AD Amdt-39-9335

[Federal Register Volume 60, Number 154 (Thursday, August 10, 1995)]
[Rules and Regulations]
[Pages 40748-40750]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 95-19653]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-130-AD; Amendment 39-9335; AD 95-15-52]


Airworthiness Directives; Boeing Model 747-100 and -200 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) T95-15-52 that was sent 
previously to all known U.S. owners and operators of certain Boeing 
Model 747-100 and -200 series airplanes by individual telegrams. This 
AD requires a revision of the Airplane Flight Manual (AFM) and Airplane 
Weight and Balance Supplement to restrict cargo loading to a certain 
level. This AD also provides for the removal of the restrictions 
following accomplishment of a modification of the longitudinal floor 
beams. This amendment is prompted by a determination that inadequate 
strength in the floor beams exists on certain airplanes that have been 
modified for cargo configurations. The actions specified by this AD are 
intended to prevent failure of the longitudinal floor beams, which may 
cause the keel beam to fail and result in rupture of the fuselage.

DATES: Effective August 25, 1995, to all persons except those persons 
to whom it was made immediately effective by telegraphic AD T95-15-52, 
issued July 14, 1995, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before October 10, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 

[[Page 40749]]
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-130-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    Information pertaining to this AD may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Steven C. Fox, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2777; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: On July 14, 1995, the FAA issued telegraphic 
AD T95-15-52, which is applicable to Model 747-100 series airplanes 
modified in accordance with Supplemental Type Certificate (STC) 
SA2322SO, SA2323SO, or SA5199NM; and Model 747-200 series airplanes 
modified in accordance with STC SA4227NM-D or SA5759NM.
    Certain Model 747-100 and -200 series airplanes have been converted 
from a passenger configuration to a freighter configuration in 
accordance with STC's SA2322SO and SA2323SO (for Model 747-100 series 
airplanes) and SA4227NM-D (for Model 747-200 series airplanes). These 
STC's include, as part of their data packages, new Weight and Balance 
Supplements that specify the maximum allowable linear load per inch 
(commonly referred to as ``running load'') along the length of the 
fuselage. The Supplements increased this limit from 66.7 pounds per 
inch to 240 pounds per inch between Body Stations (BS) 1000 and 1480. 
The Supplements also define the maximum area load (expressed in pounds 
per square foot). The Supplement increased this limit from 100 pounds 
per square foot to 320 pounds per square foot between BS 1000 and BS 
1480.
    On January 16, 1990, the FAA issued AD 90-06-06, amendment 39-6490 
(55 FR 8374, March 7, 1990), applicable to certain Boeing Model 747 
series airplanes, to require structural modifications of older 
airplanes, including a requirement to modify the longitudinal floor 
beams. Recently, an operator of Model 747 airplanes applied for 
approval of an alternative method of compliance (AMOC) to AD 90-06-06. 
In reviewing the data to approve this AMOC, the FAA has found that the 
longitudinal floor beams between BS 1265 and BS 1480 had not been 
upgraded to withstand the increased running loads that would result 
from an airplane's conversion to freighter service. These Body Stations 
comprise a 215 inch-long linear portion of the fuselage over the wheel 
well section of the airplane.
    Furthermore, the FAA finds that this same problem of inadequate 
strength in the floor beams exists on Model 747-100 and -200 series 
airplanes for which the type design has been changed to allow operation 
in accordance with STC's SA5199NM (for Model 747-100 series airplanes) 
and SA5759NM (for Model 747-200 series airplanes). These two STC's 
modify the weight and balance limitations of STC's SA2322SO, SA2323SO, 
and SA4227NM-D. However, these two STC's continue to define the maximum 
running load at 240 pounds per inch and the maximum area load at 320 
pounds per square foot without strengthening the floor beam structure 
between BS 1000 and BS 1480.
    The FAA has determined that a running load of 240 pounds per inch, 
for the freighter configuration, is above the capability of floor beam 
structure between BS 1265 and BS 1480. Additionally, the FAA finds that 
this structure, when loaded to the STC's-allowed limits is not 
sufficiently strong to sustain limit loads under all of the airspeed 
and load factor conditions, including those defined by section 25.333, 
``Flight envelope,'' and section 25.341, ``Gust loads,'' of the Federal 
Aviation Regulations (14 CFR 25.333 and 14 CFR 25.341). Failure of the 
longitudinal floor beams may cause the keel beam to fail, and result in 
the rupture of the fuselage.
    Since the unsafe condition described is likely to exist or develop 
on other airplanes having these STC's as part of their type design, the 
FAA issued Telegraphic AD T95-15-52 to require a revision to the 
Limitations section of the FAA-approved Airplane Flight Manual (AFM) 
and the Limitations section of the Airplane Weight and Balance 
Supplement to restrict cargo loading to a suitable level. The level 
established by this AD is based upon an FAA evaluation of the 
unmodified floor beam structure. The AD also provides for the removal 
of the restrictions following accomplishment of a modification of the 
longitudinal floor beams in accordance with a method approved by the 
FAA.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A Note has 
been included in this rule to clarify this long-standing requirement.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual telegrams 
issued on July 14, 1995 to all known U.S. owners and operators of the 
affected Boeing Model 747-100 and -200 series airplanes. These 
conditions still exist, and the AD is hereby published in the Federal 
Register as an amendment to section 39.13 of the Federal Aviation 
Regulations (14 CFR 39.13) to make it effective to all persons.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped 

[[Page 40750]]
postcard on which the following statement is made: ``Comments to Docket 
Number 95-NM-130-AD.'' The postcard will be date stamped and returned 
to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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, 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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

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

95-15-52  Boeing: Amendment 39-9335. Docket 95-NM-130-AD.

    Applicability: Model 747-100 series airplanes modified in 
accordance with Supplemental Type Certificates (STC) SA2322SO, 
SA2323SO, or SA5199NM; and Model 747-200 series airplanes modified 
in accordance with STC's SA4227NM-D or SA5759NM; 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 use the authority 
provided in paragraph (c) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent structural failure of the longitudinal floor beams 
and keel beam and the subsequent rupture of the fuselage, accomplish 
the following:
    (a) Within 24 clock hours (not flight hours) after the effective 
date of this AD, revise the Limitations section of the FAA-approved 
Airplane Flight Manual (AFM) and the Limitations section of the 
Airplane Weight and Balance Supplement (Model 747-100 or -200 series 
airplanes) to include the following information. This may be 
accomplished by inserting a copy of this AD in the AFM.
    ``1.1  MAIN CARGO DECK LIMITS (ADDITION):
    Each of the following payload limits for pallet cargo apply to 
the main cargo deck floor between Body Stations 1265 and 1480.

    Note: These limits take precedence over any other payload limits 
that may appear elsewhere in this or in any other document.

    1. Do not exceed a linear load of 96.0 pounds per inch between 
Body Stations 1265 and 1480.
    2. The maximum local floor loading in any area located between 
Body Stations 1265 and 1480 shall not exceed 150 pounds per square 
foot.
    3. The cargo pallets that are located entirely or partially 
between Body Stations 1265 and 1480 are restricted as follows:
    A. Pallets that are 96.0 inches in width and 125.0 inches in 
length shall not exceed a 1.0 g loading of 6,000 pounds.
    B. Pallets that are 88.0 inches in width and 125.0 inches in 
length shall not exceed a 1.0 g loading of 5,500 pounds.
    C. Pallets that are 88.0 inches in width and 108.0 inches in 
length shall not exceed a 1.0 g loading of 4,800 pounds.'' -
    (b) Accomplishment of a modification of the longitudinal floor 
beams in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate, constitutes terminating action for the limitation 
requirements of paragraph (a) of this AD. The AFM limitation and 
Weight and Balance Supplement limitation may be removed following 
accomplishment of such a modification. -
    (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 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.

     -(d) This amendment becomes effective on August 25, 1995, to 
all persons except those persons to whom it was made immediately 
effective by telegraphic AD T95-15-52, issued on July 14, 1995, 
which contained the requirements of this amendment.

    Issued in Renton, Washington, on August 3, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-19653 Filed 8-9-95; 8:45 am]
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