[Federal Register Volume 63, Number 241 (Wednesday, December 16, 1998)]
[Rules and Regulations]
[Pages 69177-69178]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-33106]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 63, No. 241 / Wednesday, December 16, 1998 /
Rules and Regulations
[[Page 69177]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-SW-29-AD; Amendment 39-10943; AD 98-26-02]
Airworthiness Directives; Sikorsky Aircraft Corporation Model S-
61A, D, E, L, N, NM, R, and V 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 Corporation Model S-61A, D, E, L, N,
NM, R, and V helicopters, that requires a nondestructive inspection
(NDI) for cracks in the main rotor shaft (shaft), and requires removal
of any shaft with a crack and replacement with an airworthy shaft. This
AD also requires appropriate marking of shafts and log book entries by
the operator to determine the shaft retirement life, and establishes a
new retirement life for the shaft. This amendment is prompted by four
reports of cracks occurring in helicopters that were utilized in
repetitive external lift (REL) operations. The actions specified by
this AD are intended to detect a fatigue crack in the shaft that could
result in shaft structural failure, loss of power to the main rotor,
and subsequent loss of control of the helicopter.
DATES: Effective January 20, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of January 20, 1999.
ADDRESSES: The service information referenced in this AD may be
obtained from Sikorsky Aircraft Corporation, Attn: Manager, Commercial
Tech Support, 6900 Main Street, P.O. Box 9729, Stratford, CT 06497-
9129. This information may be examined at the FAA, Office of the
Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort
Worth, Texas 76137; or at the Office of the Federal Register, 800 North
Capitol Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT:
Wayne Gualzetti, Aerospace Engineer, ANE-150, 12 New England Executive
Park, Burlington, MA 01803, telephone (781) 238-7156, fax (781) 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 Corporation
Model S-61A, D, E, L, N, NM, R, and V helicopters was published in the
Federal Register on September 18, 1997 (62 FR 48961). That action
proposed to require a NDI of the shaft, part number (P/N) S6135-20640-
001, S6135-20640-002, or S6137-23040-001, used in REL operations within
the next 1,000 hours time-in-service (TIS). The NDI must be performed
in accordance with the Overhaul Manual. That action also proposed to
establish retirement lives for certain shafts utilized in REL
operations. For shafts installed on helicopters utilized in REL
operations that have not been modified in accordance with Sikorsky
Customer Service Notice (CSN) 6135-10, dated March 18, 1987, and
Sikorsky Alert Service Bulletin (ASB) No. 61B35-53, dated December 2,
1981, the retirement life would be 1,500 hours TIS. For shafts
installed on helicopters utilized in REL operations that have been
modified in accordance with Sikorsky CSN 6135-10, dated March 18, 1987,
and Sikorsky ASB No. 61B35-53, dated December 2, 1981, the retirement
life would be 2,000 hours TIS.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Several commenters state that the cost of a replacement shaft,
which is $44,753, should be stated in the AD to indicate the severity
of the cost impact this AD will have on owners and operators. The FAA
concurs and will include the cost of the shaft in the AD.
One commenter states that issuance of the AD is unnecessary
because, over a period of 38 years, there have been only two
occurrences of shaft cracks. The FAA does not concur. There have been a
total of four reported instances of cracked shaft flanges. All four
shafts were used in REL operations. Subsequent tests conducted by the
manufacturer confirmed the failure due to REL cycles and the need for
the life limitation.
The same commenter states that the AD should be applicable to Model
CH-3C, CH-3E, HH-3C, and HH-3E helicopters. The FAA concurs since these
restricted category helicopters are equipped with the same main gearbox
and shaft. These models will be the subject of future rulemaking
action.
Two commenters state that the proposed retirement life should be
increased from 2,000 hours TIS to 2,500 hours TIS. The change is
requested so that the shaft retirement time will be in line with
existing gearbox overhaul requirements. The FAA partially concurs. This
change will allow the shaft replacement to be conducted concurrently
with any recommended gearbox overhaul actions. Based on a further
evaluation of the dowel pin cracking and the fretting cracking, the FAA
has determined that the retirement life can safely be increased from
the proposed 2,000 hours TIS to 2,200 hours TIS. This will allow
operators to get two overhaul cycles of 1,100 hours TIS for each shaft
used in REL operations. Therefore, the retirement life is extended from
2,000 hours TIS to 2,200 hours TIS for shafts that have been modified
in accordance with the Sikorsky service information described
previously. This change also will allow operators to avoid excessive
disassembly and re-assembly of the gearbox for overhauls and shaft
removal based on an approved 1,100 hours TIS gearbox overhaul cycle.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes described
previously. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
The FAA estimates that 30 helicopters of U.S. registry that are
involved in REL operations will be affected by this AD, that it will
take approximately 2.2 work hours per helicopter to accomplish the
[[Page 69178]]
required actions during the next scheduled overhaul, and that the
average labor rate is $60 per work hour. Required parts will cost
approximately $50 for the inspection and $44,753 for each shaft. Based
on these figures, the total cost impact of the AD on U.S. operators is
estimated to be $1,348,050, assuming all 30 shafts are replaced.
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. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
to read as follows:
AD 98-26-02 Sikorsky Aircraft Corporation: Amendment 39-10943.
Docket No. 96-SW-29-AD.
Applicability: Model S-61A, D, E, L, N, NM, R, and V
helicopters, with main rotor shaft (shaft), part number (P/N) S6135-
20640-001, S6135-20640-002, or S6137-23040-001, 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 (e) 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 change
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 detect a fatigue crack in the shaft that could result in
shaft structural failure, loss of power to the main rotor, and
subsequent loss of control of the helicopter, accomplish the
following:
(a) Within the next 30 calendar days or 240 hours time-in-
service (TIS) after the effective date of this AD, whichever occurs
first, determine if the shaft has been used in repetitive external
lift (REL) operations. REL operation is defined as operation during
which the average number of external lifts equals or exceeds six per
flight hour for any 250 hour TIS period during the main gearbox
overhaul interval. An external lift is defined as a flight cycle in
which an external load is picked up, the helicopter is repositioned
(through flight or hover), and the helicopter hovers and releases
the load and departs or lands and departs. Record the total number
of hours TIS during which external lifts have been conducted, as
well as the number of external lifts conducted during each hour, on
the component log card or equivalent record. If the number of
external lifts cannot be determined, assume 6 external lifts were
conducted during each hour TIS in which external lifts were
conducted. If the hours TIS of external lift operations cannot be
determined, assume REL operations were conducted.
(b) For shafts used in REL operations, within the next 1,100
hours TIS after the effective date of this AD, conduct a non-
destructive inspection (NDI) for cracks in the shaft in accordance
with the Overhaul Manual. If a crack is discovered in a shaft,
remove the shaft and replace it with an airworthy shaft. Mark the
removed airworthy shafts and the replacement shafts in accordance
with the Accomplishment Instructions in paragraphs 2E and 2f of
Sikorsky Aircraft Corporation Alert Service Bulletin (ASB) No.
61B35-68, dated July 19, 1996. Once a shaft has been designated and
marked as an REL shaft, it is life-limited accordingly for the
remainder of that shaft's airworthy service life.
(c) Retire all shafts that have been used in REL operations as
follows:
(1) Shafts that have been modified in accordance with Sikorsky
Customer Service Notice 6135-10, dated March 18, 1997, and Sikorsky
ASB No. 61B35-53, dated December 2, 1981 (modified REL shafts), must
be removed from service on or before attaining 2,200 hours TIS.
(2) Shafts that have not been modified in accordance with
Sikorsky Customer Service Notice 6135-10, dated March 18, 1987, and
Sikorsky ASB 61B35-53, dated December 1981 (unmodified REL shafts),
must be removed from service on or before attaining 1,500 hours TIS.
(d) This AD revises the Limitations section of the maintenance
manual by establishing new retirement lives of 1,500 hours TIS for
unmodified REL shafts and 2,200 hours TIS for modified REL shafts.
(e) 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, Boston Aircraft Certification
Office. 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.
(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 helicopter to a location where
the requirements of this AD can be accomplished.
(g) The marking of the shaft shall be done in accordance with
Sikorsky Aircraft Corporation Alert Service Bulletin No. 61B35-68,
dated July 19, 1996. 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 Corporation, Attn: Manager, Commercial Tech Support, 6900
Main Street, P.O. Box 9729, Stratford, CT 06497-9129. Copies may be
inspected at the FAA, Office of the Regional Counsel, Southwest
Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
(h) This amendment becomes effective on January 20, 1999.
Issued in Forth Worth, Texas, on December 7, 1998.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 98-33106 Filed 12-15-98; 8:45 am]
BILLING CODE 4910-13-U
