[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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