[Federal Register Volume 61, Number 124 (Wednesday, June 26, 1996)]
[Proposed Rules]
[Pages 33050-33052]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-16243]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-226-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 747 
and 767 series

[[Page 33051]]

airplanes, that currently requires inspection of the door opening 
thrusters and door opening/snubbing actuators for proper oil quantity, 
and modification of the off-wing compartment latching assemblies. This 
action would add a requirement for replacement of the currently 
installed door opening thrusters with new, improved thrusters for Model 
747 series airplanes. This action also would remove Model 767 series 
airplanes from the applicability of the existing AD. This proposal is 
prompted by reports indicating that the requirements of the existing AD 
do not adequately preclude leakage of fluid from the actuators. The 
actions specified by the proposed AD are intended to prevent such 
leakage, which could result in failure of the escape slide to deploy; 
such failure could delay and possibly jeopardize the successful 
emergency evacuation of an airplane.

DATES: Comments must be received by August 5, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-226-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 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: Gregory L. Schneider, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington; 
telephone (206) 227-2028; 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-226-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-226-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On July 15, 1992, the FAA issued AD 92-16-17, amendment 39-8327 (57 
FR 47987, October 21, 1992), which is applicable to certain Model 747 
and 767 series airplanes. That AD requires repetitive inspections 
(weighing program) of the door opening thrusters and door opening/
snubbing actuators for proper oil quantity, and modification of the 
off-wing compartment latching assemblies. That action was prompted by 
reports of failure of the off-wing escape slide system to deploy when 
commanded. The requirements of that AD are intended to prevent such 
failure, which could delay and possibly jeopardize the successful 
emergency evacuation of an airplane.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA received a report from an 
operator of Model 767 series airplanes indicating that several 
actuators leaked following accomplishment of the modification required 
by AD 92-16-17. Consequently, the FAA determined that the modification 
requirements of that AD do not adequately preclude leakage from the 
actuators. Additionally, the operator reported that, during inspections 
(weighing program) of the actuators, the weight of several actuators 
increased from the original weight measured during the initial 
inspection required by AD 92-16-17. Therefore, the FAA determined that 
the inspection requirements of AD 92-16-17 cannot reliably determine 
the fluid level of these actuators.
    Subsequently, the manufacturer developed a new, improved actuator 
for Model 767 series airplanes. On April 10, 1995, the FAA issued AD 
95-08-11, amendment 39-9200 (60 FR 20013, April 24, 1995), to require 
replacement of the currently installed door opening actuators of the 
off-wing emergency escape system on Model 767 series airplanes with 
new, improved actuators. Accomplishment of that replacement constitutes 
terminating action for the repetitive inspections (weighing program) of 
the door opening/snubbing actuators for those airplanes. The FAA 
indicated in AD 95-08-11 that it was considering a separate rulemaking 
action to remove the requirements for Model 767 series airplanes from 
AD 92-16-17.
    The door opening thrusters installed on Model 747 series airplanes 
are similar in design to the door opening/snubbing actuators installed 
on Model 767 series airplanes in that both require a small quantity of 
oil to operate, and both have a tendency to leak oil from the chamber. 
Such leakage can result in failure of an actuator or thruster.

Explanation of Relevant Service Information

    Boeing has issued Service Bulletin 747-25-3073, dated September 21, 
1995, which describes procedures for replacement of existing door 
opening thrusters on Model 747 series airplanes with new, improved 
thrusters. Since the new, improved thruster is not fluid filled, 
accomplishment of the replacement eliminates the need for inspections 
of the door opening thrusters and door opening/snubbing actuators for 
proper oil quantity.

Explanation of Requirements of Proposed Rule

    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 supersede AD 92-16-17 to continue to require 
repetitive inspections of the door opening thrusters and door opening/
snubbing actuators for proper oil quantity, and modification of the 
off-wing compartment latching assemblies for Model 747 series 
airplanes. For those airplanes, this proposed AD would add a 
requirement for replacement of existing door opening thrusters with 
new, improved thrusters. Accomplishment of the replacement constitutes 
terminating action for the repetitive inspections. The actions would be 
required to be accomplished

[[Page 33052]]

in accordance with the service bulletin described previously.
    Additionally, the proposed AD would remove Model 767 series 
airplanes from the applicability of the existing AD, since the subject 
unsafe condition on those airplanes is addressed in AD 95-08-11.

Cost Impact

    There are approximately 400 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 125 
airplanes of U.S. registry would be affected by this proposed AD.
    The actions that are currently required by AD 92-16-17 take 
approximately 12 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts cost approximately $510 
per airplane. Based on these figures, the cost impact on U.S. operators 
of the actions currently required is estimated to be $153,750, or 
$1,230 per airplane.
    The new actions that are proposed in this AD action would take 
approximately 2 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $6,400 per airplane. Based on these figures, the cost 
impact on U.S. operators of the proposed requirements of this AD is 
estimated to be $815,000, or $6,520 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.

Regulatory Impact

    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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-8327 (57 FR 
47987, October 21, 1992), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 95-NM-226-AD. Supersedes AD 92-16-17, Amendment 39-
8327.

    Applicability: Model 747-100, -200, and -300 series airplanes 
equipped with an off-wing, two-piece escape slide on Door 3; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (e) 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 escape slide to deploy, which could 
delay and possibly jeopardize the successful emergency evacuation of 
an airplane, accomplish the following:
    (a) Within 18 months after November 25, 1992 (the effective date 
of AD 92-16-17, amendment 39-8327), perform an inspection of the 
door opening thrusters of the escape system in accordance with OEA 
Service Bulletin 2174200-25-013, dated July 29, 1991. Repeat this 
inspection thereafter at intervals not to exceed 20 months until the 
replacement required by paragraph (c) of this AD is accomplished.
    (b) Within 18 months after November 25, 1992, inspect and modify 
the door latching mechanism of the escape slide compartment in 
accordance with Boeing Service Bulletin 747-25-2951, dated August 
15, 1991.
    (c) Within 2 years after the effective date of this AD, replace 
the door opening thrusters having part number (P/N) 60B50077-14 or -
17 with new thrusters having P/N 60B50077-19 in accordance with 
Boeing Service Bulletin 747-25-3073, dated September 21, 1995. 
Accomplishment of this replacement terminates the repetitive 
inspections required by this AD.
    (d) As of the effective date of this AD, no person shall install 
a door opening thruster having P/N 60B50077-14 or -17 on any 
airplane.
    (e) 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (f) 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.

    Issued in Renton, Washington, on June 19, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-16243 Filed 6-25-96; 8:45 am]
BILLING CODE 4910-13-U