[Federal Register Volume 59, Number 174 (Friday, September 9, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-20754]


[[Page Unknown]]

[Federal Register: September 9, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-03-AD; Amendment 39-9014; AD 94-18-01]

 

Airworthiness Directives; Boeing Model 757 and 767 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 757 and 767 series airplanes, that 
requires modification of the latch hook installation for the number two 
cockpit window frame. This amendment is prompted by reports of the 
flight crew executing rejected takeoffs (RTO) and air turnbacks (ATB) 
due to false ``closed'' indications for the number two cockpit window. 
The actions specified by this AD are intended to prevent unlatched (not 
completely closed) number two cockpit windows and the resultant 
execution of RTO's and ATB's by the flight crew.

DATES: Effective October 11, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 11, 1994.

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: Roy Boffo, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2780; 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 March 8, 1994 
(59 FR 10759). That action proposed to require modification of the 
latch hook installation for the number two cockpit window frame.
    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 proposal.
    Several commenters question the need for the rule and consider that 
the proposal should be withdrawn for various reasons:
    One of these commenters contends that the nature of the addressed 
problem does not constitute an unsafe condition. This commenter states 
that, if the window is not completely closed, it is not possible for 
the latch cams to engage with the latch posts; thus, improperly closed 
windows are readily identified by physically trying to open the window. 
The FAA does not concur. If the window latch cams do not engage with 
the latch posts, it is still possible to rotate the latch handle. 
Whenever the latch handle is rotated, a ``closed'' indicator appears 
above the window. This makes it possible for the window actually to be 
open, but to appear to be closed and to have a ``closed'' indicator as 
well. The modification required by this AD addresses that situation, 
since it will prevent the possibility of rotating the latch handle into 
the forward, latched position unless the window is fully closed. 
Because of the consequences associated with an open window, the FAA 
considers this modification to be warranted and appropriate.
    Some of these commenters consider that current flight crew 
procedures are adequate to address the problem that is the subject of 
the proposed AD. These commenters point out that current procedures 
provide for a check of these windows to ensure that they are closed and 
locked; some operators' procedures require that the flight crew check 
the windows twice. The FAA does not concur. As described above, the 
current configuration of the window latching mechanism and associated 
indicator make it possible for the window to appear to be closed and to 
have a ``closed'' indicator, even though the window is not actually 
closed and latched. Service experience has shown that the flight crew 
will not always verify that the window is closed if they have a 
``closed'' indication. For these reasons, the FAA finds that flight 
crew procedures alone are not effective in addressing the identified 
unsafe condition.
    Another of these commenters states that there has been only a 
limited number of operators that have experienced difficulty with the 
subject windows; this commenter does not consider that it is reasonable 
for the FAA to burden all operators with the requirements of the rule 
because of the service experience of only a few operators. The FAA 
acknowledges that only a few operators have experienced in service the 
problems addressed by this AD action. However, since the configuration 
of the windows, the window latching mechanism, and the associated 
indicating system is similar on all of the affected Model 757 and 767 
series airplanes, the FAA has determined that the potential exists for 
this problem to occur on any of these airplanes.
    Another of these commenters states that the referenced service 
bulletin describes the modification as desirable only to ``reduce noise 
in the cockpit'' should the subject windows not be latched. This 
commenter states that at no time have there been reports of an 
uncommanded window opening; instead, there have been reports only of 
false window latching, which resulted in air leakage and noise. 
Therefore, the commenter considers the proposed modification to be 
merely a ``product improvement'' and not necessarily meant to correct 
an unsafe condition. The FAA does not concur. The modifications 
described in the referenced service bulletins eliminate the possibility 
of the ``closed'' indicator being visible when the window is not 
actually fully closed. The air leakage and noise that have resulted 
from open windows have led to rejected takeoffs (RTO's) and air 
turnbacks (ATB's); some of the RTO's have resulted in considerable 
damage to the airplane. To address this unsafe condition, the FAA has 
determined that the need for the proposed modification is warranted. -
    Finally, one of these commenter states that there have been reports 
of RTO's and ATB's involving airplanes that have incorporated the 
modification; therefore, the modification will not eliminate these 
occurrences. The FAA acknowledges that RTO's and ATB's have taken place 
after modification, and points out that the subject modification is not 
intended to prevent all future occurrences of these incidents. 
Conversely, it is not intended that the modification terminate any 
requirements for crew preparation of the flight deck for flight. The 
modification does address a design problem that can lead the crew to 
believe that the window is closed when, in fact, it is not. -
    One commenter requests that the proposed rule be revised to provide 
``credit'' to operators with Model 767 series airplanes that have been 
previously modified only in accordance with Boeing Service Bulletin 
767-56-0002, dated August 30, 1985, and not in accordance with that 
service bulletin as amended by Notice of Status Change (NSC) 1, dated 
July 3, 1986, as specified in the notice. This commenter points out 
that NSC 1 simply added data concerning existing part accountability; 
additionally, NSC 1 contains a statement indicating that ``no more work 
is necessary on airplanes changed by the initial release of this 
service bulletin.'' The FAA concurs, and has revised the final rule 
accordingly. -
    This same commenter requests that the comment period be extended by 
an additional 60 days in order to obtain information as to whether or 
not all affected Model 767 series airplanes have already been modified 
in accordance with the proposed requirements of the rule. The commenter 
considers that, by obtaining such affirmative data, the Model 767 could 
be eliminated from the applicability of the rule. The FAA does not 
concur, and considers that such a delay in this rulemaking action is 
inappropriate. Regardless, as specified in the ``Compliance'' statement 
of the final rule, airplanes that have been modified previously in 
accordance with the requirements of the rule are considered in 
compliance and require no additional work relative to this rule. -
    One commenter requests that the proposed compliance time of 18 
months be extended to 30 months in order to accommodate parts delivery 
time and orderly modification of the fleet. This commenter states that 
the lead time necessary for obtaining the modification parts is 
extensive (44 weeks), and an 18-month compliance time is unreasonably 
short to expect operators of large fleets to modify all of the affected 
airplanes. The FAA concurs. In developing an appropriate compliance 
time for this AD action, the FAA intended that it fall during a time of 
regularly scheduled maintenance in order to allow the modification to 
be performed at a base where special equipment and trained maintenance 
personnel will be available if necessary. The FAA considers that 
extending the compliance time to 30 months will not adversely affect 
safety and will allow timely and orderly modification of the affected 
fleet. -
    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 640 Model 757 and 767 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 409 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 8 work hours per airplane to accomplish the required 
actions, and that the average labor rate is $55 per work hour. Required 
parts will cost approximately $2,000 per airplane. Based on these 
figures, the total cost impact of the AD on U.S. operators is estimated 
to be $997,960, or $2,440 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. However, the 
FAA has been advised that at least 44 of the affected airplanes have 
already been modified in accordance with the requirements of this AD, 
and that numerous others are either currently undergoing or will have 
undergone modification by the date that this AD is effective. 
Therefore, the future economic cost impact of this rule on U.S. 
operators is now only $890,600 (and, most likely, considerably less 
than that amount as of the effective date of this AD). -
    The FAA recognizes that the obligation to maintain aircraft in an 
airworthy condition is vital, but sometimes expensive. Because AD's 
require specific actions to address specific unsafe conditions, they 
appear to impose costs that would not otherwise be borne by operators. 
However, because of the general obligation of operators to maintain 
aircraft in an airworthy condition, this appearance is deceptive. 
Attributing those costs solely to the issuance of this AD is 
unrealistic because, in the interest of maintaining safe aircraft, most 
prudent operators would accomplish the required actions even if they 
were not required to do so by the AD. -
    A full cost-benefit analysis has not been accomplished for this AD. 
As a matter of law, in order to be airworthy, an aircraft must conform 
to its type design and be in a condition for safe operation. The type 
design is approved only after the FAA makes a determination that it 
complies with all applicable airworthiness requirements. In adopting 
and maintaining those requirements, the FAA has already made the 
determination that they establish a level of safety that is cost-
beneficial. When the FAA, as in this AD, makes a finding of an unsafe 
condition, this means that the original cost-beneficial level of safety 
is no longer being achieved and that the required actions are necessary 
to restore that level of safety. Because this level of safety has 
already been determined to be cost-beneficial, a full cost-benefit 
analysis for this AD would be redundant and unnecessary. -
    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

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

94-18-01  Boeing: Amendment 39-9014. Docket 94-NM-03-AD.

    Applicability: Model 757 series airplanes having line positions 
1 through 534 inclusive, and Model 767 series airplanes having line 
positions 1 through 114 inclusive; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent unlatched (not completely closed) number two cockpit 
windows and the resultant execution of rejected takeoffs and air 
turnbacks by the flight crew, accomplish the following:
    (a) Within 30 months after the effective date of this AD, modify 
the latch hook installation for the number two cockpit window frame 
in accordance with the applicable service bulletin indicated in 
either paragraph (a)(1) or (a)(2) of this AD.
    (1) For Model 757 series airplanes: Boeing Service Bulletin 757-
56-0007, dated May 6, 1993.
    (2) For Model 767 series airplanes: either Boeing Service 
Bulletin 767-56-0002, dated August 30, 1985; or Boeing Service 
Bulletin 767-56-0002 as amended by Notice of Status Change Number 
767-56-0002 NSC 1, dated July 3, 1986.
    (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: 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 modification shall be done in accordance with Boeing 
Service Bulletin 757-56-0007, dated May 6, 1993; or Boeing Service 
Bulletin 767-56-0002, dated August 30, 1985; or Boeing Service 
Bulletin 767-56-0002, as amended by Notice of Status Change Number 
767-56-0002 NSC 1, dated July 3, 1986; 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 11, 1994.

    Issued in Renton, Washington, on August 18, 1994.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-20754 Filed 9-8-94; 8:45 am]
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