[Federal Register Volume 59, Number 21 (Tuesday, February 1, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-584]
[[Page Unknown]]
[Federal Register: February 1, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-NM-138-AD; Amendment 39-8797; AD 94-01-15]
Airworthiness Directives; Boeing Model 747 Series Airplanes With
Stretched Upper Decks (SUD)
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 series airplanes, that requires
installation of an aluminum seal retainer on the bulb seal attached to
the fascia panels of the escape systems on the SUD. This amendment is
prompted by a report that, during deployment of an emergency evacuation
slide, the slide inflated but subsequently lost air from one chamber.
The actions specified by this AD are intended to prevent the bulb seal
from coming off the fascia panels and being ingested into the turbofans
of the escape systems on the stretched upper deck (SUD), which could
impede the inflation of the escape slide during an emergency situation.
DATES: Effective March 3, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of March 3, 1994.
ADDRESSES: The service information referenced in this AD may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124. 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: Jayson Claar, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2784; 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 Boeing Model 747 series airplanes with stretched upper
decks (SUD) was published in the Federal Register on September 21, 1993
(58 FR 48983). That action proposed to require installation of an
aluminum seal retainer on the bulb seal attached to the fascia panels
of the escape systems on the SUD.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Three commenters support the proposal.
One commenter considers that the proposed rule is not warranted
since there has been only one reported incident where the bulb seal was
ingested into the turbofan. The commenter states that, even during that
incident, the damage was limited to one of the escape slide's chambers
and the slide was still usable. The FAA does not concur with the
suggestion that this AD action is not warranted. While the commenter is
correct in noting that there has been only a single reported case of
ingestion of the bulb seal into the turbofans, the potential still
exists for a bulb seal to break away if there is no component to retain
it. The consequences of the bulb seal breaking away and being ingested
into the turbofan can ultimately impede the inflation of the escape
slide, which creates a potential unsafe condition by rendering the
slide unusable in the event of an emergency evacuation. Although the
commenter indicates that the incident slide was still usable after
being damaged, the FAA has determined that the potential exists for
similar or greater damage to occur on any of the subject escape slides,
as long as there is the possibility that the bulb seal can be ingested
into the turbofans. Installation of the bulb seal retainer, as required
by this AD, will positively address this potential unsafe condition by
preventing the separation of the bulb seal from the fascia panel.
This same commenter requests that one airplane be deleted from the
applicability of the AD. The airplane having line number 981 was
modified with the bulb seal retainer prior to delivery; therefore, the
unsafe condition does not exist with regard to this specific airplane.
The FAA concurs and has revised the applicability of the final rule
accordingly. Additionally, the economic impact information, below, has
been revised to indicate the deletion of this airplane from those
affected by the AD requirements.
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 290 Model 747 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 29
airplanes of U.S. registry will be affected by this AD, that it will
take approximately 4 work hours per airplane to accomplish the required
actions, and that the average labor rate is $55 per work hour. The cost
of required parts would be nominal. Based on these figures, the total
cost impact of the AD on U.S. operators is estimated to be $6,380, or
$220 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:
94-01-15 Boeing: Amendment 39-8797. Docket 93-NM-138-AD.
Applicability: Model 747 series airplanes with a stretched upper
deck, all line numbers up to and including line number 980;
certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent the bulb seal from coming off the fascia panels and
being ingested into the turbofans of the escape systems on the
stretched upper deck (SUD), which could impede the inflation of the
escape slide during an emergency situation, accomplish the
following:
(a) Within 6 months after the effective date of this AD, install
an aluminum seal retainer on the bulb seal attached to the fascia
panel of the escape systems on the SUD, in accordance with Boeing
Alert Service Bulletin 747-25A3056, dated July 12, 1993.
(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). 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 FAR
21.197 and 21.199 to operate the airplane to a location where the
requirements of this AD can be accomplished.
(d) The installation shall be done in accordance with Boeing
Alert Service Bulletin 747-25A3056, dated July 12, 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. Copies may be inspected at
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW.,
Renton, Washington; at the Office of the Federal Register, 800 North
Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment becomes effective on March 3, 1994.
Issued in Renton, Washington, on January 5, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-584 Filed 1-31-94; 8:45 am]
BILLING CODE 4910-13-U
