[Federal Register Volume 61, Number 199 (Friday, October 11, 1996)]
[Proposed Rules]
[Pages 53337-53339]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-26128]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-SW-34-AD]


Airworthiness Directives; Sikorsky Aircraft-Manufactured Model S-
64F Helicopters

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 Sikorsky Aircraft-manufactured S-
64F helicopters. This proposal would require inspections, and 
replacement, if necessary, of the main gearbox second stage lower 
planetary plate (plate). This proposal is prompted by two incidents in 
which the second stage planetary plate was found cracked. The actions 
specified by the proposed AD are intended to prevent failure of the 
plate due to fatigue cracking, which could lead to failure of the main 
gearbox and subsequent loss of control of the helicopter.

DATES: Comments must be received by December 10, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 95-SW-34-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137. 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 Erickson Air-Crane Co., 3100 Willow Springs Rd., P.O. Box 
3247, Central Point, Oregon 97502. This information may be examined at 
the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., 
Room 663, Fort Worth, Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Uday Garadi, Aerospace Engineer, 
FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 2601 
Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5114, fax 
(817) 222-5961.

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 should 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.

[[Page 53338]]

    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 No. 95-SW-34-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, Office of the Assistant Chief Counsel, Attention: Rules 
Docket No. 95-SW-34-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 
76137.

Discussion

    This document proposes the adoption of a new AD that is applicable 
to Model S-64F helicopters. During the overhaul of a main gearbox 
assembly, Erickson Air-Crane Co., the type certificate holder, found a 
plate that was cracked. Subsequent field boroscope inspections 
performed on other S-64F helicopters revealed a second plate that was 
also cracked. This condition, if not corrected, could lead to failure 
of the plate due to fatigue cracking, which could lead to failure of 
the main gearbox and subsequent loss of control of the helicopter.
    The FAA has reviewed Erickson Air-Crane Co. Service Bulletin No. 
64F35-2A, which describes procedures for the inspection and 
replacement, if necessary, of the plate.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Sikorsky Aircraft-manufactured Model S-64F 
helicopters of the same type design, the proposed AD would require a 
daily inspection of main gearboxes containing a plate with more than 
2,000 hours time-in-service (TIS) for main gearbox oil filter magnesium 
contamination and, if magnesium contamination is discovered, 
replacement of the main gearbox assembly. For main gearbox assemblies 
containing a plate with more than 2,000 hours TIS, this AD also 
requires an inspection of the plate within the next 100 hours TIS after 
the effective date of this AD, and thereafter at intervals not to 
exceed 500 hours TIS; and replacement of the plate if necessary. This 
AD also requires, at the next overhaul of the main gearbox assembly, 
inspection and rework of plates that are not cracked. The actions would 
be required to be accomplished in accordance with the service bulletin 
described previously.
    The FAA estimates that 6 helicopters of U.S. registry would be 
affected by this proposed AD, that it would take approximately 8 work 
hours per helicopter to accomplish the borescope inspection and 140 
work hours to remove and replace the main gearbox assembly, if 
necessary, and that the average labor rate is $60 per work hour. 
Required parts would cost $8,000. Based on these figures, the total 
cost impact of the proposed AD on U.S. operators is estimated to be 
$101,280; $2,880 to accomplish the inspections, and $98,400 to replace 
the plate in the main gearbox assembly in all 6 helicopters, if 
necessary.
    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 adding a new airworthiness directive 
to read as follows:

Erickson Air-Crane Co.: Docket No. 95-SW-34-AD.

    Applicability: Sikorsky Aircraft-manufactured Model S-64F 
helicopters, with main gearbox second stage lower planetary plate, 
part number (P/N) 6435-20516-101 installed, 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 (c) 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 main gearbox second stage lower 
planetary plate (plate) due to fatigue cracking, which could lead to 
failure of the main gearbox and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) For main gearbox assemblies containing plate, P/N 6435-
20516-101, with 2,000 hours time-in-service (TIS) or more:
    (1) Prior to the first flight of each day, inspect the main oil 
filter for magnesium contamination, and if magnesium contamination 
is discovered, replace the main gearbox assembly.
    (2) Within the next 100 hours TIS after the effective date of 
this AD, and thereafter at intervals not to exceed 500 hours TIS, 
inspect or replace the main gearbox assembly in accordance with the 
Accomplishment Instructions of Section 2, Paragraph B, of Erickson 
Service Bulletin No. 64F35-2A dated November 8, 1995.
    (b) At the next overhaul of the main gearbox assembly, inspect 
and rework the plate, P/N 6435-20516-101, in accordance with Section 
2, Paragraphs C(1) and (3) through (11) of Erickson Service Bulletin 
No. 64F35-2A, dated November 8, 1995.
    (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, Rotorcraft Certification Office, 
Rotorcraft Directorate, FAA. Operators shall submit their requests 
through an FAA Principal Maintenance Inspector, who may concur or 
comment and then send it to the Manager, Rotorcraft Certification 
Office.

    Note 2: Information concerning the existence of approved 
alternative methods of

[[Page 53339]]

compliance with this AD, if any, may be obtained from the Rotorcraft 
Certification Office.

    (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 helicopter to a location where 
the requirements of this AD can be accomplished.

    Issued in Fort Worth, Texas, on October 4, 1996.
Eric Bries,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 96-26128 Filed 10-10-96; 8:45 am]
BILLING CODE 4910-13-U