[Federal Register Volume 59, Number 29 (Friday, February 11, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2182]


[[Page Unknown]]

[Federal Register: February 11, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-128-AD; Amendment 39-8812; AD 94-03-05]

 

Airworthiness Directives; Boeing Model 747-200B, -200C, -300, -
400, and -400D Series Airplanes Equipped With Passenger Oxygen System 
Reservoir Mask Assemblies, Boeing Part Numbers 10-60137-152 through -
165

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 747-200B, -200C, -300, -400, and 
400D series airplanes, that requires a revision to the FAA-approved 
maintenance program to require unrestricted opening of the passenger 
service unit (PSU) door during functional testing of the passenger 
oxygen system; and requires an inspection to detect leaks in certain 
passenger oxygen system reservoir bags, and marking and replacement of 
damaged mask assemblies. This amendment is prompted by reports that the 
passenger oxygen mask reservoir bags became overpressurized and split 
at the seams, resulting in failure of the bags. The actions specified 
by this AD are intended to ensure the delivery of emergency oxygen 
through the passenger oxygen system reservoir mask assemblies.

DATES: Effective March 14, 1994.

    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 14, 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: 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 to include an airworthiness directive (AD) that is 
applicable to certain Boeing Model 747-200B, -200C, -300, -400, and -
400D series airplanes was published in the Federal Register on August 
23, 1993 (58 FR 44468). That action proposed to revise the FAA-approved 
maintenance program to require unrestricted opening of the passenger 
service unit (PSU) door during functional testing of the passenger 
oxygen system; and to require an inspection to detect leaks in certain 
passenger oxygen system reservoir bags, and marking and replacement of 
damaged mask assemblies.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received. -
    Two commenters support the proposed rule.
    One commenter notes that an unsafe condition does not exist since 
its airplanes are equipped with approximately 20 percent more oxygen 
masks than the maximum number of passengers, and the projected failure 
rate for these masks is estimated to be only 10 to 15 percent. From 
this comment, the FAA infers that the commenter is requesting that the 
rule be withdrawn. The FAA does not concur. Although the projected 
failure rate is lower than the number of available masks, the FAA has 
determined that passengers using defective masks may not realize that 
the masks are supplying an insufficient quantity of oxygen; and thus, 
passengers would not seek out spare oxygen masks. Therefore, the 
potential would still exist for passengers to be unable to obtain 
unrestricted delivery of emergency oxygen through the passenger oxygen 
system reservoir mask assembly. This AD action addresses that potential 
unsafe condition.
    Boeing Commercial Airplane Group requests that the applicability of 
the proposal be revised to exclude airplanes that were delivered prior 
to August 1991. Boeing indicates that data have demonstrated that the 
masks installed on those airplanes have had significantly fewer leaks/
failures than masks installed on airplanes that were delivered after 
August 1991; therefore, those earlier airplanes would not necessarily 
be subject to the same unsafe condition addressed by the proposed AD 
action. The FAA does not concur with the commenter's request to exclude 
certain airplanes from the applicability. The FAA has reviewed the new 
data concerning the failure rate of the subject masks, which indicate 
that the masks' failure rate is lower than previously anticipated. 
While the data do demonstrate that airplanes delivered prior to August 
1991 have had significantly fewer leaking masks that fail to provide 
oxygen at or above FAA-required levels than those airplanes delivered 
in August 1991 and later, the FAA does not consider that this lower 
failure rate warrants the exclusion of any airplanes from the 
requirements of the rule. However, in light of the lower than 
originally anticipated failure rates for all of these masks, coupled 
with the unlikely event of decompression of the airplane, the FAA has 
reconsidered the proposed compliance time for inspection and 
replacement of the masks, and has determined that the compliance time 
can be extended for all airplanes without adversely affecting safety. 
Accordingly, the final rule has been revised to require a 15-month 
compliance time for Model 747-200B, -200C, and -300 series airplanes 
(the earlier-delivered airplanes), and a 180-day compliance time for 
Model 747-400 and -400D series airplanes.
    Several other commenters request that the proposed compliance time 
of 45 days to inspect and replace the masks be extended for a variety 
of reasons: Two of these commenters request that the proposed 
compliance time be revised to coincide with operators' regularly 
scheduled maintenance periods. One of these commenters suggests an 
alternative compliance time of ``the next 3C check'' for Model 747-200 
series airplanes, and ``the next 2C check'' for Model 747-400 series 
airplanes. One of these commenters did not offer an alternative 
suggestion to the proposed compliance time; however, the commenter 
asserts that the supplier of these replacement oxygen masks cannot 
deliver an adequate quantity of original or modified oxygen masks 
within the proposed compliance time, therefore an extension is 
necessary. Another commenter requests that the proposed compliance time 
be revised to coincide with the time at which a newly-designed mask is 
anticipated to become available. As discussed above, the FAA has 
extended the compliance time for the required actions, although not for 
the reasons requested by these commenters. The extended compliance 
time, however, should be sufficient to allow the inspection and 
replacement actions to be accomplished during normally scheduled 
maintenance, and to allow for any anticipated new mask design to become 
available.
    Several commenters request that the proposal be revised to include 
an option to replace the currently installed passenger oxygen masks 
with improved oxygen masks. These commenters request that installation 
of these improved oxygen masks eliminate the need to perform a one-time 
visual inspection to detect leaks in the passenger oxygen system 
reservoir bags. The FAA does not concur. The FAA acknowledges that 
Boeing is currently developing new passenger oxygen masks; however, 
those masks are not yet available. The FAA considers that delaying this 
action until the masks are available would be inappropriate. Since an 
unsafe condition exists, the FAA finds that defective masks must be 
replaced to ensure continued safety. Therefore, when the improved masks 
are developed, approved, and available, affected operators may request 
approval to install these improved masks as an alternative method of 
compliance, under the provisions of paragraph (e) of the final rule. -
    Two commenters note that the cost estimate presented in the 
preamble to the Notice was too low and did not take into account the 
time to clean, sanitize, repack, and stow the passenger oxygen masks 
following the proposed inspection. The commenters state that the 
required inspection, and the consequent cleaning, sanitizing, 
repacking, and stowing of the oxygen masks would necessitate 
approximately 90 work hours. After considering the data presented by 
commenters, the FAA concurs that the number of work hours required to 
accomplish the required actions is higher than previously approximated; 
the economic impact information, below, has been revised to indicate 
this higher amount. The economic analysis, however, is limited only to 
the cost of actions actually required by the rule. It does not consider 
the costs of ``on condition'' actions, e.g., ``repair, if necessary,'' 
since those actions would be required to be accomplished, regardless of 
AD direction, in order to correct an unsafe condition identified in an 
airplane and to ensure operation of that airplane in an airworthy 
condition, as required by the Federal Aviation Regulations.
    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 160 Boeing Model 747-200B, -200C, -300, -
400, and -400D series airplanes of the affected design in the worldwide 
fleet. The FAA estimates that 25 airplanes of U.S. registry will be 
affected by this AD, that it will take approximately 90 work hours per 
airplane to accomplish the required actions, and that the average labor 
rate is $55 per work hour. Based on these figures, the total cost 
impact of the AD on U.S. operators is estimated to be $123,750, or 
$4,950 per airplane. This total cost figure assumes that no operator 
has yet accomplished the requirements of this AD.
    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 14 CFR part 
39 of the Federal Aviation Regulations 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:


94-03-05 Boeing: Amendment 39-8812. Docket 93-NM-128-AD.
    Applicability: Model 747-200B, -200C, -300, -400, and -400D 
series airplanes equipped with passenger oxygen system reservoir 
mask assemblies, having Boeing part numbers 10-60137-152 through -
165 inclusive; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure the delivery of emergency oxygen through the passenger 
oxygen system reservoir mask assemblies, accomplish the following:
    (a) For all airplanes: Within 45 days after the effective date 
of this AD, revise the FAA-approved maintenance program to require 
unrestricted opening of the passenger service unit (PSU) door during 
functional testing of the passenger oxygen system.
    (b) After accomplishing the requirements of paragraph (a) of 
this AD, perform a one-time visual inspection to detect leaks in the 
passenger oxygen system reservoir bags, in accordance with Boeing 
Telex M-7240-93-1411, dated July 20, 1993, at the time specified in 
either paragraph (b)(1) or (b)(2) of this AD, as applicable.
    (1) For Model 747-200B, -200C, and -300 series airplanes listed 
in Boeing Telex M-7240-93-1411, dated July 20, 1993: Within 15 
months after the effective date of this AD.
    (2) For Model 747-400 and 747-400D series airplanes listed in 
Boeing Telex M-7240-93-1411, dated July 20, 1993: Within 180 days 
after the effective date of this AD.
    (c) If the masks inflate properly during the inspection required 
by paragraph (b) of this AD: No further action is required by this 
AD.
    (d) If any mask does not inflate properly during the inspection 
required by paragraph (b) of this AD: Prior to further flight, mark 
the mask assembly and replace it with a new or serviceable mask 
assembly, in accordance with Boeing Telex M-7240-93-1411, dated July 
20, 1993.
    (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: 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 FAR 
21.197 and 21.199 to operate the airplane to a location where the 
requirements of this AD can be accomplished.
    (g) The inspection, marking, and replacement shall be done in 
accordance with Boeing Telex M-7240-93-1411, dated July 20, 1993. 
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.
    (h) This amendment becomes effective on March 14, 1994.

    Issued in Renton, Washington, on January 26, 1994.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-2182 Filed 2-10-94; 8:45 am]
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