AD 2015-26-10

final rule

Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

AD Number: 2015-26-10
Status: final_rule
Effective Date: February 9, 2016
Product Category: aircraft
Docket: Docket No. FAA-2014-0335
FR Citation: 81 FR 147

Applicability

Type	Manufacturer	Model	Details
aircraft	Sikorsky Aircraft Corporation	S-76A	Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters
aircraft	Sikorsky Aircraft Corporation	S-76B	Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters
aircraft	Sikorsky Aircraft Corporation	S-76C	Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

Unsafe Condition

Unsecured jet bore liners that have protruded, leading to MGB low oil pressure warnings and potential loss of oil in the MGB, which could result in failure of the MGB and subsequent loss of control of the helicopter.

AI-generated summary from the source AD text. Verify against the official source before acting.

Required Actions

Inspect the main gearbox (MGB) lower housing jet bores for leaks, paint or caulk blistering, and liner protrusion. Replace the MGB if there is oil leakage or protrusion of a jet bore liner. Replace the MGB within 3,750 hours time-in-service (TIS).

AI-generated summary from the source AD text. Verify against the official source before acting.

Compliance Time

Within 50 hours time-in-service (TIS) for initial inspection; within 3,750 hours TIS for MGB replacement.

AI-generated summary from the source AD text. Verify against the official source before acting.

Affected Aircraft

Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C helicopters with a main gearbox (MGB) installed that has undergone certain repairs, specifically those with MGB part numbers 76351-09000 series, 76351-09500 series, and 76351-09600 series, and repaired in accordance with Sikorsky ORI No. 76350-065 or earlier revisions.

AI-generated summary from the source AD text. Verify against the official source before acting.

Federal Register Abstract

We are adopting a new airworthiness directive (AD) for certain Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, S-76B, and S-76C helicopters. This AD requires inspecting the main gearbox (MGB) lower housing jet bores for leaks, paint or caulk blistering, and liner protrusion. This AD was prompted by several reports of MGB low oil pressure warnings which were determined to be the result of unsecured jet bore liners that had protruded. The actions are intended to prevent failure of the MGB from loss of oil, which could result in subsequent loss of control of the helicopter.

Document Text

Show stored source text (verify against official source)

[Federal Register Volume 81, Number 2 (Tuesday, January 5, 2016)]
[Rules and Regulations]
[Pages 147-150]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2015-33013]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2014-0335; Directorate Identifier 2013-SW-021-AD;
Amendment 39-18358; AD 2015-26-10]
RIN 2120-AA64

Airworthiness Directives; Sikorsky Aircraft Corporation
Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, S-76B, and S-76C
helicopters. This AD requires inspecting the main gearbox (MGB) lower
housing jet bores for leaks, paint or caulk blistering, and liner
protrusion. This AD was prompted by several reports of MGB low oil
pressure warnings which were determined to be the result of unsecured
jet bore liners that had protruded. The actions are intended to prevent
failure of the MGB from loss of oil, which could result in subsequent
loss of control of the helicopter.

[[Page 148]]

DATES: This AD is effective February 9, 2016.
The Director of the Federal Register approved the incorporation by
reference of a certain document listed in this AD as of February 9,
2016.

ADDRESSES: For service information identified in this final rule,
contact Sikorsky Aircraft Corporation, Customer Service Engineering,
124 Quarry Road, Trumbull, Connecticut 06611; telephone 1-800-Winged-S
or 203-416-4299; email <a href="/cdn-cgi/l/email-protection#483b2123273a3b23313f2b3b083b2123273a3b2331662b2725">[email&#160;protected]</a>. You may review a copy
of the referenced service information at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321,
Fort Worth, Texas 76177.

Examining the AD Docket

You may examine the AD docket on the Internet at <a href="http://www.regulations.gov">http://www.regulations.gov</a> by searching for or locating Docket No. FAA-2014-
0335; or in person at the Docket Operations Office between 9 a.m. and 5
p.m., Monday through Friday, except Federal holidays. The AD docket
contains this AD, any incorporated-by-reference service information,
the economic evaluation, any comments received, and other information.
The street address for the Docket Operations Office (phone: 800-647-
5527) is U.S. Department of Transportation, Docket Operations Office,
M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue
SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Kirk Gustafson, Aviation Safety
Engineer, Boston Aircraft Certification Office, Engine & Propeller
Directorate, 12 New England Executive Park, Burlington, Massachusetts
01803; telephone (781) 238-7190; email <a href="/cdn-cgi/l/email-protection#472c2e352c692032343326213428290721262669202831">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION:

Discussion

On June 2, 2014, at 79 FR 31231, the Federal Register published our
notice of proposed rulemaking (NPRM), which proposed to amend 14 CFR
part 39 by adding an AD that would apply to Sikorsky Model S-76A, S-
76B, and S-76C helicopters with a MGB installed that has undergone
certain repairs. The NPRM proposed to require, within 50 hours time-in-
service (TIS), inspecting the MGB for leaks, paint or caulk blistering,
and liner protrusion. If there is oil leakage or protrusion of a jet
bore liner, the NPRM proposed to require replacing the MGB before
further flight. The NPRM also proposed to require, within 1,500 hours
TIS, replacing the MGB with an MGB that was not subject to the
applicability of the NPRM unless it had been repaired in accordance
with a later overhaul and repair procedure.
The NPRM was prompted by four reports of protruding jet bore liners
on Sikorsky S-76 helicopters with a MGB, part number (P/N) 76351-09000
series, 76351-09500 series, and 76351-09600 series. During an overhaul
of the MGB, the jet bore liner retaining pins were not adequately
drilled into the liner, allowing the jet bore liner to move in the
housing, because the overhaul and repair instruction (ORI) did not
adequately describe procedures and housing wall thickness limitations
for installing the retaining pins. Movement of the jet bore liner into
the housing allows oil to leak between the liner and the housing,
possibly resulting in loss of oil in the MGB, which could result in
failure of the MGB and subsequent loss of control of the helicopter.
At the time we issued the NPRM, we understood these repairs had
been made in accordance with Sikorsky ORI No. 76350-065, Revisions A
through E. However, the incident MGBs had only been repaired in
accordance with Sikorsky ORI No. 76350-065, Revision A or earlier.
Sikorsky ORI 76350-065, Revisions B through F, resolve the unsafe
condition by clarifying the retaining pin installation instructions.
This AD now reflects that clarification.

Comments

After our NPRM (79 FR 31231, June 2, 2014) was published, we
received comments from one commenter.

Request

Sikorsky stated the proposed requirement to overhaul the affected
MGBs within 1,500 hours TIS is overly conservative because the daily
visual inspection is adequate to ensure safety until the next overhaul
period. Sikorsky further commented that the 1,500 hour compliance time
would be burdensome to operators and not cost effective. When asked for
additional information to support this comment, Sikorsky stated that
its maintenance program has a major inspection, and not a MGB overhaul,
every 1,500 hours. The major inspection does not require removal of the
MGB. Overhaul of the MGB for Model S76A helicopters occurs every 3,250
hours and for Model S76B/C helicopters occurs every 3,750 hours.
We agree. We intended the proposed requirement to provide a
terminating action that coincides with overhaul of the MGB. We
incorrectly understood the 1,500-hour major inspection involved
removing the MGB from the helicopter. We agree that due to the gradual
loss of oil, safety is maintained with the repetitive inspections until
the MGB is replaced or overhauled when specified in the maintenance
program. We have revised paragraph (e)(2) of this AD to require
replacement of the MGB ``within 3,750 hours TIS'' instead of ``within
1,500 hours TIS.''
Sikorsky also commented that limiting acceptable repairs to those
performed in accordance with Sikorksy ORI 76350-065 Revision F was
unnecessary because Revision B and subsequent revisions provide
installation details that are structurally equivalent to Revision F.
When asked for additional information to support this comment, Sikorsky
stated the changes in Revision B clarified the pin retention
instructions sufficiently to resolve the oil leakage issue. Although
Revision F provides for the installation of an additional pin, Sikorsky
stated that this is not a significant change. Sikorsky confirmed that
all reports of oil leakage involved repairs using the procedures in
Revision A or earlier.
We agree. We reexamined Sikorsky ORI No. 76350-065 and its
revisions and found Revisions B through F structurally equivalent with
only minor changes and improvements. We have changed paragraphs (a) and
(e) of this AD to reference the appropriate revisions of Sikorsky ORI
No. 76350-065.

FAA's Determination

We have reviewed the relevant information, considered the comments
received, and determined that an unsafe condition exists and is likely
to exist or develop on other products of these same type designs and
that air safety and the public interest require adopting the AD
requirements as proposed with the changes described previously. These
changes are consistent with the intent of the proposals in the NPRM (79
FR 31231, June 2, 2014), and will not increase the economic burden on
any operator nor increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

Sikorsky issued Alert Service Bulletin (ASB) 76-66-50, Basic Issue,
dated January 14, 2013 (ASB 76-66-50) for Model S-76A, S-76B, and S-76C
helicopters with an MGB P/N 76351-09000 series, 76351-09500 series, and
76351-09600 series, which have been repaired in accordance with ORI No.
76350-065 or ORI No. 76350-065, Revision A. ASB 76-66-50 describes
procedures for inspecting each MGB lower housing jet bore for leaking
oil, paint or caulk blistering, and liner protrusion. If there is any
liner protrusion or leaking oil between the

[[Page 149]]

liner and the housing, the ASB requires replacing the MGB. If there is
paint or caulk blistering, the ASB requires further inspecting for
leaking oil by replacing the jet bore packing, performing a ground run
of the main rotor for 30 minutes, and re-inspecting the jet bore for
leaking oil.
This information is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in the ADDRESSES section.

Other Related Service Information

We also reviewed Sikorsky ORI No. 76350-065, Revision B, dated June
10, 2011; Revision C, dated June 27, 2011; Revision D, dated January
20, 2012; Revision E, dated January 27, 2012; and Revision F, dated May
10, 2012. This service information describes procedures for repairing
the retaining ring groove areas of the MGB jet bores and installing
retaining pins in the jet bore liners.

Differences Between This AD and the Service Information

The ASB specifies compliance by a specific calendar date, while the
compliance time in this AD is in hours TIS. The ASB does not specify a
terminating action for the recurring inspections of the MGB jet bores;
while this AD does specify a terminating action for the recurring
inspections.

Costs of Compliance

We estimate that this AD affects 53 helicopters of U.S. Registry.
We estimate that operators may incur the following costs in order to
comply with this AD. At an average labor rate of $85 per work-hour,
inspecting the jet bore liners requires about 1.1 work-hours, for a
cost per helicopter of $94 and a total cost to US operators of $4,982
per inspection cycle. If required, repairing a jet bore liner requires
about 14 work-hours, and required parts cost $200, for a cost per
helicopter of $1,390. If required, replacing the MGB requires about 134
work-hours, and required parts cost $994,000, for a cost per helicopter
of $1,005,390.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect 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.
For the reasons discussed above, I certify that this AD:
(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);
(3) Will not affect intrastate aviation in Alaska to the extent
that it justifies making a regulatory distinction; and
(4) 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.
We prepared an economic evaluation of the estimated costs to comply
with this AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):

2015-26-10 Sikorsky Aircraft Corporation (Sikorsky): Amendment 39-
18358; Docket FAA-2014-0335; Directorate Identifier 2013-SW-021-AD.

(a) Applicability

This AD applies to Sikorsky Model S-76A, S-76B, and S-76C
helicopters with a main gearbox (MGB) part number (P/N) 76351-09000
series, 76351-09500 series, and 76351-09600 series installed that
has been repaired in accordance with Sikorsky Overhaul and Repair
Instruction (ORI) No. 76350-065, dated November 12, 1982 (ORI 76350-
065), or ORI No. 76350-065, Revision A, dated September 21, 1984
(ORI 76350-065A), certificated in any category.

(b) Unsafe Condition

This AD defines the unsafe condition as an unsecured MGB lower
housing jet bore liner. This condition may cause the liner to move
out of place, allowing oil to leak from the MGB, resulting in MGB
failure and subsequent loss of control of the helicopter.

This AD becomes effective February 9, 2016.

(d) Compliance

You are responsible for performing each action required by this
AD within the specified compliance time unless it has already been
accomplished prior to that time.

(e) Required Actions

(1) Within 50 hours time-in-service (TIS), and thereafter at
intervals not to exceed 6 hours TIS, inspect each MGB lower housing
jet bore (jet bore), as depicted in Figures 3 and 4 of Sikorsky S-76
Alert Service Bulletin 76-66-50, Basic Issue, dated January 14, 2013
(ASB 76-66-50), for liner protrusion or movement, paint or caulk
blistering, or oil leakage.
(i) If there is any liner protrusion or movement, before further
flight, replace the MGB with an MGB that has not been repaired in
accordance with ORI 76350-065 or ORI 76350-065A, unless it has been
subsequently repaired in accordance with Sikorsky ORI No. 76350-065,
Revision B, dated June 10, 2011 (ORI 76350-065B); Sikorsky ORI No.
76350-065, Revision C, dated June 27, 2011 (ORI 76350-065C);
Sikorsky ORI No. 76350-065, Revision D, dated January 20, 2012 (ORI
76350-065D); Sikorsky ORI No. 76350-065, Revision E, dated January
27, 2012 (ORI 76350-065E); or Sikorsky ORI No. 76350-065, Revision
F, dated May 10, 2012 (ORI 76350-065F).
(ii) If there is any oil leakage or paint or caulk blistering,
inspect the jet bore for liner protrusion and perform a leakage
check by following the Accomplishment Instructions, Paragraphs
3.C.(1) through 3.C.(6)(a), of ASB 76-66-50.
(iii) If any moisture or droplets of MGB oil are visible on a
jet bore after accomplishing the leakage check specified in
paragraph 3.C.(6)(a) of ASB 76-66-50, repeat paragraphs 3.C(4)
through 3.C(6) of ASB 76-66-50. If any moisture or droplets of MGB
oil are still visible, before further flight, replace the MGB with
an MGB that has not been repaired in accordance with ORI 76350-065
or ORI 76350-065A, unless it has been subsequently repaired in
accordance with ORI 76350-065B, ORI 76350-065C, ORI 76350-065D, ORI
76350-065E, or ORI 76350-065F.

[[Page 150]]

(2) Within 3,750 hours TIS, replace the MGB with an MGB that has
not been repaired in accordance with ORI 76350-065 or ORI 76350-
065A, unless it has been subsequently repaired in accordance with
ORI 76350-065B, ORI 76350-065C, ORI 76350-065D, ORI 76350-065E, or
ORI 76350-065F. This is terminating action for the repetitive
inspections required by this AD.

(f) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Boston Aircraft Certification Office, FAA, may
approve AMOCs for this AD. Send your proposal to: Kirk Gustafson,
Aviation Safety Engineer, Boston Aircraft Certification Office,
Engine & Propeller Directorate, 12 New England Executive Park,
Burlington, Massachusetts 01803; telephone (781) 238-7190; email
<a href="/cdn-cgi/l/email-protection#503b39223b7e372523243136233f3e103631317e373f26">[email&#160;protected]</a>.
(2) For operations conducted under a 14 CFR part 119 operating
certificate or under 14 CFR part 91, subpart K, we suggest that you
notify your principal inspector, or lacking a principal inspector,
the manager of the local flight standards district office or
certificate holding district office before operating any aircraft
complying with this AD through an AMOC.

(g) Additional Information

Sikorsky Overhaul and Repair Instruction No. 76350-065, dated
November 12, 1982; Revision A, dated September 21, 1984; Revision B,
dated June 10, 2011; Revision C, dated June 27, 2011; Revision D,
dated January 20, 2012; Revision E, dated January 27, 2012; and
Revision F, dated May 10, 2012, which are not incorporated by
reference, contain additional information about the subject of this
AD. You may review a copy of this service information at the FAA,
Office of the Regional Counsel, Southwest Region, 10101 Hillwood
Pkwy., Room 6N-321, Fort Worth, Texas 76177.

(h) Subject

Joint Aircraft Service Component (JASC) Code: 6320, Main Rotor
Gearbox.

(i) Material Incorporated by Reference

(1) The Director of the Federal Register approved the
incorporation by reference of the service information listed in this
paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do
the actions required by this AD, unless the AD specifies otherwise.
(i) Sikorsky S-76 Alert Service Bulletin 76-66-50, Basic Issue,
dated January 14, 2013.
(ii) Reserved.
(3) For Sikorsky service information identified in this final
rule, contact Sikorsky Aircraft Corporation, Customer Service
Engineering, 124 Quarry Road, Trumbull, Connecticut 06611; telephone
1-800-Winged-S or 203-416-4299; email <a href="/cdn-cgi/l/email-protection#0d7e6466627f7e66747a6e7e4d7e6466627f7e6674236e6260">[email&#160;protected]</a>.
(4) You may view this service information at FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-
321, Fort Worth, Texas 76177. For information on the availability of
this material at the FAA, call (817) 222-5110.
(5) You may view this service information that is incorporated
by reference at the National Archives and Records Administration
(NARA). For information on the availability of this material at
NARA, call (202) 741-6030, or go to: <a href="http://www.archives.gov/federal-register/cfr/ibr-locations.html">http://www.archives.gov/federal-register/cfr/ibr-locations.html</a>.

Issued in Fort Worth, Texas, on December 23, 2015.
John Hardie,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 2015-33013 Filed 1-4-16; 8:45 am]
BILLING CODE 4910-13-P

Source: Official FAA Source ↗

Retrieved: Apr 6, 2026

Rights: U.S. Government Public Domain

This site is not affiliated with or endorsed by the FAA. Always verify with official sources.

View Official Source ↗ Find More ADs for Sikorsky Aircraft Corporation S-76A

Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

Applicability

Unsafe Condition

Required Actions

Compliance Time

Affected Aircraft

Federal Register Abstract

Document Text

Related Airworthiness Directives

2024-20-07 Recurring

2023-11-07

2022-05-10 Recurring

2017-19-01