[Federal Register Volume 60, Number 83 (Monday, May 1, 1995)]
[Proposed Rules]
[Pages 21054-21056]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-10585]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-26-AD]


Airworthiness Directives; Boeing Model 757 and 767 Series 
Airplanes Equipped With Sundstrand Ram Air Turbine (RAT)/Hydraulic 
Pumps

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 757 and 767 
series airplanes. This proposal would require replacement of the 
hydraulic pressure transfer tube of the ram air turbine (RAT) system 
with a new hose assembly. This proposal 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. The 
actions specified by the proposed AD are intended to prevent such 
cracking, which could result in 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: Comments must be received by June 26, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-26-AD, 1601 Lind Avenue, SW., 
[[Page 21055]] Renton, Washington 98055-4056. Comments may be inspected 
at this location between 9:00 a.m. and 3:00 p.m., Monday through 
Friday, except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-NM-26-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 95-NM-26-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports that, during two flight tests, the 
pressure transfer tube of the ram air turbine (RAT) cracked when the 
RAT was extended on a Model 767 series airplane. Investigation revealed 
that the cause of such cracking has been attributed to overload due to 
mishandling or improper installation of the pressure transfer tubes on 
the strut of the RAT system. Such overloads are likely to have occurred 
on other tubes because it is extremely difficult to shim the tubes 
properly. Cracking of the hydraulic pressure transfer tube of the RAT, 
if not corrected, could result in the loss of hydraulic fluid of the 
center system and the inability of the RAT to pressurize the center 
hydraulic system; this situation could lead to loss of all hydraulic 
system power in the event that power is lost in both engines.
    The subject RAT hydraulic pump and pressure transfer tube 
installations on Model 757 series airplanes are identical to those 
installed on Model 767 series airplanes. Therefore, both models may be 
subject to the same unsafe condition revealed on the Model 767.
    The FAA has reviewed and approved Boeing Alert Service Bulletin 
757-29A0046, dated October 6, 1994 (for Model 757 series airplanes), 
and Boeing Alert Service Bulletin 767-29A0077, dated October 6, 1994 
(for Model 767 series airplanes), which describe procedures for 
replacement of the hydraulic pressure transfer tube of the RAT system 
with a new hose assembly. Accomplishment of this replacement will 
prevent over stressing of the pressure line during installation.
    The RAT/hydraulic pumps addressed in these service bulletins are 
manufactured by Sundstrand. For Model 757 series airplanes, these pumps 
have part number 730814 series, serial numbers 0001 through 0735 
inclusive. For Model 767 series airplanes, these pumps have part number 
729548 series, serial numbers 0001 through 0620 inclusive.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require replacement of the hydraulic pressure 
transfer tube of the RAT system with a new hose assembly. The actions 
would be required to be accomplished in accordance with the alert 
service bulletins described previously.
    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 would be affected by this proposed AD, that 
it would take approximately 2 work hours per airplane to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
Required parts would be supplied by the manufacturer at no cost to the 
operators. Based on these figures, the total cost impact of the 
proposed 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 proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89. [[Page 21056]] 


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: 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 565 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 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) 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 cracking of the hydraulic pressure transfer 
tube of the ram air turbine (RAT), which could result in 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 (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; 
and Boeing Alert Service Bulletin 767-29A0077 references Sundstrand 
Service Bulletin 729548-29-14, dated November 3, 1994; 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 (for Model 757 
series airplanes); or Sundstrand Service Bulletin 729548-29-12, 
Revision 2, dated November 3, 1994 (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 
Secs. 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.

    Issued in Renton, Washington, on April 25, 1995.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-10585 Filed 4-28-95; 8:45 am]
BILLING CODE 4910-13-U