[Federal Register Volume 64, Number 161 (Friday, August 20, 1999)]
[Proposed Rules]
[Pages 45470-45472]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21691]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-02-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 Series Airplanes

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 737 series 
airplanes. This proposal would require a one-time detailed visual 
inspection of the upper decompression panel on the flight deck door to 
verify that a minimum overlap dimension exists, and corrective action, 
if necessary. This proposal is prompted by reports indicating that, 
during production, some upper decompression panels were installed 
incorrectly on the flight deck door. The actions specified by the 
proposed AD are intended to detect an incorrectly installed upper 
decompression panel, which could cause the emergency exit panel on the 
flight deck door to become inoperable, thereby preventing crewmembers 
from performing essential duties during an emergency evacuation.

DATES: Comments must be received by October 4, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-02-AD, 1601 Lind Avenue, SW., 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.

[[Page 45471]]

    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: Mike Thompson, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-1157; fax (425) 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 99-NM-02-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-114, Attention: Rules 
Docket No. 99-NM-02-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    During a pre-delivery interior compliance inspection, the FAA 
discovered that the emergency exit panel installed on the flight deck 
door of a Boeing Model 737 series airplane did not open properly. The 
emergency exit panel contains an upper decompression panel that allows 
pressure to equalize in the event of a rapid decompression. This panel 
also serves as an alternate escape path from the crew cabin if the 
flight deck door is damaged during an emergency landing. Subsequent 
investigation revealed that if the upper decompression panel is 
installed incorrectly, an interference between this panel and a 
decorative channel could cause the emergency exit panel to bind. Such 
binding could cause the panel to become inoperable as an emergency 
exit; however, the panel would still function properly in the event of 
a rapid decompression. The FAA found this problem on two airplanes 
prior to delivery, and has determined that it could also exist on 
certain Model 737-300/-400/-500 series airplanes, as well as on certain 
Model 737-600/-700/-800 series airplanes, that have already been 
delivered. The actions specified by the proposed AD are intended to 
detect an incorrectly installed upper decompression panel, which could 
cause the emergency exit panel on the flight deck door to become 
inoperable, thereby preventing crewmembers from performing essential 
duties during an emergency evacuation.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 737-52-
1128, dated April 22, 1999, which describes procedures to inspect the 
upper decompression panel on the flight deck door of certain Model 737-
300/-400/-500 series airplanes to verify that a minimum overlap 
dimension of 0.05 inch exists. If the minimum overlap does not exist, 
the service bulletin provides instructions to adjust the upper 
decompression panel and, if necessary, an adjacent decorative channel, 
to establish the correct overlap dimension.
    The FAA has also reviewed and approved Boeing Service Bulletin 737-
52-1137, dated May 13, 1999, which describes procedures to inspect the 
upper decompression panel on the flight deck door of certain Model 737-
600/-700/-800 series airplanes to verify that a minimum overlap 
dimension of 0.05 inch exists. If the minimum overlap does not exist, 
the service bulletin provides instructions to adjust the upper 
decompression panel and, if necessary, an adjacent decorative channel, 
to establish the correct overlap dimension.
    Accomplishment of the actions specified in the two service 
bulletins discussed above, as applicable, is intended to adequately 
address the identified unsafe condition.

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 require accomplishment of the actions specified in 
the service bulletins described previously, except as discussed below.

Differences Between Proposed Rule and the Service Bulletins

    Operators should note that, although the service bulletins 
recommend that the inspection be performed at the next convenient 
maintenance opportunity, the FAA has determined that an unspecified 
maintenance interval would not address the unsafe condition in a timely 
manner. In developing an appropriate compliance time for this AD, the 
FAA considered not only the manufacturer's recommendation, but the 
degree of urgency associated with addressing the unsafe condition, the 
average utilization of the affected fleet, and the time necessary to 
perform the inspection (1 hour). In light of all of these factors, the 
FAA finds an 18-month compliance time for completing the required 
actions to be warranted, in that it represents an appropriate interval 
of time allowable for affected airplanes to continue to operate without 
compromising safety.
    Operators also should note that, although the service bulletins 
specify accomplishment of an inspection of the upper decompression 
panel on the flight deck door to verify that a minimum overlap 
dimension of 0.05 inch exists, this proposed AD refers to that 
inspection as a detailed visual inspection. The FAA finds that 
``detailed visual inspection'' is the appropriate terminology for the 
inspection described in the service bulletins. Additionally, a 
definition of a detailed visual inspection is included in Note 2 of 
this proposed AD.

Cost Impact

    There are approximately 1299 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 901 airplanes of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 1 work hour per airplane to accomplish the proposed 
inspection, and that the average labor rate is $60 per work hour. Based 
on these figures, the cost impact of the inspection proposed by this AD 
on U.S. operators is estimated to be $54,060, or $60 per airplane.

[[Page 45472]]

    The 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.

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 adding the following new 
airworthiness directive:

Boeing: Docket 99-NM-02-AD.

    Applicability: Model 737 series airplanes, as listed in Boeing 
Service Bulletin 737-52-1128, dated April 22, 1999, or in Boeing 
Service Bulletin 737-52-1137, dated May 13, 1999; 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 request approval for an 
alternative method of compliance in accordance with paragraph (c) 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 detect an incorrectly installed upper decompression panel, 
which could cause the emergency exit panel on the flight deck door 
to become inoperable, thereby preventing crewmembers from performing 
essential duties during an emergency evacuation, accomplish the 
following:

One-Time Inspection

    (a) Within 18 months after the effective date of this AD, 
perform a one-time detailed visual inspection of the upper 
decompression panel on the flight deck door to verify that a minimum 
overlap dimension of 0.05 inch exists, as specified in Boeing 
Service Bulletin 737-52-1128, dated April 22, 1999 (for Model 737-
300/-400/-500 series airplanes); or Boeing Service Bulletin 737-52-
1137, dated May 13, 1999 (for Model 737-600/-700/-800 series 
airplanes); as applicable.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

Corrective Action

    (b) If a minimum overlap dimension of 0.05 inch is not found 
during the inspection required by paragraph (a) of this AD, prior to 
further flight, adjust the decompression panel and, as applicable, 
the adjacent decorative channel, in accordance with Boeing Service 
Bulletin 737-52-1128, dated April 22, 1999 (for Model 737-300/-400/-
500 series airplanes); or Boeing Service Bulletin 737-52-1137, dated 
May 13, 1999 (for Model 737-600/-700/-800 series airplanes); as 
applicable.

Alternative Methods of Compliance

    (c) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (d) 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 August 16, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-21691 Filed 8-19-99; 8:45 am]
BILLING CODE 4910-13-U