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[Federal Register Volume 62, Number 44 (Thursday, March 6, 1997)]
[Proposed Rules]
[Pages 10231-10233]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5460]

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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 97-NM-15-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 cracking in the mounting lugs of the elevator trim tab 
actuators, and replacement, if necessary. This action would require the 
installation of improved elevator trim tab actuators that are not 
susceptible to the subject cracking. 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 mounting lugs on the elevator trim tab 
actuator due to cracking; such failure could result in severe vibration 
during flight and/or reduction or loss of elevator trim tab capability, 
which could lead to reduced controllability of 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-15-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-15-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-15-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    In 1972, the FAA issued AD 72-24-04, amendment 39-1559 (37 FR 
24419, November 17, 1972), applicable to certain Gulfstream Model G-
159'' airplanes (formerly designated as ``Grumman Gulfstream G-159'' 
airplanes), to require:
    1. repetitive dye penetrant inspections to detect cracking in the 
mounting lugs of the elevator trim tab actuator, part number (P/N) 
159SCC100-1 and -5; and
    2. shimming to correct any out-of-plane mounting.
    If cracking is detected during any inspection, the AD requires that 
the actuator be replaced with an actuator having P/N 159SCC100-1, -5, 
or -11. (AD 72-24-04 specifies that, if an actuator having P/N 
159SCC100-11 is installed, no further action is required.)
    That action was prompted by a report indicating that, during an 
inspection, all four mounting lugs on a Gulfstream G-159 elevator trim 
tab actuator were found to be cracked. Examination of the actuator unit 
indicated that two of the lugs had been failed for an undetermined 
period of time. Additional inspections of other airplanes revealed 
numerous fittings with one lug failed and some with two lugs failed.
    Once one lug fails, the adjacent lug is under twice the normal 
stress, and will eventually fail. At that point, the remaining two lugs 
are being worked in bending and their remaining service life, in this 
condition, is short.
    The requirements of that AD are intended to detect cracked lugs as 
early as possible so as to prevent the concurrent failure of the four 
lugs. Such failure could cause severe vibration during flight and/or 
reduction or loss of elevator trim tab capability; this could then 
result in reduced controllability of 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 
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. 191, dated August 18, 1972, for mandatory rulemaking 
action. This service change describes procedures for replacing the 
elevator trim tab actuators having P/N 159SCC100-1 or -5, with 
actuators having P/N 159SCC100-11. The replacement actuators have new, 
increased strength housings, and are not susceptible to the type of 
cracking that

[[Page 10232]]

was previously found. Installation of these new actuators eliminates 
the need for the repetitive inspections for cracking.
    The group recognized the fact that cracks in the existing elevator 
trim tab actuator housings are very difficult to identify, even with 
the dye penetrant, if they are small or have just started. Therefore, 
installation of the improved actuators will positively address the 
identified unsafe condition by eliminating the potential both for the 
cracking itself, as well as for cracks that are missed during an 
inspection.

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 72-24-04. It would continue to require 
the repetitive dye penetrant inspections for cracks in the elevator 
trim tab actuator mounting lugs. However, it would also require the 
installation of improved actuators, which would constitute terminating 
action for the repetitive inspections. The installation would be 
required to be accomplished in accordance with the aircraft service 
change described previously.

FAA's Determination for the Need to Mandate the Installation

    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 the FAA to consider placing less emphasis on inspections and more 
emphasis on design improvements. The proposed installation requirement 
is in consonance with these considerations.

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 inspections that are currently required by AD 72-24-04 take 
approximately 2 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 $8,640, or $120 per airplane, per inspection.
    The new installation that is proposed in this AD action would take 
approximately 12 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $4,900 per airplane. Based on these figures, the cost 
impact of the proposed requirements of this AD on U.S. operators is 
estimated to be $404,640, or $5,620 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.

39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-1559 (37 FR 
24419, November 17, 1972), and by adding a new airworthiness directive 
(AD), to read as follows:

Gulfstream Aerospace Corporation (previously Grumman): Docket 97-NM-
15-AD. Supersedes AD 72-24-04, amendment 39-1559.

    Applicability: Model G-159 (G-I) airplanes, on which elevator 
trim tab actuators having part number 159SCC100-11 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 (e)(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 elevator trim tab mounting lugs due to 
cracking, which could result in severe vibration during flight and a 
consequent reduction or loss of elevator trim tab capability, 
accomplish the following:
    (a) Within 10 hours time-in-service after November 24, 1972 (the 
effective date of AD 72-24-04, amendment 39-1559), perform an 
inspection to detect cracks in the mounting lugs of the elevator 
trim tab actuators, having part number (P/N) 159SCC100-1 or -5; and 
shim to correct any out-of-plane condition, in accordance with 
Gulfstream Customer Bulletin No. 208A through Amendment 2, dated 
April 21, 1972, and Operational Summary No. 72-5B, dated August 
1972.
    (b) If no crack is found in any mounting lug during the 
inspection required by paragraph (a) of this AD, repeat the 
inspection at intervals not to exceed 200 hours time-in-service.
    (c) If any crack is found in a mounting lug when conducting any 
inspection required by paragraph (a) or (b) of this AD, prior to 
further flight, replace the elevator trim tab actuator with a new or 
serviceable actuator having P/N 159SCC100-1, -5, or -11.
    (1) If an actuator having P/N 159SCC100-1 or -5 is used as the 
replacement unit, repeat the inspection for cracks specified in 
paragraph (a) of this AD thereafter at intervals not to exceed 200 
hours time-in-service.
    (2) If an actuator having P/N 159SCC100-11 is used as the 
replacement unit, no further inspection action is required for that 
unit in accordance with this AD.
    (d) Within 1,000 hours time-in-service after the effective date 
of this AD, replace the

[[Page 10233]]

elevator trim tab actuators with actuators that have P/N 159SCC100-
11, in accordance with Gulfstream Aircraft Service Change No.191, 
dated August 18, 1972. This installation constitutes terminating 
action for the inspections required by this AD.
    (e)(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 72-24-02, amendment 39-1559, 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.

    (f) 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. 97-5460 Filed 3-5-97; 8:45 am]
BILLING CODE 4910-13-U
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