actions include
                               repairing/replacing
                               discrepant parts.
737-27A1278, dated May 24,    Repetitive detailed   Within 2,000 or
 2007 (for Model 737-100, -    and general visual    4,000 flight hours
 200, -200C, -300, -400, and   inspections to        or 12 or 18 months
 -500 series airplanes).       detect                from the last
                               discrepancies         detailed
                               (e.g., metal          inspection,
                               particles or          whichever occurs
                               corrosion in          first, and
                               grease, damage,       thereafter at
                               cracks, corrosion,    intervals not to
                               worn areas, grease    exceed 2,000 or
                               leakage, and loose    4,000 flight hours
                               ball bearings) of     or 1 or 2 years,
                               the ball nut and      whichever occurs
                               ballscrew and         first (depending on
                               attachment (Gimbal)   the airplane
                               fittings.             configuration).
                              Repetitive            Within 500 or 2,000
                               lubrications of the   flight hours or 2
                               ball nut and          months or 1 year
                               ballscrew and         from the last
                               attachment (Gimbal)   lubrication,
                               fittings.             whichever occurs
                                                     first, and
                                                     thereafter at
                                                     intervals not to
                                                     exceed 500 or 2,000
                                                     flight hours or 2
                                                     months or 1 year,
                                                     whichever occurs
                                                     first (depending on
                                                     the airplane
                                                     configuration).
                              Repetitive repair/    Before the
                               overhaul.             accumulation of
                                                     20,000 flight hours
                                                     or 24,000 flight
                                                     hours since the
                                                     date of issuance of
                                                     the original
                                                     standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 20,000
                                                     flight hours or
                                                     24,000 flight hours
                                                     since the last
                                                     overhaul of the
                                                     trim actuator of
                                                     the horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     first (depending on
                                                     the airplane
                                                     configuration); and
                                                     thereafter at
                                                     intervals not to
                                                     exceed 20,000 or
                                                     25,000 flight
                                                     cycles (depending
                                                     on the airplane
                                                     configuration).
                              Installation of tube  Before the
                               retainers on the      accumulation of
                               ball nut.             24,000 flight hours
                                                     since the date of
                                                     issuance of the
                                                     original standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 24,000
                                                     flight hours since
                                                     the last overhaul
                                                     of the trim
                                                     actuator of the
                                                     horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     first.
                              Installation of a     Before the
                               grease fitting.       accumulation of
                                                     20,000 flight hours
                                                     since the date of
                                                     issuance of the
                                                     original standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 20,000
                                                     flight hours since
                                                     the last overhaul
                                                     of the trim
                                                     actuator of the
                                                     horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     first.
                              Installation of new   Before the
                               ball deflectors and   accumulation of
                               guide clamps for      24,000 flight hours
                               the ball return.      since the date of
                                                     issuance of the
                                                     original standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 24,000
                                                     flight hours since
                                                     the last overhaul
                                                     of the trim
                                                     actuator of the
                                                     horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     first.
                              Installation of new   Before the
                               return tube clamps.   accumulation of
                                                     20,000 flight hours
                                                     since the date of
                                                     issuance of the
                                                     original standard
                                                     airworthiness
                                                     certificate or the
                                                     date of issuance of
                                                     the original export
                                                     certificate of
                                                     airworthiness, or
                                                     within 20,000
                                                     flight hours since
                                                     the last overhaul
                                                     of the trim
                                                     actuator of the
                                                     horizontal
                                                     stabilizer,
                                                     whichever occurs
                                                     first.

[[Page 22843]]

 
                              Applicable            Before further
                               corrective actions.   flight.
                               The corrective
                               actions include
                               repairing/replacing
                               discrepant parts.
------------------------------------------------------------------------


                   Table.--Secondary Service Bulletins
------------------------------------------------------------------------
    Boeing Alert Service Bulletin--                Refers to--
------------------------------------------------------------------------
737-27A1277, Revision 1, dated July 25,  UMBRA CUSCINETTI Service
 2007 (for Model 737-600, -700, -700C, -  Bulletin 07322-27-01, dated
 800, -900, and -900ER series             December 21, 2004, as an
 airplanes).                              additional source of service
                                          information for installing
                                          tube retainers on the ball
                                          nut.
737-27A1278, dated May 24, 2007 (for     UMBRA CUSCINETTI Service
 Model 737-100, -200, -200C, -300, -      Bulletin 07322-27-01, dated
 400, and -500 series airplanes).         December 21, 2004, as an
                                          additional source of service
                                          information for installing
                                          tube retainers on the ball
                                          nut.
                                         Boeing 737 Service Bulletin 27-
                                          1046, Revision 1, dated April
                                          5, 1974, as an additional
                                          source of service information
                                          for installing a grease
                                          fitting.
                                         Linear Motion Service Bulletin
                                          7901708, Revision A, dated
                                          July 26, 2005, as an
                                          additional source of service
                                          information for installing new
                                          ball deflectors and guide
                                          clamps for the ball return.
                                         SKYTRONICS Service Bulletin
                                          93004, dated September 1,
                                          2005, as an additional source
                                          of service information for
                                          installing new return tube
                                          clamps.
------------------------------------------------------------------------

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(se) same type 
design(s). This proposed AD would require accomplishing the actions 
specified in the primary service bulletins described previously.

Clarification of Applicability of This AD

    Boeing has informed us that Model 737-900ER series airplanes were 
not specifically identified by model name in the Effectivity section of 
Boeing Alert Service Bulletin 737-27A1277. However, those airplanes are 
identified by variable numbers in the Effectivity section. Therefore, 
this AD refers to Model 737-900ER series airplanes where appropriate.

Costs of Compliance

    We estimate that this proposed AD would affect 1,602 Model 737 
airplanes of U.S. registry. The following table provides the estimated 
costs for U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Average                                          Number of
                                                                     labor                                             U.S.-
              Action \1\                      Work hours \1\        rate per    Parts       Cost per product \1\    registered       Fleet cost \1\
                                                                      hour                                           airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Detailed inspections..................  2 or 4...................        $80       None  $160 or $320, per               1,602  Between $256,320, and
                                                                                          inspection cycle.                      $512,640 per inspection
                                                                                                                                 cycle.
Lubrications..........................  1 or 3...................         80       None  $80 or $240, per                1,602  Between $128,160, and
                                                                                          lubrication cycle.                     $384,480 per
                                                                                                                                 lubrication cycle.
Repairs/overhauls.....................  40.......................         80       None  $3,200 per repair/              1,602  $5,126,400 per repair/
                                                                                          overhaul.                              overhaul cycle.
Installations.........................  Between 1 and 3..........         80     $2,200  Between $2,280 and $2,440       1,320  Between $3,009,600 and
                                                                                                                                 $3,220,800.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Depending on airplane configuration.

    The number of work hours, as indicated above, is presented as if 
the accomplishment of the actions in this proposed AD is to be 
conducted as new ``stand alone'' actions. However, in actual practice, 
the lubrications, detailed inspections, and overhauls are currently 
being done as part of normal airplane maintenance. The repair can be 
done coincidentally or in combination with the normally scheduled HSTA 
and ballscrew overhaul. Therefore, the actual number of necessary 
additional work hours will be minimal in many instances. Additionally, 
any costs associated with special airplane scheduling will be minimal.

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

[[Page 22844]]

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:

Boeing: Docket No. FAA-2008-0415; Directorate Identifier 2007-NM-
256-AD.

Comments Due Date

    (a) We must receive comments by June 12, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing airplanes identified in Table 1 of 
this AD, certificated in any category.

                         Table 1.--Applicability
------------------------------------------------------------------------
                                          As identified in Boeing Alert
             Boeing model--                     Service Bulletin--
------------------------------------------------------------------------
(1) 737-100, -200, -200C, -300, -400,    737-27A1278, dated May 24,
 and -500 series airplanes.               2007.
(2) 737-600, -700, -700C, -800, -900,    737-27A1277, Revision 1, dated
 and -900ER series airplanes.             July 25, 2007.
------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from a report of extensive corrosion of a 
ballscrew in the drive mechanism of the horizontal stabilizer trim 
actuator (HSTA). We are issuing this AD to prevent an undetected 
failure of the primary load path for the ballscrew in the drive 
mechanism of the HSTA and subsequent wear and failure of the 
secondary load path, which could lead to loss of control of the 
horizontal stabilizer and consequent loss of control of the 
airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Service Bulletins

    (f) The term ``service bulletin,'' as used in this AD, means the 
applicable service bulletins specified in Table 2 of this AD.

                       Table 2.--Service Bulletins
------------------------------------------------------------------------
    Boeing Alert Service Bulletin--                For model--
------------------------------------------------------------------------
(1) 737-27A1278, dated May 24, 2007....  737-100, -200, -200C, -300, -
                                          400, and -500 series
                                          airplanes.
(2) 737-27A1277, Revision 1, dated July  737-600, -700, -700C, -800, -
 25, 2007.                                900, and -900ER series
                                          airplanes.
------------------------------------------------------------------------


    Note 1: The service bulletins refer to UMBRA CUSCINETTI Service 
Bulletin 07322-27-01, dated December 21, 2004; Linear Motion Service 
Bulletin 7901708, Revision A, dated July 26, 2005; Boeing 737 
Service Bulletin 27-1046, Revision 1, dated April 5, 1974; and/or 
SKYTRONICS Service Bulletin 93004, dated September 1, 2005, as 
applicable, as additional sources of service information for 
accomplishing the specified actions.

Inspections, Lubrications, Repairs/Overhauls, and Applicable Corrective 
Actions

    (g) At the applicable compliance time and repeat intervals 
listed in Tables 1 and 2 of paragraph 1.E., ``Compliance,'' of the 
service bulletin, do the inspections, lubrications, repairs/
overhauls, installation(s), and applicable corrective actions by 
accomplishing all the applicable actions specified in the 
Accomplishment Instructions of the service bulletin; except as 
provided by paragraphs (g)(1) through (g)(3) of this AD.
    (1) Where paragraph 1.E., ``Compliance,'' of the service 
bulletin specifies an initial compliance time for accomplishing the 
initial inspection, lubrication, or repair/overhaul, this AD 
requires doing the applicable initial action(s) at the later of the 
times specified in paragraphs (g)(1)(i) and (g)(1)(ii) of this AD.
    (i) At the applicable compliance time specified in paragraph 
1.E., ``Compliance,'' of the service bulletin.
    (ii) Within the applicable compliance time specified in 
paragraph (g)(1)(ii)(A), (g)(1)(ii)(B), or (g)(1)(ii)(C) of this AD.
    (A) For the initial detailed inspection and lubrication: Within 
6 months after the effective date of this AD.
    (B) For the initial repair/overhaul: Within 12 months after the 
effective date of this AD.
    (C) For the installation(s): Within 12 months after the 
effective date of this AD.
    (2) Where Table 2 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-27A1277, Revision 1, dated July 25, 2007, 
specifies a compliance time of ``* * * within 25,000 Flight Hours 
since the latest horizontal stabilizer trim actuator (HSTA) Overhaul 
from the date of Revision 1 of this Service Bulletin * * *,'' this 
AD

[[Page 22845]]

requires compliance ``* * * within 25,000 flight hours since the 
last overhaul of the trim actuator of the horizontal stabilizer.''
    (3) Where Work Package 4, paragraphs 1.a., 2.a., and 3.a., of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-27A1278, dated May 24, 2007, specifies to identify the HSTA name 
plate ``* * * AS GIVEN IN SB 737-27A1278, WORK PACKAGE 3,'' this AD 
requires that identification `` * * * AS GIVEN IN SB 737-27A1278, 
WORK PACKAGE 4.''
    (4) Where Note (b) of Figures 7 through 9 of Boeing Alert 
Service Bulletin 737-27A1278, dated May 24, 2007, specifies to do a 
``* * * Backlash Inspection as given in AMM 27-41-81/606,'' this AD 
requires an ``* * * End Play Test as given in OHM 27-45-11 page 
701.''
    (h) Actions done before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 737-27A1277, dated 
July 21, 2005, are acceptable for compliance with the corresponding 
requirements of this AD.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
ATTN: Kelly McGuckin, Aerospace Engineer, Systems and Equipment 
Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 
Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6490; fax (425) 917-6590; has the authority to approve AMOCs for 
this AD, if requested using the procedures found in 14 CFR 39.19.
    (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 appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on April 17, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-9193 Filed 4-25-08; 8:45 am]
BILLING CODE 4910-13-P