[Federal Register: April 28, 2008 (Volume 73, Number 82)]
[Proposed Rules]
[Page 22840-22845]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr28ap08-17]
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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).
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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