[Federal Register Volume 62, Number 44 (Thursday, March 6, 1997)]
[Proposed Rules]
[Pages 10226-10228]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5462]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 97-NM-19-AD]
RIN 2120-AA64


Airworthiness Directives; Gulfstream Aerospace Corporation Model 
G-159 (G-I) Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Gulfstream Model G-
159 (G-I) airplanes, that currently requires repetitive inspections to 
detect chafe wear on the upper diagonal engine mount tube, and 
replacement or repair, if necessary. This action would require the 
installation of chafe guards at the engine mounts, which would 
terminate the currently required inspections. It also would require 
that the chafe guards then be repetitively inspected for chafe wear. 
This proposal is prompted by the development of a modification that 
will provide better protection of the subject area against future chafe 
wear. The actions specified by the proposed AD are intended to prevent 
excessive chafe wear in the area of the upper diagonal engine mount 
tubes and trusses; if not detected and corrected, such wear could 
result in failure of the engine mount assembly and possible separation 
of the engine from the airplane.

DATES: Comments must be received by April 14, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-19-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.

FOR FURTHER INFORMATION CONTACT: Christina Marsh, 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) 305-7362; 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

[[Page 10227]]

postcard on which the following statement is made: ``Comments to Docket 
Number 97-NM-19-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. 97-NM-19-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    In 1967, the FAA issued AD 67-17-05, amendment 39-511 (32 FR 7248, 
May 16, 1967), applicable to certain Gulfstream Model G-159 airplanes, 
to require repetitive visual inspections to detect chafe wear on the 
upper diagonal engine mount tubes, part number (P/N) 159W10172-11 (left 
engine) and P/N 159W10172-13 (right engine). Depending upon the depth 
of wear found during any inspection, the AD requires that the tube(s) 
either be replaced or repaired, and the repetitive visual inspections 
continued thereafter at intervals of 200 hours time-in-service.
    That AD also provides for optional terminating action for these 
visual inspections, which consists of installing a chafe guard (P/N 
159WP10017-11) on each of the upper diagonal trusses. If an operator 
elects to install these chafe guards, the AD requires that the chafe 
guards be repetitively inspected to detect wear thereafter at intervals 
of 2,500 hours time-in-service.
    That action was prompted by reports of excessive chafe wear found 
on the engine mount tubes on some airplanes. The chafe wear was 
determined to be caused by the tube coming into contact with the engine 
exhaust tail pipe blanket. The requirements of that AD are intended to 
detect and correct chafe wear of the engine mount tube; if such wear is 
left unchecked, it could result in the failure of the engine mount 
assembly and possible separation of the engine from the airplane.

Actions Since Issuance of Previous Rule

    As part of its on-going program to address issues relevant to the 
continued operational safety of the aging transport fleet, the FAA, 
along with Gulfstream Aerospace Corporation and several U.S. and non-
U.S. operators of the affected airplanes, agreed to undertake the task 
of identifying and implementing procedures to ensure the continuing 
structural airworthiness of aging commuter class airplanes. This group 
recently reviewed selected customer bulletins and aircraft service 
changes, applicable to Gulfstream Model G-159 airplanes, to be 
recommended for mandatory rulemaking action to ensure the continued 
operational safety of these airplanes.

Explanation of Relevant Service Information

    The group reviewed and recommended Grumman Gulfstream I Aircraft 
Service Change No. 180, dated October 17, 1966, for mandatory 
regulatory action. That service change describes procedures for a one-
time initial inspection to detect chafe wear of the upper diagonal 
trusses [P/N 159W10172-5 (left-hand nacelle) and P/N 159W10172-7 
(right-hand nacelle), and replacement of worn parts, if necessary.
    The service change also describes procedures for installing chafe 
guards [part number 159WP10017-11] after the inspection of the trusses 
is accomplished. The chafe guards are intended to provide better 
protection of the subject area against future chafe wear. Once these 
chafe guards are installed, the service change recommends that an 
inspection of the chafe guards be conducted thereafter at intervals of 
2,500 hours time-in-service.
    (The installation of the chafe guards and continuing inspections, 
as described in this service change, are the same actions that were 
provided as optional terminating action for the visual inspections of 
the engine mount tubes in AD 67-17-05.)

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 supersede AD 67-17-05. It would continue to require 
the repetitive visual inspections to detect chafe wear of the engine 
mount tube, and repair or replacement of the tube(s), if necessary. 
These inspections would be required to continue until (1) a one-time 
inspection is performed to detect chafe wear of the upper diagonal 
truss, and (2) chafe guards are installed. (Once the chafe guards are 
installed, the previously required visual inspections of the engine 
mount tubes would be terminated.) The proposed AD also would require 
that, after the chafe guards are installed, an inspection of the chafe 
guards be conducted at intervals of 2,500 hours time-in-service. These 
actions would be required to be accomplished in accordance with the 
aircraft service change described previously.

Cost Impact

    There are approximately 146 Gulfstream Model G-159 airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 72 
airplanes of U.S. registry would be affected by this proposed AD.
    The actions that are currently required by AD 67-17-05 take 
approximately 4 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the currently required actions on U.S. operators is estimated 
to be $17,280, or $240 per airplane, per inspection.
    The installation of the chafe guards that is proposed in this AD 
action would take approximately 40 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts would cost approximately $152 per airplane. Based on these 
figures, the cost impact of the proposed requirements of this AD on 
U.S. operators is estimated to be $183,744, or $2,552 per airplane.
    The inspections of the chafe guards that are proposed in this AD 
action would take approximately 4 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the currently required actions on 
U.S. operators is estimated to be $17,280, or $240 per airplane, per 
inspection.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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

[[Page 10228]]

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 removing amendment 39-511 (32 FR 
7248, May 16, 1967), and by adding a new airworthiness directive (AD), 
to read as follows:

Gulfstream Aerospace Corporation (formerly Grumman): Docket 97-NM-
19-AD. Supersedes AD 67-17-05, Amendment 39-511.

    Applicability: All Model G-159 (G-I) 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 
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 (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 excessive chafe wear of the engine mount tube and 
upper diagonal truss, which could lead to failure of the engine 
mount assembly and possible separation of the engine from the 
airplane, accomplish the following:
    (a) For airplanes on which chafe guards, P/N 159WP10017-11, have 
not been installed on each upper diagonal truss prior to the 
effective date of this AD: Accomplish paragraphs (a)(1), (a)(2), and 
(a)(3) of this AD:
    (1) Restatement of Requirements of AD 67-17-05: Within 100 hours 
time-in-service after May 16, 1967 (the effective date of AD 67-17-
05, amendment 39-411), visually inspect to detect chafe wear of the 
lower half of the upper diagonal engine mount tubes having part 
number (P/N) 159W10172-11 (left engine) and P/N 159W10172-13 (right 
engine).
    (i) If no chafe wear is detected: Repeat this inspection 
thereafter at intervals not to exceed 200 hours time-in-service 
until the requirements of paragraph (a)(2) are accomplished.
    (ii) If any tube is found to have wear depth greater than 0.030 
inch (as measured from the outer edge of the tube): Prior to further 
flight, replace the tube with a tube of the same part number or with 
an FAA-approved equivalent part. After replacement, repeat the 
inspection required by this paragraph at intervals not to exceed 200 
hours time-in-service until the requirements of paragraph (a)(2) are 
accomplished.
    (iii) If any tube is found to have wear depth of 0.030 inch deep 
or less, as measured from the outer edge of the tube: Prior to 
further flight, either repair the tube in accordance with an FAA-
approved repair, or replace the tube with a part of the same part 
number or with an FAA-approved equivalent part. After repair or 
replacement, repeat the inspection required by this paragraph at 
intervals not to exceed 200 hours time-in-service until the 
requirements of paragraph (a)(2) are accomplished.
    (2) One-Time Inspection of Upper Diagonal Truss and Installation 
of Chafe Guards. Within 600 hours time-in-service after the 
effective date of this AD, perform a one-time visual inspection to 
detect chafe wear of the left-hand and right-hand upper diagonal 
truss, P/N's 159W10172-5 (left-hand nacelle) and P/N 159W10172-7 
(right-hand nacelle), in accordance with Grumman Gulfstream Service 
Change No. 180, dated October 17, 1966. Once this inspection is 
completed, the repetitive inspections required by paragraph (a)(1) 
of this AD may be terminated.
    (i) If there is no evidence of chafe wear on the truss; or if 
there is evidence of chafe wear and the depth of wear is .030 inch 
or less (measured from the surface of the tube): Prior to further 
flight, install a chafe guard, P/N 159WP10017-11, on the truss.
    (ii) If there is any evidence of chafe wear and the depth of 
wear exceeds .030 inch measured (from the surface of the tube): 
Prior to further flight, install a new upper diagonal truss and 
install a chafe guard, P/N 159WP10017-11, on the truss.
    (3) Continuing Inspections of Chafe Guards. Within 2,500 hours 
time-in-service after installation of the chafe guards required by 
paragraph (a)(2) of this AD, perform an inspection of the 
undersurface of each chafe guard for evidence of chafe wear, in 
accordance with Grumman Gulfstream Service Change No. 180, dated 
October 17, 1966.
    (i) If no chafe wear is detected: Repeat the inspection at 
intervals not to exceed 2,500 hours time-in-service.
    (ii) If any chafe wear is detected: Prior to further flight, 
replace the chafe guard with a new or serviceable part. After 
replacement, repeat the inspection for chafe wear of the chafe guard 
thereafter at intervals not to exceed 2,500 hours time-in-service.
    (b) For airplanes on which chafe guards, P/N 159WP10017-11, have 
been installed on each upper diagonal truss prior to the effective 
date of this AD: Within 2,500 hours time-in-service after the last 
inspection of the chafe guard required by paragraph (c) of AD 67-17-
05, repeat that inspection to detect chafe wear of the chafe guards 
in accordance with Grumman Gulfstream Service Change No. 180, dated 
October 17, 1966.
    (1) If no chafe wear is detected: Repeat the inspection 
thereafter at intervals not to exceed 2,500 hours time-in-service.
    (2) If any chafe wear is detected: Prior to further flight, 
replace the chafe guard with a new or serviceable part. After 
replacement, repeat the inspection thereafter at intervals not to 
exceed 2,500 hour time-in-service.
    (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 2: 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 February 27, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-5462 Filed 3-5-97; 8:45 am]
BILLING CODE 4910-13-U