[Federal Register Volume 61, Number 216 (Wednesday, November 6, 1996)]
[Rules and Regulations]
[Pages 57313-57315]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-27645]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-36-AD; Amendment 39-9799; AD 96-22-11]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100 and -200 Series
Airplanes, and Model 747-100, -200, -300, and -SP Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to certain Boeing Model 737 and 747 series airplanes, that
requires replacement of Waterman hydraulic fuse assemblies with
modified assemblies. This amendment is prompted by reports of failure
of hydraulic system A and the standby system, due to corrosion on the
magnesium piston of the hydraulic fuse and consequent failure of the
fuse to close sufficiently to prevent the loss of hydraulic fluid from
the system. The actions specified by this AD are intended to prevent
such failure of the fuse, which could result in the failure of one or
more hydraulic systems and resultant reduced controllability of the
airplane.
DATES: Effective December 11, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 11, 1996.
ADDRESSES: The service information referenced in this AD may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the Federal
Aviation Administration (FAA), Transport Airplane Directorate, Rules
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of
the Federal Register, 800 North Capitol Street, NW., suite 700,
Washington, DC.
FOR FURTHER INFORMATION CONTACT: Kenneth W. Frey, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue, SW., Renton, Washington;
telephone (206) 227-2673; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to certain Boeing Model 737 and 747
series airplanes was published in the Federal Register on April 30,
1996 (61 FR 18997). That action proposed to require replacement of
Waterman hydraulic fuse assemblies with modified assemblies.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Request To Extend Compliance Time
The Air Transport Association (ATA) of America, on behalf of
several of its members, requests that the proposed compliance time be
extended from 3,000 flight hours to 24 months. The commenter indicates
that accomplishment of the modification is dependent upon the ability
of an outside vendor to rework the fuse assemblies and return them to
the operator. The commenter states that the proposed compliance time
may be insufficient for the vendor to provide this service.
Additionally, two ATA members indicate that no fuse failures have
occurred within their fleets.
Another commenter suggests that, since the compliance time would be
insufficient to send the assemblies to a vendor for modification,
operators of affected Model 747 series airplanes should be required to
perform an initial and periodic inspections of the Waterman hydraulic
fuses having part number G905-120 in accordance with the Airplane
Maintenance Manual to confirm the function of the fuses until they can
be replaced with PneuDraulics fuses having part number 6105.
The FAA concurs that the compliance time may be extended. In
developing an appropriate compliance time for this AD action, the FAA
considered not only the degree of urgency associated with addressing
the subject unsafe condition, but the practical aspect of sending the
fuse assemblies to an outside vendor for accomplishment of the
modification. The FAA has considered the information presented by the
commenters as to the turnaround time for accomplishment of the
modification. In light of this information and the number of fuses that
may need to be modified, the FAA agrees that the compliance time should
be extended. The FAA has determined that extending the compliance time
from the proposed 3,000 flight hours to 24 months will provide an
acceptable level of safety without the need for interim inspections (as
suggested by one of the commenters). Paragraphs (a) and (b) of the
final rule have been revised accordingly.
Request To Add a Note to the AD
One commenter requests that the FAA add a note to the proposal to
specify that availability of replacement fuses should be considered
when scheduling compliance with the AD, and to advise operators to
begin accomplishing the requirements of the AD as soon as the final
rule is issued. The commenter expresses concern that the lead time for
obtaining replacement fuses may be inadequate and that the proposed
compliance time may not be met unless operators place orders for these
fuses during the early stages of the compliance period.
The FAA does not concur that a note should be added to the final
rule. The FAA acknowledges that accomplishment of the replacement is
dependent upon the ability of outside vendors to manufacture and rework
rotable units within a certain time frame. However, as explained
previously, the FAA has extended the compliance time for accomplishing
the replacement from 3,000 flight hours to 24 months. The FAA finds
that this extension should allow sufficient time
[[Page 57314]]
for operators to obtain replacement parts within the compliance time
specified in this final rule.
Request To Allow Additional Method of Compliance
One commenter requests that the FAA revise the proposal to cite
Gould/Waterman Service Bulletin G905-40-8, dated July 15, 1981, as an
additional method of complying with the requirements of the AD. The
Gould/Waterman service bulletin describes procedures for modifying the
G905-120 Type II fuse by replacing the magnesium piston with an
aluminum piston and by revising the part number to G9051-120. The
commenter indicates that accomplishing the Gould/Waterman service
bulletin is equivalent to replacing the fuse with a PneuDraulics fuse.
A second commenter requests that the FAA revise the proposed rule
to include replacement of Waterman fuses having part number G905-120
with Waterman fuses having part number G9051-120, in accordance with
the Gould/Waterman service bulletin, as an acceptable method of
compliance with the AD for Model 747 series airplanes. This commenter
indicates that the change in piston subassembly materials from
magnesium to an all aluminum design eliminates corrosion problems
related to the G905-8-120 model fuse. The commenter adds that many
operators have replaced G905-120 fuses with the replacements identified
in the Gould/Waterman service bulletin.
The FAA does not concur that the final rule should be revised to
cite the Gould/Waterman service bulletin or to specify that the G9051-
120 Waterman fuse is an acceptable replacement part. The FAA has not
approved the Gould/Waterman service bulletin as an additional method of
complying with the AD. The FAA finds that it is inappropriate to delay
the issuance of this final rule to provide time for review and approval
of the Gould/Waterman service bulletin. However, should an operator of
an affected Model 747 series airplane wish to accomplish the
requirements of this AD by replacing Waterman fuses having part number
G905-120 with Waterman fuses having part number G9051-120, that
operator should submit a request for approval of such replacement, in
accordance with the provisions of paragraph (d) of this final rule.
Request To Disallow Use of Certain Replacement Fuses
One commenter asks that the FAA disapprove any request from an
operator of a Model 747 series airplane to accomplish the proposed
replacement using a modified fuse in lieu of a PneuDraulics fuse having
part number 6105. The commenter explains that one of the primary
reasons for replacing the Waterman fuses is that the fuse would not
reset once pressure was balanced in the system. The commenter indicates
that the airplane manufacturer prefers to install PneuDraulics fuses
having part number 6105 in the hydraulics systems of Model 747 series
airplanes. The commenter adds that replacement of Waterman hydraulic
fuse pistons with modified fuse pistons does not incorporate the use of
the latest technology.
The FAA concurs partially. The FAA points out that paragraph (b) of
this final rule requires that operators of Model 747 series airplanes
use PneuDraulics fuse assemblies having part number 6105 as replacement
parts. However, as explained previously, if an operator of these
airplanes wishes to request approval of the use of other airworthy
replacement parts (including modified parts) in lieu of the
PneuDraulics part, the FAA would consider such a request provided that
data is submitted to substantiate approval of that request.
Request for Clarification of Fuse Locations and Numbers
One commenter requests that the FAA provide the exact position and
number of fuses that require replacement. The commenter notes that the
preamble of the proposed rule indicates there are eight affected fuses
installed on each Model 737 series airplane. However, the commenter's
records show that there are only four possible locations for the
affected fuses to be installed on those airplanes.
The FAA concurs that clarification is necessary. A total of eight
affected fuses (four wheel brake fuses, one auto brake fuse, one
leading edge fuse, and two thrust reverser fuses) are installed in the
standby leading edge system, the brake system, and the standby thrust
reverser system of Model 737 series airplanes. Further, a total of 24
brake fuses are installed in the normal and reserve brake systems on
Model 747 series airplanes. The FAA finds that no change to the final
rule is necessary in response to the commenter's request.
Revision to Service Letter Citation
The FAA has revised paragraph (a) of the final rule to indicate
that Boeing Service Letter 737-SL-29-21, dated December 16, 1982,
includes Attachments 1, 2, and 3, dated April 15, 1982.
Revision to Cost Impact Information
Since the issuance of the proposed rule, a vendor has advised the
FAA that the cost for required replacement parts for Boeing Model 747
series airplanes will be $31,200 per airplane ($1,300 per fuse; 24
fuses per airplane). In light of this, the FAA has revised the cost
impact information, below, to reflect this change.
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 changes previously
described. The FAA has determined that these changes will neither
significantly increase the economic burden on any operator nor increase
the scope of the AD.
Cost Impact
There are approximately 1,145 Boeing Model 737 series airplanes and
727 Boeing Model 747 series airplanes of the affected design in the
worldwide fleet.
The FAA estimates that 421 Boeing Model 737 series airplanes of
U.S. registry will be affected by this AD, that it will take
approximately 16 work hours per airplane (8 fuses per airplane; 2 work
hours per fuse) to accomplish the required actions, and that the
average labor rate is $60 per work hour. Required parts that are
modified by the vendor will be provided at no cost to operators. Based
on these figures, the cost impact of the AD on U.S. operators of Model
737 series airplanes is estimated to be $404,160, or $960 per airplane.
The FAA estimates that 208 Boeing Model 747 series airplanes of
U.S. registry will be affected by this AD, that it will take
approximately 48 work hours per airplane (24 fuses per airplane; 2 work
hours per fuse) to accomplish the required actions, and that the
average labor rate is $60 per work hour. The cost for required parts
will be $31,200 per airplane ($1,300 per fuse; 24 fuses per airplane).
Required parts that are modified by the vendor will be provided at no
cost to operators. Based on these figures, the cost impact of the AD on
U.S. operators of Model 747 series airplanes is estimated to be
$7,088,640, or $34,080 per airplane.
The cost impact figures discussed above are 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.
[[Page 57315]]
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, Incorporation by
reference, 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 adding the following new
airworthiness directive:
96-22-11 Boeing: Amendment 39-9799. Docket 96-NM-36-AD.
Applicability: Model 737-100 and -200 series airplanes, as
identified in Boeing Service Letter 737-SL-29-21, dated December 16,
1982; and Model 747-100, -200, -300, and -SP series airplanes, as
identified in Boeing Service Letter 747-SL-32-19, dated January 16,
1980; 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 (d) 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 failure of the hydraulic fuse, which could result in
the failure of one or more hydraulic systems and resultant reduced
controllability of the airplane, accomplish the following:
(a) For Model 737-100 and -200 series airplanes: Within 24
months after the effective date of this AD, replace Waterman
hydraulic fuse assemblies, having Waterman part number (P/N) G838-8-
40, G838-8-60, or G838-8-160, with modified assemblies having P/N
G8381-8-40, G8381-8-60, or G8381-8-160, respectively; or with a
PneuDraulics fuse specified in Boeing Service Letter 737-SL-29-21,
dated December 16, 1982, including Attachments 1, 2, and 3, dated
April 15, 1982. Accomplish the replacement in accordance with the
service letter.
Note 2: The Boeing service letter references Imperial Clevite,
Inc., Service Bulletins G838-80-4, G838-80-5, and G838-80-6, all
dated April 15, 1982, as additional sources of service information
for accomplishment of the replacement.
(b) For Model 747-100, -200, -300, and -SP series airplanes:
Within 24 months after the effective date of this AD, replace
Waterman hydraulic fuse assemblies, having Waterman P/N G905-120,
with PneuDraulics assemblies having PneuDraulics P/N 6105, in
accordance with Boeing Service Letter 747-SL-32-19, dated January
16, 1980.
(c) As of the effective date of this AD, no person shall install
on any airplane Waterman hydraulic fuse assemblies having Waterman
P/N G838-8-40, G838-8-60, G838-8-160, or G905-120.
(d) 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(e) 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.
(f) The replacement shall be done in accordance with the
following Boeing service letters, as applicable, which include the
specified list of effective pages:
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Service letter referenced and Revision level
date Page No. shown on page Date shown on page
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737-SL-29-21, December 16, 1982.. 1, 2.................... ................... December 16, 1982.
Attachment 1, Page 1, 2; ................... April 15, 1982.
Attachment 2, Page 1,
2; Attachment 3, Page
1, 2.
747-SL-32-19, January 16, 1980... 1, 2.................... ................... January 16, 1980.
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This incorporation by reference was approved by the Director of
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR
part 51. Copies may be obtained from Boeing Commercial Airplane
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be
inspected at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington; or at the Office of the Federal
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(g) This amendment becomes effective on December 11, 1996.
Issued in Renton, Washington, on October 22, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-27645 Filed 11-5-96; 8:45 am]
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