[Federal Register Volume 62, Number 44 (Thursday, March 6, 1997)]
[Proposed Rules]
[Pages 10228-10231]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5461]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 97-NM-16-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 modification and
repetitive inspections for cracks in the main landing gear (MLG)
retract cylinder attachment fittings. This action would require the
installation of improved attachment fittings which, when accomplished,
[[Page 10229]]
would terminate the requirement for the repetitive inspections. This
proposal is prompted by the development of a modification that
positively addresses the identified unsafe condition. The actions
specified by the proposed AD are intended to prevent failure of the MLG
retract cylinder attachment fitting due to fatigue cracking. That
condition, if not corrected, could result in the inability to retract
the MLG.
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-16-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 postcard on which the following statement is made: ``Comments
to Docket Number 97-NM-16-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-16-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
In 1967, the FAA issued AD 67-31-08, amendment 39-515 (32 FR 16201,
November 28, 1967), applicable to certain Gulfstream Model G-159
airplanes, to require repetitive visual and dye penetrant inspections
for cracks in the main landing gear (MLG) retract cylinder attachment
fittings, part number (P/N) 159WM10032-1 and -2, located on the lower
surface of the left-hand and right-hand wings; and replacement of
cracked parts. It also requires that the fittings be modified by
rounding off their aft end edges.
AD 67-31-08 also provided for an optional terminating action, which
consisted of replacing the MLG retract cylinder attachment fittings
with improved fittings, having Grumman P/N 159WM10276-1 and -2, and
balls having Grumman P/N 159WM10277-1.
That action was prompted by a report indicating that, during a
routine inspection, the MLG retract cylinder attachment fitting on one
airplane was found to be cracked through the aft end. Examination of
the fitting revealed several notches located along one edge in the area
where the failure had occurred. This cracking in the fitting was
determined to be due to fatigue that could be directly attributed to
these notches.
The requirements of that AD are intended to prevent failure of the
MLG retract cylinder attachment fitting due to fatigue cracking. This
condition, if not corrected, could result in the inability to retract
the MLG.
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
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 Service
Change No. 184, dated February 1, 1968, and Amendment 1 to that Service
Change, dated June 28, 1968, for mandatory rulemaking action. This
service information describes procedures for removing MLG retract
cylinder attachment fitting assemblies made of aluminum alloy and
having P/N 159WM10032-1 and -2, and replacing them with fitting
assemblies made of steel and having P/N 159WM10276-1 and -2 and balls
having P/N 159WM10277-1. Installation of steel assemblies will preclude
the potential for fatigue cracking to occur in the fittings.
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 67-31-08. It would continue to require
the repetitive inspections and modification of the MLG retract cylinder
attachment fittings, and replacement, if necessary. This new action
would require that the attachment fitting assemblies eventually be
replaced with assemblies made of steel. Once this replacement is
accomplished, the previously required modification and inspections may
be terminated. The replacement action would be required to be
accomplished in accordance with the service information described
previously.
FAA's Determination for the Need to Mandate the Replacement
The FAA has determined that long term continued operational safety
will be better assured by design changes to remove the source of the
problem, rather than by repetitive inspections. Long term inspections
may not be providing the degree of safety assurance necessary for the
transport airplane fleet. This, coupled with a better understanding of
the human factors associated with numerous continual inspections, has
led
[[Page 10230]]
the FAA to consider placing less emphasis on inspections and more
emphasis on design improvements. The proposed replacement requirement
is in consonance with these considerations.
Cost Impact
There are approximately 146 Gulfstream Model G-159 (G-I) 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 67-31-08 take
approximately 3 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 $12,960, or $180 per airplane, per inspection.
The replacement action that is proposed in this AD action would
take approximately 45 work hours per airplane to accomplish, at an
average labor rate of $60 per work hour. Required parts would cost
approximately $5,400 per airplane. Based on these figures, the cost
impact of the proposed requirements of this AD on U.S. operators is
estimated to be $583,200, or $8,100 per airplane.
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 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 39-515 (32 FR
16201, November 28, 1967), and by adding a new airworthiness directive
(AD), to read as follows:
Gulfstream Aerospace Corporation (formerly Grumman): Docket 97-NM-
16-AD. Supersedes AD 67-31-08, amendment 39-515.
Applicability: Model G-159 (G-I) airplanes; serial numbers (S/N)
1 through 12 inclusive, 14 through 112 inclusive, 114 through 148
inclusive, 322, and 323; on which main landing gear cylinder attach
fitting assemblies having part number (P/N) 159WM10276-1 and -2 and
balls having P/N 159WM10277-1 are not installed; 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)(1)
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 failure of the main landing gear (MLG) retract
cylinder attachment fittings due to fatigue cracking, which could
result in the inability to retract the MLG, accomplish the
following:
(a) Accomplish the actions specified in paragraphs (a)(1) and
(a)(2) of this AD, at the times indicated in those paragraphs and in
accordance with Grumman Gulfstream Customer Bulletin No. 172, dated
September 6, 1963.
(1) Beginning November 7, 1967 (the effective date of AD 67-31-
08, amendment 39-515), and prior to each flight, conduct a visual
inspection to detect cracks in the MLG retract cylinder attachment
fittings on the lower surface of the right-hand and left-hand wings
in the vicinity of the aft end of the fitting.
(2) Within 25 hours time-in-service after November 7, 1967,
accomplish the actions specified in paragraphs (a)(2)(i) and
(a)(2)(ii) of this AD:
(i) Conduct a dye penetrant inspection, in conjunction with at
least a 10X magnifying glass, to detect cracks in the MLG retract
cylinder attachment fittings on the lower surface of the right-hand
and left-hand wings in the vicinity of the aft end of the fitting.
Repeat this inspection thereafter at intervals not to exceed 25
hours time-in-service. And
(ii) Modify the aft end edges of the fitting by rounding them
off to approximately 1/32'' radius.
(b) If any crack is found during an inspection required by
paragraph (a) of this AD, prior to further flight, accomplish either
paragraph (b)(1) or (b)(2) of this AD:
(1) Replace the cracked part with a part of the same part number
that has been modified and inspected in accordance with paragraph
(a) of this AD, in accordance with Grumman Gulfstream Customer
Bulletin No. 172, dated September 6, 1963. Thereafter, continue the
inspections required by paragraph (a) of this AD. Or
(2) Replace the fitting assembly with an assembly having part
number (P/N) 159WM10276-1 or -2, and balls having P/N 159WM10277-1.
After accomplishing this replacement, the repetitive inspections of
that fitting required by paragraph (a) of this AD may be terminated.
(c) Within 400 hours time-in-service after the effective date of
this AD, replace the MLG retract cylinder attachment fitting
assemblies with assemblies having part numbers (P/N) 159WM10276-1
and -2, and balls having P/N 159WM10277-1. This replacement
constitutes terminating action for the inspection requirements of
this AD.
(d)(1) 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.
(2) Alternative methods of compliance, approved previously in
accordance with AD 67-31-08, amendment 39-515, are approved as
alternative methods of compliance with this AD.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Atlanta ACO.
(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.
[[Page 10231]]
Issued in Renton, Washington, on February 27, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-5461 Filed 3-5-97; 8:45 am]
BILLING CODE 4910-13-U
