[Federal Register Volume 66, Number 109 (Wednesday, June 6, 2001)]
[Proposed Rules]
[Pages 30343-30345]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-14145]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-143-AD]
RIN 2120-AA64


Airworthiness Directives; Gulfstream Aerospace Corporation Model 
G-159 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 all Gulfstream Aerospace 
Corporation Model G-159 airplanes. This proposal would require 
repetitive non-destructive testing inspections to detect corrosion of 
the skin of certain structural assemblies, and corrective action, if 
necessary. This

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proposal also would require x-ray and ultrasonic inspections to detect 
corrosion and cracking of the splicing of certain structural 
assemblies, and repair, if necessary. This action is necessary to 
detect and correct corrosion of the skin of certain structural 
assemblies, which could cause local instability failures of the wing 
under certain load conditions and result in degradation of wing 
capability. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by July 23, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 96-NM-143-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 96-NM-143-AD'' in the subject line and need not be 
submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Gulfstream Aerospace Corporation, P.O. Box 2206, M/S D-
10, Savannah, Georgia 31402-9980. This information may be examined at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Wichita Aircraft Certification Office, 1801 
Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.

FOR FURTHER INFORMATION CONTACT: Neil Berryman, Aerospace Engineer, 
Airframe and Propulsion Branch, ACE-117A, FAA, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 
450, Atlanta, Georgia 30337-2748; telephone (770) 703-6087; fax (770) 
703-6097.

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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-143-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. 96-NM-143-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The method of fabrication on Gulfstream Aerospace Corporation Model 
G-159 airplanes of spotwelding to join two layers of material precludes 
the use of any corrosion inhibitor on the faying surfaces. Therefore, 
corrosion can form by the entrance and entrapment of moisture or other 
corrosive agents between layers of the metal. The FAA has received 
reports that exfoliation corrosion has been found in the lower layer of 
the lower wing plank splices. This corrosion typically follows the 
grain boundaries into the ramp-up area. As a consequence of such 
corrosion, cracking may occur in the risers adjacent to the splices of 
the lower wing planks. This action is necessary to detect and correct 
corrosion of the skin of certain structural assemblies, which could 
cause local instability failures of the wing under certain load 
conditions and result in degradation of wing capability.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Gulfstream Customer Bulletin (CB) 
No. 337, dated December 10, 1993, which describes procedures for 
certain repetitive non-destructive testing (NDT) inspections to detect 
corrosion on certain areas (ailerons, elevators, rudder, flaps, 
horizontal stabilizer, vertical stabilizer, and aft fuselage skins, as 
well as lower wing plank splices). The CB also describes procedures for 
replacing components, if necessary. Accomplishment of the actions 
specified in the service bulletin is intended to adequately address the 
identified unsafe condition.
    Gulfstream has also issued Gulfstream Tool No. ST905-377, an x-ray 
negative that is a comparison chart, which describes specific levels of 
corrosion, and describes criteria for determining those levels of 
corrosion (``light,'' ``moderate,'' and ``severe'').

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 accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between the CB and the Proposed Rule

    Operators should note that the Gulfstream CB recommends that the 
compliance time for the initital NDT inspections should be 18 months 
from the release of the CB (December 10, 1993). However, this proposed 
AD would require the initial inspection within 9 months after the 
effective date of the AD. Operators also should note that, although the 
Gulfstream CB does not specify certain corrective actions for levels of 
corrosion, this proposed AD would require shortened repetitive 
intervals for the NDT inspections based on certain levels of corrosion, 
or replacement of the corroded component with a serviceable component.

Cost Impact

    There are approximately 144 Gulfstream Model G-159 airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 71 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 80 work hours per airplane to accomplish 
the

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proposed actions, and that the average labor rate is $60 per work hour. 
Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be $340,800, or $4,800 per airplane, per 
inspection cycle.
    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 proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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 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:

Gulfstream Aerospace Corporation: Docket 96-NM-143-AD.

    Applicability: All Model G-159 airplanes, 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 (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 corrosion of the skin of certain 
structural assemblies, which could cause local instability failures 
of the wing under certain load conditions and result in degradation 
of wing capability; accomplish the following:
    (a) Within 9 months after the effective date of this AD, perform 
a non-destructive test (NDT) to detect corrosion of the skins of the 
aileron rudder, rudder trim tab, flap, evaluator, fuselage, vertical 
stabilizer, and horizontal stabilizer; in accordance with Gulfstream 
Aerospace GI Customer Bulletin No. 337, dated December 10, 1993.
    (1) If no corrosion is detected, repeat the NDT inspections 
thereafter at intervals not to exceed 18 months.
    (2) If any corrosion is detected that meets the criteria of 
``light'' corrosion, as defined by Gulfstream Tool No. ST905-377, 
repeat the NDT inspections of that component thereafter at intervals 
not to exceed 12 months.
    (3) If any corrosion is detected that meets the criteria of 
``moderate'' corrosion, as defined by Gulfstream Tool No. ST905-377, 
repeat the NDT inspection of that component thereafter at intervals 
not to exceed 9 months.
    (4) If any corrosion is detected that meets the criteria of 
``severe'' corrosion, as defined by Gulfstream Tool No. ST905-377, 
prior to further flight, replace the component with a serviceable 
component, in accordance with the Gulfstream I Maintenance Manual.
    (b) Within 9 months after the effective date of this AD, perform 
a non-destructive test (NDT) to detect corrosion of the lower wing 
plank splices, in accordance with Gulfstream Aerospace GI Customer 
Bulletin No. 337, dated December 10, 1993.
    (1) If no corrosion is detected, repeat the NDT inspection at 
intervals not to exceed 18 months.
    (2) If any corrosion is detected, prior to further flight, 
repair in accordance with the customer bulletin.

Reporting Requirement

    (c) Within 10 days of performing the inspections required by 
paragraph (a) of this AD: Submit a report of inspection findings 
(both positive and negative) to Gulfstream Aerospace Corporation; 
Attention: Technical Operations--Mail Station D-10; P.O. Box 2206; 
Savannah, Georgia 31402-0080. 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.

Alternative Methods of Compliance

    (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, Wichita Aircraft Certification 
Office (ACO), FAA. Operators shall submit their requests through an 
appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Wichita ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Wichita ACO.

Special Flight Permits

    (e) 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 May 29, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-14145 Filed 6-5-01; 8:45 am]
BILLING CODE 4910-13-U