[Federal Register Volume 63, Number 226 (Tuesday, November 24, 1998)]
[Rules and Regulations]
[Pages 64857-64859]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-31325]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-157-AD; Amendment 39-10912; AD 97-09-15 R1]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,
and -500 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
[[Page 64858]]
ACTION: Final rule.
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SUMMARY: This amendment revises an existing airworthiness directive
(AD), applicable to all Boeing Model 737-100, -200, -300, -400, and -
500 series airplanes, that currently requires a one-time inspection to
determine the part number of the engage solenoid valve of the yaw
damper on the rudder power control unit, and replacement of the valve
with a valve having a different part number, if necessary. That AD was
prompted by a review of the design of the flight control systems on
Model 737 series airplanes. The actions specified by that AD are
intended to prevent sudden uncommanded yawing of the airplane due to
potential failures within the yaw damper system, and consequent injury
to passengers and crewmembers. This amendment makes certain editorial
changes to clarify the requirements of the existing AD.
EFFECTIVE DATE: December 29, 1998.
ADDRESSES: Information pertaining to this AD may be examined at the
Federal Aviation Administration (FAA), Transport Airplane Directorate,
Rules Docket, 1601 Lind Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Tin Truong, Aerospace Engineer, ANM-
130S, FAA, Transport Airplane Directorate, Seattle Aircraft
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 227-2764; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) by revising AD 97-09-15,
amendment 39-10011 (62 FR 24325, May 5, 1997), which is applicable to
all Boeing Model 737-100, -200, -300, -400, and -500 series airplanes,
was published in the Federal Register on November 13, 1997 (62 FR
60808). The action proposed to continue to require a one-time
inspection to determine the part number of the engage solenoid valve of
the yaw damper on the rudder power control unit (PCU), and replacement
of the valve with a valve having a different part number, if necessary.
The action also proposed to make certain editorial changes to clarify
the requirements of the existing AD.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Support for the Proposal
Two commenters support the proposal.
Request To Withdraw the Proposed AD
One commenter states that the proposed AD is unwarranted because it
is purely editorial rather than technical in nature and requests that
it be withdrawn. The commenter states that there is only one solenoid
valve of the part number identified in AD 97-09-15 that is used in the
yaw damper system, so it should be evident that the valve in question
is that of the PCU. In addition, the commenter states that, although
the vendor part numbers are not contained in AD 97-09-15, they are easy
to convert to the appropriate vendor numbers from cross references
located in the Illustrated Parts Catalog (IPC) and the Component
Maintenance Manual (CMM). The commenter also states that, although the
aircraft maintenance manual chapter referenced in AD 97-09-15 is
technically incorrect for certain Model 737-100 and -200 series
airplanes, the obvious intent of AD 97-09-15 is to ensure that the
specified solenoid valve is installed, and the procedures for
replacement should obviously be those applicable for routine valve
replacement. The commenter also notes that AD 97-14-04, amendment 39-
10061 (62 FR 35068, June 30, 1997), which requires modification of the
rudder PCU, will drive the inspection to be done in a shop environment,
which would then require the use of the rudder PCU CMM, rather than the
aircraft maintenance manual, for this inspection. Further, the
commenter states that although the vendor name labeled on the affected
parts may vary, the part number, function, and location do not.
The FAA does not concur that the revision is unwarranted. The FAA
agrees that there is only one solenoid valve of the part number
identified in AD 97-09-15 that is used in the yaw damper system;
however, this final rule is clearer and will prevent confusion. In
addition, it is not appropriate to determine the vendor part number
using the IPC because the IPC is not an FAA-approved document and its
use does not ensure correlation of the appropriate part number.
Therefore, it is necessary to identify all Boeing and vendor part
numbers in the AD to ensure appropriate installation. Also, the FAA
does not agree with the commenter that maintenance manual references in
AD 97-09-15 are sufficient to ensure the use of proper maintenance
procedures for valve installation. The FAA also does not agree with the
comment that compliance with AD 97-14-04 will ensure that the required
inspection will be done only in a shop environment. This final rule
allows operators the flexibility to perform this inspection on the
airplane or in the shop. The FAA agrees that, although the vendor name
labeled on the affected parts may vary, the part number, function, and
location do not; however, this final rule is clearer and will prevent
confusion.
Request To Revise Corrective Action
One commenter requests that the requirement to replace a suspect
engage solenoid valve prior to further flight be deleted. The commenter
states that this requirement is too restrictive and could lead to
unnecessary airplane grounding if a valve having the appropriate part
number is unavailable. The FAA does not concur. In developing an
appropriate compliance time for this action, the FAA considered not
only the degree of urgency associated with addressing the subject
unsafe condition, but the availability of required parts and the
practical aspect of installing the required modification within an
interval of time that parallels normal scheduled maintenance for the
majority of affected operators. The manufacturer has advised that an
ample number of required parts will be available for modification of
the U.S. fleet within the specified compliance period. No change to the
rule is necessary.
Request To Include All Applicable Maintenance Manual Chapters
One commenter states that Boeing Maintenance Manual Chapter 22-12-
21 is applicable for some operators of Model 737-100 and -200 series
airplanes and that use of the procedures contained in Chapter 22-12-21
should be allowed to accomplish the actions in this AD. The FAA concurs
and has revised paragraph (a) of the final rule accordingly.
Request for Credit of Previously Accomplished Work
One commenter requests that, because the proposed revisions to the
AD are editorial in nature, a statement be added to the AD to state
that work already accomplished on any airplanes affected by AD 97-09-15
should not require additional action. The commenter also requests that
all previously approved alternative methods of compliance should remain
valid and in effect.
The FAA agrees with the commenter that this AD does not change the
required actions of AD 97-09-15 and that any airplanes inspected and
modified in accordance with AD 97-09-15 would not require additional
action. However, operators are always given credit for work previously
performed in accordance with the existing AD by means of the phrase in
the compliance
[[Page 64859]]
section of the AD that states, ``Required * * * unless accomplished
previously.'' Further, no alternative methods of compliance have been
approved for the AD 97-09-15. Therefore, no change to the rule is
necessary in this regard.
Conclusion
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the change previously
described. The FAA has determined that this change will neither
increase the economic burden on any operator nor increase the scope of
the AD.
Cost Impact
There are approximately 2,675 Boeing Model 737 series airplanes of
the affected design in the worldwide fleet. The FAA estimates that
1,091 airplanes of U.S. registry will be affected by this AD.
It will take approximately 1 work hour per airplane to accomplish
the required one-time inspection, at an average labor rate of $60 per
work hour. Based on these figures, the cost impact of the inspection
required by this AD on U.S. operators is estimated to be $65,460, or
$60 per airplane. The requirements of this AD will add no new costs to
affected operators.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the requirements of this AD
action, and that no operator would accomplish those actions in the
future if this AD were not adopted.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under 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. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (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. Section 39.13 is amended by removing amendment 39-10011 (62 FR
24325, May 5, 1997), and by adding a new airworthiness directive (AD),
amendment 39-10912, to read as follows:
97-09-15 R1 Boeing: Amendment 39-10912. Docket 97-NM-157-AD. Revises
AD 97-09-15, Amendment 39-10011.
Applicability: All Model 737-100, -200, -300, -400, and -500
series airplanes; certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (b) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent sudden uncommanded yawing of the airplane due to
potential failures within the yaw damper system, and consequent
injury to passengers and crewmembers, accomplish the following:
(a) Perform a one-time inspection of the engage solenoid valve
of the yaw damper on the rudder power control unit (PCU) to
determine the part number (P/N) of the valve. If any valve having
Parker P/N 59600-5011 (Boeing P/N 10-60811-9), Parker P/N 59600-5007
(Boeing P/N 10-60811-3), or Parker P/N 59600-5003 (Boeing P/N 10-
60811-1) is installed, prior to further flight, replace it with a
valve having Parker P/N 881600-1001 (Boeing P/N 10-60811-13), Sterer
P/N 45080-1 (Boeing P/N 10-60811-8), or Sterer P/N 45080 (Boeing P/N
10-60811-3). Accomplish the actions in accordance with procedures
specified in Chapters 22-11-61 or 22-12-21 (for Model 737-100 and -
200 series airplanes), as applicable; or Chapter 22-12-21 (for Model
737-300, -400, and -500 series airplanes) of the Boeing Maintenance
Manual, as applicable. Accomplish the inspection at the earlier of
the times specified in paragraphs (a)(1) and (a)(2) of this AD.
(1) Within 5 years or 15,000 flight hours after June 9, 1997
(the effective date of AD 97-09-15, amendment 39-10011), whichever
occurs first.
(2) At the next time the PCU is sent to a repair facility.
Note 2: Boeing In-Service Activities Report 95-03-2725-10, dated
February 16, 1995 (for Model 737-100 and -200 series airplanes), or
95-04-2725-10, dated February 24, 1995 (for Model 737-300, -400, and
-500 series airplanes), provides additional information concerning
interchangeability of solenoid valve part numbers.
Note 3: Operators should note that, as specified in paragraph
(a) of this AD, both the Parker and Sterer P/N's have the same
Boeing P/N (10-60811-3). If, upon inspection, Boeing P/N 10-60811-3
is found to be installed, operators must ascertain the vendor P/N.
Parts having Boeing P/N 10-60811-3 and Parker P/N 59600-5007 must be
replaced and are not considered to be acceptable replacement parts.
In addition, some engage solenoid valves may be labeled with only
the name ``Bertea,'' rather than ``Parker'' or ``Parker-Bertea.''
(b) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Seattle Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Seattle, ACO.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(c) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(d) This amendment becomes effective on December 29, 1998.
Issued in Renton, Washington, on November 18, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-31325 Filed 11-23-98; 8:45 am]
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