[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