[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:

----------------------------------------------------------------------------------------------------------------
  Service letter referenced and                                 Revision level                                  
               date                        Page No.             shown on page           Date shown on page      
----------------------------------------------------------------------------------------------------------------
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]
BILLING CODE 4910-13-U