[Federal Register Volume 61, Number 140 (Friday, July 19, 1996)]
[Rules and Regulations]
[Pages 37675-37677]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-18294]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-SW-16-AD; Amendment 39-9696; AD 96-15-03]
RIN 2120-AA64
Airworthiness Directives; Sikorsky Aircraft Model S-76B
Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
-----------------------------------------------------------------------
SUMMARY: This amendment supersedes an existing Airworthiness Directive
(AD), applicable to Sikorsky Aircraft Model S-76B helicopters, that
requires an inspection of the drive shaft for cracks or loose balance
weights. This amendment also supersedes a Priority Letter AD that
currently requires repetitive inspections for cracks in the driveshaft
in helicopters with certain engine drive shaft assemblies (drive
shafts) installed. This amendment is prompted by a report of a fatigue
crack found in a drive shaft that was caused by fretting of a balance
weight rivet washer. The actions specified by this AD are intended to
prevent failure of the drive shaft, loss of power to the rotor system,
and a subsequent forced landing of the helicopter.
DATES: Effective August 19, 1996.
Comments for inclusion in the Rules Docket must be received on or
before September 17, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Assistant Chief Counsel, Attention:
Rules Docket No. 96-SW-16-AD, 2601 Meacham Blvd., Fort Worth, Texas
76137.
FOR FURTHER INFORMATION CONTACT: Mr. Terry Fahr, Aerospace Engineer,
Boston
[[Page 37676]]
Aircraft Certification Office, FAA, Engine and Propeller Directorate,
12 New England Executive Park, Burlington Massachusetts 01803,
telephone (617) 238-7155, fax (617) 238-7199.
SUPPLEMENTARY INFORMATION: On August 26, 1991, the FAA issued AD 91-19-
02, Amendment 39-8028 (56 FR 47378, September 19, 1991) to require an
initial and repetitive 25-hour interval inspections of the left and
right engine input drive shaft assemblies for loose balance weights or
cracks. On June 4, 1993, the FAA issued priority letter AD 93-11-05,
applicable to Sikorsky Aircraft Model S-76B helicopters, which requires
initial and repetitive inspections of certain engine drive shafts
assemblies for cracks only.
Both AD 91-19-02, issued August 26, 1991, and priority letter AD
93-11-05, issued June 4, 1993, require initial and repetitive
inspections of certain drive shafts assemblies for cracks. AD 91-19-02
also requires an inspection for loose drive shaft balance weights. As a
result of having two ADs that require different corrective actions,
operators may be confused about which corrective actions to perform.
Such confusion may lead an operator to inadvertently fail to comply
with the necessary safety requirements for those rotorcraft and result
in an unsafe condition. Therefore, due to the criticality of
maintaining the inspection of the drive shaft and the short compliance
time, this rule incorporates both corrective actions and must be issued
immediately to correct an unsafe condition.
Since the unsafe condition described is likely to exist or develop
on other Sikorsky Aircraft Model S-76B helicopters of the same type
design, this AD supersedes AD 91-19-02 and priority letter AD 93-11-05
and requires, within the next 6 hours time-in-service (TIS), an initial
inspection of Model S-76B helicopters with certain engine drive shafts;
balance weights or balance weight rivets (rivets); or balance weight
and rivet and washers combinations installed. If a rivet, rivet/washer
combination, or rivet/washer/balance weight combination is installed,
an initial inspection of the drive shaft is required for cracks and
loose balance weights, and thereafter, repetitive inspections every 6
hours TIS.
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. 96-SW-16-AD.'' The postcard will be date stamped and
returned to the commenter.
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.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, 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, 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 removing Amendment 39-8028 (56 FR
47378, September 19, 1991) and by adding a new airworthiness directive
(AD), Amendment 39-9696, to read as follows:
AD 96-15-03 SIKORSKY AIRCRAFT: Amendment 39-9696. Docket Number 96-
SW-16-AD. Supersedes Priority Letter AD 93-11-05, issued June 4,
1993, and AD 91-19-02, Amendment 39-8028.
Applicability: Sikorsky Aircraft S-76B helicopters, with engine
drive shaft assembly (drive shaft), part number (P/N) 76361-09202-
044, -047, -049, or -051, with either rivet, P/N CR3523P-8-XX, with
a washer or balance weight, or rivet, P/N NAS1738MW6-X, with or
without a washer, 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.
[[Page 37677]]
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the drive shaft, loss of power to the
rotor system, and a subsequent forced landing of the helicopter,
accomplish the following:
(a) Within 6 hours TIS after the effective date of this AD,
visually inspect the drive shaft for cracks in the area around each
rivet, using a 10X or higher magnifying glass, and inspect the drive
shaft for loose balance weights.
(1) The inspection for loose balance weights shall be performed
by grasping the balance weights by hand and attempting to move them
in both the radial and axial directions. Any movement of the balance
weights constitutes looseness.
(2) If a crack is found on the drive shaft or any balance weight
is loose, replace the drive shaft with an airworthy drive shaft
before further flight.
(b) Thereafter, inspect for cracks and loose balance weights at
intervals not to exceed 6 hours TIS from the last inspection.
(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, 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.
(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.
(e) This amendment becomes effective on August 19, 1996.
Issued in Fort Worth, Texas, on July 11, 1996.
Daniel P. Salvano,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 96-18294 Filed 7-18-96; 8:45 am]
BILLING CODE 4910-13-P
