[Federal Register Volume 61, Number 90 (Wednesday, May 8, 1996)]
[Proposed Rules]
[Pages 20764-20766]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-11442]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-90-AD]
RIN 2120-AA64


Airworthiness Directives; Gulfstream Model G-1159 (G-II), G-1159A 
(G-III), and G-1159B (G-IIB) 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 all Gulfstream Model G-1159 (G-
II), G-1159A (G-III), and G-1159B (G-IIB) series airplanes. This 
proposal would require inspections to detect cracking and/or corrosion 
at various locations of the wings, and modification of cracked and/or 
corroded parts. This proposal is prompted by a report indicating that 
cracks, caused by stress corrosion, were found at various locations at 
buttock line (BL) 0 to BL 19 of the lower wing plank. The actions 
specified by the proposed AD are intended to prevent such stress 
corrosion cracking, which could result in structural failure of the 
wing under certain load conditions.

DATES: Comments must be received by June 17, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-90-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.
    The service information referenced in the proposed rule may be 
obtained from Gulfstream Aerospace Corporation, Technical Operations 
Department, P.O. Box 2206, M/S D-10, Savannah, Georgia 31402-2206. This 
information may be examined at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small 
Airplane Directorate, Atlanta Aircraft Certification Office, Campus 
Building, 1701 Columbia Avenue, Suite 2-160, College Park, Georgia.


[[Page 20765]]


FOR FURTHER INFORMATION CONTACT: Steve Flanagan, Aerospace Engineer, 
Airframe and Propulsion Branch, ACE-117A, FAA, Small Airplane 
Directorate, Atlanta Aircraft Certification Office, Campus Building, 
1701 Columbia Avenue, Suite 2-160, College Park, Georgia 30337-2748; 
telephone (404) 305-7363; fax (404) 305-7348.

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 96-NM-90-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-103, Attention: Rules 
Docket No. 96-NM-90-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received a report indicating that cracks were found on 
certain Gulfstream Model G-1159 (G-II), G-1159A (G-III), and G-1159B 
(G-IIB) series airplanes in the forward and aft flanges of the fail-
safe splice channels at the forward and aft splice locations at buttock 
line (BL) 0 to BL 19 of the lower wing planks. In the same location, 
cracks have also been found in the vicinity of the internal stiffener 
run-outs in the fail-safe tee angles of the wing plank, and in the 
connecting angles in the forward wing plank at BL 6. Investigation has 
revealed that this cracking is caused by stress corrosion. Stress 
corrosion cracking at BL 0 to BL 19 of the lower wing planks, if not 
detected and corrected in a timely manner, could result in structural 
failure of the wing under certain load conditions.

Explanation of Relevant Service Information

    The FAA has reviewed and approved the following Gulfstream customer 
bulletins, all of which are dated August 4, 1994:
    <bullet> Gulfstream II Customer Bulletin No. 412,
    <bullet> Gulfstream IIB Customer Bulletin No. 413, and
    <bullet> Gulfstream III Customer Bulletin No. 128.
    These customer bulletins describe procedures for radiographic 
inspections to detect cracking and/or corrosion of the lower wing plank 
at buttock line (BL) 0 to BL 19 and between the stack-ups at the BL 0 
to BL 6 ribs. These customer bulletins also describe procedures for 
non-destructive test (NDT) inspections to detect cracking and/or 
corrosion on the connecting angles from BL 6 to BL 19 ribs; the No. 1 
and No. 2 fail-safe tees 1 and 2 at the BL 6 to BL 19 ribs; the wing 
plank splice channels at the BL 6 to BL 19 ribs; and the butterfly 
splice plates.
    The FAA has also reviewed and approved the following Gulfstream 
service changes, all of which are dated February 15, 1996:
    <bullet> Gulfstream II Aircraft Service Change No. 490;
    <bullet> Gulfstream IIB Aircraft Service Change No. 491; and
    <bullet> Gulfstream III Aircraft Service Change No. 301.
    These aircraft service changes describe procedures for modification 
of cracked and/or corroded parts of the wings. This modification 
involves removal of all corrosion from the lower wing planks (forward, 
mid, and aft) and replacement or repair of the fail-safe channels (BL 
6-19) of the lower mid plank and tee clips (BL 6) of the lower forward 
plank.

Explanation of the Requirements of the 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 radiographic and NDT inspections to detect 
cracking and/or corrosion at various location of the wings, and 
modification of cracked and/or corroded parts of the wings. The actions 
would be required to be accomplished in accordance with the customer 
bulletins and aircraft service changes described previously.
    Corrosion and cracking at BL 0 to BL 19 in the lower wing planks is 
normally addressed by requiring repetitive inspections of the planks at 
18 month intervals that are based on calculations derived from the 
service history of the components involved; repetitive inspections of 
the lower wing planks will maintain the level of risk for undetected 
stress corrosion cracking at acceptable levels. The maintenance program 
for Model G-1159 (G-II), G-1159A (G-III), and G-1159B (G-IIB) series 
airplanes has been recently revised to extend the interval from 18 
months to 72 months for the removal of the fasteners at BL 0 to BL 19. 
The FAA has determined that the one-time inspection of the subject 
lower wing planks that would be required by this AD, coupled with the 
repetitive inspections that currently are a part of the maintenance 
program, is adequate to provide a level of reliability and safety 
equivalent to that required by the Federal Aviation Regulations (FAR). 
This combination of inspections will ensure that any corrosion and/or 
cracking is detected on the lower wing planks and modified before such 
conditions could affect the operational safety of the airplane.

Cost Impact

    There are approximately 445 Model G-1159 (G-II), G-1159A (G-III), 
and G-1159B (G-IIB) series airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 345 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
100 work hours per airplane to accomplish the 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 $2,070,000, or $6,000 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the requirements of this 
proposed AD action, and that no operator would accomplish those actions 
in the future if this AD were not adopted. However, the FAA has been 
advised that 304 U.S.-registered airplanes have been inspected in 
accordance with the requirements of this AD. Therefore, the future 
economic cost impact of this proposed AD on U.S. operators would be 
only $246,000.

[[Page 20766]]

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 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Gulfstream: Docket 96-NM-90-AD

    Applicability: All Model G-1159 (G-II), G-1159A (G-III), and G-
1159B (G-IIB) series 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 (c) 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 stress corrosion cracking at BL 0 to 19 of the lower 
wing planks, which could result in structural failure of the wing 
under certain load conditions, accomplish the following:
    (a) Within 9 months after the effective date of this AD, perform 
radiographic and non-destructive test (NDT) inspections to detect 
cracking and/or corrosion at various locations of the wings as 
specified in the Accomplishment Instructions of Gulfstream GIII 
Customer Bulletin No. 128, dated August 4, 1994; Gulfstream IIB 
Customer Bulletin No. 413, dated August 4, 1994; or Gulfstream II 
Customer Bulletin No. 412, dated August 4, 1994; as applicable.

    Note 2: Inspections accomplished prior to the effective date of 
this AD in accordance with the following applicable Gulfstream 
documents, are considered acceptable for compliance with paragraph 
(a) of this AD.
    <bullet> GII Maintenance Manual Interim Revision 48-3, dated 
April 27, 1992;
    <bullet> GII Maintenance Manual Interim Revision 15-3, dated 
April 27, 1992; or
    <bullet> GII Maintenance Manual Interim Revision 32-3, dated 
April 27, 1992
    (b) If any crack and/or corrosion is found during any inspection 
required by paragraph (a) of this AD, prior to further flight, 
modify the cracked and/or corroded parts of the wings as specified 
in the Modification Instructions of Gulfstream III Aircraft Service 
Change No. 301; Gulfstream IIB Aircraft Service Change No. 491; or 
Gulfstream II Aircraft Service Change No. 490; all dated February 
15, 1996; as applicable.

    Note 3: Modifications accomplished prior to the effective date 
of this AD in accordance with the following applicable Gulfstream 
documents, are considered acceptable for compliance with paragraph 
(b) of this AD.
    <bullet> Gulfstream III Aircraft Service Change No. 244 (not 
dated), as revised by Gulfstream III Aircraft Service Change No. 244 
AM 1, dated March 30, 1992;
    <bullet> Gulfstream IIB Aircraft Service Change No. 447, dated 
March 16, 1992, as revised by Gulfstream IIB Aircraft Service Change 
No. 447 AM 1, dated March 30, 1992; or
    <bullet> Gulfstream II Aircraft Service Change No. 439 (not 
dated), as revised by Gulfstream II Aircraft Service Change No. 439 
AM 1, dated March 30, 1992
    (c) 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, Atlanta Aircraft Certification 
Office (ACO), FAA, Small 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, Atlanta ACO.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Atlanta ACO.
    (d) 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 2, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-11442 Filed 5-7-96; 8:45 am]
BILLING CODE 4910-13-U