[Federal Register Volume 64, Number 248 (Tuesday, December 28, 1999)]
[Proposed Rules]
[Pages 72582-72584]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-33570]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-206-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Boeing Model 747 series
airplanes. This proposal would require a one-time inspection to
determine whether H-11 steel bolts are installed as attach and support
bolts at the trailing edge flap transmissions, and replacement of any
H-11 steel bolt with an Inconel bolt. This proposal is prompted by
reports of fracture or cracking of H-11 steel bolts at the flap
transmissions. The actions specified by the proposed AD are intended to
prevent loss of a flap transmission, which could reduce lateral
controllability of the airplane.
DATES: Comments must be received by February 11, 2000.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-206-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9 a.m. and 3 p.m., Monday through Friday, except
Federal holidays.
The service information referenced in the proposed rule may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Barbara Mudrovich, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Transport
[[Page 72583]]
Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind
Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2983;
fax (425) 227-1181.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed 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 above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 99-NM-206-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules
Docket No. 99-NM-206-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports indicating that H-11 steel bolts on
trailing edge flap transmissions installed on certain Boeing Model 747
series airplanes have fractured or cracked due to stress corrosion.
Bolts made of H-11 steel are known to be susceptible to such stress
corrosion cracking. The presence of moisture leads to stress corrosion
and, combined with other factors such as preload and shank corrosion,
can result in fractured or cracked bolts. Broken bolts could lead to
loss of a flap transmission, which could result in flap asymmetry, flap
skew, or collateral system damage. This condition, if not corrected,
could result in reduced lateral controllability of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Alert Service Bulletin
747-27A2376, dated July 1, 1999, which describes procedures for a one-
time general visual inspection to determine whether H-11 steel bolts
are installed as attach and support bolts at the trailing edge flap
transmissions. If an H-11 steel bolt is installed, the alert service
bulletin describes procedures for replacement with an Inconel bolt.
Accomplishment of the replacement specified in the alert service
bulletin is intended to adequately address the identified unsafe
condition.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would require a one-time general visual inspection to
determine whether H-11 steel bolts are installed as attach and support
bolts at the trailing edge flap transmissions, and replacement of any
H-11 steel bolt with an Inconel bolt. The actions would be required to
be accomplished in accordance with the alert service bulletin described
previously, except as discussed below.
Differences Between Proposed Rule and Alert Service Bulletin
Operators should note that, if any H-11 steel bolt is detected
during the inspection specified in this proposed AD, the proposed AD
would require replacement of any H-11 steel bolt with an Inconel bolt
prior to further flight. The alert service bulletin describes an option
to defer replacement of an H-11 steel bolt by performing a torque
inspection to determine whether the H-11 steel bolt is broken. If an H-
11 steel bolt is not broken, the alert service bulletin allows
replacement of the H-11 steel bolt to be deferred for up to 18 months
after accomplishment of the inspection. The FAA has determined that
such a compliance time would not address the identified unsafe
condition in a timely manner. In developing an appropriate compliance
time for this AD, the FAA considered not only the manufacturer's
recommendation, but the degree of urgency associated with addressing
the subject unsafe condition, and the time necessary to perform the
replacement (approximately four hours per affected flap transmission).
In light of these factors, the FAA finds a requirement to replace any
H-11 steel bolt with an Inconel bolt prior to further flight to be
warranted, in order to ensure the continued safety of the transport
airplane fleet.
Cost Impact
There are approximately 775 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 226 airplanes of U.S. registry
would be affected by this proposed AD, and that it would take
approximately 6 work hours per airplane to accomplish the proposed
inspection, at an average labor rate of $60 per work hour. Based on
these figures, the cost impact of the inspection proposed by this AD on
U.S. operators is estimated to be $81,360, or $360 per airplane.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the proposed requirements of
this AD action, and that no operator would accomplish those actions in
the future if this AD were not adopted.
Regulatory Impact
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, 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 copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting 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.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
part
[[Page 72584]]
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:
Boeing: Docket 99-NM-206-AD.
Applicability: Model 747-100, -100B, -100B SUD, -200B, -200C, -
200F, -300, -400, -400D, -400F, and 747SR series airplanes; line
positions 1 through 871 inclusive; 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 request approval for an
alternative method of compliance in accordance with paragraph (b) 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 prevent loss of a flap transmission, which could reduce
lateral controllability of the airplane, accomplish the following:
Replacement
(a) Within 1 year after the effective date of this AD, perform a
one-time general visual inspection to determine whether H-11 steel
bolts are installed as attach and support bolts at the trailing edge
flap transmissions, in accordance with Boeing Alert Service Bulletin
747-27A2376, dated July 1, 1999.
(1) If no H-11 steel bolt is found, no further action is
required by this AD.
(2) If any H-11 steel bolt is found, prior to further flight,
replace with an Inconel bolt, in accordance with the alert service
bulletin.
Note 2: For the purposes of this AD, a general visual inspection
is defined as: ``A visual examination of an interior or exterior
area, installation, or assembly to detect obvious damage, failure,
or irregularity. This level of inspection is made under normally
available lighting conditions such as daylight, hangar lighting,
flashlight, or drop-light, and may require removal or opening of
access panels or doors. Stands, ladders, or platforms may be
required to gain proximity to the area being checked.''
Alternative Methods of Compliance
(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), 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
Special Flight Permits
(c) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
Issued in Renton, Washington, on December 21, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-33570 Filed 12-27-99; 8:45 am]
BILLING CODE 4910-13-U
