[Federal Register Volume 60, Number 92 (Friday, May 12, 1995)]
[Rules and Regulations]
[Pages 25611-25612]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11539]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-SW-18-AD; Amendment 39-9226; AD 95-10-09]


Airworthiness Directives; Sikorsky Aircraft Model S-58 and S-58T 
Series Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to Sikorsky Aircraft Model S-58 and S-58T series 
helicopters, that requires the removal and replacement of the 
transmission main gear box ring gear (ring gear) within certain time 
intervals, and establishes a retirement life for the ring gear. This 
amendment is prompted by reports of failures of the ring gear due to 
slow-growth fatigue cracks. The actions specified by this AD are 
intended to prevent failure of the ring gear, failure of the main 
transmission, and subsequent loss of control of the helicopter.

DATES: Effective June 16, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 16, 1995.

ADDRESSES: The service information referenced in this AD may be 
obtained from Sikorsky Aircraft, Commercial Customer Support, 6900 Main 
Street, Stratford, Connecticut 06601-1381. This information may be 
examined at the FAA, Office of the Assistant Chief Counsel, 2601 
Meacham Boulevard, Room 663, Fort Worth, Texas; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Mr. Francis X. Walsh, Aerospace 
Engineer, Boston Aircraft Certification Office, FAA, New England 
Region, 12 New England Executive Park, Burlington, Massachusetts 01803-
5299, telephone (617) 238-7158, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to Sikorsky Aircraft Model S-58 and 
S-58T series [[Page 25612]] helicopters was published in the Federal 
Register on June 22, 1994 (59 FR 32144). That action proposed to 
require the removal and replacement of the ring gear within certain 
time intervals, and proposed to establish a retirement life for the 
ring gear.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposal or the FAA's determination of the cost to the public. The FAA 
has determined that air safety and the public interest require the 
adoption of the rule as proposed. Since the issuance of the proposed 
rule, the FAA has revised the average labor rate from $55 per work hour 
to $60 per work hour, which increases the estimated cost impact on 
operators to $486,250.
    The FAA estimates that 125 helicopters of U.S. registry will be 
affected by this AD, that it will take approximately 31.5 work hours 
per helicopter to accomplish the required actions, and that the average 
labor rate is $60 per work hour. Required parts will cost approximately 
$2,000 per helicopter. Based on these figures, the total cost impact of 
the AD on U.S. operators is estimated to be $486,250.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

95-10-09  Sikorsky Aircraft: Amendment 39-9226. Docket No. 93-SW-18-
AD.

    Applicability: Model S-58 and S-58T series helicopters, 
certificated in any category.

    Note 1: This AD applies to each helicopter 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 helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (d) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the transmission main gear box ring gear 
(ring gear), failure of the main transmission, and subsequent loss 
of control of the helicopter, accomplish the following:
    (a) Within the next 25 hours time-in-service (TIS) after the 
effective date of this AD, accomplish the following:
    (1) From component records, determine the TIS for the ring gear, 
part number (P/N) S1635-20058-2.
    (i) If the TIS on the ring gear is 2,400 or more hours on the 
effective date of this AD, replace it with an airworthy serialized 
ring gear within the next 100 hours TIS.
    (ii) If the TIS on the ring gear is less than 2,400 hours on the 
effective date of this AD, replace it with an airworthy serialized 
ring gear at or before reaching 2,500 hours TIS.
    (2) If the TIS on the ring gear cannot be determined, replace it 
in accordance with the time-since-last-overhaul (TSO) as follows:
    (i) If the TSO on the ring gear is 1,150 or more hours on the 
effective date of this AD, replace it with an airworthy serialized 
ring gear within the next 100 hours TIS.
    (ii) If the TSO on the ring gear is less than 1,150 hours on the 
effective date of this AD, replace it with an airworthy serialized 
ring gear at or before reaching 1,250 hours TSO.
    (3) Create a component log and a serial number and apply the 
serial number to the ring gear between the ring gear flanges in 
accordance with Paragraph B of the Accomplishment Instructions of 
Sikorsky Aircraft Alert Service Bulletin No. 58B35-32 (ASB 58B35-
32), dated July 6, 1993.
    (b) Create a component log and a serial number for replacement 
ring gears and apply the serial number to the ring gear between the 
ring gear flanges in accordance with Paragraph B of the 
Accomplishment Instructions of the ASB 58B35-32, dated July 6, 1993, 
prior to installing a replacement ring gear on the helicopter.
    (c) This AD establishes a retirement life of 2,500 hours TIS for 
the ring gear. However, for ring gears with 2,400 or more hours TIS, 
or if the TIS cannot be determined, 1,150 or more hours TSO on the 
effective date of this AD, those ring gears need not be retired 
until on or before the accumulation of an additional 100 hours TIS.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used when approved by the Manager, Boston Aircraft Certification 
Office, FAA. Operators shall submit their requests through an FAA 
Principal Maintenance Inspector, who may concur or comment and then 
send it to the Manager, Boston Aircraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Boston Aircraft Certification Office.

    (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 helicopter to a location where 
the requirements of this AD can be accomplished.
    (f) The removal and replacement shall be done in accordance with 
Sikorsky Aircraft Alert Service Bulletin No. 58B35-32, dated July 6, 
1993. This incorporation by reference was approved by the Director 
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from Sikorsky Aircraft, Commercial 
Customer Support, 6900 Main Street, Stratford, Connecticut 06601-
1381. Copies may be inspected at the FAA, Office of the Assistant 
Chief Counsel, 2601 Meacham Boulevard, Room 663, Fort Worth, Texas; 
or at the Office of the Federal Register, 800 North Capitol Street, 
NW., suite 700, Washington, DC.
    (g) This amendment becomes effective on June 16, 1995.

    Issued in Fort Worth, Texas, on May 4, 1995.

Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-11539 Filed 5-11-95; 8:45 am]
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