[Federal Register Volume 62, Number 5 (Wednesday, January 8, 1997)]
[Rules and Regulations]
[Pages 1038-1039]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-255]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-276-AD; Amendment 39-9876; AD 96-26-51]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747 Series Airplanes
Powered By Rolls Royce Model RB211 Series Engines
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) T96-26-51 that was sent
previously to all known U.S. owners and operators of certain Boeing
Model 747 series airplanes powered by Rolls Royce Model RB211 series
engines by individual telegrams. This AD requires a one-time inspection
to detect cracks and corrosion of various areas at all four engine
pylons, and repair of any cracked or corroded engine pylon. This action
is prompted by reports of cracking of the aft torque bulkhead at the
number 1 and number 2 engine pylons. The actions specified by this AD
are intended to detect and correct such cracking, which could result in
failure of the pylon and consequent separation of the engine from the
wing.
EFFECTIVE DATE: January 13, 1997, to all persons except those persons
to whom it was made immediately effective by telegraphic AD T96-26-51,
issued on December 13, 1996, which contained the requirements of this
amendment.
Comments for inclusion in the Rules Docket must be received on or
before March 10, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-276-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
Information concerning this AD may be obtained from or examined at
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Tamara Dow, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2771; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: On December 13, 1996, the FAA issued
telegraphic AD T96-26-51, which is applicable to certain Boeing Model
747 series airplanes powered by Rolls Royce Model RB211 series engines.
That action was prompted by two reports of cracking of the aft
torque bulkhead at the number 1 and number 2 engine pylons. This
cracking occurred on a Boeing Model 747-200F series airplane powered by
Rolls Royce Model RB211 series engines. The airplane had accumulated
69,506 total flight hours and 17,499 total flight cycles.
Investigation revealed that the aft torque bulkhead at the number 1
pylon was cracked completely through just above the lower spar fitting
where the fitting attaches to the diagonal brace. The crack extended
eight inches forward on the outboard side skin of the number 1 pylon.
In addition, the lower portion of the aft torque bulkhead at the number
1 pylon had separated and had dropped down approximately 0.5 inch.
Investigation also revealed that the aft torque bulkhead at the
number 2 pylon was cracked (1.2 inch) in approximately the same
location as the cracking on the number 1 pylon.
The cause of this cracking is unknown at this time. Modification of
the strut/wing, which is currently required by AD 95-13-05, amendment
39-9285 (60 FR 33333, June 28, 1995), had not yet been accomplished on
the airplane at the time of discovery of the cracking. However, it also
is not known if this modification would have prevented this condition.
Cracking of the aft torque bulkhead at the engine pylons, if not
detected and corrected in a timely manner, could result in failure of a
pylon and consequent separation of the engine from the wing.
FAA's Determination
The FAA has determined that a one-time inspection to detect cracks
and corrosion of the aft torque bulkhead at all four engine pylons is
necessary to address the identified unsafe condition in a timely
manner.
Explanation of Requirements of the Rule
Since the unsafe condition described is likely to exist or develop
on other airplanes of the same type design, the FAA issued telegraphic
AD T96-26-51 to require a one-time detailed visual inspection to detect
cracks and corrosion in the following areas: (1) The external surface
of the lower half of the aft torque bulkhead at all four engine pylons,
and (2) the external surface of the inboard and outboard side skins for
a distance of 36 inches forward of the plane of the aft torque bulkhead
at all four engine pylons. The AD also requires repair of any cracked
or corroded engine pylon. In addition, the AD requires that operators
submit a report of all inspection findings to the FAA.
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 December 13, 1996, to all known U.S. owners and operators of
certain Boeing Model 747 series airplanes powered by Rolls Royce Model
RB211 series engines. 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.
Interim Action
This is considered to be interim action. The reports of inspection
results that are required by this AD will enable the FAA to obtain
better insight into the nature, cause, and extent of cracking found at
the number 1 and number 2 engine pylons, and eventually to develop
final action to address the subject unsafe condition. Once final action
has been identified, the FAA may consider further rulemaking.
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
[[Page 1039]]
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 postcard on which the following statement is made: ``Comments
to Docket Number 96-NM-276-AD.'' The postcard will be date stamped and
returned to the commenter.
Regulatory Impact
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 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-26-51 Boeing: Amendment 39-9876. Docket 96-NM-276-AD.
Applicability: Model 747 series airplanes powered by Rolls Royce
Model RB211 series engines, certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise 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 (d) 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 and correct cracking of the aft torque bulkhead, which
could result in failure of a pylon and consequent separation of the
engine from the wing, accomplish the following:
(a) Prior to the accumulation of 12,000 total flight cycles, or
within 10 days after the effective date of this AD, whichever occurs
later, gain access to the aft torque bulkhead at each of the four
engine pylons through the aft fairing doors. Prior to further flight
after gaining access, accomplish paragraphs (a)(1) and (a)(2) of
this AD.
(1) Perform a one-time detailed visual inspection to detect
cracks and corrosion of the external surface of the lower half of
the aft torque bulkhead at all four engine pylons. Pay particular
attention to the area near the diagonal brace fitting.
(2) Perform a one-time detailed visual inspection to detect
cracks and corrosion of the external surface of the inboard and
outboard side skin for a distance of 36 inches forward of the plane
of the aft torque bulkhead at all four engine pylons.
(b) If any crack or corrosion is detected during any inspection
required by this AD, prior to further flight, repair the cracked/
corroded pylon in accordance with a method approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate.
(c) Within 10 days after accomplishing the inspections required
by paragraphs (a)(1) and (a)(2) of this AD, submit a report of any
findings to the Manager, Seattle ACO, FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056,
fax (206) 227-1181; and to the appropriate FAA Principal Maintenance
Inspector. The report shall include the items specified in
paragraphs (c)(1), (c)(2), and (c)(3) of this AD. Information
collection requirements contained in this regulation have been
approved by the Office of Management and Budget (OMB) under the
provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et
seq.) and have been assigned OMB control number 2120-0056.
(1) Airplane serial number;
(2) Total number of landings accumulated; and
(3) Location, size, and orientation of each crack.
(d) 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. 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.
(e) This amendment becomes effective on January 13, 1997, to all
persons except those persons to whom it was made immediately
effective by telegraphic AD T96-26-51, issued on December 13, 1996,
which contained the requirements of this amendment.
Issued in Renton, Washington, on December 31, 1996.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-255 Filed 1-7-97; 8:45 am]
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