[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]


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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.

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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