[Federal Register Volume 60, Number 174 (Friday, September 8, 1995)]
[Rules and Regulations]
[Pages 46763-46765]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-20857]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-26-AD; Amendment 39-9350; AD 95-18-02]
Airworthiness Directives; Boeing Model 757 and 767 Series
Airplanes Equipped With Sundstrand Ram Air Turbine (RAT)/Hydraulic
Pumps
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 757 and 767 series airplanes, that
requires replacement of the hydraulic pressure transfer tube of the ram
air turbine (RAT) system with a new hose assembly. This amendment is
prompted by reports that, during flight tests, the hydraulic pressure
transfer tube of the RAT cracked when the RAT was extended on a Model
767 series airplane due to overload of the hydraulic transfer tube. The
actions specified by this AD are intended to prevent such overload,
which could result in cracking of the hydraulic transfer tube. Such
cracking subsequently could lead to the loss of hydraulic fluid of the
center system and the inability of the RAT to pressurize the center
system; this situation could lead to loss of all hydraulic system power
in the event that power is lost in both engines.
DATES: Effective October 10, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of October 10, 1995.
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: Kathi Ishimaru, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington, 98055-4056; telephone (206) 227-2674; 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 757 and 767
series airplanes was published in the Federal Register on May 1, 1995
(60 FR 21054). That action proposed to require replacement of the
hydraulic pressure transfer tube of the ram air turbine (RAT) system
with a new hose assembly.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
One commenter supports the proposed rule.
One commenter notes that the description of the cause of the unsafe
condition that appeared in the Discussion section of the preamble to
the notice states that ``* * * cracking has been attributed to overload
due to mishandling or improper installation of the pressure transfer
tubes on the strut of the RAT system.'' The commenter states that this
description is inaccurate, since the overload condition could only
occur as a result of maintenance action on in-service airplanes. The
commenter suggests that a more accurate description would be ``* * *
cracking has been attributed to overload of the pressure transfer tube
due to mishandling or improper installation during in-service RAT
maintenance.'' The FAA concurs that the commenter's wording is more
accurate; however, since the Discussion section is not restated in this
final rule, no change to the final rule is necessary.
This commenter also provides further clarification of the unsafe
condition described throughout the notice. That description states that
``cracking of the hydraulic transfer tube, if not corrected, could
result in loss of hydraulic fluid * * * '' The commenter states that a
more complete description of the unsafe condition would be ``* * *
overload of the hydraulic transfer tube, if not corrected, may cause
the tube to crack and could result in loss of hydraulic fluid * * * ''
The FAA concurs and has revised all references to the unsafe condition
accordingly throughout this final rule.
The same commenter further notes that the Discussion section of the
preamble to the notice states that ``such overloads are likely to have
occurred on other tubes * * * '' The commenter states that, since only
one operator has reported cracking on two pressure transfer tubes, it
does not provide a basis to conclude that overload is ``likely'' to
occur on other airplanes. The commenter suggests that a more accurate
description of this situation would be, ``such overloads may have
occurred on other tubes * * * '' Further, the commenter states that
testing has demonstrated that the RAT transfer tubes performed
acceptably during an in-flight RAT deployment when shimmed in
accordance with the maintenance manual. The FAA has reviewed the
relevant data currently available. The FAA finds no basis to support
the commenter's suggestion that the RAT transfer tubes perform
acceptably when shimmed. In fact, the testing showed abnormally high
stresses in the tube when the tube was shimmed in accordance with the
maintenance manual. However, the FAA concurs that the commenter's
suggested wording relative to the fact that overload conditions ``may
have occurred'' is more accurate. Since the Discussion section is not
restated in this final rule, no change to the final rule is necessary.
Additionally, this commenter points out a statement that appeared
in the Discussion section of the preamble to the notice that reads,
``since an unsafe condition has been identified that is likely to exist
* * * '' The commenter suggests that this phrase would be more accurate
if it were changed to read, ``since an unsafe condition has been
identified that may exist * * *'' The FAA does not concur. The phrasing
used in that particular statement in the preamble is not accidental.
Part 39.1, ``Applicability,'' of the Federal Aviation Regulations (FAR)
(14 CFR 39.1) states:
``This part prescribes airworthiness directives that apply to
aircraft * * * when--
(a) An unsafe condition exists in a product; and
(b) That condition is likely to exist or develop in other products
of the same type design.''
Therefore, the finding that the condition ``is likely to exist or
develop'' is necessary to ensure that the AD falls within the scope of
part 39; its absence would arguably subject the FAA to legal challenge
for inappropriately using the AD process to issue rules that do not
meet the criteria for AD's. While it is understandable that a
manufacturer
[[Page 46764]]
would like to minimize any adverse implications regarding the safety of
its products, the FAA reiterates that the purpose of an AD is to
correct an identified unsafe condition in aircraft, regardless of where
it is or what it is caused by. In essence, the AD serves to protect the
flying public from the consequences of the unsafe condition. The AD
also serves to protect the manufacturer from the liability that would
be faced should the unsafe condition not be corrected.
Two commenters request that the compliance time be extended from
the proposed 24 months to 36 months. One of these commenters states
that such an extension will allow operators to accomplish the
replacement during a regularly scheduled heavy maintenance visit and
will allow time for procurement of additional parts.
The FAA does not concur with the commenters' request to extend the
compliance time. 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 accomplishing the required
replacement 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 proposed compliance
period. Further, the FAA estimates that it would take approximately 2
work hours per airplane to accomplish the replacement; therefore, the
FAA has determined that a heavy maintenance visit is not required to
accomplish the replacement. However, under the provisions of paragraph
(b) of the final rule, the FAA may approve requests for adjustments to
the compliance time if data are presented to justify such an
adjustment.
One commenter requests that the proposed rule be revised to cite
the latest revision of Boeing Alert Service Bulletin 767-29A0077. The
FAA concurs. Since the issuance of the proposed rule, the FAA has
reviewed and approved Revision 1, dated June 8, 1995, of that Boeing
alert service bulletin. This revised service bulletin is essentially
identical to the original version; the only relevant change in Revision
1 is a revision to the effectivity listing that removes the airplane
having serial number 565. The FAA has revised paragraph (a) of the
final rule to reflect the latest revision to the alert service bulletin
as an additional source of service information. The FAA has also
revised the applicability of the final rule to remove serial number 565
from those Model 767 series airplanes that are subject to the AD.
The same commenter requests that NOTE 3 of the proposal be revised
to cite the latest revision of Sundstrand Service Bulletins 730814-29-9
and 729548-29-12. The FAA concurs. The FAA has reviewed and approved
Sundstrand Service Bulletin 729548-29-12, Revision 3, dated March 31,
1995; and Sundstrand Service Bulletin 730814-29-9, Revision 2, dated
March 31, 1995. These revised service bulletins are essentially
identical to the corresponding earlier versions, but contain certain
minor editorial changes. The FAA has revised NOTE 3 of the final rule
to reflect the latest revision to the service bulletins as additional
sources of service information.
Since issuance of the notice, the FAA also has reviewed and
approved Sundstrand Service Bulletin 729548-29-14, Revision 1, dated
May 3, 1995, and Sundstrand Service Bulletin 730814-29-11, Revision 1,
dated May 3, 1995. These revised service bulletins are essentially
identical to the corresponding earlier versions, but contain certain
minor editorial changes. The FAA has revised NOTE 2 of the final rule
to reflect these latest revisions to those service bulletins as
additional sources of service information.
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
increase the economic burden on any operator nor increase the scope of
the AD.
There are approximately 1,215 Model 757 and 767 series airplanes of
the affected design in the worldwide fleet. The FAA estimates that 582
airplanes of U.S. registry will be affected by this AD, that it will
take approximately 2 work hours per airplane to accomplish the required
actions, and that the average labor rate is $60 per work hour. Required
parts will be supplied by the manufacturer at no cost to the operators.
Based on these figures, the total cost impact of the AD on U.S.
operators is estimated to be $69,840, or $120 per airplane.
The total 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.
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), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
95-18-02 Boeing: Amendment 39-9350. Docket 95-NM-26-AD.
Applicability: Model 757 series airplanes having line positions
1 through 650 inclusive, and equipped with Sundstrand ram air
turbine (RAT)/hydraulic pumps having part number (P/N) 730814
series, serial numbers 0001 through 0735 inclusive; and Model 767
series airplanes having line positions 1 through 564 inclusive, and
equipped with Sundstrand RAT/hydraulic pumps having P/N 729548
series, serial numbers 0001 through 0620 inclusive; 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
[[Page 46765]]
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 use the
authority provided in paragraph (b) of this AD to request approval
from the FAA. This approval may address either no action, if the
current configuration eliminates the unsafe condition; or different
actions necessary to address the unsafe condition described in this
AD. Such a request should include an assessment of the effect of the
changed configuration on the unsafe condition addressed by this AD.
In no case does the presence of any modification, alteration, or
repair remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent overload of the hydraulic pressure transfer tube,
which could result in cracking of the tube of the ram air turbine
(RAT), and subsequently could lead to the loss of all center systems
hydraulic fluid and the inability of the RAT to pressurize the
center hydraulic system, accomplish the following:
(a) Within 24 months after the effective date of this AD,
replace the hydraulic pressure transfer tube of the RAT system with
a new hose assembly, in accordance with Boeing Alert Service
Bulletin 757-29A0046, dated October 6, 1994 (for Model 757 series
airplanes); or Boeing Alert Service Bulletin 767-29A0077, dated
October 6, 1994, or Revision 1, dated June 8, 1995 (for Model 767
series airplanes); as applicable.
Note 2: Boeing Alert Service Bulletin 757-29A0046 references
Sundstrand Service Bulletin 730814-29-11, dated November 3, 1994, or
Revision 1, dated May 3, 1995; and Boeing Alert Service Bulletin
767-29A0077 references Sundstrand Service Bulletin 729548-29-14,
dated November 3, 1994, or Revision 1, dated May 3, 1995; as
additional sources of service information for procedures to replace
the pressure tube.
Note 3: Modification of the hydraulic pressure transfer tube of
the RAT system in accordance with Sundstrand Service Bulletin
730814-29-9, Revision 1, dated November 3, 1994, or Revision 2,
dated March 31, 1995 (for Model 757 series airplanes); or Sundstrand
Service Bulletin 729548-29-12, Revision 2, dated November 3, 1994,
or Revision 3, dated March 31, 1995 (for Model 767 series
airplanes); is considered acceptable for compliance with the
modification requirements of paragraph (a) of this AD.
(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) The replacement shall be done in accordance with Boeing
Alert Service Bulletin 757-29A0046, dated October 6, 1994 (for Model
757 series airplanes); or in accordance with Boeing Alert Service
Bulletin 767-29A0077, dated October 6, 1994, or Boeing Alert Service
Bulletin 767-29A0077, Revision 1, dated June 8, 1995 (for Model 767
series airplanes); as applicable. 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.
(e) This amendment becomes effective on October 10, 1995.
Issued in Renton, Washington, on August 17, 1995.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-20857 Filed 9-7-95; 8:45 am]
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