[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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